Power supply system and method for controlling power supply system

Abstract

This power supply system 100 includes a battery sensor 2 and a management ECU 10. When a discharge current of a battery 1 measured by the battery sensor 2 is equal to or more than a predetermined dark current threshold, the management ECU 10 transmits a control signal to sleep to load ECUs 11-13.

Description

Power supply system and control method of power supply system

[0001] The present invention relates to a power supply system and a control method for a power supply system. This application claims priority based on Japanese Patent Application No. 2023-217280 filed on December 22, 2023, and for designated states where incorporation by reference of documents is permitted, the contents of the above application are incorporated by reference into this application and made a part of the description of this application.

[0002] A shared power supply that monitors the status of each control device is known (for example, see Patent Document 1). In the shared power supply described in Patent Document 1, the MPU installed in each control device monitors the power supply voltage supplied from the shared power supply, and the voltage monitoring results are transmitted to the MPU of the shared power supply via a communication circuit. If the MPU of the shared power supply does not receive an information update from the MPU of the control device at a predetermined interval, it determines that the MPU has run out of control or has failed, and restarts the MPU of the control device by controlling the buffer.

[0003] JP 2013-193721 A

[0004] In the shared power supply device described in Patent Document 1, the MPUs mounted on the respective control devices operate to detect abnormalities in the MPUs, which causes a problem of large power consumption during abnormality diagnosis.

[0005] An object of the present invention is to provide a power supply system and a method for controlling the power supply system that can reduce power consumption during abnormality diagnosis.

[0006] The present invention solves the above problem by having the management ECU send a control signal to the ECU to put it into sleep mode when the discharge current of the battery measured by the battery sensor is equal to or greater than a predetermined dark current threshold.

[0007] According to the present invention, it is possible to reduce power consumption during abnormality diagnosis.

[0008] Fig. 1 is a schematic diagram of the power supply system according to this embodiment. Fig. 2 is a graph illustrating the relationship between the operating state of the ECU, the state of the power supply, and the number of functioning ECUs. Fig. 3 is a graph illustrating the relationship between the operating state of the ECU, the state of the power supply, and the magnitude of current consumption.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply system according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0010] 1 is a schematic diagram of a power supply system 100 according to this embodiment. In this embodiment, the power supply system is mounted on a vehicle equipped with a communication network 40 and a battery 1. The vehicle may be a vehicle powered by an engine (ICE vehicle), a hybrid vehicle equipped with an engine and a motor, or an electric vehicle.

[0011] 1, the power supply system 100 includes a battery 1, a battery sensor 2, a BFT (battery fuse terminal) 3, a fuse box 4, a relay 5, a management ECU 10, load ECUs 11 to 13, loads 21 to 25, a power line 30, and a communication network 40. In FIG. 1, the thick lines correspond to the power line 30, and the dotted lines correspond to the communication network 40.

[0012] Battery 1 is a low-voltage power supply for operating loads 21 to 25 such as auxiliary equipment, management ECU 10, and load ECUs 11 to 13. Battery 1 is a battery of 60 volts or less, for example a 12 V battery, and is a secondary battery such as a lithium-ion battery or a lead battery. When power supply system 100 is installed in an electric vehicle or hybrid vehicle, the rated voltage of battery 1 is lower than the rated voltage of the vehicle's high-voltage battery.

[0013] A battery sensor 2 is connected to the battery 1. The battery sensor 2 measures the charging current or discharging current of the battery 1 and stores the measured value in a memory within the sensor. The battery sensor 2 measures the discharging current of the battery 1 while the vehicle is parked and the vehicle's main switch (ignition switch) is off. In other words, the battery sensor 2 measures the vehicle's dark current, which is discharged from the battery 1 at a predetermined cycle, even while the management ECU 10 and the load ECUs 11 to 13 are in a sleep state while the vehicle is parked. Note that the battery sensor 2 is not limited to measuring the current of the battery 1, and may also measure the voltage.

