JP7706312B2 - Battery Control Device - Google Patents

Description

The present invention relates to a battery control device.

Battery control devices that control secondary batteries are known. For example, a battery control device has a battery state detection unit that detects state information such as the voltage and temperature of each battery cell, a battery control unit that controls the secondary battery, and a power supply circuit that supplies power to the battery control unit. The power supply circuit is driven by power supplied from a DC power source and supplies power to the battery control unit.

JP 2001-327101 A

Here, in the battery control device, in order to continue the power supply to the battery control unit even if the power supply from the DC power source to the power circuit is stopped, a capacitor (hereinafter referred to as a "backup capacitor") may be provided between the DC power source and the power circuit (for example, Patent Document 1).

This backup capacitor receives power from a DC power source, stores an electric charge, and when the power supply from the DC power source to the power supply circuit is stopped, it discharges the electric charge to the power supply circuit, thereby allowing the power supply to the battery control unit to continue.

Backup capacitors have a large capacity because they store enough power from a DC power source to operate the power supply circuit. This can result in the component size of the backup capacitor becoming larger, so it is desirable to reduce the capacity of the backup capacitor even if only slightly.

The present invention was made in consideration of these circumstances, and its purpose is to provide a battery control device that can reduce the capacity of the backup capacitor.

(1) One aspect of the present invention is a battery control device that includes a battery state detection unit that is connected to a secondary battery and detects the state of the secondary battery, a battery control unit that communicates with the battery state detection unit and controls the secondary battery, a power supply circuit that has a power supply terminal connected to a DC power supply and operates on a power supply voltage that is a voltage input to the power supply terminal to supply power to the battery control unit, and a voltage generation unit that generates a backup voltage that is a voltage capable of operating the battery control unit by utilizing a communication signal that is a signal used for communication between the battery state detection unit and the battery control unit, and supplies the generated backup voltage to the power supply terminal.

(2) In the battery control device of (1), the backup voltage may be supplied to the power supply terminal when the voltage of the power supply terminal drops below a predetermined value.

(3) In the battery control device of (1) or (2) above, the communication signal used to generate the backup voltage may be a pulse signal transmitted from the battery state detection unit to the battery control unit.

(4) The battery control device of (3) above may further include a communication circuit for communicating between the battery state detection unit and the battery control unit, the communication circuit being connected to the power supply circuit and outputting to the voltage generation unit a first signal that is the pulse signal input from the battery state detection unit or a second signal that is a pulse signal generated from the first signal, and the voltage generation unit may generate the backup voltage by rectifying and smoothing the first signal or the second signal from the communication circuit.

(5) In the battery control device of (4) above, a range of a duty ratio of the pulse signal output from the communication circuit to the voltage generation unit includes at least a first range and a second range in which the duty ratio is higher than the first range, the battery control unit monitors the voltage of the power supply terminal, and when the voltage of the power supply terminal drops below a predetermined value, increases the duty ratio of the pulse signal from the first range to the second range, and the backup voltage may be generated by the voltage generation unit when the duty ratio of the pulse signal output from the communication circuit to the voltage generation unit is in the second range.
The battery control device according to claim 4.

(6) In the battery control device of (5) above, the battery control unit retains information on the status of the secondary battery, and when information on the status of the secondary battery is received from the battery status detection unit by communicating with the battery status detection unit, executes an update process to update the retained information on the status of the secondary battery to the information on the status of the secondary battery received from the battery status detection unit, and the update process may not be executed when the duty ratio of the pulse signal of the communication signal is within the second range.

(7) In the battery control device of (5) or (6) above, the range of the duty ratio of the pulse signal may include a third range between the first range and the second range, which is a range that cannot be used as the duty ratio of the pulse signal.

As described above, the present invention provides a battery control device that can reduce the capacity of the backup capacitor.

