JP7630401B2 - Battery Control Device - Google Patents

Description

The present invention relates to a battery control device.

Battery control devices that control secondary batteries composed of multiple battery cells are known. For example, a battery control device includes multiple battery monitoring circuits that repeatedly acquire status information such as the voltage and current of multiple battery cells, and a control unit that acquires status information from each battery monitoring circuit (see, for example, Patent Document 1).

JP 2015-133823 A

The battery monitoring circuit repeatedly acquires status information. When the battery monitoring circuit receives a command signal from the control unit, it transmits the status information to the control unit. In order to receive more accurate status information, it is desirable for the control unit to receive the status information from the battery monitoring circuit as soon as possible after the battery monitoring circuit acquires the status information. However, there are cases in which the lag between the timing at which the battery monitoring circuit acquires the status information and the timing at which it receives the command signal from the control unit becomes large, leaving room for improvement in terms of acquiring more accurate status information.

The present invention was made in consideration of these circumstances, and its purpose is to provide a battery control device that can obtain more accurate status information.

(1) One aspect of the present invention is a battery control device that includes a battery monitoring circuit that monitors status information of a battery cell, and a control unit that communicates with the battery monitoring circuit and receives the status information from the battery monitoring circuit by transmitting an instruction signal to the battery monitoring circuit that instructs the battery monitoring circuit to transmit the status information, the battery monitoring circuit including a first acquisition unit that repeatedly acquires the status information at a first timing, a second acquisition unit that repeatedly acquires the status information at a second timing different from the first timing, and a processing unit that, upon receiving the instruction signal, transmits the latest status information of the status information acquired by the first acquisition unit and the status information acquired by the second acquisition unit to the control unit.

(2) In the battery control device of (1) above, the period during which the first acquisition unit acquires the status information may be the same as the period during which the second acquisition unit acquires the status information.

(3) In the battery control device of (1) or (2) above, the difference between the first timing and the second timing may be half the time of the period.

(4) In any of the battery control devices described in (1) to (3), the first acquisition unit may acquire the state information, which is digital data of a physical quantity indicating a state of the battery cell, by repeatedly A/D converting the physical quantity at the first timing, and the second acquisition unit may acquire the state information, which is digital data of the physical quantity, by repeatedly A/D converting the physical quantity at the second timing.

(5) In the battery control device of (4) above, the physical quantity may be a value indicating a current value flowing through the battery cell.

(6) In the battery control device of (5) above, the physical quantity may be a potential difference across a shunt resistor connected in series to the battery cell.

As described above, the present invention provides a battery control device that can obtain more accurate status information.

1 is a diagram showing an example of a schematic configuration of a vehicle system including a battery control device according to an embodiment of the present invention. 1 is a diagram illustrating an example of a schematic configuration of a battery control device according to an embodiment of the present invention. 1 is a diagram showing an example of a schematic configuration of a battery monitoring circuit according to an embodiment of the present invention; FIG. 4 is a flow diagram of the operation of the battery monitoring circuit according to the embodiment. 1 is a timing chart of a conventional battery monitoring circuit. FIG. 2 is a diagram illustrating an example of a timing chart of the battery monitoring circuit of the present embodiment.

The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. In the drawings, the same reference numerals may be used to denote identical or similar parts, and duplicate explanations may be omitted. In addition, the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

The "connection" described below is an electrical connection. An electrical connection is a connection that allows electrical signals to be transmitted directly or indirectly. The electrical connection may be a connection via components such as a cable, resistor, capacitor, diode, or switch.

Figure 1 is a diagram showing an example of a schematic configuration of a vehicle system 100 including a battery control device 300 according to this embodiment. The vehicle system 100 is mounted on a vehicle such as a hybrid vehicle or an electric vehicle. As an example, the vehicle system 100 is mounted on an electric vehicle that uses a motor as a driving power source.

As shown in FIG. 1, the vehicle system 100 includes a secondary battery 110, a motor 120, and a power conversion device 130.

