Power-supply circuit and power-supply system

Abstract

A power-supply circuit (70) comprises a power conversion circuit (72). The terminal voltage of a first DC voltage source (60) and the terminal voltage of a second DC voltage source (82) are applied to the power conversion circuit. The power-supply circuit comprises a by-pass path. The by-pass path: bypasses the power conversion circuit and connects the first DC voltage source and an electrical load; and comprises a switch (76) that turns on / off the path.

Description

Power supply circuits and power supply systems

[0001] The present disclosure relates to a power supply circuit and a power supply system.

[0002] For example, Patent Document 1 listed below describes a power conversion circuit that receives the terminal voltage of a first DC voltage source and the terminal voltage of a second DC voltage source as inputs. This power conversion circuit shares a switching element used to convert the terminal voltage of the first DC voltage source and a switching element used to convert the terminal voltage of the second DC voltage source. With this power conversion circuit, even if an abnormality occurs in either the first DC voltage source or the second DC voltage source, it is possible to supply power to an electrical load using the other one.

[0003] Patent No. 5492040

[0004] In the case of the above-described power conversion circuit, if an abnormality occurs in the switching element, there is a risk that neither the first DC voltage source nor the second DC voltage source will be able to supply power to the electrical load.

[0005] In one aspect of the present disclosure, there is provided a power supply circuit, the power supply circuit including a power conversion circuit configured to apply an output voltage to an electric load, and a bypass path, the power conversion circuit being configured to receive a terminal voltage of a first DC voltage source and a terminal voltage of a second DC voltage source, and including a first inductor, a second inductor, and a plurality of switching elements configured to open and close a first loop path, a second loop path, a third loop path, and a fourth loop path, the plurality of switching elements opening and closing the first loop path and the second loop path and the plurality of switching elements opening and closing the third loop path and the fourth loop path being common elements, the first loop path is a path that includes the first DC voltage source and the first inductor but does not include an output terminal of the power conversion circuit, the second loop path is a path that includes the first DC voltage source, the first inductor, and an output terminal of the power conversion circuit, the third loop path is a path that includes the second DC voltage source and the second inductor but does not include an output terminal of the power conversion circuit, the fourth loop path is a path that includes the second DC voltage source, the second inductor, and an output terminal of the power conversion circuit, and the detour path is a path that bypasses the power conversion circuit to connect the first DC voltage source and the electrical load and includes a switch that opens and closes the detour path.

[0006] 7 is a diagram showing the configuration of an in-vehicle system according to a first embodiment. FIG. 8 is a circuit diagram showing the configuration of a power supply circuit in the in-vehicle system of FIG. 1. FIG. 3A and FIG. 3B are circuit diagrams showing power conversion processing with battery power as input. FIG. 4A and FIG. 4B are circuit diagrams showing power conversion processing with capacitor power as input. FIG. 9 is a time chart illustrating the operation of the power supply circuit according to the first embodiment. FIG. 10 is a time chart showing an example of control of the output voltage of a second power conversion circuit according to the first embodiment. FIG. 11 is a diagram showing the configuration of an in-vehicle system according to a second embodiment. FIG. 12 is a circuit diagram showing the configuration of a power supply circuit in the in-vehicle system of FIG.

[0007] First Embodiment A first embodiment will now be described with reference to the drawings. Overall Configuration Fig. 1 shows the configuration of a power supply system according to this embodiment.

[0008] As shown in FIG. 1, a vehicle steering device 10 according to this embodiment includes a steering wheel 12, a steering shaft 14, a reaction motor 16, a reaction inverter 18, and a reaction reduction mechanism 20. The steering wheel 12 is connected to the steering shaft 14. The reaction motor 16 applies a steering reaction force, which is a force resisting steering, to the steering wheel 12 via the steering shaft 14. The reaction motor 16 is connected to the steering shaft 14 via the reaction reduction mechanism 20. As an example, a three-phase synchronous motor is used for the reaction motor 16. The reaction inverter 18 is a DC-AC conversion circuit that converts the voltage of a DC voltage source into AC voltage and applies it to the reaction motor 16. The reaction reduction mechanism 20 is, for example, a worm and wheel.

[0009] Steering device 10 includes steerable wheels 30, a rack shaft 32, a steering motor 34, and a steering inverter 36. The steering angle of the tires of steerable wheels 30 is changed by axial displacement of rack shaft 32. Rack shaft 32 is displaced axially as steering motor 34 rotates. As an example, a three-phase synchronous motor is used for steering motor 34. Steering inverter 36 is a DC / AC conversion circuit that converts the voltage of a DC voltage source into AC voltage and applies it to steering motor 34.

[0010] The reaction force motor 16 and the reaction force inverter 18 are housed in a housing Hb of the reaction force control unit 40. The reaction force control unit 40 controls the steering wheel 12. That is, the reaction force control unit 40 controls the steering reaction force that resists the steering of the driver, which is the control amount of the steering wheel 12 as the control object.

