Electrical circuit and program for adjusting output voltage

Abstract

The invention provides an electric circuit and an output voltage adjusting program. The electric circuit installed in a vehicle includes a first battery, a second battery, a three-phase motor, an inverter circuit, a port, and a control circuit. When an external electrical device is connected to the port, the control circuit executes an output voltage adjustment process if it is determined that the output voltage of the second battery is higher than the output voltage of the first battery.

Description

Technical Field

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

[0002] Japanese Patent Application Laid-Open No. 2020-120566 discloses an electrical circuit mounted on a vehicle. The electrical circuit has a series circuit of two storage batteries, a converter circuit, and a three-phase motor. The converter circuit drives the three-phase motor by converting DC power supplied from the series circuit of the storage batteries into AC power and supplying it to the three-phase motor. Further, the electrical circuit has a wiring connecting the connection point of the two storage batteries to the neutral point of each coil of the three-phase motor. By transmitting power between the two storage batteries via this wiring, each storage battery can be heated. Summary of the Invention

[0003] In an electrical circuit having a first storage battery, a second storage battery, a converter circuit, and a three-phase motor, there is a technology for transmitting power between each storage battery and an electrical device outside the vehicle. The first storage battery is connected to the electrical device via a wiring. The second storage battery is connected to the electrical device via the converter circuit and the three-phase motor. With this configuration, the two storage batteries can be connected in parallel to the external electrical device. In such an electrical circuit, if the output voltage of the second storage battery is higher than the output voltage of the first storage battery, when the first storage battery and the second storage battery are connected in parallel, sometimes current (hereinafter referred to as leakage current) flows from the second storage battery to the first storage battery through a diode in the converter circuit. When the leakage current flows, the first storage battery and the second storage battery deteriorate. In this specification, a technology for adjusting the output voltage of the storage battery is proposed.

[0004] The electrical circuit disclosed in this specification is mounted on a vehicle. The electrical circuit has a first storage battery, a second storage battery, a three-phase motor, a converter circuit, a port, and a control circuit.

[0005] The three-phase motor has three windings, namely 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. The second connection terminals of the three windings are connected to each other at the neutral point.

[0006] The converter 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.

[0007] The port has a high-potential connection terminal and a low-potential connection terminal. The converter circuit has a high-potential wiring, a low-potential wiring, and three series switch circuits respectively provided for each of the three windings. Each of the series switch circuits has an upper-side reverse-conducting switch element, which is a reverse-conducting switch element connected between the first connection terminal of the corresponding winding and the high-potential wiring, and a lower-side reverse-conducting switch element, which is a reverse-conducting switch element connected between the first connection terminal of the corresponding winding and the low-potential wiring. When an external electrical device 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 as follows: 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, power is supplied from the second battery to the electrical device 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-side reverse-conducting switch elements, and the high-potential wiring, and the negative electrode of the second battery is connected to the low-potential connection terminal, thereby reducing the output voltage of the second battery to a value lower than the output voltage of the first battery.

[0008] It should be noted that, in this specification, the reverse-conducting switch element is an element in which a switch element and a diode are connected in parallel, and refers to an element in which the cathode of the diode is connected to the high-potential side terminal of the switch element and the anode of the diode is connected to the low-potential side terminal of the switch element. It should be noted that the switch element can also be a semiconductor switch element such as a field-effect transistor or an insulated-gate bipolar transistor. The diode can be either a pn diode or a Schottky barrier diode. Moreover, the switch element and the diode can be provided on a common semiconductor substrate or on different semiconductor substrates. And, in this specification, the turning on of the reverse-conducting switch element means the turning on of the switch element included in the reverse-conducting switch element, and the turning off of the reverse-conducting switch element means the turning off of the switch element included in the reverse-conducting switch element.

[0009] In this electrical circuit, when the output voltage of the second battery is higher than the output voltage of the first battery, the output voltage of the second battery is reduced to a value lower than the output voltage of the first battery through the output voltage adjustment process. Therefore, leakage current can be prevented when the first battery and the second battery are connected in parallel later. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The features, advantages, technology, and industrial significance of the embodiments of the present invention are described as follows with reference to the accompanying drawings, in which the same reference numerals denote the same elements.

