JP2017034881A - Vehicle power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of charging a sub-battery if a short mode failure occurs in a main power wiring, located on the nearer side to a power control unit than a switch, or in the power control unit.SOLUTION: A power system 1 includes a main battery 4, a main power wiring 10, a PCU 12, an SMR 20, a sub-battery 22, a sub-power wiring 24 and a transformer 36. The transformer 36 includes three coils. A first circuit 28 connects the main power wiring 10 on the main battery 4 side to a first coil, a second circuit 30 connects the main power wiring 10 on the PCU 12 side to a second coil, and a third circuit 32 connects the sub-power wiring 24 to a third coil. When a short mode failure is detected in the PCU 12, the first circuit 28 and the third circuit 32 operate without causing the second circuit 30 to function, so that power can be supplied from the main battery 4 to the sub-battery 22.SELECTED DRAWING: Figure 3

Description

  The technology disclosed in this specification relates to a vehicle power supply system mounted on a vehicle. Note that the “vehicle” in this specification includes both an electric vehicle including only a driving motor without an engine and a hybrid vehicle including both a driving motor and an engine.

  Patent Document 1 discloses a main power source, a main power source wiring connected to the main battery, a power control unit including a smoothing capacitor for smoothing a voltage of the main power source wiring, and a main power source between the main battery and the power control unit. A switch for switching between conductive and non-conductive wiring, a sub-battery having a lower voltage than the main battery, a sub power wiring connected to the sub battery, and a main power wiring and a sub power wiring on the power control unit side of the switch. A vehicle including a DC-DC converter that is connected and capable of performing a step-up operation for boosting power from the sub power supply wiring to the main power supply wiring and supplying power by stepping down from the main power supply wiring to the sub power supply wiring A power supply system is disclosed. In the electric vehicle of Patent Document 1, the voltage of the main battery or the smoothing capacitor is stepped down to a voltage suitable for the sub battery by the DC-DC converter performing the step-down operation, and the sub battery is charged.

JP 2007-318849 A

  In the electric vehicle described above, a DC-DC converter that performs step-up and step-down operations is always connected to the main power supply wiring on the power control unit side rather than the switch. In addition, the main battery has no other connection route to the DC-DC converter except that it is connected via the main power supply wiring. Therefore, for example, if a short mode failure occurs in the power control unit or smoothing capacitor when the main power supply wiring on the power control unit side of the switch is short-circuited with the low voltage side (ground fault state) The voltage of the battery or smoothing capacitor falls to the low voltage side. When a protection circuit and a protection fuse are provided, these function to cut the short circuit. Therefore, even if the DC-DC converter can normally perform step-down operation, the DC-DC converter cannot charge the sub-battery. The present specification provides a technique capable of charging the sub-battery even when the main power supply wiring or the power control unit on the power control unit side of the switch has a short mode failure.

  A vehicle power supply system disclosed in this specification includes a main battery, a main power supply wiring connected to the main battery, a power control unit connected to the main power supply wiring, and a main battery and a power control unit. A switch for switching between conduction and non-conduction of the main power supply wiring, a sub-battery having a lower voltage than the main battery, a sub-power supply wiring connected to the sub-battery, a transformer including a first coil, a second coil, and a third coil A first circuit that connects the main power supply wiring on the main battery side with respect to the switch and the first coil, a second circuit that connects the main power supply wiring on the power control unit side with respect to the switch and the second coil, and a sub power supply wiring; A third circuit for connecting the third coil and a control device are provided. The first circuit has a function of a DC-AC converter, the second circuit has a function of an AC-DC converter, and the third circuit has a function of an AC-DC converter. When a short-circuit failure is detected in the main power supply wiring or the power control unit closer to the power control unit than the switch, the control device does not function as the AC-DC converter of the second circuit, and does not function as the DC of the first circuit. -The AC converter is operated to supply power from the main battery to the sub power supply wiring via the AC-DC converter of the third circuit.

