Electric circuit and program for output voltage adjustment

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 a 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 electric circuit disclosed in this specification is mounted on a vehicle. This electric circuit has 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 provided at one end thereof and a second connection terminal provided at the other end thereof. The second connection terminals of the three windings are connected to each other at the neutral point. 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 has a high-potential wiring, a 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 an external electrical equipment is connected to the port, the control circuit executes 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 reducing 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 in a state where 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.

[0006] In this specification, a reverse-conducting switching element is an element in which a switching element and a diode are connected in parallel, and the cathode of the diode is connected to the high-potential side terminal of the switching element while the anode of the diode is connected to the low-potential side 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. Further, the switching element and the diode may be provided on a common semiconductor substrate or on separate semiconductor substrates. In this specification, the "on" of the reverse-conducting switching element means the "on" of the switching element included in the reverse-conducting switching element, and the "off" of the reverse-conducting switching element means the "off" of the switching element included in the reverse-conducting switching element.

[0007] In this electric circuit, when the output voltage of the second battery is higher than the output voltage of the first battery, the output voltage adjustment process reduces the output voltage of the second battery to a value lower than the output voltage of the first battery. Therefore, when the first battery and the second battery are then connected in parallel, leakage current can be prevented.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] In an example of the above-described electric circuit, when the output voltage of the second battery decreases to a value lower than the output voltage of the first battery in the output voltage adjustment process, 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. While transferring power between the second battery and the electrical equipment, a parallel power transfer process may be executed to transfer power between the first battery and the electrical equipment in a state where the positive electrode of the first battery is connected to the high-potential connection terminal and the negative electrode of the first battery is connected to the low-potential connection terminal.

[0010] Note that the parallel power transfer process may be a process of supplying power from the first battery and the second battery to an external electrical equipment (that is, a process of discharging the first battery and the second battery), or a process of supplying power from the external electrical equipment to the first battery and the second battery (that is, a process of charging the first battery and the second battery).

[0011] In an example of the above-described electric circuit, when the output voltage of the second battery decreases to a value lower than the output voltage of the first battery in the output voltage adjustment process, the parallel power transfer process may be started in a state where the current flowing between the electric circuit and the electrical equipment is decreased.

[0012] According to this configuration, deterioration of a switch (for example, a relay switch) that connects the first battery to the port can be suppressed.

[0013] In an example of the above-described electric circuit, when it is determined in the determination process that the output voltage of the second battery is lower than the output voltage of the first battery, the parallel power transfer process may be executed.

[0014] In an example of the above-described electric circuit, the control circuit may execute the parallel power transfer process so that a state in which the output voltage of the second battery is lower than the output voltage of the first battery is maintained.

[0015] According to this configuration, leakage current can be prevented during the execution of the parallel power transfer process.

[0016] The electric circuit 10 of the embodiment shown in FIG. 1 is mounted on a vehicle. The electric 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 a traveling motor of the vehicle. The inverter circuit 30 converts 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. Thereby, the three-phase motor 40 rotates the drive wheels and the vehicle travels.

[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 the winding 44U. Terminals 41V and 42V are provided at both ends of the winding 44V. Terminals 41W and 42W are provided at both ends of the winding 44W. The terminals 42U, 42V, and 42W are connected to each other at the neutral point 46.

[0018] The inverter circuit 30 is connected to the 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 is composed of two reverse-conducting switching elements 35 connected in series between the high-potential wiring 31 and the low-potential wiring 32. Hereinafter, among 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 (for example, an insulated gate bipolar transistor or a field-effect transistor) and a diode (for example, 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 (that is, the collector or drain) of the switching element, and the anode of the diode is connected to the low-potential terminal (that is, the emitter or source) of the switching element.

[0019] The series switch circuit 34U is provided for 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 the 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 switches, the mutual connection relationship among 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 is changed.

[0026] The relay switch 81 is provided between the negative electrode of the first battery 11 and the positive electrode 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 provided between the negative electrodes of the first battery 11 and the second battery 12. When the relay switch 82 is turned on, the negative electrodes of the first battery 11 and the second battery 12 are connected.

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

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

[0030] The relay switch 85 is provided 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 provided 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 provided in series between the positive electrode of the second battery 12 and the neutral point wiring 50. Also, a relay switch 88 is provided on the neutral point wiring 50. When the relay switches 87 and 88 are turned on, the positive electrode of the second battery 12 is connected to the neutral point 46.