[0011] Figure 1 is a circuit diagram of an electrical circuit (a diagram showing the connection paths to the first battery and the second battery).

[0012] Figure 2 is a circuit diagram of an electrical circuit (a diagram showing the path of the leakage current).

[0013] Figure 3 is a flowchart showing the processing executed by the control circuit. Detailed Description

[0014] In an example of the above electrical circuit, it is possible that when the output voltage of the second battery drops to a value lower than the output voltage of the first battery in the output voltage adjustment process, the control circuit executes the following parallel power transmission process: power is transmitted between the second battery and the electrical device 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-side 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 transmitted between the first battery and the electrical device 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.

[0015] It should be noted that the parallel power transmission process can be either a process of supplying power from the first battery and the second battery to an external electrical device (a process of discharging the first battery and the second battery), or a process of supplying power from an external electrical device to the first battery and the second battery (a process of charging the first battery and the second battery).

[0016] In an example of the above electrical circuit, it is possible that when the output voltage of the second battery drops 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 transmission process while reducing the current flowing between the electrical circuit and the electrical device.

[0017] According to this structure, deterioration of the switch (such as a relay switch) connecting the first battery to the port can be suppressed.

[0018] In an example of the above electrical circuit, it is possible that 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, the control circuit executes the parallel power transmission process.

[0019] In an example of the above-described electrical circuit, it is possible that the control circuit performs the parallel power transmission process in such a manner as to maintain the output voltage of the second battery lower than the output voltage of the first battery.

[0020] According to this configuration, leakage current can be prevented during the execution of the parallel power transmission process.

[0021] Figure 1 The electrical circuit 10 of the illustrated embodiment is mounted on a vehicle. The electrical circuit 10 includes a first battery 11, a second battery 12, a converter circuit 30, and a three-phase motor 40. The three-phase motor 40 is a driving motor for the vehicle. The converter 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.

[0022] 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.

[0023] The converter circuit 30 is connected to the terminals 41U, 41V, and 41W of the three-phase motor 40. The converter circuit 30 includes a high-potential wiring 31, a low-potential wiring 32, and three series switch circuits 34U, 34V, and 34W. The series switch circuits 34U, 34V, and 34W are each composed of two reverse-conducting switch elements 35 connected in series between the high-potential wiring 31 and the low-potential wiring 32. Hereinafter, the reverse-conducting switch element connected to the high-potential wiring 31 among the two reverse-conducting switch elements 35 connected in series may be referred to as the upper-side reverse-conducting switch element, and the reverse-conducting switch element connected to the low-potential wiring 32 may be referred to as the lower-side reverse-conducting switch element. Each reverse-conducting switch element 35 has a configuration in which a switch 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 reverse parallel. In each reverse-conducting switch element 35, the cathode of the diode is connected to the high-potential terminal (i.e., the collector or the drain) of the switch element, and the anode of the diode is connected to the low-potential terminal (i.e., the emitter or the source) of the switch element.

[0024] The series switching circuit 34U is provided relative to the winding 44U. The series switching 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.

[0025] The series switching circuit 34V is provided relative to the winding 44V. The series switching circuit 34V has an upper reverse-conducting switching element 35VU and a lower reverse-conducting switching element 35VL. The high-potential terminal of the upper reverse-conducting switching element 35VU is connected to the high-potential wiring 31. The low-potential terminal of the upper reverse-conducting switching element 35VU and the high-potential terminal of the lower reverse-conducting switching element 35VL are connected to the terminal 41V. The low-potential terminal of the lower reverse-conducting switching element 35VL is connected to the low-potential wiring 32.

[0026] The series switching circuit 34W is provided relative to the winding 44W. The series switching circuit 34W has an upper reverse-conducting switching element 35WU and a lower reverse-conducting switching element 35WL. The high-potential terminal of the upper reverse-conducting switching element 35WU is connected to the high-potential wiring 31. The low-potential terminal of the upper reverse-conducting switching element 35WU and the high-potential terminal of the lower reverse-conducting switching element 35WL are connected to the terminal 41W. The low-potential terminal of the lower reverse-conducting switching element 35WL is connected to the low-potential wiring 32.

