WO2012152586A2

WO2012152586A2 - Battery with at least one battery module string

Info

Publication number: WO2012152586A2
Application number: PCT/EP2012/057571
Authority: WO
Inventors: Stephan Rees; Holger Fink
Original assignee: Sb Limotive Germany Gmbh; Sb Limotive Company Ltd.
Priority date: 2011-05-06
Filing date: 2012-04-25
Publication date: 2012-11-15
Also published as: EP2705589A2; WO2012152586A3; DE102011075421A1

Abstract

What is introduced is: a battery (10) with at least one battery module string (70), in which the at least one battery module string (70) comprises a plurality of battery modules (40) connected in series. Each battery module (40) comprises at least one battery cell (41) and a coupling unit (30). The at least one battery cell (41) is connected between a first input (31) and a second input (32) of the coupling unit (30). The coupling unit (30) is designed to switch, in response to a first control signal, the at least one battery cell (41) between a first terminal (42) of the battery module (40) and a second terminal (43) of the battery module (40) and to connect, in response to a second control signal, the first terminal (42) to the second terminal (43). A centre tap (73) is arranged on the battery module string (70), with which centre tap a potential can be tapped off at a connection between two battery modules (40).

Description

Description title

Battery with at least one battery module string

The present invention relates to a battery having at least one

Battery module string, a drive system for an electric drive motor with the battery according to the invention and a motor vehicle with the

Drive system according to the invention.

State of the art

It is becoming apparent that in the future both in stationary applications, and in vehicles such as hybrid and electric vehicles increased

Battery systems will be used. To those for a respective

To meet given voltage requirements and available power, a large number of battery cells are connected in series. Since the power provided by such a battery must flow through all the battery cells and a battery cell can only conduct a limited current, battery cells are often additionally connected in parallel in order to increase the maximum current. This can be done either by providing multiple cell wraps within a battery cell housing or by externally interconnecting battery cells. It is, however

It is problematic that due to not exactly identical cell capacitances and voltages, there are equalizing currents between the parallel connected ones

Battery cells can come.

The block diagram of a conventional electric drive system, as used for example in electric and hybrid vehicles or in stationary applications such as in the rotor blade adjustment of wind turbines is shown in Figure 1. A battery 10 is connected to a DC voltage connected, which by a

Capacitor 1 1 is buffered. Connected to the DC voltage intermediate circuit is a pulse inverter 12, which is connected via two switchable semiconductor valves and two diodes at three outputs against each other

phase-shifted sinusoidal voltages for the operation of an electrical

Drive motor 13 provides. The capacitance of the capacitor 1 1 must be large enough to stabilize the voltage in the DC link for a period of time in which one of the switchable semiconductor valves is turned on. In a practical application such as an electric vehicle results in a high capacity in the range of mF. Because of the usually quite high voltage of the DC intermediate circuit such a large capacity can be realized only at high cost and with high space requirements.

FIG. 2 shows the battery 10 of FIG. 1 in a more detailed block diagram. A large number of battery cells are connected in series as well as optionally additionally in parallel, in order to achieve a high level of power for a particular application

Output voltage and battery capacity to achieve. Between the positive pole of the battery cells and a positive battery terminal 14, a charging and disconnecting device 16 is connected. Optionally, a separating device 17 can additionally be connected between the negative pole of the battery cells and a negative battery terminal 15. The separating and charging device 16 and the separating device 17 each include a contactor 18 or 19, which are provided, the battery cells of the battery terminals 14, 15th

to disconnect, to de-energize the latter. Due to the high DC voltage of the series-connected battery cells is otherwise significant risk potential for maintenance personnel or the like. In addition, a charging contactor 20 with a charging resistor 20 connected in series with the charging contactor 20 is provided in the charging and disconnecting device 16. The charging resistor 21 limits a charging current for the capacitor 1 1 when the battery is connected to the DC link. For this purpose, the contactor 18 is initially left open and only the charging contactor 20 is closed. When the voltage at the positive battery terminal 14 reaches the

Voltage of the battery cells, the contactor 18 can be closed and

if necessary, the charging contactor 20 are opened. The contactors 18, 19 and the charging contactor 20 increase the cost of a battery 10 is not insignificant because high demands are placed on their reliability and on the currents to be supplied by them.

