JP2013021851A - Cell balancing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cell balancing apparatus that suppresses variations in output voltage between a plurality of battery cells constituting a main battery, and keeps mileage intact.SOLUTION: A cell balancing apparatus 1 includes: a cell balancing circuit 4 for equalizing output voltages of battery modules 19-1 to 19-n by developing a flow of current from a battery module 19 that outputs a voltage higher than an average voltage of the output voltages of the battery modules 19-1 to 19-n to a battery module 19 that outputs a voltage lower than the average voltage; and a DC/AC conversion circuit 6 for converting DC power supplied from a main battery 2 to AC power. When the DC/AC conversion circuit 6 converts DC power to AC power, a generator 3 applies currents to the battery modules 19-1 to 19-n via the cell balancing circuit 4.

Description

  The present invention relates to a cell balance device that equalizes voltages of a plurality of battery cells.

  A technique for realizing a high voltage battery by connecting a plurality of rechargeable battery cells in series has been put into practical use. In recent years, attention has been paid to this type of battery in mounting on, for example, an electric vehicle or a hybrid vehicle using both an engine and a motor (see, for example, Patent Document 1).

  However, when charging is performed in a state where a large number of battery cells are connected in series, the output voltage of each battery cell (or the remaining capacity of the battery) may become uneven. In addition, when the above-described battery is mounted on an electric vehicle or the like, since the discharge at the time of driving the motor and the charge at the time of regeneration are repeated, the voltage of the battery cell may become non-uniform even by repeating this charge / discharge. is there. And the nonuniformity of the voltage of a battery cell may accelerate | stimulate deterioration of some battery cells, and may cause the fall of efficiency as the whole battery. In addition, the nonuniformity of the voltage of a battery cell may arise by the manufacture dispersion | variation of each battery cell, aged deterioration, etc.

  Therefore, in order to eliminate variations in the output voltage of each battery cell as much as possible, for example, as a method of equalizing the output voltage of each battery cell (hereinafter referred to as cell balance), each battery cell is replaced with a transformer. There is a so-called active cell balance in which the output voltage of each battery cell is equalized by charging / discharging through the battery (see, for example, Patent Document 2).

  In addition, a main battery for vehicle traveling in which a plurality of battery cells are connected in series consumes power to charge an auxiliary battery for supplying power to electrical equipment such as a car navigation system, or an air conditioner. Power is consumed for driving. Thus, since the main battery for vehicle travel needs to supply electric power to other than the travel motor, if the power supply to other than the travel motor is increased, the travel distance may be reduced.

JP 2008-42970 A JP 2001-339865 A

  An object of the present invention is to provide a cell balance device capable of suppressing a decrease in travel distance while suppressing variations in output voltages of a plurality of battery cells constituting a main battery for vehicle travel.

  The cell balance device of the present invention is a battery module that outputs a voltage that is higher than the average voltage of the output voltages of the main battery, the generator, and the plurality of battery modules, each having a plurality of battery modules composed of one or more battery cells. A cell balance circuit that equalizes each output voltage of the plurality of battery modules by flowing current from the battery to a battery module that outputs a voltage lower than the average voltage, and direct current power supplied from the main battery is alternating current power A DC / AC conversion circuit that converts the power into a DC, and a control circuit that controls the operation of each of the cell balance circuit and the DC / AC conversion circuit. The control circuit converts DC power into AC in the DC / AC conversion circuit. When converting into electric power, the plurality of battery modules are supplied from the generator via the cell balance circuit. Each supplying power to.

  Thereby, the power supplied from the generator to the main battery can be used as AC power converted by the DC / AC conversion circuit. Thereby, since the power consumption of the main battery can be suppressed, the travelable distance can be extended.

  The main battery includes a first battery module and a second battery module, and the cell balance circuit includes a first transformer including first and second coils, and the first battery. A first switch provided between the module and the first coil; a second transformer having third and fourth coils; and between the second battery module and the third coil. A second switch provided; and a third switch provided between the second and fourth coils and the generator, wherein the control circuit converts DC power into AC in the DC / AC conversion circuit. When converting to electric power, the first and second switches may be turned on and off, respectively, and the third switch may be always turned on.