[0011] The reaction force control unit 40 includes a reaction force power supply IC 42 and a reaction force microcomputer 44. The reaction force power supply IC 42 is an integrated circuit that supplies power to the reaction force microcomputer 44 when an IG signal is turned on. When the reaction force microcomputer 44 is turned on, it turns on a reaction force power supply relay 46. In other words, when the IG signal is turned on, the reaction force microcomputer 44 closes the reaction force power supply relay 46.

[0012] The IG signal is a vehicle travel permission signal. The travel permission signal is a signal for switching the vehicle into a state in which it can travel. For example, if the vehicle's thrust generating device is an internal combustion engine only, the travel permission signal is an ignition signal. Also, if the vehicle's thrust generating device is a motor, the travel permission signal may be a signal for switching a relay provided between the motor and the battery to a closed state.

[0013] The reaction force power supply relay 46 is, for example, a field effect transistor. In particular, Fig. 1 shows an example in which the reaction force microcomputer 44 is connected to the cathode of a body diode.

[0014] Reaction force microcomputer 44 is a control circuit that operates reaction force inverter 18 to control the reaction force torque applied to steering wheel 12. Steering motor 34 and steering inverter 36 are housed in housing Hc of steering control unit 50. Steering control unit 50 controls steered wheels 30 as its control object. In other words, steering control unit 50 controls the turning angle of the tires of steered wheels 30 as its control object.

[0015] The steering control unit 50 includes a steering power supply IC 52 and a steering microcomputer 54. The steering power supply IC 52 is an integrated circuit that supplies power to the steering microcomputer 54 when the IG signal is turned on. When the steering microcomputer 54 is turned on, it turns on the steering power supply relay 56.

[0016] The steering power supply relay 56 is, for example, a field effect transistor. In particular, Fig. 1 shows an example in which the steering microcomputer 54 is connected to the cathode of a body diode.

[0017] Steering microcomputer 54 is a control circuit that operates steering inverter 36 to control the torque of steering motor 34. Reaction force control unit 40 and steering control unit 50 are supplied with power from battery 60 via power supply circuit 70. Battery 60 is a secondary battery such as a lead-acid battery, a nickel-metal hydride secondary battery, or a lithium-ion secondary battery. The terminal voltage of battery 60 may be, for example, from several volts to several tens of volts. The terminal voltage of battery 60 may also be several tens of volts.

[0018] Power supply circuit 70 includes a power terminal TP and a control terminal TC. Power terminal TP is a terminal for supplying power to the actuator system. That is, power terminal TP is a terminal for supplying power to reaction force inverter 18 and steering inverter 36. Control terminal TC is a terminal for supplying power to a control unit that operates the actuator system. That is, control terminal TC is a terminal for supplying power to reaction force power supply IC 42, reaction force microcomputer 44, steering power supply IC 52, and steering microcomputer 54.

[0019] That is, power is supplied from control terminal TC to reaction force power supply IC 42 and steering power supply IC 52. Furthermore, power can be supplied from power terminal TP to reaction force power supply IC 42 via reaction force power supply relay 46. Furthermore, power can be supplied from power terminal TP to steering power supply IC 52 via steering power supply relay 56.

[0020] Furthermore, power can be supplied to the reaction force inverter 18 from the power terminal TP via a reaction force power supply relay 46. Furthermore, power can be supplied to the turning inverter 36 from the power terminal TP via a turning power supply relay 56.

[0021] The positive terminal of battery 60 is connected to power supply terminal TS of power supply circuit 70. The negative terminal of battery 60 is connected to ground terminal TG of power supply circuit 70. The negative terminal of battery 60 is also connected to reaction force control unit 40 and turning control unit 50 via ground wiring LG that bypasses power supply circuit 70. Ground wiring LG exists outside housing Ha that houses power supply circuit 70, housing Hb that houses reaction force control unit 40, and housing Hc that houses turning control unit 50. Ground wiring LG may be, for example, a cable with an insulating coating.

[0022] Regarding the power supply circuit: Figure 2 shows the configuration of the power supply circuit 70. The power supply circuit 70 includes a first power conversion circuit 72. The first power conversion circuit 72 includes a series connection of four switching elements SW1 to SW4. Of the two input / output terminals of switching element SW1, the terminal that is not connected to switching element SW2 is the output terminal of the first power conversion circuit 72. Of the two input / output terminals of switching element SW4, the terminal that is not connected to switching element SW3 is connected to the ground terminal TG.

[0023] The switching elements SW1 to SW4 are all field-effect transistors. A body diode is formed in each of the switching elements SW1 to SW4. The forward direction of these body diodes is the direction from the ground terminal TG side to the output side of the first power conversion circuit 72. The first power conversion circuit 72 includes a first inductor 72a connected to the connection point between the switching elements SW2 and SW3. The first power conversion circuit 72 also includes a second inductor 72b connected to the connection point between the switching elements SW1 and SW2.