The series connection of a large number of battery cells, in addition to the high total voltage, involves the problem that the entire battery fails if a single battery cell fails, because the battery current due to the

Series connection must be able to flow in all battery cells. Such a failure of the battery can lead to a failure of the entire system. At a

Electric vehicle leads to failure of the drive battery to a so-called

Lying, in other devices such as the

Rotor blade adjustment in wind turbines in strong winds can cause it

unwanted situations come. Therefore, high reliability of the

Battery advantageous. By definition, the term "reliability" means the

Ability of a system to work correctly for a given time.

Disclosure of the invention

According to the invention, therefore, a battery having at least one battery module string is introduced, in which at least one battery module string comprises a plurality of series-connected battery modules. The battery is preferably one

Lithium Ion Battery. Each battery module comprises at least one battery cell and a coupling unit. The at least one battery cell is connected between a first input and a second input of the coupling unit. The coupling unit is configured, in response to a first control signal, to switch the at least one battery cell between a first terminal of the battery module and a second terminal of the battery module and to connect the first terminal to the second terminal in response to a second control signal. At the battery module string a center tap is arranged, with which a potential at a connection between two battery modules can be tapped. Here, the two battery modules are adjacent in the series circuit.

The center tap may be in a middle of the plurality of series connected ones

Be arranged battery modules.

Several center taps may be arranged on the battery module string, with which a potential can be tapped off at a connection between in each case two battery modules. Here, each of the center taps is a pair of in the Serial circuit associated with adjacent battery modules. It is preferred that the center taps subdivide the battery module string such that each subdivision of the battery module string comprises an equal number of battery modules. The battery may include a control unit configured to apply the first control signal to a first variable number of battery modules of the at least one

Battery module string and the second control signal to the remaining

Issue battery modules of at least one battery module string and so set an output voltage of the at least one battery module string of the battery variable.

The coupling unit may have an output and be configured to connect to the first control signal either the first input or the second input to the output. The output is connected to the first terminal or to the second terminal of the battery module.

Another aspect of the invention relates to a drive system for an electric drive motor. The drive system includes a battery with a

Battery module string with multiple center taps and a multilevel inverter. The inputs of the multilevel inverter are connected to the center taps.

Another aspect of the invention relates to a motor vehicle with an electric drive motor for driving the motor vehicle. The electric drive motor is connected to the drive system according to the invention. drawings

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below, wherein like reference numerals designate like or functionally similar components. Show it:

1 shows an electrical drive system according to the prior art,

Figure 2 is a block diagram of a battery according to the prior art, Figure 3 is a coupling unit, which in a battery module string in the

battery according to the invention can be used, FIG. 4 shows a first embodiment of the coupling unit,

FIG. 5 shows a second embodiment of the coupling unit,

Figure 6 shows the second embodiment of the coupling unit in a simple

Semiconductor circuit,

FIGS. 7 and 8 show two arrangements of the coupling unit in a battery module,

FIG. 9 shows the coupling unit shown in FIG. 6 in the arrangement shown in FIG. 7,

FIG. 10 shows a first embodiment of the battery according to the invention,

Figure 1 1 a drive system for an electric drive motor with the battery according to the invention according to the first embodiment, and

Figure 12 shows a second embodiment of the battery according to the invention.

Embodiments of the invention

FIG. 3 shows a coupling unit 30 which can be used in a battery module string in the battery according to the invention. The coupling unit 30 has two inputs 31 and 32 and an output 33 and is adapted to connect one of the inputs 31 or 32 to the output 33 and to decouple the other. In certain embodiments of the coupling unit, this can also be formed, both inputs 31, 32 from the output 33rd

separate. However, it is not intended to connect both the input 31 and the input 32 to the output 33.

4 shows a first embodiment of the coupling unit 30, which has a changeover switch 34, which in principle can connect only one of the two inputs 31, 32 to the output 33, while the respective other input 31, 32 is disconnected from the output 33. The changeover switch 34 can be realized particularly simply as an electromechanical switch. FIG. 5 shows a second embodiment of the coupling unit 30, in which a first and a second switch 35 or 36 are provided. Each of the switches is connected between one of the inputs 31 and 32 and the output 33. In contrast to the embodiment of Figure 4, this embodiment has the advantage that both inputs 31, 32 from

Output 33 can be disconnected, so that the output 33 is high impedance. In addition, the switches 35, 36 can be easily used as semiconductor switches such as metal oxide semiconductor field effect transistor (MOSFET) switches or

Insulated Gate Bipolar Transistor (IGBT) switch can be realized.

