JP2013055837A - Voltage-balance correction circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage-balance correction circuit, which corrects a voltage balance of a plurality of secondary batteries connected in series, that allows, in particular, reducing the number of circuit elements, shortening the processing time of overcurrent detection, and performing the overcurrent detection without delay.SOLUTION: A voltage-balance correction circuit for first and second batteries connected in series includes: a first switching element connected in parallel to the first battery; a second switching element connected in parallel to the second battery; an inductor that is disposed between the connection portion of the first and second batteries and the connection portion of the first and second switching elements, turns on the first switching element, charges electromagnetic energy by driving the first battery, turns on the second switching element, and charges the second battery by the electromagnetic energy; and control means that detects an overcurrent to the first and second switching elements, and then turns off the first and second switching elements when detecting the overcurrent.

Description

  The present invention relates to a voltage balance correction circuit that corrects the voltage balance of a plurality of secondary batteries connected in series.

  Nowadays, secondary batteries such as lithium ion batteries and nickel metal hydride storage batteries are widely used not only for so-called hybrid cars and electric vehicles, but also as backup power sources for forklifts and various industrial machines. Therefore, a large output is required for a secondary battery used for such an application, and a large number of batteries are connected in series. In this case, it is particularly important that the output voltages of the batteries connected in series match each other. For this reason, a voltage balance correction circuit is incorporated.

  FIG. 5 is a basic circuit of a voltage balance correction circuit for correcting the voltage balance of two secondary batteries connected in series. The batteries B1 and B2 are connected in series, one end of the inductor L is connected to the negative terminal of the battery B1 and the positive terminal of the battery B2, and the switching element S1 is disposed between the positive terminal of the battery B1 and the other end of the inductor L. The switching element S2 is disposed between the negative terminal of the battery B2 and the other end of the inductor L.

  A control signal is output to the switching elements S1 and S2 from a signal generation circuit (not shown). For example, when the output voltage of the battery B1 is higher than the output voltage of the battery B2, the switching element S1 is first turned on and the switching element S2 is turned off. The current in the direction of the arrow (solid line) is passed through the inductor L, electromagnetic energy is accumulated by the induced electromotive force generated in the inductor L, and then the switching element S1 is turned off and the switching element S2 is turned on and accumulated in the inductor L. Battery B2 is charged by electromagnetic energy. On the other hand, when the output voltage of the battery B2 is higher than the output voltage of the battery B1, contrary to the above, the switching element S2 is first turned on and the switching element S1 is turned off, and then the switching element S1 is turned on and the switching element is turned on. By turning off S2, a current in the direction of the arrow (dotted line) flows through the inductor L, and the battery B1 is charged by the electromagnetic energy accumulated in the inductor L.

  Patent Document 1 discloses a circuit for preventing an overcurrent from flowing through an inductor L in a voltage balance correction circuit. FIG. 6 shows an example of a balance correction circuit disclosed in Patent Document 1. In addition to the batteries B1 and B2, the inductor L, and the switching elements S1 and S2, a series circuit of a resistor R1 and a sub-switching element S3 in parallel with the switching element S1. Are connected, and a series circuit of a resistor R2 and a sub-switching element S4 is connected in parallel to the switching element S2, thereby constituting bypass circuits of the switching elements S1 and S2, respectively.

  Further, the comparator 20 compares the voltage at the connection between the resistor R1 and the sub switching element S3 with the reference voltage V1 in order to prevent the overcurrent from flowing through the inductor L, detects the overcurrent, and sets the gate driver D3. The detection signal is output to the signal generation circuit 10 via Similarly, the comparator 21 compares the voltage at the connection between the resistor R2 and the sub-switching element S4 with the reference voltage V2, detects an overcurrent, and sends a detection signal to the signal generation circuit 10 via the gate driver D4. Output.

  As described above, the control signals are input to the switching elements S1 and S2 from the signal generation circuit 10 via the corresponding gate drivers D1 and D2, and the voltage balance of the batteries B1 and B2 is corrected. Yes.