1 is a diagram showing an example of a schematic configuration of a vehicle equipped with 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. 4 is a diagram illustrating an example of a range of the duty ratio of a pulse signal S according to the present embodiment. FIG. FIG. 2 is a flow diagram of the operation of the battery control device according to the embodiment. 4 is a timing chart for explaining the operation of the battery control device of the present embodiment. 4 is a first modified example of the schematic configuration of the battery control device according to the present embodiment. 13 is a second modified example of the schematic configuration of the battery control device according to 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 100 equipped with a battery control device 300 according to this embodiment. The vehicle 100 is, for example, a hybrid vehicle or an electric vehicle. As an example, the vehicle 100 is an electric vehicle that uses a motor as a driving power source.

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

The secondary battery 110 is mounted on the vehicle 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 inside the vehicle 100. For example, the power of the secondary battery 110 is used as the driving power for the motor 120 and the operating power for devices mounted on the vehicle 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 100 in which the secondary battery 110 is mounted, and therefore the number of battery cells may differ depending on the vehicle 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 for the vehicle 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 100, and may also be used as an electric motor for starting the engine. The motor 120 of this embodiment operates mainly as an electric motor to drive the wheels of the vehicle 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.

Below, an example of the schematic configuration of the battery control device 300 will be described with reference to FIG. 2. FIG. 2 is a schematic configuration diagram of the battery control device 300 according to this embodiment. Note that, in the example shown in FIG. 2, a case where there are four battery cell groups G is described, but the number of battery cell groups G is not particularly limited.

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

The battery status detection unit 10 is connected to the secondary battery 110 and detects the status (hereinafter referred to as "status information") of the secondary battery 110. The status information of the secondary battery 110 is, for example, at least one of the voltage of each battery cell C (hereinafter referred to as "cell voltage") and the temperature of the secondary battery 110. The temperature of the secondary battery 110 may be the temperature of each battery cell C or the temperature of each battery cell group G. However, without being limited thereto, the status information of the secondary battery 110 may be the current flowing through the secondary battery 110.

The battery status detection unit 10 is connected to the battery control unit 20 via the communication circuit 40. The battery status detection unit 10 communicates with the battery control unit 20 via the communication circuit 40 to send and receive status information and other information. The battery status detection unit 10 determines whether or not there is an abnormality in the secondary battery based on the status information, and if it determines that there is an abnormality, it communicates with the battery control unit 20 via the communication circuit 40.

Next, the general configuration of the battery state detection unit 10 of this embodiment will be described.

For example, the battery status detection unit 10 includes multiple battery monitoring integrated circuits IC (hereinafter referred to as "battery monitoring ICs") 11.

The multiple battery monitoring ICs 11 (11-1 to 11-4) are electrically connected to the multiple battery cells C, and monitor the state of each battery cell C and each battery cell group, thereby monitoring the state of the secondary battery 110. For example, a battery monitoring IC 11 is provided corresponding to each of the battery cell groups _G1 to _G4 , and monitors the state of each battery cell C and each battery cell group. Note that the multiple battery monitoring ICs 11-1 to 11-4 each have the same configuration, and when there is no need to distinguish between the multiple battery monitoring ICs 11-1 to 11-4, they will simply be referred to as "battery monitoring IC 11."

For example, the battery monitoring IC 11 is provided corresponding to the battery cell group G, and has a number of input terminals corresponding to the output terminals (positive or negative terminals of the battery cell C) of each battery cell C in the battery cell group G. The output terminals (positive or negative terminals) of each battery cell C are connected one-to-one with the multiple input terminals of the battery monitoring IC 11, for example, by connection lines. This electrically connects both ends of each battery cell C to the battery monitoring IC 11. The battery monitoring IC 11 monitors the potential difference (hereinafter referred to as the "cell voltage value") Vcell between both ends of each battery cell C, and determines whether or not the cell voltage value Vcell of each battery cell C is abnormal. As an example, when the cell voltage value Vcell falls outside a predetermined voltage range, the battery monitoring IC 11 determines that the cell voltage value Vcell is abnormal.

The battery monitoring IC 11 monitors the temperature Tcell of the corresponding battery cell group G and determines whether or not there is an abnormality in the temperature Tcell. 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 IC 11 is connected to this temperature sensor, obtains the temperature Tcell measured by the temperature sensor, and determines whether or not there is an abnormality in the temperature Tcell. As an example, if the temperature Tcell falls outside a predetermined temperature range, the battery monitoring IC 11 determines that the temperature Tcell is abnormal.

