JP2022127179A - Voltage detection device - Google Patents

Abstract

To provide a voltage detection device that can detect a discharge voltage more precisely than before.SOLUTION: A voltage detection device includes: a voltage detection circuit that is connected to an electrode of each of a plurality of battery cells connected in series through a connection line and detects a cell voltage of the battery cell; a plurality of discharge circuits that are connected in parallel to the battery cells through the connection line; and a control unit that controls the discharge circuit. The control unit calculates the voltage change quantity due to the connection line on the basis of a reference voltage to be input to the voltage detection circuit from the connection line in the case where even-numbered cells in the order of the serial connection among the plurality of battery cells are discharged and in the case where odd-numbered cells are discharged, and calculates a discharge voltage of the battery cell on the basis of the voltage change quantity and the cell voltage.SELECTED DRAWING: Figure 1

Description

The present invention relates to a voltage detection device.

Patent Document 1 listed below discloses a voltage detection device. This voltage detection device includes a voltage detection section for detecting voltages of a plurality of battery cells as cell voltages, and a plurality of discharge circuits provided corresponding to the plurality of battery cells, wherein the voltage detection section includes a discharge circuit. Corrects the cell voltage when discharging the battery cell based on the past voltage drop characteristics of the discharge circuit (voltage drop coefficient obtained from the test discharge state voltage and non-discharge state voltage of the battery cell) and performs cell balance control based on the corrected cell voltage.

JP 2016-180653 A

By the way, in the above voltage detection device, the cell voltage during discharging of the battery cell is determined based on the voltage drop coefficient obtained from the test discharge state voltage and the non-discharge state voltage of the battery cell, that is, based on a preset fixed value. correct.

However, the internal resistance of the battery, and the harness resistance and contact resistance between the battery cell and the voltage detection unit, etc., vary randomly due to individual differences and deterioration. Voltage (discharge voltage) cannot always be detected accurately. That is, in the background art described above, it is not possible to achieve highly accurate cell balance control of battery cells.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a voltage detecting device capable of detecting a discharge voltage more accurately than the conventional one.

In order to achieve the above object, the present invention provides a first solution for a voltage detection device, which is connected to the electrodes of a plurality of battery cells connected in series via connection lines, and detects the cell voltage of the battery cells. , a plurality of discharge circuits connected in parallel to the battery cells via the connection lines, and a control unit for controlling the discharge circuits, wherein the control unit is based on the reference voltage input to the voltage detection circuit from the connection line when the even-numbered cells and the odd-numbered cells are discharged in the order of series connection among the plurality of battery cells. A method is adopted in which voltage variations due to lines are respectively calculated, and the discharge voltage of the battery cell is calculated based on the voltage variations and the cell voltage.

According to the present invention, as a second solution to the voltage detection device, in the first solution, the controller calculates the voltage change amount for each connection line.

In the present invention, as a third solution to the voltage detection device, in the first or second solution, the controller calculates the discharge voltage by adding the voltage change amount to the cell voltage. Adopt a means of doing.

In the present invention, as a fourth solution to the voltage detection device, in any one of the first to third solutions, a low-pass filter is provided between the connection line and the voltage detection circuit, The control unit calculates the amount of voltage change caused by the connection line and the low-pass filter based on the reference voltage input to the voltage detection circuit through the connection line and the low-pass filter. adopt.

In the present invention, as a fourth solution means related to the voltage detection device, in any one of the first to fourth solution means, the control unit performs cell balance control based on the discharge voltage. adopt.

According to the present invention, as a fifth solution to the voltage detection device, in any one of the first to fifth solutions, the controller calculates the voltage change amount at least immediately after startup. adopt.

ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the voltage detection apparatus which can detect a discharge voltage more correctly than before.

1 is a circuit diagram showing the configuration of a voltage detection device D according to one embodiment of the present invention; FIG. 4 is a flow chart showing the operation of the voltage detection device D according to one embodiment of the present invention; 4 is a circuit diagram showing an example of discharge current in one embodiment of the present invention; FIG. FIG. 4 is a characteristic diagram showing path resistance voltage change amount characteristics in one embodiment of the present invention; FIG. 4 is a waveform diagram showing a method of correcting a detected voltage in one embodiment of the present invention;

An embodiment of the present invention will be described below with reference to the drawings.
A voltage detection device D according to the present embodiment detects an assembled battery B as shown in FIG. This voltage detection device D is mounted on an electric vehicle, such as an electric vehicle or a hybrid vehicle, using a motor as a driving power source together with the assembled battery B, and detects the voltage of the assembled battery B. FIG.

Such a voltage detection device D includes, as shown, 0th to 3rd connection lines H0 to H3, 0th to 3rd filters F0 to F3, 0th to 3rd discharge resistors Z0 to Z4, and a voltage detection IC1. It has Among these components, the voltage detection IC1 includes 0th to 3rd input terminals IN0 to IN3, 0th to 3rd control terminals CT0 to CT3, 1st to 3rd voltage detection circuits A1 to A3, and the 1st ∼ Third switches G1 to G3 and a control unit 2 are provided at least.

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

Note that FIG. 1 shows, for the sake of convenience, that the assembled battery B is provided with 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. Also, the first to third voltage detection circuits A1 to A3 and the first to third switches G1 to G3, which constitute the voltage detection IC1, are provided corresponding to the battery cells. The numbers of A1 to A3 and first to third switches G1 to G3 change 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 in the order of connection. On the other hand, the second battery cell c2 is an even-numbered cell with an even-numbered connection order.

Each of the first to third battery cells c1 to c3 has a predetermined internal resistance as shown. As shown in the figure, this internal resistance exists for each electrode of the first to third battery cells c1 to c3, that is, the positive electrode and the negative electrode, and can change according to the usage condition 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, an internal resistance r2n exists at the negative electrode of the second battery cell c2, and an internal resistance r2p exists at the positive electrode of the second battery cell c2. Furthermore, an internal resistance r3n exists at the negative electrode of the third battery cell c3, and an internal resistance r3p exists at the positive electrode of the third battery cell c3.

Here, in FIG. 1, among the first to third battery cells c1 to c3, the potential of the negative electrode (0th electrode voltage) of the first battery cell c1 is "VH0", and the positive electrode of the first battery cell c1 is The potential of the negative electrode (first electrode voltage) of the second battery cell c2 is "VH1", and the potential of the positive electrode (second electrode voltage) of the second battery cell c2, that is, the negative electrode (second electrode voltage) of the third battery cell c3 is "VH2". , the potential of the positive electrode (third electrode voltage) of the third battery cell c3 is "VH3".

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. Among these 0th to 3rd connection lines H0 to H3, the 0th connection line H0 has one end connected to the negative electrode of the first battery cell c1 and the other end connected to the 0th detection input terminal N0 of the voltage detection device D. Wires connected. The 0th connection line H0 has a 0th wiring impedance R0 as the sum 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 first detection input terminal N1 of the voltage detection device D. It's an electric wire. The first connection line H1 has a first wiring impedance R1 as a sum of its own internal resistance and contact resistance at each end.

The second connection line H2 has one end 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 connected to the second detection input terminal of the voltage detection device D according to the present embodiment. This is the wire connected to N2. The second connection line H2 has a second wiring impedance R2 as the sum of its own internal resistance and contact resistance at each end.

Further, the third connection line H3 is an electric wire having one end connected to the positive electrode of the third battery cell c3 and the other end connected to the third detection input terminal N3 of the voltage detection device D. The third connection line H3 has a third wiring impedance R3 as the sum of its own internal resistance and contact resistance at each end.

The 0th to 3rd filters F0 to F3 are low-pass filters composed of resistors and capacitors as shown. In these 0th to 3rd filters F0 to F3, the resistors all have the same resistance value (filter resistance value R), and the capacitors all have the same capacitance (filter capacitance C). there is

Among these 0th to 3rd filters F0 to F3, the 0th filter F0 has an input terminal connected to the 0th detection input terminal N0 of the voltage detection device D, and an output terminal connected to the 0th input terminal IN0 of the voltage detection IC1. It is connected. The input terminal of the 0th filter F0 is connected (grounded) to GND, which is a reference potential, as shown.

The first filter F1 has an input end connected to the first detection input end N1 of the voltage detection device D, and an output end connected to the first input terminal IN1 of the voltage detection IC1. The second filter F2 has an input end connected to the second detection input end N2 of the voltage detection device D, and an output end connected to the second input terminal IN2 of the voltage detection IC1. Further, the third filter F3 has an input end connected to the third detection input end of the voltage detection device D, and an output end connected to the third input terminal IN3 of the voltage detection IC1.

In the 0th to 3rd filters F0 to F3, the resistors have one end connected to the electrode of each battery cell and the other end connected to one end of the capacitor and each input terminal of the voltage detection IC1. In the 0th to 3rd filters F0 to F3, the capacitors have one ends connected to the other ends of the resistors and input terminals of the voltage detection IC1, and the other ends grounded.

The 0th to 3rd filters F0 to F3 are low-pass filters that remove noise superimposed on the voltages input to the input terminals of the voltage detection IC 1 from the 1st to 3rd battery cells c1 to c3. be. External noise may enter the 0th to 3rd connection lines H0 to H3 that connect the voltage detection device D and the assembled battery B, and the four 0th to 3rd filters F0 to F3 It suppresses 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. Among the 0th to 3rd discharge resistors Z0 to Z4, the 0th discharge resistor Z0 has one end connected to the other end of the 0th connection line H0 and the input end of the 0th filter F0, and the other end to detect voltage. It is connected to the control terminal CT0 of IC1. The first discharge resistor Z1 has one end connected to the other end of the first connection line H1 and the input end of the first filter F1, and the other end connected to the control terminal CT0 of the voltage detection IC1.

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

The voltage detection IC1 has a function of detecting cell voltages (first to third cell voltages Vc1 to Vc3) of the first to third battery cells c1 to c3 and forcibly discharging the first to third battery cells c1 to c3. An integrated circuit comprising at least The operation of the voltage detection IC 1 is controlled by an external control device (not shown), and based on a voltage transmission command input from the control device, the first to third cell voltages Vc1 to the control device. ∼Vc3 and forcibly discharge the first to third battery cells c1 to c3.

Of the 0th to 3rd input terminals IN0 to IN3 in the voltage detection IC1, the 0th input terminal IN0 is connected to the output terminal of the 0th filter F0 and the first input terminal of the first voltage detection circuit A1. there is The first input terminal IN1 is connected to the output end of the first 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 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 filter F3 and the second input end of the third voltage detection circuit A3.

Here, although not shown in FIG. 1, the 0th to 3rd input terminals IN0 to IN3 are connected to the control unit 2 by internal wiring, and the respective voltages of the 0th to 3rd input terminals IN0 to IN3 are , 0th to 3rd reference voltages V0s to V3s. That is, the 0th to 3rd reference voltages V0s to V3s are input to the voltage detection IC1 via the 0th to 3rd connection lines H0 to H3 and the 0th to 3rd filters F0 to F3, respectively.

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.

Among the first to third voltage detection circuits A1 to A3, the first voltage detection circuit A1 has a first input terminal connected to the 0th input terminal IN0 and a second input terminal connected to the first input terminal IN1. It is a voltage amplifier circuit. The first voltage detection circuit A1 outputs to the control section 2 a first detection voltage V1 indicating the inter-terminal voltage between 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 amplifier circuit having a first input terminal connected to the first input terminal IN1 and a second input terminal connected to the second input terminal IN2. The second voltage detection circuit A2 outputs to the control section 2 a second detection voltage V2 indicating the inter-terminal voltage between 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 amplifier circuit having a first input terminal connected to the second input terminal IN2 and a second input terminal connected to the third input terminal IN3. The third voltage detection circuit A3 outputs to the control section 2 a third detection voltage V3 indicating the inter-terminal voltage between the voltage V2 of the second input terminal IN2 and the voltage V3 of the third input terminal IN3.

Here, the first to third voltage detection circuits A1 to A3 are operational amplifiers with extremely high input impedance, and the input impedance can be treated as infinite. Therefore, almost no input current flows through the first to third voltage detection circuits A1 to A3 when detecting the first to third detection voltages V1 to V3.

Such first to third voltage detection circuits A1 to A3 are connected to the positive electrodes and negative electrodes of the first to third battery cells c1 to c3 (a plurality of battery cells) connected in series with the 0th to third connection lines. They are connected via H0 to H3 and zeroth to third filters F0 to F3, respectively, and detect first to third detection voltages V1 to V3 as cell voltages of first to third battery cells c1 to c3, respectively.

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

The second electronic switch G2 has one end connected to the first control terminal CT1 and the other end connected to the second control terminal CT2. When the second electronic switch G2 is turned ON, it connects the other end of the first discharge resistor Z1 and the other end of the second discharge resistor Z2, thereby forcibly discharging the second battery cell c2.

The third electronic switch G3 has one end connected to the second control terminal CT2 and the other end connected to the third control terminal CT3. When the third electronic switch G3 is turned ON, it connects the other end of the second discharge resistor Z2 and the other end of the third discharge resistor Z3, thereby forcibly discharging the third battery cell c3.

Here, the 0th and 1st discharge resistors Z0 and Z1 and the first electronic switch G1 are a series circuit connected in parallel to the first battery cell c1, and constitute the discharge circuit (first discharge circuit) of the present invention. Configure. This first discharge circuit is connected in parallel to the first battery cell c1 via the 0th connection line H0 and the first connection line H1, and the 0th filter F0 and the first filter F1, respectively. The ON state forces the first battery cell c1 to discharge.

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. is doing. This second discharge circuit is connected in parallel to the second battery cell c2 via a first connection line H1 and a second connection line H2 and a first filter F1 and a second filter F2, respectively, and the second electronic switch G2 is The ON state forces the second battery cell c2 to discharge.

Furthermore, 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. is doing. This third discharge circuit is connected in parallel to the third battery cell c3 via a second connection line H2 and a third connection line H3 and a second filter F2 and a third filter F3. The ON state forces the third battery cell c3 to discharge.

Although not shown, current detection circuits are connected in series to the first to third electronic switches G1 to G3 to detect the respective energized currents. That is, a first current detection circuit is connected in series with the first electronic switch G1, a second current detection circuit is connected in series with the second electronic switch G2, and a third current detection circuit is connected with the third electronic switch G3. connected in series.

The current flowing through the first electronic switch G1 is the first discharge current I1 discharged from the first battery cell c1 when the first electronic switch G1 is ON. The current flowing through the second electronic switch G2 is the second discharge current I2 discharged from the second battery cell c2 when the second electronic switch G2 is ON. Also, the current flowing through the third electronic switch G3 is the third discharge current I3 that is discharged from the third battery cell c3 when the third electronic switch G3 is ON.

The controller 2 controls the first to third electronic switches G1 to G3 and detects the first to third discharge voltages V1r to V3r of the first to third battery cells c1 to c3. Although the details will be described later, the control unit 2 controls the first to third detection voltages V1on to V3on and V1off to V3off obtained when the first to third electronic switches G1 to G3 are turned on/off, and the 0th to 3rd reference voltages. First to third discharge voltages V1r to V3r are calculated based on the voltages V0s to V3s.

Here, among the first to third discharge voltages V1r to V3r, the first discharge voltage V1r is the difference between the first electrode voltage VH1 and the 0th electrode voltage VH0 in the discharged state of the first battery cell c1, that is, the This is the inter-electrode voltage when one battery cell c1 is discharged. In other words, the first discharge voltage V1r is the true voltage when the first battery cell c1 is discharged, excluding the effects of the 0th wiring impedance R0, the first wiring impedance R1, and the filter impedances of the 0th and 1st filters F0 and F1. is the inter-electrode voltage of

The second discharge voltage V2r is the difference between the second electrode voltage VH2 and the first electrode voltage VH1 in the discharged state of the second battery cell c2, that is, the voltage between the electrodes when the second battery cell c2 is discharged. In other words, the second discharge voltage V2r is the true voltage when the second battery cell c2 is discharged, excluding the effects of the first wiring impedance R1, the second wiring impedance R2, and the filter impedances of the first and second filters F1 and F2. is the inter-electrode voltage of

Furthermore, the third discharge voltage V3r is the difference between the third electrode voltage VH3 and the second electrode voltage VH2 in the discharged state of the third battery cell c3, that is, the voltage between the electrodes when the third battery cell c3 is discharged. In other words, the third discharge voltage V3r is the true value during discharge of the third battery cell c3 excluding the effects of the second wiring impedance R2, the third wiring impedance R3, and the filter impedances of the second and third filters F2 and F3. is the inter-electrode voltage of

Further, the control unit 2 performs cell balance control for the first to third battery cells c1 to c3 based on the first to third discharge voltages V1r to V3r. That is, the control unit 2 controls the first to third electronic switches G1 to G3 based on the first to third discharge voltages V1r to V3r, thereby controlling the charged states of the first to third battery cells c1 to c3. homogenize.

Next, referring to FIGS. 2 to 5, the operation of the voltage detection device D according to the present embodiment, particularly the acquisition process of the first to third discharge voltages V1r to V3r executed by the control unit 2 (discharge voltage acquisition process). ) will be described in detail.

Immediately after starting the voltage detection device D, the control unit 2 executes the discharge voltage acquisition process shown in the flowchart of FIG. 2 to acquire the first to third discharge voltages V1r to V3r. In this discharge voltage acquisition process, the control unit 2 first sets all the first to third electronic switches G1 to G3 to the OFF state, and acquires the cell voltages of the first to third battery cells c1 to c3 in this state. (step S1). That is, the control unit 2 sets all the first to third battery cells c1 to c3 to the non-discharge state, and obtains the first to third detection voltages V1off to V3off in this state as cell voltages.

Then, the control unit 2 sets only the even-numbered cells in the order of series connection, ie, the second battery cell c2, among the first to third battery cells c1 to c3 to the discharging state, and sets the first to third battery cells c1 to c3 in this state to the discharging state. The cell voltages of cells c1 to c3 are obtained (step S2). That is, the control unit 2 sets the second electronic switch G2 to the ON state and the first and third electronic switches G1 and G3 to the OFF state among the first to third electronic switches G1 to G3, and sets the third electronic switch G1 to G3 to the OFF state. 1st to 3rd second detection voltages V1off_2, V2on, and V3off_2 are obtained.

When only the second electronic switch G2 is set to the ON state in this way, as shown in FIG. 3, a second discharge current I2 flows from the positive electrode of the second battery cell c2 to the negative electrode of the second battery cell c2. . This second discharge current I2 flows via the second wiring impedance R2→the second discharge resistor Z2→the second electronic switch G2→the first discharge resistor Z1→the first wiring impedance R1.

Then, the control unit 2 sets only the second battery cell c2 (even cell) to the discharge state, and the absolute values of the second cell voltage change amount ΔV2 and the first and third cell voltage change amounts ΔV12 and ΔV32 in this state |ΔV2|, |ΔV12|, and |ΔV32| are calculated (step S3). That is, the control unit 2 determines the absolute values |ΔV2|, |ΔV12| |ΔV32| is calculated.

|ΔV2|=|V2off−V2on| (1)
|ΔV12|=|V1off−V1off_2| (2)
|ΔV32|=|V3off−V3off_2| (3)

The above formula (1) is the total resistance value of the first wiring impedance R1 and the second wiring impedance R2 with respect to the difference voltage between the second electrode voltage VH2, which is the voltage between the electrodes of the second battery cell c2, and the first electrode voltage VH1. and voltage change (voltage drop or voltage rise) due to each resistance value of the first discharge resistor Z1 and the second discharge resistor Z2.

On the other hand, the formula (2) shows the first voltage change amount ΔV(r1) caused by the first wiring impedance R1 (first connection line H1) with respect to the voltage difference between the second electrode voltage VH2 and the first electrode voltage VH1. ing. Equation (3) expresses the third voltage change amount ΔV(r3) caused by the third wiring impedance R3 (third connection line H3) with respect to the voltage difference between the second electrode voltage VH2 and the first electrode voltage VH1. ing.

Subsequently, the control unit 2 sets only the odd-numbered cells in the order of series connection, ie, the first and third battery cells c1 and c3, to the discharging state among the first to third battery cells c1 to c3. The cell voltages of the first to third battery cells c1 to c3 are obtained (step S4). That is, the control unit 2 sets the first and third electronic switches G1 and G3 of the first to third electronic switches G1 to G3 to the ON state and the second electronic switch G2 to the OFF state. First to third detection voltages V1on, V2off_13, and V3on are obtained.

When only the first and third electronic switches G1 and G3 are set to the ON state in this manner, a first discharge current I1 (not shown) that flows from the positive electrode of the first battery cell c1 to the negative electrode of the first battery cell c1 flows. This first discharge current I1 flows via the first wiring impedance R1→the first discharge resistor Z1→the first electronic switch G1→the 0th discharge resistor Z0→the 0th wiring impedance R0.

Also, in this case, a third discharge current I3 (not shown) flows from the positive electrode of the third battery cell c3 to the negative electrode of the third battery cell c3. This third discharge current I3 flows via the third wiring impedance R3→the third discharge resistor Z3→the third electronic switch G3→the second discharge resistor Z2→the second wiring impedance R2.

Then, the control unit 2 determines the absolute values |ΔV1 |, |ΔV213|, and |ΔV3| are calculated (step S5). That is, the control unit 2 calculates the absolute values |ΔV1|, |ΔV213|, |ΔV3| do.

|ΔV1|=|V1off−V1on| (4)
|ΔV213|=|V2off−V2off_13| (5)
|ΔV3|=|V3off−V3on| (6)

The above formula (4) expresses the total resistance value of the 0th wiring impedance R0 and the 1st wiring impedance R1 with respect to the inter-electrode voltage Vd1 of the first battery cell c1, that is, the difference voltage between the first electrode voltage VH1 and the 0th electrode voltage VH0. and the amount of voltage change (amount of voltage drop or amount of voltage rise) caused by each resistance value of the 0th discharge resistor Z0 and the first discharge resistor Z1.

Further, the formula (6) is the total resistance of the second wiring impedance R2 and the third wiring impedance R3 with respect to the inter-electrode voltage Vd3 of the third battery cell c3, that is, the difference voltage between the third electrode voltage VH3 and the second electrode voltage VH2. and the amount of voltage change (amount of voltage drop or amount of voltage rise) due to each resistance value of the second discharge resistor Z2 and the third discharge resistor Z3.

On the other hand, the above equation (5) expresses the second voltage change amount ΔV(r2) caused by the second wiring impedance R2 (second connection line H2) with respect to the difference voltage between the third electrode voltage VH3 and the second electrode voltage VH2. showing.

That is, by setting only the even-numbered cells to the discharge state, the first voltage change amount ΔV(r1) caused by the first wiring impedance R1 (first connection line H1) and the third wiring impedance R3 (third connection line H3) are reduced. A third voltage change amount ΔV(r3) caused by the second wiring impedance R2 (the second connection line H2) can be obtained by setting only the odd-numbered cells to the discharge state. is obtained.

The control unit 2 calculates the absolute values |ΔV2|, |ΔV12| , |ΔV32| and the first to third cell voltage change amounts and the absolute values |ΔV1|, |ΔV213|, |ΔV3| A path resistance voltage change characteristic L indicating the relationship between the first to third detection voltages V1off to V3off (cell voltages) relating to ~c3 is obtained (step S6).

Here, the absolute values |ΔV2|, |ΔV12|, |ΔV32|, |ΔV1|, |ΔV213|, |ΔV3| be. That is, the path resistance voltage change characteristic L is represented by a straight line as shown in FIG. The control unit 2 obtains the slope of the path resistance voltage change characteristic L (straight line) based on the formulas (1) to (6).

Thus, the path resistance voltage change characteristics L of the absolute values |ΔV2|, |ΔV12|, |ΔV32|, |ΔV1|, |ΔV213|, |ΔV3|, that is, the absolute values |ΔV2|, |ΔV12|, After acquiring the cell voltage dependent characteristics of |ΔV32|, |ΔV1|, |ΔV213|, and |ΔV3|, the control unit 2 determines whether or not a discharge instruction is input from a host control device such as a vehicle ECU (step S7).

If the determination in step S7 is "Yes", that is, if the discharge instruction is input, the control unit 2 acquires the 0th to 3rd reference voltages V00 to V30 at time t0 (step S8). That is, the control unit 2 A/D-converts the 0th to 3rd reference voltages V00 to V30 at the first time t0 to obtain the digital values of the 0th to 3rd reference voltages V0s to V3s (0th to 3rd Reference voltage data V00 to V30) are acquired.

As described above, the 0th to 3rd filters F0 to F3 (low-pass filters) are provided between the 0th to 3rd connection lines H0 to H3 and the 0th to 3rd input terminals IN0 to IN3, respectively. Due to the integrating action of the 0th to 3rd filters F0 to F3 and the 0th to 3rd wiring impedances R0 to R3 of the 0th to 3rd connection lines H0 to H3, the 0th to 3rd reference voltages V0s~ V3s fluctuates with time in synchronization with the ON/OFF operations of the first to third electronic switches G1 to G3.

FIG. 5 shows a case where only the second electronic switch G2 (even switch) is ON/OFF operated (during even cell discharge) and only the first and third electronic switches G1 and G3 (odd switch) are ON/OFF operated. As an example, time changes of the first reference voltage data V1s and the second reference voltage data V2s in the case of discharging the odd-numbered cells are shown.

As shown in FIG. 5, only the second electronic switch G2 (even-numbered switch) is turned ON (even-numbered cell discharging state) for a first fixed period T1, and turned OFF for a second period T2 (even-numbered cell non-discharging state). , the first reference voltage data V1s gradually increases while fluctuating up and down, and the second reference voltage data V2s gradually falls while fluctuating up and down.

On the other hand, only the first and third electronic switches G1 and G3 (odd-numbered switches) are turned ON (odd-numbered cells discharge state) for the first fixed period T1, and turned OFF (odd-numbered cells non-discharged) for the second period T2. When the setting is repeated, the first reference voltage data V1s gradually drops while fluctuating up and down, and the second reference voltage data V2s gradually rises while fluctuating up and down.

Further, the first reference voltage data V1s is obtained by using the first electrode voltage VH1, which is the negative electrode voltage of the second battery cell c2, as a reference voltage (first reference voltage), and the voltage difference from the first reference voltage is the integral action. is a fluctuating voltage that changes from moment to moment in accordance with the discharge states of the second battery cell c2 and the first and third battery cells c1 and c3.

On the other hand, the second reference voltage data V2s is obtained by using the second electrode voltage VH2, which is the positive electrode voltage of the second battery cell c2, as a reference voltage (second reference voltage), and the voltage difference from the second reference voltage is the integral action. is a fluctuating voltage that changes from moment to moment in accordance with the discharge states of the second battery cell c2 and the first and third battery cells c1 and c3.

If the determination in step S7 is "No", that is, if the discharge instruction is not input from the host control device, the control unit 2 operates the first to third electronic switches G1 to G3 in the same manner as in step S1 described above. is set to the OFF state (step S9), and the acquisition process of the first to third discharge voltages V1r to V3r is completed.

Then, when step S8 described above is completed, the control unit 2 determines whether the number of battery cells to be discharged based on the discharge instruction is an even number (even number cells), an odd number (odd number cells), or all numbers (odd number cells and even number cells). (step S10). Then, if the determination in step S10 is "even", the control unit 2 acquires the 0th to 3rd reference voltage data V0x to V3x at times t1 to t4 during the even cell discharge (step S11). Note that "x" is a number from 1 to 4 corresponding to times t1 to t4.

Then, the control unit 2 calculates the difference between the 0th to 3rd reference voltage data V0x to V3x and the 0th to 3rd reference voltages V00 to V30 at the time t0 acquired in step S8 as the 0th to 3rd correction voltage ΔV0x. ˜ΔV3x (step S12).

That is, in this step S12, the control unit 2 first converts the voltages of the 0th to 3rd detection input terminals N0 to N3 (0th to 3rd input voltages V0in to V3in) into the following equations (7) and (8). calculated based on

V1in = V10 + |ΔV(r1)| (7)
V2in = V20 - |ΔV(r2)| (8)

Then, the control unit 2 calculates the zeroth to third reference voltages V0x′ to V3x′ at times t1′ to t4′ when the first to third battery cells c1 to c3 transition from the discharging state to the non-discharging state by the following formula ( 9) Calculate based on (10). In these formulas (9) and (10), "CR" is the product of the filter resistance value R and the filter capacitance C of the 0th to 3rd filters F0 to F3. "T1" is the above-described first fixed period T1, that is, the discharge period of even-numbered cells in which discharge/non-discharge are repeated at a predetermined repetition period T.

V1x'=(V1in-V10).{1-exp(-T1/CR)}+V10 (9)
V2x'=(V2in-V20).{1-exp(-T1/CR)}+V20 (10)

Then, the control unit 2 calculates the zeroth to third reference voltages V0x to V3x at times t1 to t4 when the first to third battery cells c1 to c3 transition again from the non-discharging state to the discharging state using the following formula (11), Calculated based on (12). Note that "T2" in equations (11) and (12) is a non-discharge period of an even-numbered cell in which discharge/non-discharge are repeated at a predetermined repetition cycle T.

V1x=(V10-V1x').{1-exp(-T2/CR)}+V1x' (11)
V2x=(V20-V2x').{1-exp(-T2/CR)}+V2x' (12)

Then, based on the following expressions (13) and (14), the control unit 2 calculates Voltage differences between the 0th to 3rd reference voltages V0x to V3x are calculated as 0th to 3rd correction voltages ΔV0x to ΔV3x.

These 0th to 3rd correction voltages ΔV0x to ΔV3x are fluctuations of the 0th to 3rd reference voltages V0x to V3x caused by the impedances of the 0th to 3rd connection lines H0 to H3 and the 0th to 3rd filters F0 to F3. Equivalent to quantity. That is, the control unit 2 calculates the amount of voltage change caused by the impedance of the 0th to 3rd connection lines H0 to H3 and the 0th to 3rd filters F0 to F3 for each of the 0th to 3rd connection lines H0 to H3. .

ΔV1x = V10 - V1x (13)
ΔV2x = V20 - V2x (14)

Then, based on the following equations (15) to (17), the control unit 2 determines the correction voltages at times t1 to t4 for the first to third detection voltages V1off to V3off acquired in step S1, that is, the first to 3 Calculate discharge voltages V1xr to V3xr (step S13). That is, the control unit 2 adds the 0th to 3rd correction voltages ΔV0x to ΔV3x (voltage change amounts) to the 1st to 3rd detection voltages V1off to V3off (cell voltages) to obtain the 1st to 3rd discharge voltages V1xr. ˜V3xr is calculated.

V1xr = V1off - ΔV1x (15)
V2xr = V2on + ΔV2x + ΔV1x (16)
V3xr = V3off - ΔV2x (17)

On the other hand, if the determination in step S10 is "odd", the control unit 2 acquires the 0th to 3rd reference voltage data V0y to V3y at times t5 to t8 during odd cell discharge (step S14). Note that "y" is a number from 5 to 8 corresponding to times t5 to t8.

Then, the control unit 2 converts the differential voltages between the 0th to 3rd reference voltage data V0y to V3y and the 0th to 3rd reference voltages V00 to V30 at the time t0 acquired in step S8 into the 0th to 3rd correction voltages. ΔV0y to ΔV3y are calculated (step S15).

In this step S15, the control unit 2 calculates the voltages of the 0th to 3rd detection input terminals N0 to N3 (0th to 3rd input voltages V0in to V3in) based on the following equations (18) to (21). . Then, the control unit 2 calculates the zeroth to third reference voltages V0y' to V3y' at times t5' to t8' when the first to third battery cells c1 to c3 transition from the discharge state to the non-discharge state by the following formula ( 22) Calculate based on (25).

V0in = V00 + |ΔV(r0)| (18)
V1in = V10 - |ΔV(r1)| (19)
V2in = V20 + |ΔV(r2)| (20)
V3in = V30 - |ΔV(r3)| (21)

In these equations (22) to (25), "CR" is the product of the filter resistance value R and the filter capacitance C of the 0th to 3rd filters F0 to F3. "T1" is the above-described first fixed period T1, that is, the discharge period of the odd-numbered cells in which discharge/non-discharge are repeated at a predetermined repetition period T.

V0y'=(V0in-V00).{1-exp(-T1/CR)}+V00 (22)
V1y'=(V1in-V10).{1-exp(-T1/CR)}+V10 (23)
V2y'=(V2in-V20).{1-exp(-T1/CR)}+V20 (24)
V3y'=(V3in-V30).{1-exp(-T1/CR)}+V30 (25)

Then, the control unit 2 calculates the zeroth to third reference voltages V0y to V3y at times t5 to t8 when the first to third battery cells c1 to c3 transition again from the non-discharging state to the discharging state by the following equations (26) to Calculated based on (29). Note that "T2" in equations (26) to (29) is the non-discharge period of odd-numbered cells in which discharge/non-discharge are repeated at a predetermined repetition period T.

V0y=(V00-V0y').{1-exp(-T2/CR)}+V0y' (26)
V1y=(V10-V1y').{1-exp(-T2/CR)}+V1y' (27)
V2y=(V20-V2y').{1-exp(-T2/CR)}+V2y' (28)
V3y=(V30-V3y').{1-exp(-T2/CR)}+V3y' (29)

Then, based on the following equations (30) to (33), the control unit 2 calculates Voltage differences between the 0th to 3rd reference voltages V0y to V3y are calculated as 0th to 3rd correction voltages ΔV0y to ΔV3y.

These 0th to 3rd correction voltages ΔV0y to ΔV3y are fluctuations of the 0th to 3rd reference voltages V0y to V3y caused by the impedances of the 0th to 3rd connection lines H0 to H3 and the 0th to 3rd filters F0 to F3. Equivalent to quantity. That is, the control unit 2 calculates the amount of voltage change caused by the impedance of the 0th to 3rd connection lines H0 to H3 and the 0th to 3rd filters F0 to F3 for each of the 0th to 3rd connection lines H0 to H3. .

ΔV0y = V00 - V0y (30)
ΔV1y = V10 - V1y (31)
ΔV2y = V20 - V2y (32)
ΔV3y = V30 - V3y (33)

Then, based on the following equations (34) to (36), the control unit 2 determines the correction voltages at times t5 to t8 for the first to third detection voltages V1off to V3off acquired in step S1, that is, the first to third 3 Discharge voltages V1yr to V3yr are calculated (step S16). That is, the control unit 2 adds the 0th to 3rd correction voltages ΔV0y to ΔV3y (voltage change amounts) to the 1st to 3rd detection voltages V1off to V3off (cell voltages) to obtain the 1st to 3rd discharge voltages V1yr. ˜V3yr is calculated.

V1yr = V1on + ΔV1y + ΔV0y (34)
V2yr = V2off - ΔV2y - ΔV1y (35)
V3yr = V3on + ΔV3y + ΔV2y (36)

Further, if the determination in step S10 is "all", the control unit 2 acquires the 0th to 3rd reference voltage data V0z to V3z at times t1 to t8 during all-cell discharge (step S17). Note that "z" is a number from 1 to 8 corresponding to times t1 to t8.

Then, the control unit 2 converts the differential voltages between the 0th to 3rd reference voltage data V0z to V3z and the 0th to 3rd reference voltages V00 to V30 at the time t0 acquired in step S8 into the 0th to 3rd correction voltages. ΔV0z to ΔV3z are calculated (step S18). It should be noted that the processing contents of step S18 and the processing contents of step S19 are a combination of the above-described even (even cell) processing and odd (odd cell) processing. Therefore, detailed description is omitted.

According to this embodiment, the first to third discharge voltages V1xr to Since V3xr, V1yr to V3yr, and V1zr to V3zr are calculated, the first to third discharge voltages V1xr to V3xr, V1yr to V3yr, and V1zr to V3zr can be obtained more accurately than conventionally.

That is, according to the present embodiment, since the first to third discharge voltages V1xr to V3xr, V1yr to V3yr, and V1zr to V3zr obtained by the controller 2 are more accurate than the conventional one, the controller 2 is more accurate than the conventional one. It is possible to perform high cell balance control.

It should be noted that the present invention is not limited to the above-described embodiments, and for example, the following modifications are conceivable.
(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 to this. The present invention can also be applied to assembled batteries having cells other than three. Also, in the above embodiment, a lithium ion battery is mentioned as an example of the assembled battery B, but the assembled battery B is not limited to a lithium ion battery.

(2) In the above embodiment, in addition to the wiring impedance of the 0th to 3rd connection lines H0 to H3, the 1st to 3rd filter impedances (filter impedances) of the 0th to 3rd filters F0 to F3 are also excluded. Although the third discharge voltages V1xr-V3xr, V1yr-V3yr, and V1zr-V3zr are obtained, the present invention is not limited thereto.

As the circuit configuration of the voltage detection device for detecting each cell voltage of the assembled battery B, there is a device that does not include a low-pass filter such as the 0th to 3rd filters F0 to F3. The discharge voltage of each battery cell may be obtained so as to exclude only the influence of wiring impedance of a plurality of connection lines such as .

(3) In the above embodiment, the 0th to 3rd reference voltage data V0x to V3x are acquired for the times t1 to t4 during the discharge of the even cells, and the 0th to 3rd reference voltages are obtained for the times t5 to t8 during the discharge of the odd cells. Although the data V0y to V3y are obtained and the 0th to 3rd reference voltage data V0z to V3z are obtained for the times t1 to t8 during all-cell discharge, the present invention is not limited to this.

That is, the number of times to acquire the 0th to third reference voltage data V0x to V3x during even cell discharge is not limited to four, and the number of times to acquire the 0th to third reference voltage data V0y to V3y during odd cell discharge. is not limited to four. Further, the number of times for acquiring the 0th to 3rd reference voltage data V0z to V3z during all-cell discharge is not limited to eight.

It is preferable that the number of times is as large as possible in order to improve the accuracy of the 0th to 3rd correction voltages ΔV0x to ΔV3x, ΔV0y to ΔV3y, and ΔV0z to ΔV3z. In addition, the number of times for obtaining the 0th to 3rd reference voltage data V0x to V3x during even cell discharge and the number of times for obtaining 0th to 3rd reference voltage data V0y to V3y during odd cell discharge need to be the same number. no.

A1 to A3 1st to 3rd voltage detection circuits B assembled battery CT0 to CT3 0th to 3rd control terminals c1 to c3 1st to 3rd battery cells D voltage detector F0 to F3 0th to 3rd filters H0 to H3 0th to 3rd connection lines IN0 to IN3 0th to 3rd input terminals G1 to G3 1st to 3rd electronic switches N0 to N3 0th to 3rd detection input terminals r1n to r3n, r1p to r3p Internal resistances Z0 to Z3 0th to 3rd discharge resistors 1 voltage detection IC
2 control unit

Claims (6)

a voltage detection circuit that is connected to electrodes of a plurality of battery cells connected in series via a connection line and detects a cell voltage of each of the battery cells; and a voltage detection circuit that is connected in parallel to the battery cells via the connection line. In a voltage detection device comprising a plurality of discharge circuits and a control unit that controls the discharge circuits,
The control unit
When the even-numbered cells in the order of series connection among the plurality of battery cells are discharged, and when the odd-numbered cells are discharged, the voltage detection circuit is applied to the connection line based on the reference voltage input from the connection line to the voltage detection circuit. 1. A voltage detection device, wherein a voltage change amount caused by each of the voltage changes is calculated, and a discharge voltage of the battery cell is calculated based on the voltage change amount and the cell voltage. 2. The voltage detection device according to claim 1, wherein the control unit calculates the voltage change amount for each connection line. 3. The voltage detection device according to claim 1, wherein the control unit calculates the discharge voltage by adding the voltage change amount to the cell voltage. A low-pass filter is provided between each of the connection lines and the voltage detection circuit,
The control unit calculates the amount of voltage change caused by the connection line and the low-pass filter based on the reference voltage input to the voltage detection circuit via the connection line and the low-pass filter. The voltage detection device according to any one of claims 1 to 3. The voltage detection device according to any one of claims 1 to 4, wherein the control section performs cell balance control based on the discharge voltage. The voltage detection device according to any one of claims 1 to 5, wherein the control unit calculates the voltage change amount at least immediately after startup.

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