WO2013125299A1 - Cell-balance device and battery system - Google Patents

Description

Cell balance device and battery system

The present invention relates to a cell balance device and a battery system that balance cells of secondary batteries connected in series, and particularly to a cell balance device and a battery system that can prevent a switch circuit of the cell balance device from being destroyed by an overcurrent. About.

Fig. 5 shows a circuit diagram of a conventional cell balance adjustment circuit. A cell balance device having a conventional cell balance adjustment circuit includes an assembled battery portion in which a plurality of basic secondary battery cells (hereinafter referred to as cells) 401 to 406 are connected in series, and one of the connection portions of each cell. Switches 411 to 462 to which contacts are connected are provided. The other contact of the switches 411, 421, 431, 441, 451, 461 is connected to one electrode of the capacitor 407, which is a voltage holding device, and is not the cell side of the switch 412, 422, 432, 442, 452, 462. Is connected to the other electrode of the voltage holding device 407. A load circuit or a charging circuit 408 is connected to both ends of the assembled battery.

The open / close signal of each switch is connected so that the switch 411 and the switch 412 operate simultaneously. Similarly, the switch 421 and the switch 422, the switch 431 and the switch 432, the switch 441 and the switch 442, the switch 451 and the switch 452, and the switch 461 and the switch 462 are simultaneously opened and closed as a set of two switches. Such a signal is connected. Further, the switch open / close signal turns on / off the switch 411 and the switch 412 → turns on and off the switch 421 and the switch 422 → turns on and off the switch 431 and the switch 432 → turns on and off the switch 441 and the switch 442 → turns on and off the switch 451 and the switch 452 → The switch 462 is turned on and off, and the connection is sequentially turned on and off. When the on / off of the switch 461 and the switch 462 is finished, the operation returns to the on / off operation of the first switch 411 and the switch 412 and an open / close signal for continuously opening / closing the switch is connected to the control unit of each switch.

Next, the operation will be described. By sequentially switching the switches in one direction while forming a parallel connection between adjacent cells connected in series and the voltage holding device 407, all the cells connected in series and the voltage holding device 407 A parallel connection is sequentially formed between the two. Then, after completing the formation of parallel connection with all the cells in the battery pack to be controlled, the cell balance is adjusted by returning to the first cell and repeating the same switching operation.

The switches 411 and 412 are configured to receive signals for opening and closing simultaneously, and the switches 421 and 422 are also configured to open and close simultaneously. Similarly, the switch 431 and the switch 432, the switch 441 and the switch 442, the switch 451 and the switch 452, and the switch 461 and the switch 462 are simultaneously opened and closed. After the switch 411 and the switch 412 are opened and closed sequentially, and the switch 461 and the switch 462 are opened and closed, the switch 411 and the switch 412 are opened and closed again, and this operation is sequentially repeated. When the balance state is maintained in all the cells and the cell voltages are the same, no charge is transferred between the voltage holding circuit 407 and the cells. Even if each switch is opened and closed, the state of each cell is not affected. On the other hand, when the cell is out of balance, the balance adjustment function is exhibited.

JP 2001-178008 A

However, the conventional technique has a problem that the reliability of the cell balance device is lowered due to an overcurrent flowing through the switch.

In order to solve the conventional problems, the cell balance device of the present invention has the following configuration.

A cell balance device constituting a battery system that adjusts the cell balance of a plurality of capacitors connected in series, a plurality of capacitor connection terminals to which connection points or both ends of the plurality of capacitors connected in series are connected, and A voltage holding device connection terminal to which the voltage holding device is connected, a plurality of first switch circuits provided between the plurality of capacitor connection terminals and the voltage holding device, a receiving terminal for receiving a synchronization signal, and a synchronization signal A transmission terminal for transmitting, a control circuit for controlling on / off of the plurality of first switch circuits based on the synchronization signal, and an overcurrent detection circuit for detecting an overcurrent flowing through the first switch circuit. A cell balance device.

In addition, a plurality of capacitors connected in series, a plurality of voltage holding devices connected in series, a clock generation circuit that outputs a synchronization signal, and a plurality of connection points or both ends of the plurality of capacitors connected in series A battery system comprising: a plurality of voltage holding device connection points or a plurality of cell holding devices connected to a voltage holding device connection terminal connected to a capacitor connection terminal and connected in series.

According to the present invention, when the overcurrent flows through the switch circuit, a battery device with high safety can be configured by detecting the overcurrent and turning off the switch circuit.

