Power supply system for vehicle

Abstract

The invention relates to a power supply system of a vehicle. A first control device of the vehicle power supply system is connected to a power supply. The second control device is connected to the first control device via a power line, and operates by power supplied from the first control device via the power line. And the switch is switched between the power supply and the power line to be conducted and not conducted. The power supply unit can supply power to the power supply line. When the switch is in an ON state, power is supplied from the power source to the power supply 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 supply line at a second voltage. The first control unit transmits the pulse signal to the second control device via the power supply line by means of the change-over switch.

Description

Technical Field

[0001] This invention relates to a power supply system for a vehicle. Background Technology

[0002] Japanese Patent Application Publication No. 2013-93655 discloses an in-vehicle communication system. The system includes: an instrument panel ECU, disposed on the instrument panel and supplied with DC power; a communication ECU, disposed at the rear of the vehicle; and a single transmission path connecting the instrument panel ECU and the communication ECU. The instrument panel ECU has a mechanism for converting the voltage of the DC power supply into a pulse train voltage based on a switch signal. The communication ECU has a mechanism for monitoring the pulse train voltage. Summary of the Invention

[0003] In the technology described in Japanese Patent Application Publication No. 2013-93655, the low level of the pulse train voltage is 0V, and the high level is 12V. Therefore, during the period when the pulse train voltage is 0V, the power supply from the instrument ECU to the communication ECU is cut off. During the period when the power supply to the communication ECU is cut off, the communication ECU supplies power to the load lamp from a capacitor. However, if the capacitor capacitance is insufficient, the lamp's illumination may become unstable. Increasing the capacitor capacitance would easily lead to a larger system and increased product costs.

[0004] The object of the present invention is to provide a technology in which signals can be transmitted more appropriately via a power line supplying power from a first control device to a second control device in a vehicle's power system.

[0005] According to one aspect of the present invention, a vehicle power system includes: 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 operated by power supplied from the first control device via the power line. The first control device includes: a switch for switching between being on and off 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.

[0006] When the switch is in the ON state, power is supplied from the power source to the power line at a first voltage.

[0007] When the switch is in the non-conducting state, power is supplied from the power supply unit to the power line at a second voltage different from the first voltage.

[0008] The first control unit sends a pulse signal to the second control device via the power line by switching the switch.

[0009] The second control device has a second control unit that determines control content based on the pulse signal received via the power line.

[0010] According to the present invention, a technique can be provided in which signals can be transmitted more appropriately via a power line supplying power from a first control device to a second control device in the vehicle's power system. Attached Figure Description

[0011] Hereinafter, with reference to the accompanying drawings, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described, in which the same reference numerals denote the same elements, and wherein:

[0012] Figure 1 This is a diagram that roughly illustrates the configuration of the power supply system of the vehicle in the embodiment.

[0013] Figure 2A This is a diagram representing an example of a pulse signal.

[0014] Figure 2B This is a diagram representing an example of a pulse signal.

[0015] Figure 3 This is a diagram used to illustrate the transition of action patterns.

[0016] Figure 4 It means Figure 1 The flowchart of the operation of the first control device.

[0017] Figure 5 It means Figure 1 The flowchart of the operation of the second control device. Detailed Implementation

[0018] Figure 1 The configuration of the power system 1 of the vehicle according to the embodiment is schematically shown. The power system 1 is installed in a vehicle (not shown) and supplies power to various electrical loads. The vehicle can be a vehicle that uses only an internal combustion engine as its driving force, or it can be an electrified vehicle that uses an electric motor as its driving force. Electrified vehicles include, for example, battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or fuel cell electric vehicles (FCEVs). The vehicle can be a driver-driven vehicle or an autonomous vehicle.

[0019] like Figure 1As shown, the power system 1 includes 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 electronic control unit (ECU).

[0020] The first control device 10 is connected to a DC power supply 14 via power terminal 32. The power supply 14 is, for example, an auxiliary battery of the vehicle. The voltage of the power supply 14 is set to a first voltage V1. The first voltage V1 is, for example, about 13.5V.

[0021] The second control device 12 is connected to the first control device 10 via a power line 16 and operates by power supplied from the first control device 10 via the power line 16.

[0022] The second control device 12 can control whether to supply power to a load (not shown) of the vehicle connected to the output terminal 66. The load may include, for example, various lights such as headlights, peripheral monitoring cameras, various ECUs, etc. The load operates using power supplied from the first control device 10 via the second control device 12.

[0023] 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.

[0024] The input circuit 20 is connected to the vehicle's ignition switch (not shown) via the switch input terminal 34. The input circuit 20 can also be called a switch input interface circuit. The input circuit 20 accepts an input signal indicating whether the ignition switch is on or off, and supplies the switch information indicating whether the ignition switch is on or off to the first control unit 30.

