CA2149009C - Apparatus for regulating an elevator motor - Google Patents
Apparatus for regulating an elevator motorInfo
- Publication number
- CA2149009C CA2149009C CA002149009A CA2149009A CA2149009C CA 2149009 C CA2149009 C CA 2149009C CA 002149009 A CA002149009 A CA 002149009A CA 2149009 A CA2149009 A CA 2149009A CA 2149009 C CA2149009 C CA 2149009C
- Authority
- CA
- Canada
- Prior art keywords
- motor
- speed
- frequency
- voltage
- motor speed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
- H02P29/04—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors by means of a separate brake
- H02P29/045—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors by means of a separate brake whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Elevator Control (AREA)
- Control Of Ac Motors In General (AREA)
- Control Of Electric Motors In General (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
Abstract
The invention relates to an apparatus for regulating the speed of an a.c. elevator motor by means of a frequency converter consisting of a rectifier bridge and an inverter bridge. The frequency of the frequency converter is adjusted until it corresponds to a frequency reference corresponding to the speed reference of the motor. The speed of the motor is measured to form a speed feedback signal.
According to the invention, the apparatus comprises means for correcting the speed reference on the basis of a change occurring in a voltage of an intermediate circuit between the rectifier bridge and the inverter bridge.
According to the invention, the apparatus comprises means for correcting the speed reference on the basis of a change occurring in a voltage of an intermediate circuit between the rectifier bridge and the inverter bridge.
Description
APPARATUS FOR REGULATING AN ELEVATOR MOTOR
The invention relates to an apparatus for regulating the speed of an alternating current (a.c.) motor, more particularly for an a.c. elevator motor.
The apparatus utilizes a frequency converter consisting of a rectifier bridge, an inverter bridge and an intermediate circuit between them.
By means of the frequency converter, the frequency of a supply network connected to the rectifier bridge is adjusted to obtain a frequency corresponding to a frequency reference determined by a speed reference of the motor. The motor speed is measured to form a speed feedback signal. The apparatus has voltage measuring elements for measuring the voltage of the intermediate circuit.
The drive motor used in an elevator is often an a.c. motor fed by a frequency converi:er controlling the frequency of the a.c. voltage feeding the motor. A commonly-used frequency converter consists of a rectifier connected to the supply network and via a direct current (d.c.) intermediate circuit to an inverter producing au a.c. voltage.
The speed of an asynchronous motor is determined by the frequency of the motor supply voltage, and the motor speed is generally adjusted by varying this frequency. The ability of the network and the motor control system to produce a sufficient motor torque depends on the current supply capacity of i:he network and the stability of the network voltage at a sufficient value. If the network voltage falls, then, above a certain speed limit, the motor will not receive sufficient power to maintain the speed. This problem is encountered in weak networks. In this respect, temporary power supply systems such as construction-time drives involve particularly difficult problems.
A previously-known solution in which the hoisting motor of an elevator is driven at a speed below the nominal speed during an undervoltage condition of the supply network is presented in Finnish Patent FI C 86053, granted to KONE C)y on July 10, 1992. In this method, the supply network voltage is measured and, when a reduction in the voltage is detected, the value
The invention relates to an apparatus for regulating the speed of an alternating current (a.c.) motor, more particularly for an a.c. elevator motor.
The apparatus utilizes a frequency converter consisting of a rectifier bridge, an inverter bridge and an intermediate circuit between them.
By means of the frequency converter, the frequency of a supply network connected to the rectifier bridge is adjusted to obtain a frequency corresponding to a frequency reference determined by a speed reference of the motor. The motor speed is measured to form a speed feedback signal. The apparatus has voltage measuring elements for measuring the voltage of the intermediate circuit.
The drive motor used in an elevator is often an a.c. motor fed by a frequency converi:er controlling the frequency of the a.c. voltage feeding the motor. A commonly-used frequency converter consists of a rectifier connected to the supply network and via a direct current (d.c.) intermediate circuit to an inverter producing au a.c. voltage.
The speed of an asynchronous motor is determined by the frequency of the motor supply voltage, and the motor speed is generally adjusted by varying this frequency. The ability of the network and the motor control system to produce a sufficient motor torque depends on the current supply capacity of i:he network and the stability of the network voltage at a sufficient value. If the network voltage falls, then, above a certain speed limit, the motor will not receive sufficient power to maintain the speed. This problem is encountered in weak networks. In this respect, temporary power supply systems such as construction-time drives involve particularly difficult problems.
