JP6390451B2 - Battery block discharge control device - Google Patents

Description

  The present invention relates to a discharge control device that discharges a plurality of battery cells constituting a battery block.

  For example, a battery used for a power source for driving electric vehicles or the like is configured by connecting a plurality of secondary battery cells in series to form a battery block, and connecting the plurality of battery blocks in series to obtain a desired power supply voltage. It is configured to be. Each battery block is connected to a monitoring circuit (for example, configured as an IC) for monitoring and controlling the terminal voltage, and the terminal voltages are controlled to be equal. The power supply for operation of these monitoring circuits is supplied by the power supply circuit generated from the power supply of the battery block to which the monitoring circuit is connected.

  However, since elements such as transistors and resistors constituting each monitoring circuit vary, even if monitoring and control of each battery block is performed in the same manner, a difference occurs in actual current consumption. Therefore, the difference in current consumption between the monitoring circuits is one of the factors that cause the terminal voltage between the battery blocks to vary.

  Patent Document 1 is one of the conventional techniques for solving such a problem. In Patent Document 1, a balance current adjustment circuit 13 is connected in parallel to the detection circuit 4 connected to each battery block 2, and the balance current adjustment circuit 13 is supplied with the balance current supplied to itself to the detection circuit 4. The load current of the battery block 2 including both currents is made uniform. The balance current is adjusted between the balance current adjustment circuits 13 so that the load current is made uniform in each battery block 2.

Japanese Patent No. 5602353

  However, in the configuration of Patent Document 1, in order to adjust the balance current, a balance current adjustment circuit 13 including a current detection resistor 12, a differential amplifier 14, an amplifier circuit 16, an output transistor 17, and the like is added separately. Yes. Therefore, many circuit elements are required, which increases the size of the configuration and increases the cost.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a discharge control device for a battery block that can be adjusted so that the terminal voltages of each battery block become equal without increasing the number of separately added circuit elements as much as possible. There is to do.

  According to the battery block discharge control apparatus of the first aspect, the switching power supply circuit generates the load power supply to be supplied to the load based on the power supply input from the battery block. The signal generating means generates a control signal for controlling the discharge state of the battery block performed by the plurality of discharging means, based on the duty of the PWM signal used by the switching power supply circuit to generate the load power supply. If comprised in this way, the discharge state of each battery block is controllable by using the PWM signal which is an internal control signal of a switching power supply circuit. Therefore, the terminal voltage of each battery block can be adjusted to be equal without adding many circuit elements.

According to the discharge control device for a battery block according to claim 4 , the switching power supply circuit includes a charge pump circuit and is based on a power supply input from a battery block formed by connecting a plurality of battery cells in series. Load power to be supplied to the load. The power discharge means is connected to the output part of the switching power supply circuit and discharges the load power supply. The discharge time control means receives the stepped-down voltage of each step-down stage part constituting the charge pump circuit, and controls the time during which the power supply discharging means discharges the load power supply according to the difference between the step-down voltages. With this configuration, even when the switching power supply circuit includes a charge pump circuit, the terminal voltage of each battery block becomes equal by discharging the load power supply according to the difference between the step-down voltages. Can be adjusted as follows.

The figure which is 1st Embodiment and shows the structure of the control system of an assembled battery Diagram showing load configuration example Diagram showing changes in load current consumption in response to changes in temperature and voltage The figure which shows the structural example of the voltage detection circuit The figure which shows the signal which controls discharge time at the time of disconnection detection The figure which shows the control sequence (operation phase) of the voltage detection circuit The figure which shows the structural example of a consumption current value control circuit The figure which shows an example in the case of adjusting discharge amount according to the terminal voltage of a battery block, and the consumption current of load The figure which is 2nd Embodiment and shows the structure of a consumption current value control circuit Operation timing chart The figure which is 3rd Embodiment and shows the structure of the control system of an assembled battery Diagram showing a configuration example of a discharge circuit Operation flowchart The figure which is 4th Embodiment and shows the structure of the control system of an assembled battery The figure which is 5th Embodiment and shows the structural example of a voltage detection circuit

