Voltage detection device

Abstract

To provide a voltage detection device capable of detecting a cell voltage more accurately than before even when a path resistance value is large.SOLUTION: A voltage detection device includes a plurality of discharge circuits respectively connected in parallel to a plurality of battery cells via predetermined voltage detection lines and configured to equalize and discharge the battery cells, and a voltage detection circuit configured to detect cell voltages of the battery cells based on a negative terminal voltage and a positive terminal voltage respectively input to a plurality of input terminals via the voltage detection lines. The voltage detection circuit acquires the negative terminal voltage and the positive terminal voltage at the time of equalizing discharge, estimates a voltage drop amount caused by the voltage detection line based on the negative terminal voltage and the positive terminal voltage, and detects the cell voltage by correcting the negative terminal voltage and the positive terminal voltage based on the voltage drop amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a voltage detection device. [Background technology]

[0002] Patent Document 1 listed below discloses a battery monitoring device that can detect the state of a wiring section connecting a battery pack and the battery monitoring device. This battery monitoring device includes a plurality of wires, one end of which is connected to each of a plurality of unit batteries and the other end of which is a branch line, and among the wires connected to the positive and negative sides of the unit batteries, the positive branch line and the negative branch line are defined as a first wire pair and the positive branch line and the negative branch line are defined as a second wire pair, an equalization switch provided between the first wire pair, a first voltage detection unit provided between the first wire pair, an equalization circuit that equalizes the voltages of the unit batteries by discharging when the equalization switch is turned on based on the voltage detection result by the first voltage detection unit, and a second voltage detection unit provided between the second wire pair and that detects the voltages of the unit batteries when the equalization switch is on and off. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-050870 Summary of the Invention [Problem to be solved by the invention]

[0004] However, such background art has a problem in that when the resistance value of the wiring (path resistance value) is large, the cell voltage cannot be detected with high accuracy.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a voltage detection device that can detect cell voltages more accurately than conventional devices even when the path resistance value is large. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides, as a first solution relating to a voltage detection device, a voltage detection device including a plurality of discharge circuits each connected in parallel to a plurality of battery cells via predetermined voltage detection lines and causing the battery cells to undergo equalized discharge, and a voltage detection circuit that detects the cell voltages of the battery cells based on the negative terminal voltage and the positive terminal voltage input to a plurality of input terminals via the voltage detection lines, wherein the voltage detection circuit acquires the negative terminal voltage and the positive terminal voltage during equalized discharge, estimates the amount of voltage drop caused by the voltage detection lines based on the negative terminal voltage and the positive terminal voltage, and detects the cell voltage by correcting the negative terminal voltage and the positive terminal voltage based on the amount of voltage drop.

[0007] The present invention provides a second solution related to the voltage detection device according to the first solution, in which the voltage detection circuit estimates the amount of voltage drop according to the temperature of the voltage detection line.

[0008] The present invention employs a third solution related to a voltage detection device in the first or second solution, in which the voltage detection circuit acquires the negative terminal voltage and the positive terminal voltage when discharge is ON and when discharge is OFF. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a voltage detection device that can detect cell voltages with higher accuracy than conventional devices even when the path resistance value is large. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration of a voltage detection device according to an embodiment of the present invention; [Figure 2] 4 is a flowchart showing the operation of the voltage detection device according to one embodiment of the present invention. [Figure 3]3 is a waveform diagram showing the operation of the voltage detection device according to the embodiment of the present invention. FIG. [Figure 4] 1 is a first characteristic diagram illustrating the operation of a voltage detection device according to an embodiment of the present invention. [Figure 5] FIG. 4 is a second characteristic diagram showing the operation of the voltage detection device according to one embodiment of the present invention. [Figure 6] FIG. 10 is a third characteristic diagram illustrating the operation of the voltage detecting device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the voltage detection device A according to this embodiment is a device for detecting the voltage of a battery pack B. As shown in the figure, the battery pack B is configured by connecting a plurality of battery cells b1 to b3 in series, and supplies DC power to a load (not shown). This battery pack B is an in-vehicle battery, such as a well-known lithium-ion battery.