The secondary battery 110 is installed in a vehicle having the vehicle system 100, and is a nickel-metal hydride battery, a lithium-ion battery, or the like. For example, the secondary battery 110 is used as a battery in the vehicle having the vehicle system 100. For example, the power of the secondary battery 110 is used as driving power for the motor 120 and operating power for devices installed in the vehicle having the vehicle system 100.

The secondary battery 110 comprises multiple battery cell groups G (G-1 to G-n) connected in series. n is an integer of 2 or more. Multiple battery cells C are connected in series to each of the battery cell groups G-1 to G-n. The number of battery cells C in each of the battery cell groups G-1 to G-n (hereinafter also referred to as the "number of battery cells") depends on factors such as the body size of the vehicle in which the secondary battery 110 is mounted, and therefore the number of battery cells may differ depending on the vehicle having the vehicle system 100.

In each of the battery cell groups G-1 to G-n, the positive terminal of the battery cell (top cell) C located at the top is the positive terminal P1 of the secondary battery 110, and the negative terminal of the battery cell (bottom cell) C located at the bottom is the negative terminal P2 of the secondary battery 110. The positive terminal P1 and negative terminal P2 of each battery cell C are each connected to the power conversion device 130. When there is no need to distinguish between the multiple battery cell groups G-1 to G-n, they will simply be referred to as "battery cell group G."

The motor 120 is an electric motor driven by power from the power conversion device 130. For example, the motor 120 is a driving motor of a vehicle having the vehicle system 100. For example, the motor 120 is a three-phase (U, V, W) brushless motor. The motor 120 may be a motor generator. That is, the motor 120 may be used as a generator driven by the engine of the vehicle having the vehicle system 100, and may also be used as an electric motor for starting the engine. The motor 120 of this embodiment mainly operates as an electric motor and drives the wheels of the vehicle having the vehicle system 100.

The power conversion device 130 manages the secondary battery 110 and controls the driving of the motor 120. The power conversion device 130 includes a power converter 200 and a battery control device 300.

The power converter 200 boosts the output voltage output from the secondary battery 110 and converts the boosted voltage to AC. The power converter 200 then outputs the converted AC voltage to the motor 120 to drive the motor 120. The power converter 200 may also have a function of stepping down the regenerative voltage from the motor 120 at a predetermined step-down ratio and outputting it to the secondary battery 110.

The battery control device 300 controls the secondary battery 110, which is the object of control, and manages the state of the secondary battery 110. The control over the secondary battery 110 may be, for example, control to keep the voltage of the secondary battery 110 within a normal range (e.g., cell balance control), control to keep the temperature of the secondary battery 110 within a normal range, or control to eliminate an abnormality in the secondary battery 110 if one occurs.

An example of the schematic configuration of the battery control device 300 will be described below with reference to FIG. 2. FIG. 2 is a schematic configuration diagram of the battery control device 300 according to this embodiment.

The battery control device 300 includes a battery state detection unit 10, a control unit 20, a power supply circuit 30, a communication circuit 40, and a voltage generation unit 50.

The battery status detection unit 10 includes multiple battery monitoring circuits 11 (11-1 to 11-n). For example, the battery monitoring circuits 11 are integrated circuits for battery monitoring. The battery monitoring circuits 11-1 to 11-n each have the same configuration, and when there is no need to distinguish between the multiple battery monitoring circuits 11-1 to 11-n, they will simply be referred to as "battery monitoring circuits 11."

Each battery monitoring circuit 11 is electrically connected to one or more battery cells C. The battery monitoring circuit 11 monitors status information, which is information indicating the status of the battery cells C. For example, there is a one-to-one correspondence between the multiple battery monitoring circuits 11 and the multiple battery cell groups G. The battery monitoring circuit 11 is connected to the battery cell group G with which it corresponds one-to-one. In other words, the battery monitoring circuit 11-k (k is an integer from 1 to n) is connected to each of the battery cells C-k included in the battery cell group G-k with which it corresponds one-to-one.