(First embodiment)
As shown in FIG. 1, the assembled battery 1 is configured by connecting n battery blocks 2 (1) to 2 (n) in series, and the battery block 2 includes m battery cells 3 in series. Connected to and configured. ICs (discharge control devices) 4 (1) to 4 (n) are connected to the battery blocks 2 (1) to 2 (n), respectively. The IC 4 includes a voltage detection circuit 5, a switching power supply circuit 6, a load 7, a current consumption control circuit 8 (signal generation means), and the like. The switching power supply circuit 6 is connected to both terminals (+ B, −B) of the battery block 2, and supplies the operating power generated by stepping down the terminal voltage of the battery block 2 to the load 7.

  As shown in FIG. 2, it is assumed that the load 7 includes constant current circuits 7a and 7b, for example. In the constant current circuit 7a, the current flowing through the resistance element R1 connected between the base and emitter of the NPN transistor Tr1 is defined as current (1). In the constant current circuit 7b, the NPN transistors on the ground side are connected to both ends of the battery block 2. The current flowing through the resistance element R2 connected in series with Tr2 is defined as current (2). These currents (1) and (2) change according to the resistance values, temperature, and power supply voltage of the resistance elements R1 and R2, respectively, as shown in FIGS. 3 (a) and 3 (b). This causes a variation in the terminal voltage of the battery block 2.

  As shown in FIG. 4, the voltage detection circuit 5 is connected to both terminals of each battery cell 3 via resistance elements 11 and 12, and a capacitor 13 is connected between the resistance elements 11 and 12. Connected outside. A Zener diode 14 and a P-channel MOSFET 15 (discharge means) are connected between the resistance elements 11 and 12 inside the voltage detection circuit 5. Between the positive terminal of the uppermost battery cell 3 (1) and the negative terminal of the lowermost battery cell 3 (m), a series circuit of a resistance element 16 and an N-channel MOSFET 17 (discharge means) is provided. Is connected.

  The positive and negative terminals of each battery cell 3 are connected to a detection control circuit 18 (discharge means) inside the voltage detection circuit 5 via resistance elements 11 and 12, respectively. The detection control circuit 18 has a built-in multiplexer (not shown), and switches and inputs the terminal voltage of each battery cell 3 to detect it. At this time, as shown in FIG. 3 is discharged, and disconnection detection and leakage current detection are performed depending on whether or not the terminal voltage of the battery cell 3 is restored when the FET 15 is turned off. The FET 17 is ON / OFF controlled at both ends of the battery block 2 in order to detect the terminal voltage and disconnection in the same manner as described above. Further, the detection control circuit 18 controls the time during which the FET 15 or 17 is turned on in accordance with a discharge time signal (control signal) input from the current consumption value control circuit 8 as will be described later.

  In disconnection detection, (1) the FET 17 is turned on, (2) the FET 15 corresponding to the odd-numbered battery cell 3 is turned on / off, and the voltages of all the battery cells 3 are measured. The FET 15 corresponding to the cell 3 is turned on / off, and the voltages of all the battery cells 3 are measured. As a result, the battery cells 3 (2) to 3 (m−1) are “disconnected” if there is a change in the voltage measurement values of (2) and (3). For the battery cells 3 (1) and 3 (m), the corresponding FET 15 is individually turned on / off, and the voltage measurement becomes −VF (forward voltage of the Zener diode 14), “disconnected” (details) (For example, refer to JP2014-48087A and WO2012 / 164761).

  Refer to FIG. 1 again. The consumption current value control circuit 8 receives the duty of the PWM signal used by the switching power supply circuit 6 for switching control. Then, the consumption current value control circuit 8 determines the above-described discharge time signal according to the duty value and outputs it to the detection control circuit 18.

  As shown in FIG. 6, the voltage detection circuit 5 performs “equalization” of the battery cells 3 and the battery blocks 2, “failure detection” for detecting disconnection and leakage current, and transmission of detection results to the load 7. Each operation phase of “communication” is repeatedly executed. The above discharge time corresponds to the disconnection detection execution time.