  In the above-described vehicle power supply system, when a short mode failure is detected in the main power supply wiring on the power control unit side or the power control unit from the switch, the DC-AC converter of the first circuit is operated to operate the third circuit. Power is supplied from the main battery to the sub power supply wiring via the AC-DC converter. In other words, in this case, the DC-AC converter of the first circuit and the AC-DC converter of the third circuit can step down the power from the main power supply wiring to the sub power supply wiring and supply power. Thus, even when a short mode failure occurs in the main power supply wiring or power control unit closer to the power control unit than the switch, the voltage is stepped down by the DC-AC converter of the first circuit and the AC-DC converter of the third circuit. The power of the main battery is charged to the sub battery via the sub power supply wiring.

  Details and further improvements of the technology disclosed in this specification will be described in detail in the section of Detailed Description.

It is a block diagram of the power supply system of an Example. It is a figure which shows the schematic structure of the 1st circuit of an Example, a 2nd circuit, and a 3rd circuit. It is explanatory drawing which shows the electric current path | route at the time of charge of a subbattery at the time of failure of a short mode. 6 is a flowchart illustrating a flow of control processing executed by an ECU when a failure occurs in the short mode in the power supply system according to the embodiment.

  A power supply system 1 according to an embodiment will be described with reference to the drawings. The power supply system 1 is a vehicle power supply system mounted on the hybrid vehicle 2. FIG. 1 shows a block diagram of a power supply system 1 of the embodiment. The hybrid vehicle 2 can travel using the power of the engine 61 or can travel using the power of the main battery 4. When traveling using the power of the engine 61, a part of the power generated by the engine 61 is transmitted to drive wheels (not shown) by the power split mechanism 62, while the rest of the power of the engine is used. The first motor 6 generates electric power, and the second motor 8 is driven by the electric power generated by the first motor 6 to rotate the drive wheels. When starting the engine, the power from the main battery 4 of the power supply system 1 is supplied to the first motor 6 so that the first motor 6 functions as a cell motor. When traveling using the power of the main battery 4, the drive wheels are rotated by driving the second motor 8 with the power from the main battery 4. In addition, it is possible to rotate the drive wheels using only the power of the engine 61.

  The power supply system 1 includes a main battery 4, a sub battery 22, a power control unit (PCU) 12, a first circuit 28, a second circuit 30, a third circuit 32, a transformer 36, and a main power supply wiring 10. And a sub power supply wiring 24 and an electronic control unit (ECU) 60. The main battery 4 is a secondary battery such as a nickel metal hydride battery or a lithium ion battery. In this embodiment, the voltage of the main battery 4 is about 300V. The hybrid vehicle 2 can generate electric power with the first motor 6 using the power of the engine, and can charge the main battery 4 with the electric power generated with the first motor 6. Further, when the traveling hybrid vehicle 2 decelerates, regenerative power generation can be performed by the second motor 8, and the electric power generated by the second motor 8 can be charged to the main battery 4.

  The main battery 4 is connected to the PCU 12 via the main power supply wiring 10. The main power supply wiring 10 includes a positive line 10 a connected to the positive terminal of the main battery 4 and a negative line 10 b connected to the negative terminal of the main battery 4.

  The PCU 12 is provided between the main battery 4 and the first motor 6 and the second motor 8. The PCU 12 includes a smoothing capacitor 14, a converter 16, and an inverter 18. The smoothing capacitor 14 smoothes the voltage of the main power supply wiring 10. The voltage of the smoothing capacitor 14 is measured by the voltage sensor 53. The converter 16 boosts the voltage of the power supplied from the main battery 4 to a voltage suitable for driving the first motor 6 and the second motor 8 as necessary. Converter 16 can also step down the voltage of the power generated by first motor 6 or second motor 8 to a voltage suitable for charging main battery 4. In this embodiment, the voltage used to drive the first motor 6 and the second motor 8 is about 600V. The inverter 18 converts the DC power supplied from the main battery 4 into three-phase AC power for driving the first motor 6 and the second motor 8. The inverter 18 can also convert the three-phase AC power generated by the first motor 6 and the second motor 8 into DC power for charging the main battery 4.

