Program for adjusting electrical circuits and output voltage

Abstract

To adjust output values of each battery.SOLUTION: An electric circuit mounted on a vehicle has a first battery, a second battery, a three-phase motor in which windings are connected to each other at a neutral point, an inverter circuit, a port, and a control circuit. When an external electric facility is connected to the port, in a case in which the control circuit determines that the output voltage of the second battery is higher than the output voltage of the first battery, the control circuit executes output voltage adjustment processing of supplying power from the second battery to the electric facility, in a second battery connection state in which the positive electrode of the second battery is connected to a high-potential connection terminal through the neutral point, at least the one winding, at least one upper side reverse conductive switching element and high-potential wiring, and the negative electrode of the second battery is connected to a low-potential connection terminal.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The technology disclosed in this specification relates to an electric circuit and a program for output voltage adjustment.

[0002] Patent Document 1 discloses an electric circuit mounted on a vehicle. This electric circuit has a series circuit of two batteries, an inverter circuit, and a three-phase motor. The inverter circuit drives the three-phase motor by converting the DC power supplied from the series circuit of the batteries into AC power and supplying it to the three-phase motor. Further, this electric circuit has a wiring connecting the connection point of the two batteries and the neutral point of each coil of the three-phase motor. By transferring power between the two batteries through this wiring, each battery can be heated up.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electric circuit having a first battery, a second battery, an inverter circuit, and a three-phase motor, there is a technology for transferring power between each battery and electrical equipment outside the vehicle. The first battery is connected to the electrical equipment via wiring. The second battery is connected to the electrical equipment via the inverter circuit and the three-phase motor. According to this configuration, the two batteries can be connected in parallel to the external electrical equipment. In this type of electric circuit, when the output voltage of the second battery is higher than the output voltage of the first battery, when the first battery and the second battery are connected in parallel, current (hereinafter referred to as leakage current) may flow from the second battery to the first battery through the diode in the inverter circuit. When leakage current flows, the first battery and the second battery deteriorate. In this specification, a technology for adjusting the output voltage of the battery is proposed. [Means for solving the problem]

[0005] The electrical circuit disclosed herein is mounted in a vehicle. The electrical circuit comprises a first battery, a second battery, a three-phase motor, an inverter circuit, a port, and a control circuit. The three-phase motor has three windings: a U-phase winding, a V-phase winding, and a W-phase winding. Each of the three windings has a first connection terminal at one end and a second connection terminal at the other end. At the neutral point, the second connection terminals of the three windings are connected to each other. The inverter circuit is connected to the first connection terminal of the U-phase winding, the first connection terminal of the V-phase winding, and the first connection terminal of the W-phase winding. The port has a high-potential connection terminal and a low-potential connection terminal. The inverter circuit comprises high-potential wiring, low-potential wiring, and three series switch circuits provided for each of the three windings. Each of the series switch circuits has an upper reverse-conducting switching element, which is a reverse-conducting switching element connected between the first connection terminal of the corresponding winding and the high-potential wiring, and a lower reverse-conducting switching element, which is a reverse-conducting switching element connected between the first connection terminal of the corresponding winding and the low-potential wiring. When external electrical equipment is connected to the port, the control circuit performs a determination process and an output voltage adjustment process. The determination process is a process of determining whether the output voltage of the second battery is higher than the output voltage of the first battery. The output voltage adjustment process is a process of lowering the output voltage of the second battery to a value lower than the output voltage of the first battery by supplying power from the second battery to the electrical equipment when the determination process determines that the output voltage of the second battery is higher than the output voltage of the first battery, with the positive electrode of the second battery connected to the high-potential connection terminal via the neutral point, at least one of the windings, at least one of the upper reverse-conducting switching elements and the high-potential wiring, and the negative electrode of the second battery connected to the low-potential connection terminal.

[0006] In this specification, a reverse-conducting switching element refers to an element in which a switching element and a diode are connected in parallel, with the cathode of the diode connected to the high-potential terminal of the switching element and the anode of the diode connected to the low-potential terminal of the switching element. The switching element may be a semiconductor switching element such as a field-effect transistor or an insulated-gate bipolar transistor. The diode may be a pn diode or a Schottky barrier diode. The switching element and the diode may be provided on a common semiconductor substrate or on separate semiconductor substrates. In this specification, "on" of a reverse-conducting switching element means that the switching element of the reverse-conducting switching element is turned on, and "off" of a reverse-conducting switching element means that the switching element of the reverse-conducting switching element is turned off.