  As shown in FIG. 7, the consumption current value control circuit 8 is configured by, for example, a DA (Duty / Analog) converter 8a (converter), an AD converter 8b (converter), and a map 8c (discharge time map). . The DA converter 8a is constituted by an integrator, for example, and generates a voltage signal corresponding to the duty of the input PWM signal. The AD converter 8b performs A / D conversion on the voltage signal, and the map 8c stores a discharge time signal set according to the A / D conversion data, and the discharge time signal according to the input data. Is output.

  The voltage detection circuit 5 not only determines the discharge time according to the input discharge time signal, but also refers to the terminal voltage of the battery block 2 at that time, for example, as shown in FIG. May be adjusted. That is, when the terminal voltage of the battery block 2 is high (than the standard value) and the current consumption of the load 7 is small, a large amount of discharge current flows, but when the current consumption of the load 7 is large, the discharge current is not excessively large. adjust. Further, when the terminal voltage of the battery block 2 is low and the current consumption of the load 7 is small, the discharge current is not so much flowed as described above, and when the current consumption of the load 7 is large, the discharge current is hardly flowed. Adjust as follows.

  As described above, according to the present embodiment, the switching power supply circuit 6 generates the load power supply to be supplied to the load 7 based on the power input from the battery block 2. The consumption current value control circuit 8 is a discharge time for controlling the discharge state of the battery block 2 performed by the FETs 15 and 17 based on the duty of the PWM signal used by the switching power supply circuit 6 to generate the load power supply. Generate a signal.

  In this case, the consumption current value control circuit 8 is configured by a DA converter 8a, an AD converter 8b, and a map 8c, and a discharge time corresponding to the digital value is read from the map 8c to generate a discharge time signal. If comprised in this way, the discharge state of each battery block 2 is controllable by using the PWM signal which is an internal control signal of the switching power supply circuit 6. Therefore, the terminal voltage of each battery block 2 can be adjusted to be equal without adding many circuit elements. Moreover, the voltage detection circuit 5 can adjust the terminal voltage of each battery block 2 with higher accuracy by adjusting the discharge time according to the terminal voltage of the battery block 2 at that time.

(Second Embodiment)
Hereinafter, the same parts as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different parts will be described. As shown in FIG. 9, the consumption current value control circuit 21 (signal generation means) of the second embodiment includes an integrator 22 (voltage signal generation means), comparators 23 (1) to 23 (n), and a logic circuit 24. It is configured.

  The integrator 22 converts the PWM signal into a voltage signal in the same manner as the DA converter 8a of the first embodiment, and outputs the voltage signal to the non-inverting input terminals of the comparators 23 (1) to 23 (n). Different reference voltages Vref1 to Vrefn are applied to the inverting input terminals of the comparators 23 (1) to 23 (n), respectively. The output terminals of the comparators 23 (1) to 23 (n) are connected to the input terminals of the logic circuit 24, respectively. Each reference voltage is set to satisfy (Vref1 <Vref2 <... <Vrefn). In addition, a timing signal is input to the logic circuit 24. This timing signal is output at a timing when the voltage detection circuit 5 starts to turn on the FET 15 to detect disconnection.

  Next, the operation of the third embodiment will be described. The comparators 23 (1) to 23 (n) compare the voltage signal input from the integrator 22 with the reference voltages Vref 1 to Vrefn to generate signals IN 1 to INn (comparison result signals), and the logic circuit 24. Output to. The logic circuit 24 determines the discharge time signal according to which of the signals IN1 to INn indicates a high level.

For example, if all the signals IN1 to INn are at a low level, the discharge time is set to (t _D + t). If only the signal IN1 is at a high level, the discharge time is set to (t _D + 2t), and all the signals to the signal INn are high. If it is level, the discharge time is set to {t _D + (n + 1) t}. Then, as shown in FIG. 10, when the timing signal is input, the logic circuit 24 outputs a discharge time signal to the voltage detection circuit 5 as a trigger.

  As described above, according to the second embodiment, the consumption current value control circuit 21 includes the integrator 22, the comparators 23 (1) to 23 (n), and the logic circuit 24. Also in this case, the same effect as the first and second embodiments can be obtained.

