Vehicle power system

Abstract

This invention provides a technology that enables more appropriate transmission of signals via a power line supplying power from a first control unit to a second control unit in a vehicle's power supply system. [Solution] The first control device 10 is connected to the power supply 14. The second control device 12 is connected to the first control device 10 via a power line 16 and operates on power supplied from the first control device 10 via the power line 16. A switch 28 switches between allowing conduction between the power supply 14 and the power line 16. A power supply unit 26 can supply power to the power line 16. When the switch 28 is in the conductive state, power is supplied from the power supply 14 to the power line 16 at a first voltage. When the switch 28 is in the non-conductive state, power is supplied from the power supply unit 26 to the power line 16 at a second voltage. The first control unit 30 transmits a pulse signal to the second control device 12 via the power line 16 by switching the switch 28.

Description

Technical Field

[0001] The present invention relates to a power supply system for a vehicle.

Background Art

[0002] Patent Document 1 discloses an in-vehicle communication system. This system includes a meter ECU disposed on an instrument panel that supplies a DC power source, a communication ECU disposed at a rear end of the vehicle, and a single transmission line connecting between the meter ECU and the communication ECU. The meter ECU includes means for converting the voltage of the DC power source into a voltage of a pulse-like train in accordance with a signal of a switch. The communication ECU includes means for monitoring the voltage of the pulse-like train.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology of Patent Document 1, the low level of the voltage of the pulse-like train is 0V, and the high level is 12V. Therefore, while the voltage of the pulse-like train is 0V, the power supply from the meter ECU to the communication ECU is cut off. While the power supply to the communication ECU is cut off, the communication ECU supplies power from a capacitor to a load lamp. However, when the capacitance of the capacitor is insufficient, the lighting of the lamp may become unstable. When the capacitance of the capacitor is increased, the system tends to be enlarged, and the product cost also tends to increase.

[0005] An object of the present invention is to provide a technique capable of more appropriately transmitting a signal via a power supply line that supplies power from a first control device to a second control device in a power supply system of a vehicle.

Means for Solving the Problems

[0006] To solve the above problems, a vehicle power supply system according to one aspect of the present invention comprises a first control device connected to a power source, and a second control device connected to the first control device via a power line and operating on power supplied from the first control device via the power line. The first control device includes a switch for switching between conducting or not conducting between the power source and the power line, a first control unit for controlling the switch, and a power supply unit capable of supplying power to the power line. When the switch is in a conducting state, power is supplied from the power source to the power line at a first voltage. When the switch is in a non-conducting state, power is supplied from the power supply unit to the power line at a second voltage different from the first voltage. The first control unit transmits a pulse signal to the second control device via the power line by switching the switch. The second control device has a second control unit that determines the control content based on the pulse signal received via the power line. [Effects of the Invention]

[0007] According to the present invention, a technology is available that enables more appropriate transmission of signals via a power line supplying power from a first control device to a second control device in a vehicle's power supply system. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows the configuration of the power supply system of the vehicle according to the embodiment. [Figure 2] Figures 2(a) and 2(b) show examples of pulse signals. [Figure 3] This is a diagram illustrating the transitions between operating modes. [Figure 4] Figure 1 is a flowchart showing the operation of the first control device. [Figure 5] This is a flowchart showing the operation of the second control device in Figure 1. [Modes for carrying out the invention]

[0009] Figure 1 schematically shows the configuration of the power supply system 1 of the vehicle according to the embodiment. The power supply system 1 is mounted on a vehicle (not shown) and supplies power to various electrical loads. The vehicle may be a vehicle that uses only an internal combustion engine as the driving force source, or it may be an electric vehicle that uses an electric motor as the driving force source. Examples of electric vehicles include electric vehicles (BEV: Battery Electric Vehicle), hybrid vehicles (HEV: Hybrid Electric Vehicle), plug-in hybrid vehicles (PHEV: Plug-in Hybrid Electric Vehicle), or fuel cell vehicles (FCEV: Fuel Cell Electric Vehicle). The vehicle may be a vehicle driven by a driver, or it may be an autonomous vehicle.

[0010] As shown in Figure 1, the power supply system 1 comprises a first control device 10, a second control device 12, a power supply 14, and a power line 16. The first control device 10 and the second control device 12 can each be configured as an ECU (Electronic Control Unit).

