Battery control device

Abstract

To provide a battery control device capable of reducing the capacity of a backup capacitor.SOLUTION: A battery control device comprises: a battery state detection unit connected to a secondary battery to detect a state of the secondary battery; a battery control unit that communicates to the battery state detection unit to control the secondary battery; a power supply circuit having a power supply terminal connected to a DC power supply, and operated by a power supply voltage being voltage input to the power supply terminal to supply power to the battery control unit; and a voltage generating unit that utilizes a communication signal being a signal used for a communication between the battery state detection unit and the battery control unit to generate a backup voltage being voltage that can operate the battery control unit, and supplies the generated back up voltage to the power supply terminal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a battery control device.

Background Art

[0002] A battery control device for controlling a secondary battery is known. For example, the battery control device includes 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.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the battery control device, in order to continue to supply power to the battery control unit even when the power supply from the DC power source to the power supply circuit stops, for example, a capacitor (hereinafter referred to as a "backup capacitor") may be provided between the DC power source and the power supply circuit (for example, Patent Document 1).

[0005] This backup capacitor stores electric charge by receiving power supply from the DC power source, and discharges the electric charge to the power supply circuit when the power supply from the DC power source to the power supply circuit stops, thereby continuing to supply power to the battery control unit.

[0006] The backup capacitor is large in capacity in order to store the power that can operate the power supply circuit from the DC power source. Therefore, the component size of the backup capacitor may increase, and it is desired to reduce the capacity of the backup capacitor as much as possible.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a battery control device capable of reducing the capacitance of a backup capacitor.

Means for Solving the Problems

[0008] (1) One aspect of the present invention is a battery control device that is connected to a secondary battery, detects the state of the secondary battery, communicates with the battery state detection unit, controls the secondary battery, and has a power supply terminal connected to a DC power supply. A power supply circuit that operates by a power supply voltage that is the voltage input to the power supply terminal and supplies power to the battery control unit, and a backup voltage that is a voltage capable of operating the battery control unit using a communication signal that is a signal used for communication between the battery state detection unit and the battery control unit. And a voltage generation unit that generates the generated backup voltage and supplies it to the power supply terminal.

[0009] (2) The battery control device according to (1) above, wherein the backup voltage may be supplied to the power supply terminal when the voltage of the power supply terminal drops below a predetermined value.

[0010] (3) The battery control device according to (1) or (2) above, wherein the communication signal used for generating the backup voltage may be a pulse signal transmitted from the battery state detection unit toward the battery control unit.

[0011] (4) The battery control device according to (3) above, further comprising 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 the first signal being the pulse signal input from the battery state detection unit. Or a second signal that is a pulse signal generated by the first signal is output to the voltage generation unit, 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.

[0012] (5) The battery control device according to (4) above, wherein the range of the 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 having a higher duty ratio 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.

[0013] (6) The battery control device according to (5) above, wherein the battery control unit holds information on the state of the secondary battery, and when receiving 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 of updating the information on the secondary battery held by the information on the state of the secondary battery received from the battery state detection unit, and the update process may not be executed when the duty ratio of the pulse signal of the communication signal is in the second range. Status of which is updated to the information on the state of the secondary battery received from the battery state detection unit, and the update process may not be executed when the duty ratio of the pulse signal of the communication signal is in the second range.

[0014] (7) The battery control device according to (5) or (6) above, wherein the range of the duty ratio of the pulse signal may include a third range that is a range in which the duty ratio of the pulse signal cannot be used between the first range and the second range.

Effect of the Invention

[0015] As described above, according to the present invention, it is possible to provide a battery control device capable of reducing the capacitance of the backup capacitor.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0017] Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. Also, not all combinations of features described in the embodiments are essential for the solution means of the invention. In the drawings, the same or similar parts may be denoted by the same reference numerals, and redundant explanations may be omitted. Also, the shape and size of elements in the drawings may be exaggerated for clearer explanation.

[0018] The "connection" described below refers to an electrical connection. An electrical connection means that electrical signals are connected so as to be directly or indirectly transmissible. The electrical connection may be a connection via components such as cables, resistors, capacitors, diodes, and switches.

[0019] FIG. 1 is a diagram showing an example of the schematic configuration of a vehicle 100 including a battery control device 300 according to the present embodiment. The vehicle 100 is a vehicle such as a hybrid vehicle or an electric vehicle, for example. As an example, the vehicle 100 is an electric vehicle having a motor as a driving power source.