A previously-known solution in which the hoisting motor of an elevator is driven at a speed below the nominal speed during an undervoltage condition of the supply network is presented in Finnish Patent FI C 86053, granted to KONE C)y on July 10, 1992. In this method, the supply network voltage is measured and, when a reduction in the voltage is detected, the value
2 of the motor speed reference is reduced. In this solution, however, the motor speed cannot adapt sufficiently fast to the changing conditions. Major deviations of the load torque from the rated value will result in a situation where the control system is unable to keep pace with the abrupt increase in the power requirement of the motor.
The object of the invention is to achieve an apparatus which enables an elevator motor to work even when the network voltage varies rapidly and even when the reduction in the voltage is relatively large. The apparatus has a frequency converter formed by a rectifier bridge, an inverter bridge, and an intermediate circuit between the rectifier bridge and the inverter bridge.
The apparatus also has voltage-measuring elements for the measurement of the voltage of the intermediate circuit, and further has a correction means for correcting the speed reference on the basis of a change in the voltage of the intermediate circuit. The frequency converter is used to produce from the frequency of a supply network connected to the rectifier bridge a frequency corresponding to a frequency reference depending on a speed reference for the motor. The speed of the motor is measured to form a speed feedback signal.
The apparatus may also comprise a limiter device which, based on the measured value of the voltage of the intermediate circuit, produces a coefficient by which the speed reference is multiplied in a multiplier element.
The apparatus may further comprise a memory and time-delay circuit which is designed to keep the coefficient at a constant value for a preset length of time.
The frequency converter may also comprise a torque regulator which additionally measures motor current. The torque developed by the motor is adjusted on the basis of the motor current, the frequency reference and the voltage of the intermediate circuit.
In the solution of the invention, the motor is so regulated that it does not require me>re power than the network can supply. At the same time, the magnitude of the torque required by the load and the magnitude of the torque generated by the motor are monitored, and the speed limit is set to a value corresponding to these magnitudes.
s, ~4~~,:: '. s ~~.~9!~~9
The object of the invention is to achieve an apparatus which enables an elevator motor to work even when the network voltage varies rapidly and even when the reduction in the voltage is relatively large. The apparatus has a frequency converter formed by a rectifier bridge, an inverter bridge, and an intermediate circuit between the rectifier bridge and the inverter bridge.
The apparatus also has voltage-measuring elements for the measurement of the voltage of the intermediate circuit, and further has a correction means for correcting the speed reference on the basis of a change in the voltage of the intermediate circuit. The frequency converter is used to produce from the frequency of a supply network connected to the rectifier bridge a frequency corresponding to a frequency reference depending on a speed reference for the motor. The speed of the motor is measured to form a speed feedback signal.
The apparatus may also comprise a limiter device which, based on the measured value of the voltage of the intermediate circuit, produces a coefficient by which the speed reference is multiplied in a multiplier element.
The apparatus may further comprise a memory and time-delay circuit which is designed to keep the coefficient at a constant value for a preset length of time.
The frequency converter may also comprise a torque regulator which additionally measures motor current. The torque developed by the motor is adjusted on the basis of the motor current, the frequency reference and the voltage of the intermediate circuit.
In the solution of the invention, the motor is so regulated that it does not require me>re power than the network can supply. At the same time, the magnitude of the torque required by the load and the magnitude of the torque generated by the motor are monitored, and the speed limit is set to a value corresponding to these magnitudes.
s, ~4~~,:: '. s ~~.~9!~~9
3 The apparatus for reducing the motor speed can be connected to a previously-installed frequency converter feeding a motor, which means that it can easily be added to a normal elevator system for the time required by the construction work without any changes in the elevator system itself. Due to the s use of a time-delay circuit, the elevator drive does not cause an unnecessary strain on the network in changeable load conditions. This allows a more secure and reliable supply of power to other construction-time working machines, such as cranes, etc.
In the course of elevator installation work, there often occur to unbalance conditions that are not encountered in normal elevator drives.
For example, the traction sheave of the elevator may have to sustain the whole mass of the counteivueight and to handle the resulting excessive torque. With the apparatus of the invention, the speed of rotation of the elevator motor is reduced correspondingly, and no excessive strain is placed on the supply 15 network. Ambient conditions, e.g. the temperature, may differ considerably from normal during construction, and involve an additional load on the elevator drive.
As the invention uses torque control, the effect is not reflected on the supply network.
A preferred embodiment of the invention is next described utilizing 2 o the accompanying drawing, in which:
Figure 1 is a schematic diagram of a motor and a connected power supply of the subjeca invention.
