WO2006065957A1

WO2006065957A1 - Hybrid-electric engine and components thereof

Info

Publication number: WO2006065957A1
Application number: PCT/US2005/045353
Authority: WO
Inventors: Tristan H. Calasanz
Original assignee: Tope-Mckay, Cary
Priority date: 2004-12-14
Filing date: 2005-12-14
Publication date: 2006-06-22

Abstract

Disclosed is a hybrid-electric engine comprising: a mechanical load; a chemical-based motor drivingly connected with the mechanical load for selectively providing mechanical power thereto; an electrical motor drivingly connected with the mechanical load for selectively providing mechanical power thereto; and a data processing system connected with the chemical-based motor and the electrical motor for monitoring the operation of the chemical-based motor and the electrical motor, and for ensuring that when the chemical-based motor is operated, it is operated at approximately its peak efficiency with any excess power being stored in an energy storage system for later use by the electrical motor, and when possible, the electrical motor operates as the only power source of the engine.

Description

HYBRID-ELECTRIC ENGINE AND COMPONENTS THEREOF

PRIORITY CLAIM

This application claims the benefit of priority to provisional application 60/636,851, titled "Hybrid Vehicle," and filed at the U.S. Patent Office on December 14, 2004 and provisional application 60/715,760, titled "Hybrid Motor Technology," and filed at the U.S. Patent Office on September 8, 2005.

BACKGROUND

(1) Technical Field

The present invention relates to the field of hybrid energy-source engines, and more specifically to a hybrid gas-electric engine and components thereof, where the hybrid gas-electric engine is designed primarily for slow, start/stop, low-gear operation.

(2) Related Art

In heavy traffic, for example, it might take a driver between 45 minutes and an hour to traverse a six-mile distance to work at a speed of between 6 and 8 miles per hour. Fuel economies are typically very poor at such low speeds with traditional gasoline or diesel- powered vehicles.

In addition, in developing countries, it is important that drivers adapt hybrid vehicles adapt hybrid vehicle technology to limit the pollution caused by 2-stroke engines used on home-grown tricycles. To overcome cost-of-adoption barriers, it would be desirable to develop a home-grown design that uses commonly-available, inexpensive, components configured for local driving conditions. In short, what is desired is an entry-level hybrid engine that is optimized for heavy traffic use.

It would be further desirable that such an engine system be scalable, that is it could be adapted for a wide variety of vehicles. Optimally, it would also be cheaply retrofittable for older, inefficient engines to reduce the consumption of automotive fuel. During travel in heavy traffic conditions, a driver typically shifts to low gear, drives for a few seconds, steps on the brakes, waits a few minutes, goes for a few more seconds, stops and then waits for several minutes more. During this period, the vehicle has inefficiently burned fuel and has added toxic gases to the atmosphere. Aside from this obvious effect, there are many other costs further up the supply chain in this scheme, such as unnecessary fuel expenses, unnecessary man-hours lost in the production of unnecessarily expended fuel, and the broader environmental and health costs both across communities and on a global scale. These other costs are less immediately apparent and are much more difficult to quantify.

It would be desirable to provide an easy to install "hybrid-electric black box" that would simply be another system that could be readily bolted onto the chassis and supports of an existing vehicle. After bolting the system to their chassis and run it, there would be many benefits including economic, financial, and health benefits as well as a subsequent reduction in fossil fuel consumption that is urgently needed to protect both local environmental conditions as well as the global climate.

A. References related to environmental issues:

[1] J Tsai, Y. Hu, C Yang, H Chiang, and L Chang (2003), Volatile Organic Profiles and Photochemical Potentials from Motorcycle Engine Exhaust: Journal of Air and Waste Management Association, published by Air & Waste Management Association.

[2] S. T. Leong, S. Muttamara and P. Laortanakul (2001), Evaluation of Air Pollution Burden from Contribution of Motorcycle Emission in Bangkok: Water, Air, & Soil Pollution, published by Springer Science+Business Media B.V.

[3] Philippines Environment Monitor, World Bank, 2002.

[4] Asian Development Bank (2003) "RETA 5937: Action Plans for Reducing Vehicle Emissions", http://www .adb.org/Vehicle-Emissions/reta5937.asp. [5] Ronald Subida, M.D., M.A. Velas, Daniel McNamara, Ph.D., "Integrated Environmental Strategies: Philippines Project Report - Metropolitan Manila", http://www.cleanairnet.Org/baq2004/l 527/articles-59313_nicnamara.pdf.

B. References related to the further improvement of the performance of hybrid-electric vehicles through simulation software:

[1] Shigeru Onoda, Student Member, IEEE, and AIi Emadi, Senior Member, IEEE, "PSIM-Based Modeling of Automotive Power Systems: Conventional, Electric, and Hybrid Electric Vehicles", IEEE Transactions on Vehicular Technology, Vol. 53, No. 2, March 2004.

[2] Joeri Van Mierlo and Gaston Maggetto, "Innovative Iteration Algorithm for a Vehicle Simulation Program", IEEE Transactions on Vehicular Technology, Vol. 53, No. 2, March 2004.

[3] Keith B. Wipke, Matthew R. Cuddy, and Steven D. Burch, "ADVISOR 2.1: A User-Friendly Advanced Powertrain Simulation Using a Combined Backward/Forward Approach, IEEE Transactions on Vehicular Technology, Vol. 48, No. 6, November 1999.

[4] Karen L. Butler, Member, IEEE, Mehrdad Ehsani, Fellow, IEEE, Preyas Kamath, Member, IEEE, "A Matlab-Based Modeling and Simulation Package for Electric and Hybrid Electric Vehicle Design", IEEE Transactions on Vehicular Technology, Vol. 48, No. 6, November 1999.

[5] Lino Guzzella and Alois Amstutz, CAE Tools for Quasi-Static Modeling and Optimization of Hybrid Powertrains, IEEE Transactions on Vehicular Technology, Vol. 48, No. 6, November 1999.

SUMMARY OF THE INVENTION

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features, and advantages of the present invention will be apparent from the following detailed descriptions of the various aspects of the invention in conjunction with reference to the following drawings attached.

DETAILED DESCRIPTION

The present invention relates to the field of hybrid energy-source engines, and more specifically to a hybrid gas-electric engine and components thereof, where the hybrid gas-electric engine is designed primarily for slow, start/stop, low-gear operation. The following description is presented to enable one of ordinary skill in the art to make and use the invention and to incorporate it in the context of particular applications. Various modifications, as well as a variety of uses in different applications will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to a wide range of embodiments. Thus, the present invention is not intended to be limited to the embodiments presented, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without necessarily being limited to these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention. The reader's attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All the features disclosed in this specification, (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Furthermore, any element in a claim that does not explicitly state "means for" performing a specified function, or "step for" performing a specific function, is not to be interpreted as a "means" or "step" clause as specified in 35 U.S. C. Section 112, Paragraph 6. In particular, the use of "step of or "act of in the claims herein is not intended to invoke the provisions of 35 U.S. C. 112, Paragraph 6.

(1) Introduction

The present invention is a hybrid-electric engine system that is effective for slow, start/stop, low-gear driving. In particular, the present invention is applicable to automobile-type vehicles driven in heavy traffic conditions. The hybrid-electric engine system taught herein is scalable in the sense that it could be built into a wide variety of vehicles, ranging from small tricycle-type vehicles common in many Asian cities and passenger automobiles to busses, trolleys, and trains. Hybrid-electric engines taught herein could also be adapted as a retrofit system for older inefficient engines, to radically reduce consumption of automotive fuel.

An example of a hybrid-electric engine actually reduced to practice according to the present invention has been adapted for use with a tricycle-type vehicle. Although, as can be readily understood by one of skill in the art, the hybrid-electric engine taught herein has a wide range of applications, the tricycle-type vehicle will be used as the primary context for this description. The tricycle was built from the ground-up and was fitted with a smaller engine than its conventional counterpart. Components were procured as parts, and were not created as built-from-scratch systems. This approach offered the greatest flexibility and also helped to ensure that the engine does not require specialized manufacturing and maintenance. All of the electronic control systems and the sinusoidal three-phase variable voltage variable frequency inverter created for the tricycle-type vehicle described herein are home-made using mainly commonly available components. The choices made for the types of motor and generator (initially, a three-phase 90-ampere automotive generator), and internal combustion engine ensure that it provides a cost- effective solution. The main DC operating voltage and the control voltages were chosen on the basis of efficiency and human safety.