[0027] 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.

[0028] 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.

[0029] The electrical circuit 10 has a port 70. A connector of an electrical device outside the vehicle (hereinafter referred to as an external electrical device) can be connected to the port 70. The port 70 has a high-potential connection terminal 71 and a low-potential connection terminal 72.

[0030] The electrical circuit 10 has a plurality of relay switches 81 to 88. By switching each relay switch, 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.

[0031] A relay switch 81 is arranged between the negative electrode of the first storage battery 11 and the positive electrode of the second storage battery 12. When the relay switch 81 is turned on, the first storage battery 11 and the second storage battery 12 are connected in series.

[0032] A relay switch 82 is arranged between the negative electrode of the first storage battery 11 and the negative electrode of the second storage battery 12. When the relay switch 82 is turned on, the negative electrode of the first storage battery 11 is connected to the negative electrode of the second storage battery 12.

[0033] An ammeter 20 and a relay switch 83 are arranged in series between the positive electrode of the first storage battery 11 and the high-potential wiring 31. When the relay switch 83 is turned on, the positive electrode of the first storage battery 11 is connected to the high-potential wiring 31.

[0034] A relay switch 84 is arranged between the negative electrode of the second storage battery 12 and the low-potential wiring 32. When the relay switch 84 is turned on, the negative electrode of the second storage battery 12 is connected to the low-potential wiring 32.

[0035] A relay switch 85 is arranged 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.

[0036] A relay switch 86 is arranged 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.

[0037] An ammeter 52 and a relay switch 87 are arranged in series between the positive electrode of the second storage battery 12 and the neutral-point wiring 50. And a relay switch 88 is arranged on the neutral-point wiring 50. When the relay switches 87 and 88 are turned on, the positive electrode of the second storage battery 12 is connected to the neutral point 46.

[0038] The electrical circuit 10 has a control circuit 90. The control circuit 90 is composed of a CPU, a memory, etc. A program for controlling the electrical circuit 10 is stored in the memory of the control circuit 90. The memory is an example of a storage medium. The control circuit 90 controls the switching elements of each reverse-conducting switching element 35 and the relay switches 81 to 88 according to the program. And the control circuit 90 can communicate with an external electrical device when the external electrical device is connected to the port 70.

[0039] The control circuit 90 can perform a normal operation to drive 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 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 switch element 35 and supplies the AC power to the three-phase motor 40. Thereby, 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.

[0040] As described above, an external electrical device is connected to the port 70. The control circuit 90 can perform a power transfer process of mutually transferring power between the electrical circuit 10 and the external electrical device in a state where the external electrical device is connected to the port 70.

[0041] When power is transferred between the first battery 11 and the external electrical device, the control circuit 90 forms Figure 1 the connection path shown by the arrow 100. That is, the control circuit 90 turns on the relay switches 82, 83, 84, 85, and 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. And, 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 the external electrical device applies a voltage to the port 70 in a direction where the high-potential connection terminal 71 is at a higher potential than the low-potential connection terminal 72 in this state, current flows along the path shown by the arrow 100, and the first battery 11 is charged. That is, the first battery charging process is executed. And, when the external electrical device connects a device between the high-potential connection terminal 71 and the low-potential connection terminal 72 in a state where the first battery 11 is connected to the external electrical device, current flows in the direction opposite to the arrow 100, and power is supplied from the first battery 11 to the external electrical device. That is, the first battery power supply process is executed.