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

[0034] The control circuit 90 can execute a normal operation for driving the three-phase motor 40. In the normal operation, the control circuit 90 turns on the relay switches 81, 83, and 84 and turns off the 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. Therefore, the DC voltage output from 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 conduction switching element 35, and supplies the AC power to the three-phase motor 40. As a result, the three-phase motor 40 rotates. 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 the port 70. The control circuit 90 can perform a power transfer process for mutually transferring power between the electric circuit 10 and the external electrical equipment in a state where the external electrical equipment is connected to the port 70.

[0036] When power is transferred between the first battery 11 and external electrical equipment, the control circuit 90 forms a connection path shown by the arrow 100 in FIG. 1. That is, the control circuit 90 turns on the relay switches 82, 83, 84, 85, 86 and turns off the relay switch 81. In this state, the positive electrode of the first battery 11 is connected to the high-potential connection terminal 71 of the port 70 via the relay switches 83 and 86. Also, the negative electrode of the first battery 11 is connected to the low-potential connection terminal 72 of the port 70 via the relay switches 82, 84, and 85. When a voltage is applied to the port 70 in such a direction that the high-potential connection terminal 71 becomes higher in potential than the low-potential connection terminal 72 by the external electrical equipment in this state, a current flows through the path shown by the arrow 100 and the first battery 11 is charged. That is, the first battery charging process is executed. Also, when the external electrical equipment connects a device between the high-potential connection terminal 71 and the low-potential connection terminal 72 with the first battery 11 connected to the external electrical equipment, a current flows in the direction opposite to the arrow 100, and power is supplied from the first battery 11 to the external electrical equipment. That is, 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 a connection path shown by the arrow 102 in Fig. 1. That is, the control circuit 90 turns on the relay switches 84, 85, 86, 87, 88 and turns off the relay switch 81. Also, the control circuit 90 turns off the lower reverse conduction switching elements 35UL, 35VL, 35WL and turns on at least one of the upper reverse conduction switching elements 35UU, 35VU, 35WU. Note that the arrow 102 illustrates the path when the upper reverse conduction switching element 35VU is turned on. In this state, the positive electrode of the second battery 12 is connected to the high-potential connection terminal 71 of the port 70 via the relay switches 87, 88, the neutral point 46, the winding 44V, the upper reverse conduction switching element 35VU, and the relay switch 86. Also, the negative electrode of the second battery 12 is connected to the low-potential connection terminal 72 of the port 70 via the relay switches 84, 85. When a voltage is applied to the port 70 in such a direction that the high-potential connection terminal 71 becomes higher in potential than the low-potential connection terminal 72 by the external electrical equipment in this state, current flows through the path shown by the arrow 102 and the second battery 12 is charged. That is, the second battery charging process is executed. Note that when charging the second battery 12, the upper reverse conduction switching element may be periodically switched. 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 with the second battery 12 connected to the external electrical equipment, current flows in the direction opposite to the 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 executed. Note that in the second battery power supply process, since current flows through the diode of the upper reverse conduction switching element, the switching element of the upper reverse conduction switching element may be off.

[0038] As described 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] In addition, the control circuit 90 can connect the first battery 11 and the second battery 12 in parallel to the port 70 through the paths indicated by the arrows 100 and 102. When the first battery 11 and the second battery 12 are connected in parallel to the port 70, a process of simultaneously executing the first battery charging process and the second battery charging process (hereinafter referred to as the parallel charging process) can be performed, and a process of simultaneously executing the first battery power supply process and the second battery power supply process (hereinafter referred to as the parallel power supply process) can be performed. Further, the control circuit 90 can perform a process of selectively executing the parallel charging process and the parallel power supply process according to the situation in a state where the first battery 11 and the second battery 12 are connected in parallel to the port 70 (hereinafter referred to as the parallel charge and power supply process).

[0040] When the first battery 11 and the second battery 12 are connected in parallel in a state where the output voltage V2 of the second battery 12 is higher than the output voltage V1 of the first battery 11, a leakage current flows from the second battery 12 to the first battery 11 through the path indicated by the arrow 104 in FIG. 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 voltage is applied in the forward direction to the diodes of the upper reverse-conducting switching elements 35UU, 35VU, and 35WU, so these diodes turn on. For this reason, a leakage current flows from the positive electrode of the second battery 12 to the positive electrode of the first battery 11 through the relay switches 87, 88, the neutral point 46, the windings 44U, 44V, 44W, the diodes of the upper reverse-conducting switching elements 35UU, 35VU, 35WU, and the relay switch 83. Note that the arrow 104 illustrates a path passing through the diode of the upper reverse-conducting switching element 35VU. Since there is no load that consumes power on the path through which the leakage current flows, the leakage current becomes a relatively large current. For this reason, when the leakage current flows, the first battery 11 and the second battery 12 deteriorate.