The vehicle was fitted with a battery storage capacity that can deliver the full power requirement of a one-kilowatt, three-phase induction motor for a substantial period of time. In operation, while the electric motor is running, the 2.4-horsepower engine is completely shut-down. During this time, however, the conditions of all of the (12-volt, 7- amp-hour) batteries are monitored to prevent a deep-discharge condition in any one of the seven series-connected batteries. As configured, a deep discharge in any battery triggers an alarm. In the extreme case that the condition persists, the battery management system is empowered to shut-down the variable-frequency inverter in order to shut-down the motor. The generator used is a 90-ampere, three-phase automotive alternator. It's diodes were disconnected so that a custom-designed step-up transformer could be installed to serve the purpose of the charging system.

An 84-volt (nominal) DC system was chosen in order to minimize risks to passengers. Transformers were used to bring the operating AC voltage to 230 wye with a grounded neutral. All of the transformers and inductors were designed and built by local engineers and shops following specifications provided.

It is noteworthy that each of the three major system components, namely the controller- dispatcher, the variable-frequency inverter, and the intelligent battery charger, could also be used as a stand-alone device in other applications such as manufacturing and process automation systems. For example, the VFI can be used for variable-speed conveyors, variable-flow pumps, soft-starters, renewable energy resources, decentralized energy systems (DES), and other applications for inverters.

a. Technical Basis

Internal combustion engines that are fitted in vehicles such as automobiles, trucks, and locomotives, are rated at a power that will provide safety, comfort, and performance. It is very seldom that these power ratings are used in ordinary city and country conditions, and in the case of automotobile, even on the fastest highways. The engines, therefore, are provided with shaft loads that are much smaller than they are capable of. Consequently, they operate at very loads and are very inefficient at these loads. Most internal combustion engines are at their best efficiencies when operated starting at around 70% of their rated capacity. This is when the greatest proportion of the energy content of the fuel is used to do useful work. Specific "performance curves" are available upon request from engine manufacturers. These curves generally vary for each manufacturer and for each engine model.

An example performance curve graph is shown in FIG. 1 for the engine used in conjunction with the tricycle used herein. As can be seen from the graph, this engine is most efficient when operating between 75% and 97% of its rated load. In view of this, the controller-dispatcher implemented for the tricycle is designed to operate the engine around this zone, depending upon the amount of charge in the batteries and the load required by the shaft. The system provides more charging current when the charge in the batteries is low, and the opposite happens when the charge is high. In general, when the power developed is greater than the power required by the shaft for a given driving condition, the hybrid-electric engine stores such excess power in an electrical storage medium such as a battery. When the power demanded at the wheels is more than can be developed by the engine, the balance is provided for by the electrical system through a variable-frequency sinusoidal inverter to drive an electric motor. If the vehicle has to decelerate, a regenerative braking system is activated so that kinetic energy of the whole mass is stored into the battery. Similarly, if the vehicle has to go down an incline, the change in potential energy of this mass as it comes down is also recovered and stored in the battery for future use.

For a given application, in selecting a chemical fuel (in this case gasoline) engine, the goal is to select an engine having a size that permits it to be operated around this efficient zone given the kind of road conditions likely to be encountered and the load that it will transport. The exact loading scheme for a particular vehicle would have to be calibrated, and this will be dependent on the charge level of the batteries and other factors, such as the actual performance curve of the specific engine procured. The instruction set in the controller-dispatcher of the vehicle will start the engine and shift the load to it at, or near, the full capacity of the motor. Initially, the load on the engine is below that necessary for the engine to operate in its most efficient zone. After the full load has been applied to the engine, assuming more load is necessary to bring the engine to peak efficiency, the controller-dispatcher will provide additional load (in the form of shaft load) by activating the charging system. During this time, the controller-dispatcher will balance the engine power, the load required by the shaft, and the load on the generator to provide a relatively smooth ride.

The load rating of the electric motor is chosen to be a relatively large percentage of the capacity of the engine to allow the engine to be shut-down for long periods. The ampere- hour capacity of the battery installed on the vehicle sets the upper limit for the ratio of the running time to the charging time. A higher ampere-hour rating would enable the system to deliver a higher charging current to the batteries.

An block diagram for the present invention is shown in FIG. A. The system includes three main components, a chemical-based engine AOO, an electrical system A02, and a drive for the wheels A04. As can be seen, there are three mechanical drives provided in the wheel drive, namely one for the engine, one for the electric motor, and one for the generator. In operation, the hybrid-electric engine attempts to operate the chemical-based engine AOO at its peak efficiency. Excess power generated by the chemical-based engine AOO is stored in the electrical system A02. Power is provided to the wheel A04 by either the chemical-based engine AOO, the electric system A02, or a combination thereof. In addition, regenerative braking is used to recover energy from the wheel A04 and to store the energy in the electric system A02.

A hybrid-electric vehicle according to the present invention will operate the chemical- based engine AOO (typically an internal combustion engine using gasoline or diesel fuel) at its most efficient operating range. This varies from one engine to another. To achieve "least-cost" operation, the engine is operated at this most efficient range, if it has to be operated at all. If the load is insufficient for operation at this range, the system will provide it with load so that it operates within that efficient operating range. The load could be any machine, such as an alternator to charge a battery, or any other system that will take shaft power. The system will operate an electric motor (single or polyphase) if the load is outside this range, and when running it produces better efficiency.

An implementation block diagram of the hybrid-electric engine is shown in FIG. B, which provides more detail regarding the components of the invention. As can be seen, three operational connections are made to the drive shaft BOO which is, in turn, connected to the wheel A04. Note that these connections may be made in any manner known or developed in the art and that the connections may be made physically, magnetically, or by any other mechanism and may be temporary/periodic or permanent. As shown in the figure, the general components of the hybrid-electric engine include an alternator B 02 used to generate energy from a load on the drive shaft BOO. The energy so generated is stored in a battery B04. The battery, in turn, is connected to an inverter B06 to convert DC electricity therefrom into AC electricity in order to drive the three-phase AC electric motor B08, which, in turn provides power to drive the drive shaft BOO.

Further details of the energy storage system (battery B04) are shown in FIGs. C and D, which depict the generator and the battery charge-level controller, respectively. Generator shafts are usually designed to operate at a speed that will enable the generator to generate a frequency that is synchronized with the system frequency. This may be 50Hz or 60Hz depending on where it will be used. At the same time, the generator will not generate voltage at low shaft speeds. This invention will utilize this common generator to generate voltage at shaft speeds that may be higher or lower than the synchronous frequency for which they have been designed, in order that it will be able to charge the batteries, when required.

The charge-level controller monitors each of the batteries that are connected in series to determine their state of discharge, and monitors the level of charge for the whole system. From an algorithm, it determines the amount of charging current that it will allow at any given state. It has complete override functions for the amount of charging current. It also has an algorithm for direct control of the load for the purpose of reducing it or for shutting it down completely.

The storage system operates, such that energy from three sources are stored. These come from (1) the excess engine power, (2) the kinetic energy that is converted into current for charging the system batteries through regenerative braking, and (3) the change in potential energy when going downhill, which is also converted into current for charging the system batteries. A generator could be used for this conversion. An electric motor of the appropriate electrical characteristics could also perform this function. The size of the storage battery system to be used depends upon the size, or the demand of the motor used. The voltage rating of the battery and the size of the electric motor will be the basis for the selection of the generator. The hybrid-electric engine presented here calls for a generator that can supply the current requirements of the system at almost any reasonable shaft speed. An electric motor of the proper electrical characteristic and design will also serve the purpose of this generator. A protective mechanism is incorporated into the storage system so that each of the batteries in series are constantly monitored for imbalances in their charge levels. No battery may be allowed to go below a discharge voltage specified by the manufacturer for the design load currents that are to be expected by the system. In case of emergencies when the generator or the engine fail to operate, the storage system will directly control the "load-down" mechanism of the inverter to prevent the danger of a "deep-discharge" of the batteries. As can be seen in the example embodiment of the generator shown in FIG. C, power from the power source COO is sent through a current regulator C02, then to a field winding C04, which transfers power to the generator winding C06 via a variable magnetic field C08, thus applying power to the load ClO. The load ClO is monitored by a voltage sensor C 12, which, in turn, provides feedback to a controller CO 14 (typically a proportional integral, derivative (PID) controller having a particular set point Cl 6. The PID controller C 16, in turn, controls the operation of the current regulator C02.

A diagram of the various operations of the battery charge-level controller is shown in FIG. D. The charge level is constantly or periodically monitored DOO to determine whether the current is above the allowable charge level limit D02. If the current level is acceptable, battery charging continues D04, as does charge level monitoring DOO. On the other hand, if the charge level exceeds the allowable charge level limit D02, the current is limited to the allowable value at the given battery charge level D06, charging continues at the new current level, and the charge level is monitored D00.