[0042] When power is transferred between the second battery 12 and the external electrical device, the control circuit 90 forms Figure 1The connection path indicated by arrow 102. That is, the control circuit 90 turns on the relay switches 84, 85, 86, 87, 88 and turns off the relay switch 81. Further, the control circuit 90 turns off the lower-side reverse-conducting switching elements 35UL, 35VL, 35WL and turns on at least one of the upper-side reverse-conducting switching elements 35UU, 35VU, 35WU. It should be noted that arrow 102 illustrates the path in the case where the upper-side reverse-conducting 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-side reverse-conducting switching element 35VU, and the relay switch 86. And 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 by an external electrical device in such a direction that the high-potential connection terminal 71 is at a higher potential than the low-potential connection terminal 72 in this state, current flows along the path indicated by arrow 102, and the second battery 12 is charged. That is, the second battery charging process is executed. It should be noted that during the charging of the second battery 12, the upper-side reverse-conducting switching element may also be switched periodically. In this case, the converter circuit 30 and the windings of the three-phase motor 40 operate as a buck converter circuit, and the charging current with respect to the second battery 12 can be suppressed. And when the external electrical device connects the device between the high-potential connection terminal 71 and the low-potential connection terminal 72 in a state where the second battery 12 is connected to the external electrical device, current flows in the direction opposite to arrow 102, and power is supplied from the second battery 12 to the external electrical device. That is, the second battery power supply process is executed. It should be noted that in the second battery power supply process, since current flows through the diode of the upper-side reverse-conducting switching element, the switching element of the upper-side reverse-conducting switching element may also be turned off.

[0043] As described above, the power transmission 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.

[0044] Further, the control circuit 90 can connect the first storage battery 11 and the second storage battery 12 in parallel to the port 70 along the paths indicated by the arrows 100 and 102. When the first storage battery 11 and the second storage battery 12 are connected in parallel to the port 70, a process of simultaneously performing the first storage battery charging process and the second storage battery charging process (hereinafter referred to as parallel charging process) can be performed, and a process of simultaneously performing the first storage battery power supply process and the second storage battery power supply process (hereinafter referred to as parallel power supply process) can be performed. Further, in a state where the control circuit 90 connects the first storage battery 11 and the second storage battery 12 in parallel to the port 70, a process of selectively performing the parallel charging process and the parallel power supply process according to the situation (hereinafter referred to as parallel charging and power supply process) can be performed.

[0045] When the first storage battery 11 and the second storage battery 12 are connected in parallel in a state where the output voltage V2 of the second storage battery 12 is higher than the output voltage V1 of the first storage battery 11, the leakage current flows from the second storage battery 12 to the first storage battery 11 along the path indicated by the arrow 104 in Figure 2 That is, when the output voltage V2 of the second storage battery 12 is higher than the output voltage V1 of the first storage battery 11, a voltage is applied in the forward direction to each diode of the upper-side reverse-conducting switching elements 35UU, 35VU, and 35WU, so these diodes are turned on. Therefore, the leakage current flows from the positive electrode of the second storage battery 12 through the relay switches 87 and 88, the neutral point 46, the windings 44U, 44V, and 44W, each diode of the upper-side reverse-conducting switching elements 35UU, 35VU, and 35WU, and the relay switch 83 to the positive electrode of the first storage battery 11. It should be noted that the arrow 104 illustrates the path through the diode of the upper-side reverse-conducting switching element 35VU. Since there is no power-consuming load in the path where the leakage current flows, the leakage current is a relatively large current. Therefore, when the leakage current flows, the first storage battery 11 and the second storage battery 12 deteriorate.

[0046] The control circuit 90 performs the process shown in Figure 3 in order to prevent the leakage current and perform the power transmission process. When an external electrical device is connected to the port 70, the control circuit 90 performs the process shown in Figure 3 according to the program stored in the memory. In Figure 3At the start of the processing, the vehicle stops, and the relay switches 81 to 88 and all the reverse-conducting switch elements 35 are turned off. In 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, and 84 and detect the output voltage V1 of the first battery 11 through the voltmeter 37. And, for example, the control circuit 90 can turn on the relay switches 84 and 87 and detect the output voltage V2 of the second battery 12 through the voltmeter 61. In S2, no current flows to the batteries 11 and 12. Therefore, the output voltages V1 and V2 detected in S2 are open-circuit voltages (OCV: Open Circuit Voltage). The control circuit 90 determines whether the output voltage V2 is higher than the output voltage V1.