[0007] In this electrical circuit, if the output voltage of the second battery is higher than that of the first battery, an output voltage adjustment process reduces the output voltage of the second battery to a value lower than that of the first battery. Therefore, leakage current can be prevented when the first and second batteries are subsequently connected in parallel. [Brief explanation of the drawing]

[0008] [Figure 1] A circuit diagram of the electrical circuit (showing the connection paths to the first and second batteries). [Figure 2] A circuit diagram of an electrical circuit (a diagram showing the path of leakage current). [Figure 3] A flowchart illustrating the processes executed by the control circuit. [Modes for carrying out the invention]

[0009] In the example of the electrical circuit described above, the control circuit may, when the output voltage of the second battery drops to a value lower than the output voltage of the first battery during the output voltage adjustment process, transfer power between the second battery and the electrical equipment with the positive electrode of the second battery connected to the neutral point, at least one winding, at least one upper reverse-conducting switching element, and the high-potential wiring to the high-potential connection terminal, and the negative electrode of the second battery connected to the low-potential connection terminal, and also perform a parallel power transfer process which transfers power between the first battery and the electrical equipment with the positive electrode of the first battery connected to the high-potential connection terminal and the negative electrode of the first battery connected to the low-potential connection terminal.

[0010] The parallel power transfer process may be a process of supplying power from the first battery and the second battery to external electrical equipment (i.e., a process of discharging the first battery and the second battery), or it may be a process of supplying power from external electrical equipment to the first battery and the second battery (i.e., a process of charging the first battery and the second battery).

[0011] In the example of the electrical circuit described above, the control circuit may start the parallel power transfer process with the current flowing between the electrical circuit and the electrical equipment reduced when the output voltage of the second battery falls to a value lower than the output voltage of the first battery during the output voltage adjustment process.

[0012] This configuration helps to suppress the degradation of the switch (e.g., relay switch) that connects the first battery to the port.

[0013] In the example of the electrical circuit described above, the control circuit may execute the parallel power transfer process if it determines in the determination process that the output voltage of the second battery is lower than the output voltage of the first battery.

[0014] In the example of the electrical circuit described above, the control circuit may perform the parallel power transfer process such that the output voltage of the second battery is kept lower than the output voltage of the first battery.

[0015] This configuration prevents leakage current during parallel power transfer processing.

[0016] The electrical circuit 10 of the embodiment shown in Figure 1 is mounted on a vehicle. The electrical circuit 10 includes a first battery 11, a second battery 12, an inverter circuit 30, and a three-phase motor 40. The three-phase motor 40 is the vehicle's driving motor. The inverter circuit 30 converts the DC power supplied from the first battery 11 and the second battery 12 into AC power and supplies it to the three-phase motor 40. As a result, the three-phase motor 40 rotates the drive wheels, causing the vehicle to move.

[0017] The three-phase motor 40 has a U-phase winding 44U, a V-phase winding 44V, and a W-phase winding 44W. Terminals 41U and 42U are provided at both ends of winding 44U. Terminals 41V and 42V are provided at both ends of winding 44V. Terminals 41W and 42W are provided at both ends of winding 44W. Terminals 42U, 42V, and 42W are connected to each other at the neutral point 46.

[0018] The inverter circuit 30 is connected to terminals 41U, 41V, and 41W of the three-phase motor 40. The inverter circuit 30 has a high-potential wiring 31, a low-potential wiring 32, and three series switch circuits 34U, 34V, and 34W. Each of the series switch circuits 34U, 34V, and 34W consists of two reverse-conducting switching elements 35 connected in series between the high-potential wiring 31 and the low-potential wiring 32. Hereinafter, of the two reverse-conducting switching elements 35 connected in series, the one connected to the high-potential wiring 31 may be referred to as the upper reverse-conducting switching element, and the one connected to the low-potential wiring 32 may be referred to as the lower reverse-conducting switching element. Each reverse-conducting switching element 35 has a structure in which a switching element (e.g., an insulated-gate bipolar transistor or a field-effect transistor) and a diode (e.g., a pn diode or a Schottky barrier diode) are connected in antiparallel. In each reverse-conducting switching element 35, the cathode of the diode is connected to the high-potential terminal (i.e., the collector or drain) of the switching element, and the anode of the diode is connected to the low-potential terminal (i.e., the emitter or source) of the switching element.