[0014] The BFT 3 is connected to the battery 1 and has a fuse with a high withstand voltage. The fuse box 4 branches the power line 30 connected to the battery 1 downstream of the BFT 3. The fuse box 4 has a plurality of fuses with a lower withstand voltage than the fuses included in the BFT 3. The fuses are connected to the branch of the power line 30. The management ECU 10, load ECUs 11 to 13, and loads 21 to 25 are connected to the power line 30 branched by the fuse box 4.

[0015] The relay 5 is connected to a power line 30 that runs from the fuse box 4 to the load 22, and switches on and off the current that flows from the battery 1 to the load ECU 12 and the load 22. The relay 5 is controlled by the management ECU 10. The relay may be a mechanical relay or a semiconductor switching element.

[0016] The management ECU 10 is an electronic control unit that manages the operating states of the load ECUs 11 to 13 connected to a communication network 40. The management ECU 10 transmits control signals to the load ECUs 11 to 13 via the communication network 40 to wake up or put the load ECUs 11 to 13 into sleep mode. The management ECU 10 also controls the vehicle's power sources, such as the ACC power source and the IGN power source. For example, the management ECU 10 turns on the relay 5 to turn on the vehicle's power source, i.e., the ACC power source. When the ACC power source is on, power from the battery 1 is supplied to the load ECU 12 and the load 22, making the load 22 operable. When the ACC power source is off, the relay 5 is off, making the load 22 inoperable. On the other hand, the load ECUs 11 and 13 and the loads 21 and 23 can operate using power from the battery 1 even when the ACC power source is off. When the IGN power source is on (corresponding to an ignition switch being on), the vehicle is ready to run.

[0017] The management ECU 10 is in a sleep state while the vehicle is parked and wakes up (enters an active state) at predetermined intervals (e.g., every few hours, such as every two hours). When the management ECU 10 wakes up, it diagnoses the operating state of the load ECUs 11 to 13 based on the vehicle's dark current (the discharge current of the battery 1). First, the management ECU 10 acquires measurement data stored in the memory of the battery sensor 2. The measurement data includes a measurement value of the discharge current of the battery 1. The management ECU 10 determines, based on the measurement value included in the measurement data, whether the discharge current of the battery 1 is equal to or greater than a predetermined dark current threshold. The dark current threshold is set to a value higher than the current value discharged when the vehicle is parked (unloaded). If the discharge current of the battery 1 is equal to or greater than the predetermined dark current threshold, the management ECU 10 determines that the operating state of the load ECUs 11 to 13 is abnormal and transmits a control signal to the load ECUs 11 to 13 to put the load ECUs 11 to 13 into sleep mode. On the other hand, if the discharge current of the battery 1 is less than the predetermined dark current threshold, the management ECU 10 determines that the load ECUs 11 to 13 are operating normally and goes into sleep mode.

[0018] Furthermore, before sending a control signal to put the load ECUs 11 to 13 to sleep, the management ECU 10 executes a sleep sequence to create an environment conducive to sleep, and then transmits the control signal to put the load ECUs 11 to 13 to sleep. The sleep sequence includes at least a flow for transmitting the control signal to put the load ECUs 11 to 13 to sleep. In other words, when the discharge current of the battery 1 is equal to or greater than the dark current threshold, the management ECU 10 puts the load ECUs 11 to 13 to sleep using the same sleep sequence as when the IGN power is switched from on to off.

[0019] Loads 24 and 25 are connected downstream of the management ECU 10, and the management ECU 10 controls the loads 24 and 25. The management ECU 10 is also connected to the load ECUs 11 to 13 via a communication network 40 so as to be able to communicate with them. The management ECU 10 transmits and receives signals to and from the load ECUs 11 to 13, and can obtain information indicating the operating state of the load 21 from the load ECU 11, for example. The management ECU 10 obtains power from the battery 1.

[0020] The load ECUs 11 to 13 are electronic control units that control the loads 21 to 23, and are respectively connected to branches of a power line 30 that connects from the fuse box 4 to the loads 21 to 23. The load ECUs 11 to 13 are connected to a communication network 40. The load ECUs 11 and 12 are also connected via the communication network 40 and can transmit and receive signals to and from each other. Therefore, the load ECUs 11 and 12 do not necessarily need to communicate via the management ECU 10, and the load ECU 11 can obtain information indicating the operating state of the load 22 through communication with the load ECU 12.