[0041] In order to execute the power transfer process while preventing leakage current, the control circuit 90 executes the process shown in FIG. 3. When an external electrical facility is connected to the port 70, the control circuit 90 executes the process shown in FIG. 3 according to the program stored in the memory. At the start of the process in FIG. 3, the vehicle is stopped, and the relay switches 81 to 88 and all the reverse conduction 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 the relay switches 82, 83, 84 and detect the output voltage V1 of the first battery 11 by the voltmeter 37. Also, for example, the control circuit 90 can turn on the relay switches 84, 87 and detect the output voltage V2 of the second battery 12 by the voltmeter 61. In step S2, no current is flowing through the batteries 11, 12. Therefore, the output voltages V1 and V2 detected in step S2 are the OCV (Open Circuit Voltage). The control circuit 90 determines whether the output voltage V2 is higher than the output voltage V1.

[0042] When the output voltage V2 is less than or equal to the output voltage V1 (that is, NO in step S2), the control circuit 90 executes the parallel charging process in step S14. When the output voltage V2 is less than or equal to the output voltage V1, no leakage current will occur even if the first battery 11 and the second battery 12 are connected in parallel. Therefore, the parallel charging process can be appropriately executed in step S14.

[0043] When the output voltage V2 is higher than the output voltage V1 (i.e., when the answer in step S2 is YES), the control circuit 90 executes the second battery power supply process in step S4. That is, the control circuit 90 connects the second battery 12 to the port 70 through the path shown by the arrow 102 in FIG. 1 and commands to execute a power supply operation to the external electrical equipment. Therefore, a current flows in the reverse direction of the arrow 102 in FIG. 1, and power is supplied from the second battery 12 to the external electrical equipment. In this way, in step S4, since the second battery 12 is discharged, the output voltage V2 of the second battery 12 gradually decreases. Also, in step S4, the control circuit 90 shuts off the relay switches 82 and 83 to disconnect the first battery 11 from the port 70. Therefore, in step S4, the output voltage V1 of the first battery 11 does not change.

[0044] After step S4 is performed 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, since the output voltage V1 of the first battery 11 does not change in step S4, the output voltage V1 measured in step S2 can be used as a comparison value in step S6. Also, the control circuit 90 measures the output voltage V2 in step S6. Here, the control circuit 90 may measure the output voltage V2 (i.e., CCV (Closed Circuit Voltage)) while a current is flowing through the second battery 12, or may measure the output voltage V2 (i.e., OCV) after stopping the current of the second battery 12. The control circuit 90 repeats steps S4 and S6 until the output voltage V2 becomes less than or equal to the output voltage V1. While steps S4 and S6 are repeated, the output voltage V2 decreases until it becomes less than or equal to the output voltage V1. In this way, by steps S4 and S6, the output voltage V2 is adjusted so that the output voltage V2 becomes less than or equal to the output voltage V1. When the output voltage V2 becomes less than or equal to 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 it can limit the charging / discharging current of the external electrical equipment (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 it can reduce the charging / discharging current from the current value. This determination is made based on the type of the external electrical equipment, the operating state of the external electrical equipment, etc. If the charging / discharging current cannot be limited, the control circuit 90 executes the charging / discharging 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 and disconnects the first battery 11 from port 70. The control circuit 90 repeats steps S8 and S10 until the charging / discharging current can be limited by the external electrical equipment. Note that if the charging / discharging current cannot be limited by the external electrical equipment, steps S8 and S10 are continued until the end of the power transfer process.

[0046] When the charging / discharging current can be limited by the 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 / discharging current. Thereafter, the control circuit 90 starts the parallel charging / discharging process of step S14 by turning on the relay switches 82 and 83. In this way, since the control circuit 90 turns on the relay switches 82 and 83 with the charging / discharging current reduced, it is possible to prevent a high inrush current from flowing through the relay switches 82 and 83. Thereby, sticking of the relay switches 82 and 83 can be prevented. When the control circuit 90 starts step S14, it releases the limitation of the charging / discharging current. As a result, the parallel charging / discharging process can be executed with a high charging / discharging current.