In addition, the system the system includes a set of monitors for monitoring the parameters shown in the monitored parameters table EOO of FIG. E. Note that in any particular embodiment, the parameters shown and discussed herein may be either a subset or superset of those actually monitored. The primary purpose for monitoring the main parameters shown in the table is to allow for the implementation of safety-related control functions. As shown in the table, the set of main parameters includes semiconductor temperature, Vce(sat), VFI voltage and voltage imbalance, VFI current and current imbalance, phase fault on the polyphase system, short circuit, over and under frequency, charging voltage, charging current, low battery charge, battery overcharging, individual battery charge level, and regenerative braking levels. Their levels are looked at by algorithms that, in turn, adjust the semiconductor conduction and current, the VFI voltage, the VFI current, the charging voltage, the charging current, and the complete shutdown of the system, as shown in the controlled parameters table E02. Together the monitors and controls that operate based on the monitored parameters comprise the fault- protection system for the hybrid-electric engine. The electric motor is driven by a sinusoidal variable-frequency single or polyphase inverter. This inverter typically operates using semiconductor power switches. This can range from transistors to IGBTs depending upon the power requirements and the voltage of the battery system. The protection system assures that the operation of these power semiconductor switches (or their equivalents) are always within their "absolute maximum electrical ratings." Thus, the sinusoidal variable-frequency inverter is provided with protection systems that will prevent damage to the inverter system and to prevent the motor itself from being damaged during "fault" conditions and low frequency operation. The system will monitor the main parameters listed in the last paragraph that may cause damage to the system or its component.

In addition to the protection system, the hybrid-electric engine also includes a sinusoidal variable-frequency inverter system. This system is described in greater detail further below, but is summarized here. A reference polyphase sinusoidal signal is generated by a variable-frequency oscillator. The power transistor is switched, and the output generated by the system is compared with the reference. If the magnitude of the feedback signal is higher, the comparator "switches OFF" the power transistor. Conversely, when the feedback signal is lower than the reference signal, the comparator "switches ON" the power transistor. This happens for the upper half of the sine wave. After the upper half crosses the "zero" line, the oscillator and comparator transfers control to the other power transistor to generate the lower half of the sine wave. There can be as many of these controllers as there are number of phases. In a three-phase system, the reference sine waves are 120 degrees apart to produce outputs that are also 120 degrees apart.

All the parameters that have to be managed to achieve "least-cost" are managed at this system. Torques, currents, voltages, imbalance of currents and voltages, speeds, battery charge levels, frequency, power demand and regenerative charging commands from the driver of the vehicle, and other parameters, are monitored here. It follows a dynamic algorithm that controls the combination of power and operational parameters to achieve the desired "least-cost operation". While all the subsystems are provided with "distributed processing" safety mechanisms, this system also oversees that all of them are functional. An added feature is that the system also tracks the position and direction of the HEV and provides it with a time-stamp so as to allow unmanned operation, when desired. This system also manages the database so that efficiency, pollution and optimization studies could be performed for this system. A wireless interconnection with the network is also included in this system. This allows much greater flexibility in the optimization of the efficiencies, environmental load and other studies.

The invention, when applied to a larger vehicle, such as a bus can become a co- generation system. As such, it will utilize part of the energy from the jacket water and part of the energy from the exhaust gases to produce steam at 10 barg. This steam will be sent to a "Lithium-Bromide Absorption" system (or other such system) to generate chilled water at about 6 degrees Celsius to serve the air-conditioning requirements of the bus. hi this manner, the fuel which would have been used to produce the air-conditioned air would be conserved. An illustrative diagram of the effect of the co-generation system is shown in FIG. H. As can be seen, a large portion of the energy from the jacket water and exhaust gases that would otherwise have been released as waste to the environment is recovered for air-conditioning.

In large-scale applications, such as in buses or in locomotives, an abundant amount of waste energy is available from the jacket water and from the exhaust gases. In a typical system, this waste energy adds up to about 60% to 80% of the energy from the input fuel. This invention will recover about 1/3 to 1/2 of this waste energy. Some of the hot jacket water at about 90 degrees Celsius will be converted into steam at about 10 bars by the exhaust gases. The steam would be sent to a Lithium-Bromide absorption system to generate chilled water at 6 degrees Celsius for the air-conditioning requirements of the bus. This would be ideal because no energy from a separate fuel source will be needed. Efficiencies for systems like this, where co-generation is implemented would obviously be more efficient than those applied for small systems like automobiles.

b. Heavy Traffic Conditions Some of the characteristics of heavy traffic as it relates to the present invention are as follows:

• Idling: As the internal combustion engine idles for several minutes, it burns fuel very inefficiently, resulting in it becoming an environmental hazard. Furthermore, it simply sits on the road, so that it consumes fuel with no resulting benefit.

• Low gear: When a vehicle begins to move in low gear, its fuel efficiency is very low (very low miles-per-gallon). This consumption is roughly estimated by the amount of pressure that the foot exerts on the accelerator pedal which, in turn, releases more fuel into the combustion chamber. During this time, the vehicle has moved a very short distance compared to how much it would have moved had the same pressure been applied to the accelerator while driving on a highway.

• Low engine load: While the vehicle is in a low gear for prolonged periods, the amount of shaft power that is demanded on large engines is a small fraction of the engine's rated power. This same demand, when treated as a percentage of the rating of small engines is higher. The performance curves of engines are similar to that shown in FIG. 1. Directionally, when the shaft demand as a percentage of the rating is small, there is a corresponding penalty - more fuel consumption per mile. On the highway, this shaft demand is higher because of the effects of drag and friction. At higher gears, the actual percent load on the engine is increased, resulting in an improved fuel economy as also shown in FIG. 1.

A goal of the present invention is to decrease the amount of time that the engine is running at a low load percentage, by leaving most of the traction to the electric motor at these loads. In so doing, this motor must be powered by a source that can provide the higher energy requirement of the system, leading to larger ampere-hour battery ratings to sustain the load. This, in turn, will need a higher charging current from the generator. This generator will also receive a higher shaft input, tending to increase the percent load.

A "rule of thumb" under this setting of low gear, start/stop, heavy traffic is, "if the engine has to be run at all, it should be at, or near, its best efficiency region in its performance curve, and the capacity of the batteries must be considerably large to sustain the larger energy needed by the motor." The result is a smaller engine compared to conventional counterparts. The engine will need "partners" (battery bank, motor, and generator) which have high ratings.

A simulation of the tricycle embodiment of the invention was created to predict the ballpark efficiency of the same engine when operated with the hybrid components installed and without. A 15% or greater reduction in fuel consumption (measured in grams per kilowatt-hour) was predicted. An even greater reduction in fuel consumption is probable with tricycles existing on the streets because they have larger engines than the tricycle equipped with the hybrid-electric engine of the present invention.

c. Dispatch Curve and Action Sequence

As the hybrid-electric engine is operated, the controller-dispatcher receives signals from all of its inputs and utilizes the information therefrom to follow a "dispatch chart" that guides its issuance of commands to other equipment within the vehicle to ensure specific operating conditions. This dispatch chart generally embodies the rule of thumb set forth above. An example of such a chart is shown in FIG. 2. The legends "Pw," Pe," "Pm," and "Pch" stand for power at the shaft of the wheel, the engine, the motor, and the charging generator, respectively.

The controller-dispatcher translates the dispatch chart into a set of actions that are performed during the operation of the vehicle. The various portions of the dispatch chart and the corresponding actions are discussed in general below. The controller-dispatcher interprets the driver's acceleration, clutching, and braking commands so that the vehicle operates in the following manner: • The VFI frequency is increased, but its voltage output remains close to zero. The output voltage is ramped up to the level allowed by the current limiters in order to engage the magnetic coupling between the rotor and the rotating magnetic field of the three-phase stator. This action of increasing the strength of the magnetic field effectively decreases the so-called "slip" of the induction motor. The frequency increases and the vehicle accelerates.

• At a motor load of between 600 watts and 1500 watts (depending on the charge level of the battery), the shaft of the engine is engaged (this may be accomplished either automatically or manually) with the already rotating shaft of the drive to serve as its starter.

• A small DC motor is converted into a variable-torque actuator. It is given a signal to increase the opening of the throttle to allow more gas into the combustion chamber. The engine starts to drive the shaft as it takes over the load from the motor. At this point, the AC motor simply releases the load to the engine, as the engine throttle is opened wider until the whole shaft load is taken over by the engine. The effect of the reduction in "slip" is that it will smoothen the transition further. At the same time, the engine shaft is provided with a balancing load by activating the charger circuit to load the generator.

• The cross-over points of the dispatch chart shown in FIG. 2 will be modified by the controller-dispatcher as the vehicle progresses. The charging curve "Pch" will have a lower peak and a shorter duration if the charge levels of the batteries are high. The opposite is true when the charge levels are low. In addition, the motor "Pm" would de-load early with an earlier start of "Pe." The dispatch chart becomes dynamic when the vehicle moves. The main factor that influences this dynamism is the amount of energy consumed from the batteries. A longer time at low shaft power will result in a significant decrease in battery charge. This condition shifts the cross-over point in the dispatch chart to the left. The space allowed for the digest is limited. For this reason, only sections of the schematic diagrams will be included. The whole schematics will be provided with the full paper.