  Further, the control circuit may be configured to control the operation of the cell balance circuit so that the power supplied from the main battery is supplied to the auxiliary battery via the cell balance circuit.

  The cell balance circuit includes a fourth switch provided between the second and fourth coils and the auxiliary battery, and the control circuit supplies power supplied from the main battery to the cell balance. When supplying the auxiliary battery through a circuit, the first and second switches may be turned on and off, and the fourth switch may be turned on at all times.

  ADVANTAGE OF THE INVENTION According to this invention, in the cell balance apparatus which equalizes the voltage of the some battery cell which comprises a main battery, the fall of driving distance can be suppressed, suppressing the dispersion | variation in each output voltage of several battery cells. .

It is a figure which shows the cell balance apparatus of embodiment of this invention. It is a figure which shows an example of a cell balance circuit and a DC / AC conversion circuit. It is a figure which shows typically an example of the timing chart of ON / OFF of each switch. It is a figure which shows typically the other example of the timing chart of each switch ON / OFF.

FIG. 1 is a diagram showing a cell balance device according to an embodiment of the present invention.
A cell balance device 1 shown in FIG. 1 has a main battery 2 having a plurality of battery modules composed of one or more battery cells, a generator 3 (for example, a solar power generator, etc.), and an output voltage of each battery cell. A cell balance circuit 4 for equalization (hereinafter referred to as cell balance), a DC / AC conversion circuit 6, and a battery ECU (Electronic Control Unit) 5 for controlling the operation of the cell balance circuit 4 and the DC / AC conversion circuit 6 (control) Circuit). The battery ECU 5 is realized by a configuration including a processor and a memory, for example.

  The cell balance circuit 4 can charge each battery cell using the power supplied from the generator 3 during the cell balance. The DC / AC conversion circuit 6 converts DC power (for example, DC 200V) supplied from the main battery 2 into single-phase AC power (for example, AC 100V). The AC power converted by the DC / AC conversion circuit 6 is converted into three-phase AC power by the power conversion circuit 7 and supplied as driving power to the motor 8 constituting the compressor of the air conditioner. In addition, the cell balance circuit 4 can charge the auxiliary battery 9 (for example, a lead storage battery) with the power supplied from the main battery 2 after cell balance.

  In addition, the cell balance apparatus 1 of this embodiment shall be mounted in vehicles, such as a hybrid vehicle, a plug-in hybrid vehicle, an electric vehicle, or a forklift. When the main battery 2 is fully charged, the main battery 2 is charged with electric power supplied from the charging station 10 outside the vehicle via the charger 11. The power supplied from the main battery 2 to the bidirectional inverter circuit 12 is converted into three-phase AC power in the inverter circuit 12 and then supplied to the motor / generator 13 for driving as driving power. Shall be. Moreover, the voltage of one battery cell at the time of full charge, the voltage of the auxiliary battery 9 at the time of full charge, and the output voltage of the generator 3 are set to the same voltage (for example, 12-14V), respectively. Shall be. Further, the auxiliary battery 9 is connected to, for example, an electric equipment 14 such as a car navigation system and a motor ECU 15 that controls the operation of the motor / generator 13 and an inverter ECU 16 that controls the operation of the inverter circuit 12 via a DC / DC converter 17. Power supply.

  Thus, since the cell balance apparatus 1 of this embodiment is provided with the cell balance circuit 4, it can suppress the dispersion | variation in each output voltage of each battery cell of the main battery 2. FIG.

  Further, since the cell balance device 1 of the present embodiment includes the DC / AC conversion circuit 6, it is possible to supply single-phase AC power to the power conversion circuit 7 using the main battery 2. Therefore, when charging each battery cell using power supplied from the generator 3 during cell balance, when supplying single-phase AC power to the power conversion circuit 7, the main battery is supplied from the generator 3 to the main battery. The power supplied to 2 can be used as AC power converted by the DC / AC conversion circuit 6. Thereby, since the power consumption of the main battery 2 at the time of use of an air conditioner can be suppressed, the travelable distance can be extended.