[0024] Of the two terminals of the first inductor 72a, the terminal not connected to the connection point between the switching element SW2 and the switching element SW3 is connected to a power supply relay 74. The power supply relay 74 opens and closes the connection between the power supply terminal TS and the first power conversion circuit 72. The power supply relay 74 is a normally open relay. The power supply relay 74 is configured by a series connection of two switching elements SW5 and SW6. The switching elements SW5 and SW6 are, for example, field effect transistors. In particular, FIG. 2 shows an example in which the anodes of the body diodes of the switching elements SW5 and SW6 are connected to each other.

[0025] When the power supply relay 74 is closed, the terminal voltage of the battery 60 is applied to the first inductor 72a. A smoothing capacitor 73 is connected to the output terminal of the first power conversion circuit 72. As a result, the output voltage of the first power conversion circuit 72 is applied to the smoothing capacitor 73. Of the two terminals of the smoothing capacitor 73, the terminal not connected to the output terminal is connected to the ground terminal TG.

[0026] The first power conversion circuit 72 is a circuit that generates an output voltage by converting the terminal voltage of the battery 60. More specifically, the switching elements SW1 to SW4 and the first inductor 72a of the first power conversion circuit 72 form a step-up / step-down chopper circuit that uses the terminal voltage of the battery 60 as an input voltage.

[0027] 3A and 3B show the operation of the first power conversion circuit 72 as a buck-boost chopper circuit that uses the terminal voltage of the battery 60 as an input voltage. Fig. 3A shows a state in which the switching elements SW1 and SW2 are turned off and the switching elements SW3 and SW4 are turned on. In this state, the first loop path formed by the battery 60, the first inductor 72a, and the switching elements SW3 and SW4 is closed. This causes a gradual increase in current flowing from the positive terminal of the battery 60 to the first inductor 72a.

[0028] 3B shows a state in which the switching elements SW1 and SW2 are turned on and the switching elements SW3 and SW4 are turned off. In this state, the second loop path including the battery 60, the first inductor 72a, and the switching elements SW1 and SW2 is closed. The second loop path includes the output terminal of the first power conversion circuit 72. Therefore, the second loop path includes components external to the first power conversion circuit 72. For example, the second loop path includes the smoothing capacitor 73. As a result, current flows from the positive electrode of the battery 60 to the smoothing capacitor 73 via the first inductor 72a. At this time, the current flowing through the first inductor 72a gradually decreases.

[0029] Returning to FIG. 2 , the first power conversion circuit 72 is a circuit that converts the charging voltage of the capacitor 82 to generate an output voltage. Specifically, the switching elements SW1 to SW4 and the second inductor 72b of the first power conversion circuit 72 form a step-up / step-down chopper circuit that uses the charging voltage of the capacitor 82 as an input voltage. The capacitor 82 is a lithium-ion capacitor. For example, the upper limit of the charging voltage of the capacitor 82 is lower than the terminal voltage of the battery 60. Furthermore, for example, the fully charged charge amount of the capacitor 82 is smaller than the fully charged charge amount of the battery 60.

[0030] 4A and 4B show the operation of the first power conversion circuit 72 as a buck-boost chopper circuit that uses the charging voltage of the capacitor 82 as an input voltage. Fig. 4A shows a state in which the switching elements SW2 and SW3 are turned on and the switching elements SW1 and SW4 are turned off. In this state, the third loop path formed by the capacitor 82, the second inductor 72b, and the switching elements SW2 and SW3 is closed. This causes a gradual increase in the current flowing from the positive electrode of the capacitor 82 to the second inductor 72b.

[0031] 4B shows a state in which the switching elements SW1 and SW4 are turned on and the switching elements SW2 and SW3 are turned off. In this state, the fourth loop path including the capacitor 82, the second inductor 72b, and the switching elements SW1 and SW4 is closed. The fourth loop path includes the output terminal of the first power conversion circuit 72. Therefore, the fourth loop path includes components external to the first power conversion circuit 72. For example, the fourth loop path includes the smoothing capacitor 73. As a result, current flows from the positive electrode of the capacitor 82 to the smoothing capacitor 73 via the second inductor 72b. At this time, the current flowing through the second inductor 72b gradually decreases.

[0032] Returning to Fig. 2, the output terminal of first power conversion circuit 72 is connected to power terminal TP. Smoothing capacitor 73 is connected between ground terminal TG and power terminal TP. That is, smoothing capacitor 73 is connected in parallel to reaction force inverter 18 and steering inverter 36. Therefore, the second loop circuit and fourth loop circuit can also be said to be paths that include reaction force inverter 18 and steering inverter 36.

[0033] A node N1 between the output terminal of the first power conversion circuit 72 and the power terminal TP is connected to the power supply terminal TS via a bypass relay 76, which is a switch. The bypass relay 76 is a switch that opens and closes the electrical path between the power supply terminal TS and the node N1. Therefore, when the bypass relay 76 is closed, the terminal voltage of the battery 60 is applied to the node N1. The electrical path between the power supply terminal TS, the bypass relay 76, and the node N1 constitutes a detour path that bypasses the first power conversion circuit 72 and connects the battery 60 to the power terminal TP.