[0021] The loads 21 to 25 are in-vehicle devices. The loads 21, 23 to 25 can operate even when the ACC power is off. An example of the loads 21, 23 to 25 is an in-vehicle device included in a keyless entry system, such as a communicator that communicates with the surroundings of the vehicle while the vehicle is parked. The loads 21, 23 to 25 can operate as long as the management ECU 10 and the load ECUs 11 and 13 that control the loads 21, 23 to 25 are at least in a wake-up state. On the other hand, since the load 22 is connected to the relay 5, it can operate when the relay 5 is on (e.g., when the ACC power is on).

[0022] The power line 30 is a harness, a hard wire, etc. The communication network 40 is an in-vehicle communication network such as CAN or LIN. Note that the connection configuration of the power line 30 and the communication network 40 shown in FIG. 1 is merely an example, and the communication network 40 may be configured so that the load ECU 12 and the load ECU 13 can communicate with each other without going through the management ECU 10.

[0023] Next, a sleep failure of the load ECUs 11 to 13 will be described. The management ECU 10 and the load ECUs 11 to 13 enter sleep mode when predetermined sleep conditions are met. The sleep conditions include, for example, receiving a sleep frame or acquiring information necessary for sleep processing from the load ECUs 11 to 13. The sleep frame is included in a control signal transmitted to the load ECUs 11 to 13 in the sleep sequence. Furthermore, for example, the load ECU 11 acquires information indicating the operating state of the load 22 from the load ECU 12 and determines whether the sleep conditions are met based on the information about the load 22. The information indicating the operating state of the load 22 corresponds to the information necessary for sleep processing. In the following description, a failure of the load ECU 11 is used as an example.

[0024] When the vehicle's IGN power is switched from on to off and the manager ECU 10 executes a sleep sequence, the manager ECU 10 transmits a control signal including a sleep frame to the load ECUs 11 to 13. If the load ECU 11 fails to receive the sleep frame due to, for example, a temporary communication failure in the communication network 40, the sleep condition is not met, and the load ECU 11 enters a wake-up state and does not enter sleep mode (sleep failure). The load ECUs 12 and 13 successfully receive the sleep frame and enter sleep mode.

[0025] Furthermore, the load ECU 11 acquires information indicating the operating state of the load 22 from the load ECU 12 through communication with the load ECU 12, and if the sleep conditions are met based on the acquired information, the load ECU 11 goes into sleep mode. However, if for some reason the load ECU 11 cannot acquire information indicating the operating state of the load 22 from the load ECU 12, the sleep conditions are not met, and the load ECU 11 remains in a wake-up state and does not go into sleep mode (sleep failure).

[0026] If the above-described state in which the load ECU 11 does not enter sleep mode occurs while the vehicle is parked, the management ECU 10 and the load ECUs 12 and 13 other than the load ECU 11 enter sleep mode, consuming little power, but the load ECU 11 remains awake, consuming power from the battery 1. If the load ECU 11 fails to enter sleep mode, the discharge current of the battery 1 becomes higher than the vehicle's dark current threshold. That is, the management ECU 10 diagnoses, from the discharge current of the battery 1, an abnormal current consumption state of the load 21 due to the load ECU 11's sleep failure. The management ECU 10 then executes the sleep sequence described below.

[0027] The sleep sequence by the management ECU 10 will be described with reference to Figure 2. Figure 2 is a graph for explaining the relationship between the operating state and power state of the management ECU 10 and the load ECUs 11 to 13 and the number of functioning ECUs. "Sleep" indicates the sleep state of the management ECU 10 and the load ECUs 11 to 13, and the network of the communication network 40 is not activated (communication is not possible). "Wakeup" indicates the wake-up state of the management ECU 10 and the load ECUs 11 to 13, and the network of the communication network 40 is activated (communication is possible). "ACC" indicates the ACC power is on.