  Further, since the cell balance device 1 of the present embodiment can charge the auxiliary battery 9 with the electric power supplied from the main battery 2 via the cell balance circuit 4, the voltage of the main battery 2 is stepped down to compensate. It is not necessary to additionally provide a DC / DC converter or the like for outputting to the machine battery 9, and an increase in physique can be suppressed. When power is supplied to the auxiliary battery 9 after charging the main battery 2 with the power from the generator 3, the power charged to the main battery 2 should be used as power supplied to the auxiliary battery 9. Can do. Thereby, since the power consumption of the main battery 2 at the time of use of an air conditioner can be suppressed, the travelable distance can be extended.

  FIG. 2 is a diagram illustrating an example of the cell balance circuit 4 and the DC / AC conversion circuit 6. The main battery 2 includes n battery modules 19 (batteries) composed of three battery cells 18 (for example, secondary batteries such as a lithium ion secondary battery and a nickel hydride secondary rechargeable battery) connected in series. Module 19-1 (first battery module), battery module 19-2 (second battery module),..., And battery module 19-n (nth battery module) are connected in series. Shall be. The number of battery cells 18 constituting one battery module 19 is not limited to three. Moreover, the negative electrode terminal of the main battery 2 shall be connected to the virtual ground connected to the vehicle body etc., for example.

  The cell balance circuit 4 shown in FIG. 2 includes voltage sensors 20-1 to 20-n. The voltage sensors 20-1 to 20-n are connected to the positive terminal and the negative terminal of the battery modules 19-1 to 19-n, respectively. The voltage sensors 20-1 to 20-n detect the output voltages Vdet (1) to Vdet (n) of the battery modules 19-1 to 19-n, respectively.

  Further, the cell balance circuit 4 shown in FIG. 2 includes one transformer T and four switches SW for each of the battery modules 19-1 to 19-n. Each switch SW may be configured by, for example, an ASIC (Application Specific Integrated Circuit).

  The cell balance circuit 4 shown in FIG. 2 includes switches 21-1 and 21-2 (third switch) and switches 22-1 and 22-2 (fourth switch). Note that the switches 21-1 and 21-2 and the switches 22-1 and 22-2 may be configured by switching elements such as relays or MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

  For example, for the battery module 19-1, a transformer T1 (first transformer) and switches SW-1a (first switch), SW-1b (first switch), SW-1c, and SW-1d are provided. Is provided. For the battery module 19-2, a transformer T2 (second transformer) and switches SW-2a (second switch), SW-2b (second switch), SW-2c, and SW-2d are provided. ing. The same applies to the other battery modules 19-3 to 19-n. The first terminal of the first coil of the transformer T1 is electrically connected to the positive terminal of the battery module 19-1 via the switch SW-1a. The second terminal of the first coil of the transformer T1 is electrically connected to the negative terminal of the battery module 19-1 via the switch SW-1b. The switch SW-1c is electrically connected to the first terminal of the second coil of the transformer T1, and the switch SW-1d is electrically connected to the second terminal of the second coil of the transformer T1. The other transformers T2 to Tn have the same configuration. The first coil is one of the primary coil and the secondary coil, and the second coil is the other of the primary coil and the secondary coil. In the transformers T1 to Tn, the winding ratio between the first coil and the second coil is not particularly limited, but is, for example, 1: 1.

  Each switch SW-1c, SW-2c, SW-3c,. . . , SW-nc are electrically connected to each other, are connected to the positive terminal of the generator 3 via the switch 21-1, and are connected to the rectifier 23 via the switch 22-1 and are output from the rectifier 23. Is connected to the positive terminal of the auxiliary battery 9. Each switch SW-1d, SW-2d, SW-3d,. . . , SW-nd are electrically connected to each other, connected to the negative terminal of the generator 3 via the switch 21-2, and connected to the rectifier 23 via the switch 22-2. Is connected to the negative terminal of the auxiliary battery 9.