[0047] When the output voltage V2 is equal to or lower than the output voltage V1 (i.e., when the answer in S2 is no), the control circuit 90 performs parallel charging power supply processing in S14. When the output voltage V2 is equal to or lower than the output voltage V1, even if the first battery 11 and the second battery 12 are connected in parallel, no leakage current is generated, so the parallel charging power supply processing can be appropriately performed in S14.

[0048] When the output voltage V2 is higher than the output voltage V1 (i.e., when the answer in S2 is yes), the control circuit 90 performs second battery power supply processing in S4. That is, the control circuit 90 issues an instruction in such a way that the second battery 12 is connected to the port 70 along the path indicated by the arrow 102 in Figure 1 and a power supply operation is performed for the external electrical device. Therefore, current flows in the opposite direction of the arrow 102 in Figure 1 and power is supplied from the second battery 12 to the external electrical device. Thus, in S4, the second battery 12 discharges, so the output voltage V2 of the second battery 12 gradually decreases. And, in S4, the control circuit 90 disconnects the first battery 11 from the port 70 by turning off the relay switches 82 and 83. Therefore, in S4, the output voltage V1 of the first battery 11 remains unchanged.

[0049] After a predetermined time of S4 has elapsed, the control circuit 90 executes S6. In 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 storage battery 11 does not change in S4, so in S6, the output voltage V1 measured in S2 can be used as the value for comparison. Also, the control circuit 90 measures the output voltage V2 in S6. Here, the control circuit 90 can measure the output voltage V2 (i.e., the closed circuit voltage (CCV)) in a state where current is flowing to the second storage battery 12, or can stop the current of the second storage battery 12 and measure the output voltage V2 (i.e., OCV). The control circuit 90 repeats S4 and S6 until the output voltage V2 becomes equal to or lower than the output voltage V1. During the repetition of S4 and S6, the output voltage V2 drops to be equal to or lower than the output voltage V1. In this way, through S4 and S6, the output voltage V2 is adjusted so that the output voltage V2 becomes equal to or lower than the output voltage V1. When the output voltage V2 becomes equal to or lower than the output voltage V1, the control circuit 90 determines "no" in S6 and executes S8.

[0050] In S8, the control circuit 90 determines whether it is possible to limit the charging power supply current (i.e., the current flowing between the electrical circuit 10 and the external electrical device via the port 70) in the external electrical device. That is, the control circuit 90 determines whether it is possible to decrease the charging power supply current from the current value. This determination is made based on the model of the external electrical device, the operating state of the external electrical device, and the like. In the case where the charging power supply current cannot be limited, the control circuit 90 uses the second storage battery 12 to execute the charging power supply process in S10. That is, the control circuit 90 selectively executes the second storage battery charging process and the second storage battery power supply process. Also, in S10, the control circuit 90 opens the relay switches 82 and 83 to disconnect the first storage battery 11 from the port 70. The control circuit 90 repeats S8 and S10 until it becomes possible to limit the charging power supply current in the external electrical device. It should be noted that in the case where the charging power supply current cannot be limited in the external electrical device, S8 and S10 are continued until the end of the power transmission process.

[0051] When the charging and power supply current can be limited in an external electrical device, the control circuit 90 determines yes in S8 and executes S12. In S12, the control circuit 90 issues an instruction to the external electrical device to limit the charging and power supply current. Then, the control circuit 90 starts the parallel charging and power supply process of 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 while the charging and power supply current is decreasing, it is possible to prevent a high inrush current from flowing through the relay switches 82 and 83. As a result, it is possible to prevent the fastening of the relay switches 82 and 83. When starting S14, the control circuit 90 releases the limitation of the charging and power supply current. Thus, it is possible to execute the parallel charging and power supply process with a high charging and power supply current.

[0052] In the parallel charging and power supply operation of S14, the control circuit 90 controls the current flowing through each storage battery so as to maintain the state where the output voltage V1 is 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-conducting switching elements 35UU, 35VU, and 35WU to limit the charging current with respect to the second storage battery 12. As a result, 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 S14.

[0053] As described above, according to the electrical circuit 10 of the embodiment, it is possible to prevent the generation of leakage current and execute the power transmission process.

