Vehicle power supply control method

Abstract

In a power supply system where the power from the main power supply and the power from a redundant power supply are supplied to an electronic control unit via the same relay, a vehicle power supply control method is provided that allows for diagnosis of relay stuck on without resetting the electronic control unit. [Solution] A vehicle power control method performed by a power supply system comprising a main power supply that supplies power to an electronic control unit mounted on a vehicle via a relay, and a redundant power supply that supplies backup power to the electronic control unit via a relay in the event of a failure of the main power supply, the method comprising: a first step of stopping the power supply from the main power supply to the electronic control unit after the vehicle ignition is turned off; and a second step of performing an ON-fixed diagnosis of the relay within the reset determination time of the electronic control unit after stopping the power supply in the first step.

Description

Technical Field

[0001] The present disclosure relates to a power control method executed by a power supply system including a main power supply and a redundant power supply that supply power to an electronic control unit mounted on a vehicle.

Background Art

[0002] Patent Document 1 discloses a vehicle power supply device that can continue to supply power to important loads even when an abnormality occurs in the power supply system. This vehicle power supply device includes a first path for supplying power from a first power supply (such as a main power supply) to important loads, and a second path for supplying power from a second power supply (such as a redundant power supply) to important loads via a switch (such as a relay). When diagnosing an on-stuck of the switch, it is described that the on-stuck diagnosis of the switch in the second path is performed while supplying power to the important load in the first path.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Due to reasons such as limitations in mounting space and cost reduction in vehicles, it is conceivable to adopt a power supply system in which power is supplied to an electronic control unit, which is an important load, through the same relay by a main power supply and a redundant power supply. However, when performing an on-stuck diagnosis of the relay in a power supply system with such a configuration, the power supply to the electronic control unit is temporarily interrupted (current off), so there is a risk that the electronic control unit will be reset due to a voltage drop.

[0005] This disclosure has been made in view of the above-mentioned problems, and aims to provide a vehicle power control method that can diagnose the ON-fixation of a relay without resetting the electronic control unit in a power supply system in which the power of the main power supply and the power of a redundant power supply are supplied to the electronic control unit via the same relay. [Means for solving the problem]

[0006] To solve the above problems, one aspect of the disclosed technology is a vehicle power control method performed by a power supply system comprising a main power supply that supplies power to an electronic control unit mounted on a vehicle via a relay, and a redundant power supply that supplies backup power to the electronic control unit via a relay in the event of a failure of the main power supply, the method comprising: a first step of stopping the power supply from the main power supply to the electronic control unit after the vehicle ignition is turned off; and a second step of performing a relay ON-fixed diagnosis within the reset determination time of the electronic control unit after stopping the power supply in the first step. [Effects of the Invention]

[0007] According to the vehicle power control method described above, the diagnostic process is completed within the reset determination time of the electronic control unit, so the relay being stuck in the ON position can be diagnosed without resetting the electronic control unit. [Brief explanation of the drawing]

[0008] [Figure 1] Schematic diagram of a power supply system that implements a vehicle power supply control method according to one embodiment of the present disclosure. [Figure 2] Sequence of relay-on lock-up diagnostic controls performed by the redundant power supply system after ignition off. [Modes for carrying out the invention]

[0009] The vehicle power supply control method disclosed herein controls the power supply without resetting the electronic control unit (SBW-ECU) by controlling existing PWM communication between the shift-by-wire (SBW) and the redundant power supply system. After receiving sleep permission for the electronic control unit via PWM communication from the shift-by-wire, a relay on-stick diagnosis is performed during the time when the ECU does not make a reset determination, thereby enabling power supply control on the same power supply line (1 system) without resetting the electronic control unit. Hereinafter, one embodiment of this disclosure will be described in detail with reference to the drawings.

[0010] <Embodiment> [composition] Figure 1 is a diagram showing a schematic configuration of a power supply system 100 that implements a vehicle power supply control method according to one embodiment of the present disclosure. The power supply system 100 illustrated in Figure 1 includes a main power supply 110 and a redundant power supply system 120. The redundant power supply system 120 is connected to a shift-by-wire (SBW) 200. The main power supply 110, the redundant power supply system 120, and the shift-by-wire (SBW) 200 are mounted on a vehicle or the like.

[0011] The main power supply 110 is a power source (main power supply) composed of a rechargeable secondary battery (such as a lithium-ion battery). This main power supply 110 is a primary power supply that supplies power at a predetermined voltage (+B voltage) to the shift-by-wire (SBW) 200.

[0012] The redundant power supply system 120 is a unit that functions as an auxiliary power supply to provide backup power to the shift-by-wire (SBW) 200 when an abnormality occurs in the power supply from the main power supply 110 to the shift-by-wire (SBW) 200 due to a power failure (such as voltage loss) of the main power supply 110. This redundant power supply system 120 includes a pass-through function unit 121, a first relay 122, a second relay 123, a redundant power supply 124, a DC-DC converter 125, and a control unit 126.