[0028] In the sleep sequence, all load ECUs 11 to 13 connected to the communication network 40 transition from a sleep or wake-up state to an ACC power-on state. That is, the ECU 10 forcibly wakes up all load ECUs 11 to 13 connected to the communication network 40, including the load ECUs 11 to 13 that have successfully entered sleep mode, and transitions the vehicle's power supply to an ACC power-on state. For example, due to a sleep failure, the ECU 10 or some of the load ECUs 11 to 13 transition from an operating state in which they are functioning without going into sleep mode to an ACC power-on state (corresponding to arrow a in FIG. 2). Also, due to a sleep failure, the ECU 10 or some of the load ECUs 11 to 13 transition from a state in which they are functioning without going into sleep mode and the number of functioning ECUs exceeds the number of functioning ECUs at wake-up mode to an ACC power-on state (corresponding to arrow b in FIG. 2).

[0029] In the sleep sequence, all load ECUs 11 to 13 connected to the communication network 40 transition from an ACC power-on state to a sleep state after a predetermined wake-up time has elapsed. The predetermined wake-up time may be as short as possible. In other words, the management ECU 10 forcibly puts the load ECUs 11 to 13, which have been woken up by turning on the ACC power, into sleep mode. When forcing the load ECUs 11 to 13 into sleep mode, the management ECU 10 transmits a control signal (a signal including a sleep frame) to put the load ECUs 11 to 13 into sleep mode, as in the normal sleep sequence, to all load ECUs 11 to 13 connected to the communication network 40. As a result, the load ECUs 11 to 13 that failed to enter sleep mode enter sleep mode, and the abnormal current consumption state of the loads 21 to 25 is resolved.

[0030] The sleep sequence by the management ECU 10 will be described with reference to Figure 3. Figure 2 is a graph for explaining the relationship between the operating state and power supply state of the management ECU 10 and the load ECUs 11 to 13 and the magnitude of current consumption in each state. Note that "Sleep," "Wakeup," and "ACC" are the same as in Figure 2. When the management ECU 10 and the load ECUs 11 to 13 are in sleep mode, the current consumption of the battery 1 is lowest. The current consumption when the management ECU 10 and the load ECUs 11 to 13 are in wakeup mode is the next highest, and the current consumption when the ACC power is on is the highest.

[0031] For example, if some ECUs fail to enter sleep mode due to a sleep failure, the current consumption may be higher than the current consumption when the management ECU 10 and the load ECUs 11-13 are in sleep mode. Furthermore, the current consumption during sleep failure may also be higher than the current consumption when the management ECU 10 and the load ECUs 11-13 are in wake-up mode. In this embodiment, the ECU 10 forcibly wakes up the load ECUs 11-13 and transitions the vehicle's power supply to an ACC power-on state. Therefore, the load ECUs 11-13 transition from their sleep-failure state to an ACC power-on state (corresponding to arrows a and b in FIG. 3 ). After waking up the load ECUs 11-13, the management ECU 10 executes a sleep sequence to force them into sleep mode. Note that, as shown in FIG. 3 , the ACC power-on state is very short. As a result, the load ECUs 11-13 that failed to enter sleep mode enter sleep mode, and the abnormal current consumption state of the loads 21-25 is resolved.

[0032] As described above, the power supply system 100 according to this embodiment includes the battery sensor 2 and the ECU 10. When the discharge current of the battery 1 measured by the battery sensor 2 is equal to or greater than a predetermined dark current threshold, the ECU 10 transmits a control signal to the load ECUs 11-13 to put them into sleep mode. This reduces power consumption during abnormality diagnosis. Since the components required for abnormality diagnosis are at least the battery sensor 2 and the ECU 10, current consumption during abnormality diagnosis can be reduced. The power supply system 100 also diagnoses the operating states of the management ECU 10 and the load ECUs 11-13 based on the discharge current of the battery 1. Therefore, even if a control signal to put the management ECU 10 and the load ECUs 11-13 into sleep mode is transmitted to the management ECU 10 and the load ECUs 11-13, and communication with the communication network 40 becomes unavailable, and a specific load ECU 11 continues waking up without entering sleep mode due to a sleep failure, the sleep failure can still be diagnosed based on the discharge current of the battery 1. In addition, in this embodiment, the management ECU 10 can determine the operating states of the load ECUs 11 to 13 without communicating with the other load ECUs 11 to 13. To maintain a communication network between the management ECU 10 and the load ECUs 11 to 13, other ECUs on the communication network must also operate, which increases overall power consumption. In this embodiment, there is no need to build a communication network to determine the operating states of the load ECUs 11 to 13, so power consumption can be reduced.