[0054] Note that, in the embodiment, the second storage battery charging and power supply process is executed in S10, but it is also possible to execute only one of the second storage battery charging process and the second storage battery power supply process.

[0055] Moreover, S14 of the embodiment is an example of the parallel power transmission process. Note that, in the embodiment, as the parallel power transmission process, the parallel charging and power supply process is executed, but it is also possible to execute only one of the parallel charging process and the parallel power supply process as the parallel power transmission process.

[0056] As described above, the embodiment has been described in detail, but these are merely examples and do not limit the claims. The technology described in the claims includes technical solutions obtained by various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or through various combinations, and are not limited to the combinations recited in the claims at the time of application. Moreover, the technology illustrated in this specification or the drawings can achieve multiple purposes simultaneously, and achieving one of the purposes itself also has technical utility.

Claims

1. An electric circuit, the electric circuit being an electric circuit mounted on a vehicle, The electrical circuit comprises: First battery; Second battery; A three-phase motor, wherein the three-phase motor has three windings, namely, a U-phase winding, a V-phase winding and a W-phase winding, wherein the three windings respectively have a first connection terminal provided at one end and a second connection terminal provided at the other end, and the second connection terminals of the three windings are connected to each other at a neutral point; a converter 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; as well as control circuit, where The converter circuit includes a high potential wiring, a low potential wiring, and three series switch circuits provided for each of the three windings. The series switch circuits each include an upper reverse conducting switch element and a lower reverse conducting switch element, wherein the upper reverse conducting switch element is a reverse conducting switch element connected between the first connection terminal of the corresponding winding and the high potential wiring, and the lower reverse conducting switch element is a reverse conducting switch element connected between the first connection terminal of the corresponding winding and the low potential wiring. The control circuit performs a determination process for determining whether the output voltage of the second battery is higher than the output voltage of the first battery when an external electrical device is connected to the port. When the control circuit determines in the determination process that the output voltage of the second battery is higher than the output voltage of the first battery, the control circuit performs the following output voltage adjustment process: 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, 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.

2. The electrical circuit according to claim 1, wherein: 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, the control circuit performs the following parallel power transmission process: power is transmitted between the second battery and the electrical device 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, and power is transmitted between the first battery and the electrical device 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.

3. The electrical circuit according to claim 2, wherein: When the output voltage of the second storage battery drops to a value lower than the output voltage of the first storage battery during the output voltage adjustment process, the control circuit starts the parallel power transmission process while reducing the current flowing between the electric circuit and the electric device.

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

5. The electrical circuit according to claim 2 or 3, wherein: The control circuit executes the parallel power transmission process so that the output voltage of the second storage battery is maintained lower than the output voltage of the first storage battery.

6. A program for adjusting output voltage, the program for adjusting output voltage being a program executed by an electrical circuit mounted on a vehicle, wherein: The electrical circuit has: First battery; Second battery; A three-phase motor, wherein the three-phase motor has three windings, namely, a U-phase winding, a V-phase winding and a W-phase winding, wherein the three windings respectively have a first connection terminal provided at one end and a second connection terminal provided at the other end, and the second connection terminals of the three windings are connected to each other at a neutral point; a converter 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; as well as Control circuit, The converter circuit includes a high potential wiring, a low potential wiring, and three series switch circuits provided for each of the three windings. The series switch circuits each include an upper reverse conducting switch element and a lower reverse conducting switch element, wherein the upper reverse conducting switch element is a reverse conducting switch element connected between the first connection terminal of the corresponding winding and the high potential wiring, and the lower reverse conducting switch element is a reverse conducting switch element connected between the first connection terminal of the corresponding winding and the low potential wiring. The program causes the control circuit to execute a determination process for determining whether the output voltage of the second storage battery is higher than the output voltage of the first storage battery when an external electrical device is connected to the port. The program performs the following output voltage adjustment processing when it is determined in the determination processing that the output voltage of the second battery is higher than the output voltage of the first battery: the output voltage of the second battery is reduced 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 controlled to be a second battery connection state, wherein the second battery connection state is a state in which 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.

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