  A system main relay (SMR) 20 is provided between the main battery 4 and the PCU 12. The SMR 20 includes a switch 20a that switches between conduction and non-conduction of the positive electrode line 10a of the main power supply wiring 10, and a switch 20b that switches between conduction and non-conduction of the negative electrode line 10b of the main power supply wiring 10. That is, the SMR 20 switches between conduction and non-conduction of the main power supply wiring 10.

  Fuses 5a and 5b are provided between the main battery 4 and the SMR 20. The fuse 5a is blown and non-conductive when a current exceeding the rating flows through the positive electrode line 10a, and the fuse 5b is similarly fused and non-conductive when a current above the rating flows through the negative electrode line 10b. The fuses 5a and 5b protect the main battery 4 and the like by cutting off the current when a current larger than a predetermined magnitude flows in the positive electrode line 10a and the negative electrode line 10b.

  The hybrid vehicle 2 includes a sub battery 22 having a lower voltage than the main battery 4. The sub battery 22 is a secondary battery such as a lead battery. In the present embodiment, the voltage of the sub-battery 22 is about 13V to 14.5V. The sub-battery 22 is connected to an auxiliary device 26 such as a power steering, a headlight, and an air conditioner via a sub power supply wiring 24.

  A first circuit 28 is connected between the main power supply wiring 10 on the main battery 4 side of the SMR 20 and the first coil 36 c of the transformer 36. As will be described in detail later, the transformer 36 includes a second coil 36a and a third coil 36b in addition to the first coil 36c. The second circuit 30 is connected between the main power supply wiring 10 closer to the PCU 12 than the SMR 20 and the second coil 36a. The third circuit 32 is connected between the sub power supply wiring 24 and the third coil 36b. The main power supply wiring 10 closer to the main battery 4 than the SMR 20 is connected to the sub power supply wiring 24 via the first circuit 28, the transformer 36 and the third circuit 32. The combination of the first circuit 28, the transformer 36, and the third circuit 32 can perform a step-down operation in which power is supplied by stepping down from the main power supply wiring 10 closer to the main battery 4 than the SMR 20 to the sub power supply wiring 24.

  Further, the main power supply wiring 10 closer to the PCU 12 than the SMR 20 is connected to the sub power supply wiring 24 through the second circuit 30, the transformer 36 and the third circuit 32. The combination of the second circuit 30, the transformer 36, and the third circuit 32 can perform a step-down operation in which power is supplied by stepping down from the main power supply wiring 10 closer to the PCU 12 than the SMR 20 to the sub power supply wiring 24. The electric power supplied to the sub power supply wiring 24 by the step-down operation is supplied to the sub battery 22 and the auxiliary machine 26.

  The main power supply wiring 10 on the main battery 4 side of the SMR 20 and the main power supply wiring 10 on the PCU 12 side of the SMR 20 are connected via the first circuit 28, the transformer 36, and the second circuit 30. The combination of the first circuit 28, the transformer 36, and the second circuit 30 may perform a supply operation of supplying power from the main power supply wiring 10 on the main battery 4 side of the SMR 20 to the main power supply wiring 10 on the PCU 12 side of the SMR 20. it can. This supply operation can be performed in a state where the SMR 20 is kept non-conductive.

  It is also possible to perform a supply operation of supplying power from the main power supply wiring 10 on the PCU 12 side of the SMR 20 to the main power supply wiring 10 on the main battery 4 side of the SMR 20. With these supply operations, power can be supplied from the PCU 12 to the main battery 4 via the first circuit 28, the transformer 36, and the second circuit 30 in a state where the SMR 20 is kept nonconductive.

  FIG. 2 shows a schematic configuration of the first to third circuits 28, 30 and 32 and the transformer 36. The first to third circuits 28, 30, 32 and the transformer 36 are accommodated in one housing 58. The first circuit 28 is connected to the main power supply wiring 10 through the connection wiring 78.