(2) System Components/Major Systems

The present invention is intended to help increase the efficiency of a vehicle driven by a chemical-fueled engine, typically in the form of a gasoline or diesel fuel engine or an engine that uses gasoline or diesel fuel in combination with other solid, liquid, or gaseous fuels. With increased efficiency, the hybrid-electric engine helps to reduce the overall cost of delivering products and/or passengers over given distances. Hybrid-electric systems installed in automobiles are gaining sales traction and are now being promoted in many countries as a desirable technology for the present and future.

Present hybrid-electric vehicles have indeed shown an ability to improve operational efficiencies. Current models have proven their worth on the high-speed road systems of the United States and Japan. Such vehicles also perform better than their conventional counterparts on city streets. However, they are not designed for city streets, where traffic is very slow (typically less than 5 miles per hour), principally consisting of low-gear, start-stop operation. It is an object of the present invention to provide a hybrid-electric engine system that is able to operate efficiently and optimally in slow, low-gear, start- stop conditions.

The hybrid-electric system of the present invention can be fitted to automobiles, buses, trucks, and other vehicles that often travel under heavy traffic conditions. The design of the hybrid-electric engine presented herein is such that the internal combustion engine will operate at its peak efficiency whenever it is operated. If, in so doing, there will be excess power, this power will be used to charge batteries that will, later on, supply the requirements of a variable-speed AC motor. Control of the speed is accomplished by varying the frequency of the electric supply to the motor. Efficiency of conversion from DC to sinusoidal AC is accomplished with the use of solid-state switching technology. Monitors and controls are provided so that solid-state devices as well as the electrical and mechanical components are always operated within their ratings. The control and dispatching functions are performed within a micro-controller system with software and hardware peripherals that are specifically designed for such an application.

The hybrid-electric engine discussed herein is comprised of a variety of electrical, mechanical, and data processing components. Three of the principal components used for controlling and operating the engine are discussed in greater detail below.

a. The Controller-Dispatcher

The controller-dispatcher is a general-purpose component that will be used to implement all the functions of a hybrid-electric engine for vehicles on which it will be installed. It is equipped with input and output ports (I/O) that can accept voltage or current sensor or control signals from any outside device and provide voltage or current to any actuator. In the tricycle, common example voltage levels are in the range of 0 to 5 volts, while common example current levels are in the range of 0 to 20 micro-amps (ma). These will be converted later on into more common, industry standard ranges of 1 to 5 volts and 4 to 20 ma.

In the tricycle example, the data outputs to the different channels are not latched, as is the common practice. The 8-bit output is sent directly to a digital-to-analog converter (DAC), whose output is sent to a signal-conditioning circuit. Analog switches distribute this output to the various channels that are provided with the appropriate capacitors to store the information for the actuators. Each of the channels is fast-scanned and the data is stored in capacitors, so that the voltages sent to the actuators are stable. This method radically simplifies the calibration process. There is only one signal- conditioner whose zero and span adjustments would be manipulated. Other adjustments are done on the software level, where each channel is provided with a multiplier that is applied on the parameter corresponding to that channel. This scheme also drastically reduces component count and the associated control circuitry.

The controller-dispatcher is at the center of the hybrid-electric engine system. Hardware used to implement the controller-dispatcher can be any special or general-purpose data processing system (computer) with sufficient storage, processing capability, and inputs. For example, in prototyping/design, a commonly-available laptop computer can be used, using any available version of MS DOS and command-line LINUX. The control software can be adapted for use with both operating systems. Of course, once designed for a specific application, the control software and hardware can be formed as a standalone single-board micro-computer. The chart shown in FIG. 3 shows the general path of communication between the various modules of the present invention.

Although the controller-dispatcher has been adapted for the hybrid-electric motor described herein, it is applicable to any such system. The main function of the controller- dispatcher is to monitor the power demand at the wheels and to balance the distribution of power and energy needed at the wheels in a manner that provides for optimal work utilization for a given amount of fuel. This system is similar to the Load-Dispatch System or Supervisory Control and Data Acquisition System (SCADA) of an electric power system. The SCADA takes in the value of frequency and all the parameters for the generating power plants and for the various connected loads on the system. After all the data are in, it looks at the value of frequency and compares it with the desired value to determine whether the load given by the generating power plants are too high or too low. Thereafter, the SCADA will adjust the load so that the frequency is maintained at a specified value, while generating power at the least cost. However, if the SCADA will need to bring down the load of an efficient power plant below its optimum operating capacity, the SCADA will put load on the grid by activating a huge pump to bring water from a lower elevation to a higher one. When the load increases to the point that the least-cost dispatch will be disturbed, the SCADA will activate the pump in the other direction as a turbine-generator to generate the required electricity. The SCADA for the power system is analogous to the controller-dispatcher for a hybrid-electric vehicle using the engine described herein. As a very brief summary, the controller-dispatcher runs a generator to store electric energy into a storage battery when there is excess power, and it runs an electric motor from the storage battery when there is need for power. It also recovers kinetic energy when decelerating and change in potential energy when going down an incline.

The invention described here is for general purpose use. It may be applied to any hybrid- electric system. Only the interfacing (inputs and outputs) would need to be reviewed/adapted to ensure that the proper levels of input/output signals are provided.

In one embodiment, designed to be widely compatable, the controller-dispatcher is a multiple input and output controller that uses TTL level, 1-volt to 5-volt levels, 4 ma to 20 ma and floating contacts (that can be semiconductor-based that are opto-isolated or mechanical relay contacts). The controller-dispatcher is at the heart of this invention's implementation of a hybrid-electric System. The controller/dispatcher simply gathers all parameters related to driving power and to power demand. After this, it decides how it will distribute driving power to the various loads, and whether this will take the form of mechanical power or electrical power. It will implement an algorithm that requires the operation of the internal combustion engine at its optimized capacity, such that when optimized operation is higher than the demand, the controller-dispatcher will activate the generator to charge the batteries. If the vehicle is starting from rest, the controller- dispatcher will activate the variable-frequency inverter to take energy from the batteries, convert it into alternating current and supply the motor with power to give it prime- moving torque. It maintains communication links with the other modules of the vehicle. Details of all these communication links are discussed below.

The software will make the decisions that will implement the functions described above. In reduction to practice, software has been written in at least three generalized platforms, although may be easily adopted to other platforms. The platforms used in reduction to practice include (1) C for MS DOS, (2) C for LINUX, and (3) Firmware machine codes for Z8 micro-controller or other microprocessors and micro-controllers. The hardware used has ranged from a lower-end portable PC, to compact stand-alone micro-controllers or microprocessors. Inputs and outputs used were multiplexed and used the bi-directional tri-state approach. Further, the input/output ports were standardized at (1) eight-bit TTL levels, (2) 4 ma to 20 ma current loops, (3) 1-volt to 5-volt levels, and (4) floating contacts. All other voltage and current levels that are outside these schemes were included through pluggable enhancement modules. The floating contacts can be semiconductor-based that are opto-isolated, or similar, or mechanical relay contacts.

The various inteactions of the controller-dispatcher in a vehicle are depicted in FIG. I, where the connections between the controller-dispatcher 100 and the annunciator 102, the VFI 104, the charger and regenerative system 106, the accelerator 108, the mechanical brakes 110, and the mechanical drive 112 (in-turn connected with the wheels 114). The controller/dispatcher simply gathers all parameters related to driving power and to power demand. After this, it decides how driving power will be distributed to the various loads, and whether this will take the form of mechanical power or electrical power. The controller-dispatcher 100 implements an algorithm that requires the operation of the internal combustion engine at its optimized capacity, such that when optimized operation is higher than the demand, the controller-dispatcher 100 will activate the generator to charge the batteries. If the vehicle is starting from rest, the controller-dispatcher 100 will activate the VFI 104 to take energy from the batteries, convert it into alternating current and supply the motor with power to give it prime-moving torque. Various interactions between the controller-dispatcher 100 and other components are described in greater detail below. The interactions are described in terms of the various signals sent within the system, and are presented in a component-by-component manner.

Signals between the controller-dispatcher 100 and the variable-frequency inverter 104: "c2v" - Through this channel, the controller-dispatcher provides the VFI 104 commands related to frequency, voltage and current. These parameters are used to control the speed and torque that will be delivered by the electric motor to the shaft.

"v2c" - Through this channel, the VFI 104 provides the controller-dispatcher with the values of voltage per phase, current per phase, reference voltages and currents per phase, Vce(Sat) per IGBT, and the temperature of each of the IGBTs.