It is a circuit diagram of the battery system provided with the cell balance apparatus of this embodiment. It is a circuit diagram of the cell balance apparatus of this embodiment. It is the figure which showed the timing chart of the signal of the cell balance apparatus of this embodiment. It is a circuit diagram of the overcurrent detection circuit of the cell balance apparatus of this embodiment. It is a circuit diagram of the cell balance apparatus provided with the conventional cell balance adjustment circuit.

<First Embodiment>
FIG. 1 is a circuit diagram of a battery system including the cell balance device of the present embodiment. FIG. 2 is a circuit diagram of the cell balance device of the present embodiment. FIG. 4 is a circuit diagram of an overcurrent protection circuit of the cell balance device of this embodiment.

The battery system 10 of the present embodiment includes a clock generation circuit 102, n + 1 secondary batteries A1 to An + 1 connected in series, n cell balance devices B1 to Bn, and n−1 voltage holding devices (capacitors) C1. ˜Cn−1 and an external terminal to which a charger 101 and a load are connected (n is an integer of 2 or more).

The first cell balance device B1 includes switch circuits S11, S21, S31, a control circuit 201, overcurrent detection circuits 211, 221, 231 and terminals T11, T21, T31, T41, T51, T61. Yes. The same applies to the other cell balance devices B2 to Bn. The overcurrent detection circuit 231 includes a comparator 503, a constant current circuit 502, and a switch circuit 501. Other overcurrent detection circuits are similarly configured.

In the cell balance device B1, the terminal T11 is connected to the negative electrode of the secondary battery A1, the terminal T21 is connected to the positive electrode of the secondary battery A1 and the terminal T12 of the cell balance device B2, and the terminal T31 is connected to the positive electrode of the secondary battery A2. The cell balance device B2 is connected to the terminal T22, the terminal T41 is connected to one terminal of the voltage holding device C1, the terminal T51 is connected to the output of the clock generation circuit 102, and the terminal T61 is connected to the terminal T52 of the cell balance device B2. Connected. In the cell balance device B2, the terminal T22 is connected to the terminal T13 of the cell balance device B3, the terminal T32 is connected to the positive electrode of the secondary battery A3 and the terminal T23 of the cell balance device B3, and the terminal T42 is one of the voltage holding devices C2. And the other terminal of the voltage holding device C1, and the terminal T62 is connected to the terminal T53 of the cell balance device B3. The connection to the (n-1) th cell balance device Bn-1 is made in the same manner as the cell balance device B2. In the cell balance device Bn, the terminal T1n is connected to the negative electrode of the secondary battery An, the terminal T2n is connected to the positive electrode of the secondary battery An and the terminal T3n-1 of the cell balance device Bn-1, and the terminal T3n is connected to the secondary battery. It is connected to the positive electrode of An + 1, and the terminal T4n is connected to the voltage holding device Cn-1.

In the cell balance device B1, the switch circuit S11 is connected to the terminals T11 and T41, the switch circuit S21 is connected to the terminals T21 and T41, and the switch circuit S31 is connected to the terminals T31 and T41. The input of the overcurrent detection circuit 211 is connected to both ends of the switch circuit S11, and the output is connected to the control circuit 201. The input of the overcurrent detection circuit 221 is connected to both ends of the switch circuit S21, and the output is connected to the control circuit 201. The input of the overcurrent detection circuit 231 is connected to both ends of the switch circuit S31, and the output is connected to the control circuit 201. The switch circuits S11, S21, and S31 are on / off controlled by a signal from the control circuit 201. The other cell balance devices B2 to Bn are similarly connected.

In the overcurrent detection circuit 231, the terminal T41 is connected to the non-inverting input terminal of the comparator 503, the switch circuit 501 and the constant current circuit 502 are connected to the inverting input terminal, and the control circuit 201 is connected to the output terminal. The other end of the switch circuit 501 is connected to the terminal T31, and the other end of the constant current circuit 502 is connected to the negative electrode of the secondary battery A1. The switch circuits S31 and 501 are simultaneously turned on and off by inputting a signal from the control circuit 201. Other overcurrent detection circuits are similarly connected.

Next, the operation of the battery system 10 of this embodiment will be described. FIG. 3 is a diagram showing a signal timing chart of the cell balance device of the present embodiment.