  The first circuit 28 includes a filter 44, a switching circuit 46, and a backflow prevention switch 45. The filter 33 includes a capacitor 44a. The filter 44 suppresses the generation of noise on the main power supply wiring 10 side. The backflow prevention switch 45 is capable of supplying power from the first circuit 28 to the main power supply wiring 10 on the main battery 4 side by switching on and off of the switching element (that is, the switching element is on) and impossible. (Ie, the switching element is turned off).

  The switching circuit 46 includes switching elements 46a, 46b, 46c, and 46d and free-wheeling diodes 46e, 46f, 46g, and 46h connected in parallel to the respective switching elements 46a, 46b, 46c, and 46d. The switching element 46a and the switching element 46b are connected in series, and the switching element 46c and the switching element 46d are connected in series.

  The switching circuit 46 is connected to the transformer 36. The transformer 36 includes three coils 36a, 36b, and 36c. The first coil 36 c is connected to the switching circuit 46 via the connection wiring 76. That is, the first circuit 28 connects the main power supply wiring 10 closer to the main battery 4 than the SMR 20 and the first coil 36c. The second coil 36 a is connected to the switching circuit 34 of the second circuit 30 through the connection wiring 72. The third coil 36 b is connected to the rectifier circuit 38 of the third circuit 32 via the connection wiring 74. In the transformer 36, electric power can be supplied by stepping down from the second coil 36a to the third coil 36b. Further, the transformer 36 can supply power by stepping down from the first coil 36c to the third coil 36b. In addition, power can be supplied from the first coil 36c to the second coil 36a without changing the voltage, or power can be supplied from the second coil 36a to the first coil 36c without changing voltage. .

  One end of the first coil 36 c is connected between the switching element 46 a and the switching element 46 b via the connection wiring 76, and the other end of the first coil 36 c is connected to the switching element 46 c and the switching element via the connection wiring 76. 46d is connected.

  The switching circuit 46 converts the DC power supplied from the main power supply wiring 10 to the switching circuit 46 into AC power by supplying a PWM signal having a predetermined duty ratio to the switching elements 46a, 46b, 46c, and 46d. . That is, the switching circuit 46 functions as a DC-AC converter. In the switching circuit 46, the AC power supplied from the transformer 36 is converted into DC power by the diodes 46e, 46f, 46g, and 46h. That is, the switching circuit 46 also functions as an AC-DC converter (that is, a rectifier).

  The second circuit 30 connected to the second coil 36 a is connected to the main power supply wiring 10 via the connection wiring 70. That is, the second circuit 30 connects the main power supply wiring 10 closer to the PCU 12 than the SMR 20 and the second coil 36a. The second circuit 30 includes a filter 33, a switching circuit 34, and a backflow prevention switch 31. The filter 33 includes a capacitor 33a. The filter 33 suppresses the generation of noise on the main power supply wiring 10 side. The backflow prevention switch 31 is in a state in which power can be supplied from the second circuit 30 to the main power supply wiring 10 on the PCU 12 side (that is, in a state in which the switching element is on) and in an impossible state by switching the switching element on and off. (That is, the switching element is off).

  The switching circuit 34 includes switching elements 34a, 34b, 34c, 34d and free-wheeling diodes 34e, 34f, 34g, 34h connected in parallel to the respective switching elements 34a, 34b, 34c, 34d. The switching element 34a and the switching element 34b are connected in series, and the switching element 34c and the switching element 34d are connected in series. One end of the second coil 36 a is connected between the switching element 34 a and the switching element 34 b via the connection wiring 72, and the other end of the second coil 36 a is connected to the switching element 34 c and the switching element via the connection wiring 72. 34d.

  The switching circuit 34 converts the DC power supplied from the main power supply wiring 10 to the switching circuit 34 into AC power by supplying a PWM signal having a predetermined duty ratio to the switching elements 34a, 34b, 34c, and 34d. . That is, the switching circuit 34 functions as a DC-AC converter. In the switching circuit 34, the AC power supplied from the transformer 36 is converted into DC power by the diodes 34e, 34f, 34g, and 34h. That is, the switching circuit 34 also functions as an AC-DC converter (that is, a rectifier).

