JP6848756B2 - Battery pack - Google Patents

Description

The present invention relates to a battery pack.

As an existing battery pack, two current detection units that detect the current flowing through the battery are provided, and the currents detected by each current detection unit are compared with each other to determine whether each current detection unit is normal or abnormal. There is something to do.

Related techniques include, for example, Patent Documents 1 to 4.

Japanese Unexamined Patent Publication No. 2013-242324 Japanese Patent No. 5187234 Japanese Unexamined Patent Publication No. 2016-192894 JP-A-2007-085843

However, as described above, in a battery pack provided with two current detection units, if each current detection unit is composed of relatively expensive parts, there is a concern that the manufacturing cost will increase.
Therefore, an object of one aspect of the present invention is to provide a battery pack capable of suppressing an increase in manufacturing cost in order to determine whether the current detection unit is normal or abnormal.

The battery pack, which is one embodiment of the present invention, includes a battery, a first voltage detection unit that detects the voltage of the battery, a current detection unit that detects the current flowing through the battery, and an abnormality detection unit connected in parallel to the battery. It includes a circuit and a control unit.

The abnormality detection circuit consists of two voltage dividing resistors that divide the voltage of the battery, a second voltage detector that detects the voltage at the connection point of the two voltage dividing resistors, and a relay connected in series to the two voltage dividing resistors. And.

The control unit has an open state battery voltage detected by the first voltage detection unit when the relay is in the open state and an open state detected by the second voltage detection unit when the relay is in the open state. State Judges whether the connection point voltages are the same as each other.

Further, in the control unit, the closed state connection point voltage detected by the second voltage detection unit when the relay is in the closed state is measured by the first voltage detection unit when the relay is in the closed state. Same as the assumed voltage at the connection point of the two divided resistors, which is obtained from the detected closed battery voltage, open battery voltage, or open connection point voltage and the respective resistance values of the two divided resistors. Judge whether or not.

Further, the control unit closes the relay when it determines that the open state battery voltage and the open state connection point voltage are the same as each other and the closed state connection point voltage is the same as the assumed voltage. The amount of change in current between the current detected by the current detector when the state is open and the current detected by the current detector when the relay is open is the closed state battery voltage and the open state battery voltage. Or, if it is the same as the estimated current change amount of the current flowing through the battery, which is obtained from the open state connection point voltage and the resistance value of each of the two voltage dividing resistors, it is determined that the current detector is normal. If the current change amount is not the same as the assumed current change amount, the current detection unit determines that the current is abnormal.

According to the present invention, in the battery pack, it is possible to suppress an increase in manufacturing cost in order to determine whether the current detection unit that detects the current flowing through the battery is normal or abnormal.

It is a figure which shows an example of the battery pack of an embodiment. It is a flowchart which shows an example of the operation of a control part. It is a flowchart which shows another example of operation of a control part. It is a flowchart which shows still another example of the operation of a control part. It is a flowchart which shows still another example of the operation of a control part. It is a flowchart which shows still another example of the operation of a control part.

Hereinafter, embodiments will be described in detail based on the drawings.
FIG. 1 is a diagram showing an example of a battery pack of the embodiment.
The battery pack shown in FIG. 1 has an abnormality in which the battery B, the first voltage detection unit 1 that detects the voltage of the battery B, the current detection unit 3 that detects the current flowing through the battery B, and the battery B are connected in parallel. It includes a detection circuit and a control unit 4.

The abnormality detection circuit includes two voltage dividing resistors R1 and R2 that divide the voltage of the battery B, a second voltage detecting unit 2 that detects the voltage at the connection point P of the two voltage dividing resistors R1 and R2, and the voltage dividing circuit. It includes a relay Re connected in series with resistors R1 and R2.