The temperature sensor may detect the temperature Tcell in a non-contact or contact manner. For example, the temperature sensor is an infrared sensor that detects the temperature Tcell in a non-contact manner. This temperature sensor is placed, for example, in a position facing all the battery cell groups G arranged on one surface, while being supported by a scanning device or the like, and detects the temperature Tcell of each battery cell group G.

In this way, the battery monitoring IC 11-k (k is an integer from 1 to n) of this embodiment acquires the cell voltage value Vcell of each battery cell C-k and the temperature Tcell of the battery cell group G-k as status information. The battery monitoring IC 11-k determines whether there is an abnormality in the battery cell group G-k by determining whether there is an abnormality in the cell voltage value Vcell or the temperature Tcell based on the status information, and if it determines that the battery cell G-k is abnormal, it transmits a pulse signal indicating the determination result to the communication circuit 40.

In the example shown in FIG. 2, multiple battery monitoring ICs 11-1 to 11-4 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 IC 11 can communicate two-way with an adjacent battery monitoring IC 11.

Of the multiple battery monitoring ICs 11-1 to 11-4 connected in a daisy chain, only the battery monitoring IC 11-4 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 two-way communication. This allows the multiple battery monitoring ICs 11-1 to 11-4 connected in a daisy chain and the battery control unit 20 to communicate via the communication circuit 40, allowing them to send and receive information to and from each other.

In the multiple communication lines L1, each first communication line t1 is an electric wire that transmits an upstream signal output from each battery monitoring IC 11-1 to 11-4 to the battery control unit 20. In addition, in the multiple communication lines L1, each first coupling capacitor C1 is provided in the middle of each first communication line t1 and blocks the transmission of DC components between each battery monitoring IC 11-1 to 11-4.

In the multiple communication lines L1, each second communication line t2 is an electric wire that transmits a downstream signal output from the battery control unit 20 to each battery monitoring IC 11-1 to 11-4. In addition, in the multiple communication lines L1, each second coupling capacitor C2 is provided in the middle of each second communication line t2 and blocks the transmission of DC components between each battery monitoring IC 11-1 to 11-4.

That is, the first coupling capacitor C1 and the second coupling capacitor C2 in each communication line L1 are circuit elements that ensure electrical isolation in each of the battery monitoring ICs 11-1 to 11-4. Since each of the battery monitoring ICs 11-1 to 11-4 is daisy-chained to each other by multiple communication lines equipped with such first coupling capacitors C1 and second coupling capacitors C2, mutual interference can be suppressed.

The battery 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 battery control unit 20 may also include a non-volatile or volatile semiconductor memory (e.g., a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable Programmable Read Only Memory)). For example, the battery control unit 20 may be a microcontroller such as an MCU.

The battery control unit 20 operates using power supplied from the power supply circuit 30. The battery control unit 20 communicates with the battery status detection unit 10 (each of the battery monitoring ICs 11-1 to 11-4) via the communication circuit 40 and controls the secondary battery 110. The battery control unit 20 holds status information. When the battery control unit 20 receives status information from the battery status detection unit 10 by communicating with the battery status detection unit 10, it executes an update process to update the held status information to the status information received from the battery status detection unit 10.

When the status information received from the battery status detection unit 10 via the communication circuit 40 indicates an abnormality in the secondary battery 110 (e.g., an abnormality in the cell voltage Vcell or an abnormality in the temperature Tcell), the battery control unit 20 may execute processing to turn on or flash a warning light or hazard lights provided in the vehicle 100, for example. In this way, when the battery control unit 20 receives status information indicating an abnormality in the secondary battery 110, it may execute processing to be taken in response to the abnormality, such as notifying the abnormality or executing processing to resolve the abnormality.

The battery control unit 20 monitors the power supply voltage Vx applied to the power supply circuit 30. For example, the battery control unit 20 has an input terminal Iin. This input terminal Iin is connected to the power supply terminal PON of the power supply circuit 30. The battery control unit 20 can monitor the power supply voltage Vx by detecting the voltage of the input terminal Iin.