[0033] In this embodiment, when the discharge current of the battery 1 is equal to or greater than the dark current threshold, the ECU 10 transitions to the ACC power-on state and transmits a control signal from the ACC power-on state to put the load ECUs 11 to 13 into sleep mode, thereby forcing the load ECUs 11 to 13 in which a sleep failure has occurred to go into sleep mode.

[0034] In this embodiment, the ECU 10 executes a sleep sequence to put the load ECUs 11 to 13 into sleep mode when the vehicle's IGN power supply is switched from on to off, and executes the sleep sequence when the discharge current of the battery 1 is equal to or greater than the dark current threshold. In other words, when forcibly putting the load ECUs 11 to 13 into sleep mode after a sleep failure occurs, the ECU 10 uses the normal sleep sequence. This eliminates the need for additional circuits to execute the sleep sequence.

[0035] In this embodiment, the determination of whether the discharge current of the battery 1 is equal to or greater than the dark current threshold may be performed not only by the ECU 10 but also by the battery sensor 2. That is, the battery sensor 2 may have the functions of measuring the current of the battery 1, storing the measurement data, and determining whether the discharge current is abnormal. While the ECU 10 wakes up at a predetermined cycle to acquire measurement data from the battery sensor 2 while the vehicle is parked, this cycle of waking up is no longer necessary. The battery sensor 2 compares the measured discharge current with a dark current threshold, and if the discharge current is equal to or greater than the dark current threshold, transmits a control signal to the ECU 10 to wake up. The ECU 10 then wakes up and transmits a control signal to the load ECUs 11 to 13 to put them into sleep mode. That is, if the discharge current of the battery 1 measured by the battery sensor 2 is equal to or greater than the dark current threshold, the ECU 10 transmits a control signal to the load ECUs 11 to 13 to put them into sleep mode. This reduces power consumption during abnormality diagnosis.

[0036] As a modification of this embodiment, the ECU 10 may determine whether the discharge current of the battery 1 is equal to or greater than the dark current threshold while avoiding situations where erroneous determination is likely to occur. For example, the ECU 10 recognizes the operating states of the load ECUs 11 to 13 based on communication signals transmitted and received over the communication network 40, and if it determines that the operating states of the load ECUs 11 to 13 are not in a sleep state, it does not determine whether the discharge current is equal to or greater than the dark current threshold. If the ECU 10 can recognize the wake-up state of the load ECUs 11 to 13 from communication information included in the communication signals over the communication network 40, it is preferable that the ECU 10 does not determine whether the discharge current is an abnormal current.

[0037] Furthermore, for example, the ECU 10 recognizes the operating states of the load ECUs 11 to 13 based on the state of the power line 30, and when it recognizes that the operating state of the load ECUs 11 to 13 is not in a sleep state, it does not determine whether the discharge current is equal to or greater than the dark current threshold. If the current and voltage flowing through the power line 30 can be measured from other sensors included in the vehicle, the ECU 10 may recognize the operating states of the load ECUs 11 to 13 from the measured values ​​of the other sensors.

[0038] Furthermore, for example, the ECU 10 recognizes the operating states of the load ECUs 11 to 13 based on periodic transitions of the operating states of the load ECUs 11 to 13, and if it recognizes that the operating states of the load ECUs 11 to 13 are not in the sleep state, it does not determine whether the discharge current is equal to or greater than the dark current threshold. If a wake-up period during which the load ECUs 11 to 13 wake up from the sleep state is predetermined while the vehicle is parked, the operating states of the load ECUs 11 to 13 may be recognized from the wake-up period.