Semiconductor switches have the advantage of a low price and a high switching speed, so that the coupling unit 30 can respond to a control signal or a change of the control signal within a short time and high switching rates can be achieved.

FIG. 6 shows the second embodiment of the coupling unit in a simple semiconductor circuit, in which each of the switches 35, 36 consists in each case of a semiconductor valve which can be switched on and off and a diode connected in parallel thereto.

FIGS. 7 and 8 show two arrangements of the coupling unit 30 in one

Battery module 40. A plurality of battery cells 41 is connected in series between the inputs of a coupling unit 30. However, the invention is not limited to such a series connection of battery cells, it can also be provided only a single battery cell or a parallel connection or mixed-serial-parallel circuit of battery cells. In the example of FIG. 7, the output of the coupling unit 30 is connected to a first terminal 42 and the negative pole of the battery cells 41 to a second terminal 43. However, it is possible a mirror image arrangement as in Figure 8, in which the positive pole of the battery cells 41 are connected to the first terminal 42 and the output of the coupling unit 30 to the second terminal 43.

FIG. 9 shows the coupling unit 30 shown in FIG. 6 in the arrangement shown in FIG. A control and diagnosis of the coupling units 30 via a signal line 44, which is connected to a control unit, not shown. FIG. 10 shows a battery 10 according to a first embodiment of the invention, which comprises a battery module string 70. The battery module string 70 consists of a plurality of series-connected battery modules 40, each having a

Coupling unit 30 include and as shown in Figure 7 or 8 are constructed. When assembling battery modules 40 to the battery module string 70, in each case the first terminal 42 of a battery module 40 is connected to the second terminal 43 of an adjacent battery module 40.

The battery module string 70 illustrated in FIG. 10 comprises six battery modules 40, which are connected between a negative pole 71 and a positive pole 72 of FIG

Battery module string 70 are connected. Arranged on the battery module string 70 are two center taps 73, with which a potential can be tapped off at a connection between in each case two battery modules 40 adjacent in the series connection. This means that each of the two center taps 73 is respectively connected to a first terminal 42 of a battery module 40 and to the second terminal 43 of an adjacent battery module 40.

The negative pole 71, the positive pole 72 and the center taps 73 of the battery module strand 70 together represent the taps of the battery 10. Because the battery modules 40 arranged between the taps each comprise coupling units 30, the output voltages which can be set at the taps are adjustable in stages.

The battery 10 includes a control unit, not shown, which is adapted to output to a variable number of battery modules 40, a first control signal through which the coupling units 30 of the thus controlled

Battery modules 40, the battery cell (or the battery cells) 41 between the first terminal 42 and the second terminal 43 of the respective battery module 40 switch. At the same time, the control unit outputs to the remaining battery modules 40 a second control signal, by which the coupling units 30 of these remaining battery modules 40 connect the first terminal 42 and the second terminal 43 of the respective battery module 40, whereby the battery cells 41 of this battery module 40 are bridged.

By suitable activation of the plurality of battery modules 40, different voltages can thus be output at the taps 71, 72, 73 of the battery 10. If, for example, the first control signal is output to the two battery modules arranged between the two center taps 73 of FIG. 10, the voltage between the two center taps 73 assumes the maximum adjustable value. If, on the other hand, the second control signal is output to the two battery modules 40, then a voltage 0 V is applied between the two center taps 73. If the first control signal is output to one of the two battery modules 40 and the second control signal is output to the other battery module, then there is between the two

Center taps 73 a single module voltage.

If more than two battery modules 40 are arranged between two adjacent taps 71, 72, 73 of the battery module string 70, a voltage is applied between them, which corresponds to the sum of the module voltages of those battery modules 40 to which the control unit outputs the first control signal.

