JP2016080478A - Voltage detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage detecting device the accuracy of detecting cell discharge voltage of which can be improved.SOLUTION: The voltage detecting device is comprised of a discharge circuit and voltage detection parts D and M. The discharge circuit comprises at least one cell C, a bypass resistor arranged in parallel to at least one cell, a connection electrically connecting both ends of at least one cell to the bypass resistor and a switching element SW that permits the bypass resistor to discharge at least one cell. The voltage detection part D can detect the end-to-end voltage of the bypass resistor as the detected voltage. When the discharge circuit discharges at least one cell, the voltage detection part M corrects the detected voltage Vad with a correction coefficient α obtained from the interior resistance value Ra of at least one cell, the wiring resistance values Rb1, Rb2, Rc1 and Rc2 and the bypass resistance value Rdis of the bypass resistor to determine the discharge voltage of at least one cell.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a device for detecting a voltage (voltage detection device).

  For example, Patent Document 1 discloses a battery system, and the battery system includes a battery having a plurality of batteries (cells) and a voltage detection circuit (cell voltage detection) capable of detecting each of a plurality of voltages corresponding to the plurality of batteries. Part) and a plurality of discharge resistors (bypass resistors that can pass the current and consume battery power) that can equalize a plurality of voltages (cell voltages). Further, the battery system compares a difference between a non-discharge voltage (cell voltage in a non-discharge state) and a discharge voltage (cell voltage in a discharge state) of a certain battery among a plurality of batteries and a normal voltage (threshold value). Alternatively, the discharge voltage of a certain battery can be compared with a normal voltage (threshold) to determine whether or not there is an abnormality in the connection between the certain battery and the voltage detection circuit.

JP 2010-127722 A

  However, the present inventors have recognized that the detection accuracy of the discharge voltage of the battery by the battery system or the voltage detection circuit of Patent Document 1 is reduced. That is, when the discharge resistor discharges the battery, the detection voltage detected by the voltage detection circuit (the voltage across the discharge resistor input to the voltage detection circuit) is higher than the discharge voltage of the battery. It becomes small by the resistance value of the discharge circuit (closed circuit). In other words, the discharge voltage of the battery does not match the detection voltage detected by the voltage detection circuit by the amount of voltage drop. Nevertheless, not only the battery system or the voltage detection circuit of Patent Document 1, but also the conventional voltage detection device is based on the premise that the detection voltage matches the discharge voltage of the battery.

  One object of the present invention is to provide a voltage detection device capable of improving the detection accuracy of a discharge voltage (a cell voltage in a discharged state) of a battery. Other objects of the present invention will become apparent to those skilled in the art by referring to the aspects and best embodiments exemplified below and the accompanying drawings.

  In the following, in order to easily understand the outline of the present invention, embodiments according to the present invention will be exemplified.

In the first aspect, the voltage detection device electrically connects at least one battery, a bypass resistor arranged in parallel to the at least one battery, both ends of the at least one battery, and the bypass resistor. A discharge circuit composed of a connection unit to be connected; a switching element that allows the bypass resistor to discharge the at least one battery; and a voltage detection unit capable of detecting a voltage across the bypass resistor as a detection voltage And comprising
When the discharge circuit discharges the at least one battery, the voltage detection unit converts the detection voltage into an internal resistance value of the at least one battery, a wiring resistance value of the connection unit, and a bypass resistance of the bypass resistor. The discharge voltage of the at least one battery is determined by correcting with a correction coefficient obtained from the value.

  In the first aspect, it is not premised that the voltage detected by the voltage detector matches the battery discharge voltage. Therefore, the voltage detector corrects the detected voltage with the correction coefficient to determine the battery discharge voltage. Here, the correction coefficient is obtained from the internal resistance value of the battery, the wiring resistance value of the connection portion, and the bypass resistance value of the bypass resistor. Thereby, the voltage detection apparatus can improve the detection accuracy of the battery discharge voltage (discharged cell voltage) in the voltage detection unit.

In a second aspect subordinate to the first aspect, the voltage detection unit may determine the discharge voltage by correcting the detection voltage using the following relational expression.
Vcell = Vad (Rdis + RL) / Rdis
Here, Vcell, Vad, and Rdis may be the discharge voltage, the detection voltage, and the bypass resistance value, respectively, and RL may include a combined resistance value of the internal resistance value and the wiring resistance value. Good.