[0034] The bypass relay 76 is a normally closed relay. The bypass relay 76 is configured by connecting switching elements SW7 and SW8 in series. The switching elements SW7 and SW8 are P-channel field effect transistors. The anodes of the body diodes of the switching elements SW7 and SW8 are connected to each other. The voltages of the pre-drivers 78 and 80 are applied to the gates of the switching elements SW7 and SW8.

[0035] The pre-driver 78 uses the capacitor 82 as a power source. The pre-driver 78 opens and closes the bypass relay 76 by generating a potential difference between the gate and source or between the gate and drain of the switching elements SW7 and SW8. The pre-driver 78 includes a circuit that switches between connecting either the negative electrode of the capacitor 82 or a point at a higher potential than the negative electrode to the gates of the switching elements SW7 and SW8. Here, the high-potential point may be the positive electrode of the capacitor 82. Alternatively, the high-potential point may be a point at a higher potential than the positive electrode of the capacitor 82. The point at a higher potential than the positive electrode of the capacitor 82 can be realized, for example, by providing the pre-driver 78 with a charge pump that boosts the charging voltage of the capacitor 82.

[0036] The pre-driver 80 uses the battery 60 as a power source. The pre-driver 80 opens and closes the bypass relay 76 by generating a potential difference between the gate and source or between the gate and drain of the switching elements SW7 and SW8. The pre-driver 80 includes a circuit that switches between connecting the gates of the switching elements SW7 and SW8 to either the negative electrode of the battery 60 or a location with a higher potential than the negative electrode. Here, the high-potential location may be the positive electrode of the battery 60. Alternatively, the high-potential location may be a location with a higher potential than the positive electrode of the battery 60. The location with a higher potential than the positive electrode of the battery 60 can be realized, for example, by providing the pre-driver 80 with a charge pump that boosts the terminal voltage of the battery 60.

[0037] The charging voltage of the capacitor 82 is applied to a second power conversion circuit 84. The second power conversion circuit 84 is a circuit that boosts the charging voltage of the capacitor 82. More specifically, the second power conversion circuit 84 is a boost chopper circuit. More specifically, the second power conversion circuit 84 includes an inductor 84a connected to the input terminal and a diode 84b having an anode connected to the inductor 84a. The cathode of the diode 84b serves as the output terminal of the second power conversion circuit 84. The anode of the diode 84b is connected to the ground terminal TG via the switching element SW9.

[0038] A capacitor 85 is provided between the output terminal of the second power conversion circuit 84 and the ground terminal TG. The output voltage of the second power conversion circuit 84 and the voltage applied to the power supply terminal TS are input to the OR circuit 86. The OR circuit 86 outputs the logical sum voltage of the input voltages. That is, if the two input voltages are not equal, the OR circuit 86 outputs the larger voltage. If the two input voltages are equal, the OR circuit 86 outputs the input voltage. The voltage applied to the power supply terminal TS is input to the OR circuit 86 via the power supply relay 74.

[0039] More specifically, the OR circuit 86 includes diodes 86 a and 86 b. The diode 86 a has an anode connected to the power supply terminal TS and a cathode connected to the control terminal TC. The diode 86 b has an anode connected to the output terminal of the second power conversion circuit 84 and a cathode connected to the control terminal TC.

[0040] The control unit 88, which is a processing circuit, is hardware that controls the output voltage of the power supply circuit 70. The control unit 88 may be configured, for example, to include a PU and a storage device. Here, the PU is a software processing device such as a CPU, a GPU, or a TPU. The storage device may be an electrically non-rewritable non-volatile memory. Alternatively, the storage device may be an electrically rewritable non-volatile memory or a storage medium such as a disk medium. Note that the control unit 88 is not limited to one that executes software processing. For example, the control unit 88 may include a dedicated hardware circuit such as an ASIC.

[0041] The control unit 88 operates the switching elements SW1 to SW9 to control the output voltage of the power supply circuit 70. "Operation of the Power Supply Circuit 70" FIG.

[0042] 5 shows an example in which the IG signal is turned on at time t1. In other words, the travel permission signal is turned on, i.e., the state indicating travel permission is entered. After the IG signal is turned on, the control unit 88 is turned on at time t2. When the control unit 88 is turned on, it first turns on the power supply relay 74 at time t3. Then, the control unit 88 starts driving the first power conversion circuit 72 and the second power conversion circuit 84 at time t4.

[0043] If the battery 60 is normal, the control unit 88 causes the power of the battery 60 to be output via the first power conversion circuit 72 by the process shown in Fig. 3. In the event of an abnormality, such as when the terminal voltage of the battery 60 is not applied to the power supply terminal TS, or when the battery 60 cannot provide all the power, the control unit 88 causes the power of the capacitor 82 to be output via the first power conversion circuit 72 by the process shown in Fig. 4.