(Third embodiment)
As shown in FIG. 11, the IC 31 (discharge control device) of the third embodiment includes a consumption current value control circuit 32 (information transmission means, discharge time control means) and a discharge circuit 33 connected to both ends of the battery block 2. (Discharge means) and a communication circuit 34 (information transmission means). The consumption current value control circuit 32 communicates with an external microcomputer (microcomputer) 36 (control circuit) via the bus 35 by the communication circuit 34. The consumption current value control circuit 32 outputs a discharge amount control signal to the discharge circuit 33 as will be described later.

  As shown in FIG. 12, the P-channel MOSFETs 36a and 36b of the discharge circuit 33 are connected to the terminal + B side of the battery block 2 to form a current mirror circuit. A series circuit of an N-channel MOSFET 37 and a resistance element 38 is connected between the drain of the FET 36a and the terminal -B. The inverting input terminal of the operational amplifier 39 is connected to the source of the FET 37, and the output terminal is connected to the gate of the FET 37.

A discharge amount control signal (V) is input from the consumption current value control circuit 32 to the non-inverting input terminal of the operational amplifier 39. If the resistance value of the resistance element 38 is R and the mirror ratio of the current mirror circuit is 1: n, the current I flowing out from the drain of the FET 36b is (= n × V / R). The drain is connected to a terminal -B of the battery block 2 via a resistance element _RD . The consumption current value control circuit 32 replaces the map 8c in the consumption current value control circuit 8 of the first embodiment with a CPU, and executes processing by software.

  Next, the operation of the third embodiment will be described. As shown in FIG. 13, the voltage of the battery block 2 changes as the current consumed by the load 7 changes. As a result, the PWM duty of the switching power supply circuit 6 changes (S1). When the current consumption value control circuit 32 acquires the duty value via the A / D converter 8b (S2), it transmits the data to the microcomputer 36 via the communication circuit 33.

  The microcomputer 36 calculates the current consumption of the battery block 2 from the received duty value (S3). Then, it is determined whether or not the calculated consumption current varies between the ICs 31 (S4). If there is a variation (YES), the discharge adjustment amount is calculated so that the consumption current amount of each IC 31 is the same (S5), and transmitted to each IC 31. Then, the consumption current value control circuit 32 of each IC 31 outputs a discharge amount control signal to the discharge circuit 33 according to the discharge adjustment amount transmitted from the microcomputer 36, and adjusts the discharge amount (S6).

  As described above, according to the third embodiment, the PWM duty of the switching power supply circuit 6 is input to the transmission circuit 34 via the consumption current value control circuit 32 as information indicating the consumption current amount, and the information is input to the microcomputer 36. Send to. The microcomputer 36 uses the information obtained by communicating with the current consumption value control circuit 32 of each battery block 2 to individually control the discharge time control signal so that the amount of current consumed by each switching power supply circuit 6 becomes equal. Send. Then, the consumption current value control circuit 32 causes the discharge circuit 33 to discharge the battery block 2 based on the control signal. If comprised in this way, the information which shows the consumption current amount of each battery block 2 will be collected by the microcomputer 36, and it will adjust so that the terminal voltage of each battery block 2 may become equal based on the control signal transmitted from the microcomputer 36 Is done.

(Fourth embodiment)
As shown in FIG. 14, the IC 41 (discharge control device) of the fourth embodiment includes a switching power supply circuit 42 configured by a step-down charge pump circuit. The IC 41 also includes a voltage detection circuit 43 and a consumption current control circuit 44 (discharge time control means) that replace the configuration of the first embodiment, and a discharge circuit 45 (power supply discharge) is provided on the output side of the switching power supply circuit 42. Means) are arranged.

  The switching power supply circuit 42 has an n-stage configuration, and each step-down stage section 46 includes a series circuit of a switch circuit 47 and a diode 48, and a capacitor 49 connected between the cathode of the diode 48 and the terminal -B. ing. The switch circuit 47 of each step-down stage unit 46 is on / off controlled by a PWM signal supplied from the sense unit 50 (discharge time control means). Further, the output voltage of each step-down stage unit 46 is input to the sense unit 50. The discharge control by the discharge circuit 45 is performed by the consumption current control circuit 44.