[0012] In this embodiment, for the sake of simplicity, the battery pack B will be described as having three cells, but the number of cells is not limited to three. A typical battery pack for vehicle use has several tens of cells (for example, 72 cells). The present invention does not limit the number of cells as long as the number is two or more.

[0013] Of the three battery cells b1 to b3, the positive electrode of the first battery cell b1 is connected to the negative electrode of the second battery cell b2. The positive electrode of the second battery cell b2 is connected to the negative electrode of the third battery cell b3. The negative electrode of the first battery cell b1 is the negative electrode of the battery pack B as shown in the figure, and the positive electrode of the third battery cell b3 is the positive electrode of the battery pack B.

[0014] The three battery cells b1 to b3 each have an output voltage (cell voltage) according to its state of charge. That is, of the three battery cells b1 to b3, the first battery cell b1 (Cell1, odd-numbered cell) has a first cell voltage Vo(3) according to its state of charge, the second battery cell b2 (Cell2, even-numbered cell) has a second cell voltage Vo(2) according to its state of charge, and the third battery cell b3 (Cell3, odd-numbered cell) has a third cell voltage Vo(1) according to its state of charge.

[0015] These three battery cells b1 to b3 are connected in series in a row, so the first battery cell b1 is the battery cell with the lowest potential, the second battery cell b2 is the battery cell with the intermediate potential, and the third battery cell b3 is the battery cell with the highest potential. The output voltage (battery voltage) of battery pack B is the sum of the first cell voltage Vo(3), the second cell voltage Vo(2), and the third cell voltage Vo(1).

[0016] Such a battery pack B is connected to a voltage detection device A by four voltage detection lines L0 to L3 as shown in the figure. That is, of the four voltage detection lines L0 to L3, the 0th voltage detection line L0 has one end connected to the negative terminal of the first battery cell b1 and the other end connected to the 0th input terminal T0 of the voltage detection device A.

[0017] The first voltage detection line L1 is connected to the positive terminal of the first battery cell b1 (the negative terminal of the second battery cell b2) at one end and to the first input terminal T1 of the voltage detection device A at the other end.

[0018] The second voltage detection line L2 has one end connected to the positive terminal of the second battery cell b2 (the negative terminal of the third battery cell b3) and the other end connected to the second input terminal T2 of the voltage detection device A. Furthermore, the third voltage detection line L3 has one end connected to the positive terminal of the third battery cell b3 and the other end connected to the third input terminal T3 of the voltage detection device A.

[0019] Each of these four voltage detection lines L0 to L3 has its own parasitic resistance (path resistance value). That is, the zeroth voltage detection line L0 has the zeroth path resistance value Rs0, the first voltage detection line L1 has the first path resistance value Rs1, the second voltage detection line L2 has the second path resistance value Rs2, and the third voltage detection line L3 has the third path resistance value Rs3.

[0020] In addition to the four input terminals T0 to T3 described above, the voltage detection device A according to this embodiment includes four discharge resistors H0 to H3 and a voltage detection circuit C. Furthermore, the voltage detection circuit C includes three discharge switches SW1 to SW3 as shown in the figure.

[0021] 1 shows three ON resistors D1 to D3 connected in series to the three discharge switches SW1 to SW3, respectively, which are parasitic resistances of the three discharge switches SW1 to SW3. That is, the three ON resistors D1 to D3 are parasitic resistances when the three discharge switches SW1 to SW3 are set to the ON state (closed state).

[0022] Of the four discharge resistors H0 to H3, the 0th discharge resistor H0 has a predetermined resistance value (0th discharge resistance value Rd0), one end is connected to the 0th input terminal T0, and the other end is connected to the first contact of the first discharge switch SW1.

[0023] The first discharge resistor H1 has a predetermined resistance value (first discharge resistance value Rd1), one end is connected to the first input terminal T1, and the other end is connected to one end of the first ON resistor D1 and the first contact of the second discharge switch SW2.