  The third circuit 32 connected to the third coil 36 b is connected to the sub power supply wiring 24. That is, the second circuit 30 connects the sub power supply wiring 24 and the third coil 36b. The third circuit 32 includes a filter 40, a rectifier circuit 38, and a backflow prevention switch 41. The filter 40 includes an inductor 40a and a capacitor 40b. The filter 40 suppresses the generation of noise on the sub power supply wiring 24 side. The backflow prevention switch 41 switches between turning on and off of the switching element, whereby the power can be supplied from the third circuit 32 to the sub power supply wiring 24 (that is, the switching element is on) and the state that is not possible (that is, switching) Switch the element off).

  The rectifier circuit 38 includes diodes 238e, 238g, 238f, and 238h, an inductor 38i, and a capacitor 38j. The diode 238e and the diode 238f are connected in series, and the diode 238g and the diode 238h are connected in series. One end of the third coil 36b is connected between the diode 238e and the diode 238f via the connection wiring 74, and the other end of the third coil 36b is connected between the diode 238g and the diode 238h via the connection wiring 74. It is connected. That is, the rectifier circuit 38 functions as an AC-DC converter (that is, a rectifier). In the rectifier circuit 38, smoothing is also performed by the inductor 38i and the capacitor 38j.

  The first circuit 28 is controlled by the control circuit 43. Specifically, the control circuit 43 controls the duty ratio of the PWM signal supplied to the switching elements 46 a, 46 b, 46 c, 46 d of the switching circuit 46 and the on / off operation of the backflow prevention switch 45. Similarly, the second circuit 30 is controlled by the control circuit 42. The control circuit 43 also controls the on / off operation of the backflow prevention switch 41 of the third circuit.

  The control circuits 42 and 43 are controlled by the ECU 60. The ECU 60 includes a CPU and a memory. The ECU 60 is connected to each part 12, 20, 42, 43 of the power supply system 1 and controls each part 12, 20, 42, 43 according to a program stored in the memory.

  Further, the detection signal VL of the voltage sensor 53 is input to the ECU 60. When the voltage VL of the smoothing capacitor 14 is 0V (zero volt) or a voltage close to 0V based on the detection signal input from the voltage sensor 53, the ECU 60 short-circuits the positive electrode line 10a and the negative electrode line 10b. It is determined that a failure has occurred.

  As described above, a plurality of operations (step-down operation and supply operation) can be performed by the first to third circuits 28, 30 and 32. Next, the main operation among the plurality of operations will be described in more detail. First, the case where the combination of the second circuit 30, the transformer 36, and the third circuit 32 performs the step-down operation by the operation of the second circuit 30 and the third circuit 32 will be described. When the combination of the second circuit 30, the transformer 36, and the third circuit 32 performs a step-down operation, the switching elements 34a, 34b, 34c, 34d operate in the switching circuit 34 of the second circuit 30, and the DC-AC By functioning as a converter, the DC power supplied from the main power supply wiring 10 is converted into AC power. Then, the converted AC voltage is stepped down by the transformer 36, and the rectifier circuit 38 of the third circuit 32 functions as an AC-DC converter, thereby converting AC power into DC power. As a result, power can be supplied by stepping down from the main power supply wiring 10 to the sub power supply wiring 24. That is, by this step-down operation, the electric power generated by the first motor 6 or the second motor 8 can be stepped down to a voltage suitable for charging the sub battery 22 to charge the sub battery 22. This step-down operation is appropriately executed while, for example, the SMR 20 is conducting and the PCU 12 is operating.