  In the second aspect, the correction coefficient can be set to (Rdis + RL) / Rdis. Therefore, the voltage detection unit can correct the detection voltage in consideration of the voltage drop. Thereby, the voltage detection apparatus can further improve the detection accuracy of the discharge voltage of the battery in the voltage detection unit.

In a third aspect subordinate to the first or second aspect, the voltage detection device may further include a temperature sensor that measures a temperature of the at least one battery,
Each of the internal resistance value and the wiring resistance value may depend on the temperature.

  In the third aspect, the internal resistance value and the wiring resistance value included in the correction coefficient can be changed by the battery temperature. Therefore, the voltage detection unit can correct the detection voltage in consideration of the battery temperature. Thereby, the voltage detection apparatus can further improve the detection accuracy of the discharge voltage of the battery in the voltage detection unit.

  Those skilled in the art will readily understand that the illustrated embodiments according to the present invention can be further modified without departing from the spirit of the present invention.

The structural example of the voltage detection apparatus according to this invention is shown. An explanatory view of a voltage drop (a difference between a discharge voltage and a detection voltage) when a current flows through the discharge circuit of FIG. 1 is shown. The flowchart which shows the operation example of the voltage detection apparatus of FIG. 1 is shown. 4A and 4B are graphs showing the temperature dependence of the internal resistance value of the battery of FIG. 2 and the wiring resistance value of the harness, respectively.

  The best mode described below is used to easily understand the present invention. Accordingly, those skilled in the art should note that the present invention is not unduly limited by the embodiments described below.

  FIG. 1 shows a configuration example of a voltage detection device according to the present invention, and the voltage detection device can include, for example, a discharge circuit and a voltage detection unit. In FIG. 1, for example, one discharge circuit of the voltage detection device includes, for example, one battery C11, a bypass resistor (having a bypass resistance value Rdis11) arranged in parallel to the battery C11, both ends of the battery C11, and a bypass resistor. And a switching element SW11 that allows the bypass resistor to discharge the battery C11. The connecting portion (including the harnesses H11 and H12) electrically connects the device (Rdis11). FIG. 1 shows a detection circuit S1, for example, and a part of the discharge circuit, that is, a bypass resistor and a switching element SW11 are arranged in the detection circuit S1.

  The detection circuit S1 may further include at least one cell voltage detection unit (for example, the cell voltage detection unit D in FIG. 2). When the discharge circuit discharges the battery C11, in other words, when the switching element SW11 is turned on, the detection circuit S1 of FIG. 1 can detect the voltage across the bypass resistor as the detection voltage. In FIG. 1, the detection circuit S1 can send the detection voltage to, for example, the processing unit M, and the processing unit M corrects the detection voltage to determine or calculate the discharge voltage (cell voltage in the discharge state) of the battery C11. be able to. A part of the voltage detection unit, that is, the cell voltage detection unit D can be arranged in the detection circuit S1. In other words, for example, the cell voltage detection unit D and the processing unit M can constitute a voltage detection unit of the voltage detection device.

  In FIG. 1, for example, the detection circuit S1 can detect, for example, n discharge voltages of, for example, n batteries C11, C12,..., C1n constituting one battery module. In other words, the detection circuit S1, for example, corresponds to n discharge circuits, for example, n bypass resistors (bypass resistance values Rdis11, Rdis12,..., Rdis1n) and, for example, n switching elements SW11, SW1 ..., SW1n. The detection circuit S1 of FIG. 1 is included in a control unit 10 mounted on a vehicle (not shown) such as an automobile.

  The control unit 10 of FIG. 1 includes, for example, M detection circuits S1, S2,..., SM in order to correspond to, for example, M battery modules. In FIG. 1, each of the M battery modules is composed of, for example, n batteries, and therefore each of the M detection circuits S1, S2,..., SM can detect n discharge voltages. It is. The M detection circuits S1, S2,..., SM in FIG. 1 are connected, for example, in a daisy chain type, and can communicate with the processing unit 31 through, for example, the insulating elements FC1, FC2. The insulating elements FC1, FC2 electrically insulate between the M detection circuits S1, S2,..., SM and the processing unit 31, and thus can be driven at, for example, 12 [V]. The ground (not shown) in the high voltage region including the detection circuits S1, S2,..., SM (and M battery modules) includes a processing unit M that can be driven at, for example, 5 [V]. It is not connected to the ground of the area (not shown), that is, for example, the vehicle body ground (not shown), and is floating. The insulating elements FC1 and FC2 are, for example, photocouplers.