For example, the state information is at least one of the current value Ix flowing through the battery cell C, the voltage value of the battery cell C (hereinafter referred to as the "cell voltage value"), and the temperature of the battery cell C. The current value Ix flowing through each of the multiple battery cells C connected in series is the same. Therefore, it is sufficient that at least one battery monitoring circuit 11 among the multiple battery monitoring circuits 11-1 to 11-n detects the current value Ix.

In the example shown in Figures 1 and 2, the battery monitoring circuit 11 acquires the current value Ix using a shunt resistor R. This shunt resistor R is connected in series to the battery cell C. The battery monitoring circuit 11 is connected to both ends of the shunt resistor R, and acquires the current value Ix by acquiring the potential difference of the shunt resistor R. The battery monitoring circuit 11 may also acquire the current value Ix from the measurement results of a current sensor other than the shunt resistor R.

The battery monitoring circuit 11-k is provided corresponding to the battery cell group G-k, and has multiple input terminals corresponding to the output terminals (positive or negative terminals of the battery cell C-k) of each battery cell C-k in the battery cell group G-k. The output terminals (positive or negative terminals) of each battery cell C-k and the multiple input terminals of the battery monitoring circuit 11-k are connected one-to-one by, for example, connection lines. This electrically connects both ends of each battery cell C-k to the battery monitoring circuit 11-k. The battery monitoring circuit 11-k may obtain the cell voltage value of the battery cell C by reading the potential difference between both ends of each battery cell C.

For example, the battery control device 300 has one or more temperature sensors (not shown) that measure the operating temperature of each battery cell group G. The battery monitoring circuit 11 is connected to the temperature sensor, and may obtain the temperature of the battery cell C based on the measurement result of the temperature sensor.

The battery monitoring circuit 11 communicates with the control unit 20 via the communication circuit 40 to send and receive information. When the battery monitoring circuit 11 receives an instruction signal from the control unit 20, it transmits the acquired status information to the control unit 20. The instruction signal is a signal that instructs the battery monitoring circuit 11 to transmit the status information to the control unit 20.

In this way, the battery monitoring circuit 11-k acquires status information of the battery cell C-k, and when an instruction signal is received, it transmits the acquired status information to the control unit 20 via the communication circuit 40.

In the example shown in FIG. 2, multiple battery monitoring circuits 11-1 to 11-n are daisy-chained and connected to each other by a communication line L1. This communication line L1 is a communication line capable of two-way communication. In other words, each battery monitoring circuit 11 is capable of two-way communication with an adjacent battery monitoring circuit 11.

Furthermore, among the multiple battery monitoring circuits 11-1 to 11-n connected in a daisy chain, only the battery monitoring circuit 11-n on the lowest potential side (one end side) is connected to the communication circuit 40 via the communication line L2. The communication line L2 is a communication line capable of bidirectional communication. This allows the multiple battery monitoring circuits 11-1 to 11-n connected in a daisy chain and the control unit 20 to communicate with each other via the communication circuit 40, and to send and receive information to each other. However, this is not limited, and the control unit 20 may be connected to each of the multiple battery monitoring circuits 11-1 to 11-n via a connection line. In other words, the control unit 20 only needs to be able to communicate with each of the multiple battery monitoring circuits 11-1 to 11-n, and there is no particular limitation on the connection form. The communication line L2 may include an insulating element such as a photocoupler or a pulse transformer, a communication IC, etc.

The control unit 20 has a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). In addition to the processor, the control unit 20 may also include non-volatile or volatile semiconductor memory (e.g., RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory)). For example, the control unit 20 may be a microcontroller such as an MCU.

The control unit 20 repeatedly transmits an instruction signal to the battery monitoring circuit 11 at regular intervals Ts. As a result, the control unit 20 receives status information from the battery monitoring circuit 11 at regular intervals Ts. The regular intervals Ts are the period at which the control unit 20 transmits the instruction signal.