[0020] As shown in FIG. 1, the vehicle 100 includes a secondary battery 110, a motor 120, and a power conversion device 130.

[0021] 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 in the vehicle 100. For example, the power of the secondary battery 110 is used as driving power for the motor 120 and operating power for devices mounted on the vehicle 100.

[0022] The secondary battery 110 includes a plurality of battery cell groups G (G-1 to G-n) connected in series. n is an integer of 2 or more. A plurality of 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 the vehicle body size of the vehicle 100 on which the secondary battery 110 is mounted, etc., and thus the number of battery cells may differ depending on the vehicle 100.

[0023] In each of the battery cell groups G-1 to G-n, the positive electrode terminal of the topmost battery cell (topmost cell) C is the positive electrode terminal P1 of the secondary battery 110, and the negative electrode terminal of the lowermost battery cell (lowermost cell) C is the negative electrode terminal P2 of the secondary battery 110. The positive electrode terminal P1 and the negative electrode terminal P2 of each battery cell C are connected to the power conversion device 130, respectively. When not distinguishing each of the plurality of battery cell groups G-1 to G-n, it is simply denoted as "battery cell group G".

[0024] 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. Note that 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 also as an electric motor for starting the engine. The motor 120 of the present embodiment mainly operates as an electric motor and drives the wheels of the vehicle 100.

[0025] 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.

[0026] The power converter 200 boosts the output voltage output from the secondary battery 110 and converts the boosted voltage into alternating current. Then, the power converter 200 drives the motor 120 by outputting the converted alternating current voltage to the motor 120. Note that the power converter 200 may 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.

[0027] The battery control device 300 controls the secondary battery 110 that is the control target and manages the state of the secondary battery 110. The control of the secondary battery 110 may be, for example, control for maintaining the voltage of the secondary battery 110 within a normal range (for example, cell balancing control), control for maintaining the temperature of the secondary battery 110 within a normal range, or control for eliminating an abnormality when an abnormality occurs in the secondary battery 110.

[0028] Hereinafter, 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 the present embodiment. In the example shown in FIG. 2, the case where there are four battery cell groups G is described, but the number of battery cell groups G is not particularly limited.

[0029] 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.

[0030] The battery state detection unit 10 is connected to the secondary battery 110 and detects the state of the secondary battery 110 (hereinafter referred to as "state information"). The state 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, it is not limited thereto, and the state information of the secondary battery 110 may be the current flowing through the secondary battery 110.

[0031] The battery state detection unit 10 is connected to the battery control unit 20 via the communication circuit 40. The battery state detection unit 10 communicates with the battery control unit 20 via the communication circuit 40 and transmits and receives state information and other information. The battery state detection unit 10 determines the presence or absence of an abnormality in the secondary battery based on the state information. When it is determined that there is an abnormality, the battery state detection unit 10 communicates with the battery control unit 20 via the communication circuit 40.

[0032] Next, the schematic configuration of the battery state detection unit 10 of the present embodiment will be described.

[0033] For example, the battery state detection unit 10 includes a plurality of integrated circuits IC for battery monitoring (hereinafter referred to as "battery monitoring IC") 11.

[0034] The plurality of battery monitoring ICs 11 (11-1 to 11-4) are electrically connected to the plurality of battery cells C and monitor the state of the secondary battery 110 by monitoring the state of each battery cell C and each battery cell group. For example, the battery monitoring IC 11 is provided corresponding to each battery cell group G1 to G4 and monitors the state of each battery cell C and each battery cell group. Note that the plurality of battery monitoring ICs 11-1 to 11-4 have the same configuration, and when not distinguishing each of the plurality of battery monitoring ICs 11-1 to 11-4, they are simply referred to as "battery monitoring IC 11".

[0035] For example, the battery monitoring IC 11 is provided corresponding to the battery cell group G, and includes a plurality of input terminals respectively corresponding to the output terminals (the positive electrode terminal or the negative electrode terminal of the battery cell C) of each battery cell C in the battery cell group G. Then, the output terminals (plus terminal or minus terminal) of each battery cell C and the plurality of input terminals of the battery monitoring IC 11 are connected one-to-one by, for example, connection lines. Thereby, both ends of each battery cell C and the battery monitoring IC 11 are electrically connected. The battery monitoring IC 11 monitors the potential difference (hereinafter referred to as "cell voltage value") Vcell between both ends of each battery cell C, and determines the presence or absence of an abnormality in the cell voltage value Vcell of each battery cell C. As an example, when the cell voltage value Vcell is outside a predetermined voltage range, the battery monitoring IC 11 determines that the cell voltage value Vcell is abnormal.