JP 2006-67742 A

  In the conventional voltage balance correction circuit, the sub-switching elements S3 and S4 are necessary as described above, and the number of circuit elements to be used increases. Further, the sub-switching elements S3 and S4 are driven based on the control signal output from the signal generating circuit 10, the voltage generated at the connection between the resistor R1 and the sub-switching element S3 is compared with the reference voltage V1, and the resistance The voltage generated at the connection portion between R2 and the sub switching element S4 is compared with the reference voltage V2, and overcurrent detection is performed. For this reason, overcurrent detection is delayed.

  Accordingly, an object of the present invention is to provide a voltage balance correction circuit that reduces the number of circuit elements and has a small overcurrent detection delay.

  According to the present invention, the first and second batteries connected in series and the first battery connected in parallel to the first battery and driven on and off by a first control signal are provided. Switching means, a single second switching means connected in parallel to the second battery and driven to be turned on and off by a second control signal, and a connection portion between the first and second batteries, and the second battery 1. It is disposed between the connecting portions of the first and second switching means, and turns on the first switching means and turns off the second switching means to drive the first battery to accumulate electromagnetic energy. An inductor for charging the second battery by turning on the second switching means and turning off the first switching means, an overcurrent detection means for detecting an overcurrent to the inductor, and the overcurrent Upon detection can be accomplished by providing a voltage balance correction circuit and a control means for turning off the first, second switching means. That is, when the overcurrent detection means detects an overcurrent to the inductor during the accumulation of electromagnetic energy in the inductor, the first or second switching element is turned off and the supply of the overcurrent to the inductor is stopped. Overcurrent detection is performed with a small number of switching elements.

  Further, according to the present invention, the control means turns off the first and second switching means by the overcurrent detection signal detected by the overcurrent detection means and the first and second control signals. The configuration allows overcurrent detection without delay.

  Further, the overcurrent detection means is configured to perform overcurrent detection by comparing a potential that changes by turning on the first and second switching means and a preset reference potential, thereby reducing circuit elements.

  According to the present invention, overcurrent detection of the voltage balance correction circuit can be performed without increasing the number of switching elements. Further, the overcurrent detection is performed simultaneously with the output of the control signal, and the delay of the overcurrent detection of the voltage balance correction circuit can be reduced.

It is a circuit diagram of the voltage balance correction circuit of this embodiment. It is a figure explaining the logic of a drive signal generation circuit. It is a time chart which shows the voltage change of each part of a voltage balance correction circuit. It is a circuit diagram explaining the position of each part shown in a time chart. It is a basic circuit diagram which corrects the voltage balance of two continuous secondary batteries. It is a figure which shows an example of the balance correction circuit disclosed by patent document.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram of a voltage balance correction circuit according to this embodiment. Batteries E1 and E2 represent any two batteries connected in series, and a battery (not shown) having the same configuration is connected to the positive terminal of the battery E1, and the negative terminal of the battery E2 is also connected to the negative terminal of the battery E2. A battery (not shown) having the same configuration is connected. As the batteries E1 and E2, for example, lithium ion batteries are used.

  Further, in the balance correction circuit of the present embodiment, two switching elements SW1 and SW2 are used, and one end of the inductor L is connected to the connection portion of the switching elements SW1 and SW2, and the other end of the inductor L is connected to the battery E1. Are connected to the positive terminal of the battery E2. The switching elements SW1 and SW2 and the inductor L correct the voltage balance of the batteries E1 and E2, as in the case described with reference to FIG.

  A resistor RS1 is connected between the other end of the switching element SW1 and the positive terminal of the battery E1, and a resistor RS2 is connected between the other end of the switching element SW2 and the negative terminal of the battery E2.

  A drive signal is output from the drive signal generation circuit 1 to the switching element SW1 to drive the switching element SW1. In addition, a drive signal is output from the drive signal generation circuit 2 to the switching element SW2 to drive the switching element SW2. When the switching elements SW1 and SW2 are constituted by MOSFETs, gate signals are output from the corresponding drive signal generation circuit 1 or 2 to the corresponding switching elements SW1 and SW2.

  The drive signal generation circuit 1 is configured by a gate circuit having logic described later, and outputs a drive signal to the switching element SW1 based on a cutoff signal A1 output from the comparator 3 and a control signal B1 described later. Similarly, the drive signal generation circuit 2 is also composed of a gate circuit having the same logic as described above, and outputs a drive signal to the switching element SW2 based on a cutoff signal A2 output from the comparator 4 and a control signal B2 described later.

  The comparator 3 is a circuit that detects an overcurrent flowing through the inductor L, and the voltage at the connection portion of the resistors R11 and R12 divided by the resistors R11, R12, R21, and R22 is applied to the inverting input (+). The voltage at the connection between the switching element SW1 and the resistor RS1 is applied to the non-inverting input (−). The comparator 3 uses the voltage value input to the inverting input (+) as a reference voltage, and when the voltage value input to the non-inverting input (−) exceeds the reference voltage, the comparator 3 outputs a cutoff signal A1 (“0” described later) as a drive signal Output to the generation circuit 1.

  Similarly, the comparator 4 is a circuit that detects an overcurrent flowing through the inductor L, and the voltage at the connection portion of the resistors R21 and R22 divided by the resistors R11, R12, R21, and R22 is applied to the non-inverting input (−). Is applied, and the voltage at the connection between the switching element SW2 and the resistor RS2 is applied to the inverting input (+). The comparator 4 uses the voltage input to the non-inverting input (−) as a reference voltage, and when the voltage input to the inverting input (+) exceeds the reference voltage, the comparator 4 generates a cutoff signal A2 (“0” to be described later) as the drive signal generation circuit 2. Output to.

  FIG. 2 is a diagram for explaining the circuit logic of the drive signal generating circuit 1. This is so-called AND logic, and when the cutoff signal A1 is “0”, no drive signal is output to the switching element SW1 regardless of whether the control signal B1 is “0” or “1”. On the other hand, when the cutoff signal A1 is “1”, a drive signal is output to the switching element SW1 according to the control signal B1.

  The circuit logic of the drive signal generation circuit 2 is the same. When the cutoff signal A2 is “0”, the drive signal is sent to the switching element SW2 regardless of whether the control signal B2 is “0” or “1”. Do not output. On the other hand, when the cutoff signal A2 is “1”, a drive signal is output to the switching element SW2 according to the control signal B2.

  The control signals B1 and B2 are signals supplied from a comparison circuit (not shown), the output voltage of the battery E1 is compared with the output voltage of E2, and the control signals B1 and B2 according to the comparison result correspond from the comparison circuit. Is output to the drive signal generation circuit 1 or 2.

Next, the circuit operation of the overcurrent protection of this example will be described.
FIG. 3 is a time chart showing the voltage change of each part of the voltage balance correction circuit. FIG. 4 shows the measurement position of the circuit shown in the time chart. Note that “n11” shown in both figures indicates the potential at the connection between the resistors R11 and R12, and “n21” indicates the potential at the connection between the resistors R21 and R22. “N12” indicates the potential at the connection between the switching element SW1 and the resistor RS1, and “n22” indicates the potential at the connection between the switching element SW2 and the resistor RS2. “N13” indicates the output of the comparator 3, “n23” indicates the output of the comparator 4, “n14” indicates a control signal input to the drive signal generation circuit 1, and “n24” indicates the drive signal generation circuit 2. Indicates the control signal to be input. Further, “n15” indicates the output of the drive signal generation circuit 1, and “n25” indicates the output of the drive signal generation circuit 2.

  3 is an example when the output voltage of the battery E1 is higher than the output voltage of the battery E2. In this case, the control signal “n14” is output first, and then the control signal “n24” is output. Is output.

First, at the timing of t ₀ shown in FIG. 3, the control signal "n14" and "n24" has not been outputted, the switching elements SW1 and SW2 are off. The potential “n11” at the connection point between the resistors R11 and R12 and the potential “n21” at the connection point between the resistors R21 and R22 are the sum of the output voltages of the battery E1 and the battery E2 at the resistors R11, R12, R21, and R22. The divided voltage is set, “n11” is set to the voltage (reference voltage) at the connection between the resistors R11 and R12, and “n21” is set to the voltage (reference voltage) at the connection between the resistors R21 and R22. Yes. Therefore, at this time, the voltage “n11” is applied to the inverting input (+) of the comparator 3, and the voltage “n21” is applied to the non-inverting input (−) of the comparator 4.

  Here, the voltage of the positive terminal of the battery E1 is applied to the non-inverting input (−) of the comparator 3 via the resistor RS1, and the output “n13” of the comparator 3 is “1” (H level). Further, the voltage at the negative terminal of the battery E2 is applied to the inverting input (+) of the comparator 4 via the resistor RS2, and the output “n23” of the comparator 3 is also “1”.

After that, when the control signal “n14” is output to the drive signal generation circuit 1 at the timing t ₁ shown in FIG. 3, the drive signal generation circuit 1 outputs the output signal “n15” according to the logic shown in FIG. To do. That is, the output “n13” from the comparator 3 is “1” (the cutoff signal A1 is “1”) as described above, and the control signal “n14” is also “1” (the control signal B1 is also “1”). Therefore, the output signal “n15” of the drive signal generating circuit 1 becomes “1”, and the switching element SW1 is turned on.

When the switching element SW1 is turned on, a current flows through the inductor L via the resistor RS1, and electromagnetic energy is accumulated in the inductor L. Thereafter, the potential of the "n12" end of the resistor RS1 is gradually decreases, for example, at timing t ₂ shown in FIG. 3, becomes lower than the reference voltage of the "n11". The reference voltage “n11” is set corresponding to the upper limit of the accumulation of electromagnetic energy in the inductor L, and stops the current supply to the inductor L beyond this. That is, when the potential “n12” at one end of the resistor RS1 becomes lower than the reference voltage “n11”, the potential on the inverting input (+) side of the comparator 3 becomes higher than the potential on the non-inverting input (−) side. The output “n13” changes from “1” to “0” (L level).

  For this reason, the output “n15” of the drive signal generating circuit 1 becomes “0” according to the logic shown in FIG. 2, and the switching element SW1 is turned off. Therefore, thereafter, no overcurrent is supplied to the inductor L, and accumulation of excessive electromagnetic energy in the inductor L is prevented. At this time, the output “n15” from the drive signal generation circuit 1 is determined by directly using the output of the control signal “n14”, and is determined through another circuit (for example, the control signal is a circuit such as a comparator). Therefore, the supply of overcurrent to the inductor L can be stopped immediately.

Next, when the control signal "n24" at timing t ₃ when 3 is output to the drive signal generating circuit 2, a drive signal generation circuit 2 according to the logic shown in FIG. 2, the output "n25""1" As a driving signal is supplied to the switching element SW2. That is, at this time, the output “n23” from the comparator 4 is “1” as described above, and the control signal “n24” is also “1”, so that the drive signal generation circuit 2 drives according to the logic shown in FIG. A signal is output to the switching element SW2.

Therefore, the switching element SW2 is immediately turned on to form a closed circuit of the switching element SW2, the resistor RS2, the battery E2, and the inductor L, and the battery E2 is charged by the electromagnetic energy accumulated in the inductor L. This potential "n22" end of the resistor RS2 by charging increased to gradually, for example, at timing t ₄ when 3, becomes higher than the reference voltage of the "n21". This reference voltage “n21” corresponds to the above-described overcurrent, and corresponds to the supply end time of electromagnetic energy from the inductor L to the battery E2, and prevents unnecessary discharge by the battery E2 thereafter.

  Therefore, when the potential “n22” at one end of the resistor RS2 becomes higher than the reference voltage “n21”, the potential on the inverting input (+) side of the comparator 4 becomes higher than the potential on the non-inverting input (−) side. The output “n23” changes from “1” to “0”. For this reason, the output “n25” of the drive signal generation circuit 2 becomes “0” according to the logic shown in FIG. 2, and the switching element SW2 is turned off. Therefore, the charging process for the battery E2 is stopped thereafter. At this time, the output signal “n25” from the drive signal generation circuit 2 is determined by directly using the output of the control signal “n24”, and other circuit (for example, the control signal is a circuit such as a comparator). Since it is not determined, the closed circuit can be opened immediately.

Thereafter, the output control signal "n14" at the timing t ₅ shown in FIG. 3 again, in the same manner as described above, according to the logic shown in FIG. 2, the drive signal output "n15" is "1" and the generating circuit 1, the switching element SW1 is turned on, and electromagnetic energy is accumulated in the inductor L via the resistor RS1. Thereafter, the storage of the electromagnetic energy in the inductor L is stopped at the timing of t ₆ , and the battery E 2 is installed using the electromagnetic energy stored in the inductor L by the control signal “n 24” output at the timing of t _7. Charge.

  Thereafter, the above process is repeated, the battery E2 is charged by the battery E1, and the above process is repeated until the output voltage of the battery E1 matches the output voltage of the battery E2. During this time, the accumulation of electromagnetic energy in the inductor L is controlled by the functions of the comparators 3 and 4 so that no overcurrent is generated, and the voltage balance correction process for the batteries E1 and E2 is performed.

  Further, according to the present embodiment, the output “n15” from the drive signal generation circuit 1 is determined by directly using the output of the control signal “n14”, and is not determined via any other circuit. The overcurrent supply can be stopped immediately.

  The above embodiment is an example in the case where the output voltage of the battery E1 is higher than the output voltage of the battery E2, and the control signal “n14” is output first, and then the control signal “n24” is output. As described above, when the output voltage of the battery E1 is lower than the output voltage of the battery E2, the control signal “n24” is output first, and then the control signal “n24” is output.

  In the description of the above embodiment, overcurrent detection is performed in connection with the voltage balance correction processing of the batteries E1 and E2 connected in series. However, the batteries E1 and E2 are connected to a number of batteries in series. Any two batteries are shown, and the voltage balance correction of the other two consecutive batteries can be similarly performed.

  Furthermore, in the description of the above embodiment, the example of the lithium ion battery has been described as the batteries E1 and E2, but a nickel hydride storage battery, a nickel cadmium storage battery, or the like may be used.

1,... Driving signal generation circuit 3, 4... Comparator E 1, E 2 .. Battery R 11, R 12, R 21, R 22... Resistance RS 1, RS 2.

Claims (3)

First and second batteries connected in series;
A single first switching means connected in parallel to the first battery and driven to be turned on and off by a first control signal;
A single second switching means connected in parallel to the second battery and driven on and off by a second control signal;
It is arranged between the connection part of the first and second batteries and the connection part of the first and second switching means, and turns on the first switching means and turns off the second switching means. An inductor that drives the first battery to store electromagnetic energy and charges the second battery by turning on the second switching means and turning off the first switching means;
Overcurrent detection means for detecting an overcurrent to the inductor;
Control means for turning off the first and second switching means when detecting the overcurrent;
A voltage balance correction circuit comprising:   2. The control unit according to claim 1, wherein the control unit turns off the first and second switching units based on an overcurrent detection signal detected by the overcurrent detection unit and the first and second control signals. The voltage balance correction circuit described.   The overcurrent detection means performs overcurrent detection by comparing a potential that changes by turning on the first and second switching means with a preset reference potential, or 2. The voltage balance correction circuit according to 2.