The power supply circuit 30 has a power supply terminal POW connected to a DC power supply B. The power supply terminal POW is connected to the voltage generating unit 50. The power supply circuit 30 operates by a power supply voltage Vx, which is a voltage input to the power supply terminal POW, and supplies power to the battery control unit 20. The DC power supply B outputs a DC voltage Vp. The DC power supply B is a power supply device provided inside or outside the battery control device 300, and applies the DC voltage Vp to the power supply terminal POW. For example, the DC power supply B may be the secondary battery 110, or may be a power supply that generates the DC voltage Vp from the power of the secondary battery 110. In this embodiment, the DC power supply B is connected to the power supply terminal POW via a diode D.

The power supply circuit 30 operates on a power supply voltage Vx and generates a voltage to be supplied to the battery control unit 20 from the power supply voltage Vx. The power supply circuit 30 supplies power to the battery control unit 20 by outputting this generated voltage (hereinafter, "Vc") to the battery control unit 20.

The power supply circuit 30 is, for example, an integrated circuit and has at least four terminals: a control terminal EN0, a power supply terminal POW, and an output terminal OUT.

An IG signal indicating that the ignition switch is on or off is input to the control terminal EN. This IG signal is also input to the battery control unit 20.

When an IG signal indicating that the ignition switch is turned on is input to the control terminal EN, the power supply circuit 30 supplies power to the battery control unit 20. When an IG signal indicating that the ignition switch is turned off is input to the control terminal EN, the power supply circuit 30 may stop supplying power to the battery control unit 20.

The communication circuit 40 is a communication circuit for communicating between the battery state detection unit 10 and the battery control unit 20. The communication circuit 40 is electrically connected to the voltage generation unit 50.

The communication circuit 40 includes a communication IC 41, a transformer 42, and a communication line 43.

The communication IC 41 establishes communication between the battery state detection unit 10 and the battery control unit 20. The communication IC 41 is connected to the battery control unit 20 via a communication line L3 (e.g., a serial bus such as an SPI (registered trademark) (Serial Peripheral Interface) bus).

The transformer 42 is a pulse transformer connected between the battery state detection unit 10 and the communication IC 41. For example, the transformer 42 is connected to the communication IC 41 via a communication line 43. The transformer 42 is also connected to the battery state detection unit 10, i.e., the battery monitoring IC 11-4, via a communication line L2. This allows the battery monitoring IC 11-4 and the communication IC 41 to communicate while being electrically insulated from each other.

The transformer 42 illustrated in FIG. 2 has one primary winding 42a and two secondary windings 42b and 42c that are magnetically coupled. The primary winding 42a is connected to the communication line L2.

The secondary winding 42b is connected to the communication IC 41 via the communication line 43.

The secondary winding 42c is connected to the voltage generating unit 50. The secondary winding 42b and the secondary winding 42c are not electrically connected and are independent of each other. When communication is performed from the battery state detection unit 10 to the battery control unit 20, a pulse signal S1 is input from the battery state detection unit 10 to the primary winding 42a. The transformer 42 generates a pulse signal S2 in the secondary winding 42b based on this pulse signal S1. The pulse signal S2 is output to the communication IC 41. The transformer 42 also generates a pulse signal S3 in the secondary winding 42c based on this pulse signal S1. The pulse signal S3 is output to the voltage generating unit 50.

In this way, the transformer 42 illustrated in FIG. 2 is connected to the power supply circuit 30, and generates pulse signals S2 and S3 based on the pulse signal S1 input from the battery state detection unit 10. The transformer 42 then outputs the pulse signal S2 to the communication IC 41, and outputs the pulse signal S3 to the voltage generation unit 50. Here, the pulse signal S1 is an example of a "first signal." Each of the pulse signals S2 and S3 is an example of a "second signal."