  The switches SW-1a to SW-na and the switches SW-1b to SW-nb are turned on and off by a control signal CELS generated by the battery ECU 5, respectively. Note that the duty of the control signal CELS is, for example, 50%. For example, when the switch SW-1a and the switch SW-1b are turned on, the first coil of the transformer T1 is connected in parallel to the battery module 19-1. The same applies to the switches SW-2a to SWna and the switches SW-2b to SW-nb. Also, the switches SW-1c to SW-nc and the switches SW-1d to SW-nd are turned on and off by a control signal CEL generated by the battery ECU 5, respectively. Note that the duty of the control signal CEL is, for example, 50%. For example, when the switches SW-1c to SW-nc and the switches SW-1d to SW-nd are turned on, the second coils of the transformers T1 to Tn are connected in parallel to each other. At this time, when the switches 21-1 and 21-2 are turned on by the control signal GEN generated by the battery ECU 5, the second coils of the transformers T1 to Tn and the generator 3 are electrically connected. Alternatively, when the switches 22-1 and 22-2 are turned on by the control signal BAT generated by the battery ECU 5, the second coils of the transformers T1 to Tn and the auxiliary battery 9 are electrically connected.

  The DC / AC conversion circuit 6 shown in FIG. 2 includes transformers Tac1 and Tac2 and switches SWac1 and SWac2 for the entire main battery 2. That is, the first terminal of the first coil of the transformer Tac1 is connected to the negative terminal of the main battery 2 via the switch SWac1, and the second terminal of the first coil of the transformer Tac1 is connected to the positive terminal of the main battery 2. ing. The first terminal of the second coil of the transformer Tac1 is connected to one input terminal of the power conversion circuit 7, and the second terminal of the second coil of the transformer Tac1 is the first terminal of the second coil of the transformer Tac2. It is connected to the. The first terminal of the first coil of the transformer Tac2 is connected to the positive terminal of the main battery 2, and the second terminal of the first coil of the transformer Tac2 is connected to the negative terminal of the main battery 2 via the switch SWac2. ing. The second terminal of the second coil of the transformer Tac2 is connected to the other input terminal of the power conversion circuit 7. The first coil is one of the primary coil and the secondary coil, and the second coil is the other of the primary coil and the secondary coil. Further, the winding ratio of the first and second coils in the transformer Tac1 and the winding ratio of the first and second coils in the transformer Tac2 are not particularly limited, but are 2: 1, for example. Further, the winding ratio of the first coil of the transformer Tac1 and the first coil of the transformer Tac2 and the winding ratio of the second coil of the transformer Tac1 and the second coil of the transformer Tac2 are not particularly limited. 1: 1. Further, the transformers Tac1 and Tac2 of the DC / AC conversion circuit 6 and the transformers T1 to Tn of the cell balance circuit 4 may be provided in one unit, or may be provided in separate units. Good.

  The switch SWac1 is turned on / off by a control signal AC1 generated by the battery ECU 5. The switch SWac2 is turned on / off by a control signal AC2 generated by the battery ECU 5. The duty of each of the control signals AC1 and AC2 is 50%, for example. For example, when the switch SWac1 is turned on and the switch SWac2 is turned off, a current flows from the second terminal of the first coil of the transformer Tac1 to the first terminal, and from the second terminal of the second coil of the transformer Tac1 to the first terminal. The flowing current flows to the power conversion circuit 7. When the switch SWac1 is turned off and the switch SWac2 is turned on, a current flows from the first terminal of the first coil of the transformer Tac2 to the second terminal, and from the first terminal of the second coil of the transformer Tac2 to the second terminal. The flowing current flows to the power conversion circuit 7. As described above, when the switches SWac1 and SWac2 are alternately turned on and off, a single-phase alternating current flows from the transformers Tac1 and Tac2 to the power conversion circuit 7.