  Of course, each of the M detection circuits S1, S2,..., SM in FIG. 1 may be connected to the processing unit M by, for example, a star type, a hub type, or a tree type. 1 may be included in the high voltage region. In other words, the function (determining or calculating the discharge voltage) of the processing unit M in FIG. 1 may be executed or realized by each of the M detection circuits S1, S2,.

  In FIG. 1, the number “M” of battery modules is arbitrary. The number “n” of batteries or discharge circuits in one battery module is also arbitrary. Preferably, each of M and N is plural, and more preferably, M and N necessary for constructing a vehicle driving power source of, for example, several hundred [V] are selected or selected. M is typically 12 or 6, for example. The vehicle drive power supply is typically a power supply of a motor MT that constitutes a drive unit of an electric vehicle or a hybrid vehicle, for example. The M battery modules are connected in series to constitute one battery (vehicle driving battery), and both ends (vehicle driving power supply) of the battery (M battery modules) are, for example, mechanical switches CT1. , CT2 is connected to the motor drive circuit INV, whereby the vehicle drive power is supplied to the motor MT via the motor drive circuit INV. Here, the switches CT1 and CT2 are, for example, contactors, and the motor drive circuit INV is, for example, a three-phase inverter.

  The processing unit M is configured by a microcomputer, for example, and can include, for example, a CPU, a ROM, a RAM, an input / output interface, and the like. For example, the ROM can store a program that causes the CPU to execute a predetermined operation, and the RAM can form a work area of the CPU. Further, the processing unit M or, for example, the ROM can store data necessary for correcting the detection voltage from the detection circuit S1, for example, correction coefficients. Preferably, the processing unit M includes a plurality of voltages corresponding to a plurality of batteries C11, C12,..., C1n, C21, C22,. .., SM is managed or controlled to equalize a plurality of voltages or a plurality of batteries C11, C12,..., C1n, C21, C22,. .., C2n,..., CM1, CM2,..., CMn can be discharged (cell balance control). More preferably, the processing unit M can manage or control charging / discharging of the battery (M battery modules) according to, for example, the traveling state of the vehicle. The batteries C11, C12,..., C1n are rechargeable storage batteries (secondary batteries) such as lithium ion batteries and hydrogen nickel batteries.

  In FIG. 1, M temperature sensors T1, T2,..., TM, for example, are arranged in M battery modules. Accordingly, the processing unit M can correct the detection voltage in consideration of the temperature of the battery that has passed through the M detection circuits S1, S2,..., SM, for example. The number “M” of the temperature sensors T1, T2,..., TM is arbitrary. For example, one temperature sensor may be shared by a plurality of battery modules. Alternatively, one temperature sensor may be set for all of the M battery modules. Alternatively, all of the temperature sensors T1, T2,..., TM may be omitted.

  FIG. 2 is an explanatory diagram of a voltage drop (a difference between the discharge voltage and the detection voltage) when a current flows through the discharge circuit of FIG. The battery C in FIG. 2 corresponds to, for example, the battery C11 in FIG. 1, and the bypass resistor (having the bypass resistance value Rdis) in FIG. 2 is, for example, a bypass resistor (bypass) arranged in parallel with the battery C11 in FIG. 2 has a resistance value Rdis11), and the switching element SW in FIG. 2 corresponds to, for example, the switching element SW11 in FIG. The detection circuit S in FIG. 2 corresponds to a part of the detection circuit S1 in FIG. In other words, the detection circuit S1 in FIG. 1 includes not only the bypass resistor and the switching element SW in FIG. 2 but also (n−1) bypass resistors and (n−1) switching elements not shown in FIG. Can be included. In addition, the detection circuit S1 of FIG. 1 can include not only the cell voltage detection unit D of FIG. 2 but also (n−1) cell voltage detection units not shown in FIG. Here, the detection circuit S1 of FIG. 1 may include only one cell voltage detection unit D. In other words, the cell voltage detection unit D of FIG. Like the A / D converter, for example, it may be shared by n discharge circuits of FIG.