[0011] The first control device 10 is connected to a DC power supply 14 via a power supply terminal 32. The power supply 14 is, for example, the vehicle's auxiliary battery. The voltage of the power supply 14 is denoted as the first voltage V1. The first voltage V1 is, for example, about 13.5V.

[0012] The second control device 12 is connected to the first control device 10 via a power line 16 and operates using power supplied from the first control device 10 via the power line 16.

[0013] The second control device 12 can control whether or not to supply power to a vehicle load (not shown) connected to the output terminal 66. The load may include, for example, various lamps such as headlamps, surrounding surveillance cameras, various ECUs, etc. The load operates using the power supplied from the first control device 10 via the second control device 12.

[0014] The first control device 10 includes an input circuit 20, a communication circuit 22, a regulator 24, a power supply unit 26, a switch 28, and a first control unit 30.

[0015] The input circuit 20 is connected to an ignition switch (not shown) of the vehicle or the like via a switch input terminal 34. The input circuit 20 can also be called a switch input interface circuit. The input circuit 20 receives an input of a signal indicating whether the ignition switch is on or off, and supplies switch information indicating whether the ignition switch is on or off to the first control unit 30.

[0016] The communication circuit 22 is connected to another ECU or microcomputer of the vehicle via a communication input terminal 36. The communication circuit 22 can also be called a communication interface circuit. The communication circuit 22 receives an input of a control signal from another ECU or microcomputer, and supplies control information specified from the control signal to the first control unit 30.

[0017] The regulator 24 receives a first voltage V1 from a power source 14 via a power supply terminal 32, adjusts the first voltage V1 to a predetermined power supply voltage, and supplies the adjusted power supply voltage to the first control unit 30.

[0018] The power supply unit 26 receives power from the power source 14 via the power supply terminal 32, and can supply power to a power line 16 via an output terminal 38 based on the received power. The power supply unit 26 can also be called a constant power supply.

[0019] The power supply unit 26 includes a DC / DC converter 40 and a diode D1. The DC / DC converter 40 steps down the first voltage V1 supplied from the power source 14.

[0020] Diode D1 has an anode to which the voltage stepped down by the DC / DC converter 40 is supplied, and a cathode connected to one end of the power line 16 via the output terminal 38. The cathode of diode D1 outputs the second voltage V2 when the switch 28 is in the non-conductive state. The second voltage V2 is lower than the first voltage V1 and is, for example, 10V. The second voltage V2 is preset to a voltage at which the second control device 12 and the load can operate.

[0021] The switch 28 switches whether to conduct between the power supply 14 and the power line 16. The switch 28 is, for example, a semiconductor relay or a semiconductor switch. The switch 28 has one end to which the first voltage V1 is supplied from the power supply 14 via the power supply terminal 32, the other end connected to one end of the power line 16 via the output terminal 38, and a control terminal to which a control signal is supplied from the first control unit 30. That is, the cathode of the diode D1 and the other end of the switch 28 are commonly connected to the output terminal 38.

[0022] When the switch 28 is in the conductive state, power is supplied from the power supply 14 to the power line 16 at the first voltage V1 through the switch 28. When the switch 28 is in the conductive state, no power is supplied from the power supply unit 26 to the power line 16. On the other hand, when the switch 28 is in the non-conductive state, power is supplied from the power supply unit 26 to the power line 16 at the second voltage V2.

[0023] Therefore, the voltage of the power line 16 changes to the first voltage V1 or the second voltage V2 according to whether the switch 28 is in the conductive state. Regardless of whether the switch 28 is in the conductive state, the first control device 10 can supply power at which the second control device 12 and the load can operate to the second control device 12.

[0024] The first control unit 30 controls the switch 28. In a predetermined case, the first control unit 30 generates a pulse signal S1 by switching the switch 28 between a conductive state and a non-conductive state, and transmits the generated pulse signal S1 to the second control device 12 via the power line 16. The high level of the pulse signal S1 is the first voltage V1, and the low level of the pulse signal S1 is the second voltage V2. The pulse signal S1 is, for example, a PWM (Pulse Width Modulation) signal. It can also be said that the first control unit 30 superimposes the pulse signal S1 onto the power line 16. The first control unit 30 can be configured as, for example, a microcontroller.

[0025] The first control unit 30 determines whether predetermined conditions for changing the operating mode have been met, based on the switch information supplied from the input circuit 20 and the control information supplied from the communication circuit 22.