[0019] The series switch circuit 34U is provided with respect to the winding 44U. The series switch circuit 34U has an upper reverse-conducting switching element 35UU and a lower reverse-conducting switching element 35UL. The high-potential terminal of the upper reverse-conducting switching element 35UU is connected to the high-potential wiring 31. The low-potential terminal of the upper reverse-conducting switching element 35UU and the high-potential terminal of the lower reverse-conducting switching element 35UL are connected to terminal 41U. The low-potential terminal of the lower reverse-conducting switching element 35UL is connected to the low-potential wiring 32.

[0020] The series switch circuit 34V is provided for the winding 44V. The series switch circuit 34V has an upper reverse conduction switching element 35VU and a lower reverse conduction switching element 35VL. The high-potential terminal of the upper reverse conduction switching element 35VU is connected to the high-potential wiring 31. The low-potential terminal of the upper reverse conduction switching element 35VU and the high-potential terminal of the lower reverse conduction switching element 35VL are connected to the terminal 41V. The low-potential terminal of the lower reverse conduction switching element 35VL is connected to the low-potential wiring 32.

[0021] The series switch circuit 34W is provided for the winding 44W. The series switch circuit 34W has an upper reverse conduction switching element 35WU and a lower reverse conduction switching element 35WL. The high-potential terminal of the upper reverse conduction switching element 35WU is connected to the high-potential wiring 31. The low-potential terminal of the upper reverse conduction switching element 35WU and the high-potential terminal of the lower reverse conduction switching element 35WL are connected to the terminal 41W. The low-potential terminal of the lower reverse conduction switching element 35WL is connected to the low-potential wiring 32.

[0022] A capacitor 36 is connected between the high-potential wiring 31 and the low-potential wiring 32. Also, a voltmeter 37 is connected between the high-potential wiring 31 and the low-potential wiring 32.

[0023] A neutral point wiring 50 is connected to the neutral point 46 of the three-phase motor 40. A capacitor 60 is connected between the neutral point wiring 50 and the low-potential wiring 32. Also, a voltmeter 61 is connected between the neutral point wiring 50 and the low-potential wiring 32.

[0024] The electric circuit 10 has a port 70. A connector of an electrical equipment outside the vehicle (hereinafter referred to as external electrical equipment) can be connected to the port 70. The port 70 has a high-potential connection terminal 71 and a low-potential connection terminal 72.

[0025] The electrical circuit 10 has a plurality of relay switches 81 to 88. When each relay switch is switched, the interconnection relationships of the first battery 11, the second battery 12, the high-potential wiring 31, the low-potential wiring 32, the neutral point 46, and the port 70 are changed.

[0026] The relay switch 81 is located between the negative terminal of the first battery 11 and the positive terminal of the second battery 12. When the relay switch 81 is turned on, the first battery 11 and the second battery 12 are connected in series.

[0027] The relay switch 82 is located between the negative terminal of the first battery 11 and the negative terminal of the second battery 12. When the relay switch 82 is turned on, the negative terminal of the first battery 11 and the negative terminal of the second battery 12 are connected.

[0028] An ammeter 20 and a relay switch 83 are connected in series between the positive terminal of the first battery 11 and the high-potential wiring 31. When the relay switch 83 is turned on, the positive terminal of the first battery 11 is connected to the high-potential wiring 31.

[0029] The relay switch 84 is located between the negative terminal of the second battery 12 and the low-potential wiring 32. When the relay switch 84 is turned on, the negative terminal of the second battery 12 is connected to the low-potential wiring 32.

[0030] The relay switch 85 is located between the low-potential connection terminal 72 and the low-potential wiring 32. When the relay switch 85 is turned on, the low-potential connection terminal 72 is connected to the low-potential wiring 32.

[0031] The relay switch 86 is located between the high-potential connection terminal 71 and the high-potential wiring 31. When the relay switch 86 is turned on, the high-potential connection terminal 71 is connected to the high-potential wiring 31.

[0032] An ammeter 52 and a relay switch 87 are connected in series between the positive terminal of the second battery 12 and the neutral point wiring 50. A relay switch 88 is also provided on the neutral point wiring 50. When relay switches 87 and 88 are turned on, the positive terminal of the second battery 12 is connected to the neutral point 46.