As illu;>trated by Figure 1, a three-phase a.c. elevator motor 10 is fed by a frequency converter 8 connected via phase conductors 2, 4 and 6 to 2s an electricity supply network. The frequency converter consists of a diode rectifier 12, a transistor-based inverter bridge 14, and d.c. conductors 16 and 18 connected between them. Connected between the d.c. conductors 16 and 18 is a capacitor 20.
The control of the motor speed is based on a speed reference and 3 o speed feedback. -fhe speed of the motor 10 is measured by means of a tachometer 22, whose measurement result V~ea~ is passed to a differential
In the course of elevator installation work, there often occur to unbalance conditions that are not encountered in normal elevator drives.
For example, the traction sheave of the elevator may have to sustain the whole mass of the counteivueight and to handle the resulting excessive torque. With the apparatus of the invention, the speed of rotation of the elevator motor is reduced correspondingly, and no excessive strain is placed on the supply 15 network. Ambient conditions, e.g. the temperature, may differ considerably from normal during construction, and involve an additional load on the elevator drive.
As the invention uses torque control, the effect is not reflected on the supply network.
A preferred embodiment of the invention is next described utilizing 2 o the accompanying drawing, in which:
Figure 1 is a schematic diagram of a motor and a connected power supply of the subjeca invention.
As illu;>trated by Figure 1, a three-phase a.c. elevator motor 10 is fed by a frequency converter 8 connected via phase conductors 2, 4 and 6 to 2s an electricity supply network. The frequency converter consists of a diode rectifier 12, a transistor-based inverter bridge 14, and d.c. conductors 16 and 18 connected between them. Connected between the d.c. conductors 16 and 18 is a capacitor 20.
The control of the motor speed is based on a speed reference and 3 o speed feedback. -fhe speed of the motor 10 is measured by means of a tachometer 22, whose measurement result V~ea~ is passed to a differential
4 element 24. The sipeed reference V~ef is obtained from the control equipment (not shown) of the elevator drive. By means of a multiplier 26, the speed reference is corrected by a factor determined by the voltage in the d.c.
circuit of the frequency converter. The corrected speed reference V~ef' is passed to the s differential element .24, which produces the difference between the values of the speed reference arid the real speed. Based on this difference, an amplifier device 28 further produces a frequency reference f~e, which is passed to the inverter bridge 14 ~~f the frequency converter 8 to control the transistors of bridge 14, as required by the reference.
to The d.c. circuit voltage U~ between conductors 16 and 18 is measured by a measuring circuit 17, and the measurement result is passed to a limiter circuit 30 which produces a scaled measurement value US. A memory circuit 32 stores the scaled voltage US and, based on this voltage, forms a coefficient k by which the speed reference V~ef is corrected in the multiplier 15 circuit 26. The memory circuit 32 is provided with a time-delay circuit to ensure that the speed reference correction term will not revert to a higher value during rapid voltage changes.
When the voltage U~ in the d.c. intermediate circuit falls, the corrected speed reference V~ef' produced by the multiplier circuit 26 falls, too.
2 o Uref is also reduced in comparison with the actual Speed V~ea~ measured by the tachometer, thus reducing the frequency reference f~ef from amplifier 28 and thus the elevator speed. In practice, the speed reduction can be implemented in a stepwise manner such that when the inverter intermediate circuit voltage falls by 5% from its nomiinal value, the maximum speed of the elevator is caused to 2 s reduce from a valuE~ of 2.5 m/s to a value of 1.6 m/s. Similarly, a 10%
voltage drop reduces the speed to 1.0 m/s, and a 15% voltage drop to 0.6 m/s. Speed curves corresponding with these values during acceleration and deceleration are stored beforehand in the memory of the elevator control system. The speed curves are so formed that the motor will not develop a torque exceeding the 3 o power supply capacity of the network at any stage during acceleration.
Therefore, the speed curve has a lower gradient during the initial acceleration
circuit of the frequency converter. The corrected speed reference V~ef' is passed to the s differential element .24, which produces the difference between the values of the speed reference arid the real speed. Based on this difference, an amplifier device 28 further produces a frequency reference f~e, which is passed to the inverter bridge 14 ~~f the frequency converter 8 to control the transistors of bridge 14, as required by the reference.
to The d.c. circuit voltage U~ between conductors 16 and 18 is measured by a measuring circuit 17, and the measurement result is passed to a limiter circuit 30 which produces a scaled measurement value US. A memory circuit 32 stores the scaled voltage US and, based on this voltage, forms a coefficient k by which the speed reference V~ef is corrected in the multiplier 15 circuit 26. The memory circuit 32 is provided with a time-delay circuit to ensure that the speed reference correction term will not revert to a higher value during rapid voltage changes.