[0026] The operating modes include, for example, Mode 1, Mode 2, and Mode 3. Mode 1 is the operating mode when the ignition switch is off. Mode 1 is a low-power mode selected when the vehicle is parked. In Mode 1, the vehicle's power state is powered off.

[0027] The second mode is the operating mode when the ignition switch is ON. The second mode is the mode in which normal control is performed, such as when the vehicle is in motion. In the second mode, the vehicle's power state is IG ON.

[0028] The third mode is used when the ignition switch is off and intermittent operation is instructed. The third mode is selected when the vehicle is parked. The third mode is a low-power mode, but it operates the load periodically.

[0029] Details of each mode will be described later. More operating modes may be provided.

[0030] The conditions for changing the operating mode are met, for example, when the ignition switch is turned from off to on, when the ignition switch is turned from on to off, or when intermittent operation is instructed by control information while the ignition switch is off.

[0031] The first control unit 30 keeps the switch 28 in a conductive state if the conditions for changing the operating mode are not met. In this case, the pulse signal S1 is not transmitted, and the normal power supply to the second control unit 12 continues.

[0032] When the conditions for changing the operating mode are met, the first control unit 30 transmits a pulse signal S1 with a duty cycle pre-associated with the changed operating mode for a predetermined transmission period, and then controls the switch 28 to a conductive state. The frequency and transmission period of the pulse signal S1 can be appropriately determined by experiment or simulation. For example, the pulse signal S1 may contain several pulses to about 10 pulses during the transmission period.

[0033] The frequency of the pulse signal S1 may be, for example, several kHz. A low-pass filter may be provided between the connection node between the other end of switch 28 and the cathode of diode D1 and the output terminal 38. This can improve the signal-to-noise ratio of the pulse signal S1.

[0034] For example, the first mode is associated with a 0% duty cycle. The second mode is associated with a 100% duty cycle. The third mode is associated with a 50% duty cycle. The duty cycles for each mode may differ by, for example, 10%.

[0035] Figures 2(a) and 2(b) show examples of the pulse signal S1 in Figure 1. Figure 2(a) shows the pulse signal S1 with a duty cycle of 50%. Figure 2(b) shows the pulse signal S1 with a duty cycle of 100%. In this example, the duty cycle is the on-duty cycle. The period from time t1 to time t2 is the transmission period.

[0036] As shown in Figure 2(a), during the period when the switch is in a non-conductive state during the transmission period, a second voltage V2 is supplied from the power supply unit 26 to the power line 16, so that the second control device 12 and the load can operate stably even during the transmission period.

[0037] Returning to Figure 1, the second control device 12 includes an input circuit 50, a detection unit 52, a regulator 54, a switch 56, and a second control unit 58.

[0038] The input circuit 50 is connected to a user-operable switch (not shown) via a switch input terminal 64. This switch is located inside the vehicle and is used to control the operation of a load. The input circuit 50 can also be called a switch input interface circuit. The input circuit 50 receives, for example, a signal indicating whether the switch is on or off, and supplies switch information indicating whether the switch is on or off to the second control unit 58.

[0039] The detection unit 52 detects the pulse signal S1 received via the power line 16 and power terminal 62, and supplies a signal indicating the detection result to the second control unit 58. The detection unit 52 includes a Zener diode D2, a first resistor R1, a second resistor R2, a transistor T1, and a third resistor R3.

[0040] The Zener diode D2 has a cathode connected to the other end of the power line 16 via the power terminal 62, and an anode.

[0041] The first resistor R1 and the second resistor R2 are connected in series between the anode of the Zener diode D2 and ground.

[0042] Transistor T1 has a control terminal connected to the connection nodes of the first resistor R1 and the second resistor R2, a grounded first terminal, and a second terminal that outputs a signal indicating the detection result to the second control unit 58.

[0043] The third resistor R3 has one end to which the third voltage V3 is supplied, and the other end connected to the second terminal of transistor T1.

[0044] When the pulse signal S1 is at a low level, that is, when the second voltage V2 is supplied to the power supply terminal 62, transistor T1 is in a non-conducting state, and transistor T1 outputs a third voltage V3 as a signal indicating the detection result.

[0045] On the other hand, when the pulse signal S1 is at a high level, that is, when the first voltage V1 is supplied to the power supply terminal 62, the transistor T1 is in a conducting state, and the transistor T1 outputs a voltage lower than the third voltage V3 as a signal indicating the detection result.

[0046] With this circuit configuration, the detection unit 52 can detect the pulse signal S1 superimposed on the power line 16.

[0047] The regulator 54 adjusts the first voltage V1 or the second voltage V2 of the power line 16 to a predetermined third voltage V3. The third voltage V3 is lower than the second voltage V2.

[0048] Switch 56 switches between enabling or disabling conductivity between the power supply terminal 62 and the output terminal 66. Switch 56 is, for example, a semiconductor relay or a semiconductor switch. Switch 56 has one end to which a first voltage V1 or a second voltage V2 is supplied via the power supply terminal 62, the other end connected to the output terminal 66, and a control terminal to which a control signal is supplied from the second control unit 58.

[0049] When switch 56 is in a conductive state, power supplied from power line 16 is supplied to the load via switch 56. When switch 56 is in a non-conductive state, the power supply to the load is cut off.

[0050] The second control unit 58 operates using the third voltage V3 as the power supply voltage and determines the control content based on the pulse signal S1 received via the power line 16. The second control unit 58 executes control according to the detection result from the detection unit 52. From the detection result from the detection unit 52, the second control unit 58 identifies the duty cycle of the pulse signal S1, identifies the operating mode from the identified duty cycle, and executes control according to the identified operating mode. The second control unit 58 can be configured as, for example, a microcontroller.

[0051] Figure 3 is a diagram illustrating the transitions between operating modes. In the first mode, the first control unit 30 monitors the switch information of the trigger input circuit 20 and the control information of the communication circuit 22, while the second control unit 58 monitors the signal indicating the detection result from the detection unit 52.

[0052] In the second mode, the load can be operated and fully perform its function. In the second mode, the second control unit 58 monitors the switch information of the input circuit 50 and controls the switch 56 to a conductive or non-conductive state according to the switch information, thereby controlling the operation of the load.

[0053] In the third mode, the second control unit 58 intermittently supplies power to the load by intermittently switching the switch 56 from a non-conductive state to a conductive state, thereby causing the load to operate intermittently. For example, the second control unit 58 periodically operates a peripheral surveillance camera, which is the load.

[0054] As shown by the solid arrows in Figure 3, it is possible to transition from the first mode to the second mode, and from the second mode to the first mode. Furthermore, it is possible to transition from the first mode to the third mode, and from the third mode to the first mode.

[0055] When the system switches to the second mode while operating in the first mode, a pulse signal S1 with a 100% duty cycle is supplied to the second control device 12 when the first voltage V1 is supplied to the second control device 12. In order for the detection unit 52 to detect the pulse signal S1 with a 100% duty cycle, when the system switches to the second mode while operating in the first mode, the first control unit 30 may transmit the second voltage V2 for a predetermined time shorter than the transmission period before transmitting the pulse signal S1 over the transmission period. The detection unit 52 can detect the second voltage V2 for the predetermined time and then detect the pulse signal S1 with a 100% duty cycle over the transmission period. In other words, the detection unit 52 can detect the starting point of the pulse signal S1.

[0056] Furthermore, if the load connected to the output terminal 66 of the second control device 12 is a load that supplies a constant current to an LED or the like using a constant current circuit, the transition between the second mode and the third mode may be made directly, as shown by the dashed arrow in Figure 3. This is because even if the voltage supplied to the switch 56 via the power supply terminal 62 fluctuates between the first voltage V1 and the second voltage V2 during the transmission of the pulse signal S1, and the voltage supplied to the load from the output terminal 66 fluctuates similarly, it does not substantially affect the operation of the load.

[0057] Figure 4 is a flowchart showing the operation of the first control device 10 in Figure 1. The process in Figure 4 begins, for example, when a power supply 14 is connected to the power terminal 32 of the first control device 10 at a vehicle manufacturing plant or maintenance factory, and power is supplied from the power supply 14 to the first control device 10.

[0058] The first control unit 30 supplies power with the second voltage V2 by controlling the switch 28 to a non-conductive state (S10). The first control unit 30 determines whether to change the operating mode (S12). If the operating mode is not changed (N in S12), the process returns to S12. If the operating mode is changed (Y in S12), the first control unit 30 determines the duty cycle according to the changed operating mode (S14) and transmits the PWM signal for the transmission period (S16). The first control unit 30 supplies power with the first voltage V1 by controlling the switch 28 to a conductive state (S18), and the process returns to S12.

[0059] Figure 5 is a flowchart showing the operation of the second control device 12 in Figure 1. The process in Figure 5 starts when the process in Figure 4 begins and is executed in parallel with the process in Figure 4.

[0060] The second control unit 12 receives the second voltage V2 supplied in S10 of Figure 4 (S20). The second control unit 58 sets the operating mode to the first mode (S22) and determines whether a PWM signal has been received (S24). If a PWM signal has not been received (N in S24), the process returns to S24. If a PWM signal has been received (Y in S24), the second control unit 58 identifies the operating mode based on the PWM signal (S26) and transitions the operating mode (S28). The second control unit 12 receives the first voltage V1 supplied in S18 of Figure 4 (S30), and the process returns to S24.

[0061] In addition, in S10 of Figure 4, the first control unit 30 may be powered by the first voltage V1. In this case, in S20 of Figure 5, the second control device 12 receives the first voltage V1.

[0062] According to this embodiment, the pulse signal S1 can be transmitted from the first control device 10 to the second control device 12 via the same power line 16 without interrupting the power supply from the first control device 10 to the second control device 12 via the power line 16. Therefore, the pulse signal S1 can be transmitted more appropriately via the power line 16.

[0063] Furthermore, the dedicated wires for transmitting the pulse signal S1 can be reduced. In addition, the power supply system 1 does not require a separate dedicated communication IC and can be implemented with a simple circuit configuration. Therefore, the cost of the power supply system 1 can also be reduced.

[0064] The present invention has been described above based on embodiments. The embodiments are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of each component and each processing process, and that such modifications also fall within the scope of the present invention.

[0065] For example, the pulse signal S1 may be a signal with a fixed pulse width. In this case, for example, the high level of the pulse signal S1 may represent "1" and the low level may represent "0", and the pulse signal S1 may represent a digital signal. This modification improves the degree of freedom in the configuration of the power supply system 1. [Explanation of Symbols]

[0066] 1...Power supply system, 10...First control unit, 12...Second control unit, 14...Power supply, 16...Power line, 24...Regulator, 26...Power supply unit, 28...Switch, 30...First control unit, 40...DC / DC converter, 52...Detection unit, 54...Regulator, 56...Switch, 58...Second control unit, D1...Diode, D2...Zener diode, R1...First resistor, R2...Second resistor, R3...Third resistor, T1...Transistor.

Claims

1. A first control device connected to a power supply, A second control device is connected to the first control device via a power line and operates using power supplied from the first control device via the power line, Equipped with, The first control device is A switch for switching between enabling or disabling electrical conductivity between the power supply and the power line, A first control unit that controls the switch, A power supply unit capable of supplying power to the aforementioned power line, It has, When the switch is in a conductive state, power is supplied from the power supply to the power line at a first voltage. When the switch is in a non-conductive state, power is supplied from the power supply unit to the power line at a second voltage different from the first voltage. The first control unit transmits a pulse signal to the second control unit via the power line by switching the switch. The second control device has a second control unit that determines the control content based on the pulse signal received via the power line. A vehicle power supply system characterized by the following features.

2. The aforementioned pulse signal is a PWM signal. The vehicle power supply system according to feature 1.

3. The second control unit performs control according to the operating mode, When the conditions for changing the operating mode are met, the first control unit transmits the pulse signal with a duty cycle pre-associated with the changed operating mode over the transmission period, and then controls the switch to a conductive state. The vehicle power supply system according to feature 2.

4. The aforementioned power supply unit is A DC / DC converter that steps down the first voltage supplied from the power supply, A diode having an anode to which the voltage stepped down by the DC / DC converter is supplied, and a cathode connected to the power line to output the second voltage, A vehicle power supply system according to any one of claims 1 to 3, characterized by having the following features.

5. The second control device is A detection unit for detecting the pulse signal received via the power line, A regulator that adjusts the voltage of the power line to a third voltage, It has, The second control unit operates using the third voltage as the power supply voltage and performs control according to the detection result from the detection unit. The detection unit is A Zener diode having a cathode connected to the power line, A first resistor and a second resistor are connected in series between the anode of the Zener diode and ground, A transistor having a control terminal connected to the connection nodes of the first and second resistors, a grounded first terminal, and a second terminal that outputs a signal indicating the detection result to the control unit, A third resistor having one end to which the third voltage is supplied and the other end connected to the second terminal, A vehicle power supply system according to any one of claims 1 to 3, characterized by having the following features.

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