[0039] As a modification of this embodiment, the number of times the management ECU 10 resets the load ECUs 11 to 13 when the discharge current is equal to or greater than the dark current threshold may be limited to a predetermined number of times. The number of times the management ECU 10 resets the load ECUs 11 to 13 corresponds to the number of times the sleep sequence is executed. The sleep sequence forcibly wakes up the load ECUs 11 to 13 and then puts them to sleep, so the execution of the sequence consumes power from the battery 1. Therefore, an upper limit may be set to prevent excessive forced resets.

[0040] In this embodiment, the battery sensor 2 or the ECU 10 performs the abnormality diagnosis based on the current of the battery 1, but a voltage condition may also be added. That is, if the discharge current of the battery 1 is equal to or greater than a predetermined dark current threshold and the voltage of the battery 1 is equal to or less than a predetermined voltage threshold, the battery sensor 2 or the ECU 10 may diagnose that the operating state of the load ECUs 11 to 13 is abnormal.

[0041] As a modification of this embodiment, when the discharge current of the battery 1 is equal to or greater than the vehicle's dark current threshold, the management ECU 10 may turn on the IGN power supply and switch from the IGN power-on state to the ACC power-on state, thereby forcibly waking up the load ECUs 11 to 13. After forcibly waking up the load ECUs 11 to 13, the management ECU 10 may execute a sleep sequence.

[0042] The load ECUs 11 to 13 in this embodiment correspond to the "ECU" of the present invention.

[0043] REFERENCE SIGNS LIST 1 Battery 2 Battery sensor 3 BFT 4 Fuse box 5 Relay 10 Management ECU 11 to 13 Load ECUs 21 to 25 Load 30 Power line 40 Communication network 100 Power supply system

Claims

1. A power supply system installed in a vehicle equipped with a communication network and a battery, comprising: a battery sensor that measures the current of the battery; and a management ECU that controls the operating state of an ECU connected to the communication network, and when the discharge current of the battery measured by the battery sensor is equal to or greater than a predetermined dark current threshold, the management ECU sends a control signal to the ECU to put it into sleep mode.

2. A power supply system as claimed in claim 1, wherein, when the discharge current is equal to or greater than the dark current threshold, the management ECU transitions to an ACC power on state in which the battery's power can be supplied to a load, and transmits the control signal from the ACC power on state to put the ECU into sleep mode.

3. A power supply system as claimed in claim 1 or 2, wherein the management ECU executes a sleep sequence to put the ECU into sleep mode when the IGN power supply of the vehicle is switched from on to off, and executes the sleep sequence when the discharge current is equal to or greater than the dark current threshold.

4. A power supply system as claimed in claim 1 or 2, wherein the management ECU recognises the operating state of the ECU based on a communication signal transmitted and received over the communication network, and when it recognises that the operating state of the ECU is not a sleep state, does not determine whether the discharge current is equal to or greater than the dark current threshold.

5. A power supply system as claimed in claim 1 or 2, wherein the management ECU recognizes the operating state of the ECU based on the state of a power line connecting a load included in the vehicle and the battery, and when it recognizes that the operating state of the ECU is not a sleep state, does not determine whether the discharge current is equal to or greater than the dark current threshold.

6. A power supply system as claimed in claim 1 or 2, wherein the management ECU recognises the operating state of the ECU based on periodic transitions in the operating state of the ECU, and when it recognises that the operating state of the ECU is not a sleep state, does not determine whether the discharge current is equal to or greater than the dark current threshold.

7. A power supply system according to claim 1 or 2, wherein when the discharge current is equal to or greater than the dark current threshold, the number of resets of the ECU executed by the management ECU is equal to or less than a predetermined limit number of times.

8. A control method for a power supply system installed in a vehicle equipped with a communication network and a battery, comprising: obtaining a measured value of the discharge current of the battery from a battery sensor that measures the current of the battery; controlling the operating state of an ECU connected to the communication network; and sending a control signal to the ECU to put it into sleep mode if the discharge current of the battery measured by the battery sensor is equal to or greater than a predetermined dark current threshold.

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