  FIG. 3 is a diagram schematically illustrating an example of an on / off timing chart of each switch of the cell balance circuit 4 and the DC / AC converter circuit 6. When the control signal BAT is at a high level, the switches 22-1 and 22-2 are turned on. When the control signal BAT is at a low level, the switches 22-1 and 22-2 are turned off. . In addition, when the control signal GEN is at a high level, the switches 21-1 and 21-2 are turned on. When the control signal GEN is at a low level, the switches 21-1 and 21-2 are turned off. . When the control signal CEL is at a high level, the switches SW-1c to SW-nc and the switches SW-1d to SW-1d are turned on. When the control signal CEL is at a low level, the switches SW-1c to SW-nc And switches SW-1d to SW-nd are turned off. When the control signal CELS is at a high level, the switches SW-1a to SW-na and the switches SW-1b to SW-nb are turned on. When the control signal CELS is at a low level, the switches SW-1a to SW-na. And switches SW-1b to SW-nb are turned off. Further, it is assumed that the switch SWac1 is turned on when the control signal AC1 is at a high level, and the switch SWac1 is turned off when the control signal AC1 is at a low level. Further, the switch SWac2 is turned on when the control signal AC2 is at a high level, and the switch SWac2 is turned off when the control signal AC2 is at a low level.

  In the example shown in FIG. 3, in the periods T1 to T4, the switches SWac1 and SWac2 are alternately turned on and off by the control signals AC1 and AC2. As described above, when the switches SWac1 and SWac2 are alternately turned on and off, AC power is supplied from the DC / AC conversion circuit 6 to the power conversion circuit 7.

  In the example shown in FIG. 3, the switches SW-1a to SW-na and the switches SW-1b to SW-nb are turned on and off by the control signal CELS in the periods T2 to T3 in the periods T1 to T4, The switches SW-1c to SW-nc and the switches SW-1d to SW-1d are always turned on by the control signal CEL, and the switches 21-1 and 21-2 are always turned on by the control signal GEN. Then, an alternating current flows through each of the first coils of the transformers T1 to Tn, and the first coil and the second coil of the transformers T1 to Tn are electromagnetically coupled to each other. At this time, for example, when the voltage of the first coil of the transformer T1 is higher than the output voltage of the battery module 19-1, a current flows from the first coil of the transformer T1 to the battery module 19-1, and the battery module 19 -1 is charged. For example, when the voltage of the first coil of the transformer T2 is lower than the output voltage of the battery module 19-2, a current flows from the battery module 19-2 to the first coil of the transformer T2, and the battery module 19- 2 is discharged. And by each charging / discharging of battery module 19-1 to 19-n, each output voltage of battery module 19-1 to 19-n becomes the average of each output voltage of battery module 19-1 to 19-n. When the voltage settles, that is, when the output voltages of the battery modules 19-1 to 19-n become substantially the same voltage, each switch SW is turned off to terminate the cell balance. At this time, if the voltage of the generator 3 is higher than the voltage of each of the second coils of the transformers T1 to Tn, current flows from the generator 3 to each of the second coils of the transformers T1 to Tn. Almost the same current that flows through each second coil flows through each first coil of the transformers T1 to Tn. That is, current flows from the generator 3 to the battery modules 19-1 to 19-n via the transformers T1 to Tn, and the battery modules 19-1 to 19-n are charged, respectively. In this manner, the battery modules 19-1 to 19-n can be charged while equalizing the output voltages of the battery modules 19-1 to 19-n, respectively. Then, AC power can be supplied from the DC / AC conversion circuit 6 to the power conversion circuit 7 using the power supplied to the main battery 2.

  FIG. 4 is a diagram schematically illustrating another example of an on / off timing chart of each switch of the cell balance circuit 4 and the DC / AC conversion circuit 6. In the example shown in FIG. 4, the periods T1 to T4 are the same as the periods T1 to T4 in the example shown in FIG.

  In the example shown in FIG. 4, in the period T5 to T6, the switches SW-1a to SW-na and the switches SW-1b to SW-nb are turned on and off by the control signal CELS, respectively, and the switches SW-1c to SW are turned on by the control signal CEL. −nc and the switches SW-1d to SW-1d are always on, and the switches 21-1 and 21-2 are always on according to the control signal GEN. Accordingly, as described above, the battery modules 19-1 to 19-n can be charged while equalizing the output voltages of the battery modules 19-1 to 19-n, respectively.