[0033] The electrical circuit 10 has a control circuit 90. The control circuit 90 is composed of a CPU, memory, etc. The memory of the control circuit 90 stores a program for controlling the electrical circuit 10. The control circuit 90 controls the switching elements of each reverse-conducting switching element 35 and the relay switches 81-88 according to the program. The control circuit 90 can also communicate with external electrical equipment when external electrical equipment is connected to port 70.

[0034] The control circuit 90 can perform normal operation to drive the three-phase motor 40. In normal operation, the control circuit 90 turns on relay switches 81, 83, and 84, and turns off relay switches 82, 85, 86, 87, and 88. In this state, the first battery 11 and the second battery 12 are connected in series between the high-potential wiring 31 and the low-potential wiring 32. As a result, the DC voltage output by the series circuit of the first battery 11 and the second battery 12 is applied between the high-potential wiring 31 and the low-potential wiring 32. The control circuit 90 converts the DC power applied between the high-potential wiring 31 and the low-potential wiring 32 into AC power by switching the switching elements of each reverse-conducting switching element 35, and supplies the AC power to the three-phase motor 40. This causes the three-phase motor 40 to rotate. The control circuit 90 controls the torque and rotational speed of the three-phase motor 40 by changing the amplitude, frequency, etc. of the AC current supplied to the three-phase motor 40.

[0035] As described above, external electrical equipment is connected to port 70. When external electrical equipment is connected to port 70, the control circuit 90 can perform power transfer processing to transfer power between the electrical circuit 10 and the external electrical equipment.

[0036] When transferring power between the first battery 11 and external electrical equipment, the control circuit 90 forms the connection path shown by arrow 100 in Figure 1. Specifically, the control circuit 90 turns on relay switches 82, 83, 84, 85, and 86, and turns off relay switch 81. In this state, the positive terminal of the first battery 11 is connected to the high-potential connection terminal 71 of port 70 via relay switches 83 and 86. Also, the negative terminal of the first battery 11 is connected to the low-potential connection terminal 72 of port 70 via relay switches 82, 84, and 85. In this state, when a voltage is applied to port 70 by external electrical equipment in a direction such that the high-potential connection terminal 71 is at a higher potential than the low-potential connection terminal 72, current flows through the path shown by arrow 100, and the first battery 11 is charged. In other words, the first battery charging process is performed. Furthermore, when the first battery 11 is connected to the external electrical equipment and the external electrical equipment connects a device between the high-potential connection terminal 71 and the low-potential connection terminal 72, current flows in the opposite direction to arrow 100, and power is supplied from the first battery 11 to the external electrical equipment. In other words, the first battery power supply process is executed.

[0037] When transferring power between the second battery 12 and external electrical equipment, the control circuit 90 forms the connection path shown by arrow 102 in Figure 1. Specifically, the control circuit 90 turns on relay switches 84, 85, 86, 87, and 88, and turns off relay switch 81. The control circuit 90 also turns off the lower reverse-conducting switching elements 35UL, 35VL, and 35WL, and turns on at least one of the upper reverse-conducting switching elements 35UU, 35VU, and 35WU. Arrow 102 illustrates the path when the upper reverse-conducting switching element 35VU is turned on. In this state, the positive terminal of the second battery 12 is connected to the high-potential connection terminal 71 of port 70 via relay switches 87, 88, neutral point 46, winding 44V, upper reverse-conducting switching element 35VU, and relay switch 86. Furthermore, the negative terminal of the second battery 12 is connected to the low-potential connection terminal 72 of port 70 via relay switches 84 and 85. In this state, when a voltage is applied to port 70 by external electrical equipment in a direction in which the high-potential connection terminal 71 is at a higher potential than the low-potential connection terminal 72, current flows in the path shown by arrow 102 and the second battery 12 is charged. That is, the second battery charging process is performed. Note that when the second battery 12 is being charged, the upper reverse-conducting switching element may be switched periodically. In this case, the inverter circuit 30 and the windings of the three-phase motor 40 operate as a step-down converter circuit, and the charging current to the second battery 12 can be suppressed. Also, when the external electrical equipment connects a device between the high-potential connection terminal 71 and the low-potential connection terminal 72 while the second battery 12 is connected to the external electrical equipment, current flows in the opposite direction to arrow 102, and power is supplied from the second battery 12 to the external electrical equipment. That is, the second battery power supply process is performed. In addition, during the second battery power supply process, current flows through the diode of the upper reverse-conducting switching element, so the switching element of the upper reverse-conducting switching element may be turned off.