  Incidentally, in order for the processing unit M in FIG. 1 to execute, for example, cell balance control, the control unit 10 in FIG. 1 or the M detection circuits S1, S2,..., SM has, for example, (M × n) pieces. A cell voltage detector D (see FIG. 2) can be included. However, when the processing unit M does not execute cell balance control, for example, the control unit 10 of FIG. 1 or each of the M detection circuits S1, S2,..., SM has at least one discharge circuit (FIG. 2). Reference) may be included. Specifically, the battery C of FIG. 2 is, for example, the battery of FIG. 1 (M battery modules) or, for example, one battery module of FIG. 1 (for example, n batteries C11, C12,..., C1n The control unit 10 of FIG. 2 may have only one discharge circuit (see FIG. 2).

  When the battery C in FIG. 2 corresponds to the battery C11 in FIG. 1, for example, the harness H in FIG. 2 corresponds to, for example, the harness H11 and the harness H12 in FIG. Alternatively, when the battery C in FIG. 2 corresponds to, for example, one battery module in FIG. 1 (for example, n batteries C11, C12,..., C1n), the harness H in FIG. You may respond | correspond to harness H11 and harness H1 (n + 1).

  The battery C in FIG. 2 is represented by a cell voltage Vcell and an internal resistor (having an internal resistance value Ra). The harness H in FIG. 2 is represented by upper and lower or two wiring resistors (having a wiring resistance value Rb1 and a wiring resistance value Rb2) in order to connect both ends of the battery C and the connector CNT of the control unit 10. . The connector CNT of FIG. 2 is provided, for example, in the housing of the control unit 10 (see the dotted line in FIG. 2), and the connector CNT is represented by two contact resistors (having a contact resistance value Rc1 and a contact resistance value Rc2). Has been. The voltage across the battery C, that is, the cell voltage Vcell, is an internal resistor (internal resistance value Ra) of the battery C, a wiring resistor (wiring resistance values Rb1, Rb2) of the harness H, and a contact resistor (contact resistance value) of the connector CNT It is input to the control unit 10 via Rc1, Rc2).

  In FIG. 2, the connector CNT is electrically connected to the bypass resistor and the switching element SW. The bypass resistor, the switching element SW, and the cell voltage detector D are typically fixed to a substrate (high voltage substrate) (not shown), and the line (wiring in the control unit 10) in FIG. It is. Therefore, the connection part that electrically connects both ends of the battery C and both ends of the bypass resistor (Rdis) includes, for example, a harness H, a connector CNT, and wiring (for example, printed wiring in the control unit 10).

  Strictly speaking, the connection portion electrically connects both ends of the battery C in FIG. 2 and both ends of the bypass resistor and the switching element SW (two nodes detected or input by the cell voltage detection portion D). doing. Accordingly, the cell voltage detector D in FIG. 2 detects or inputs the voltage across the bypass resistor and the switching element SW. However, the cell voltage detection unit D may detect or input only the voltage across the bypass resistor, and the connection unit may further include a switching element SW.

  When the switching element SW is turned on by, for example, the cell voltage detector D to form the discharge circuit (closed circuit) of FIG. 2, the discharge current I flows through the discharge circuit. Therefore, the discharge voltage Vcell of the battery C does not coincide with the detection voltage Vad detected by the cell voltage detection unit D by the amount of voltage drop. Specifically, when the switching element SW arranged in parallel with the bypass resistor in the battery C permits the discharge of the battery C, the discharge current I and the discharge voltage Vcell are respectively expressed by the following formula (1): And Formula (2).

I = (Vcell−Vad) / RL (1)
Vcell = I × (Rdis + RL) (2)
Here, RL is a resistance value of a discharge circuit (closed circuit) other than the bypass resistor (discharge resistor), and RL can be expressed by the following equation (3), for example.

RL = Ra + Rb1 + Rb2 + Rc1 + Rc2 (3)
In Expression (3), RL is the wiring resistance value of the control unit 10, that is, for example, the connector CNT, the bypass resistor, and both ends of the switching element SW (two nodes detected or input by the cell voltage detection unit D). The wiring resistance value between is not included. Further, RL does not include the ON resistance value of the switching element SW. The reason is that the wiring resistance value of the control unit 10 and the ON resistance value of the switching element SW are much smaller than the bypass resistance value Rdis of the bypass resistor, for example, and thus those skilled in the art generally ignore these resistance values. Because it can be done.