"v2d" - Through this channel, the VFI 104 supplies polyphase (three phase) voltage and current, as dictated by the controller-dispatcher 100.

Signals between the controller-dispatcher 100 and the charger and regenerative brake system 106:

"c2cb" - The controller-dispatcher 100 sends a charging current set point through this channel to the charger and regenerative brake system 106 for the conversion and storage of mechanical energy into electrical energy. This includes three functions, namely, (1) charging the batteries because the load is not enough and the batteries need charging, (2) converting kinetic energy into electrical charge for the batteries (regenerative braking), and (3) converting change in potential energy into electrical charge for the batteries (regenerative braking). The charger and regenerative brake system 106 checks its charge level map and decides how much of the charging current it will allow. The charger and regenerative brake system 106 has the last say on the value of charging current and has an override function that is intended to safeguard the integrity of the batteries.

"cb2c" - The charger and regenerative brake system 106 provides the controller- dispatcher 100 with parameter values of terminal voltage of the battery bank, the high and low value for each of the batteries (or cells) that are connected in series, and the current value of charging or discharging current.

Signals between the controller-dispatcher 100 and the mechanical drives 112 "c2d" - The controller-dispatcher sends the instruction to the mechanical drives module 112 to start or stop the chemical-based (in this case, internal combustion) engine (and on to the wheels 114). From then on, it gives instructions to open or close the throttle valve of the internal combustion engine and to what percent opening. It also gives instructions on which clutch to activate so that a particular gear or belt is put on the system.

"d2c" - The mechanical drives module 112 sends back the value of the torque of the internal combustion engine to the controller-dispatcher, as well as, the status of the clutch and the gear or belt systems. It also gives the controller- dispatcher the information on how much braking is required by the driver. In this way, the controller-dispatcher is provided with data with which to dispatch the generator for regenerative braking.

Signals between the controller-dispatcher 100 and the annunciator 102.

"c2n" - The controller-dispatcher IOOsends the following parameters to the Annunciator 102:

• AC - frequency, voltage, current, and imbalance of voltage and of current.

• DC - battery terminal voltage, charging and discharging currents, high and low status of each of the batteries (or cells) connected in series.

• VFI - current and voltage settings, Vce(Sat) values, and temperature readings.

• Motor - torque, speed, temperature, imbalance of voltages and currents.

• Generator - excitation field current, voltage, RPM, and torque. • Engine - RPM, %throttle, and torque.

• Wheel - RPM, and torque.

Signals between the controller-dispatcher 100 and the accelerator 108

"ac2c" - The accelerator 108 is one of the interfaces between the driver and the system. It is here that the driver indicates the system's need for more driving power. The controller-dispatcher algorithm determines which prime-mover to dispatch and what power it will be required to carry.

Flow charts for various processes that take place in conjunction with the controller- dispatcher 100 are depicted in FIGs. J through M. A snapshot of the decision-making process for starting the engine and charging the batteries is shown in FIG. J. The criterion is the charge level of the batteries and the historical data on the driving conditions and terrain. As shown in the flowchart, the charge level of the batteries is measured JOO, and this measurement is factored in with past performance and condition predictions J02. The prediction is by the controller-dispatcher to determine whether to start the engine and charge earlier J04, to start the engine and charge later J06, or follow a standard routine JO 8.

An example of a hardware communication interface from TTL to an analog actuator for use in the present invention is shown in FIG. K. The current-loop design shown converts the TTL output of the controller-dispatcher 100 to drive an actuator. The diagram shows the signal progressing from an 8-bit latch KOO to an appropriately selected DAC K02. Next, the signal is converted from a voltage signal to a current signal K04. The current signal is then sent to a current receiver K06, then to a signal conditioner KO 8, and finally to a driven device KlO. As non-limiting examples, this circuit can be used to drive the throttle valve of the gasoline engine through a current or voltage to torque converter technique. Enhancements in the design are in the area of components, layout, modularity, noise-immunity, and ease of calibration. An example of a hardware communication interface from an analog output to TTL for use in the present invention is shown in FIG. L. In this example, the current-loop design shown converts analog inputs from the outside world into TTL levels so that their values can be taken into the controller-dispatcher algorithm. As shown, a signal is received from an analog source LOO and is provided to a signal conditioner L02. The signal is then converted from a voltage signal to a current signal L04. The current signal is then sent to a current receiver L06 and then to an analog-to-digital converter (ADC) L08. Finally, the resulting digital signal is converted to a TTL signal LlO. As non-limiting examples, this circuit can be used to take in torque values, currents, voltages, and other parameters. Enhancements in the design are in the area of components, layout, modularity, noise-immunity, and ease of calibration.

b. The Multi-Phase Sinusoidal Variable Voltage and Variable-Frequency Inverter In the specific example used in conjunction with the tricycle embodiment of the present invention, the variable-frequency inverter (VFI) takes DC input from a series-connected battery bank composed of seven 12- volt nominal cells and provides a sinusoidal variable voltage variable frequency three-phase 230-volt wye output. In this particular example, the wye output has been chosen so that the line-to-ground voltage does not significantly go beyond 133 volts. Note that the 105 volts DC while charging is close to this value.

The sine wave is generated in the this example by the following steps:

• Two half parts of a sine wave are encoded in one electrically-erasable programmable read-only memory (EEPROM), E(a).

• At a phase spacing of 120 degrees, another two halves of a sine wave are encoded in another EEPROM, E(b). Note that this is like shifting and rotating E(a) so that the portion of the wave that exceeds E(a) is located at the starting point of E(a).

• At a space of 240 degrees from E(a), encode another two halves of a sine wave into another EEPROM, E(c) using the same procedure. • Connect the address pins of the three EEPROMs to the output pins of two cascaded binary counters, whose less significant byte takes its clock input from the output of an astable multivibrator.

• Connect the pins of a programmable logic device (PLD) to the address pins. This PLD is programmed to provide a logic "1" output for the first half sine wave to control the switch on one side of the output transformer, and a logic "0" that is inverted to become a logic "1" for the next half. A logic "1" on one side allows that insulated-bate bipolar transistor (IGBT) to be switched, to pull down one side of the transformer.

• Provide DACs for each of the three EEPROMs and condition these half sine waves to become reference signals to three comparators.

• The other inputs to these comparators come from conditioned feedback signals taken from the output of the VFI (input to rectifier) and the current sensors. Note that a simplified diagram of the output section of the VFI is shown in FIG. 4.

• In the switching section of the VFI, a simplified diagram of which is shown in FIG. 5, the three-input AND gate accepts voltage-switchign input at pin 3, instantaneous current at pin 2, and a signal that determines which half-section of the output section of the VFI at pin 4. Pin 4 goes to logic "1," and if the voltage is lower than the reference half sine wave AND the current is lower than the dynamic reference, then the IGBT at that side will switch ON until either the voltage OR the current reference signals are surpassed. A "dynamic reference" signal is provided to all of the three phases, such that an abnormally high current in any phase will generate a signal that will quickly bring down the amplitudes of all of the half sine wave reference voltages, so that the output voltages will be brought down. This provides for a safe shut-down function. A "line-to-line" short simply causes a shut-down, and the system returns to normal operation when the short is removed.

Note that for the tricycle embodiment described herein, although an automatic clutch could have been provided for the electric mode, a manual clutch was chosen to give a driver an environment very similar to the one in which they are used to driving. As the driver manipulates the clutch, he or she effectively controls the dynamic reference. When the driver operates the accelerator, he or she controls the frequency, and when he or she steps on the brakes, some kinetic energy and/or difference in potential energy is recovered and stored in the batteries.

A combination of actual waveforms (oscilloscope tracings) taken from the example VFI are combined into vertical diagram portions and shown in FIG. 6. Portion A of the figure is the reference signal coming from the EEPROM and accepted at pin 2 of the LM311, as shown in FIG. 5 (***what is this?). The upper half of portion B goes to the gate of the IGBT on the left of FIG. 4, and the lower half goes to the gate at the right. Portion C determines whether it would be the left or the right IGBT that should switch. Portion D is the sinusoidal output indicated in FIG. 4. The current input is taken from the pilot windings of the inductors at the collectors of the IGBTs. It operates along the same principle as the current transformer.

The main function of this component of the hybrid-electric engine is to convert DC power stored in batteries into AC power to be used by a three-phase induction motor. It should be apparent to one of skill in the art that the invention can be adapted for an arbitrary-phase motor, though. The induction motor has been so chosen because it is readily available in the market; it is also affordable safe to operate and sturdy. Because of its inherent slip, it can be used in start-stop conditions under a very wide range of power parameters, such as voltage, current, and frequency.

This variable-frequency drive is designed to provide electrical drive to a wide range of electric motors. When used with the specified alternative hybrid-electric vehicle, it is provided with settings that would provide the requirements of the motor safely and efficiently. Such settings are in the form of potentiometers that are so set to limit operation to certain minimum and maximum voltages and frequencies.