The battery B is composed of one or more secondary batteries such as a lithium ion battery and a nickel hydrogen battery, and supplies electric power to a load Lo such as an auxiliary machine or an electrical device mounted on a vehicle.
The voltage dividing resistors R1 and R2 are connected in series with each other. That is, one terminal of the voltage dividing resistor R1 is connected to one terminal of the battery B (a positive terminal in the example shown in FIG. 1), and the other terminal of the voltage dividing resistor R1 is connected to one terminal of the voltage dividing resistor R2. Has been done. The other terminal of the voltage dividing resistor R2 is connected to the other terminal of the battery B (minus terminal in the example shown in FIG. 1) via the relay Re and the current detection unit 3. The voltage dividing resistors R1 and R2 may each be composed of two or more resistors.

The relay Re is composed of, for example, an electromagnetic relay. When the relay Re is changed from the open state to the closed state, a current flows from one terminal of the battery B to the other terminal of the battery B via the voltage dividing resistors R1 and R2, the relay Re, and the current detection unit 3. The relay Re may be provided between the connection point P and the voltage dividing resistor R2.

The first voltage detection unit 1 and the second voltage detection unit 2 are composed of, for example, an IC (Integrated Circuit).
The current detection unit 3 is composed of, for example, a shunt resistor. By configuring the current detection unit 3 with inexpensive parts such as a shunt resistor in this way, it is possible to reduce the manufacturing cost of the battery pack as compared with the case where the current detection unit 3 is composed of expensive parts. Further, for example, the resistance values of the voltage dividing resistors R1 and R2 are set to be larger than the resistance value of the shunt resistor as the current detection unit 3. By making the resistance values of the voltage dividing resistors R1 and R2 larger than the resistance value of the shunt resistor as the current detection unit 3 in this way, it is possible to suppress the current flowing through the voltage dividing resistors R1 and R2 and the relay Re. Therefore, the voltage dividing resistors R1 and R2 and the relay Re can be composed of inexpensive parts, and the manufacturing cost of the battery pack can be reduced.

The control unit 4 is composed of, for example, a CPU (Central Processing Unit), a multi-core CPU, and a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), and the like).

Further, in the normal mode, the control unit 4 provides information indicating the state of the battery B (voltage V1 detected by the first voltage detection unit 1, current I detected by the current detection unit 3, and charge rate of the battery B (). SOC (State Of Charge), etc.) is sent to the vehicle-side control unit that controls the running of the vehicle. It is assumed that the control unit 4 keeps the relay Re open in the normal mode. Further, for example, the control unit 4 divides the voltage applied to the shunt resistor as the current detection unit 3 by the resistance value of the shunt resistor, and the division result is the current I detected by the current detection unit 3. Further, for example, the control unit 4 has a charge rate = (charge rate of the battery B before charging or discharging) + (integrated value of the current flowing through the battery B during charging or discharging / full charge capacity of the battery B). × 100 is calculated, and the calculation result is used as the charge rate of the battery B.

Further, when the control unit 4 shifts from the normal mode to the abnormality detection mode, the control unit 4 determines whether the current detection unit 3 is normal or abnormal.
FIG. 2 is a flowchart showing an example of the operation of the control unit 4 after shifting from the normal mode to the abnormality detection mode. It is assumed that the control unit 4 keeps the relay Re open even after shifting from the normal mode to the abnormality detection mode. Further, in the abnormality detection mode, power may be supplied from the battery B to the load Lo, or power may not be supplied from the battery B to the load Lo.

First, the control unit 4 has a voltage V1 (open state battery voltage) detected by the first voltage detection unit 1 when the relay Re is in the open state and a first when the relay Re is in the open state. It is determined whether or not the voltage V2 (open state connection point voltage) detected by the voltage detection unit 2 of 2 is the same as each other (S101). In S101, the control unit 4 connects the open state battery voltage and the open state in consideration of manufacturing variations of the first voltage detection unit 1 and the second voltage detection unit 2, AD conversion error of the voltages V1 and V2, and the like. The point voltage may have a range.

Next, when the control unit 4 determines that the open state battery voltage and the open state connection point voltage are not the same (S101: No), the control unit 4 does not determine whether the current detection unit 3 is normal or abnormal. , Shift from abnormality detection mode to normal mode.