[0038] As explained above, the power transfer process includes the first battery charging process, the first battery power supply process, the second battery charging process, and the second battery power supply process.

[0039] Furthermore, the control circuit 90 can connect the first battery 11 and the second battery 12 in parallel to port 70 via the paths shown by arrows 100 and 102. When the first battery 11 and the second battery 12 are connected in parallel to port 70, it is possible to perform a process that simultaneously executes the first battery charging process and the second battery charging process (hereinafter referred to as parallel charging process), and a process that simultaneously executes the first battery power supply process and the second battery power supply process (hereinafter referred to as parallel power supply process). In addition, when the first battery 11 and the second battery 12 are connected in parallel to port 70, the control circuit 90 can selectively execute a parallel charging process and a parallel power supply process depending on the situation (hereinafter referred to as parallel charging and power supply process).

[0040] When the first battery 11 and the second battery 12 are connected in parallel while the output voltage V2 of the second battery 12 is higher than the output voltage V1 of the first battery 11, leakage current flows from the second battery 12 to the first battery 11 through the path shown by arrow 104 in Figure 2. That is, when the output voltage V2 of the second battery 12 is higher than the output voltage V1 of the first battery 11, a forward voltage is applied to the upper reverse conducting switching elements 35UU, 35VU, and 35WU diodes, causing these diodes to turn on. As a result, leakage current flows from the positive terminal of the second battery 12 to the positive terminal of the first battery 11 via relay switches 87, 88, neutral point 46, windings 44U, 44V, 44W, the upper reverse conducting switching elements 35UU, 35VU, and 35WU diodes, and relay switch 83. Note that arrow 104 illustrates the path through the upper reverse conducting switching element 35VU diode. Since there is no power-consuming load in the path through which the leakage current flows, the leakage current is relatively large. As a result, when leakage current flows, the first battery 11 and the second battery 12 deteriorate.

[0041] The control circuit 90 performs the process shown in Figure 3 in order to perform power transfer processing while preventing leakage current. When external electrical equipment is connected to port 70, the control circuit 90 performs the process shown in Figure 3 according to the program stored in memory. At the start of the process in Figure 3, the vehicle is stopped, and relay switches 81-88 and all reverse-conducting switching elements 35 are off. In step S2, the control circuit 90 detects the output voltage V1 of the first battery 11 and the output voltage V2 of the second battery 12. For example, the control circuit 90 can turn on relay switches 82, 83, and 84 and detect the output voltage V1 of the first battery 11 using the voltmeter 37. Alternatively, for example, the control circuit 90 can turn on relay switches 84 and 87 and detect the output voltage V2 of the second battery 12 using the voltmeter 61. In step S2, no current is flowing through batteries 11 and 12. Therefore, the output voltages V1 and V2 detected in step S2 are OCV (Open Circuit Voltage). The control circuit 90 determines whether the output voltage V2 is higher than the output voltage V1.

[0042] If the output voltage V2 is less than or equal to the output voltage V1 (i.e., NO in step S2), the control circuit 90 performs parallel charging and power supply processing in step S14. When the output voltage V2 is less than or equal to the output voltage V1, no leakage current occurs even if the first battery 11 and the second battery 12 are connected in parallel, so parallel charging and power supply processing can be performed appropriately in step S14.

[0043] If the output voltage V2 is higher than the output voltage V1 (i.e., the answer is YES in step S2), the control circuit 90 performs the second battery power supply process in step S4. Specifically, the control circuit 90 connects the second battery 12 to port 70 via the path shown by arrow 102 in Figure 1 and commands the control circuit 90 to perform a power supply operation to the external electrical equipment. As a result, current flows in the opposite direction to arrow 102 in Figure 1, and power is supplied from the second battery 12 to the external electrical equipment. Thus, in step S4, the second battery 12 is discharged, and the output voltage V2 of the second battery 12 gradually decreases. Also in step S4, the control circuit 90 disconnects the first battery 11 from port 70 by turning off relay switches 82 and 83. Therefore, in step S4, the output voltage V1 of the first battery 11 does not change.