[0024] The second discharge resistor H2 has a predetermined resistance value (second discharge resistance value Rd2), one end connected to the second input terminal T2, and the other end connected to one end of the second ON resistor D2 and the first contact of the third discharge switch SW3. The third discharge resistor H3 has a predetermined resistance value (third discharge resistance value Rd3), one end connected to the third input terminal T3, and the other end connected to one end of the third ON resistor D3.

[0025] Of the three discharge switches SW1 to SW3, the first discharge switch SW1 is an open / close switch (electronic switch) that is set to an ON state (closed state) or an OFF state (open state) by a control unit (not shown) provided in the voltage detection circuit C, and its first contact is connected to the other end of the 0th discharge resistor H0, and its second contact is connected to the other end of the first ON resistor D1.

[0026] The second discharge switch SW2 is an open / close switch (electronic switch) that is set to the ON state (closed state) or the OFF state (open state) by the control unit (not shown), and its first contact is connected to the other end of the first discharge resistor H1, and its second contact is connected to the other end of the second ON resistor D2.

[0027] The third discharge switch SW3 is an open / close switch (electronic switch) that is also set to the ON state (closed state) or the OFF state (open state) by a control unit (not shown), and its first contact is connected to the other end of the second discharge resistor H2, and its second contact is connected to the other end of the third ON resistor D3.

[0028] Of these zeroth to third discharge resistors H0 to H3 and first to third discharge switches SW1 to SW3, the zeroth discharge resistor H0, the first discharge resistor H1, the first ON resistor D1, and the first discharge switch SW1 constitute a first discharge circuit (odd-numbered discharge circuit) connected in parallel to the first battery cell b1 (odd-numbered cell). The first discharge circuit forcibly discharges the first battery cell b1 when the first discharge switch SW1 is set to the ON state.

[0029] The first discharge resistor H1, the second discharge resistor H2, the second ON resistor D2, and the second discharge switch SW2 constitute a second discharge circuit (even discharge circuit) connected in parallel to the second battery cell b2 (even cell). When the second discharge switch SW2 is set to the ON state, a discharge current I flows through the second discharge circuit, forcibly discharging the second battery cell b2.

[0030] Such first to third discharge circuits are provided to equalize the states of charge of the first to third battery cells b1 to b3, that is, to equalize and discharge the first to third battery cells b1 to b3.

[0031] For example, when the second reference cell voltage V2(2) among the first to third reference cell voltages V2(1) to V2(3) is higher than the first reference cell voltage V2(1) and the third reference cell voltage V2(3), the charging of the second battery cell b2 (even cell) is more advanced than the charging of the first battery cell b1 and the third battery cell b3.

[0032] In order to correct this imbalance in the state of charge of the second battery cell b2 (even cell), the second discharge circuit forcibly discharges (equalizes) the second battery cell b2 (even cell), thereby equalizing the state of charge of the second battery cell b2 (even cell) with the states of charge of the first battery cell b1 and the third battery cell b3.

[0033] Furthermore, the second discharge resistor H2, the third discharge resistor H3, the third ON resistor D3, and the third discharge switch SW3 constitute a third discharge circuit (odd-numbered discharge circuit) connected in parallel to the third battery cell b3 (odd-numbered cell). The third discharge circuit forcibly discharges the third battery cell b3 when the third discharge switch SW3 is set to the ON state.

[0034] The voltage detection circuit C is a semiconductor integrated circuit (IC) that detects the above-mentioned first cell voltage Vo(1), second cell voltage Vo(2), and third cell voltage Vo(3) based on the first to third reference cell voltages V2(1) to V2(3) input from the battery pack B via four voltage detection lines L0 to L3.