  Next, the case where the combination of the first circuit 28, the transformer 36, and the third circuit 32 performs the step-down operation by the operation of the first circuit 28 and the third circuit 32 will be described. When the combination of the first circuit 28, the transformer 36, and the third circuit 32 performs the step-down operation, the switching elements 46a, 46b, 46c, 46d operate in the switching circuit 46 of the first circuit 28, and the DC-AC By functioning as a converter, the DC power supplied from the main power supply wiring 10 is converted into AC power. Then, the converted AC voltage is stepped down by the transformer 36, and the rectifier circuit 38 of the third circuit 32 functions as an AC-DC converter, thereby converting AC power into DC power. As a result, power can be supplied by stepping down from the main power supply wiring 10 to the sub power supply wiring 24. That is, by this step-down operation, the power of the main battery 4 can be stepped down to a voltage suitable for charging the sub battery 22 and the sub battery 22 can be charged.

  Next, a case where a supply operation for supplying power from the main power supply wiring 10 on the main battery 4 side with respect to the SMR 20 to the main power supply wiring 10 on the PCU 12 side with respect to the SMR 20 will be described. In this supply operation, the switching circuit 46 of the first circuit 28 functions as a DC-AC converter, thereby converting DC power supplied from the main power supply wiring 10 into AC power. Then, the converted AC voltage is converted from AC power to DC power in the switching circuit 34 of the second circuit 30 without changing the voltage in the transformer 36. In this case, the switching circuit 34 functions as an AC-DC converter. As a result, power is supplied from the main power supply wiring 10 on the main battery 4 side of the SMR 20 to the main power supply wiring 10 on the PCU 12 side of the SMR 20 without changing the voltage while the SMR 20 maintains the main power supply wiring 10 in the non-conductive state. can do. For example, this supply operation can be used to precharge the smoothing capacitor 14 of the PCU 12 when the SMR 20 is switched from non-conduction to conduction. By precharging so that the voltage of the main battery 4 and the voltage of the smoothing capacitor 14 are matched, it is possible to prevent a large inrush current from flowing through the main power supply wiring 10 immediately after the SMR 20 is switched to conduction. The SMR 20 switches to conduction immediately after the power button (start switch) of the hybrid vehicle 2 is pressed and becomes ready. This supply operation is executed after the ready state and before the SMR 20 switches to conduction, and is not executed thereafter. That is, the second circuit 30 does not function as an AC-DC converter while the SMR 20 is conducting.

  With reference to FIG. 3, a case where a short mode failure has occurred will be described. For example, the short mode failure occurs when the electrode films wound in the smoothing capacitor 14 of the PCU 12 are short-circuited. In addition, it occurs even when the positive electrode line 10 a and the negative electrode line 10 b are short-circuited in the middle of the main power supply wiring 10. When a short mode failure occurs, the voltage VL of the smoothing capacitor 14 becomes 0 V or a voltage close thereto. In such a short circuit state, a large current exceeding the rating flows through the main power supply wiring 10 (the positive line 10a and the negative line 10b). Therefore, at least one of the fuses 5a and 5b provided between the main battery 4 and the SMR 20 is melted, and the current flowing through the main power supply wiring 10 on the PCU 12 side is cut off from the fuses 5a and 5b (SMR 20). Further, when a short mode failure occurs, the wiring connected to the positive line 10a of the converter 16 of the PCU 12 is short-circuited to the low potential side, and the converter 16 does not function. When the short mode failure occurs, the ECU 60 stops the converter 16 of the PCU 12.

  Since the first circuit 28 is connected to the main power supply wiring 10 on the main battery 4 side of the SMR 20 as shown by the thick line in FIG. 3, the power supply system 1 of this embodiment has the fuses 5a and 5b blown. In addition, a connection route between the main battery 4 and the sub-battery 22 is ensured via the first circuit 28 and the third circuit 32. That is, the power supply system 1 according to the present embodiment causes the first circuit 28 to function as a DC-AC converter and brings the backflow prevention switch 41 of the third circuit 32 into a conductive state even when the short mode failure occurs. As a result, the power of the main battery 4 stepped down to a voltage suitable for the sub battery 22 can be charged in the sub battery 22. When a short mode failure occurs, the operation of the second circuit 30 is prohibited as both a DC-AC converter and an AC-DC converter. That is, when a short mode failure occurs, the transformer 36 is disconnected from the main power supply wiring 10 on the PCU 12 side of the SMR 20.

  With reference to FIG. 4, the control executed by the ECU 60 when a short mode failure occurs will be described. When a short mode failure occurs, the hybrid vehicle 2 may be obstructed. By executing the processing shown in FIG. 4, it is possible to continue traveling of the hybrid vehicle 2 even when a short mode failure occurs. The process shown in FIG. 4 is started immediately after the power button (start switch) of the hybrid vehicle 2 is pressed and immediately enters the ready state, and thereafter repeatedly executed at a predetermined cycle (for example, every 5 milliseconds).

  When the process is started, the ECU 60 acquires the voltage VL of the smoothing capacitor 14 based on the detection signal input from the voltage sensor 53 (S2). That is, the voltage VL of the positive electrode line 10a of the main power supply wiring 10 is obtained. Subsequently, the ECU 60 determines whether or not the voltage VL of the smoothing capacitor 14 detected by the voltage sensor 53 is 0 V (S4). Thus, the ECU 60 determines whether or not a short mode failure has occurred. In S4, it may be determined whether or not the voltage VL is a voltage value close to 0V (for example, less than 1V). This is because when the voltage sensor 53 detects a voltage value close to 0 V by a short-circuit resistance value instead of a complete short circuit (dead short circuit), a so-called rare short circuit may occur.

  If the voltage VL of the smoothing capacitor 14 is 0V (S4; YES), it is determined that a short mode failure has occurred, and the process proceeds to S6. On the other hand, when the voltage VL of the smoothing capacitor 14 is not 0 V (S4; NO), it is determined that no short mode failure has occurred, and the process ends.

  In S <b> 6, the ECU 60 transmits an instruction to prohibit the operation of the second circuit 30 to the control circuit 42. The control circuit 42 prohibits the operation of the second circuit 30 in response to the instruction. For example, when the second circuit 30 operates as a DC-AC converter, the control circuit 42 stops supplying the PWM signal to each switching element of the switching circuit 34 of the second circuit 30. Thereby, after that, the second circuit 30 is prohibited from operating as a DC-AC converter. Further, the control circuit 42 prohibits the backflow prevention switch 31 from being turned on in response to the instruction. Thereby, after that, the second circuit 30 is also prohibited from operating as an AC-DC converter. That is, the ECU 60 does not cause the second circuit 30 to function as a DC-AC converter or an AC-DC converter when a short mode failure occurs.

  In S <b> 8, the ECU 60 transmits an instruction to start the operations of the first circuit 28 and the third circuit 32 to the control circuit 43. Specifically, in response to the instruction, the control circuit 43 supplies a predetermined PWM signal to each switching element of the switching circuit 46 of the first circuit 28 and turns on the backflow prevention switch 41 of the third circuit 32. State. Thereby, the ECU 60 operates the DC-AC converter of the first circuit 28, and changes from the main power supply wiring 10 on the main battery 4 side to the sub power supply wiring 24 through the AC-DC converter of the third circuit 32. Supply power. That is, the power of the main battery 4 is supplied to the sub power supply wiring 24 through the first circuit 28 and the third circuit 32.

  Here, as described above, the second circuit 30 does not function as an AC-DC converter. That is, since power cannot be supplied from the second coil 36a to the main power supply wiring 10 closer to the PCU 12 than the SMR 20, the AC power converted by the first circuit 28 is connected to the first coil 36c and the second coil 36c. It is not supplied to the main power supply wiring 10 on the main battery 4 side via the coil 36a. That is, power is not supplied to the main power supply wiring 10 where the short mode failure has occurred.

  Subsequently, in S10, the ECU 60 executes processing for shifting to the retreat travel mode. The retreat travel mode is a travel mode for retreating the hybrid vehicle 2 to a safe place when a failure that may hinder the travel of the hybrid vehicle 2 such as a failure in the short mode described above occurs. For example, the hybrid vehicle 2 can be moved to a repair shop by retreating.

  For example, in the retreat travel mode, the ECU 60 executes the following control. If the hybrid vehicle 2 travels using the engine 61 when a short mode failure occurs, the ECU 60 sets the engine 61 and the power split mechanism 62 so that the travel by the engine 61 is continued. Control. On the other hand, when the short mode failure occurs and the hybrid vehicle 2 is not traveling using the engine 61, the ECU 60 starts the engine 61 so that the engine 61 can travel. The engine 61 and the power split mechanism 62 are controlled. With this control, the hybrid vehicle 2 can be driven using the engine 61 without supplying power to the main power supply wiring 10 in which the short mode failure has occurred.

  When the transition to the retreat travel mode is completed in S10, the ECU 60 ends a series of processes.

  According to such a process, even when a short mode failure occurs, the hybrid vehicle 2 can be driven by the evacuation driving. Even when the retreat travel is executed, the auxiliary equipment 26 such as a power steering, a headlight, and an air conditioner may be driven. However, when a short mode failure occurs, the converter 16 of the PCU 12 is stopped, so that power is not supplied from the PCU 12 to the auxiliary machine 26. Therefore, the auxiliary machine 26 is driven only by the electric power supplied from the sub battery 22. Therefore, if power is not supplied to the sub battery 22, the sub battery 22 continues to be discharged without being charged, and the output voltage of the sub battery 22 drops. According to the above processing, when a short mode failure occurs, the sub-battery 22 is charged with power supplied from the main battery 4 to the sub-power supply wiring 24 via the first circuit 28 and the third circuit 32. The Since the sub-battery 22 is discharged according to the output required for driving the auxiliary machine 26 and is charged by the power of the main battery 4, it is possible to suppress the output voltage of the sub-battery 22 from dropping.

  Points to be noted regarding the technology described in the embodiments will be described. The switching circuit 46 of the first circuit 28 may function as a DC-AC converter and may not function as an AC-DC converter. That is, the first circuit 28 only needs to include at least a DC-AC converter. Further, the switching circuit 34 of the second circuit 30 only needs to function as an AC-DC converter, and may not function as a DC-AC converter. That is, the second circuit 30 only needs to include at least an AC-DC converter.

  Further, the technology described in the embodiments can be applied to an electric vehicle that includes only a traveling motor without an engine. In this case, in the retreat travel mode of S10, for example, the hybrid vehicle is driven by battery-less travel that travels by driving the second motor 8 only by the power generated by the first motor 6 without supplying power from the main battery 4. 2 may be run.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

1: Power supply system 2: Hybrid vehicle 4: Main battery 10: Main power supply wiring 12: PCU
14: Smoothing capacitor 20: SMR
22: Sub battery 24: Sub power supply wiring 26: Auxiliary machine 28: First circuit 30: Second circuit 31, 41, 45: Backflow prevention switch 32: Third circuit 36: Transformer 36a: Second coil 36b: Third coil 36c: 1st coil

Claims (1)

A main battery,
Main power supply wiring connected to the main battery;
A power control unit connected to the main power supply wiring;
A switch that switches between conduction and non-conduction of the main power supply wiring between the main battery and the power control unit;
A sub-battery having a lower voltage than the main battery;
Sub power supply wiring connected to the sub battery;
A transformer including a first coil, a second coil, and a third coil;
A first circuit that connects the main coil and the first coil on the main battery side of the switch;
A second circuit that connects the main coil and the second coil closer to the power control unit than the switch;
A third circuit connecting the sub power supply wiring and the third coil;
Equipped with a control device,
The first circuit has a function of a DC-AC converter;
The second circuit has a function of an AC-DC converter;
The third circuit has an AC-DC converter function;
The control device does not function as the AC-DC converter of the second circuit when a failure in a short mode is detected in the main power supply wiring or the power control unit closer to the power control unit than the switch. A vehicle power supply system that operates the DC-AC converter of the first circuit and supplies electric power from the main battery to the sub power supply wiring via the AC-DC converter of the third circuit.

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