[0036] The battery monitoring IC 11 monitors the temperature Tcell of the corresponding battery cell group G, and determines the presence or absence of an abnormality in the temperature Tcell. For example, the battery control device 300 has one or more temperature sensors (not shown) for measuring the operating temperature of each battery cell group G. The battery monitoring IC 11 is connected to this temperature sensor, acquires the temperature Tcell measured by the temperature sensor, and determines the presence or absence of an abnormality in the temperature Tcell. As an example, when the temperature Tcell is outside a predetermined temperature range, the battery monitoring IC 11 determines that the temperature Tcell is abnormal.

[0037] The detection method of the temperature Tcell in the temperature sensor may be non-contact or contact. For example, the temperature sensor is an infrared sensor, and detects the temperature Tcell in a non-contact manner. This temperature sensor is arranged, for example, in a state supported by a scanning device or the like at a position where it can face all the battery cell groups G arranged on one surface, and detects the temperature Tcell of each battery cell group G.

[0038] As described above, 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 state information. The battery monitoring IC 11-k determines the presence or absence of an abnormality in the battery cell group G-k by determining the presence or absence of an abnormality in the cell voltage value Vcell or the temperature Tcell based on the state information. When it is determined that the battery cell G-k is abnormal, a pulse signal indicating the determination result is transmitted toward the communication circuit 40.

[0039] In the example shown in FIG. 2, a plurality of battery monitoring ICs 11-1 to 11-4 are daisy-chain connected and are connected to each other by a communication line L1. This communication line L1 is a communication line capable of bidirectional communication. That is, each battery monitoring IC 11 can communicate bidirectionally with an adjacent battery monitoring IC 11.

[0040] Also, among the plurality of 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 a communication line L2. The communication line L2 is a communication line capable of bidirectional communication. Thereby, the plurality of battery monitoring ICs 11-1 to 11-4 connected in a daisy chain and the battery control unit 20 can communicate with each other via the communication circuit 40 and can transmit and receive mutual information.

[0041] In the plurality of communication lines L1, each first communication line t1 is a wire that transmits an upstream signal output from each of the battery monitoring ICs 11-1 to 11-4 to the battery control unit 20. Also, in the plurality of communication lines L1, each first coupling capacitor C1 is provided in the middle of each first communication line t1 and blocks the transmission of the DC component between each of the battery monitoring ICs 11-1 to 11-4.

[0042] Among the plurality of communication lines L1, each second communication line t2 is an electric wire that transmits the downstream signal output from the battery control unit 20 to each of the battery monitoring ICs 11-1 to 11-4. Also, among the plurality of communication lines L1, each second coupling capacitor C2 is provided in the middle of each second communication line t2 and blocks the transmission of the DC component between each of the battery monitoring ICs 11-1 to 11-4.

[0043] 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-chain connected to each other by a plurality of communication lines having such a first coupling capacitor C1 and a second coupling capacitor C2, mutual interference can be suppressed.

[0044] The battery control unit 20 has a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). Also, the battery control unit 20 may include a non-volatile or volatile semiconductor memory (for example, RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory)) in addition to the processor. For example, the battery control unit 20 may be a microcontroller such as an MCU.

[0045] The battery control unit 20 operates by the power supplied from the power supply circuit 30. The battery control unit 20 communicates with the battery state detection unit 10 (each battery monitoring IC 11-1 to 11-4) via the communication circuit 40 and controls the secondary battery 110. The battery control unit 20 holds state information. When the battery control unit 20 receives state information from the battery state detection unit 10 by communicating with the battery state detection unit 10, it executes an update process of updating the held state information with the state information received from the battery state detection unit 10.

[0046] When the state information received by the battery control unit 20 from the battery state detection unit 10 via the communication circuit 40 indicates an abnormality of the secondary battery 110 (for example, an abnormality of the cell voltage Vcell or the temperature Tcell), the battery control unit 20 may execute a process for turning on or flashing a warning lamp or a hazard provided in the vehicle 100, for example. In this way, when the battery control unit 20 receives state information indicating an abnormality of the secondary battery 110, it may execute processes to be taken for the abnormality, such as notifying the abnormality or executing a process for eliminating the abnormality.

[0047] 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.