[0035] The 0th to 4th voltage detection lines L0 to L3 each have the 0th path resistance value Rs0, the first path resistance value Rs1, the second path resistance value Rs2, and the third path resistance value Rs3, so the first to third reference cell voltages V2(1) to V2(3) are different voltages from the 1st cell voltage Vo(1), the 2nd cell voltage Vo(2), and the 3rd cell voltage Vo(3) due to the influence of the 0th path resistance value Rs0, the 1st path resistance value Rs1, the 2nd path resistance value Rs2, and the 3rd path resistance value Rs3.

[0036] That is, the voltage at the 0th input terminal T0 in the voltage detection device A, i.e., the 0th terminal voltage VH0, is the negative terminal voltage of the first battery cell b1, which is different from the negative electrode voltage of the first battery cell b1 due to the voltage drop caused by the 0th path resistance value Rs0.

[0037] Furthermore, the voltage of the first input terminal T1, i.e., the first terminal voltage VH1, is the positive terminal voltage of the first battery cell b1 and the negative terminal voltage of the second battery cell b2, which is different from the positive electrode voltage of the first battery cell b1 (the negative electrode voltage of the second battery cell b2) due to the influence of the voltage drop caused by the first path resistance value Rs1.

[0038] Furthermore, the voltage of the second input terminal T2, i.e., the second terminal voltage VH2, is the negative terminal voltage of the second battery cell b2 and the positive terminal voltage of the third battery cell b3, which is different from the positive electrode voltage of the second battery cell b2 (the negative electrode voltage of the third battery cell b3) due to the influence of the voltage drop caused by the second path resistance value Rs2.

[0039] Furthermore, the voltage of the third input terminal T3, i.e., the third terminal voltage VH3, is the positive terminal voltage of the third battery cell b2, which is different from the positive electrode voltage of the third battery cell b3 due to the voltage drop caused by the third path resistance value Rs3.

[0040] As will be described in detail later, the voltage detection circuit C accurately estimates the zeroth path resistance value Rs0, the first path resistance value Rs1, the second path resistance value Rs2, and the third path resistance value Rs3 by controlling the ON / OFF of the first to third discharge switches SW1 to SW3.

[0041] In addition, the voltage detection circuit C corrects the first to third reference cell voltages V2(1) to V2(3) based on the estimated results of the zeroth path resistance value Rs0, the first path resistance value Rs1, the second path resistance value Rs2, and the third path resistance value Rs3, thereby accurately detecting the first cell voltage Vo(1), the second cell voltage Vo(2), and the third cell voltage Vo(3) even when the zeroth path resistance value Rs0, the first path resistance value Rs1, the second path resistance value Rs2, and the third path resistance value Rs3 are large.

[0042] Next, the operation of the voltage detecting device A according to this embodiment will be described in detail with reference to the flowchart shown in FIG.

[0043] FIG. 3 is a waveform diagram showing the time changes of the first terminal voltage VH1 (negative terminal voltage) and the second terminal voltage VH2 (positive terminal voltage) when the second battery cell b2 (Cell2, even cell) is forcibly discharged (equalized discharged) by the second discharge circuit (even discharge circuit).

[0044] That is, the second discharge switch SW2 changes from the OFF state (open state) to the ON state (closed state) at times t0, t1, t2, t3, t4, ..., and changes from the ON state (closed state) to the OFF state (open state) at times t1', t2', t3', t4', ....

[0045] Among these times t0, t1, t2, t3, t4, ... and times t1', t2', t3', t4', ..., one of the times t0, t1, t2, t3, t4, ... is when the discharge of the second battery cell b2 (Cell2, even cell) is ON. The other times t1', t2', t3', t4', ... is when the discharge of the second battery cell b2 (Cell2, even cell) is OFF.

[0046] Due to this repeated ON / OFF change of the second discharge switch SW2, and due to the first path resistance value Rs1, the second path resistance value Rs2, and the parasitic capacitance (electrostatic capacitance), the first terminal voltage VH1 gradually rises while fluctuating up and down, and the second terminal voltage VH2 gradually drops while fluctuating up and down in the opposite direction to the first terminal voltage VH1.