[0025] The communication circuit 22 is connected to another ECU or microcomputer in the vehicle via the communication input terminal 36. The communication circuit 22 can also be referred to as a communication interface circuit. The communication circuit 22 accepts control signals from another ECU or microcomputer and supplies the control information determined by the control signals to the first control unit 30.

[0026] The regulator 24 receives the first voltage V1 from the power supply 14 via the power supply terminal 32, adjusts the first voltage V1 to a specified power supply voltage, and supplies the adjusted power supply voltage to the first control unit 30.

[0027] The power supply unit 26 receives power from the power source 14 via the power supply terminal 32, and can supply power to the power line 16 via the output terminal 38 according to the received power. The power supply unit 26 can also be referred to as a constant power source.

[0028] 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 supply 14.

[0029] Diode D1 has an anode, supplied with a voltage stepped down by the DC / DC converter 40, and a cathode connected to one end of the power supply line 16 via output terminal 38. The cathode of diode D1 outputs a second voltage V2 when switch 28 is in the off state. The second voltage V2 is lower than the first voltage V1, for example, by 10V. The second voltage V2 is preset to a voltage at which the second control device 12 and the load can operate.

[0030] Switch 28 toggles whether conduction is maintained between power supply 14 and power line 16. Switch 28 is, for example, a semiconductor relay or a semiconductor switch. Switch 28 has: one end supplied with a first voltage V1 from power supply 14 via power supply terminal 32; the other end connected to one end of power line 16 via output terminal 38; and a control terminal that supplies control signals from the first control unit 30. That is, the cathode of diode D1 and the other end of switch 28 are both connected to output terminal 38.

[0031] When switch 28 is in the ON state, power is supplied from power source 14 to power line 16 via switch 28 at a first voltage V1. When switch 28 is in the ON state, power is not supplied from power supply unit 26 to power line 16. On the other hand, when switch 28 is in the OFF state, power is supplied from power supply unit 26 to power line 16 at a second voltage V2.

[0032] Therefore, depending on whether switch 28 is in the on state, the voltage change of power line 16 is either a first voltage V1 or a second voltage V2. The first control device 10 can supply power to the second control device 12, enabling the second control device 12 and the load to operate, regardless of whether switch 28 is in the on state.

[0033] The first control unit 30 controls the switch 28. Under specified conditions, the first control unit 30 generates a pulse signal S1 by switching the switch 28 to an on state and a non-on state, and sends 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 a first voltage V1, and the low level of the pulse signal S1 is a second voltage V2. The pulse signal S1 is, for example, a pulse width modulation (PWM) signal. It can also be stated that the first control unit 30 superimposes the pulse signal S1 onto the power line 16. The first control unit 30 can be, for example, configured as a microcomputer.

[0034] The first control unit 30 determines whether the preset conditions for changing the operating mode are met based on the switching information supplied from the input circuit 20 and the control information supplied from the communication circuit 22.

[0035] 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 consumption mode selected when the vehicle is parked. In Mode 1, the vehicle's power supply is off.

[0036] Mode 2 is the operating mode when the ignition switch is turned on. Mode 2 is the mode for performing normal control when the vehicle is in motion. In Mode 2, the vehicle's power supply is in the IG-on state.

[0037] Mode 3 is the mode when the ignition switch is off and intermittent operation is indicated. Mode 3 is selected while the vehicle is parked. Mode 3 is a low-power consumption mode, but it is a mode for periodically operating the load.

[0038] Details of each mode will be described later. More modes can be set as action modes.

[0039] The conditions for changing the operating mode are met, for example, when the ignition switch changes from off to on or from on to off. Alternatively, the conditions for changing the operating mode are met, for example, when intermittent operation is indicated by control information while the ignition switch is off.

[0040] If the conditions for changing the operating mode are not met, the first control unit 30 keeps the switch 28 in the ON state. In this case, no pulse signal S1 is sent, and the normal power supply to the second control device 12 continues.

[0041] 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-established with respect to the changed operating mode during a predetermined transmission period, and then controls the switch 28 to the on state. The frequency and transmission period of the pulse signal S1 can be appropriately determined through experimentation or simulation. For example, the pulse signal S1 may include several to about 10 pulses during the transmission period.

[0042] The frequency of the pulse signal S1 can be, for example, several kHz. A low-pass filter can be placed between the connection point of the other end of switch 28 and the cathode of diode D1 and the output terminal 38. This can improve the S / N ratio of the pulse signal S1.

[0043] For example, the duty cycle associated with mode 1 is 0%. The duty cycle associated with mode 2 is 100%. The duty cycle associated with mode 3 is 50%. The duty cycles of each mode can differ by, for example, 10%.

[0044] Figure 2A , Figure 2B express Figure 1 An example of the pulse signal S1. Figure 2A S1 represents a pulse signal with a duty cycle of 50%. Figure 2B This represents a pulse signal S1 with a 100% duty cycle. In this example, the duty cycle is the on-state duty cycle. The period from time t1 to time t2 is the transmission period.

[0045] like Figure 2A As shown, during the period when the switch is in the non-conducting state during transmission, the 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 transmission.

[0046] Return 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.

[0047] The input circuit 50 is connected to a user-operable switch (not shown) via a switch input terminal 64. This switch, located inside the vehicle, is used to control the operation of a load. The input circuit 50 can also be referred to as a switch input interface circuit. For example, the input circuit 50 accepts an input signal indicating whether the switch is on or off, and supplies this switch information to the second control unit 58.

[0048] The detection unit 52 detects the pulse signal S1 received via the power line 16 and the 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.

[0049] The Zener diode D2 has a cathode and an anode connected to the other end of the power line 16 via a power supply terminal 62.

[0050] The first resistor R1 and the second resistor R2 are connected in series between the anode of the Zener diode D2 and ground.

[0051] Transistor T1 has a control terminal connected to the connection node 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.

[0052] The third resistor R3 has one end that supplies the third voltage V3 and the other end that is connected to the second terminal of transistor T1.

[0053] When the pulse signal S1 is low, that is, when the second voltage V2 is supplied to the power supply terminal 62, the transistor T1 is in a non-conducting state, and the transistor T1 outputs the third voltage V3 as a signal indicating the detection result.

[0054] 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 the conducting state, and the transistor T1 outputs a voltage lower than the third voltage V3 as a signal indicating the detection result.

[0055] The detection unit 52, configured with this circuit, can detect the pulse signal S1 superimposed on the power line 16.

[0056] The regulator 54 adjusts the first voltage V1 or the second voltage V2 of the power supply line 16 to a specified third voltage V3. The third voltage V3 is lower than the second voltage V2.

[0057] Switch 56 toggles whether to connect 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 that supplies a first voltage V1 or a second voltage V2 via the power supply terminal 62; the other end that is connected to the output terminal 66; and a control terminal that supplies control signals from the second control unit 58.

[0058] When switch 56 is in the ON state, power supplied from power line 16 is supplied to the load via switch 56. When switch 56 is in the OFF state, the power supply to the load is cut off.

[0059] 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 based on the detection results of the detection unit 52. The second control unit 58 determines the duty cycle of the pulse signal S1 based on the detection results of the detection unit 52, determines the operating mode based on the determined duty cycle, and executes control corresponding to the determined operating mode. The second control unit 58 can, for example, be configured as a microcomputer.

[0060] Figure 3 This diagram illustrates the transition between operating modes. In the first mode, the first control unit 30 monitors the switching information of the input circuit 20 that is triggered or the control information of the communication circuit 22, while the second control unit 58 monitors the signal representing the detection result based on the detection unit 52.

[0061] In the second mode, the load can be activated, allowing it to fully utilize its function. In the second mode, the second control unit 58 monitors the switching information of the input circuit 50 and controls the switch 56 to either an on or off state based on the switching information, thereby controlling the operation of the load.

[0062] In the third mode, the second control unit 58 intermittently supplies power to the load by intermittently switching the switch 56 from a non-conducting state to a conducting state, causing the load to operate intermittently. For example, the second control unit 58 causes a peripheral surveillance camera, which is the load, to operate periodically.

[0063] like Figure 3 As indicated by the solid arrows, it is possible to switch from mode 1 to mode 2, and from mode 2 to mode 1. Furthermore, it is possible to switch from mode 1 to mode 3, and from mode 3 to mode 1.

[0064] When switching from operating in mode 1 to mode 2, when the first voltage V1 is supplied to the second control device 12, a pulse signal S1 with a 100% duty cycle is also supplied to the second control device 12. Sometimes, switching from operating in mode 1 to mode 2 allows the detection unit 52 to detect the pulse signal S1 with a 100% duty cycle. In such cases, the first control unit 30 can transmit the pulse signal S1 during the transmission period after transmitting the second voltage V2 for a predetermined time shorter than the transmission period. After detecting the second voltage V2 for the predetermined time, the detection unit 52 can detect the pulse signal S1 with a 100% duty cycle during the continuous transmission period. That is, the detection unit 52 can detect the start point of the pulse signal S1.

[0065] Furthermore, in the case where the load connected to the output terminal 66 of the second control device 12 is a constant current circuit and a constant current flows through the load such as an LED, such as Figure 3 As indicated by the dashed arrow, a direct transition can be made between mode 2 and mode 3. This is because, even though the voltage supplied to switch 56 via power terminal 62 varies between voltage 1 V1 and voltage 2 V2 during the transmission of pulse signal S1, the voltage supplied to the load from output terminal 66 varies in the same manner, thus having no substantial effect on the operation of the load.

[0066] Figure 4 It means Figure 1 A flowchart of the operation of the first control device 10. Figure 4 The process, for example, in a vehicle manufacturing plant or repair shop, involves connecting the power source 14 to the power terminal 32 of the first control device 10 and starting the power supply from the power source 14 to the first control device 10.

[0067] The first control unit 30 supplies power to the second voltage V2 by controlling the switch 28 to the non-conducting state (S10). The first control unit 30 determines whether to change the operating mode (S12). If the operating mode is not changed (S12 "No"), the process returns to S12. If the operating mode is changed (S12 "Yes"), the first control unit 30 determines the duty cycle according to the changed operating mode (S14) and sends a PWM signal during transmission (S16). The first control unit 30 supplies power to the first voltage V1 by controlling the switch 28 to the conducting state (S18), and the process returns to S12.

[0068] Figure 5 It means Figure 1 The flowchart of the operation of the second control device 12. Figure 5 The processing began Figure 4 The processing begins, and with Figure 4 The processing is performed in parallel.

[0069] The second control device 12 receives the data. Figure 4 The second voltage V2 is supplied in S10 (S20). The second control unit 58 sets the operation mode to the first mode (S22) and determines whether a PWM signal is received (S24). If no PWM signal is received (S24 "No"), the process returns to S24. If a PWM signal is received (S24 "Yes"), the second control unit 58 determines the operation mode based on the PWM signal (S26) and switches the operation mode (S28). The second control device 12 receives the voltage V2 supplied in S10 (S20). Figure 4 The first voltage V1 supplied in S18 (S30) is processed and returned to S24.

[0070] In addition, Figure 4 In S10, the first control unit 30 can be powered by the first voltage V1. In this case, Figure 5 In S20, the second control device 12 receives the first voltage V1.

[0071] According to the embodiment, the power supply from the first control device 10 to the second control device 12 via the power line 16 can be maintained without interruption, and 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. Therefore, the pulse signal S1 can be transmitted more appropriately via the power line 16.

[0072] Furthermore, it reduces the need for dedicated wiring for transmitting the pulse signal S1. Moreover, the power supply system 1 can be implemented with a simple circuit configuration, eliminating the need for a separate dedicated communication IC. Therefore, the cost of the power supply system 1 can also be reduced.

[0073] The present invention has been described above according to embodiments. The embodiments are merely illustrative, and various modifications and variations in the combination of the constituent elements or processing flows are also within the scope of the present invention, as will be understood by those skilled in the art.

[0074] For example, the pulse signal S1 can be a signal with a fixed pulse width. In this case, for example, a high level of the pulse signal S1 can represent "1", a low level can represent "0", and the pulse signal S1 can represent a digital signal. According to this variation, the degree of freedom in the configuration of the power supply system 1 can be increased.

Claims

1. A power supply system for a vehicle, characterized in that, have: The first control device, which is connected to a power source; and The second control device is connected to the first control device via a power line and is operated by power supplied from the first control device via the power line. The first control device has: A switch that toggles between on and off states between the power source and the power line; A first control unit, which controls the switch; and The power supply unit is capable of supplying power to the power line. When the switch is in the ON state, power is supplied from the power source to the power line at a first voltage. When the switch is in the 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 sends 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 control content based on the pulse signal received via the power line.

2. The power supply system of the vehicle according to claim 1, characterized in that, The pulse signal is a PWM signal.

3. The vehicle power supply system according to claim 2, characterized in that, The second control unit performs control corresponding to the operation mode. When the conditions for changing the operating mode are met, the first control unit sends a pulse signal with a duty cycle pre-established with the changed operating mode during transmission, and then controls the switch to the on state.

4. The power supply system of the vehicle according to any one of claims 1 to 3, characterized in that, The power supply unit has: A DC / DC converter for stepping down the first voltage supplied from the power source; and A diode having: an anode for supplying a voltage stepped down by the DC / DC converter, and a cathode connected to the power supply line to output the second voltage.

5. The power supply system of the vehicle according to any one of claims 1 to 3, characterized in that, The second control device has: The detection unit detects the pulse signal received via the power line; and The regulator adjusts the voltage of the power line to the third voltage. The second control unit operates using the third voltage as its power supply voltage and performs control based on the detection results from the detection unit. The detection unit has: A Zener diode having a cathode connected to the power line; The first resistor and the 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 node of the first resistor and the second resistor; a grounded first terminal; and a second terminal that outputs a signal indicating the detection result to the control unit; and The third resistor has: one end supplying the third voltage; and the other end connected to the second terminal.

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