The voltage generating unit 50 has an input connected to the communication circuit 40 and an output connected to the power supply terminal POW of the power supply circuit 30 and the input terminal Iin of the battery control unit 20. The voltage generating unit 50 generates a backup voltage Vback that is a voltage capable of operating the battery control unit 20 by using a signal (hereinafter referred to as a "communication signal") used for communication between the battery state detection unit 10 and the battery control unit 20. The voltage generating unit 50 supplies the generated backup voltage Vback to the power supply terminal POW. The backup voltage may be supplied to the power supply terminal POW when the voltage of the power supply terminal POW falls below a predetermined value (hereinafter referred to as a "first threshold value") Vthf.

The communication signal used to generate the backup voltage Vback is, for example, both or either of the pulse signal S1 and the pulse signal S2. The voltage generating unit 50 generates the backup voltage Vback by, for example, using both or either of the pulse signal S1 and the pulse signal S2. Here, the use of the communication signal may be direct or indirect. The case where the communication signal is indirectly used to generate the backup voltage Vback is, for example, the case where a new signal is generated by the power of the communication signal, and the backup voltage Vback is generated by this new signal. FIG. 2 illustrates a configuration in which the communication signal is indirectly used to generate the backup voltage Vback. The voltage generating unit 50 in FIG. 2 generates the backup voltage Vback by using the pulse signal S1, and more specifically, generates the backup voltage Vback by using the pulse signal S3 generated by the pulse signal S1. In the example of FIG. 2, the voltage generating unit 50 generates the backup voltage Vback by rectifying and smoothing the pulse signal S3 from the communication circuit 40. The backup voltage Vback is set to a value higher than the first threshold value Vthf and lower than the DC voltage Vp.

Here, the duty ratio of the pulse signal S3 is the same as the duty ratio of the pulse signal S1, and varies according to the duty ratio of the pulse signal S1. In other words, when the duty ratio of the pulse signal S1 increases, the duty ratio of the pulse signal S3 increases, and when the duty ratio of the pulse signal S1 decreases, the duty ratio of the pulse signal S3 also decreases. Therefore, the battery control device 300 can adjust the duty ratio of the pulse signal S3 by adjusting the duty ratio of the pulse signal S1.

The voltage generating unit 50 shown in FIG. 2 outputs a DC voltage by rectifying and smoothing the pulse signal S3. Therefore, the battery control device 300 can adjust the voltage value of the voltage output from the voltage generating unit 50 by adjusting the duty ratio of the pulse signal S3. For example, when the voltage of the power supply terminal POW falls below the first threshold, the battery control device 300 may generate a backup voltage Vback by increasing the duty ratio of the pulse signal S3.

For example, the range of the duty ratio of the pulse signal S3 output from the communication circuit 40 to the voltage generating unit 50 includes at least a first range and a second range in which the duty ratio is higher than the first range. In this case, the backup voltage Vback may be generated by the voltage generating unit 50 when the duty ratio of the pulse signal S3 is in the second range.

Figure 3 is a diagram illustrating the range of the duty ratio of the pulse signal S3. The range of the duty ratio of the pulse signal S3 includes a third range in addition to the first and second ranges. The third range is a range that cannot be used as the duty ratio of the pulse signal S3. This third range is set between the first and second ranges. Furthermore, the third range may be set between the second range and 100%.

The range of the duty ratio of the pulse signal S1 is set to the same range as the duty ratio of the pulse signal S3. That is, the battery control device 300 controls the duty ratio of the pulse signal S3 to the first range by controlling the duty ratio of the pulse signal S1 to the first range, and controls the duty ratio of the pulse signal S3 to the second range by controlling the duty ratio of the pulse signal S1 to the second range. Therefore, the duty ratio range illustrated in FIG. 3 is set in the battery control device 300 as the duty ratio of the pulse signal S1. Then, when the voltage of the power supply terminal POW falls below the first threshold, the battery control device 300 may generate the backup voltage Vback by increasing the duty ratio of the pulse signal S1 from the first range to the second range.

The voltage generating unit 50 outputs the generated backup voltage Vback to the power supply circuit 30. For example, the voltage generating unit 50 includes a diode 51 and a capacitor 52.

The anode of the diode 51 is connected to the secondary winding 42c, and the cathode is connected to the power supply terminal POW and the input terminal Iin.