[0047] The voltage displacement of the first terminal voltage VH1 with respect to the negative electrode voltage of the second battery cell b2 increases as the first path resistance value Rs1 increases, as shown in Fig. 3. Also, the voltage displacement of the second terminal voltage VH2 with respect to the positive electrode voltage of the second battery cell b2 increases as the second path resistance value Rs2 increases, as shown in Fig. 3.

[0048] When the vehicle ignition switch (IG) is first turned from OFF to ON, the voltage detection circuit C sequentially samples the first terminal voltage VH1 and the second terminal voltage VH2 during this equalization discharge to obtain time-series voltage data (step S1). This time-series voltage data is used to correct the first to third reference cell voltages V2(1) to V2(3).

[0049] The voltage detection circuit C acquires not only voltage data such as the first terminal voltage VH1 and the second terminal voltage VH2 during equalization discharge, but also temperature data Tb indicating the temperature of the battery pack B. This temperature data Tb is used to perform temperature correction on the first cell voltage Vo(1), the second cell voltage Vo(2), and the three-cell voltage Vo(3).

[0050] That is, as shown in FIG. 3, the voltage detection circuit C samples the first terminal voltage VH1 and the second terminal voltage VH2 during equalization discharge at times t0, t1', t1, t2', t2, t3', t3, t4', t4, ..., to obtain time-series voltage data V1(t0), V1(t1'), V1(t1), V1(t2'), V1(t2), V1(t3'), V1(t3), V1(t4'), V1(t4), ..., V2(t0), V2(t1'), V2(t1), V2(t2'), V2(t2), V2(t3'), V2(t3), V2(t4'), V2(t4), ....

[0051] On the other hand, the time-series voltage data V1(t0), V1(t1'), V1(t1), V1(t2'), V1(t2), V1(t3'), V1(t3), V1(t4'), V1(t4), ... are obtained by sampling the first terminal voltage VH1 at times t0, t1', t1, t2', t2, t3', t3, t4', t4, ...

[0052] The other time-series voltage data V2(t0), V2(t1'), V2(t1), V2(t2'), V2(t2), V2(t3'), V2(t3), V2(t4'), V2(t4), ... is obtained by sampling the second terminal voltage VH2 at times t0, t1', t1, t2', t2, t3', t3, t4', t4, ...

[0053] Then, the voltage detection circuit C estimates a first voltage correction amount ΔV1(t) for the first terminal voltage VH1 and a second voltage correction amount ΔV2(t) for the second terminal voltage VH2 based on such time-series voltage data V1(t0), V1(t1'), V1(t1), V1(t2'), V1(t2), V1(t3'), V1(t3), V1(t4'), V1(t4), ..., V2(t0), V2(t1'), V2(t1), V2(t2'), V2(t2), V2(t3'), V2(t3), V2(t4'), V2(t4), ... (step S2).

[0054] For example, the first voltage correction amount ΔV1(t1) at time t1 is given by the following equation (1) using the first voltage correction amount ΔV1(t1') at time t1' and the amount ΔV1'(t1) obtained by multiplying the drop voltage Vd of the first voltage correction amount ΔV1(t1) with respect to the negative electrode voltage of the second battery cell b2 by the discharge saturation rate Wd. ΔV1(t1)=ΔV1'(t1)-{V1(t1')-V1(t1)} (1)

[0055] Furthermore, the voltage data V1(t1') at time t1' and the voltage data V1(t1) at time t1 have the relationship shown in the following equation (2) using the discharge saturation rate Wc. V1(t1')-V1(t1)=ΔV1'(t1)×Wc (2)

[0056] On the other hand, the second voltage correction amount ΔV2(t1) at time t1 is given by the following equation (3) using the second voltage correction amount ΔV2(t1') at time t1' and the amount ΔV2'(t1) obtained by multiplying the drop voltage Vd of the second voltage correction amount ΔV2(t1) with respect to the negative electrode voltage of the second battery cell b2 by the discharge saturation rate Wd. ΔV2(t1)=ΔV2'(t1)-{V2(t1')-V2(t1)} (3)