Sinusoidal single and/or polyphase variable frequency switching inverters are the most desirable way of generating alternating current for AC appliances from a direct current (DC) source for the following reasons:

(1) Sinusoidal. This waveform produces the least amount of transients, harmonics and core loss in an appliance connected to the sinusoidal power source.

(2) Switching Technology. Solid-state switches turn the power completely ON, or completely OFF. This action limits the power loss to a minimum. This loss decreases as "rise time" and the "fall time" of the switching wave-front gets faster.

(3) Low Switching (Vce-Saturation) Voltage. The other component of the power loss is the quantity derived by multiplying the switched "current" (Ic) with the voltage across the "collector" and the "emitter" (Vce-Sat) of the solid-state device. Since the "Vce-Sat" is a small value that ranges between 0.3 volt and 2.5 volts, this power loss is limited to the value of the Vce-Sat. Vce-Sat for a given bipolar solid-state device is dependent upon current and its junction temperature. In a switching system, therefore, the loss as a percentage of the power delivered becomes smaller as the operating voltage is increased. If the analog and the switching methods are compare, for example, switching technology applications will have losses which may be only about 15% of its analog counterpart application when both are operated at 12 volts. As the operating voltage is increased, this switching loss becomes a lower percentage, and can be as low as 2.5% of its analog counterpart in a 100-volt system.

(4) Polyphase System. In a polyphase system that is generated from a mechanically driven generator, the poles are so mechanically configured and accurately machined and aligned so as to produce magnetic fields that build up in accordance with a specified angle - 120 degrees for a 3 -phase system. This is much more easily implemented in a solid-stage system. Many popular applications were to have an electric motor be driven from an existing AC power source to drive a DC generator. The output would be sent to a variable-speed DC motor through a speed controller. In contrast, a solid-state system could produce the precise angles and variable frequency to drive a polyphase motor and eliminate the need for a set-up similar to the one mentioned above.

(5) Areas Suitable for Solid-State Polyphase Systems. Applications for such solid- state systems are limited by power and voltage requirements. Currently and in the near future, the niche for solid-stage polyphase systems is in the production of the desired electrical and/or mechanical power from an already existing electrical power source. One of the system's main roles is to provide flexibility in parameters, such as, power, frequency, voltage, current, and rotational/translational speed among others.

The present invention provides a home-grown version of a switching sinusoidal variable frequency inverter. It is designed so that all the control systems can be used for any DC voltage source. Only the output transformer needs to be replaced for the corresponding source.

This invention is so designed that it mimics the control of a manufacturing process within an electrical power system. A manufacturing process deals with "values of process parameters" (PV), and "set point value" (SV). The control algorithm of a manufacturing process is organized according the type of error correction that is applied. "PID Controllers" (proportional-integral-differential) have dominated this field for a very long time and are here to stay. Additional examples are the "feed-forward" and the "predictive" methods, each having a specific niche in the manufacturing sector.

Very briefly, the control algorithm follows the following steps:

(1) Here is a "set-point value" (SV).

(2) "Switch ON" the IGBT so that the "process value" (PV) goes in the "direction" of the SV.

(3) Provide a "comparator" to "Switch OFF" the IGBT when the PV is greater than the SV.

(4) This "comparator" also "Switches ON" the IGBT when the PV lower than the SV.

This methodology effectively "forces" the PV to follow the SV as it goes up or down. In this invention, the SV is presented as a "sine-wave." The PV will follow the SV in a saw-tooth fashion whose "period" is limited only by the "propagation delay" times of the components, starting from the output of the comparator, back to the same output of the same comparator. The "smoothening" process is accomplished by capacitors, inductors, and by designing the comparator for a very high gain.

The production of the sine wave is described in detail below. The description will be for Phase A. Phases B and C will follow the same process, except that the (ROM) reference signals are 120 degrees apart. The following paragraphs are discussed in conjunction with FIGs. M through R of the drawings.

Reference Signal Generation A reference rectified sine wave with a specified frequency and amplitude is generated at the control board. An astable oscillator MOO is used to generate variable frequency. A binary counter M02 counts the number of logic transitions that emanate from the oscillator MOO, incrementing as the transitions are received. In the exemplary embodiment described herein, comprising a three-phase system, three ROMs M04 (shown in the figure as RAMs), each containing information on the value of the reference voltage at any phase angle, are driven by the counter M02. Each of the three ROMs M04 has an identical sine wave value, except that the phase angles of each ROM M04 is spaced 120 degrees apart. Each of these ROMs M04 is fitted with a "digital-to-analog" converter M06 (DAC) that converts the encoded digital signal back to analog. A calibrating system is provided in order to adjust the output amplitude, so that the outputs of all three phases have the same amplitudes at their corresponding phase angles. This is accomplished by a set of signal conditioners M08. A monitoring circuit is also provided such that the "zero" of the sine wave is always at the "zero" of the analog system. This monitoring circuit operation is indicated by the reference blocks MlO. This assures that the positive have cycle delivers exactly the same amount of energy as the negative have cycle.

The Transformer.

As shown in FIG. N, the system is provided with a transformer in order to isolate the high voltage secondary winding NOO from the lower voltage primary winding N02. The secondary winding NOO is connected wye with the neutral connected to ground to provide the lowest possible line-to-ground voltage, resulting in better safety for the passengers. The center-tap of the transformer of each of the three phases is connected to the positive supply of a DC source. The collector of an "insulated-gate bipolar transistor" IGBT(a) is connected to the end of one coil, and the collector of another IGBT(b) is connected to the other end. The emitters of each pair of IGBTs - "a" and "b" are connected to power ground through a very low resistance that produces a voltage drop that is monitored by the current-sensing circuits.

The Switching Process (a single step thereof) The acts (events) below are performed in the switching process, and are shown in FIG. O. Note that the acts describe one overall step of the switching process, but that the same acts are applied for the other steps.

EventOl - Main Primary Coil.

IGBT(a) is switched to bring the corresponding end of the primary coil to ground, driving current through the coil and energizes it to produce a magnetic field that is building up.

EventO2 - Main Secondary Coil.

The magnetic field that is building up induces voltage at the secondary coil in one direction. The rate of this build-up is dependent upon the characteristics of the coil and iron in the magnetic circuit.

EventO3 - Feedback Secondary Coil.

As this voltage builds up, it is fed back to the control circuit through a feedback coil of the appropriate ratio to be compared to the reference signal.

EventO4 - Precision Full- Wave Rectifier.

The voltage sent back to the control board is sent to a precision full- wave rectifier so that rectified voltage at a specific amplitude ratio with the voltage at the secondary is seen at the control board.

EventO5 - Comparator.

The non-inverting input of the comparator is fed with the Reference Signal. The Rectified Voltage is fed to the inverting input. Initially, before the Main Primary Coil is switched, the output of the comparator is high because Reference Signal is made to increase, and no output is sent back to the board.

EventOό - Switching ON of IGBT(a). The high output of the comparator of EventO5 brings the gate of IGBT(a) high, and IGBT(a) is switched ON. This sends an on-rush of magnetizing current to the one end of the primary winding where IGBT(a) is connected, as mentioned in EventO2, inducing voltage at the secondary. A proportional voltage is sent back to the inverting input. The inverting input quickly overtakes the reference signal to cause the comparator output to go low.

EventO7 - Switching OFF of IGBT(a).

This low output brings down the gate of IGBT(a) to force IGBT(a) to go out of conduction, and it is switched OFF. In the meantime, the secondary is already delivering power to the load, and will consume the energy transferred to the secondary to bring the voltage down.

EventO8 - Feedback Voltage Lower than Reference.

The load forces the secondary output voltage to decrease, and this fact is reflected back to the inverting input of the comparator. At this state, the inverting input of the comparator is lower than its non-inverting input, and the comparator quickly raises its output high.

EventO9 - Part A of the Wave.

EventOβ through EventOδ is continuously repeated as a "free-running" switching process until the Reference Signal reaches a "zero" value.

EventlO - Part B of the Wave.

The process shifts attention to the control of IGBT(b). EventOl is repeated through EventO9 as the Reference Signal increases and decreases in amplitude to follow the rectified sine wave. The control process shifts back to IGBT(a) when the Reference Signal reaches a "zero" value again.

Eventl 1 - Continuous Repeat of Parts A and B. The whole process repeats itself to generate the positive half of the wave through IGBT(a) and the negative have through IGBT(b).

Phases B and C follow the same process.

The diagram shown in FIG. O shows an oscillator 000 connected with a reference block O02 and an AND gate O04. A signal from the reference block O02 and a conditioned signal O06 from the power electronics O08 are compared at a comparator 010, the output of which is fed into the other input of the AND gate O04. The output of the AND gate O04 is connected with the power electronics O08. The output of the power electronics is provided to the three-phase motor 010.