  RL in Expression (3) is a combined resistance value of the internal resistance value Ra of the battery C, the wiring resistance values Rb1 and Rb2 of the harness, and the contact resistance values Rc1 and Rc2 of the connector CNT. However, when the contact resistance values Rc1 and Rc2 are small, those skilled in the art may ignore the contact resistance values Rc1 and Rc2. In other words, RL may be a combined resistance value of the internal resistance value Ra of the battery C and the wiring resistance values Rb1 and Rb2 of the harness.

By substituting equation (1) into equation (2), the discharge voltage Vcell can be expressed by the following equations (4) and (5).
Vcell = (Vcell−Vad) × (Rdis + RL) / RL (4)
Vcell = Vad (Rdis + RL) / Rdis (5)
Equation (5) is equivalent to Equation (4).

  When (Rdis + RL) / Rdis in equation (5) is used as the correction coefficient α, the detection voltage Vad can be corrected with the correction coefficient α to determine or calculate an accurate discharge voltage Vcell. The correction coefficient α is not limited to the equation (5), and the correction coefficient is obtained from the internal resistance value Ra of the battery C, the wiring resistance values Rb1 and Rb2 of the connection part or harness, and the bypass resistance value Rdis of the bypass resistor. It only has to be. In other words, those skilled in the art may ignore the contact resistance values Rc1 and Rc2 of the connector CNT.

  2 sends the detection voltage Vad to the processing unit M in FIG. 1, and the processing unit M converts the detection voltage Vad into a correction coefficient or, for example, an equation ( 5), the discharge voltage Vcell of FIG. 2 (or the plurality of batteries C11, C12,..., C1n, C21, C22,..., C2n,..., CM1, CM2,. .., Each of a plurality of voltages corresponding to CMn) can be determined or calculated. Of course, the detection voltage Vad is corrected only by the cell voltage detector D in FIG. 2 (or the detection circuit S1 in FIG. 1, for example) with a correction coefficient or, for example, the equation (5), and the discharge voltage Vcell in FIG. For example, the voltage corresponding to the battery C11) may be determined or calculated. In other words, the cell voltage detection unit D may include, for example, a flying capacitor type voltage detection unit, a correction or calculation unit such as a microcomputer, and a logic circuit processing unit.

  Preferably, the cell voltage detector D in FIG. 2 (or the detection circuit S1 in FIG. 1, for example) is the battery C (or the battery C11 in FIG. 1, for example) measured by the temperature sensor T (or the temperature sensor T1 in FIG. 1). ) Can be sent to the processing unit M in FIG. The processing unit M in FIG. 1 can correct the detection voltage Vad in consideration of the temperature of the battery C in FIG. In FIG. 2, the temperature sensor T is connected to the cell voltage detector D, but the temperature sensor T (or M temperature sensors T1, T2,..., TM in FIG. 1, for example) The processing unit M may be directly connected.

  FIG. 3 is a flowchart showing an operation example of the voltage detection apparatus of FIG. The voltage detection unit of the voltage detection device, specifically, for example, the processing unit M in FIG. 1 can manage or control charging / discharging of the battery (M battery modules). For example, when batteries (M battery modules) are charged, for example, (M × n) batteries C11, C12,..., C1n, C21, C22,. Assume that one of CM2,..., CMn is fully charged. In other words, each of the plurality of batteries has an individual difference, and the plurality of voltages corresponding to the plurality of batteries do not necessarily indicate the same value.

  When at least one of the plurality of batteries is fully charged, it is preferable to stop or interrupt charging of other batteries that are not fully charged. The reason is that if the battery that is fully charged continues to be charged, the battery may be deteriorated. Accordingly, it is preferable to discharge a battery that is fully charged and continue charging other batteries that are not fully charged. Accordingly, the processing unit M in FIG. 1 includes, for example, (M × n) batteries C11, C12,..., C1n, C21, C22,. , CMn can be transmitted to each of the M detection circuits S1, S2,..., SM to manage or control (M × n) voltages corresponding to CMn (FIG. 3). (See step ST1).