One end of capacitor 52 is connected to the cathode of diode 51, and the other end is connected to ground (GND).

The flow of operation of the battery control device 300 according to this embodiment will be described below with reference to FIG. 4. FIG. 4 is a flow diagram of the operation of the battery control device 300 according to this embodiment.

The battery control unit 20 monitors the voltage applied to the input terminal Iin. The input terminal Iin is electrically connected to the power supply terminal POW. Therefore, the battery control unit 20 determines that the voltage applied to the input terminal Iin is the power supply voltage Vx. In other words, the battery control unit 20 monitors the power supply voltage Vx.

The battery control unit 20 detects the power supply voltage Vx (step S101). The battery control unit 20 determines whether the detected power supply voltage Vx falls below a first threshold value Vthf (step S102). This first threshold value Vthf is set in advance and is a value that indicates that the power supply voltage Vx has dropped due to, for example, a momentary interruption of the DC voltage Vp.

When the battery control unit 20 determines that the power supply voltage Vx is below the first threshold value Vthf, it determines whether the ignition switch is turned off (step S103). When the battery control unit 20 does not receive an IG signal indicating that the ignition switch is turned off, it determines that the ignition switch is not turned off. When the battery control unit 20 determines that the ignition switch is not turned off, it transmits an instruction signal L1 to the battery state detection unit 10 to instruct the duty ratio of the communication signal to change from the first range to the second range (step S104). The instruction signal L1 is transmitted to the battery state detection unit 10 via the communication circuit 40. When the battery control device 300 determines that the ignition switch is turned off, it stops the supply of power from the power supply circuit 30 to the battery control unit 20. This causes the operation of the battery control unit 20 to stop (step S105).

When the battery state detection unit 10 receives the instruction signal L1, it sets the duty ratio of the communication signal to be transmitted from the battery state detection unit 10 to the battery control unit 20 from the first range to the second range. Then, the battery state detection unit 10 outputs the communication signal having a duty ratio in the second range to the communication circuit 40 (step S106). This communication signal in the second range, i.e., the pulse signal S1, is input from the battery monitoring IC 11-4 to the primary winding 42a of the transformer 42. The transformer 42 outputs a pulse signal S3 having a duty ratio in the second range from the secondary winding 42c to the voltage generation unit 50 in response to the pulse signal S1 input to the primary winding 42a.

The voltage generating unit 50 generates the backup voltage Vback by rectifying and smoothing the pulse signal S3 whose duty ratio is in the second range (step S107). The voltage generating unit 50 outputs the generated backup voltage Vback to the power supply terminal POW (step S108).

After step S108, the battery control unit 20 determines whether the power supply voltage Vx exceeds the second threshold Vthr (step S109). This second threshold Vthr is set in advance and is a value higher than the first threshold Vthf. Here, the second threshold Vthr is set to a value higher than the backup voltage Vback and lower than the DC voltage Vp.

When the battery control unit 20 determines that the power supply voltage Vx has exceeded the second threshold value Vthr, for example, assuming that the DC voltage Vp has recovered from a momentary interruption, it transmits an instruction signal L2 to the battery state detection unit 10 to instruct the battery state detection unit 10 to change the duty ratio of the communication signal from the second range to the first range (step S110). The instruction signal L2 is transmitted to the battery state detection unit 10 via the communication circuit 40. Upon receiving the instruction signal L2, the battery state detection unit 10 sets the duty ratio of the communication signal transmitted from the battery state detection unit 10 to the battery control unit 20 from the second range to the first range (step S111).

Figure 5 is a timing chart for explaining the operation of the battery control device 300 of this embodiment. As illustrated in Figure 5, assume that the DC voltage Vp is interrupted at time t1. When the DC voltage Vp is interrupted, the power supply voltage Vx gradually decreases. Then, at time t2, the DC voltage Vp falls below the first threshold Vthf. When the DC voltage Vp falls below the first threshold Vthf, the battery control device 300 generates a backup voltage Vback using the pulse signal S1 by changing the duty ratio of the pulse signal S1 from the first range to the second range and applies it to the power supply terminal POW. As a result, when a momentary interruption occurs, the power supply circuit 30 can continue to operate because the backup voltage Vback is input to the power supply terminal POW. As a result, the power supply circuit 30 can supply power to the battery control unit 20 even when the DC voltage Vp is interrupted.