On the other hand, when the control unit 4 determines that the open state battery voltage and the open state connection point voltage are the same (S101: Yes), the relay Re is changed from the open state to the closed state (S102).
Next, in the control unit 4, the voltage V2 (closed state connection point voltage) detected by the second voltage detection unit 2 when the relay Re is closed is the connection point of the voltage dividing resistors R1 and R2. It is determined whether or not it is the same as the assumed voltage V2'of P (S103).

In S103, the control unit 4 has a voltage V1 (closed battery voltage) detected by the first voltage detection unit 1 when the relay Re is closed, and the resistance values of the voltage dividing resistors R1 and R2, respectively. Therefore, the assumed voltage V2'is obtained. For example, the control unit 4 has a voltage V1 × a voltage dividing resistance R2 resistance value / (voltage dividing) detected by the first voltage detecting unit 1 when the relay Re is closed at the assumed voltage V2 ′ = S102. By calculating the resistance value of the resistance R1 + the resistance value of the voltage dividing resistance R2), the assumed voltage V2'is obtained. Alternatively, in S103, the control unit 4 obtains the assumed voltage V2'from the open state battery voltage or the open state connection point voltage and the respective resistance values of the voltage dividing resistors R1 and R2. For example, the control unit 4 is detected by the voltage V1 or the second voltage detection unit 2 detected by the first voltage detection unit 1 when the relay Re is opened at the assumed voltage V2'= S101. The assumed voltage V2'is obtained by calculating the voltage V2 × the resistance value of the voltage dividing resistance R2 / (the resistance value of the voltage dividing resistance R1 + the resistance value of the voltage dividing resistance R2). In S103, the control unit 4 may give a range to the closed state connection point voltage in consideration of the AD conversion error of the voltage V2 and the like.

Next, when the control unit 4 determines that the closed state connection point voltage is not the same as the assumed voltage V2'(S103: No), after the relay Re is changed from the closed state to the open state (S104), the current detection unit 3 Shifts from the abnormality detection mode to the normal mode without determining whether is normal or abnormal.

On the other hand, when the control unit 4 determines that the closed state connection point voltage is the same as the assumed voltage V2'(S103: Yes), the current detected by the current detection unit 3 when the relay Re is closed. The current change amount ΔI, which is the difference between I and the current I detected by the current detection unit 3 when the relay Re is opened, is the same as the assumed current change amount ΔI ′ of the current flowing through the battery B. Whether or not it is determined (S105). That is, the control unit 4 determines that the open state battery voltage and the open state connection point voltage are the same (S101: Yes), and determines that the closed state connection point voltage is the same as the assumed voltage V2'. At this time (S103: Yes), it is determined whether or not the current change amount ΔI is the same as the assumed current change amount ΔI ′ (S105).

In S105, for example, the control unit 4 sets the current change amount ΔI = | (current I detected by the current detection unit 3 when the relay Re is opened in S101) − (relay Re in S102 or S103. The current change amount ΔI is obtained by calculating the current I) | detected by the current detection unit 3 when the closed state is set. The timing at which the current I is detected by the current detection unit 3 when the relay Re is in the open state and the timing at which the current I is detected by the current detection unit 3 when the relay Re is in the closed state. It may be configured so that the interval between the and is as short as possible. With this configuration, it is possible to accurately obtain the current change amount ΔI by suppressing the influence of fluctuations in the current flowing from the battery B to the load Lo.

Further, in S105, the control unit 4 obtains an assumed current change amount ΔI ′ based on the closed battery voltage and the respective resistance values of the voltage dividing resistors R1 and R2. For example, the control unit 4 has a voltage V1 / (voltage divider) detected by the first voltage detection unit 1 when the relay Re is closed in the assumed current change amount ΔI ′ = S102, S103, or S105. By calculating the resistance value of the resistor R1 + the resistance value of the voltage dividing resistor R2), the assumed current change amount ΔI ′ is obtained. Alternatively, in S105, the control unit 4 obtains an assumed current change amount ΔI ′ from the open state battery voltage or the open state connection point voltage and the respective resistance values of the voltage dividing resistors R1 and R2. For example, the control unit 4 detects the voltage V1 or the second voltage detection unit 2 detected by the first voltage detection unit 1 when the relay Re is opened at the assumed current change amount ΔI ′ = S101. By calculating the voltage V2 / (the resistance value of the voltage dividing resistance R1 + the resistance value of the voltage dividing resistance R2), the assumed current change amount ΔI ′ is obtained.