  Next, the operation of the fourth embodiment will be described. The sense unit 50 outputs a PWM signal having the same duty to the switch circuit 47 of each step-down stage unit 46, so that each step-down stage unit 46 reduces the voltage at a constant rate. In that case, the voltage of the battery block 2 is calculated by referring to the amount of decrease in the output voltage of each step-down stage 46 and output to the consumption current control circuit 44. Then, the current consumption control circuit 44 discharges the power output from the switching power supply circuit 42 by the discharge circuit 45 in accordance with the magnitude of the voltage.

  As described above, according to the fourth embodiment, the switching power supply circuit 42 includes the charge pump circuit, and generates the load power supply to be supplied to the load 7 based on the power input from the battery block 2. . The discharge circuit 45 is connected to the output part of the switching power supply circuit 42 and discharges the load power supply. The sense unit 50 is input with the step-down voltage of each step-down stage unit 46 constituting the charge pump circuit, and controls the discharge time of the load power source by the discharge circuit 45 according to the difference between the step-down voltages. With this configuration, even when the switching power supply circuit 42 includes a charge pump circuit, the load power supply is discharged according to the difference between the step-down voltages, and the terminal voltages of the battery blocks 2 are equal. Can be adjusted.

(Fifth embodiment)
As shown in FIG. 15, in the voltage detection circuit 51 of the fifth embodiment, another P-channel MOSFET 52 (discharge means) is connected in parallel to the FET 16. The detection control circuit 53 adjusts the amount of discharge depending on whether one of the FETs 16 and 52 is turned on or both are turned on simultaneously. In this case, the FET 52 may be the same size as the FET 16 or a different size. In addition, for example, a resistance element may be inserted on the source side of the FET 52 to adjust the resistance value when turned on.

The present invention is not limited to the embodiments described above or shown in the drawings, and the following modifications or expansions are possible.
A bipolar transistor may be used as the discharging means.

  In the drawings, 1 is an assembled battery, 2 is a battery block, 3 is a battery cell, 4 is an IC (discharge control device), 6 is a switching power supply circuit, 7 is a load, 8 is a current consumption control circuit (signal generation means), 15 Denotes a P-channel MOSFET (discharge means), and 18 denotes a detection control circuit (discharge means).

Claims (4)

A plurality of discharging means (15, 17, 52) for discharging the battery block (2) formed by connecting a plurality of battery cells (3) in series;
A switching power supply circuit (6) for generating a power supply for a load to be supplied to the load (7) based on a power supply input from the battery block;
A PWM signal used by the switching power supply circuit to generate the load power supply is input, and a control signal for controlling a discharge state performed by the plurality of discharge means is generated based on a duty of the PWM signal. A battery block discharge control device comprising signal generation means (8, 21). The signal generating means (8)
Conversion means (8a, 8b) for converting the duty of the PWM signal into a digital value;
A discharge time map (8c) in which a discharge time corresponding to the digital value is stored;
The discharge control device for a battery block according to claim 1, wherein the control signal is generated by reading a discharge time corresponding to the digital value from the discharge time map. The signal generating means (21)
Voltage signal generating means (22) for generating a voltage signal according to the duty of the PWM signal;
A plurality of comparators (23) for comparing the voltage signals with different threshold voltages;
The battery block discharge control according to claim 1, further comprising: a logic circuit (24) that receives the comparison result signals of the plurality of comparators and generates the control signal according to the value of each comparison result signal. apparatus. A switching power supply circuit (42) configured to generate a load power supply to be supplied to a load based on a power supply input from a battery block formed by connecting a plurality of battery cells in series with a charge pump circuit;
A power discharge means (45) connected to the output of the switching power supply circuit for discharging the load power supply;
A discharge time control means (44) for receiving a step-down voltage of each step-down stage constituting the charge pump circuit and controlling a time for discharging the power supply for load by the power supply discharge means in accordance with a difference between the step-down voltages. A discharge control device for a battery block, comprising:

Images