For example, when the power supply voltage Vx gradually decreases, the voltage value of the voltage Vc also decreases, and when the voltage Vc falls below the reset voltage, the operation of the battery control unit 20 may stop and be initialized. In this embodiment, even if the DC voltage Vp is momentarily interrupted, power can be supplied to the battery control unit 20, so that the voltage Vc can be maintained at a level higher than the reset voltage. This makes it possible to reduce the capacity of the backup capacitor provided between the DC power supply B and the power supply circuit 30.

Here, when the duty ratio of the pulse signal S1 changes from the first range to the second range, the duty ratio of the pulse signal S2 also changes from the first range to the second range. The pulse signal S2 with a duty ratio in this second range masks the signal indicating the state of the secondary battery. Therefore, when the duty ratio of the communication signal (e.g., the pulse signal S1 or the pulse signal S2) is in the second range, the battery control unit 20 may hold the previous state (state information) of the secondary battery without performing the above-mentioned update process.

When the DC voltage Vp is interrupted and the backup voltage Vback is being output, the voltage value of the power supply voltage Vx is maintained at a voltage value between the first threshold value Vthf and the second threshold value Vthr. When the DC voltage Vp recovers from the interruption and returns to normal at time t3, the power supply voltage Vx exceeds the second threshold value Vthr. When the power supply voltage Vx exceeds the second threshold value Vthr, the battery control unit 20 determines that the DC voltage Vp has been restored and returns the pulse signal S1 from the second range to the first range. Then, the battery control unit 20 resumes the update process.

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes designs that do not deviate from the gist of the present invention.

In the example shown in FIG. 2, a backup capacitor is not provided, but this does not exclude the provision of a backup capacitor. That is, in this embodiment, a backup capacitor may or may not be provided. For example, as shown in FIG. 6, the battery control device 300 may include a backup capacitor 400 having one end connected between the cathode of the diode D and the power supply terminal POW and the other end connected to ground (GND).

2, the voltage generating unit 50 generates the backup voltage Vback by rectifying and smoothing the pulse signal S3, but is not limited thereto. For example, the voltage generating unit 50 may generate the backup voltage Vback by rectifying and smoothing the pulse signal S1, or may generate the backup voltage Vback by rectifying and smoothing the pulse signal S2. For example, the transformer 42 has two secondary windings 42b and 42c, but is not limited thereto, and may have one secondary winding 42b as shown in FIG. 7. In this case, for example, the secondary winding 42b is connected to the voltage generating unit 50, and the voltage generating unit 50 generates the backup voltage Vback by rectifying and smoothing the pulse signal S2. Note that a diode D may be provided in FIG. 7.

In the example shown in FIG. 2, the voltage generating unit 50 generates the backup voltage Vback by rectifying and smoothing the pulse signal S3 generated by the pulse signal S1, but this is not limited to the above. For example, the voltage generating unit 50 may generate the backup voltage Vback by rectifying and smoothing the pulse signal generated by the pulse signal S2.

In addition, the voltage generating unit 50 generates the backup voltage Vback using a communication signal used for communication from the battery state detection unit 10 to the battery control unit 20, but this is not limited to the above. For example, the voltage generating unit 50 may generate the backup voltage Vback using a communication signal used for communication from the battery control unit 20 to the battery state detection unit 10. However, if a communication signal used for communication from the battery control unit 20 to the battery state detection unit 10 is used, the various power consumption of the battery control unit 20 may increase, and the voltage Vc may decrease more quickly. Therefore, it is desirable to use the communication signal used for communication from the battery state detection unit 10 to the battery control unit 20 for the backup voltage Vback generated by the voltage generating unit 50.

A transformer 42 is connected between the battery monitoring IC 11-4 and the communication IC 41. However, anything that insulates the electrical connection between the battery monitoring IC 11-4 and the communication IC 41 may be connected in addition to the transformer 42, for example a photocoupler or magnetic coupler.