By suitable choice of the switching states of the coupling units 30, the voltage between two taps 71, 72, 73 of the battery 10 can thus be adjusted in stages between 0 volts and the maximum value. The quantization steps in the

Adjustment of the output voltage correspond to the module voltages of the

Battery modules 40 and are thus of the number of battery cells 41 in the

Battery modules 40 and the state of charge of the battery cells 41 dependent.

The total output voltage between the negative pole 71 and the positive pole 72 of the battery module string 70 results from the summation of all partial voltages between adjacent taps of the battery module string 71, 72, 73.

The center taps 73 of the battery module string 70 shown in FIG. 10 subdivide it such that each subdivision of the battery module string 70 comprises two battery modules 40.

Figure 1 1 shows a drive system for an electric drive motor 13 with a battery 10 according to the first embodiment of the invention and a

Multilevel inverter 80. The multilevel inverter 80 has a plurality of inputs 81 and outputs 82 and is configured to output one of the potentials at each of its outputs 82, which is applied to one of its inputs 81. The outputs 82 of the multilevel inverter 80 are connected to inputs of the electrical Drive motor 13 connected. Since most available electric motors are designed for operation with three phase signals, the multilevel inverter 80 preferably has exactly three outputs 82. The inputs 81 of the multilevel inverter 80 are connected both to the center taps 73 and the poles 71, 72 of the battery 10 connected. By virtue of the fact that the potential at each of the outputs 82 of the multilevel inverters 80 is variable and depends on the potential values at its inputs 81 and the potential values applied to these inputs 81 are again selected by suitable means

Control of the battery modules 40 are adjustable in stages, there are several possible combinations of the control of the battery 10 and the multilevel inverter 80, which generate an equal phase signal at the outputs 82 of the multilevel inverter 80, for example, an approximately sinusoidal AC voltage.

FIG. 12 shows a second embodiment of the battery according to the invention in which only one center tap 73 is arranged in a center of four battery modules 40 connected in series.

With the invention described, it is possible to provide output voltages of a battery in several partial voltages, wherein the total voltage and the respective partial voltages are adjustable in stages and the reliability is significantly increased compared to systems according to the prior art.

Claims

claims

1 . Battery (10) having at least one battery module string (70), wherein the at least one battery module string (70) comprises a plurality of series-connected battery modules (40), characterized in that each battery module (40) at least one battery cell (41) and a coupling unit (30), wherein the at least one battery cell (41) connected between a first input (31) and a second input (32) of the coupling unit (30) and the coupling unit (30) is formed, in response to a first control signal at least one Battery cell (41) between a first terminal (42) of the battery module (40) and a second terminal (43) of the battery module (40) to switch and on a second control signal to the first terminal (42) with the second terminal (43) and wherein on the battery module string (70) a center tap (73) is arranged, with which a potential at a connection between two

Battery modules (40) can be tapped off.

The battery (10) of claim 1, wherein the center tap (73) is disposed in a center of the plurality of battery modules (40) connected in series.

3. Battery (10) according to claim 1 or 2, wherein on the battery module string (70) a plurality of center taps (73) are arranged, with which a potential at a connection between each two battery modules (40) can be tapped.

4. Battery (10) according to claim 3, wherein the Mittelabgriffe (73) the

Divide the battery module string (70) such that each subdivision of the battery module string (70) comprises an equal number of battery modules (40). A battery (10) according to any one of the preceding claims, wherein the battery (10) comprises a control unit and the control unit is adapted to apply the first control signal to a first variable number of battery modules (40) of the at least one battery module string (70) and the second control signal to output to the remaining battery modules (40) of the at least one battery module string (70) and thus to variably set an output voltage of the at least one battery module string (70) of the battery (10).

A battery (10) according to any one of the preceding claims, wherein the

Coupling unit (30) has an output (33) and is adapted to connect to the first control signal either the first input (31) or the second input (32) to the output (33), and wherein the output (33) is connected to the first terminal (42) or to the second terminal (43) of the battery module (40).

Drive system for an electric drive motor (13), wherein the

Drive system comprises a battery (10) according to one of claims 3 to 6 and a multilevel inverter (80) and wherein inputs of the

Multilevel inverter (80) are connected to the center taps (73).

A motor vehicle having an electric drive motor (13) for driving the motor vehicle and a drive system connected to the electric drive motor (13) according to claim 7.