[0047] In the parallel charging operation of step S14, the control circuit 90 controls the current flowing through each battery so that the state where the output voltage V1 is higher than the output voltage V2 is maintained. 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. Thereby, it is possible to prevent the output voltage V2 from becoming higher than the output voltage V1. Therefore, it is possible to prevent the generation of leakage current during the execution of step S14.

[0048] As described above, according to the electric circuit 10 of the embodiment, it is possible to execute the power transfer process while preventing the generation of leakage current.

[0049] In the embodiment, the second battery charging / discharging process is executed in step S10, but only one of the second battery charging process or the second battery discharging process may be executed.

[0050] Further, step S14 of the embodiment is an example of the parallel power transfer process. In the embodiment, the parallel charging / discharging process is executed as the parallel power transfer process, but only one of the parallel charging process or the parallel discharging process may be executed as the parallel power transfer process.

[0051] Although the embodiments have been described in detail above, 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 utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Also, the technology illustrated in this specification or the drawings achieves a plurality of purposes simultaneously, and has technical utility by achieving one of those purposes itself.

Explanation of Reference Numerals

[0052] 11: First battery 12: Second battery 30: Inverter circuit 31: High potential wiring 32: Low potential wiring 34U~34W: Series switch circuit 40: Three-phase motor 46: Neutral point 70: Port

Claims

1. An electric circuit mounted on a vehicle, a first battery, a second battery, a three-phase motor having three windings of a U-phase winding, a V-phase winding, and a W-phase winding, each of the three windings having a first connection terminal provided at one end thereof and a second connection terminal provided at the other end thereof, 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 a high-potential connection terminal and a low-potential connection terminal, a control circuit, and having, wherein the inverter circuit has a high-potential wiring, a low-potential wiring, and three series switch circuits provided for each of the three windings, and having, each of the series switch circuits having 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 an external electrical equipment is connected to the port, the control circuit performs a determination process of determining whether the output voltage of the second battery is higher than the output voltage of the first battery, and when it is determined in the determination process that the output voltage of the second battery is higher than the output voltage of the first battery, the positive electrode of the second battery is connected to the high-potential connection terminal through 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, and power is supplied from the second battery to the electrical equipment, thereby reducing the output voltage of the second battery to a value lower than the output voltage of the first battery. An output voltage adjustment process, An electric circuit that executes.

2. When the output voltage of the second battery decreases to a value lower than the output voltage of the first battery in the output voltage adjustment process, 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. While transferring power between the second battery and the electrical equipment, and while the positive electrode of the first battery is connected to the high-potential connection terminal and the negative electrode of the first battery is connected to the low-potential connection terminal, performing a parallel power transfer process of transferring power between the first battery and the electrical equipment. The electrical circuit according to claim 1.

3. When the output voltage of the second battery decreases to a value lower than the output voltage of the first battery in the output voltage adjustment process, the control circuit starts the parallel power transfer process in a state where the current flowing between the electrical circuit and the electrical equipment is reduced. The electrical circuit according to claim 2.

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

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

6. A program executed by an electrical circuit mounted on a vehicle, wherein the electrical circuit has a first battery, a second battery, 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 provided at one end and a second connection terminal provided at the other end. A three-phase motor in which the second connection terminals of the three windings are 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 a high-potential connection terminal and a low-potential connection terminal, a control circuit, and has wherein the inverter circuit has a high-potential wiring, a low-potential wiring, and three series switch circuits provided for each of the three windings, and has Each of the series switch circuits includes an upper reverse conduction switching element, which is a reverse conduction switching element connected between the first connection terminal of the corresponding winding and the high potential wiring, and a lower reverse conduction switching element, which is a reverse conduction switching element connected between the first connection terminal of the corresponding winding and the low potential wiring. When an external electrical facility is connected to the port, the program causes the control circuit to perform a determination process for determining whether the output voltage of the second battery is higher than the output voltage of the first battery, when it is determined in the determination process that the output voltage of the second battery is higher than the output voltage of the first battery, in a state where 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 conduction switching elements, and the high potential wiring, and the negative electrode of the second battery is connected to the low potential connection terminal, by supplying power from the second battery to the electrical facility, an output voltage adjustment process for reducing the output voltage of the second battery to a value lower than the output voltage of the first battery. A program that causes the above to be executed.

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