The control unit 20 may determine an abnormality in the secondary battery 110 based on the received status information. When the control unit 20 detects an abnormality in the secondary battery 110, the control unit 20 may execute processing to turn on or flash warning lights or hazard lights provided in the vehicle, for example. When the control unit 20 detects an abnormality in the secondary battery 110, the control unit 20 may execute processing to be taken in response to the abnormality, such as notifying the user of the abnormality or executing processing to resolve the abnormality.

Below, an example of the configuration of the battery monitoring circuit 11 according to this embodiment will be described. FIG. 3 is a diagram showing an example of the configuration of the battery monitoring circuit 11 according to this embodiment. FIG. 3 shows a schematic configuration of the battery monitoring circuit 11 for acquiring the current value Ix as state information.

As shown in FIG. 3, the battery monitoring circuit 11 includes a first acquisition unit 31, a second acquisition unit 32, and a processing unit 33. The battery monitoring circuit 11 has a processor such as a CPU or an MPU. In addition to the processor, the control unit 20 may also include a non-volatile or volatile semiconductor memory (e.g., RAM, ROM, flash memory, EPROM, EEPROM. For example, the control unit 20 may be a microcontroller such as an MCU.

The first acquisition unit 31 repeatedly acquires the status information X at a first timing. The status information acquired by the first acquisition unit 31 may be referred to as "status information X1."

In the example shown in FIG. 3, the first acquisition unit 31 has an AD converter. The first acquisition unit 31 is connected to both ends of the shunt resistor R. The first acquisition unit 31 reads the potential difference Vr (analog data) between both ends of the shunt resistor R, and repeatedly executes a first acquisition process at a first timing to acquire digital data of the potential difference Vr by A/D converting the read potential difference Vr. The period of the first acquisition process is referred to as the "acquisition period T1". The digital data of the potential difference Vr is an example of the state information X1. For example, the first acquisition unit 31 holds the digital data of the potential difference Vr as the state information X1, and updates the state information X1 each time the digital data of the potential difference Vr is acquired. In other words, the first acquisition unit 31 updates the state information X1 at the first timing by repeatedly executing the first acquisition process at the first timing. Acquisition of the state information X1 is an example of updating the state information X1. In this way, the first acquisition unit 31 acquires state information X1, which is digital data of a physical quantity (such as potential difference Vr) indicating the state of the battery cell C, by repeatedly A/D converting the physical quantity at a first timing.

The second acquisition unit 32 repeatedly acquires the status information at a second timing different from the first timing. The status information acquired by the second acquisition unit 32 may be labeled as "status information X2". In the example shown in FIG. 3, the second acquisition unit 32 has an AD converter. The second acquisition unit 32 is connected to both ends of the shunt resistor R. The second acquisition unit 32 repeatedly executes a second acquisition process at a second timing, in which the potential difference Vr (analog data) between both ends of the shunt resistor R is read and the read potential difference Vr is A/D converted to acquire digital data of the potential difference Vr. The period of the second acquisition process is referred to as the "acquisition period T2". For example, the acquisition period T2 is the same as the acquisition period T1. That is, in this embodiment, the first acquisition process and the second acquisition process are only different in the timing of execution, and the execution period is the same. In addition, when the acquisition period T1 is the same as the acquisition period T2, the acquisition period T1 and the acquisition period T2 may be referred to as the acquisition period Tx.

The second timing may be different from the first timing. For example, the difference between the first timing and the second timing is half the acquisition period T1. As an example, if the acquisition period T1 is the same as the acquisition period T2 and the acquisition period T1 = acquisition period T2 = 10 ms, the difference between the first timing and the second timing is 5 ms.

For example, the second acquisition unit 32 holds digital data of the potential difference Vr as status information X2 separately from the first acquisition unit 31, and updates the status information X2 each time it acquires digital data of the potential difference Vr. In other words, the second acquisition unit 32 updates the status information X2 at the second timing by repeatedly executing the second acquisition process at the second timing. Acquisition of the status information X2 is an example of updating the status information X2. In this way, the second acquisition unit 32 acquires the status information X2, which is digital data of a physical quantity (such as the potential difference Vr) indicating the state of the battery cell C, by repeatedly A/D converting the physical quantity at the second timing.