  Specifically, the processing unit M in FIG. 1 determines that the battery C11 in FIG. 1 needs to be discharged, for example, and the processing unit M can transmit a discharge instruction to the detection circuit S1, for example. In response to receiving the discharge instruction, the detection circuit S1 of FIG. 1 (or the cell voltage detection unit D of FIG. 2, for example) turns on the switching element SW11, and a discharge current starts to flow through the discharge circuit including the battery C11. In response to the discharge instruction, the detection circuit S1 of FIG. 1 can detect the temperature of the battery C11, for example, via the temperature sensor T1, for example (see step ST2 of FIG. 3).

  Specifically, for example, the detection circuit S1 can transmit the temperature of the battery C11 to the processing unit M, for example. In response to receiving the temperature of the battery C11, the processing unit M can determine the internal resistance value of the internal resistor of the battery C11 and the wiring resistance values of the harnesses H11 and H12. When each of the internal resistance value and the wiring resistance value depends on the temperature, the processing unit M can determine the internal resistance value and the wiring resistance value using, for example, a temperature dependence map. The processing unit M or the ROM, for example, can store such a map, and the processing unit M can refer to or obtain the internal resistance value and the wiring resistance value corresponding to the temperature of the battery C11.

  For example, after the detection circuit S1 turns on the switching element SW11, for example, the detection circuit S1 (or, for example, the cell voltage detection unit D in FIG. 2) sets the detection voltage (Vad) corresponding to the voltage of the battery C11 (discharge voltage Vcell). It can be detected (see step ST3 in FIG. 3). Specifically, the detection circuit S1 can detect a voltage across the bypass resistor (for example, having a bypass resistance value Rdis11) as a detection voltage (Vad), and can transmit the detection voltage to the processing unit M, for example. Strictly speaking, the detection circuit S1 (or, for example, the cell voltage detection unit D in FIG. 2) has a voltage across the bypass resistor and the switching element SW11 (between two nodes detected or input by the cell voltage detection unit D). Voltage) can be detected.

  In response to reception of the detection voltage (Vad), the processing unit M can perform correction value calculation (see step ST4 in FIG. 3). Specifically, the processing unit M can calculate the correction coefficient α, for example, (Rdis + RL) / Rdis in Expression (5). For example, according to the formula (3), RL = Ra + Rb1 + Rb2 + Rc1 + Rc2 is established, so that the processing unit M can change only Ra, Rb1, and Rb2, for example, according to the temperature of the battery C11 (see step ST2 in FIG. 3). . Next, the processing unit M can multiply the detection voltage (Vad) by the correction coefficient α.

  The processing unit M can determine the multiplication result of the detection voltage (Vad) and the correction coefficient α, for example, Vcell in Expression (5) as the voltage of the battery C11 (see step ST5 in FIG. 3). For example, when discharging the battery C11 of FIG. 1, the processing unit M can determine the discharge voltage of the battery C11 in such a procedure. Similarly, the processing unit M includes other batteries (for example, the batteries C12,..., C1n, C21, C22,..., C2n,..., CM1, CM2,. The discharge voltage can be determined. In this way, the processing unit M can manage or control charging of the battery (M battery modules).

  4A and 4B are graphs showing the temperature dependence of the internal resistance value of the battery of FIG. 2 and the wiring resistance value of the harness, respectively. As shown in FIG. 4A, the internal resistance value Ra of the battery C in FIG. 2 decreases as the temperature increases. Further, as shown in FIG. 4B, the wiring resistance value Rb (Rb1 + Rb2) of the harness in FIG. 2 increases as the temperature increases. Thus, the internal resistance value Ra and the wiring resistance value Rb depend on the temperature measured by the temperature sensor T. The present inventors have recognized that the detection accuracy of the discharge voltage Vcell of the battery C is improved by considering the temperature dependence of the resistance values Ra and Rb. Each of the relational expressions shown in FIGS. 4A and 4B is only an example. For example, as the temperature increases depending on the harness material, the wiring resistance of the harness shown in FIG. The value Rb (Rb1 + Rb2) may decrease.