When the charger 101 is connected to the external terminal of the battery system 10 at time t0, the clock generation circuit 102 outputs the clock signal CLK. When the cell balance device B1 receives the clock signal CLK at the terminal T51, the control circuit 201 generates signals that turn on the switch circuits S11 to S31 in synchronization with the clock signal CLK, and sequentially outputs them. Further, the control circuit 201 outputs the clock signal CLK to the terminal T61. The next cell balance device B2 receives the clock signal CLK from the cell balance device B1 at the terminal T52. In this way, the clock signal CLK is transmitted to the cell balance device Bn, and all the cell balance devices B1 to Bn can be synchronized. Accordingly, the switch circuits S11 to S1n, the switch circuits S21 to S2n, and the switch circuits S31 to S3n are controlled to be sequentially turned on in synchronization.

At time t1, when all the switch circuits S11 to S1n are turned on and all the switch circuits S21 to S2n and the switch circuits S31 to S3n are turned off, the secondary batteries A1 to An-1 are in parallel with the voltage holding devices C1 to Cn-1, respectively. Connected. Then, the secondary batteries A1 to An-1 and the voltage holding devices C1 to Cn-1 are discharged or charged, respectively.

At time t2, when all the switch circuits S21 to S2n are turned on and all the switch circuits S11 to S1n and the switch circuits S31 to S3n are turned off, the secondary batteries A2 to An are connected in parallel with the voltage holding devices C1 to Cn-1, respectively. The The secondary batteries A2 to An and the voltage holding devices C1 to Cn-1 are discharged or charged, respectively.

At time t3, when switch circuits S31 to S3n are all turned on and switch circuits S11 to S1n and switch circuits S21 to S2n are all turned off, secondary batteries A3 to An + 1 are connected in parallel with voltage holding devices C1 to Cn-1, respectively. The The secondary batteries A3 to An + 1 and the voltage holding devices C1 to Cn-1 are discharged or charged, respectively.

And all the cell balance devices B1 to Bn repeat the same operation with 3 clocks as one cycle.

When the charger 101 is disconnected from the external terminal of the battery system 10, the clock generation circuit 102 stops outputting the clock signal CLK and ends the cell balance operation.

In this way, by repeating charging and discharging between the secondary batteries A1 to An + 1 and the voltage holding devices C1 to Cn-1, the voltages of the secondary batteries A1 to An + 1 can be averaged to reduce voltage variation. it can. And since it was set as the structure provided with the several voltage holding | maintenance apparatus according to the number of the secondary batteries which should be balanced, the balance capability of a cell balance apparatus can be made high (the speed which balances can be made quick).

When the terminals T21 and T41 are short-circuited with all the switch circuits S31 to S3n turned on, a current flows from the secondary battery A2 via the switch circuit S31. At this time, the switch circuit 501 is also turned on at the same time, current flows from the constant current circuit 502, and the voltage at the inverting input terminal of the comparator 503 drops due to the ON resistance of the switch circuit 501, and maintains a constant voltage. When the current continues to flow through the switch circuit S31 and the voltage at the non-inverting input terminal of the comparator 503 falls below the voltage at the inverting input terminal, the comparator 503 outputs a Lo signal. The control circuit 201 receives this signal and turns off the switch circuit S31. In this way, it is possible to stop the overcurrent from flowing from the secondary battery A2 via the switch circuit S31 and to prevent the switch circuit S31 from being destroyed.

The on-resistance RonS31 of the switch circuit S31 and the on-resistance Ron501 of the switch circuit 501 are set so that RonS31 ÷ Ron501 = N (constant). Assuming that the overcurrent detection current is Ioc and the current of the constant current circuit 502 is Iref, Iref = Ioc × RonS31 ÷ Ron501 is set. The overcurrent detection current Ioc can be set by adjusting the current value and temperature characteristics of the constant current Iref and the on-resistance and temperature characteristics of the switch circuit 501. For example, if the on-resistance Ron 501 is set so that N is 0.001, the constant current Iref may be 1/1000 of the overcurrent detection current Ioc, and when the switch circuit 501 is configured by a MOS transistor, the switch circuit S31 Smaller size is acceptable.