[0013] The pass-through function unit 121 is connected to the main power supply 110 and is configured to supply power from the main power supply 110 to the shift-by-wire (SBW) 200. This pass-through function unit 121 typically includes a switching element such as a semiconductor relay and switches the electrical connection state between the main power supply 110 and the shift-by-wire (SBW) 200 by controlling the conduction / contraction of the switching element based on instructions from the control unit 126.

[0014] The first relay 122 and the second relay 123 are composed of semiconductor relays or the like and are inserted between the connection point between the pass-through function unit 121 and the DC-DC converter 125 and the shift-by-wire (SBW) 200. Based on instructions from the control unit 126, the first relay 122 and the second relay 123 are controlled to be in a conduction state when power supply from the main power supply 110 or redundant power supply 124 to the shift-by-wire (SBW) 200 is required, and to be controlled to be in an interrupted state at other times. In this embodiment, the relay that is subject to on-fixation diagnosis is the second relay 123, which is connected to the SBW-ECU 220 described later.

[0015] The redundant power supply 124 is an auxiliary power source (sub-power supply) composed of, for example, an energy storage element such as a capacitor or a secondary battery such as a lithium-ion battery. This redundant power supply 124 is connected to the DC-DC converter 125 so that it can charge power input from the main power supply 110 via the pass-through function unit 121, and can discharge its own stored power (backup power) to the shift-by-wire (SBW) 200.

[0016] The DC-DC converter 125 is a power converter for controlling the charging and discharging of the redundant power supply 124. Based on instructions from the control unit 126, the DC-DC converter 125 can convert the power input from the main power supply 110 via the pass-through function unit 121 into power of a predetermined voltage and output it to the redundant power supply 124, or convert the power stored in the redundant power supply 124 into power of a predetermined voltage and output it to the shift-by-wire (SBW) 200.

[0017] The control unit 126 is configured to control the operations of the pass-through function unit 121, the first relay 122, the second relay 123, and the DC-DC converter 125 to realize power supply to the shift-by-wire (SBW) 200 via the redundant power supply system 120. The control unit 126 in this embodiment performs a relay on-fixation diagnosis for determining whether or not an abnormality occurs in which the second relay 123 is fixed in the conduction (ON) state based on an IGR signal indicating the ignition state of the vehicle. A microcomputer or the like is used for this control unit 126.

[0018] The shift-by-wire (SBW) 200 is a control system that can change the gear stage of a transmission (not shown) by an electric signal. The SBW 200 includes an SBW-ACT 210 and an SBW-ECU 220.

[0019] The SBW-ECU 220 is an electronic control unit that converts the driver's shift operation into an electric signal. The SBW-ECU 220 is connected to the pass-through function unit 121 and the DC-DC converter 125 via the second relay 123. The SBW-ACT 210 is an actuator that changes the gear stage based on an electric signal instructed from the SBW-ECU 220. The SBW-ACT 210 is connected to the pass-through function unit 121 and the DC-DC converter 125 via the first relay 122.

[0020] When the main power supply 110 is normal, the SBW-ACT 210 and the SBW-ECU 220 operate with the power (+B pass-through power) supplied from the main power supply 110 via the pass-through function unit 121, the first relay 122, and the second relay 123 of the redundant power supply system 120 (during normal control). Also, when the main power supply 110 fails, the SBW-ACT 210 and the SBW-ECU 220 operate with the power supplied from the redundant power supply 124 via the DC-DC converter 125, the first relay 122, and the second relay 123 (during backup control).

[0021] [Control] Next, referring further to FIG. 2, a vehicle power control method according to the present embodiment executed by the power supply system 100 will be described. FIG. 2 is a sequence for explaining the relay on-stuck diagnosis control (steps S22 to S26) executed by the redundant power supply system 120 when the main power supply 110 is normal without any faults and the ignition of the vehicle is in the off state (IGR-OFF) (step S11).

[0022] During the period when the ignition of the vehicle is in the on state (IGR-ON), which is the initial state before the relay on-stuck diagnosis control is implemented, the first relay 122 and the second relay 123 are in the conducting state, and power is supplied from the main power supply 110 to the SBW-ACT210 and the SBW-ECU220 (step S20).

[0023] When the ignition of the vehicle is switched from the on state to the off state (IGR-OFF), the redundant power supply system 120 notifies the SBW-ECU220 that the ignition has been turned off (step S11). This notification is made by the redundant power supply system 120 transmitting an IGR-OFF signal to the SBW-ECU220 by PWM communication.

[0024] The SBW-ECU220 that has received the IGR-OFF signal from the redundant power supply system 120 transmits a request to the redundant power supply system 120 to permit itself to shift from the wake-up state to the sleep state (step S31). This transmission is made by the SBW-ECU220 transmitting a predetermined sleep permission request signal to the redundant power supply system 120 by PWM communication.

[0025] Upon receiving a sleep permission request signal from the SBW-ECU220, the redundant power supply system 120 stops supplying power from the main power supply 110 to the SBW-ECU220 (step S22). This stop is achieved by the redundant power supply system 120 controlling the second relay 123 to an off state. Power supply from the main power supply 110 to the SBW-ACT210 continues. From the moment this power supply is stopped, the reset determination time in the SBW-ECU220 begins to progress.