When the voltage U~ in the d.c. intermediate circuit falls, the corrected speed reference V~ef' produced by the multiplier circuit 26 falls, too.
2 o Uref is also reduced in comparison with the actual Speed V~ea~ measured by the tachometer, thus reducing the frequency reference f~ef from amplifier 28 and thus the elevator speed. In practice, the speed reduction can be implemented in a stepwise manner such that when the inverter intermediate circuit voltage falls by 5% from its nomiinal value, the maximum speed of the elevator is caused to 2 s reduce from a valuE~ of 2.5 m/s to a value of 1.6 m/s. Similarly, a 10%
voltage drop reduces the speed to 1.0 m/s, and a 15% voltage drop to 0.6 m/s. Speed curves corresponding with these values during acceleration and deceleration are stored beforehand in the memory of the elevator control system. The speed curves are so formed that the motor will not develop a torque exceeding the 3 o power supply capacity of the network at any stage during acceleration.
Therefore, the speed curve has a lower gradient during the initial acceleration
5 stage. The nominal speed or other higher speed is restored by means of a RESET signal input to the time-delay circuit after the normal voltage has been permanently restorE~d, or when the voltage has remained at a higher value for a certain time since the last voltage drop.
The invention has been described above by the aid of one of its embodiments. However, the presentation is not to be regarded as constituting a limitation of the scope of patent protection, but the embodiments of the invention may vary within the limits defined by the following claims.
The invention has been described above by the aid of one of its embodiments. However, the presentation is not to be regarded as constituting a limitation of the scope of patent protection, but the embodiments of the invention may vary within the limits defined by the following claims.
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An apparatus for regulating the speed of an a.c. elevator motor, the apparatus comprising:
a frequency converter comprising:
a rectifier bridge;
an inverter bridge; and, an intermediate circuit between the rectifier bridge and the inverter bridge;
wherein the frequency converter is used for producing a frequency reference for the motor from the frequency of a supply network connected to the rectifier bridge;
a limiter device which, based on a measured value of a voltage of the intermediate circuit, produces a coefficient by which a motor speed reference signal is multiplied in a multiplier element to produce a corrected motor speed reference signal; and, a motor speed adjustment means that utilizes a measured motor speed to produce from the corrected motor speed reference signal an adjusted motor speed reference signal, the adjusted motor speed reference signal being used to adjust the frequency reference.
a frequency converter comprising:
a rectifier bridge;
an inverter bridge; and, an intermediate circuit between the rectifier bridge and the inverter bridge;
wherein the frequency converter is used for producing a frequency reference for the motor from the frequency of a supply network connected to the rectifier bridge;
a limiter device which, based on a measured value of a voltage of the intermediate circuit, produces a coefficient by which a motor speed reference signal is multiplied in a multiplier element to produce a corrected motor speed reference signal; and, a motor speed adjustment means that utilizes a measured motor speed to produce from the corrected motor speed reference signal an adjusted motor speed reference signal, the adjusted motor speed reference signal being used to adjust the frequency reference.
2. An apparatus as in claim 1, wherein the apparatus further comprises:
a memory and time-delay circuit which is designed to keep the coefficient at a constant value for a preset length of time.
a memory and time-delay circuit which is designed to keep the coefficient at a constant value for a preset length of time.