When the processing unit 33 receives an instruction signal from the control unit 20, it transmits to the control unit 20 the latest status information out of the status information X1 acquired by the first acquisition unit 31 and the status information X2 acquired by the second acquisition unit 32. For example, out of the status information X1 and the status information X2, the status information acquired by A/D conversion at a time closer to the current time is the latest status information.

When the processing unit 33 receives an instruction signal from the control unit 20, it determines which of the status information X1 acquired by the first acquisition unit 31 and the status information X2 acquired by the second acquisition unit 32 is the latest status information. Then, the processing unit 33 transmits the latest status information of the status information X1 and the status information X2 to the control unit 20.

For example, the processing unit 33 has information on the time when the first acquisition process was executed (hereinafter referred to as "first time information") and information on the time when the second acquisition process was executed (hereinafter referred to as "second time information"). The processing unit 33 determines which of the first time information and the second time information is closer to the time when the instruction signal was received (hereinafter referred to as "instruction reception time"). If the processing unit 33 determines that the first time information is closer to the instruction reception time than the second time information, it determines that the latest information is status information X1. If the processing unit 33 determines that the second time information is closer to the instruction reception time than the first time information, it determines that the latest information is status information X2.

Figure 4 is a flow diagram of the operation of the battery monitoring circuit 11 according to this embodiment. The battery monitoring circuit 11 executes a first acquisition process for acquiring status information X1 at a first timing, in an acquisition period T1. The battery monitoring circuit 11 executes a second acquisition process for acquiring status information X2 at a second timing different from the first timing, in an acquisition period T2. The battery monitoring circuit 11 receives an instruction signal from the control unit 20 at a constant interval Ts (step S101). When the battery monitoring circuit 11 receives an instruction signal from the control unit 20, it transmits to the control unit 20 the latest status information of the information X1 and status information X2 acquired at the time of receiving the instruction signal (step S102).

The effects of this embodiment will be described below with reference to Figs. 5 and 6. Fig. 5 is a timing chart of a conventional battery monitoring circuit. Fig. 6 is an example of a timing chart of the battery monitoring circuit 11 of this embodiment. In the example shown in Figs. 5 and 6, the AD conversion performed by the battery monitoring circuit starts at the rising edge and ends at the falling edge.

As shown in FIG. 5, the conventional battery monitoring circuit updates the status information stored in the battery monitoring circuit at each acquisition period Tx by AD converting physical quantities, which are analog data such as the current value flowing through the battery cell C, at each acquisition period Tx. When the conventional battery monitoring circuit receives an instruction command at a fixed interval Ts, it transmits the status information to a control unit such as a microcomputer. Here, there is a difference ΔT between the timing of the AD conversion (the timing of the update process of the status information) and the timing of receiving the instruction signal. This difference ΔT may gradually increase. For example, when the acquisition period Tx is 8 ms and the fixed interval Ts is 10 ms, the difference ΔT gradually increases as shown in FIG. 5, and the difference ΔT becomes a maximum of 8 ms. In other words, when the conventional battery monitoring circuit receives an instruction command, it transmits status information from up to 8 ms ago to the control unit.

In the battery monitoring circuit 11 of this embodiment, two AD converters (first acquisition unit 31, second acquisition unit 32) are assigned to one physical quantity. These two AD converters perform A/D conversion at the same acquisition period Tx, but the timing at which they perform A/D conversion is different from each other. When the battery monitoring circuit 11 receives a command signal, it determines which of the AD values (status information) converted by the two AD converters is the latest. Then, the battery monitoring circuit 11 notifies the control unit 20 of the latest AD value. This allows the battery monitoring circuit 11 to reduce the deviation ΔT more than in the past. For example, the timing at which A/D conversion is performed between the first acquisition unit 31 and the second acquisition unit 32 differs by Tx × (1/2). With this configuration, the maximum deviation ΔT can be reduced by half compared to the past.