As described above, the battery control device 300 of this embodiment includes a battery state detection unit 10 that is connected to the secondary battery 110 and detects the state of the secondary battery 110, a battery control unit 20 that communicates with the battery state detection unit 10 and controls the secondary battery 110, a power supply circuit 30 that has a power supply terminal POW connected to a DC power supply B and operates using a power supply voltage Vx that is a voltage input to the power supply terminal POW to supply power to the battery control unit 20, and a voltage generation unit 50 that generates a backup voltage Vback using a communication signal that is a signal used for communication between the battery state detection unit 10 and the battery control unit 20 and supplies the generated backup voltage Vback to the power supply terminal POW.

With this configuration, the power required when the DC voltage Vp is momentarily interrupted can be compensated for by the backup voltage Vback. This allows the capacity of the backup capacitor to be reduced.

The backup voltage may also be supplied to the power supply terminal POW when the voltage at the power supply terminal POW falls below a predetermined value (first threshold value Vthr).

With this configuration, for example, the backup voltage Vback can be generated only when the DC voltage Vp is interrupted, thereby contributing to energy savings.

The communication signal used to generate the backup voltage Vback may be a pulse signal transmitted from the battery state detection unit 10 to the battery control unit 20.

This configuration allows the backup voltage Vback to be generated without using the power of the battery control unit 20, thereby suppressing the decrease in voltage Vc.

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, 110...secondary battery, 120...motor, 130...power conversion device, 200...power converter, 300...battery control device, 10...battery state detection unit, 11...battery monitoring IC, 20...battery control unit, 30...power supply circuit, 40...communication circuit, 41...communication IC, 42...transformer, 50...voltage generation unit

Claims (7)

a battery state detection unit connected to a secondary battery and detecting a state of the secondary battery;
a battery control unit that communicates with the battery state detection unit and controls the secondary battery;
a power supply circuit having a power supply terminal connected to a DC power supply, the power supply circuit being operated by a power supply voltage that is a voltage input to the power supply terminal to supply power to the battery control unit;
a voltage generating unit that generates a backup voltage capable of operating the battery control unit by utilizing a communication signal that is a signal used for communication between the battery state detecting unit and the battery control unit, and supplies the generated backup voltage to the power supply terminal;
A battery control device comprising: the backup voltage is supplied to the power supply terminal when the voltage of the power supply terminal drops below a predetermined value.
The battery control device according to claim 1 . The communication signal used to generate the backup voltage is a pulse signal transmitted from the battery state detection unit to the battery control unit.
The battery control device according to claim 1 or 2. a communication circuit for communicating between the battery state detection unit and the battery control unit, the communication circuit being connected to the power supply circuit and outputting to the voltage generation unit a first signal which is the pulse signal input from the battery state detection unit or a second signal which is a pulse signal generated based on the first signal;
the voltage generating unit generates the backup voltage by rectifying and smoothing the first signal or the second signal from the communication circuit.
The battery control device according to claim 3. a range of a duty ratio of the pulse signal output from the communication circuit to the voltage generating unit includes at least a first range and a second range in which the duty ratio is higher than that of the first range;
the battery control unit monitors a voltage at the power supply terminal, and when the voltage at the power supply terminal drops below a predetermined value, increases the duty ratio of the pulse signal from the first range to the second range;
the backup voltage is generated by the voltage generating unit when the duty ratio of the pulse signal output from the communication circuit to the voltage generating unit is within the second range.
The battery control device according to claim 4. the battery control unit holds information on a state of the secondary battery, and when the battery control unit receives information on the state of the secondary battery from the battery state detection unit by communicating with the battery state detection unit, executes an update process to update the held information on the state of the secondary battery to the information on the state of the secondary battery received from the battery state detection unit;
The update process is not executed when the duty ratio of the pulse signal of the communication signal is within the second range.
The battery control device according to claim 5. a range of the duty ratio of the pulse signal includes a third range between the first range and the second range, the third range being a range that cannot be used as the duty ratio of the pulse signal;
The battery control device according to claim 5 or 6.

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