[0057] Furthermore, the voltage data V2(t1') at time t1' and the voltage data V2(t1) at time t1 have the relationship shown in the following equation (4) using the discharge saturation rate Wc. V2(t1')-V2(t1)=ΔV2'(t1)×Wc (4)

[0058] The voltage drop ΔVdis due to the first path resistance value Rs1 and the second path resistance value Rs2 during equalization discharge is expressed as the sum of the first voltage correction amount ΔV1(t1) and the second voltage correction amount ΔV2(t1), as shown in the following equation (5). ΔVdis=ΔV1(t1)+ΔV2(t1) (5)

[0059] As shown in FIG. 4, this voltage drop amount ΔVdis is proportional to the time-series voltage data V1(t0), V1(t1), V1(t2), V1(t3), V1(t4), ..., V2(t0), V2(t1), V2(t2), V2(t3), V2(t4), ... at the times when the second discharge switch SW2 is turned on, that is, times t0, t1, t2, t3, t4, ....

[0060] That is, the absolute value of the voltage drop ΔVdis changes depending on the magnitude of the time-series voltage data V1(t0), V1(t1), V1(t2), V1(t3), V1(t4), ..., V2(t0), V2(t1), V2(t2), V2(t3), V2(t4), ... at the times (t0, t1, t2, t3, t4, ...) when the second discharge switch SW2 is turned on.

[0061] After calculating the voltage drop amount ΔVdis, the voltage detection circuit C uses a pre-stored proportionality coefficient a to estimate the absolute value of the voltage drop amount ΔVdis corresponding to the time-series voltage data V1(t0), V1(t1), V1(t2), V1(t3), V1(t4), ..., V2(t0), V2(t1), V2(t2), V2(t3), V2(t4), ... at the times when the second discharge switch SW2 is turned on (t0, t1, t2, t3, t4, ...) as the second voltage correction amount ΔVh(2) for the second reference cell voltage V2(2).

[0062] Here, the proportionality coefficient a has temperature dependency. That is, the first path resistance value Rs1 and the second path resistance value Rs2 are amounts that fluctuate depending on the temperatures of the first voltage detection line L1 and the second voltage detection line L2, as shown in Fig. 5. The voltage detection circuit C performs temperature correction from the proportionality coefficient a to a proportionality coefficient a' depending on the temperatures of the first voltage detection line L1 and the second voltage detection line L2, as shown in Fig. 6.

[0063] That is, the voltage detection circuit C acquires temperature data Tb input from the battery pack B as the temperatures of the first voltage detection line L1 and the second voltage detection line L2, and uses this temperature data Tb to temperature-correct the proportional coefficient a to a proportional coefficient a'. Then, the voltage detection circuit C estimates a second voltage correction amount ΔVh(2) for the second reference cell voltage V2(2) based on the temperature-corrected proportional coefficient a' and the voltage drop amount ΔVdis.

[0064] The voltage detection circuit C estimates the first voltage correction amount ΔVh(1) and the third voltage correction amount ΔVh(3) for the first reference cell voltage V2(1) and the third reference cell voltage V2(3) in the same manner as the second voltage correction amount ΔVh(2) described above by controlling the ON / OFF of the first discharge switch SW1 and the third discharge switch SW3.

[0065] Then, the voltage detection circuit C corrects the first reference cell voltage V2(1), the second reference cell voltage V2(2), and the third reference cell voltage V2(3) based on the first voltage correction amount ΔVh(1), the second voltage correction amount ΔVh(2), and the third voltage correction amount ΔVh(3) estimated in this manner (step S3).

[0066] That is, the voltage detection circuit C completes the voltage correction by adding the first voltage correction amount ΔVh(1), the second voltage correction amount ΔVh(2), and the third voltage correction amount ΔVh(3) to the first reference cell voltage V2(1), the second reference cell voltage V2(2), and the third reference cell voltage V2(3), respectively.