Next, when the control unit 4 determines that the current change amount ΔI is the same as the assumed current change amount ΔI ′ (S105: Yes), the control unit 4 determines that the current detection unit 3 is normal (S106), and sets the relay Re. The state is changed from the closed state to the open state (S104), and the mode shifts from the abnormality detection mode to the normal mode.

On the other hand, when the control unit 4 determines that the current change amount ΔI is not the same as the assumed current change amount ΔI ′ (S105: No), the control unit 4 determines that the current detection unit 3 is abnormal (S107), and the relay Re is closed. (S104), the mode shifts from the abnormality detection mode to the normal mode. When the current detection unit 3 determines that the current detection unit 3 is abnormal, the control unit 4 may be configured to send information indicating that fact to the vehicle side control unit. Upon receiving the information, the vehicle-side control unit may be configured to notify the user that the current detection unit 3 is abnormal.

As described above, since the battery pack of the embodiment does not include another current detection unit in order to determine whether the current detection unit 3 is normal or abnormal, the battery is provided with two current detection units. Manufacturing costs can be reduced compared to packs.

The present invention is not limited to the above embodiment, and various improvements and changes can be made without departing from the gist of the present invention.
FIG. 3 is a flowchart showing another example of the operation of the control unit 4 after shifting from the normal mode to the abnormality detection mode. Note that S101 to S107 shown in FIG. 3 are the same as S101 to S107 shown in FIG.

In FIG. 3, the control unit 4 shifts the relay Re from the open state to the closed state (S102) after shifting from the normal mode to the abnormality detection mode, and determines that the closed state connection point voltage is the same as the assumed voltage V2'. Then (S103: Yes), the relay Re is changed from the closed state to the open state (S100), and it is determined whether or not the open state battery voltage and the open state connection point voltage are the same as each other (S101). That is, in FIG. 3, the difference from FIG. 2 is that the order of S101 and S103 is exchanged. The control unit 4 may acquire the open state battery voltage and the open state connection point voltage in S100.

FIG. 4 is a flowchart showing still another example of the operation of the control unit 4 after shifting from the normal mode to the abnormality detection mode. Note that S101 to S107 shown in FIG. 4 are the same as S101 to S107 shown in FIG.

In FIG. 4, in the control unit 4, when the open state battery voltage and the open state connection point voltage are the same (S101: Yes), the first voltage detection unit 1 and the second voltage detection unit 2 are normal. It is determined that there is (S101a), and the relay Re is changed from the open state to the closed state (S102).

Further, when the open state battery voltage and the open state connection point voltage are not the same as each other (S101: No), the control unit 4 determines that an abnormality has occurred in the abnormality detection circuit or the first voltage detection unit 1. (S101b), the current detection unit 3 shifts from the abnormality detection mode to the normal mode without determining whether the current detection unit 3 is normal or abnormal. Examples of the abnormality that occurs in the abnormality detection circuit include "an abnormality in which the power line between the battery B and the second voltage detection unit 2 is disconnected" and "an abnormality between the battery B and the second voltage detection unit 2". There is an abnormality in which the voltage dividing resistor R1 is broken, an abnormality in which the contacts of the relay Re are welded, or an abnormality in the circuit for driving the relay Re. Further, the control unit 4 may be configured to send information indicating that an abnormality has occurred in the abnormality detection circuit or the first voltage detection unit 1 to the vehicle side control unit. Upon receiving the information, the vehicle-side control unit may be configured to notify the user that an abnormality has occurred in the abnormality detection circuit or the first voltage detection unit 1.