[0044] After performing step S4 for a predetermined time, the control circuit 90 executes step S6. In step S6, the control circuit 90 determines whether the output voltage V2 is higher than the output voltage V1. As described above, the output voltage V1 of the first battery 11 does not change in step S4, so in step S6, the output voltage V1 measured in step S2 can be used as a comparison value. In step S6, the control circuit 90 also measures the output voltage V2. Here, the control circuit 90 may measure the output voltage V2 (i.e., CCV (Closed Circuit Voltage)) while current is flowing through the second battery 12, or it may measure the output voltage V2 (i.e., OCV) with the current to the second battery 12 stopped. The control circuit 90 repeats steps S4 and S6 until the output voltage V2 is less than or equal to the output voltage V1. During the repetition of steps S4 and S6, the output voltage V2 decreases until it is less than or equal to the output voltage V1. In this way, steps S4 and S6 adjust the output voltage V2 so that it is less than or equal to the output voltage V1. When the output voltage V2 falls below the output voltage V1, the control circuit 90 determines NO in step S6 and executes step S8.

[0045] In step S8, the control circuit 90 determines whether the external electrical equipment can limit the charging and supplying current (i.e., the current flowing between the electrical circuit 10 and the external electrical equipment via port 70). That is, the control circuit 90 determines whether the charging and supplying current can be reduced from its current value. This determination is made based on the type of external electrical equipment and its operating state. If the charging and supplying current cannot be limited, the control circuit 90 executes the charging and supplying process using the second battery 12 in step S10. That is, the control circuit 90 selectively executes the second battery charging process and the second battery power supply process. Also in step S10, the control circuit 90 turns off the relay switches 82 and 83, disconnecting the first battery 11 from port 70. The control circuit 90 repeats steps S8 and S10 until it becomes possible to limit the charging and supplying current with the external electrical equipment. If it is not possible to limit the charging and supplying current with the external electrical equipment, steps S8 and S10 continue until the power transfer process is completed.

[0046] When it becomes possible to limit the charging and supplying current with external electrical equipment, the control circuit 90 determines YES in step S8 and executes step S12. In step S12, the control circuit 90 commands the external electrical equipment to limit the charging and supplying current. After that, the control circuit 90 turns on relay switches 82 and 83 to start the parallel charging and supplying process in step S14. In this way, the control circuit 90 turns on relay switches 82 and 83 with the charging and supplying current reduced, which prevents a high inrush current from flowing through relay switches 82 and 83. This prevents the relay switches 82 and 83 from becoming stuck. When step S14 starts, the control circuit 90 releases the limit on the charging and supplying current. This allows the parallel charging and supplying process to be executed with a high charging and supplying current.

[0047] In the parallel charging and power supply operation of step S14, the control circuit 90 controls the current flowing to each battery so that the output voltage V1 remains higher than the output voltage V2. For example, when the output voltage V2 rises to a value close to the output voltage V1, the control circuit 90 periodically switches the upper reverse conduction switching elements 35UU, 35VU, and 35WU to limit the charging current to the second battery 12. This prevents the output voltage V2 from becoming higher than the output voltage V1. Therefore, leakage current can be prevented during the execution of step S14.

[0048] As described above, the electrical circuit 10 of the embodiment makes it possible to perform power transfer processing while preventing the generation of leakage current.

[0049] In this embodiment, the second battery charging and power supply process was performed in step S10, but either the second battery charging process or the second battery power supply process may be performed alone.

[0050] Furthermore, step S14 of the embodiment is an example of parallel power transfer processing. In this embodiment, parallel charging and supply processing was performed as parallel power transfer processing, but either parallel charging processing or parallel power supply processing alone may be performed as parallel power transfer processing.