[0067] The first corrected cell voltage V2h(1), the second corrected cell voltage V2h(2), and the third corrected cell voltage V2h(3) obtained by such voltage correction are very close to the first cell voltage Vo(1), the second cell voltage Vo(2), and the third cell voltage Vo(3).

[0068] The voltage detection device A of this embodiment includes a plurality of discharge circuits that are connected in parallel to the plurality of battery cells b1 to b3 via predetermined voltage detection lines L0 to L3, respectively, and that equalize and discharge the battery cells b1 to b3, and a voltage detection circuit C that detects the cell voltages of the battery cells b1 to b3 based on the negative terminal voltage and the positive terminal voltage that are input to the plurality of input terminals T0 to T3 via the voltage detection lines L0 to L3, respectively.

[0069] Furthermore, in the voltage detection device A according to this embodiment, the voltage detection circuit C acquires the negative terminal voltage and the positive terminal voltage during equalization discharge by the multiple discharge circuits, estimates the voltage drop ΔVdis due to the voltage detection lines L0 to L3 based on the negative terminal voltage and the positive terminal voltage, and detects the cell voltage by correcting the negative terminal voltage and the positive terminal voltage based on the voltage drop ΔVdis.

[0070] According to this embodiment, the negative terminal voltage and the positive terminal voltage are corrected based on the negative terminal voltage and the positive terminal voltage during equalization discharge, so that a voltage detection device A can be provided that can detect cell voltages more accurately than conventional devices even when the path resistance values ​​Rs0 to Rs3 of the voltage detection lines L0 to L3 are large.

[0071] Furthermore, in the voltage detection device A of this embodiment, the voltage detection circuit C estimates the voltage drop amount ΔVdis according to the temperature data Tb acquired as the temperature of the voltage detection lines L0 to L3, so that it is possible to detect the cell voltage with high accuracy in response to temperature changes of the voltage detection lines L0 to L3.

[0072] Furthermore, in the voltage detection device A of this embodiment, the voltage detection circuit C acquires the negative terminal voltage and the positive terminal voltage when discharge is ON and when discharge is OFF during equalization discharge, so that the negative terminal voltage and the positive terminal voltage can be accurately corrected.

[0073] Therefore, according to this embodiment, it is possible to detect the cell voltage more accurately than before based on the negative terminal voltage and the positive terminal voltage when discharge is ON and OFF during equalization discharge.

[0074] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. For example, the detection target is not limited to the above-described battery pack B, i.e., a battery pack having three battery cells b1 to b3. The detection target may be, for example, a battery pack (lithium ion battery) with 72 cells or a battery pack (lithium ion battery) with 60 cells. [Explanation of symbols]

[0075] A Voltage detection device B Battery pack b1~b3 battery cells L0~L3 voltage detection lines T0 to T3 input terminals H0~H3 Discharge resistor C Voltage detection circuit SW1~SW3 Discharge switches D1~D3 ON resistor

Claims

1. A voltage detection device comprising: a plurality of discharge circuits each connected in parallel to a plurality of battery cells via predetermined voltage detection lines, and discharging the battery cells equally; and a voltage detection circuit that detects the cell voltages of the battery cells based on a negative terminal voltage and a positive terminal voltage input to a plurality of input terminals via the voltage detection lines, The voltage detection circuit acquires the negative terminal voltage and the positive terminal voltage during equalization discharge, estimates a voltage drop amount due to the voltage detection line based on the negative terminal voltage and the positive terminal voltage, and detects the cell voltage by correcting the negative terminal voltage and the positive terminal voltage based on the voltage drop amount. A voltage detection device characterized by:

2. 2. The voltage detection device according to claim 1, wherein the voltage detection circuit estimates the amount of voltage drop according to the temperature of the voltage detection line.

3. 3. The voltage detection device according to claim 1, wherein the voltage detection circuit acquires the negative terminal voltage and the positive terminal voltage when discharge is on and when discharge is off.

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