[0026] When the power supply to the SBW-ECU220 is cut off, the redundant power supply system 120 performs an ON-fixed diagnosis of the second relay 123 (step S23). A well-known method can be used for this ON-fixed diagnosis.

[0027] Once the ON-lock diagnosis of the second relay 123 is complete, the redundant power supply system 120 determines whether the second relay 123 is ON-locked or not (step S24). If it is determined that the second relay 123 is ON-locked (step S24, yes), the system proceeds to step S25. If it is determined that the second relay 123 is not ON-locked (step S24, no), the system proceeds to step S26.

[0028] If the redundant power supply system 120 determines that the second relay 123 is stuck in the ON position, it records the determination result as "relay stuck in ON position" (step S25). An example of a location to record the determination result is the memory of the redundant power supply system 120 (not shown).

[0029] Once the ON-fixation diagnosis of the second relay 123 and the necessary recording are completed, the redundant power supply system 120 resumes supplying power from the main power supply 110 to the SBW-ECU 220 (step S26). This completes the relay ON-fixation diagnosis control. In this embodiment, the entire process from the start (step S22) to the completion (step S26) of this relay ON-fixation diagnosis control is performed within the reset determination time of the SBW-ECU 220 (the period during which the reset determination is not finalized). That is, the current-off time required to determine the ON-fixation of the relay 123 is set within the reset determination time range of the SBW-ECU 220.

[0030] The redundant power supply system 120, which has resumed supplying power from the main power supply 110 to the SBW-ECU220, stops communication with the SBW-ECU220 and transitions itself from the wake-up state to the sleep state (step S27). This cessation of communication is achieved by stopping (interrupting) communication with the SBW-ECU220 via PWM communication.

[0031] When communication with the redundant power supply system 120 is stopped (interrupted), the SBW-ECU220 transitions itself from the wake-up state to the sleep state (step S32).

[0032] These processes allow for diagnosis of the second relay 123 being stuck in the ON position without resetting the SBW-ECU220. Furthermore, by performing the diagnosis of the second relay 123 being stuck in the ON position after the ignition is turned off (IGR-OFF) and the vehicle has stopped, even if the SBW-ECU220 is reset during the diagnosis, the safety of the occupants can be ensured because the vehicle is stationary.

[0033] <Effects and Actions> As described above, according to a vehicle power control method according to one embodiment of the present disclosure, in a power supply system 100 comprising a main power supply 110 that supplies power to a shift-by-wire (SBW) 200 via a first relay 122 and a second relay 123, and a redundant power supply 124 that supplies backup power to the shift-by-wire (SBW) 200 via the first relay 122 and the second relay 123 when the main power supply 110 fails, the power supply from the main power supply 110 to the SBW-ECU 220 is stopped after the vehicle ignition is turned off (IGR-OFF), and thereafter an ON-fixed diagnosis of the second relay 123 is performed within the reset determination time of the SBW-ECU 220.

[0034] This control allows for the diagnosis of the second relay 123 being stuck in the ON position without resetting the SBW-ECU220, even if the power supply line from the main power supply 110 and redundant power supply 124 to the SBW-ECU220 is configured to be only one line (passing through the same second relay 123).

[0035] Although one embodiment of the disclosed technology has been described above, the disclosed technology can be understood not only as a vehicle power supply control method, but also as a program for the vehicle power supply control method, a computer-readable non-temporary storage medium storing the program, and a vehicle equipped with a power supply system that performs the vehicle power supply control method. [Industrial applicability]

[0036] The vehicle power control method disclosed herein can be used in vehicles that require backup power supply from a sub-power source to the vehicle load in the event of a main power failure. [Explanation of Symbols]

[0037] 100 Power Systems 110 Main power supply 120 Redundant Power Supply Systems 121 Pass-through function section 122, 123 Relay 124 Redundant power supply 125 DC-DC Converter 126 Control Unit 200 Shift-by-wire (SBW) 210 SBW-ACT 220 SBW-ECU

Claims

1. A vehicle power control method performed by a power supply system comprising a main power supply that supplies power to an electronic control unit mounted on a vehicle via a relay, and a redundant power supply that supplies backup power to the electronic control unit via the relay when the main power supply fails, The first step is to stop the power supply from the main power source to the electronic control unit after the ignition of the vehicle has been turned off, The second step includes, after stopping the power supply in the first step, performing an ON-fixed diagnosis of the relay within the reset determination time of the electronic control unit, Vehicle power supply control method.

2. The first step is initiated when the power supply system receives a sleep permission request signal from the electronic control unit, which has detected the ignition being turned off. The vehicle power supply control method according to claim 1.

3. The second step involves performing a diagnosis of whether the relay is stuck on, by setting the current off time required to determine whether the relay is stuck on to within the reset determination time. The vehicle power supply control method according to claim 1 or 2.

4. The aforementioned electronic control unit is an SBW-ECU that controls shift-by-wire. A vehicle power supply control method according to any one of claims 1 to 3.

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