3. An apparatus as in claim 2, wherein the frequency converter also comprises a torque regulator which additionally measures motor current, and wherein the torque developed by the motor is adjusted on the basis of the motor current, the frequency reference and the voltage of the intermediate circuit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI942208A FI112737B (en) | 1994-05-11 | 1994-05-11 | Hardware for adjusting the lift motor |
| FIFI942208 | 1994-05-11 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2149009A1 CA2149009A1 (en) | 1995-11-12 |
| CA2149009C true CA2149009C (en) | 1999-12-28 |
Family
ID=8540684
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002149009A Expired - Fee Related CA2149009C (en) | 1994-05-11 | 1995-05-09 | Apparatus for regulating an elevator motor |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US5712457A (en) |
| EP (1) | EP0682405B1 (en) |
| JP (1) | JP3081505B2 (en) |
| CN (1) | CN1047893C (en) |
| AT (1) | ATE171020T1 (en) |
| AU (1) | AU686756B2 (en) |
| CA (1) | CA2149009C (en) |
| DE (1) | DE69504568T2 (en) |
| ES (1) | ES2122386T3 (en) |
| FI (1) | FI112737B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI123506B (en) | 2012-05-31 | 2013-06-14 | Kone Corp | Elevator control and elevator safety arrangement |
| CN103693517A (en) * | 2013-12-31 | 2014-04-02 | 江苏三上机电制造股份有限公司 | Frequency converting control system for building hoist and control method for frequency converting control system |
| WO2019123627A1 (en) * | 2017-12-22 | 2019-06-27 | 東芝三菱電機産業システム株式会社 | Motor drive device |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3961688A (en) * | 1974-04-29 | 1976-06-08 | Armor Elevator Company | Transportation system with malfunction monitor |
| JPH067754B2 (en) * | 1983-08-15 | 1994-01-26 | 株式会社日立製作所 | Induction motor controller |
| GB2168829B (en) * | 1984-12-21 | 1988-02-24 | Mitsubishi Electric Corp | Apparatus for controlling the speed of an elevator |
| JPS62107698A (en) * | 1985-10-31 | 1987-05-19 | Mitsubishi Electric Corp | Power interruption time stopping circuit for inverter |
| JPS62221897A (en) * | 1986-03-24 | 1987-09-29 | Mitsubishi Electric Corp | Motor control apparatus |
| US5089760A (en) * | 1986-12-10 | 1992-02-18 | Square D Company | DC bus voltage regulation by controlling the frequency in a variable frequency inverter |
| JPH0746918B2 (en) * | 1987-06-03 | 1995-05-17 | 株式会社日立製作所 | Power converter |
| US4926104A (en) * | 1989-10-18 | 1990-05-15 | General Electric Company | Adjustable speed AC drive system control for operation in pulse width modulation and quasi-square wave modes |
| FI86053C (en) * | 1989-10-31 | 1992-07-10 | Kone Oy | Method and apparatus for controlling a lifting motor |
| JPH06121404A (en) * | 1992-10-06 | 1994-04-28 | Hitachi Ltd | Apparatus of controlling electric rolling stock |
| US5373195A (en) * | 1992-12-23 | 1994-12-13 | General Electric Company | Technique for decoupling the energy storage system voltage from the DC link voltage in AC electric drive systems |
| JP2718001B2 (en) * | 1993-03-08 | 1998-02-25 | アレックス電子工業株式会社 | Power control device for induction motor |
-
1994
- 1994-05-11 FI FI942208A patent/FI112737B/en not_active IP Right Cessation
-
1995
- 1995-05-09 CA CA002149009A patent/CA2149009C/en not_active Expired - Fee Related
- 1995-05-10 ES ES95107082T patent/ES2122386T3/en not_active Expired - Lifetime
- 1995-05-10 AU AU17954/95A patent/AU686756B2/en not_active Ceased
- 1995-05-10 DE DE69504568T patent/DE69504568T2/en not_active Expired - Lifetime
- 1995-05-10 AT AT95107082T patent/ATE171020T1/en not_active IP Right Cessation
- 1995-05-10 US US08/438,554 patent/US5712457A/en not_active Expired - Lifetime
- 1995-05-10 EP EP95107082A patent/EP0682405B1/en not_active Expired - Lifetime
- 1995-05-11 CN CN95105799A patent/CN1047893C/en not_active Expired - Lifetime
- 1995-05-11 JP JP07135636A patent/JP3081505B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JP3081505B2 (en) | 2000-08-28 |
| JPH0847298A (en) | 1996-02-16 |
| CN1047893C (en) | 1999-12-29 |
| DE69504568T2 (en) | 1999-05-06 |
| FI112737B (en) | 2003-12-31 |
| AU1795495A (en) | 1995-11-16 |
| EP0682405B1 (en) | 1998-09-09 |
| FI942208A (en) | 1995-11-12 |
| ES2122386T3 (en) | 1998-12-16 |
| CA2149009A1 (en) | 1995-11-12 |
| ATE171020T1 (en) | 1998-09-15 |
| EP0682405A3 (en) | 1996-03-06 |
| EP0682405A2 (en) | 1995-11-15 |
| CN1121274A (en) | 1996-04-24 |
| DE69504568D1 (en) | 1998-10-15 |
| AU686756B2 (en) | 1998-02-12 |
| FI942208A0 (en) | 1994-05-11 |
| US5712457A (en) | 1998-01-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |