Electronic circuit and program product for parallel charging start processing

Abstract

The invention relates to an electronic circuit and a program product for parallel charge start processing. A parallel charging start process for an electronic circuit mounted on a vehicle includes: a process for discharging a high-voltage capacitor via an inverter circuit and a three-phase motor in a state in which a connection switching circuit is controlled so that application of voltage to the high-voltage capacitor from a series circuit of a first battery and a second battery is stopped; a process of applying an output voltage of the first battery to the high-voltage capacitor to charge the high-voltage capacitor; and controlling the connection switching circuit such that the first battery is connected between the high-potential wiring and the low-potential wiring, the second battery is connected between the neutral point and the low-potential wiring, and a charging voltage generated by power supplied from an external charging device is applied between the high-potential wiring and the low-potential wiring. And a process of charging the first battery and the second battery in parallel.

Description

Technical Field

[0001] The technology disclosed in this specification relates to an electronic circuit and a program product for parallel charging start processing. Background Art

[0002] An electronic circuit mounted on a vehicle is disclosed in Japanese Unexamined Patent Application Publication No. 2020-120566. The electronic circuit has a series circuit of two 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 batteries into AC power and supplying it to the three-phase motor. In addition, the electronic circuit has a wiring that connects the connection point of the two batteries to the neutral point of each coil of the three-phase motor. By transferring power between the two batteries via this wiring, each battery can be heated. Summary of the Invention

[0003] A capacitor (hereinafter referred to as a high-voltage capacitor) is provided between the high-potential wiring and the low-potential wiring of the converter circuit. In addition, in an electronic circuit in which a wiring is connected to the neutral point of the three-phase motor, a capacitor (hereinafter referred to as a low-voltage capacitor) is sometimes connected between the neutral point and the low-potential wiring. In such an electronic circuit, there is a case where a process of parallel charging each battery by an external charging device is performed while the output voltage of the series circuit of the two batteries is being applied to the high-voltage capacitor. In this case, in the existing process, first, the high-voltage capacitor and the low-voltage capacitor are discharged. Then, the high-voltage capacitor is connected to one battery, and the low-voltage capacitor is connected to the other battery. Then, the supply voltage of the external charging device is applied in parallel to each battery to charge each battery. According to this process, the voltage of each capacitor can be adjusted to an appropriate voltage corresponding to the battery, and a surge current can be prevented from being generated from the high-voltage capacitor when the circuit connection is changed. However, in this process, there is a problem that the time required for changing the circuit connection is long. Therefore, it is possible to generate a timeout error exceeding the waiting acceptance time of the external charging device. In this specification, a technology that can start parallel charging of the battery in a shorter time is proposed.

[0004] The electronic circuit disclosed in this specification is mounted on a vehicle. The electronic circuit has: A first battery; A second battery; A high-voltage capacitor; A low-voltage capacitor; A three-phase motor; a converter circuit; a charging interface; a connection switching circuit; and a control circuit. 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, and the second connection terminals of the three windings are connected to each other at the neutral point. 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. The charging interface is connected to an external charging device. The connection switching circuit changes the mutual connections among the first battery, the second battery, the converter circuit, the neutral point, and the charging interface. The converter circuit includes: A high-potential wiring; A low-potential wiring; and Three series switch circuits respectively provided for the three windings. Each of the series switch circuits includes: an upper reverse-conducting switch element serving as a reverse-conducting switch element that connects between the first connection terminal of the corresponding winding and the high-potential wiring; and a lower reverse-conducting switch element serving as a reverse-conducting switch element that connects between the first connection terminal of the corresponding winding and the low-potential wiring. The high-voltage capacitor is connected between the high-potential wiring and the low-potential wiring. The low-voltage capacitor is connected between the neutral point and the low-potential wiring. When an external charging device is connected to the charging interface during the execution of the series operation of controlling the connection switching circuit so that the output voltage of the series circuit of the first battery and the second battery is applied to the high-voltage capacitor, the control circuit executes parallel charging start processing. The parallel charging start processing includes: A process of discharging the high-voltage capacitor via the converter circuit and the three-phase motor in a state where the connection switching circuit is controlled so that the voltage application from the series circuit to the high-voltage capacitor is stopped; A process of charging the high-voltage capacitor by controlling the connection switching circuit so that the output voltage of the first battery is applied to the high-voltage capacitor; and A process of controlling the connection switching circuit so that the first battery is connected between the high-potential wiring and the low-potential wiring, the second battery is connected between the neutral point and the low-potential wiring, and the charging voltage generated by the power supplied from the external charging device is applied between the high-potential wiring and the low-potential wiring, thereby performing parallel charging of the first battery and the second battery.

[0005] In addition, the above charging voltage may be the voltage supplied from an external charging device to the charging interface, or may be a voltage obtained by transforming the voltage supplied from the external charging device to the charging interface (for example, a DC voltage obtained by transforming an AC voltage).

[0006] In the parallel charging start process of the electronic circuit, after the discharge of the high-voltage capacitor and the charging of the high-voltage capacitor by the first battery, parallel charging of the first battery and the second battery is performed. Since charging and discharging of the low-voltage capacitor are not performed, parallel charging of the batteries can be started in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Hereinafter, features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which the same reference numerals denote the same components, where: Figure 1 is a circuit diagram of the electronic circuit of the embodiment; and Figure 2 is a flowchart of the parallel charging start process. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the above electronic circuit, the parallel charging start process may also be performed when the charging voltage is less than the output voltage of the series circuit.

[0009] In the above electronic circuit, the series operation may also be an operation of alternately performing the following processes: a process of transferring power from the first battery to the second battery via the converter circuit and the three-phase motor; and a process of transferring power from the second battery to the first battery via the converter circuit and the three-phase motor.

[0010] According to this configuration, the temperature of each battery can be increased during the series operation.

[0011] Figure 1 The shown electronic circuit 10 is mounted on a vehicle. The electronic 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 motor for use in 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. As a result, the three-phase motor 40 rotates the drive wheels and the vehicle travels. The output voltage V1 of the first battery 11 is substantially equal to the output voltage V2 of the second battery 12.

[0012] 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.

[0013] The converter circuit 30 is connected to the terminals 41U, 41V, and 41W of the three-phase motor 40. The converter 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 switch elements 35 connected in series between the high-potential wiring 31 and the low-potential wiring 32. Hereinafter, one of the two reverse-conducting switch elements 35 connected in series and connected to the high-potential wiring 31 may be referred to as an upper-side reverse-conducting switch element, and one connected to the low-potential wiring 32 may be referred to as a lower-side reverse-conducting switch element. Each reverse-conducting switch element 35 has a structure 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 anti-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. In addition, the anode of the diode is connected to the low-potential terminal (i.e., the emitter or the source) of the switch element.

[0014] The series switch circuit 34U is provided for the winding 44U. The series switch circuit 34U has an upper-side reverse-conducting switch element 35UU and a lower-side reverse-conducting switch element 35UL. The high-potential terminal of the upper-side reverse-conducting switch element 35UU is connected to the high-potential wiring 31. The low-potential terminal of the upper-side reverse-conducting switch element 35UU and the high-potential terminal of the lower-side reverse-conducting switch element 35UL are connected to the terminal 41U. The low-potential terminal of the lower-side reverse-conducting switch element 35UL is connected to the low-potential wiring 32.

[0015] The series switch circuit 34V is provided for the winding 44V. The series switch circuit 34V has an upper-side reverse-conducting switch element 35VU and a lower-side reverse-conducting switch element 35VL. The high-potential terminal of the upper-side reverse-conducting switch element 35VU is connected to the high-potential wiring 31. The low-potential terminal of the upper-side reverse-conducting switch element 35VU and the high-potential terminal of the lower-side reverse-conducting switch element 35VL are connected to the terminal 41V. The low-potential terminal of the lower-side reverse-conducting switch element 35VL is connected to the low-potential wiring 32.

[0016] The series switch circuit 34W is provided for the winding 44W. The series switch circuit 34W has an upper reverse-conducting switch element 35WU and a lower reverse-conducting switch element 35WL. The high-potential terminal of the upper reverse-conducting switch element 35WU is connected to the high-potential wiring 31. The low-potential terminal of the upper reverse-conducting switch element 35WU and the high-potential terminal of the lower reverse-conducting switch element 35WL are connected to the terminal 41W. The low-potential terminal of the lower reverse-conducting switch element 35WL is connected to the low-potential wiring 32.

[0017] A high-voltage capacitor 36 is connected between the high-potential wiring 31 and the low-potential wiring 32. In addition, a voltmeter 37 is connected between the high-potential wiring 31 and the low-potential wiring 32.

[0018] A neutral-point wiring 50 is connected to the neutral point 46 of the three-phase motor 40. The neutral-point wiring 50 is connected to the positive electrode of the second battery 12. A low-voltage capacitor 60 is connected between the neutral-point wiring 50 and the low-potential wiring 32. In addition, a voltmeter 61 is connected between the neutral-point wiring 50 and the low-potential wiring 32.

[0019] The electronic circuit 10 has a charging interface 70. The charging interface 70 can connect to the connector of a charging device outside the vehicle. An AC voltage from an external charging device is applied to the charging interface 70. The charging interface 70 is connected to a conversion circuit 73. When an AC voltage is applied to the charging interface 70, the conversion circuit 73 converts the AC voltage into a DC voltage and outputs it to the output wirings 71, 72. The conversion circuit 73 outputs the DC voltage with the output wiring 71 at a higher potential than the output wiring 72.

[0020] The electronic circuit 10 has a plurality of relay switches 81 to 89. By switching each relay switch, the mutual connections 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 charging interface 70 are changed. That is, a connection switching circuit is constituted by the relay switches 81 to 89.

[0021] The relay switch 81 is provided between the negative electrode of the first battery 11 and the positive electrode of the second battery 12. If the relay switch 81 is turned on, the first battery 11 and the second battery 12 are connected in series.

[0022] The relay switch 82 is provided between the negative electrode of the first battery 11 and the negative electrode of the second battery 12. If the relay switch 82 is turned on, the negative electrode of the first battery 11 and the negative electrode of the second battery 12 are connected.

[0023] An ammeter 20 and a relay switch 83 are serially provided between the positive electrode of the first battery 11 and the high-potential wiring 31. If the relay switch 83 is turned on, the positive electrode of the first battery 11 is connected to the high-potential wiring 31.

[0024] A relay switch 84, a galvanometer 52, and a relay switch 85 are provided on the neutral point wiring 50. The relay switch 84 and the galvanometer 52 are provided on the neutral point wiring 50 between the low-voltage capacitor 60 and the battery 12. The relay switch 85 is provided on the neutral point wiring 50 between the low-voltage capacitor 60 and the neutral point 46. If the relay switches 84 and 85 are turned on, the positive electrode of the second battery 12 is connected to the neutral point 46 via the neutral point wiring 50.

[0025] A relay switch 86 is provided between the negative electrode of the second battery 12 and the low-potential wiring 32. If the relay switch 86 is turned on, the negative electrode of the second battery 12 is connected to the low-potential wiring 32.

[0026] A series circuit of a relay switch 87 and a resistor 87r is connected in parallel with the relay switch 86. If the relay switch 87 is turned on, the negative electrode of the second battery 12 is connected to the low-potential wiring 32 via the resistor 87r.

[0027] A relay switch 88 is provided between the positive electrode of the first battery 11 and the output wiring 71. If the relay switch 88 is turned on, the output wiring 71 is connected to the positive electrode of the first battery 11.

[0028] A relay switch 89 is provided between the negative electrode of the second battery 12 and the output wiring 72. If the relay switch 89 is turned on, the output wiring 72 is connected to the negative electrode of the second battery 12.

[0029] The electronic circuit 10 has a control circuit 90. The control circuit 90 is composed of a CPU, a memory, etc. A program for controlling the electronic circuit 10 is stored in the memory (storage medium) of the control circuit 90. The control circuit 90 controls the switching elements of each reverse-conducting switching element 35 and the relay switches 81 to 89 according to the program.

[0030] In normal operation, the control circuit 90 turns on the relay switches 81, 83, 86 and turns off the relay switches 82, 84, 85, 87, 88, 89. 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 output voltage V3 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 output voltage V3 is the voltage obtained by adding the output voltage V1 of the first battery 11 and the output voltage V2 of the second battery 12. 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. 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.

[0031] The control circuit 90 can perform a battery temperature-rising operation when the vehicle stops. For example, in a low-temperature environment, the performance of the batteries 11, 12 can be improved by raising the temperature of the batteries 11, 12 through the battery temperature-rising operation. In the battery temperature-rising operation, the control circuit 90 causes the converter circuit 30 and the three-phase motor 40 to operate as a converter circuit. More specifically, in the battery temperature-rising operation, the control circuit 90 causes at least one of the U-phase, V-phase, and W-phase to operate as a converter circuit. Since the U-phase, V-phase, and W-phase operate in the same manner, the operation of the U-phase will be described below.

[0032] During the battery temperature rising operation, the control circuit 90 turns on the relay switches 81, 83, 84, 85, 86 and turns off the relay switches 82, 87, 88, 89. In addition, the control circuit 90 switches the reverse conduction switch elements 35UU and 35UL according to the situation. If the reverse conduction switch element 35UU is turned on, the current flows from the positive electrode of the first battery 11 through the high potential wiring 31, the reverse conduction switch element 35UU, the winding 44U, and the neutral point wiring 50 to the negative electrode of the first battery 11. Then, if the reverse conduction switch element 35UU is turned off, an induced voltage is generated in the winding 44U. As a result, the current flows from the negative electrode of the second battery 12 through the low potential wiring 32, the diode of the reverse conduction switch element 35UL, the winding 44U, and the neutral point wiring 50 to the positive electrode of the second battery 12. In this way, by switching the reverse conduction switch element 35UU, the first battery 11 is discharged and the second battery 12 is charged, and the electric power is transferred from the first battery 11 to the second battery 12. In addition, if the reverse conduction switch element 35UL is turned on, the current flows from the positive electrode of the second battery 12 through the neutral point wiring 50, the winding 44U, the reverse conduction switch element 35UL, and the low potential wiring 32 to the negative electrode of the second battery 12. Then, if the reverse conduction switch element 35UL is turned off, an induced voltage is generated in the winding 44U. As a result, the current flows from the negative electrode of the first battery 11 through the neutral point wiring 50, the winding 44U, the diode of the reverse conduction switch element 35UU, and the high potential wiring 31 to the positive electrode of the first battery 11. In this way, if the reverse conduction switch element 35UL is switched, the second battery 12 is discharged and the first battery 11 is charged, and the electric power is transferred from the second battery 12 to the first battery 11. During the battery temperature rising operation, the control circuit 90 alternately performs the power transfer from the first battery 11 to the second battery 12 and the power transfer from the second battery 12 to the first battery 11. Thus, the control circuit 90 raises the temperatures of the first battery 11 and the second battery 12.

[0033] During the battery temperature rising operation, it is possible to connect an external charging device to the charging interface 70 and start charging the batteries 11 and 12. In this case, the charging voltage Vc output between the output wirings 71 and 72 from the conversion circuit 73 is lower than the output voltage V3 of the series circuit of the batteries 11 and 12 and higher than the output voltages V1 and V2 of the batteries 11 and 12. Thus, the control circuit 90 performs an operation of charging the batteries 11 and 12 by applying the charging voltage Vc to the batteries 11 and 12 in parallel (hereinafter referred to as the parallel charging operation). When changing from the battery temperature rising operation to the parallel charging operation, the control circuit 90 executes the Figure 2 parallel charging start process shown.

[0034] At Figure 2 the start, the control circuit 90 executes the battery temperature rising operation. That is, atFigure 2 At the beginning, relay switches 81, 83, 84, 85, 86 are turned on, and relay switches 82, 87, 88, 89 are turned off. In this state, the output voltage V3 of the series circuit of batteries 11 and 12 is applied to the high-voltage capacitor 36, and the output voltage V2 of the second battery 12 is applied to the low-voltage capacitor 60.

[0035] In S2, an external charging device is connected to the charging interface 70. Then, the control circuit 90 turns off all the reverse-conducting switch elements 35, ending the battery heating operation. Then, if the user performs a charging start operation on the external charging device, the external charging device sends a charging start instruction to the control circuit 90. Thus, in S4, the control circuit 90 receives the charging start instruction. Then, the control circuit 90 sequentially executes the processes starting from S6.

[0036] In S6, the control circuit 90 turns off the relay switch 86. Thereby, the potential of the low-potential wiring 32 floats. Even when the relay switch 86 is turned off, charges are respectively held in the high-voltage capacitor 36 and the low-voltage capacitor 60. Therefore, after the relay switch 86 is turned off, the voltage between the two ends of the high-voltage capacitor 36 is approximately equal to the output voltage V3, and the voltage between the two ends of the low-voltage capacitor 60 is approximately equal to the output voltage V2.

[0037] Next, in S8, the control circuit 90 performs a high-voltage capacitor discharge process. Here, the control circuit 90 turns on the upper-side reverse-conducting switch element 35 of one phase and the lower-side reverse-conducting switch element 35 of another phase among the series switch circuits 34U to 34W. As an example, the case where the upper-side reverse-conducting switch element 35UU and the lower-side reverse-conducting switch element 35VL are turned on is described. In this case, current flows from the high-potential terminal of the high-voltage capacitor 36 through the upper-side reverse-conducting switch element 35UU, the winding 44U, the winding 44V, and the lower-side reverse-conducting switch element 35VL to the low-voltage side terminal of the high-voltage capacitor 36. Thereby, the high-voltage capacitor 36 is discharged. In addition, in the high-voltage capacitor discharge process, the control circuit 90 prevents the discharge current from becoming too high by repeatedly switching at least one of the reverse-conducting switch elements 35UU and 35VL. In S8, the control circuit 90 discharges the high-voltage capacitor 36 until the voltage between the two ends of the high-voltage capacitor 36 (i.e., the detected voltage of the voltmeter 37) becomes 0V. After the voltage between the two ends of the high-voltage capacitor 36 drops to 0V, the control circuit 90 turns off both the reverse-conducting switch elements 35UU and 35VL, ending the high-voltage capacitor discharge process. In addition, in S8, the low-voltage capacitor 60 is not discharged. Therefore, after S8 ends, the voltage between the two ends of the low-voltage capacitor 60 is maintained at a voltage approximately equal to the output voltage V2.

[0038] In addition, there is usually a situation where the relay switch cannot be disconnected due to the fixation of the contact points. When the relay switch 86 fails to disconnect due to fixation, in S8, the voltage across the high-voltage capacitor 36 does not decrease. Thus, S8 is responsible for checking the fixation of the relay switch 86 at the same time. When the relay switch 86 is fixed, the control circuit 90 aborts the process.

[0039] Next, in S10, the control circuit 90 disconnects the relay switch 81.

[0040] Next, in S12, the control circuit 90 closes the relay switch 87. In addition, the control circuit 90 monitors the voltage across the high-voltage capacitor 36 using the voltmeter 37. When the relay switch 81 fails to disconnect due to fixation, if the relay switch 87 is closed, the high-voltage capacitor 36 is charged due to the series circuit of the batteries 11 and 12, and the voltage across the high-voltage capacitor 36 rises. On the other hand, when the relay switch 81 is disconnected, even if the relay switch 87 is closed, the voltage across the high-voltage capacitor 36 does not rise. Thus, it is possible to check the fixation of the relay switch 81 through S12. When the relay switch 81 is fixed, the control circuit 90 aborts the process.

[0041] Next, in S14, the control circuit 90 disconnects the relay switch 87, ending the check for the fixation of the relay switch 81.

[0042] Next, in S16, the control circuit 90 closes the relay switch 82. Thus, the negative electrode of the first battery 11 is connected to the negative electrode of the second battery 12.

[0043] Next, in S18, the control circuit 90 closes the relay switch 87. Thus, the negative electrodes of the first battery 11 and the second battery 12 are connected to the low-potential wiring 32 via the resistor 87r. Then, the output voltage V1 of the first battery 11 is applied to the high-voltage capacitor 36. Thus, the high-voltage capacitor 36 is charged by the output voltage V1. At this time, the resistor 87r is used to suppress the case where the charging current becomes extremely high. The control circuit 90 charges the high-voltage capacitor 36 until the voltage across the high-voltage capacitor 36 becomes equal to the output voltage V1. In addition, if the relay switch 87 is closed, the output voltage V2 of the second battery 12 is applied to the low-voltage capacitor 60. However, since the voltage across the low-voltage capacitor 60 is approximately equal to the output voltage V2 before S18 is implemented, even if the relay switch 87 is closed, the voltage across the low-voltage capacitor 60 hardly changes.

[0044] After the voltage across the high-voltage capacitor 36 rises to the output voltage V1, the control circuit 90 turns on the relay switch 86 in S20. Thus, the negative electrodes of the first battery 11 and the second battery 12 are directly connected to the low-potential wiring 32. After the control circuit 90 turns on the relay switch 86, it turns off the relay switch 87 in the subsequent S22.

[0045] Next, the control circuit 90 starts the parallel charging operation in S24. That is, the control circuit 90 first instructs the external charging device to start parallel charging. Then, the external charging device applies an AC voltage to the charging interface 70. Then, the conversion circuit 73 converts the AC voltage into a DC charging voltage Vc and outputs it between the output wirings 71 and 72. In addition, the control circuit 90 turns on the relay switches 88 and 89. After such control, the following state is achieved: the first battery 11 is connected between the high-potential wiring 31 and the low-potential wiring 32, the second battery 12 is connected between the neutral point 46 and the low-potential wiring 32, and the charging voltage Vc is applied between the high-potential wiring 31 and the low-potential wiring 32.

[0046] The charging voltage Vc is applied to the first battery 11. As described above, the charging voltage Vc is higher than the output voltage V1 of the first battery 11. Thus, the first battery 11 is charged.

[0047] In addition, during the parallel charging operation, the control circuit 90 turns on at least one of the upper-side reverse-conducting switch elements 35UU, 35VU, and 35WU. Hereinafter, the case where the upper-side reverse-conducting switch element 35UU is turned on will be taken as an example for explanation. If the upper-side reverse-conducting switch element 35UU is turned on, the high-potential wiring 31 is connected to the positive electrode of the second battery 12 via the upper-side reverse-conducting switch element 35UU, the winding 44U, and the neutral-point wiring 50. Thus, the charging voltage Vc is applied to the second battery 12. As described above, the charging voltage Vc is higher than the output voltage V2 of the second battery 12. Thus, the second battery 12 is charged. In addition, the charging current for the second battery 12 can be reduced by repeatedly switching the upper-side reverse-conducting switch element 35UU.

[0048] In this way, during the parallel charging operation, the first battery 11 and the second battery 12 are charged in parallel. Thus, the charging states of the first battery 11 and the second battery 12 can be restored.

[0049] As described above, in Figure 2 the parallel charging start process, the high-voltage capacitor 36 can be discharged without charging and discharging the low-voltage capacitor 60, and then the first battery 11 is connected to the high-voltage capacitor 36. Thus, the preparation for the parallel charging operation for the batteries 11 and 12 can be completed in a short time. Therefore, it is possible to prevent the preparation time from becoming long and causing a timeout error in the external charging device.

[0050] In addition, in the above-described embodiments, the case of transitioning from the battery heating operation to the parallel charging operation has been described. However, the operation state before the start of the parallel charging process is not limited to the battery heating operation. That is, the operation state before the start of the parallel charging process may be any operation state as long as the batteries 11 and 12 are connected in series, the high-voltage capacitor 36 is applied with the output voltage V3, and the low-voltage capacitor 60 is applied with the output voltage V2.

[0051] As described above, the embodiments have been described in detail, but these are merely examples and do not limit the claims. The technology described in the claims includes parts obtained by various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings are technical elements that exhibit technical usefulness either individually or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the technology illustrated in this specification or the drawings is a technology that achieves multiple purposes simultaneously, but it also has technical usefulness for achieving only one of the purposes itself.

Claims

1. An electronic circuit mounted on a vehicle, The electronic circuit has: A first battery; A second battery; A high-voltage capacitor; A low-voltage capacitor; A three-phase motor having 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. At the neutral point, the second connection terminals of the three windings are connected to each other; 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 charging interface connected to an external charging device; A connection switching circuit that changes the mutual connection of the first battery, the second battery, the converter circuit, the neutral point, and the charging interface; And A control circuit, The converter circuit has: A high-potential wiring; A low-potential wiring; and Three series switch circuits respectively provided for the three windings, Each of the series switch circuits has: an upper reverse-conducting switch element, which is a reverse-conducting switch element connecting the first connection terminal of the corresponding winding and the high-potential wiring; And a lower reverse-conducting switch element, which is a reverse-conducting switch element connecting the first connection terminal of the corresponding winding and the low-potential wiring, The high-voltage capacitor is connected between the high-potential wiring and the low-potential wiring, The low-voltage capacitor is connected between the neutral point and the low-potential wiring, When an external charging device is connected to the charging interface during the execution of the series operation in which the connection switching circuit is controlled so that the output voltage of the series circuit of the first battery and the second battery is applied to the high-voltage capacitor, the control circuit executes parallel charging start processing, The parallel charging start processing has: A process of discharging the high-voltage capacitor via the converter circuit and the three-phase motor in a state where the connection switching circuit is controlled so that the voltage application from the series circuit to the high-voltage capacitor is stopped; A process of charging the high-voltage capacitor by controlling the connection switching circuit so that the output voltage of the first battery is applied to the high-voltage capacitor; And Controlling the connection switching circuit so that the first battery is connected between the high-potential wiring and the low-potential wiring, the second battery is connected between the neutral point and the low-potential wiring, and the charging voltage generated by the power supplied from the external charging device is applied between the high-potential wiring and the low-potential wiring, thereby performing parallel charging of the first battery and the second battery.

2. The electronic circuit according to claim 1, wherein When the charging voltage is less than the output voltage of the series circuit, the control circuit executes the parallel charging start processing.

3. The electronic circuit according to claim 1 or 2, wherein The series operation is an operation that alternately performs the following processes: a process of transferring power from the first battery to the second battery via the converter circuit and the three-phase motor; and a process of transferring power from the second battery to the first battery via the converter circuit and the three-phase motor.

4. A program product that causes an electronic circuit mounted on a vehicle to perform a charging process, The electronic circuit includes: A first battery; A second battery; A high-voltage capacitor; A low-voltage capacitor; A three-phase motor having 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. At the neutral point, the second connection terminals of the three windings are connected to each other; 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 charging interface connected to an external charging device; A connection switching circuit that changes the mutual connection of the first battery, the second battery, the converter circuit, the neutral point, and the charging interface; And A control circuit, The converter circuit includes: A high-potential wiring; A low-potential wiring; and Three series switching circuits respectively provided for the three windings, Each of the series switching circuits includes: an upper reverse-conducting switch element, which is a reverse-conducting switch element that connects between the first connection terminal of the corresponding winding and the high-potential wiring; And a lower reverse-conducting switch element, which is a reverse-conducting switch element that connects between the first connection terminal of the corresponding winding and the low-potential wiring, The high-voltage capacitor is connected between the high-potential wiring and the low-potential wiring, The low-voltage capacitor is connected between the neutral point and the low-potential wiring, When an external charging device is connected to the charging interface during the execution of the series operation in which the connection switching circuit is being controlled so that the output voltage of the series circuit of the first battery and the second battery is applied to the high-voltage capacitor, the program causes the control circuit to perform a parallel charging start process, The parallel charging start process includes: A process of discharging the high-voltage capacitor via the converter circuit and the three-phase motor in a state where the connection switching circuit is controlled so that the voltage application from the series circuit to the high-voltage capacitor is stopped; A process of charging the high-voltage capacitor by controlling the connection switching circuit so that the output voltage of the first battery is applied to the high-voltage capacitor; And Controlling the connection switching circuit so that the first battery is connected between the high-potential wiring and the low-potential wiring, the second battery is connected between the neutral point and the low-potential wiring, and the charging voltage generated by the power supplied from the external charging device is applied between the high-potential wiring and the low-potential wiring, thereby performing a parallel charging process for the first battery and the second battery.

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