Which Side Control and "ZERO Crossing" Detector?.

This system puts a "logic 1" at the "AND-gate" of Figure 3 for IGBT(a) to be operated and a "logic 0" if it will not be operated. Similarly, it puts a "logic 1" at the "AND-gate" of the other side, i.e., if IGBT(b) would be operated and a "logic 0" if it will not be operated. The signal for the "AND-gate" comes from a programmable logic device. For this reason, the presence or absence of this signal is always at the exact time that it is required, and is always in sync with the rest of the system. Its presence or absence signifies a "ZERO-crossing".

Frequency Control.

The operating frequency control is provided with a minimum and a maximum limit at the VFI module side. The VFI is completely autonomous for these limits. Instructions for the operating frequency within the set limits, emanates from the "controller/dispatcher" module of the main patent application, entitled, "An Intelligent Vehicle that uses Fuel in an Internal Combustion Engine, in Combination with an AC Electric Motor, an AC Generator, a Battery Bank, and the Appropriate Mechanical Drive System in Order to Achieve High Overall Thermal Efficiencies by Optimizing the Vehicle's Operation to the Demands of the Traffic, Driving Habits of the Driver, and Road Conditions". This is achieved through a control signal that is decoded at this module and directly controls the oscillator constants.

Voltage Amplitude Control and Protection.

The voltage amplitude control is provided with a minimum and a maximum limit at the VFI module side. The VFI is completely autonomous for these limits. Control of the operating frequency voltage within the set limits, also emanates from the "controller/dispatcher" module of the main patent application, entitled, "An Intelligent Vehicle that uses Fuel in an Internal Combustion Engine, in Combination with an AC Electric Motor, an AC Generator, a Battery Bank, and the Appropriate Mechanical Drive System in Order to Achieve High Overall Thermal Efficiencies by Optimizing the Vehicle's Operation to the Demands of the Traffic, Driving Habits of the Driver, and Road Conditions". This is achieved through a control signal that is decoded at this module and directly controls the reference currents of the Digital-to-Analog converter.

Current Control and Protection.

"Current control" is dependent upon the load. While this may be so, the VFI independently checks the operating current and sets its own limit regardless of load or system demand. This must be so, in order that the VFI always operates at its own safe limits. Any current outside the safe operating limit, even if it is found only in one phase will activate the protection system so that the safe operating limits of all the phases will be shifted to a lower current value.

Protection Systems. (Please refer to Figure 4 - Protection System)

The protection system monitors the following main system parameters:

Semiconductor Temperature; Vce(sat); VFI Voltage & Imbalance; VFI Current & Imbalance; Phase Fault on 3Φ System; Short Circuit; Over & Under Frequency; Charging Voltage; Charging Current; Low Battery Charge; Battery Overcharging; Individual Battery Charge Level; Regenerative Braking Levels. An abnormality in any of these main system parameters will activate the protection system to bring the following parameters in the direction that is opposite that which has caused the abnormality. These controlled parameters are:

Semiconductor Current; VFI Voltage; VFI Current; Charging Voltage;

Charging Current; Complete System Shutdown

Short Circuit Protection System.

A short-circuit in any part of the system will cause a "system shut-down" even if the protective circuit breaker did not activate. An annunciator flag for that event is activated.

Torque Control and Magnetic Coupling.

Torque control is achieved by managing the magnetic coupling between the "rotor" and the "stator" of the motor. This is achieved by carefully arranging the frequency and the magnetic coupling such that the desired result is achieved.

Under-Frequency Conditions.

The "inductive reactance" "X(L)" of the motor varies with frequency, such that it is

X(L) = 2 * π* f * L.

X(L) becomes a low value when "f" is low, and may cause very high currents. Without considering the effect of "back-EMF" on the system, the current at 30 Hertz is double the current at 60 Hertz, when only the frequency has changed by half. When the effect of "back-EMF" is factored in, the value of current will be much more than double, because the "back-EMF" effectively reduces the voltage across the "L" to a value equal to the terminal voltage minus the "back-EMF".

Communication System.

Communication between the VFI and the outside world may take many forms. The form taken will be dictated by such items as proximity, and noise among others. In any case, the system maybe controlled via a current loop or a voltage source. When used in the vehicle, these are the only two ways that are reliable because of the fast changing commands that may be required by the driver. In a stationary application, as in a manufacturing plant, there may be some room for serial control, but this must be carefully thought out before implementing it. However, there will be no special issues in resorting to serial communication for monitoring purposes.

Brief Description of the Drawings

Figure 1 - The Signal Reference Generator.

This system starts with a variable frequency oscillator. A series of counters accumulate the number of logic transitions and present these to ROMs, in order that their digital contents would come out to the DACs, then to the signal conditioners and out to become the reference sine waves for a polyphase system.

Figure 2 - Primary is "independent single-phase" and Secondary is "WYE-

Connected".

Three independent inverters that are synchronized at 120 degrees apart, each develop their independent outputs and their respective secondary windings are connected "WYE".

Figure 3 — Block Diagram of Switching Process.

This diagram shows the relationship of the various active components. Only one side of one phase is presented here..

Figure 4 - VFI Protection System.

The main parameters are monitored and the causes of going beyond their limits are controlled.

Figure 5 - Switching Method. The layout shown is for one side, where it shows an "L" in series with the collector to limit the di/dt value, a reverse-biased diode to clip whatever voltage goes lower than the emitter, and a smoothening capacitor so that the high frequency switching signal is prevented from going into the transformer to cause heat from hysteresis loss.

Figure 6 - Measurement of Vce(sat).

The Vce saturation voltage is monitored each time the wave reaches peak, since this is indicative of the performance of the IGBT₅ and also indicates overload, bias failure, and a trend towards a more elevated temperature of operation, among others.

c. The Intelligent Battery Charger

The third major component of the invention is an intelligent battery charger that manages the charging current so that at no point during the charging process does is more current allowed into the batteries than is allowed by the current state of the batteries. The charger monitors the level of charge by taking measurements of the terminal voltage of the batteries connected in series, and, by its own hardwired system, limits this current.

The system also monitors the terminal voltage of each of the batteries that are connected in series and sends an alarm if any one of them were to come close to an overcharged condition. In any case, an IGBT switch in series with an inductor closes when the limit for the terminal voltage is reached. It regulates the terminal voltage of the battery. In this way, the uneven chemical condition of the batteries connected in series does not offer a source of concern.

An example of the relationship between the level of charge in the batteries and the charging current is shown in FIG. 7. C₀ represents the lead-acid battery's terminal voltage at its minimum charge level. This is around 12.2 volts while charging at about I₂₀ up to I_2.4 (the manufacturer's recommended charging limit) at a cell temperature of about 30 degrees Celsius (note that the numbers given in this discussion are observations in practice and may vary somewhat from one manufacturer to another). C₁ represents float charge at about 13.8 volts while charging at I₂₀, also depending on the temperature of the electrolyte. C₂ is the condition at around 75% to 85% charge and one may start observations at about 14.7 volts at a charging current of about I₅o. C₃ is the terminal voltage when the battery is fully charged and observation is usually started at around 15.0 volts at a charging current OfI_1O0.

A simplified schematic diagram of the system used to detect charge level is shown in FIG. 8. The system is a straight-forward analog sensing, amplification, and diode combination for providing the proper reference signal to the current controller. Note that all of the logic is hardwired and is designed to override any and all commands that may increase the charging current beyond the allowable values. The relevant signals may originate from the controller-dispatcher or from the regenerative braking system.

The circuit that controls the switching of the IGBT current switch is shown in FIG. 9. Note that the inductor that slows sown the build-up of current when switched is not shown.

Technical Field

The present invention relates to the charging and the discharging of batteries at rates that are allowed for their levels of charge. Batteries must not be allowed to discharge beyond a certain level while providing current to its connected load. Even more critical is the fact that the charging current for batteries must be related to their level of charge. This invention is one major component of another patent being applied for, entitled, "An Intelligent Vehicle that uses Fuel in an Internal Combustion Engine, in Combination with an AC Electric Motor, an AC Generator, a Battery Bank, and the Appropriate Mechanical Drive System in Order to Achieve High Overall Thermal Efficiencies by Optimizing the Vehicle's Operation to the Demands of the Traffic, Driving Habits of the Driver, and Road Conditions". Background

This system has been designed for the Hybrid-Electric vehicle mentioned above and its main function is to convert manage the charging and the discharging of storage batteries that are connected in series. Charging current is derived from an alternating current generator that is rated at 230 volts AC and 60 hertz. A sinusoidal polyphase variable- frequency inverter is connected to the batteries as load. The issues which the invention addresses are (1) when batteries are connected in series, the weakest of them all will dictate the amount of charge that it can take and the amount of power that it can deliver; (2) the use of an alternating current generator that is designed for a fixed synchronous speed at 60 hertz is being operated at varying shaft speeds; (3) the current drain from an independent load could cause "deep discharge" on the batteries; (4) operating temperatures; and (5) the desire to assure prolonged service life despite the excursions of voltages, charging currents, discharging currents, and shaft speeds.