  Strictly speaking, the contact resistance values Rc1 and Rc2 of the connector CNT in FIG. 2 also have temperature dependence. Further, the bypass resistance value Rdis of the bypass resistor also has temperature dependence. Since the contact resistance values Rc1 and Rc2 are smaller than the internal resistance value Ra and the wiring resistance value Rb (Rb1 + Rb2), the present inventors do not need to consider the temperature dependence of the contact resistance values Rc1 and Rc2, and thus the battery C It was recognized that the detection accuracy of the discharge voltage Vcell was not lowered. In other words, the temperature dependence of the resistance values Ra and Rb is stored in the processing unit M or ROM of FIG. 1, for example, as a function, table, or the like representing the relational expressions shown in FIGS. 4 (A) and 4 (B). By not storing the temperature dependence of the contact resistance values Rc1 and Rc2, it is possible to suppress an increase in the storage capacity of the processing unit M or ROM.

Further, the temperature dependence of the bypass resistance value Rdis (and ON resistance value) is reflected in the detection voltage Vad. In other words, the expression (5) can be modified as the following expression (6), and the detection voltage Vad hardly changes when the bypass resistance value Rdis changes. That is, the detection voltage Vad can cancel the temperature dependence of the bypass resistance value Rdis.
Vad = Vcell · Rdis / (Rdis + RL) (6)
The present inventors have recognized that the detection accuracy of the discharge voltage Vcell of the battery C does not decrease without considering the temperature dependence of the bypass resistance value Rdis.

  Each of the relational expressions (temperature dependence of the internal resistance value of the battery and the wiring resistance value of the harness) shown in FIGS. 4A and 4B is, for example, (M × n) batteries C11 in FIG. , C12, ..., C1n, C21, C22, ..., C2n, ..., CM1, CM2, ..., CMn may be common or shared relational expressions. Since one temperature dependency of the internal resistance value and one wiring resistance value of the harness are stored in the processing unit M or ROM of FIG. 1, an increase in the storage capacity of the processing unit M or ROM can be suppressed.

  However, the relational expressions shown in FIGS. 4A and 4B are, for example, (M × n) batteries C11, C12,..., C1n, C21, C22,. .., C2n,..., CM1, CM2,. In other words, for example, the temperature dependency (internal resistance value) of the battery C11 is different from, for example, the temperature dependency of the battery C12, and the temperature dependency (wiring resistance value) of the harness H11 in FIG. 1 is, for example, that of the harness H12 or the harness H13. May differ from temperature dependence. Since the individual temperature dependence of the internal resistance value and the individual wiring resistance value of the harness are stored in the processing unit M or ROM of FIG. 1, the detection accuracy of the discharge voltage of each battery can be further improved.

  The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily modify the above-described exemplary embodiments to the extent included in the claims. .

  DESCRIPTION OF SYMBOLS 10 ... Control unit, C ... Battery (cell), CNT ... Connector, CT ... Switch, FC ... Insulating element, H ... Harness, INV ... Motor drive circuit, M ... Processing unit, MT ... Motor, Rdis ... Bypass resistance, S ... Detection circuit, SW ... Switching element, T ... Temperature sensor.

Claims (3)

At least one battery, a bypass resistor arranged in parallel with the at least one battery, a connection part that electrically connects both ends of the at least one battery and the bypass resistor, and the bypass resistor A voltage detection device comprising: a discharge circuit configured to allow discharge of the at least one battery; and a voltage detection unit capable of detecting a voltage across the bypass resistor as a detection voltage,
When the discharge circuit discharges the at least one battery, the voltage detection unit converts the detection voltage into an internal resistance value of the at least one battery, a wiring resistance value of the connection unit, and a bypass resistance of the bypass resistor. And a correction coefficient determined from the value to determine a discharge voltage of the at least one battery. The voltage detection device according to claim 1, wherein the voltage detection unit corrects the detection voltage using the following relational expression to determine the discharge voltage.
Vcell = Vad (Rdis + RL) / Rdis
Here, Vcell, Vad, and Rdis are the discharge voltage, the detection voltage, and the bypass resistance value, respectively, and RL includes a combined resistance value of the internal resistance value and the wiring resistance value. A temperature sensor for measuring a temperature of the at least one battery;
The voltage detection device according to claim 1, wherein each of the internal resistance value and the wiring resistance value depends on the temperature.

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