When the terminals T11 and T41 are short-circuited with all the switch circuits S31 to S3n turned on, current flows from the secondary batteries A1 and A2 through the switch circuit S31. At this time, the switch circuit 501 is also turned on at the same time, current flows from the constant current circuit 502, and the voltage at the inverting input terminal of the comparator 503 drops due to the ON resistance of the switch circuit 501, and maintains a constant voltage. When the current continues to flow through the switch circuit S31 and the voltage at the non-inverting input terminal of the comparator 503 falls below the voltage at the inverting input terminal, the comparator 503 outputs a Lo signal. The control circuit 201 receives this signal and turns off the switch circuit S31. In this way, it is possible to prevent the overcurrent from flowing from the secondary batteries A1 and A2 via the switch circuit S31 and to prevent the switch circuit S31 from being destroyed. Thereafter, the switch circuits S11 to S1n and S21 to S2n can perform overcurrent protection by the same operation. The same applies to the setting method of the ON resistance of the switch circuit and the current value of the constant current circuit.

When the terminals T21 and T41 are short-circuited with the switch circuits S11 to S1n all turned on, a current flows from the secondary battery A1 via the switch circuit S11. At this time, the switch circuit S11 generates a voltage at both ends due to the on-resistance, and outputs a signal from the output terminal of the overcurrent detection circuit 211 to the control circuit 201 by detecting this voltage with the overcurrent detection circuit 211. The control circuit 201 receives this signal and turns off the switch circuit S11. In this way, it is possible to stop the current from flowing from the secondary battery A1 via the switch circuit S11 and to prevent the switch circuit S11 from being destroyed.

When the terminals T31 and T41 are short-circuited with all the switch circuits S11 to S1n turned on, current flows from the secondary batteries A1 and A2 through the switch circuit S11. At this time, the switch circuit S11 generates a voltage at both ends due to the on-resistance, and outputs a signal from the output terminal of the overcurrent detection circuit 211 to the control circuit 201 by detecting this voltage with the overcurrent detection circuit 211. The control circuit 201 receives this signal and turns off the switch circuit S11. Thus, it is possible to stop the current from flowing from the secondary batteries A1 and A2 via the switch circuit S11 and to prevent the switch circuit S11 from being destroyed. Hereinafter, even when short-circuited with other terminals, the current can be detected in the same manner to prevent the switch circuit S11 from being destroyed. Similarly, when the switch circuits S21 to S2n are turned on or for the cell balance devices B2 to Bn, the current when a short circuit occurs between the terminals can be detected to prevent the switch circuit from being destroyed.

Note that the circuit system for detecting the current flowing through the switch circuit is not limited to the above configuration.

Further, the cell balance device of the present embodiment has been described as taking cell balance of the secondary batteries A1 to An + 1 connected in series. An effect is obtained.

As described above, according to the battery system provided with the cell balance device of the present embodiment, it is possible to detect an overcurrent flowing through the switch circuit and to turn off the switch circuit and prevent destruction.

A1 to An + 1 Secondary batteries B1 to Bn Cell balance device C1 to Cn-1 Voltage holding device 101 Charger 102 Clock generation circuit 201 to 20n Control circuit 211 to 21n, 221 to 22n, 231 to 23n Overcurrent detection circuit 502 Constant current Circuit 503 Comparator

Claims (3)

In the cell balance device constituting the battery system for adjusting the cell balance of a plurality of capacitors connected in series,
A plurality of capacitor connection terminals to which connection points or both ends of the plurality of capacitors connected in series are connected, and
A voltage holding device connection terminal to which the voltage holding device is connected;
A plurality of first switch circuits provided between the plurality of capacitor connection terminals and the voltage holding device;
A receiving terminal for receiving a synchronization signal;
A transmission terminal for transmitting the synchronization signal;
A control circuit for controlling on / off of the plurality of first switch circuits based on the synchronization signal;
An overcurrent detection circuit for detecting an overcurrent flowing through the first switch circuit. The overcurrent detection circuit includes a second switch circuit that is on / off controlled simultaneously with the first switch circuit;
A constant current circuit for supplying a constant current to the second switch circuit;
A comparison circuit that compares the on-resistance of the first switch circuit and a voltage based on a current with the on-resistance of the second switch circuit and a voltage based on the constant current. Item 2. The cell balance device according to Item 1. A plurality of capacitors connected in series;
A plurality of voltage holding devices connected in series;
A clock generation circuit for outputting the synchronization signal;
The connection points or both ends of the plurality of capacitors connected in series are connected to the plurality of capacitor connection terminals, and the plurality of voltage holding device connection points or both ends connected in series are connected to the voltage holding device connection terminals. A battery system comprising a plurality of the cell balance devices according to claim 1.

Images