[0044] 6 , the control unit 88 sets the command value Vout2* for the output voltage Vout2 of the second power conversion circuit 84 to a value lower than the terminal voltage VB of the battery 60. Therefore, when the terminal voltage VB of the battery 60 is applied to the power supply terminal TS, the OR circuit 86 outputs the voltage applied to the power supply terminal TS. That is, in this case, the power output from the OR circuit 86 becomes the output power of the battery 60, and therefore, the power consumption of the capacitor 82 can be suppressed.

[0045] 5, at time t5, the control unit 88 switches the bypass relay 76 to the off state. In other words, it switches the bypass relay 76 to the on state. <Functions and Effects of This Embodiment> Here, the functions and effects of this embodiment will be described.

[0046] First power conversion circuit 72 receives the power of battery 60 and the power charged to capacitor 82. Therefore, even if an abnormality occurs in battery 60, for example, the power charged to capacitor 82 can be supplied to reaction force control unit 40 and steering control unit 50.

[0047] Here, in the first power conversion circuit 72, the switching elements SW1 to SW4 are shared between a circuit portion that receives the battery 60 as an input and a circuit portion that receives the capacitor 82 as an input, which contributes to a reduction in the number of parts.

[0048] However, if an abnormality occurs in switching elements SW1 to SW4, there is a risk that the power of battery 60 and the charging power of capacitor 82 may not be able to be supplied to reaction force control unit 40 and steering control unit 50.

[0049] Therefore, the power supply circuit 70 is provided with a bypass relay 76. The bypass relay 76 connects the positive electrode of the battery 60 to the power terminal TP, bypassing the first power conversion circuit 72. Therefore, even if the first power conversion circuit 72 does not operate normally, the power of the battery 60 can be supplied to the reaction force inverter 18 and the steering inverter 36.

[0050] The present embodiment described above further provides the following advantages and functions: (1-1) The bypass relay 76 is a normally closed relay. This allows power to be quickly supplied to the reaction force inverter 18 and the steering inverter 36 after the IG signal is switched to the on state.

[0051] That is, as shown in FIG. 5 , when the IG signal is switched to the ON state, the power supply relay 74 is closed and then the first power conversion circuit 72 is driven. Therefore, after the IG signal is switched to the ON state, there is a delay before the output voltage of the first power conversion circuit 72 is applied to the reaction force inverter 18 and the steering inverter 36. Therefore, in this embodiment, the bypass relay 76 is of a normally closed type. As a result, when the IG signal is switched, the terminal voltage of the battery 60 is applied to the reaction force power supply relay 46. Furthermore, when the IG signal is switched, the terminal voltage of the battery 60 is applied to the steering power supply relay 56. Therefore, when the IG signal is switched, the terminal voltage of the battery 60 can be applied to the reaction force inverter 18 and the steering inverter 36 as quickly as possible via the bypass relay 76.

[0052] (1-2) The bypass relay 76 is configured by a pair of switching elements SW7 and SW8 connected in series, and the forward directions of the body diodes of these elements are reversed. This makes it possible to prevent current from flowing between the battery 60 and the power terminal TP via the body diodes when the bypass relay 76 is in the off state.

[0053] (1-3) The drive circuits of the bypass relay 76 are pre-drivers 78 and 80 with different power sources. This allows the bypass relay 76 to be operated even if an abnormality occurs in either the battery 60 or the capacitor 82.

[0054] (1-4) The negative terminal of battery 60 is connected to reaction force control unit 40 and turning control unit 50 via ground wiring LG that bypasses housing Ha that houses power supply circuit 70. This makes it possible to reduce the number of terminals of the connector of power supply circuit 70. In other words, if a terminal that is connected to ground terminal TG is provided in power supply circuit 70 and the negative terminal of battery 60 is connected to reaction force control unit 40 and turning control unit 50 via this terminal, the number of terminals of power supply circuit 70 increases.

[0055] Furthermore, the constraints on the flow path cross-sectional area of ​​ground wiring LG are less restrictive than the constraints on the flow path cross-sectional area of ​​the wiring within power supply circuit 70. This reduces the electrical resistance between the negative electrode of battery 60 and reaction force control unit 40 and between battery 60 and reaction force control unit 40 and steering control unit 50. This increases the efficiency of power utilization.

[0056] (1-5) Power from battery 60 and power from capacitor 82 can be supplied to control terminal TC. As a result, even if an abnormality occurs in either battery 60 or capacitor 82, power can be supplied to reaction force control unit 40 and steering control unit 50 via control terminal TC.

[0057] (1-6) The output voltage of the second power conversion circuit 84, which boosts the charging power of the capacitor 82, can be output to the control terminal TC. This makes it possible to apply the necessary voltage to the control terminal TC even when the charging voltage of the capacitor 82 is low.