[0048] The power supply circuit 30 has a power supply terminal POW connected to the DC power supply B. The power supply terminal POW is connected to the voltage generation unit 50. The power supply circuit 30 operates with the power supply voltage Vx, which is the 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 the present embodiment, the DC power supply B is connected to the power supply terminal POW via the diode D.

[0049] The power supply circuit 30 operates with the power supply voltage Vx and generates a voltage to be supplied from the power supply voltage Vx to the battery control unit 20. The power supply circuit 30 supplies power to the battery control unit 20 by outputting the generated voltage (hereinafter, “Vc”) to the battery control unit 20.

[0050] 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.

[0051] An IG signal indicating that the ignition switch has been turned on or off is input to the control terminal EN. This IG signal is also input to the battery control unit 20.

[0052] When an IG signal indicating that the ignition switch has been 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 has been turned off is input to the control terminal EN, the power supply circuit 30 may stop supplying power to the battery control unit 20.

[0053] 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.

[0054] The communication circuit 40 includes a communication IC 41, a transformer 42, and a communication line 43.

[0055] 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 (for example, a serial bus such as an SPI (registered trademark) (Serial Peripheral Interface) bus).

[0056] 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 the communication line 43. Also, the transformer 42 is connected to the battery state detection unit 10, that is, the battery monitoring IC 11-4, via the communication line L2. Thereby, the battery monitoring IC 11-4 and the communication IC 41 can communicate with each other in an electrically insulated state.

[0057] The transformer 42 illustrated in FIG. 2 has one primary winding 42a and two secondary windings 42b, 42c magnetically coupled. The primary winding 42a is connected to the communication line L2.

[0058] The secondary winding 42b is connected to the communication IC 41 via the communication line 43.

[0059] The secondary winding 42c is connected to the voltage generation 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 by this pulse signal S1. The pulse signal S2 is output to the communication IC 41. Also, the transformer 42 generates a pulse signal S3 in the secondary winding 42c by this pulse signal S1. The pulse signal S3 is output to the voltage generation unit 50.

[0060] As described above, the transformer 42 illustrated in FIG. 2 is connected to the power supply circuit 30 and generates a pulse signal S2 and a pulse signal S3 in response to the pulse signal S1 input from the battery state detection unit 10. Then, the transformer 42 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 the "first signal". Each of the pulse signal S2 and the pulse signal S3 is an example of the "second signal".

[0061] The voltage generation 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 generation unit 50 generates a backup voltage Vback, which is a voltage capable of operating the battery control unit 20, using a signal (hereinafter referred to as the "communication signal") used for communication between the battery state detection unit 10 and the battery control unit 20. The voltage generation unit 50 supplies the generated backup voltage Vback to the power supply terminal POW. Note that the backup voltage may be supplied to the power supply terminal POW when the voltage of the power supply terminal POW drops below a predetermined value (hereinafter referred to as the "first threshold value") Vthf.

[0062] The communication signal used to generate the backup voltage Vback is, for example, either or both of the pulse signal S1 and the pulse signal S2. The voltage generation unit 50 generates the backup voltage Vback using, for example, either or both of the pulse signal S1 and the pulse signal S2. Here, using the communication signal may be either direct use or indirect use. The case of indirectly using the communication signal to generate the backup voltage Vback is, for example, when 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 backup voltage Vback is generated by indirectly using the communication signal. The voltage generation unit 50 in FIG. 2 generates the backup voltage Vback using the pulse signal S1. More specifically, the backup voltage Vback is generated using the pulse signal S3 generated by the pulse signal S1. In the example of FIG. 2, the voltage generation 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 Vthf and lower than the DC voltage Vp.

[0063] 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.

[0064] The voltage generation 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 generation unit 50 by adjusting the duty ratio of the pulse signal S3. For example, when the voltage of the power supply terminal POW drops below the first threshold value, the battery control device 300 may increase the duty ratio of the pulse signal S3 to generate the backup voltage Vback.

[0065] For example, the range of the duty ratio of the pulse signal S3 output from the communication circuit 40 to the voltage generation unit 50 includes at least a first range and a second range having a higher duty ratio than the first range. In this case, the backup voltage Vback may be generated by the voltage generation unit 50 when the duty ratio of the pulse signal S3 is in the second range.

[0066] FIG. 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 range and the second range. 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 range and the second range. Further, the third range may be set between the second range and 100%.