[0051] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness. [Explanation of Symbols]

[0052] 11: Battery No. 1 12: Second battery 30: Inverter Circuit 31: High-voltage wiring 32: Low potential wiring 34U~34W: Series switch circuit 40: Three-phase motor 46: Neutral point 70: Port

Claims

1. An electrical circuit installed in a vehicle, First battery and The second battery, A three-phase motor having three windings, a U-phase winding, a V-phase winding, and a W-phase winding, each of the three windings having a first connection terminal at one end and a second connection terminal at the other end, and the second connection terminals of the three windings being connected to each other at the neutral point, An inverter circuit connected to the first connection terminal of the U-phase winding, the first connection terminal of the V-phase winding, and the first connection terminal of the W-phase winding, A port having high-potential connection terminals and low-potential connection terminals, Control circuit, It has, The inverter circuit, High-voltage wiring and, Low-voltage wiring and, Three series switch circuits are provided for each of the three windings, It has, Each of the series switch circuits has an upper reverse-conducting switching element which is a reverse-conducting switching element connected between the first connection terminal of the corresponding winding and the high-potential wiring, and a lower reverse-conducting switching element which is a reverse-conducting switching element connected between the first connection terminal of the corresponding winding and the low-potential wiring. When external electrical equipment is connected to the port, the control circuit will activate. A determination process for determining whether the output voltage of the second battery is higher than the output voltage of the first battery, If the determination process determines that the output voltage of the second battery is higher than the output voltage of the first battery, an output voltage adjustment process is performed to lower the output voltage of the second battery to a value lower than the output voltage of the first battery by supplying power from the second battery to the electrical equipment while the positive electrode of the second battery is connected to the neutral point, at least one winding, at least one upper reverse-conducting switching element, and the high-potential wiring to the high-potential connection terminal, and the negative electrode of the second battery is connected to the low-potential connection terminal. An electrical circuit that performs this operation.

2. The electrical circuit according to claim 1, wherein the control circuit, when the output voltage of the second battery falls to a value lower than the output voltage of the first battery in the output voltage adjustment process, transfers power between the second battery and the electrical equipment with the positive electrode of the second battery connected to the neutral point, at least one winding, at least one upper reverse-conducting switching element, and the high-potential wiring to the high-potential connection terminal, and the negative electrode of the second battery connected to the low-potential connection terminal, and also performs a parallel power transfer process which transfers power between the first battery and the electrical equipment with the positive electrode of the first battery connected to the high-potential connection terminal and the negative electrode of the first battery connected to the low-potential connection terminal.

3. The electrical circuit according to claim 2, wherein the control circuit starts the parallel power transfer process with the current flowing between the electrical circuit and the electrical equipment reduced when the output voltage of the second battery falls to a value lower than the output voltage of the first battery during the output voltage adjustment process.

4. The electrical circuit according to claim 2 or 3, wherein the control circuit executes the parallel power transfer process when it determines in the determination process that the output voltage of the second battery is lower than the output voltage of the first battery.

5. The electrical circuit according to claim 2 or 3, wherein the control circuit performs the parallel power transfer process such that the output voltage of the second battery is maintained to be lower than the output voltage of the first battery.

6. A program executed by an electrical circuit installed in a vehicle, The aforementioned electrical circuit First battery and The second battery, A three-phase motor having three windings, a U-phase winding, a V-phase winding, and a W-phase winding, each of the three windings having a first connection terminal at one end and a second connection terminal at the other end, and the second connection terminals of the three windings being connected to each other at the neutral point, An inverter circuit connected to the first connection terminal of the U-phase winding, the first connection terminal of the V-phase winding, and the first connection terminal of the W-phase winding, A port having high-potential connection terminals and low-potential connection terminals, Control circuit, It has, The inverter circuit, High-voltage wiring and, Low-voltage wiring and, Three series switch circuits are provided for each of the three windings, It has, Each of the series switch circuits has an upper reverse-conducting switching element which is a reverse-conducting switching element connected between the first connection terminal of the corresponding winding and the high-potential wiring, and a lower reverse-conducting switching element which is a reverse-conducting switching element connected between the first connection terminal of the corresponding winding and the low-potential wiring. When external electrical equipment is connected to the port, the program instructs the control circuit to A determination process for determining whether the output voltage of the second battery is higher than the output voltage of the first battery, If the determination process determines that the output voltage of the second battery is higher than the output voltage of the first battery, an output voltage adjustment process is performed to reduce the output voltage of the second battery to a value lower than the output voltage of the first battery by supplying power from the second battery to the electrical equipment while controlling the second battery connection state so that the positive electrode of the second battery is connected to the high-potential connection terminal via the neutral point, at least one of the windings, at least one of the upper reverse-conducting switching elements, and the high-potential wiring, and the negative electrode of the second battery is connected to the low-potential connection terminal. A program that executes something.

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