[0058] (1-7) Even when the power of the capacitor 82 is not used, the control unit 88 drives the second power conversion circuit 84 while controlling the output voltage of the second power conversion circuit 84 to a voltage lower than the terminal voltage of the battery 60. This makes it possible to prevent the reaction force microcomputer 44 and the steering microcomputer 54 from being reset when an abnormality occurs in the battery 60.

[0059] That is, if second power conversion circuit 84 is stopped when the power of capacitor 82 is not being used, the voltage at control terminal TC will drop significantly once in the event of an abnormality such as when the terminal voltage of battery 60 is no longer applied to power supply terminal TS. This could result in reaction force microcomputer 44 and steering microcomputer 54 being reset. Therefore, in this embodiment, by driving second power conversion circuit 84 in advance, when the terminal voltage of battery 60 is no longer applied to power supply terminal TS, the output voltage of second power conversion circuit 84 is immediately applied to control terminal TC. This makes it possible to continue operating reaction force microcomputer 44 and steering microcomputer 54.

[0060] (1-8) A power supply relay 74 is provided between the battery 60 and the first power conversion circuit 72. This makes it possible to prevent power from the battery 60 from flowing to the power terminal TP via the first power conversion circuit 72 when the first power conversion circuit 72 is stopped. In other words, if the power supply relay 74 is not provided, there is a risk that current will flow from the positive electrode of the battery 60 to the power terminal TP via the body diodes of the switching elements SW1 and SW2 when the first power conversion circuit 72 is stopped.

[0061] (1-9) The power supply relay 74 is configured by two switching elements SW5 and SW6 whose body diodes are connected in reverse directions. This prevents current from flowing from the battery 60 through the body diodes of the first power conversion circuit 72 when the first power conversion circuit 72 is stopped, both when the battery 60 is connected correctly and when it is connected in reverse polarity. That is, when the battery 60 is connected in reverse polarity, the body diodes of the switching elements SW3 and SW4 are forward-biased in the path including the switching elements SW3 and SW4, the first inductor 72a, and the battery 60. Therefore, when the power supply relay 74 cannot open the loop path, the loop path enters a closed loop state.

[0062] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment.

[0063] The configuration of the power supply system according to this embodiment is shown in Figures 7 and 8. In Figures 7 and 8, components corresponding to those shown in Figures 1 and 2 are denoted by the same reference numerals for convenience.

[0064] 7 and 8, the negative terminal of battery 60 is connected to reaction force control unit 40 and steering control unit 50 via two ground wires LG. In other words, redundancy is provided in the electrical paths of the ground potential between battery 60 and reaction force control unit 40 and steering control unit 50. This makes it possible to provide the ground potential to reaction force control unit 40 and steering control unit 50 more stably.

[0065] Furthermore, even if the connection between ground terminal TG and the negative electrode of battery 60 is cut off, power can be more reliably supplied to reaction force control unit 40 and turning control unit 50. In other words, it is possible to more reliably close the loop path including bypass relay 76, reaction force inverter 18 (turning inverter 36), ground wiring LG, and battery 60. It is also possible to more reliably close the loop path including battery 60, power supply terminal TS, control terminal TC, reaction force microcomputer 44 (turning microcomputer 54), and ground wiring LG.

[0066] Power supply circuit 70 also has two power terminals TP. More specifically, as shown in FIG. 8 , the output terminal of first power conversion circuit 72 is connected to two different power terminals TP. Bypass relay 76 is also connected to two different power terminals TP. Each of the two power terminals TP is connected to reaction force control unit 40 and turning control unit 50. In other words, the distribution paths for the output power of battery 60 and first power conversion circuit 72 between power supply circuit 70 and reaction force control unit 40 and turning control unit 50 are made redundant. This allows the output power of battery 60 and first power conversion circuit 72 to be supplied to reaction force control unit 40 and turning control unit 50 more stably.

[0067] The power supply circuit 70 also has two control terminals TC. Specifically, as shown in Fig. 8, the power supply circuit 70 has two OR circuits 86. The voltage at the power supply terminal TS and the output voltage of the second power conversion circuit 84 are applied to each of the OR circuits 86. The output voltages of the two OR circuits 86 are connected to different control terminals TC.

[0068] Each of the two control terminals TC is connected to reaction force control unit 40 and steering control unit 50. In other words, the distribution paths for the output power of battery 60 and capacitor 82 between power supply circuit 70 and reaction force control unit 40 and steering control unit 50 are made redundant. This allows the output power of battery 60 and capacitor 82 to be supplied to reaction force control unit 40 and steering control unit 50 more stably.

[0069] <Other Embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0070] Regarding the switch: The switch is not limited to two P-channel field-effect transistors with the anodes of the body diodes connected together. The switch may be, for example, two P-channel field-effect transistors with the cathodes of the body diodes connected together.