[0067] The range of the duty ratio of the pulse signal S1 is set in the same manner as the range of 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 be in the first range by controlling the duty ratio of the pulse signal S1 to be in the first range, and controls the duty ratio of the pulse signal S3 to be in the second range by controlling the duty ratio of the pulse signal S1 to be in the second range. Therefore, the range of the duty ratio illustrated in FIG. 3 is set in the battery control device 300 as the duty ratio of the pulse signal S1. When the voltage of the power supply terminal POW drops below the first threshold value, the battery control device 300 may increase the duty ratio of the pulse signal S1 from the first range to the second range to generate the backup voltage Vback.

[0068] The voltage generation unit 50 outputs the generated backup voltage Vback to the power supply circuit 30. For example, the voltage generation unit 50 includes a diode 51 and a capacitor 52.

[0069] 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.

[0070] One end of the capacitor 52 is connected to the cathode of the diode 51, and the other end is connected to the ground (GND).

[0071] Hereinafter, the operation flow of the battery control device 300 according to the present embodiment will be described with reference to FIG. 4. FIG. 4 is a flowchart of the operation of the battery control device 300 according to the present embodiment.

[0072] 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 voltage applied to the input terminal Iin by the battery control unit 20 is the power supply voltage Vx. In other words, the battery control unit 20 monitors the power supply voltage Vx.

[0073] 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 is lower than the first threshold value Vthf (step S102). This first threshold value Vthf is set in advance and is, for example, a value indicating that the power supply voltage Vx has decreased due to an interruption of the DC voltage Vp or the like.

[0074] When the battery control unit 20 determines that the power supply voltage Vx has fallen below the first threshold value Vthf, it determines whether the ignition switch has been turned off (step S103). If the battery control unit 20 has not received the IG signal indicating that the ignition switch has been turned off, it determines that the ignition switch has not been turned off. When the battery control unit 20 determines that the ignition switch has not been turned off, it transmits an instruction signal L1 to the battery state detection unit 10, instructing it to change the duty ratio of the communication signal 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 has been turned off, it stops supplying power from the power supply circuit 30 to the battery control unit 20. As a result, the operation of the battery control unit 20 stops (step S105).

[0075] When the battery state detection unit 10 receives the instruction signal L1, it sets the duty ratio of the communication signal 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 a communication signal with a duty ratio in the second range to the communication circuit 40 (step S106). This communication signal in the second range, that is, 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 with 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.

[0076] The voltage generation unit 50 generates a backup voltage Vback by rectifying and smoothing the pulse signal S3 with a duty ratio in the second range (step S107). The voltage generation unit 50 outputs the generated backup voltage Vback to the power supply terminal POW (step S108).

[0077] After step S108, the battery control unit 20 determines whether the power supply voltage Vx exceeds the second threshold value Vthr (step S109). This second threshold value Vthr is preset and is a value higher than the first threshold value Vthf. Here, the second threshold value Vthr is set to a value higher than the backup voltage Vback and lower than the DC voltage Vp.

[0078] 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 an interruption, it transmits an instruction signal L2 to the battery state detection unit 10 to instruct it 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. When the battery state detection unit 10 receives the instruction signal L2, it 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).

[0079] FIG. 5 is a timing chart for explaining the operation of the battery control device 300 of the present embodiment. As illustrated in FIG. 5, assume that the DC voltage Vp has an interruption at time t1. When the DC voltage Vp has an interruption, the power supply voltage Vx gradually decreases. Then, at time t2, the DC voltage Vp falls below the first threshold value Vthf. When the DC voltage Vp falls below the first threshold value Vthf, the battery control device 300 changes the duty ratio of the pulse signal S1 from the first range to the second range, and uses the pulse signal S1 to generate the backup voltage Vback and apply it to the power supply terminal POW. As a result, when an interruption occurs, the backup voltage Vback is input to the power supply terminal POW, so that the power supply circuit 30 can continue its operation. As a result, even when the DC voltage Vp has an interruption, the power supply circuit 30 can supply power to the battery control unit 20.

[0080] For example, when the power supply voltage Vx gradually decreases, the voltage value of the voltage Vc also decreases. 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 when the DC voltage Vp is 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. Thereby, the capacitance of the backup capacitor provided between the DC power supply B and the power supply circuit 30 can be reduced.

[0081] 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 the 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 (for example, the pulse signal S1 or the pulse signal S2) is in the second range, the battery control unit 20 may hold the state (state information) of the previous secondary battery without executing the above-described update process.

[0082] 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 Vthf and the second threshold 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 Vthr. Therefore, when the power supply voltage Vx exceeds the second threshold Vthr, the battery control unit 20 causes the pulse signal S1 to return from the second range to the first range as if the DC voltage Vp has returned. Then, the battery control unit 20 resumes the update process.