Further, when the control unit 4 determines that the closed state connection point voltage is the same as the assumed voltage V2'(S103: Yes), the control unit 4 determines that the voltage dividing resistors R1 and R2 and the relay Re are normal (S103a). It is determined whether or not the current change amount ΔI is the same as the assumed current change amount ΔI ′ (S105).

Further, when the control unit 4 determines that the closed state connection point voltage is not the same as the assumed voltage V2'(S103: No), it determines that an abnormality has occurred in the abnormality detection circuit (S103b), and the current detection unit 3 Shifts from the abnormality detection mode to the normal mode without determining whether is normal or abnormal. Examples of the abnormality that occurs in the abnormality detection circuit include "an abnormality in which both ends of the voltage dividing resistor R1 between the battery B and the second voltage detecting unit 2 are short-circuited" and "the relay Re is open-fixed." There are "abnormality", "abnormality in which the resistance values of the voltage dividing resistors R1 and R2 change due to temperature change or deterioration over time", or "abnormality in which the resistance value of the relay Re in the closed state increases". Further, the control unit 4 may be configured to send information indicating that an abnormality has occurred in the abnormality detection circuit to the vehicle side control unit. Upon receiving the information, the vehicle-side control unit may be configured to notify the user that an abnormality has occurred in the abnormality detection circuit.

According to the operation example of the control unit 4 shown in FIG. 4, it is possible to detect an abnormality other than the abnormality of the current detection unit 3.
FIG. 5 is a flowchart showing still another example of the operation of the control unit 4 after shifting from the normal mode to the abnormality detection mode. Note that S101 to S107 shown in FIG. 5 are the same as S101 to S107 shown in FIG.

In FIG. 5, when the control unit 4 determines that the closed state connection point voltage is the same as the assumed voltage V2'(S103: Yes), after the relay Re is changed from the closed state to the open state (S104'), the current It is determined whether or not the change amount ΔI is the same as the assumed current change amount ΔI ′ (S105).

In this configuration, in S105, the control unit 4 has a current change amount ΔI = | (current I detected by the current detection unit 3 when the relay Re is opened in S101 or S104 ′) −. (Current I detected by the current detection unit 3 when the relay Re is closed in S102 or S103) | is calculated to obtain the current change amount ΔI.

Further, in S105, the control unit 4 has a voltage V1 / (voltage dividing resistor) detected by the first voltage detecting unit 1 when the relay Re is closed in the assumed current change amount ΔI ′ = S102 or S103. By calculating the resistance value of R1 + the resistance value of the voltage dividing resistor R2), the assumed current change amount ΔI ′ is obtained. Alternatively, in S105, the control unit 4 has a voltage V1 or a second voltage V1 or a second detected by the first voltage detection unit 1 when the relay Re is opened at the assumed current change amount ΔI ′ = S101 or S104 ′. By calculating the voltage V2 / (the resistance value of the voltage dividing resistance R1 + the resistance value of the voltage dividing resistance R2) detected by the voltage detecting unit 2, the assumed current change amount ΔI ′ is obtained.

FIG. 6 is a flowchart showing still another example of the operation of the control unit 4 after shifting from the normal mode to the abnormality detection mode. Note that S101 to S104, S106, and S107 shown in FIG. 6 are the same as those of S101 to S104, S106, and S107 shown in FIG.

In FIG. 6, when the control unit 4 determines that the closed state connection point voltage is the same as the assumed voltage V2'(S103: Yes), the current change amount ΔI is obtained (S201), and the number of times the current change amount ΔI is obtained. When the number of times has not reached the predetermined number (S202: No), the relay Re is changed from the closed state to the open state (S203), and the process returns to S101.

On the other hand, when the number of times the current change amount ΔI is obtained reaches a predetermined number (S202: Yes), the control unit 4 divides the total value of all the obtained current change amounts ΔI by the predetermined number of times to change the current. The average value Ia of the quantity ΔI is obtained (S204).