Summary of the Invention

In this invention we present a technology for the management of the charging and the discharging currents in batteries that are connected in series, in such a way that their service life would be extended, despite the environment in which they are exposed to.

Charging Current in Accordance with Map of Charge Level. The invention carefully maps out the charge level of the battery bank, and by hard- wired algorithms allows only the amount of charging current that is appropriate for that charge level. Battery manufacturers often specify a "constant charging voltage" and the highest current that can be allowed while charging. Obviously, the intention is to provide a fast charge at the beginning of the charging cycle and as the battery charge level increases, the net charging voltage also decreases because the terminal voltage of the battery increases, while the charging voltage is held constant. This method is replaced with the mapped method described in this patent for a very important reason, and that is, that the regenerative braking process of the vehicle where this system is an integral part of kicks in at any moment, without a predetermined demand structure or demand algorithm. This invention ignores the demand, and decides on its own to allow only a value of current that is safe for its operation. This is done without any interference from any system outside itself. The philosophy of control resembles that of a limiter - operation may be allowed, provided that the parameter is below a maximum value, while this value changes in time.

Monitoring and Control of Charge Level of each Battery (Safety-Related). This invention is provided with a system that measures the level of charge of each battery. Two absolute levels of charge for each battery (this may also be a cell) are provided. Thus, there are two set-points, one for a "TOO HIGH" and another one for a "TOO LOW" state. A solid-state sequencer measures each battery (or cell) and compares this value with the two set-points. Any battery (or cell) that presents a measured value that is outside the band will trigger an alarm signal. The abnormality must be corrected within a reasonable time. An abnormality that persists over a predetermined reasonable time, will case the battery to disconnect itself from the charger and from the load.

The Voltage and Current Supplied by the AC Generator. This invention uses an AC generator in a slightly different usage manner, because it will be used outside its normal design operating range. It is designed to operate at a constant speed for 60 or for 50 hertz, now it will be operated at speeds that will be below and slightly above its rated speed. It is designed with a voltage regulator that makes its terminal voltage constant, regardless of load - between 0% and 100% load. It will also be demanded to provide only about 30% to 50% of its rated voltage output. This invention makes provisions for these issues in order to operate the system safely and efficiently.

Brief Description of the Drawings Figure 1 - Map of Relationship between Charge level and Charging Current.

This figure shows the relationship between the level of charge of the batteries and the charging current. Some battery manufacturers allow their batteries to be charged with currents that can reach 40% of the absolute value of the "ampere-hour" rating when its charge level is low. The circuitry will allow a charging current of Iχi at a range of charge from Co to Ci, Iχ_j to Iχ2 at range of charge from Cj to C2, Iχ2 ^to Iτ3 ^at range of charge from from C2 to

C₃-

Figure 2 - Charger Level and Charging Current Logic.

The charging current that is allowed for the batteries vary with the charge level. Each charge level calls for a charging current limit. With this in mind, this figure shows that the system monitors the charge level at any given time and allows any charging current that is lower than the limit for that charge to go to batteries. This logic is for the battery bank which is composed of several batteries in series.

Figure 3 — Monitoring of Charge Level of Each Battery (Safety Related).

The designer and user of batteries in series are sometimes caught by surprise that the battery system did not perform as intended and that enumerable losses were incurred as a consequence of only one of the battery failed. The system is provided with a solid-state monitor that sequences each individual battery to determine their level of charge and after doing so, provide an output signal to declare the status of each battery.

Figure 4 - Control of Charge Level of Each Battery (Safety Related). This Figure shows a system that is related to the integrity of the batteries. As a supplement and in contrast to the system shown in Figure 2 this figure shows that each of the batteries connected in series is monitored. A charge is too high in one battery and not in the others indicates that this one battery may no longer be operating as designed. A warning signal is issued, and when it is not corrected within a reasonable time, the system will be shut down. Similarly, a charge that is too low on one also indicates that this one battery may no longer be operating as designed. A warning is also issued and when it is not corrected within a reasonable time, the system will be shut down.

Figure 5 - Voltage Control Logic of AC Generator.

The generator field winding is directly controlled by a semiconductor switch that controls the average strength of the magnetic field developed by the field winding. This magnetism will provide the basis for the voltage generated by the generator. A sensor is fitted at the output of the generator so that a feedback signal could be brought back, by way of a PID circuit to the regulating switch of the field current. A set-point that can be dynamically controlled is provided so as to regulate the voltage from which the charging current will be derived.

Figure 6 - Charger Voltage Waveforms.

This figure gives the sine wave, which would have been the output of the generator if the PID controller (of Figure 5) did not change the magnetizing current at the field winding. The "clipped" sine wave is the terminal voltage of this same generator after the PID controller has manipulated the current at the field winding to provide safe charging voltage to the batteries.

Figure 7 — Current- Switching and Limiter. The system is provided with a current limiter operated by a semiconductor switch. A set-point that is dynamically controlled, using the "map" of Figure 1, is provided and is implemented by the control logic of Figure 2.

Detailed Description. (Management System for Charging Batteries)

This section will describe how the primary issues are resolved.

Charge Levels.

Charge levels are measured when there is current going into the battery (or cell), or current being taken from it. This invention divides the terminal voltage spectrum into three regions (please refer to Figure 1). From CQ to Ci is one region -

RegionOl; from Cj to C2 - Regionl2; and from C2 to C3 - Region23. RegionOl is able to accept the highest amount of charging current, and the battery charge is low. Ci is a significant battery condition. The voltage at this condition is called "float voltage". In practice, station batteries are operated at float. C2 is another significant condition. Automobiles, and other applications that use variable power are operated at the terminal voltage corresponding to this battery condition. Depending upon the temperature of the electrolyte, the battery is about 80% charged at this point. Batteries are sometimes brought to C3 but this is done only with extreme caution. A battery can be easily ruined if the conditions are not properly controlled. This invention provides safe and predictable battery-charging conditions regardless of charge level.

Safe Charging or Discharging Range for each Battery (or cell). The life of a battery (or cell) is shortened when its voltage is raised too high while charging, or if the charging current used is too high for that charge. The life of the battery (or cell) is also shortened if the discharging current brings the terminal voltage below safe limits specified by the manufacturer. The first condition is an overcharging condition and the latter is a deep-discharge condition. This invention is aware of these issues for each cell in series and provides protection that is described in Figure 4.

The Role of the AC Generator.

This invention will take an ordinary AC generator and modify it to meet the charging and safety requirements of the charging process. At low shaft speeds, the generated emf is brought to its desired value by providing a safe excitation current to the generator field winding. At higher shaft speeds, the generated emf is assured to be at a lower value that what it has been designed for by lowering the excitation current to the generator field. The output is rectified to become direct current to charge relatively large capacitors.

The Power-Switching Process.

The power switching process for controlling current values is accomplished using IGBTs. Control of the gate to switch the IGBT that limits the charging current is accomplished using opto-isolators to assure that the control and monitoring circuits are always at instrumentation voltage levels.

Protective Systems.

The protective mechanism to prevent overcharging is the reduction of the value of the field excitation current to "zero" and the deactivation of fail-safe relays that open when there is no current at its coil. The protective mechanism to prevent deep-charge is a current loop or a voltage signal that ramps down the current drawn by the load and removes the load through fail-safe relays.

Power and Energy Database with Capability for Remote Analysis.

All the parameters in this module are monitored by the controller/dispatcher and stored in a database that is available for study and analysis. As an option, this database, together with all the current parameters are telemetered in a wireless system to have them monitored remotely.

One of skill in the art will recognize that both the entire hybrid-electric engine described herein and its various components can be used in a very wide variety of applications from vehicles to stationary power generators, among many, many others. The scope of the invention is not intended to be limited by the specific examples described herein, but is intended to be afforded the full scope of the claims and that would be afforded given the skill of one skilled in the art.

Claims

CLAIMS What is claimed is:

1. A hybrid-electric engine comprising: a mechanical load; a chemical-based motor drivingly connected with the mechanical load for selectively providing mechanical power thereto; an electrical motor drivingly connected with the mechanical load for selectively providing mechanical power thereto; a data processing system connected with the chemical-based motor and the electrical motor for monitoring the operation of the chemical-based motor and the electrical motor, and for ensuring that when the chemical-based motor is operated, it is operated at approximately its peak efficiency with any excess power being stored in an energy storage system for later use by the electrical motor, and when possible, the electrical motor operates as the only power source of the engine.