[0071] The voltage-controlled switching element constituting the switch is not limited to a P-channel field-effect transistor. For example, an N-channel field-effect transistor may be used. In this case, for example, a P-channel field-effect transistor may be used to open and close the path connecting the gate of the N-channel field-effect transistor and the positive terminal of the battery 60. This allows the switch to be a normally closed type.

[0072] The conduction control terminals of the two voltage-controlled switching elements that constitute the switch do not have to be short-circuited. In this case, for example, the first power conversion circuit 72 may be started to operate, and a switching element having a body diode whose forward direction is the direction from the battery 60 to the power terminal TP may be selectively turned off. In this case, the switching element having a body diode whose reverse direction is the direction from the battery 60 to the power terminal TP may be turned off after the output of the first power conversion circuit 72 has stabilized.

[0073] The switch does not necessarily have to be configured with two voltage-controlled switching elements. For example, the switch may be configured with three or more voltage-controlled switching elements connected in series. In this case, the forward directions of the body diodes of the switching elements are different from each other. Alternatively, the switch may be configured with a single voltage-controlled switching element. Here, the single voltage-controlled switching element constituting the switch may be, for example, an insulated gate bipolar transistor. Also, for example, the single voltage-controlled switching element constituting the switch may be, for example, a P-channel field-effect transistor. Specifically, for example, the bypass relay 76 may be configured with only the switching element SW7. In this case, for example, a voltage-controlled switching element may be provided between the node N1 and the output terminal of the first power conversion circuit 72. The cathode of the body diode of this switching element may be connected to the output terminal of the first power conversion circuit 72.

[0074] The switching elements constituting the switches do not necessarily have to be voltage-controlled switching elements. For example, they may be current-controlled switching elements such as bipolar transistors.

[0075] The semiconductor elements that make up the switch are not limited to transistors. For example, thyristors may be used. The switch does not necessarily have to be made up of semiconductor elements. For example, it may be made up of an electromagnetic relay. Even in this case, it is preferable to use a normally closed type electromagnetic relay.

[0076] The switch does not necessarily have to be a normally closed type. Regarding the drive circuit of the switch: The terminal of the pre-driver 78 may be connected to the ground terminal TG instead of being connected to the connection point of the switching elements SW3 and SW4.

[0077] The switch drive circuit is not limited to the pre-driver 78 powered by the capacitor 82 and the pre-driver 80 powered by the battery 60. For example, the drive circuit may include only one of the pre-drivers 78 and 80.

[0078] Regarding the power relay: The power relay is not limited to two N-channel field effect transistors with the anodes of the body diodes connected together, as exemplified by the power relay 74. The switch may be, for example, two N-channel field effect transistors with the cathodes of the body diodes connected together.

[0079] The voltage-controlled switching element constituting the power relay is not limited to an N-channel field-effect transistor. For example, a P-channel field-effect transistor may be used. In this case, for example, the path that opens and closes the path connecting the gate of the P-channel field-effect transistor and the positive terminal of the battery 60 may be formed by a P-channel field-effect transistor. This allows the switch to be a normally open type.

[0080] It is not essential that the power relay be configured with two voltage-controlled switching elements. For example, the power relay may be configured with three or more voltage-controlled switching elements connected in series. In this case, the forward directions of the body diodes of the switching elements should be different from each other. Alternatively, the power relay may be configured with, for example, a single voltage-controlled switching element. Here, the single voltage-controlled switching element that constitutes the power relay may be, for example, an insulated gate bipolar transistor.

[0081] The switching element that constitutes the power relay does not necessarily have to be a voltage-controlled switching element. For example, it may be a current-controlled switching element such as a bipolar transistor.

[0082] The semiconductor elements that make up the power relay are not limited to transistors. For example, thyristors may be used. The power relay does not necessarily have to be made up of semiconductor elements. For example, it may be made up of an electromagnetic relay. Even in this case, it is preferable to use a normally open type electromagnetic relay.

[0083] Regarding the first power conversion circuit: The switching elements SW1 to SW4 that make up the first power conversion circuit 72 do not necessarily have to be field-effect transistors. For example, they may be insulated gate bipolar transistors. In that case, freewheel diodes may be connected in parallel to the switching elements SW1 to SW4.

[0084] The first power conversion circuit 72 does not necessarily have to include four switching elements SW1 to SW4. For example, the first power conversion circuit 72 may be a circuit in which the switching element SW1 is replaced with a diode. In that case, the circuit portion of the first power conversion circuit 72 that receives power from the battery 60 becomes a boost chopper circuit that receives power from the battery 60 as an input. Furthermore, in that case, the circuit portion of the first power conversion circuit 72 that receives power from the capacitor 82 becomes a boost chopper circuit that receives power from the capacitor 82 as an input.

[0085] The output power of the first power conversion circuit is not limited to being supplied to an actuator system. For example, it may also be supplied to a control system. "Regarding the Second Power Conversion Circuit" The second power conversion circuit 84 does not necessarily have to be a step-up chopper circuit. The second power conversion circuit 84 may be, for example, a step-up / step-down chopper circuit. Also, for example, the second power conversion circuit 84 may be a charge pump.

[0086] Regarding the electrical path that bypasses the housing Ha that houses the power supply circuit: The electrical path that bypasses the housing Ha that houses the power supply circuit 70 is not limited to one or two ground wires LG. For example, it may be three or more ground wires LG.

[0087] "Regarding the first DC voltage source" The first DC voltage source does not necessarily have to be battery 60. For example, it may be a capacitor. In this case, however, it is desirable that the capacitor be provided between the output terminal of the power conversion circuit connected to the secondary battery and ground. This allows the capacitor to charge the power of the secondary battery. Note that this secondary battery may be, for example, a secondary battery that supplies power to a main engine mounted on an electric vehicle.

[0088] Regarding the second DC voltage source, the capacitor 82 is not limited to a lithium ion capacitor. For example, an aluminum electrolytic capacitor may be used.

[0089] The second DC voltage source does not necessarily have to be a capacitor 82. For example, it may be a secondary battery. The fully charged charge amount of the second DC voltage source does not necessarily have to be smaller than the fully charged charge amount of the first DC voltage source.

[0090] The terminal voltage of the second DC voltage source does not necessarily have to be lower than the terminal voltage of the first DC voltage source. "Regarding power system electrical loads" The power system electrical loads are not limited to the reaction force inverter 18 and the turning inverter 36. For example, in a configuration capable of transmitting the power of the steering wheel 12 to the steered wheels 30, the drive circuit of an assist motor that generates torque to assist the operation of the steering wheel 12 may be the electrical load.

[0091] The power system electrical load does not necessarily have to be an electrical load provided by an actuator of a steering system of a vehicle. "Others" The power supply circuit 70 does not necessarily have to include the smoothing capacitor 73.

Claims

1. a power conversion circuit configured to apply an output voltage to an electrical load; a detour route; the power conversion circuit is configured to receive a terminal voltage of a first DC voltage source and a terminal voltage of a second DC voltage source, and includes a first inductor, a second inductor, and a plurality of switching elements; the plurality of switching elements are configured to open and close each of a first loop path, a second loop path, a third loop path, and a fourth loop path; the plurality of switching elements that open and close the first loop path and the second loop path and the plurality of switching elements that open and close the third loop path and the fourth loop path are common elements, the first loop path is a path that includes the first DC voltage source and the first inductor but does not include an output terminal of the power conversion circuit, the second loop path is a path including the first DC voltage source, the first inductor, and an output terminal of the power conversion circuit; the third loop path is a path that includes the second DC voltage source and the second inductor but does not include an output terminal of the power conversion circuit, the fourth loop path is a path including the second DC voltage source, the second inductor, and an output terminal of the power conversion circuit; the bypass path is a path that bypasses the power conversion circuit and connects the first DC voltage source and the electrical load, and includes a switch that opens and closes the bypass path; The power supply circuit, wherein the switch is a normally closed type switch.

2. The switch is a voltage-controlled switching element, a drive circuit for driving the switch; 2. The power supply circuit according to claim 1, wherein the drive circuit uses both the first DC voltage source and the second DC voltage source as power sources.

3. A control unit is provided, The power supply circuit according to claim 1 , wherein the control unit is configured to execute a process of switching the switch to an open state after starting to drive the power conversion circuit.

4. Equipped with a power relay, the power supply relay is configured to open and close between the first DC voltage source and the power conversion circuit; 4. The power supply circuit according to claim 3, wherein the control unit is configured to execute a process of driving the power conversion circuit after the power supply relay is closed.

5. Each of the plurality of switching elements is formed with a body diode whose forward direction is a direction from the positive electrode of the first DC voltage source to the electrical load, Equipped with a power relay, 2. The power supply circuit according to claim 1, wherein the power supply relay is a relay that opens and closes between the first DC voltage source and the power conversion circuit.

6. A power supply circuit comprising: the power supply circuit according to claim 1; and the electrical load; the power supply circuit and the electrical load are housed in different housings, a power supply system including an electrical path that connects the negative electrode of the first DC voltage source and the electrical load, bypassing a housing that houses the power supply circuit;

7. 7. The power supply system according to claim 6, further comprising a plurality of electrical paths that bypass the housing that houses the power supply circuit.

8. 7. The power supply system according to claim 6, wherein the switch is connected to the electrical load via a plurality of electrical paths outside a housing that houses the power supply circuit.

9. The power supply system is mounted on a vehicle, In the vehicle, a process is executed to operate the steered wheels in response to an operation of the steering wheel in a state in which power transmission between the steering wheel and the steered wheels is interrupted, the electrical load includes a reaction motor and a steering motor; the reaction motor is configured to apply a force opposing rotation of the steering wheel; The power supply system according to claim 6 , wherein the steering motor is configured to steer the steerable wheels.