Next, when the average value Ia is the same as the assumed current change amount ΔI'(S205: Yes), the control unit 4 determines that the current detection unit 3 is normal (S106), and closes the relay Re. The open state is set (S104), and the mode shifts from the abnormality detection mode to the normal mode.

On the other hand, when the average value Ia is not the same as the assumed current change amount ΔI'(S205: No), the control unit 4 determines that the current detection unit 3 is abnormal (S107), and opens the relay Re from the closed state. (S104), the mode shifts from the abnormality detection mode to the normal mode.

According to the operation example of the control unit 4 shown in FIG. 6, it is possible to accurately determine whether the current detection unit 3 is normal or abnormal by suppressing the influence of the fluctuation of the current flowing from the battery B to the load Lo. ..
Further, each operation example shown in FIGS. 3 to 6 may be appropriately combined.

1 1st voltage detection unit 2 2nd voltage detection unit 3 Current detection unit 4 Control unit B Battery R1 Voltage divider resistor R2 Voltage divider resistor Re relay Lo Load

Claims (7)

Batteries and
A first voltage detection unit that detects the voltage of the battery, and
A current detector that detects the current flowing through the battery,
Anomaly detection circuit connected in parallel to the battery
Control unit and
With
The abnormality detection circuit is
Two voltage dividing resistors that divide the voltage of the battery,
A second voltage detector that detects the voltage at the connection point of the two voltage dividing resistors,
A relay connected in series to the two voltage dividing resistors,
With
The control unit
The open state battery voltage detected by the first voltage detection unit when the relay is in the open state and the open state detected by the second voltage detection unit when the relay is in the open state. Determine if the state connection point voltages are the same as each other,
The closed state connection point voltage detected by the second voltage detector when the relay is closed is detected by the first voltage detector when the relay is closed. The assumed voltage at the connection point of the two voltage dividing resistors, which is obtained from the closed battery voltage, the open battery voltage, or the open connection point voltage, and the respective resistance values of the two voltage dividing resistors. Determine if they are the same,
When it is determined that the open state battery voltage and the open state connection point voltage are the same as each other and the closed state connection point voltage is the same as the assumed voltage, the relay is closed. The amount of change in current between the current detected by the current detection unit and the current detected by the current detection unit when the relay is opened is the closed state battery voltage, the said. Judging that it is the same as the estimated current change amount of the current flowing through the battery, which is obtained from the open state battery voltage or the open state connection point voltage and the respective resistance values of the two voltage dividing resistors, the said A battery pack characterized in that, when it is determined that the current detection unit is normal and the amount of change in the current is not the same as the amount of change in the assumed current, the current detection unit is determined to be abnormal. The battery pack according to claim 1.
A battery pack characterized in that the resistance value of each of the two voltage dividing resistors is larger than the resistance value of the shunt resistor as the current detecting unit. The battery pack according to claim 1.
When the average value of the plurality of current changes is the same as the assumed current change, the control unit determines that the current detection unit is normal, and the average value of the plurality of current changes is determined to be normal. A battery pack characterized in that if the amount of change in the assumed current is not the same, the current detection unit determines that the current is abnormal. The battery pack according to any one of claims 1 to 3.
The control unit determines that the open state battery voltage and the open state connection point voltage are the same as each other, and determines that the first and second voltage detection units are normal. pack. The battery pack according to any one of claims 1 to 3.
The battery pack, characterized in that, when the control unit determines that the closed state connection point voltage is the same as the assumed voltage, it determines that the two voltage dividing resistors and the relay are normal. The battery pack according to any one of claims 1 to 3.
When the control unit determines that the open state battery voltage and the open state connection point voltage are not the same, it determines that an abnormality has occurred in the abnormality detection circuit or the first voltage detection unit. Characterized battery pack. The battery pack according to any one of claims 1 to 3.
The battery pack is characterized in that, when the control unit determines that the closed state connection point voltage is not the same as the assumed voltage, it determines that an abnormality has occurred in the abnormality detection circuit.

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