[0083] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and designs and the like within the scope not departing from the gist of the present invention are also included.

[0084] In the example shown in FIG. 2, no backup capacitor is provided, but this does not exclude the possibility of providing a backup capacitor. That is, in this embodiment, the 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 the ground (GND).

[0085] In the example shown in FIG. 2, the voltage generation unit 50 generates the backup voltage Vback by rectifying and smoothing the pulse signal S3, but it is not limited thereto. For example, the voltage generation 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, although the transformer 42 has been described as having two secondary windings 42b and 42c, it is not limited thereto, and as shown in FIG. 7, it may have one secondary winding 42b. In this case, for example, the secondary winding 42b is connected to the voltage generation unit 50, and the voltage generation unit 50 generates the backup voltage Vback by rectifying and smoothing the pulse signal S2. Note that in FIG. 7, the diode D may be provided.

[0086] In the example shown in FIG. 2, the voltage generation unit 50 generates the backup voltage Vback by rectifying and smoothing the pulse signal S3 generated by the pulse signal S1, but it is not limited thereto. For example, the voltage generation unit 50 may generate the backup voltage Vback by rectifying and smoothing the pulse signal generated by the pulse signal S2.

[0087] In addition, although the voltage generation unit 50 generates the backup voltage Vback using the communication signal used for communication from the battery state detection unit 10 to the battery control unit 20, it is not limited to this. For example, the voltage generation unit 50 may generate the backup voltage Vback using the communication signal used for communication from the battery control unit 20 to the battery state detection unit 10. However, if the communication signal used for communication from the battery control unit 20 to the battery state detection unit 10 is used, various power consumptions of the battery control unit 20 increase, and the voltage Vc may decrease earlier. 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 generation unit 50.

[0088] Also, a transformer 42 is connected between the battery monitoring IC 11-4 and the communication IC 41. However, between the battery monitoring IC 11-4 and the communication IC 41, any device that insulates the electrical connection may be used. In addition to the transformer 42, for example, a photocoupler or a magnetic coupler may be connected.

[0089] As described above, the battery control device 300 of the present embodiment is connected to the secondary battery 110 and includes a battery state detection unit 10 that 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 the DC power supply B and operates with the power supply voltage Vx, which is the 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 the backup voltage Vback using the communication signal, which is the 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.

[0090] With such a configuration, the power at the time of momentary interruption of the DC voltage Vp can be compensated for by the backup voltage Vback. Therefore, the capacitance of the backup capacitor can be reduced.

[0091] Further, the backup voltage may be supplied to the power supply terminal POW when the voltage of the power supply terminal POW drops below a predetermined value (first threshold value Vthr).

[0092] With such a configuration, for example, the backup voltage Vback can be generated only when the DC voltage Vp has an instantaneous interruption, contributing to energy reduction.

[0093] Also, the communication signal used for generating the backup voltage Vback may be a pulse signal transmitted from the battery state detection unit 10 toward the battery control unit 20.

[0094] With such a configuration, the backup voltage Vback can be generated without using the power of the battery control unit 20, and a decrease in the voltage Vc can be suppressed.

[0095] The term "… unit" described 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.

Explanation of Reference Numerals

[0096] 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

1. A battery state detection unit connected to a secondary battery and detecting 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 having a power supply terminal connected to a DC power supply, operating with a power supply voltage that is the voltage input to the power supply terminal, and supplying power to the battery control unit; A voltage generation unit that generates a backup voltage, which is a voltage capable of operating the battery control unit, using 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; A battery control device comprising:

2. 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.

3. The communication signal used for generating the backup voltage is a pulse signal transmitted from the battery state detection unit toward the battery control unit, The battery control device according to claim 1 or 2.

4. The battery control device further includes a communication circuit for communicating between the battery state detection unit and the battery control unit. The communication circuit is connected to the power supply circuit and outputs 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 by the first signal, to the voltage generation unit, The voltage generation 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.

5. The range of the 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 where 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, The backup voltage is 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. The battery control unit holds information on the state of the secondary battery, and when it receives information on the state of the secondary battery from the battery state detection unit by communicating with the battery state detection unit, it executes an update process of updating the information on the state of the secondary battery held by 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. **Claim 7** The range of the duty ratio of the pulse signal includes a third range that is a range that cannot be used as the duty ratio of the pulse signal between the first range and the second range. The battery control device according to claim 5 or 6.

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