  Next, in the example shown in FIG. 4, in the periods T6 to T7, the switches SW-1a to SW-na and the switches SW-1b to SW-nb are turned on and off by the control signal CELS, respectively, and the switch SW- 1c to SW-nc and switches SW-1d to SW-1d are always on, and the switches 22-1 and 22-2 are always on according to the control signal BAT. The switches 21-1 and 21-2 are always off. At this time, for example, if the voltage of each of the second coils of the transformers T1 to Tn is higher than the voltage of the auxiliary battery 9, current flows from each of the second coils of the transformers T1 to Tn to the auxiliary battery 9. Thus, the auxiliary battery 9 is charged.

  As described above, during the cell balance, the main battery 2 is charged with the power supplied from the generator 3, and then the auxiliary battery 9 is charged with the power supplied from the main battery 2. The auxiliary battery 9 can be charged using the electric power supplied to the battery 2.

  In the above-described embodiment, at the time of cell balancing, the output voltages Vdet (1) to Vdet (n) of the battery modules 19-1 to 19-n are the upper limit threshold Vth1 (battery modules 19-1 to 19-n Lower than the lower limit threshold Vth2 (a value lower than the average value of the respective output voltages of the battery modules 19-1 to 19-n). The switches SW-1a to SW-na and the switches SW-1b to SW-nb may be turned on and off, respectively, until they become higher.

  Moreover, in the said embodiment, although it is the structure which equalizes each output voltage of the battery modules 19-1 to 19-n by charging / discharging all the battery modules 19-1 to 19-n simultaneously, the battery module 19 The output voltages of the battery modules 19-1 to 19-n may be equalized by charging and discharging the battery modules 19 in order of two of -1 to 19-n.

  In the above embodiment, the power supplied from each of the battery modules 19-1 to 19-n is used when the auxiliary battery 9 is charged. However, when the auxiliary battery 9 is charged, the battery module 19 is used. You may make it use the electric power supplied from the one part battery module 19 among -1-19-n.

DESCRIPTION OF SYMBOLS 1 Cell balance apparatus 2 Main battery 3 Generator 4 Cell balance circuit 5 Battery ECU
6 DC / AC conversion circuit 7 Power conversion circuit 8 Motor 9 Auxiliary battery 10 Charging stand 11 Charger 12 Inverter circuit 13 Motor / generator 14 Electrical equipment 15 Motor ECU
16 Inverter ECU
17 DC / DC converter 18 Battery cell 19 Battery module 20 Voltage sensor 21, 22 Switch 23 Rectifier

Claims (4)

A main battery having a plurality of battery modules composed of one or more battery cells;
A generator,
Output of each of the plurality of battery modules by flowing current from the battery module that outputs a voltage higher than the average voltage of the output voltages of the plurality of battery modules to the battery module that outputs a voltage lower than the average voltage. A cell balance circuit for equalizing the voltage;
A DC / AC conversion circuit for converting DC power supplied from the main battery into AC power;
A control circuit for controlling the operations of the cell balance circuit and the DC / AC converter circuit;
With
The control circuit supplies power to each of the plurality of battery modules from the generator via the cell balance circuit when converting DC power into AC power in the DC / AC converter circuit. Balance device. The cell balance device according to claim 1,
The main battery has a first battery module and a second battery module,
The cell balance circuit includes a first transformer having first and second coils, a first switch provided between the first battery module and the first coil, and third and fourth. A second transformer having a second coil, a second switch provided between the second battery module and the third coil, and between the second and fourth coils and the generator. A third switch provided,
The control circuit turns on and off the first and second switches and always turns on the third switch when converting DC power into AC power in the DC / AC conversion circuit. Cell balance device. The cell balance control circuit according to claim 1,
The cell balance device, wherein the control circuit controls an operation of the cell balance circuit so that electric power supplied from the main battery is supplied to the auxiliary battery via the cell balance circuit. The cell balance control circuit according to claim 2,
The cell balance circuit includes a fourth switch provided between the second and fourth coils and the auxiliary battery,
When the control circuit supplies power supplied from the main battery to the auxiliary battery via the cell balance circuit, the control circuit turns on and off the first and second switches, respectively, A cell balance device characterized by always turning on a switch.