JP2022067764A - Voltage detection device - Google Patents

Abstract

To provide a voltage detection device that individually detects a wiring resistance between a battery and a voltage detection circuit.SOLUTION: A voltage detection device D comprises: a discharge circuit including discharge resistors Z0 to Z3 and electronic switches G1 to G3, and is connected in parallel to batteries c1 to c3; voltage detection circuits A1 to A3 for detecting the voltage of each battery; and a control unit 2 that controls the electronic switches. The control unit acquires a wiring resistance value between each voltage detection circuit and each battery on the basis of a first detection voltage detected by the voltage detection circuit when the electronic switch is set in an ON state and a second detection voltage detected by the voltage detection circuit when the electronic switch is set in an OFF state.SELECTED DRAWING: Figure 1

Description

The present invention relates to a voltage detector.

The following Patent Document 1 discloses a voltage detection device including a discharge circuit and a voltage detection unit. In this voltage detection device, the discharge circuit is composed of a bypass resistor arranged in parallel with each battery cell of the battery module and a switching element that allows the bypass resistor to discharge each battery cell, and the voltage detection unit is composed of a voltage detection unit. The discharge voltage of each battery cell is determined by detecting the voltage across the bypass resistor and correcting the voltage across the circuit using the voltage drop coefficient indicating the voltage drop characteristic of the voltage across the circuit.

Japanese Unexamined Patent Publication No. 2016-1806553

By the way, the voltage drop coefficient takes into consideration the voltage drop caused by the wiring resistance between each battery cell of the battery module and the voltage detection unit (voltage detection circuit). In the above background technique, the discharge voltage of each battery cell is determined by using such a voltage drop coefficient as a known constant value.

However, the above-mentioned wiring resistance actually has a different value depending on the individual difference of the harness (connection line) connecting each battery cell and the voltage detection circuit. That is, in the background technique described above, since the voltage drop coefficient, that is, the wiring resistance is set to a known constant value, the discharge voltage of each battery cell cannot be accurately determined. Therefore, with the above background technique, it is not possible to realize an accurate cell balance of each battery cell.

The present invention has been made in view of the above circumstances, and an object of the present invention is to individually detect the wiring resistance between the battery and the voltage detection circuit.

In order to achieve the above object, in the present invention, as a first solution relating to the voltage detection device, a discharge resistor and an electronic switch are provided, and a discharge circuit connected in parallel to the battery and the voltage of the battery are detected. In a voltage detection device including a voltage detection circuit for controlling the electronic switch and a control unit for controlling the electronic switch, the control unit is the first detection detected by the voltage detection circuit when the electronic switch is set to the ON state. A means of acquiring a wiring resistance value between the voltage detection circuit and the battery based on the voltage and the second detection voltage detected by the voltage detection circuit when the electronic switch is set to the OFF state. adopt.

In the present invention, as a second solution according to the voltage detection device, in the first solution, the battery is an assembled battery in which a plurality of battery cells are connected in series, and the discharge circuit is the battery cell. The control unit is provided for each, and the control unit corresponds to the electronic switch of the discharge circuit corresponding to the even cell having the even order of connection and the odd cell having the odd order of connection among the plurality of battery cells. By alternately setting the electronic switches of the discharge circuit to the ON state or the OFF state, the means of acquiring the wiring resistance value between the voltage detection circuit and the plurality of battery cells is adopted. ..

In the present invention, as a third solution according to the voltage detection device, in the second solution, the control unit excludes the voltage drop due to the wiring resistance value based on the wiring resistance value. The means of acquiring the voltage or a plurality of actual cell voltages is adopted.

In the present invention, as a fourth solution according to the voltage detection device, in the third solution, the control unit determines a correction coefficient according to the wiring resistance value, and the actual cell is based on the correction coefficient. Adopt a means of correcting the voltage.

In the present invention, as a fifth solution according to the voltage detection device, in the third or fourth solution, the control unit executes cell balance control of a plurality of the battery cells based on the actual cell voltage. Adopt the means of doing.

In the present invention, as a sixth solution according to the voltage detection device, in any one of the first to fifth solutions, the control unit starts the first detection voltage and the second detection voltage at least immediately after the activation. The means of acquiring the voltage is adopted.

According to the present invention, it is possible to individually detect the wiring resistance between the battery and the voltage detection circuit.

It is a circuit diagram which shows the circuit structure of the voltage detection apparatus D which concerns on one Embodiment of this invention. It is a circuit diagram which shows the operation of the voltage detection apparatus D which concerns on one Embodiment of this invention. It is a flowchart which shows the operation of the voltage detection apparatus D which concerns on one Embodiment of this invention. It is a 2nd circuit diagram which shows the circuit structure of the voltage detection apparatus D which concerns on one Embodiment of this invention. It is a waveform diagram (a) and a characteristic diagram (b) which show the correction method of the detection voltage in one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the voltage detection device D according to the present embodiment targets the assembled battery B as a detection target. The voltage detection device D is mounted on an electric vehicle using a motor as a traveling power source, such as an electric vehicle or a hybrid vehicle, together with the assembled battery B, and detects the voltage of the assembled battery B.

As shown in the figure, such a voltage detection device D includes the 0th to 3rd connection lines H0 to H3, the 0th to 3rd CR filters F0 to F3, the 0th to 3rd discharge resistors Z0 to Z4, and the voltage detection IC1. It is equipped with. Further, among these components, the voltage detection IC1 includes the 0th to 3rd input terminals IN0 to IN3, the 0th to 3rd control terminals CT0 to CT3, the 1st to 3rd voltage detection circuits A1 to A3, and the first. It includes at least the third switches G1 to G3 and the control unit 2.

First, the assembled battery B will be described. In this assembled battery B, a plurality of battery cells, that is, the first to third battery cells c1 to c3 are connected in series, and the first to third battery cells c1 to c3 are connected in series. It is a secondary battery that supplies DC power of the output voltage (battery voltage), which is the sum of the electromotive voltage, to an external load. Such an assembled battery B is, for example, a lithium ion battery.

Note that FIG. 1 shows, for convenience, the configuration of the assembled battery B including the first to third battery cells c1 to c3. That is, the number of battery cells constituting the assembled battery B is not limited to three. Further, the first to third voltage detection circuits A1 to A3 and the first to third switches G1 to G3 constituting the voltage detection IC1 are provided corresponding to the battery cells, and thus the first to third voltage detection circuits are provided. The number of A1 to A3 and the first to third switches G1 to G3 changes according to the number of battery cells.

The first to third battery cells c1 to c3 have a predetermined electromotive voltage (cell voltage) and are connected in series with each other. Of these first to third battery cells c1 to c3, the first and third battery cells c1 and c3 are odd-numbered cells having an odd-numbered connection order. On the other hand, the second battery cell c2 is an even-numbered cell having an even-numbered connection order.

Further, each of the first to third battery cells c1 to c3 has a predetermined internal resistance as shown in the figure. As shown in the figure, this internal resistance exists in each of the electrodes of the first to third battery cells c1 to c3, that is, in the positive electrode and the negative electrode, and can change depending on the usage state of the assembled battery B. be.

That is, the negative electrode of the first battery cell c1 has an internal resistance r1n, and the positive electrode of the first battery cell c1 has an internal resistance r1p. Further, the negative electrode of the second battery cell c2 has an internal resistance r2n, and the positive electrode of the second battery cell c2 has an internal resistance r2p. Further, the negative electrode of the third battery cell c3 has an internal resistance r3n, and the positive electrode of the third battery cell c3 has an internal resistance r3p.

The 0th to 3rd connection lines H0 to H3 are provided corresponding to the electrodes of the 1st to 3rd battery cells c1 to c3, and are electric wires that electrically connect the voltage detection device D and the assembled battery B. be. Of these 0th to 3rd connection lines H0 to H3, one end of the 0th connection line H0 is connected to the negative electrode of the first battery cell c1, and the other end is the input end of the 0th CR filter F0 of the voltage detection device D. It is an electric wire connected to. The 0th connection line H0 has a 0th wiring resistance value R0 as a total value of its own internal resistance and contact resistance at each end.

One end of the first connection line H1 is connected to the positive electrode of the first battery cell c1, that is, the negative electrode of the second battery cell c2, and the other end is connected to the input end of the first CR filter F1 of the voltage detection device D. Is. The first connection line H1 has a first wiring resistance value R1 as a total value of its own internal resistance and contact resistance at each end.

One end of the second connection line H2 is connected to the positive electrode of the second battery cell c2, that is, the negative electrode of the third battery cell c3, and the other end is the input end of the second CR filter F2 of the voltage detection device D according to the present embodiment. It is an electric wire connected to. The second connection line H2 has a second wiring resistance value R2 as a total value of its own internal resistance and contact resistance at each end.

The third connection line H3 is a wire having one end connected to the positive electrode of the third battery cell c3 and the other end connected to the input end of the third CR filter F3 of the voltage detection device D. The third connection line H3 has a third wiring resistance value R3 as a total value of its own internal resistance and contact resistance at each end.

The 0th to 3rd CR filters F0 to F3 are low-pass filters composed of a resistor and a capacitor as shown in the figure. Of these 0th to 3rd CR filters F0 to F3, the 0th CR filter F0 has an input end connected to the other end of the 0th connection line H0 and an output end connected to the input terminal IN0 of the voltage detection IC1. Further, the input end of the 0th CR filter F0 is connected (grounded) to GND, which is a reference potential, as shown in the figure.

Further, the input end of the first CR filter F1 is connected to the other end of the first connection line H1, and the output end is connected to the input terminal IN1 of the voltage detection IC1. The input end of the second CR filter F2 is connected to the other end of the second connection line H2, and the output end is connected to the input terminal IN2 of the voltage detection IC1. Further, the input end of the third CR filter F3 is connected to the other end of the third connection line H3, and the output end is connected to the input terminal IN3 of the voltage detection IC1.

In the 0th to 3rd CR filters F0 to F3, one end of the resistor is connected to the electrode of each battery cell, and the other end is connected to one end of the capacitor and each input terminal in the voltage detection IC1. Further, in the 0th to 3rd CR filters F0 to F3, one end of the capacitor is connected to the other end of the resistor and each input terminal in the voltage detection IC 1, and the other end is grounded.

Such 0th to 3rd CR filters F0 to F3 are low-pass filters that remove noise superimposed on the voltage input to each input terminal of the voltage detection IC1 from each of the first to third battery cells c1 to c3. be. As described above, the voltage detection device D and the assembled battery B according to the present embodiment are connected by the 0th to 3rd connection lines H0 to H3, and the 0th to 3rd connection lines H0 to H3 are connected from the outside. Noise may come flying. The four 0th to 3rd CR filters F0 to F3 suppress such noise from flowing into the voltage detection IC1.

The 0th to 3rd discharge resistors Z0 to Z4 are all resistors having the same resistance value Rdis. Of these 0th to 3rd discharge resistors Z0 to Z4, one end of the 0th discharge resistor Z0 is connected to the other end of the 0th connection line H0 and the input end of the 0th CR filter F0, and the other end is voltage detection. It is connected to the control terminal CT0 of IC1. One end of the first discharge resistor Z1 is connected to the other end of the first connection line H1 and the input end of the first CR filter F1, and the other end is connected to the control terminal CT0 of the voltage detection IC1.

One end of the second discharge resistor Z2 is connected to the other end of the second connection line H2 and the input end of the second CR filter F2, and the other end is connected to the control terminal CT0 of the voltage detection IC1. One end of the third discharge resistor Z3 is connected to the other end of the third connection line H3 and the input end of the third CR filter F3, and the other end is connected to the control terminal CT0 of the voltage detection IC1.

The voltage detection IC 1 is an integrated circuit having at least a function of detecting the cell voltage of each of the first to third battery cells c1 to c3 and forcibly discharging the first to third battery cells c1 to c3. Although the operation of this voltage detection IC 1 is not shown, the operation is controlled by an external control device, and the transmission of each cell voltage to the control device and the first first based on the voltage transmission command input from the control device. -Forced discharge of the third battery cells c1 to c3.

Of the 0th to 3rd input terminals IN0 to IN3 in such a voltage detection IC1, the 0th input terminal IN0 is connected to the output end of the 0th CR filter F0 and the first input end of the first voltage detection circuit A1. There is. The first input terminal IN1 is connected to the output end of the first CR filter F1, the second input end of the first voltage detection circuit A1, and the first input end of the second voltage detection circuit A2.

The second input terminal IN2 is connected to the output end of the second CR filter F2, the second input end of the second voltage detection circuit A2, and the first input end of the third voltage detection circuit A3. The third input terminal IN3 is connected to the output end of the third CR filter F3 and the second input end of the third voltage detection circuit A3.

Of the 0th to 3rd control terminals CT0 to CT3, the 0th control terminal CT0 is connected to the other end of the 0th discharge resistor Z0 and one end of the first switch G1. The first control terminal CT1 is connected to the other end of the first discharge resistor Z1, the other end of the first switch G1, and one end of the second electronic switch G2. The second control terminal CT2 is connected to the other end of the second discharge resistor Z2, the other end of the second electronic switch G2, and one end of the third electronic switch G3. The third control terminal CT3 is connected to the other end of the third discharge resistor Z3 and the other end of the third electronic switch G3.

Of the first to third voltage detection circuits A1 to A3, in the first voltage detection circuit A1, the first input end is connected to the 0th input terminal IN0 and the second input end is connected to the first input terminal IN1. It is a voltage amplification circuit. The first voltage detection circuit A1 outputs a first detection voltage V1 indicating a voltage between the terminals of the voltage V0 of the 0th input terminal IN0 and the voltage V1 of the first input terminal IN1.

The second voltage detection circuit A2 is a voltage amplification circuit in which the first input end is connected to the first input terminal IN1 and the second input end is connected to the second input terminal IN2. The second voltage detection circuit A2 outputs a second detection voltage V2 indicating a voltage between the terminals of the voltage V1 of the first input terminal IN1 and the voltage V2 of the second input terminal IN2.

The third voltage detection circuit A3 is a voltage amplification circuit in which the first input end is connected to the second input terminal IN2 and the second input end is connected to the third input terminal IN3. The third voltage detection circuit A3 outputs a third detection voltage V3 indicating a voltage between the terminals of the voltage V2 of the second input terminal IN2 and the voltage V3 of the third input terminal IN3.

The first to third electronic switches G1 to G3 are electronic switches that are turned ON / OFF by being controlled by the control unit 2. Of these first to third electronic switches G1 to G3, one end of the first electronic switch G1 is connected to the 0th control terminal CT0, and the other end is connected to the first control terminal CT1. When the first electronic switch G1 is turned on, the other end of the 0th discharge resistor Z0 and the other end of the first discharge resistor Z1 are connected, thereby forcibly discharging the first battery cell c1.

One end of the second electronic switch G2 is connected to the first control terminal CT1, and the other end is connected to the second control terminal CT2. When the second electronic switch G2 is turned on, the other end of the first discharge resistor Z1 and the other end of the second discharge resistor Z2 are connected, thereby forcibly discharging the second battery cell c2.

One end of the third electronic switch G3 is connected to the second control terminal CT2, and the other end is connected to the third control terminal CT3. When the third electronic switch G3 is turned on, the other end of the second discharge resistor Z2 and the other end of the third discharge resistor Z3 are connected, thereby forcibly discharging the third battery cell c3.

Here, the 0th and 1st discharge resistors Z0 and Z1 and the 1st electronic switch G1 are series circuits connected in parallel to the 1st battery cell c1, and the discharge circuit (1st discharge circuit) of the present invention can be used. It is composed. Further, the first and second discharge resistors Z1 and Z2 and the second electronic switch G2 are a series circuit connected in parallel to the second battery cell c2, and constitute the discharge circuit (second discharge circuit) of the present invention. are doing. Further, the second and third discharge resistors Z2 and Z3 and the third electronic switch G3 are a series circuit connected in parallel to the third battery cell c3, and constitute the discharge circuit (third discharge circuit) of the present invention. are doing.

Further, although not shown, current detection circuits for detecting each energizing current are connected in series to the first to third electronic switches G1 to G3. That is, the first current detection circuit is connected in series to the first electronic switch G1, the second current detection circuit is connected in series to the second electronic switch G2, and the third current detection circuit is connected to the third electronic switch G3. It is connected in series.

The energizing current in the first electronic switch G1 is the first discharge current I1 flowing through the first discharge resistor Z1 when the first electronic switch G1 is in the ON state. The energizing current in the second electronic switch G2 is the second discharge current I2 flowing through the second discharge resistor Z2 when the second electronic switch G2 is in the ON state. The energizing current in the third electronic switch G3 is the third discharge current I3 that flows through the third discharge resistor Z3 when the third electronic switch G3 is in the ON state.

The control unit 2 controls such first to third electronic switches G1 to G3, and calculates the first to third actual cell voltages V1r to V3r of the first to third battery cells c1 to c3. The control unit 2 has first to third detection voltages V1on to V3on and first to third electrons of the first to third voltage detection circuits A1 to A3 when the first to third electronic switches G1 to G3 are in the ON state. The first to third actual cell voltages V1r to V3r are calculated based on the first to third detection voltages V1off to V3off of the first to third voltage detection circuits A1 to A3 when the switches G1 to G3 are in the OFF state.

The procedure for calculating the first to third actual cell voltages V1r to V3r in the control unit 2 will be described in detail in the operation description of the voltage detection device D described later. Although the details will be described later, in the voltage detection device D according to the present embodiment, the control unit 2 relates to the first to third battery cells c1 to c3 by calculating the first to third actual cell voltages V1r to V3r. Achieves more accurate cell balance control.

Next, the operation of the voltage detection device D according to the present embodiment will be described in detail with reference to FIGS. 2 to 5.

In this voltage detection device D, the control unit 2 operates according to the flowchart shown in FIG. 2 to acquire the first to third real cell voltages V1r to V3r, and these first to third real cell voltages V1r to V3r. The cell balance control of the first to third battery cells c1 to c3 is executed based on the above. That is, when the control unit 2 is started from the operation stop state, all the first to third electronic switches G1 to G3 are set to the OFF state, and the first to third detection voltages V1off to V3off at this time are set to the first to third. 3 Obtained from the voltage detection circuits A1 to A3 (step S1).

Then, the control unit 2 has a second electronic switch G2 (even switch) corresponding to the second battery cell c2 which is an even cell among the first to third battery cells c1 to c3, and the first and first odd cells. By alternately setting the first and third electronic switches G1 and G3 (odd-numbered switches) corresponding to the three battery cells c1 and c3 to the ON state or the OFF state, the 0th to 3rd connection lines H0 to H3 are related. The 0th to 3rd wiring resistance values R0 to R3 are acquired as follows.

That is, the control unit 2 sets the second electronic switch G2 (even number switch) to the ON state, and sets the first and third electronic switches G1 and G3 (odd number switch) to the OFF state. In this state, as shown in FIG. 3, the second discharge current I2 flows through the second closed circuit connecting the second battery cell c2 and the second electronic switch G2. In this state, the control unit 2 acquires the second detection voltage V2on and the first and third detection voltages V1off and V30ff from the first to third voltage detection circuits A1 to A3 (step S2).

Further, the control unit 2 sets the first and third electronic switches G1 and G3 (odd-numbered switches) corresponding to the first and third battery cells c1 and c3, which are odd-numbered cells, to the ON state, and sets the even-numbered cells to the ON state. The second electronic switch G2 (even switch) corresponding to a certain second battery cell c2 is set to the OFF state.

In this state, although not shown, the first discharge current I1 flows through the first closed circuit connecting the first battery cell c1 and the first electronic switch G1, and the third discharge current I3 is the third battery cell c3 and the third electron. It flows through the third closed circuit connecting the switch G3. The control unit 2 acquires the first and third detection voltages V1on and V3on and the second detection voltage V2off in this state from the first to third voltage detection circuits A1 to A3 (step S3).

Here, the control unit 2 performs the processes of steps S1 to S3 at least immediately after the activation. That is, it is difficult to perform the processes of steps S1 to S3 while the electric vehicle is running because it is necessary to operate the first to third electronic switches G1 to G3. Therefore, the control unit 2 performs the acquisition processing of the first to third detection voltages V1on, V2on, V3on, V1off, V2off, and V3off in steps S1 to S3 immediately after the activation, and the subsequent processing of steps S4 to S7 is appropriate. conduct.

Subsequently, the control unit 2 acquires the 0th to 3rd wiring resistance values R0 to R3 (step S4). That is, the control unit 2 has the first to third detection voltages V1on, V2on, V3on, V1off, V2off, V3off obtained by the above-mentioned steps S1 to S3 and the equations (1) to (11) described below. Based on this, the 0th to 3rd wiring resistance values R0 to R3 are acquired.

When the second electronic switch G2 (even number switch) is set to the ON state and the first and third electronic switches G1 and G3 (odd number switch) are set to the OFF state as in step S2, the second battery cell c2 and the second battery cell c2 and the second. The second discharge current I2 indicated by the broken line arrow flows through the second closed circuit connecting the electronic switch G2. That is, in this state, the following two equations (1) and (2) are established for the second closed circuit.
V2off = I2 ・ (R1 + R2) + V2on (1)
I2 = V2off / (R1 + R2 + 2Rdis) (2)

Further, regarding the first and second wiring resistance values R1 and R2 constituting the second closed circuit through which the second discharge current I2 flows, the following equation (3) is based on the above two equations (1) and (2). Is obtained.
(R1 + R2) = -2Rdis ・ (V2on-V2off) / V2on (3)

On the other hand, in the state of step S2, the third detection voltage V3off detects the voltage increase when the second discharge current I2 flows through the wiring resistance R2 in the cell voltage of the third battery cell c3. Therefore, the following relational expressions (4) and (5) using the second discharge current I2 are established. Then, based on these two equations (4) and (5), the following equation (6) regarding the second wiring resistance value R2 is obtained.

V3off = V3on-I2 ・ R2 (4)
I2 ・ R2 = V3off-V3on (5)
R2 = (V3off-V3on) / I2 (6)

Then, the control unit 2 calculates the second wiring resistance value R2 in the second connection line H2 based on the above equation (6). That is, the control unit 2 substitutes the third detection voltage V3off obtained in step S1 and the third detection voltage V3on obtained in step S2 into the equation (6), and the third current detection circuit obtains the third detection voltage V3on. 2 By substituting the discharge current I2 into the equation (6), the second wiring resistance value R2 is obtained.

Further, in the state of step S2, the first detection voltage V1off detects the voltage increase when the second discharge current I2 flows through the wiring resistance R1 in the cell voltage of the first battery cell c1. The following relational expressions (7) and (8) are established for this first closed circuit. Then, based on these two equations (7) and (8), the following equation (9) regarding the first wiring resistance value R1 is obtained.

V1off = V1on-I2 ・ R1 (7)
I2 ・ R1 = V1off-V1on (8)
R1 = (V1off-V1on) / I2 (9)

Then, the control unit 2 calculates the first wiring resistance value R1 in the first connection line H1 based on the above equation (9). That is, the control unit 2 substitutes the first detection voltage V1off obtained in step S1 and the first detection voltage V1on obtained in step S2 into the equation (9), and the second current detection circuit obtains the first detection voltage V1on. 2 By substituting the discharge current I2 into the equation (9), the first wiring resistance value R1 is obtained.

Further, the following equation (10) is established for the 0th and 1st wiring resistance values R0 and R1. Further, the following equation (11) is established for the second and third wiring resistance values R2 and R3 constituting the third closed circuit.
(R0 + R1) = -2Rdis · (V1on-V1off) / V1on (10)
(R2 + R3) = -2Rdis ・ (V3on-V3off) / V3on (11)

The control unit 2 calculates the 0th wiring resistance value R0 based on the above equations (9) and (10). Further, the control unit 2 calculates the third wiring resistance value R3 based on the above equations (6) and (11). That is, the control unit 2 acquires the wiring resistance values R0 to R3 for all the 0th to 3rd connection lines H0 to H3 by the processing of steps S1 to S3 (step S4). In the present embodiment, the wiring resistance values R0 to R3 are obtained in the order of R2 → R1 → R0 → R3, but any wiring resistance value may be used as a reference regardless of the order.

In the present embodiment, since the assembled battery B has only three cells, the wiring resistance values R0 to R3 for all the 0th to 3rd connection lines H0 to H3 can be acquired in steps S1 and S2. A battery pack containing many cells, for example, when there are five cells as shown in FIG. 4, the even-numbered switch is ON, and when the odd-numbered switch is OFF, the first, third, and fifth electronic switches G1, G3, and G5 are used. When the (odd number switch) is set to the OFF state, the wiring resistance values R2 to R5 can be obtained by using the above method even in the fourth closed circuit connecting the fourth battery cell c4 and the fourth electronic switch G4.

Further, when the first, third, and fifth electronic switches G1, G3, and G5 (odd-numbered switches) are set to the ON state and the second and fourth electronic switches are set to the OFF state (step S3), the third battery cell. Also in the third closed circuit (not shown) connecting c3 and the third electronic switch G3, the wiring resistance values R1 to R4 can be obtained by using the above method.

It should be noted that any one of the duplicated wiring resistance values acquired by a plurality of closed circuits may be used as a representative in the next and subsequent steps, but the accuracy is improved by averaging the multiple acquired wiring resistance values. Can be made to. For example, the wiring resistance values R2 acquired in each of the second closed circuit, the third closed circuit, and the fourth closed circuit may be averaged and used in the next and subsequent steps.

Then, when the control unit 2 acquires the 0th to 3rd wiring resistance values R0 to R3 in this way, the 0th to 3rd wiring resistance values R0 are based on the following equations (12) to (14). The true detection voltage of the first to third battery cells c1 to c3 excluding the voltage drop caused by R3, that is, the first to third real cell voltages V1r to V3r are acquired (step S5).

V1r = V1on + (R0 + R1 + 2Rdis) · I1 (12)
V2r = V2on + (R1 + R2 + 2Rdis) · I2 (13)
V3r = V3on + (R2 + R3 + 2Rdis) ・ I3 (14)

Here, the control unit 2 sets the first to third electronic switches G1 to G3 to the setting state of step S2, and then sets the setting state of step S3, that is, the setting state of step S2 to the opposite state. The first to third detection voltages V1on, V2on, V3on, V1off, V2off, and V3off are acquired, and the input ends of two CR filters are connected to each of the first to third closed circuits.

That is, the input ends of the 0th CR filter F0 and the 1st CR filter F1 are connected to the first closed circuit, respectively. The input ends of the first CR filter F1 and the second CR filter F2 are connected to the second closed circuit, respectively. Further, the input ends of the second CR filter F2 and the third CR filter F3 are connected to the third closed circuit, respectively.

Since the 0th to 3rd CR filters F0 to F3 are low-pass filters and each has a time constant, the terminal voltages of the input terminals IN0 to IN3 are as shown in FIG. 5A. After the states of the first to third electronic switches G1 to G3 are set to the ON state or the OFF state, the state changes with the passage of time.

That is, the terminal voltages of the input terminals IN0 to IN3 are lower than the true terminal voltage, and are different voltage values depending on the elapsed time after the state setting of the first to third electronic switches G1 to G3. Such changes in the terminal voltages of the input terminals IN0 to IN3 are values in which the first to third detection voltages V1, V2, and V3 differ depending on the timing after the state of the first to third electronic switches G1 to G3 is set. That is, it means that the first to third actual cell voltages V1r to V3r acquired in step S5 include an error.

In consideration of such circumstances, in the voltage detection device D according to the present embodiment, the first to third actual cell voltages V1r to acquired in step S5 are based on the correction characteristics stored in advance by the control unit 2. Correct V3r (step S6). That is, the control unit 2 determines the correction coefficients a of the first to third actual cell voltages V1r to V3r by using the correction characteristics shown in FIG. 5 (b).

Then, the control unit 2 multiplies the correction coefficients a for each of the first to third real cell voltages V1r to V3r by the first to third real cell voltages V1r to V3r, respectively, to obtain the first to third real cell voltages. The first to third voltage correction amounts of V1r to V3r are determined. Then, the control unit 2 completes the correction processing of the first to third real cell voltages V1r to V3r by adding the first to third voltage correction amounts to the first to third real cell voltages V1r to V3r, respectively. do.

Further, the control unit 2 executes cell balance control of the first to third battery cells c1 to c3 based on the corrected first to third actual cell voltages V1r to V3r obtained in step S6 (step S7). ). That is, the control unit 2 corrects by setting any one of the first to third electronic switches G1 to G3 to the ON state so that the corrected first to third actual cell voltages V1r to V3r become equal. The completed actual cell voltage is higher than the others. The battery cell with the corrected actual cell voltage is forcibly discharged.

For example, when only the third real cell voltage V3r among the corrected first to third real cell voltages V1r to V3r is higher than the other first and second real cell voltages V1r and V2r, the control unit 2 sets the control unit 2. By setting the third electronic switch G3 corresponding to the third real cell voltage V3r to the ON state, the third battery cell c3 is forced so that the corrected first to third real cell voltages V1r to V3r become equivalent. Discharge.

According to this embodiment, since the 0th to 3rd wiring resistance values R0 to R3 are individually acquired (detected), the battery voltage of the assembled battery B at the time of discharging, that is, the 1st to 3rd battery cells c1 It is possible to detect the first to third real cell voltages V1r to V3r (discharge voltage) of c3 with higher accuracy than before. Therefore, according to the present embodiment, it is possible to realize cell balance control with higher accuracy than before.

The present invention is not limited to the above embodiment, and for example, the following modifications can be considered.
(1) In the above embodiment, the assembled battery B including three battery cells, that is, the first to third battery cells c1 to c3 has been described, but the present invention is not limited thereto. The present invention is also applicable to an assembled battery having a number of cells other than three or a battery composed of a single battery cell.

For example, for a battery (single battery) having one cell number, the actual battery voltage excluding the voltage drop due to the wiring resistance value may be obtained. In this case, although the purpose is not to control the cell balance, the state of the battery (cell) can be grasped more accurately by obtaining the true battery voltage (actual battery voltage) excluding the influence of the wiring resistance value. be able to.

(2) In the above embodiment, the correction processing of the first to third actual cell voltages V1r to V3r is performed in step S7, but the present invention is not limited to this. That is, if the influence of the time constants of the first to third CR filters F0 to F3 can be ignored, or if the first to third CR filters F0 to F3 are not provided, the process of step S7 can be omitted.

(3) In the above embodiment, the 0th to 3rd wiring resistance values R0 to R3 are individually detected for the purpose of improving the accuracy of the cell balance control, but the present invention is not limited thereto. That is, the 0th to 3rd wiring resistance values R0 to R3 may be individually detected for purposes other than improving the accuracy of the cell balance control.

A1 to A3 1st to 3rd voltage detection circuit B group battery CT0 to CT3 0th to 3rd control terminals c1 to c3 1st to 3rd battery cells D Voltage detection device F0 to F3 0th to 3rd CR filters H0 to H3 0th to 3rd connection lines IN0 to IN3 0th to 3rd input terminals r1n to r3n, r1p to r3p Internal resistance G1 to G3 1st to 3rd electronic switches Z0 to Z3 0th to 3rd discharge resistors 1 Voltage detection IC
2 Control unit

Claims (6)

In a voltage detection device including a discharge resistor and an electronic switch, a discharge circuit connected in parallel to the battery, a voltage detection circuit for detecting the voltage of the battery, and a control unit for controlling the electronic switch.
The control unit has a first detection voltage detected by the voltage detection circuit when the electronic switch is set to the ON state, and a second detection voltage detected by the voltage detection circuit when the electronic switch is set to the OFF state. A voltage detection device, characterized in that a wiring resistance value between the voltage detection circuit and the battery is acquired based on the detection voltage. The battery is an assembled battery in which a plurality of battery cells are connected in series.
The discharge circuit is provided for each battery cell, and the discharge circuit is provided for each battery cell.
The control unit is the electronic switch of the discharge circuit corresponding to an even cell having an even order of connection among the plurality of battery cells, and the electronic switch of the discharge circuit corresponding to an odd cell having an odd number of connections in the connection order. The voltage detection according to claim 1, wherein the wiring resistance values between the voltage detection circuit and the plurality of battery cells are obtained by alternately setting the voltage detection circuit to the ON state or the OFF state. Device. The voltage detection device according to claim 2, wherein the control unit acquires an actual battery voltage or a plurality of actual cell voltages excluding the voltage drop caused by the wiring resistance value based on the wiring resistance value. .. The voltage detection device according to claim 3, wherein the control unit determines a correction coefficient according to the wiring resistance value and corrects the actual cell voltage based on the correction coefficient. The voltage detection device according to claim 3 or 4, wherein the control unit executes cell balance control of a plurality of the battery cells based on the actual cell voltage. The voltage detection device according to any one of claims 1 to 5, wherein the control unit acquires the first detection voltage and the second detection voltage at least immediately after startup.

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