Thus, the battery control device 300 includes a battery monitoring circuit 11 that monitors the status information of the battery cells C, and a control unit 20 that communicates with the battery monitoring circuit 11 and receives status information from the battery monitoring circuit 11 by transmitting an instruction signal to the battery monitoring circuit 11 instructing the battery monitoring circuit 11 to transmit the status information. The battery monitoring circuit 11 includes a first acquisition unit 31 that repeatedly acquires the status information at a first timing, and a second acquisition unit 32 that repeatedly acquires the status information at a second timing different from the first timing. When the battery monitoring circuit 11 receives an instruction signal, the battery monitoring circuit 11 includes a processing unit 33 that transmits the latest status information of the status information acquired by the first acquisition unit 31 and the status information acquired by the second acquisition unit 32 to the control unit 20.

This configuration makes it possible to reduce the time lag ΔT between when the battery monitoring circuit 11 acquires status information and when it receives a command signal from the control unit 20, making it possible to acquire status information more accurately than before.

The first acquisition unit 31 and the second acquisition unit 32 may each be electrically connected to a current sensor that measures the current value of the battery cell C, and may each acquire digital data of the measurement result, which is an example of state information, by A/D converting the measurement results of the current sensors at different times. The current sensor may be a shunt resistor. However, the current sensor is not limited to a shunt resistor, and may be a current transformer (CT) with a transformer or a sensor with a Hall element.

In the battery monitoring circuit 11 of this embodiment, two AD converters are assigned to one physical quantity (analog data) indicating the state of the battery cell C. However, this is not limited to this, and the battery monitoring circuit 11 may assign three or more AD converters to one physical quantity. That is, the battery monitoring circuit 11 assigns two or more AD converters to one physical quantity and acquires the physical quantity by A/D conversion at different times. When the battery monitoring circuit 11 receives a command signal, it transmits the latest digital data among the AD-converted digital data acquired at different times. The A/D conversion cycles of the two or more AD converters may all be the same.

The term "unit" in the specification means a unit that processes at least one function or operation, which may be embodied as hardware or software, or a combination of hardware and software.

100...vehicle system, 110...secondary battery, 120...motor, 130...power conversion device, 200...power converter, 300...battery control device, 10...battery state detection unit, 11...battery monitoring circuit, 20...control unit, 31...first acquisition unit, 32...second acquisition unit, 33...processing unit

Claims (6)

a battery monitoring circuit that monitors state information of a battery cell;
a control unit that communicates with the battery monitoring circuit and receives the status information from the battery monitoring circuit by transmitting an instruction signal to the battery monitoring circuit to instruct the battery monitoring circuit to transmit the status information;
Equipped with
The battery monitoring circuit includes:
a first acquisition unit that repeatedly acquires the state information at a first timing;
a second acquisition unit that repeatedly acquires the state information at a second timing different from the first timing;
a processing unit that, when receiving the instruction signal, transmits to the control unit the latest of the status information acquired by the first acquisition unit and the status information acquired by the second acquisition unit;
A battery control device comprising: a period in which the first acquisition unit acquires the state information is the same as a period in which the second acquisition unit acquires the state information;
The battery control device according to claim 1 . a difference between the first timing and the second timing is half the time of the period;
The battery control device according to claim 2 . the first acquisition unit acquires the state information, which is digital data of a physical quantity indicating a state of the battery cell, by repeatedly A/D converting the physical quantity at the first timing;
the second acquisition unit acquires the state information, which is digital data of the physical quantity, by repeatedly A/D converting the physical quantity at the second timing.
The battery control device according to any one of claims 1 to 3. The physical quantity is a value indicating a current value flowing through the battery cell.
The battery control device according to claim 4. The physical quantity is a potential difference across a shunt resistor connected in series to the battery cell.
The battery control device according to claim 5.

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