Electrical circuit and program for charging processing

Abstract

The invention provides an electrical circuit and a program for charging processing. An electrical circuit mounted on a vehicle includes a first battery, a second battery, a three-phase motor, an inverter circuit, a charging socket, a connection switching circuit, and a control circuit. The control circuit selectively executes a step-down charging operation and a direct charging operation in a case where no aging is determined in the aging determination process so that the step-down charging operation is executed in a case where the output voltage difference is larger than a reference value and the direct charging operation is executed in a case where the output voltage difference is smaller than the reference value. When it is determined that there is aging in the aging determination process, the control circuit executes the step-down charging operation regardless of the output voltage difference.

Description

Technical Field

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

[0002] Japanese Patent Application No. 2020-120566 discloses an electrical circuit mounted on a vehicle. The electrical 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 the DC power supplied from the series circuit of the batteries into AC power and supplying it to the three-phase motor. In addition, the electrical circuit has wiring connecting 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 the wiring, each battery can be heated up. Summary of the invention

[0003] In an electrical circuit having two batteries, a converter circuit, and a three-phase motor, there is a technology for connecting a charging device outside the vehicle to the electrical circuit and charging each battery. One battery is connected to the charging device via wiring. The other battery is connected to the charging device via a converter circuit and a three-phase motor. According to this structure, two batteries can be charged in parallel. In the charging process of this electrical circuit, when a high current flows to an aged battery, the aging of the battery worsens. In this specification, a technology that can suppress the aging of the battery and charge the battery efficiently is proposed.

[0004] The electric circuit disclosed in this specification is mounted on a vehicle. The electric circuit has a first battery, a second battery, a three-phase motor, a converter circuit, a charging socket, 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. The three windings respectively have 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 a 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 socket has a high potential charging terminal and a low potential charging terminal, and is connected to a charging device outside the vehicle. The connection switching circuit changes the mutual connection relationship between the first battery, the second battery, the converter circuit, the neutral point and the charging socket. 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. The series switch circuits each include a reverse conducting switch element connected between the first connection terminal of the corresponding winding and the high potential wiring, that is, an upper reverse conducting switch element, and a reverse conducting switch element connected between the first connection terminal of the corresponding winding and the low potential wiring, that is, a lower reverse conducting switch element. The control circuit can control the connection switching circuit to the following charging mode: the positive electrode of the first storage battery and the high potential wiring are connected to the high potential charging terminal through the connection switching circuit, the negative electrode of the first storage battery, the negative electrode of the second storage battery, and the low potential wiring are connected to the low potential charging terminal through the connection switching circuit, and the positive electrode of the second storage battery is connected to the neutral point through the connection switching circuit. When the first storage battery and the second storage battery are charged through the charging socket, the control circuit performs an aging determination process, a first charging process, and a second charging process. In the aging determination process, the control circuit determines the aging of at least one of the first storage battery and the second storage battery. In the first charging process, when the control circuit determines that there is no aging in the aging determination process, the control circuit selectively performs a step-down charging operation and a direct charging operation, so that the step-down charging operation is performed when the output voltage difference obtained by subtracting the output voltage of the second storage battery from the output voltage of the first storage battery is larger than a reference value, and the direct charging operation is performed when the output voltage difference is smaller than the reference value. In the second charging process, when the control circuit determines that there is aging in the aging determination process, the control circuit performs the step-down charging operation regardless of the output voltage difference.The step-down charging operation is an operation in which the three lower reverse conducting switching elements are controlled to be turned off in the charging mode and at least one of the three upper reverse conducting switching elements is repeatedly turned on. The direct charging operation is an operation in which the three lower reverse conducting switching elements are controlled to be turned off and at least one of the three upper reverse conducting switching elements is maintained to be turned on in the charging mode.

[0005] It should be noted that, in this specification, the reverse conducting switch element refers to an element that connects the switch element and the diode in parallel. In detail, the reverse conducting switch element refers to an element that connects the cathode of the diode to the high potential side terminal of the switch element and connects the anode of the diode to the low potential side terminal of the switch element. It should be noted that the switch element may also be a semiconductor switch element such as a field effect transistor and an insulated gate bipolar transistor. The diode may be either a pn diode or a Schottky barrier diode. Furthermore, the switch element and the diode may be provided on a common semiconductor substrate or on different semiconductor substrates. Furthermore, in this specification, the connection of the reverse conducting switch element refers to the connection of the switch element possessed by the reverse conducting switch element, and the disconnection of the reverse conducting switch element refers to the disconnection of the switch element possessed by the reverse conducting switch element.

[0006] Furthermore, in the deterioration determination process, the deterioration of one of the first storage battery and the second storage battery may be determined, or the deterioration of both the first storage battery and the second storage battery may be determined.

[0007] In this electrical circuit, the control circuit performs a first charging process when it is determined that there is no aging of the battery. In the first charging process, the control circuit selectively performs a step-down charging action and a direct charging action according to the output voltage difference. In the step-down charging action, the generation of excessive current can be suppressed, and on the other hand, the charging current relative to the second battery becomes lower. In the direct charging action, when the output voltage difference is high, an excessive current may be generated, and on the other hand, the second battery can be charged with a higher charging current. In the first charging process, the step-down charging action and the direct charging action are selectively performed according to the output voltage difference, so that the excessive current can be suppressed and the first battery and the second battery can be charged efficiently. In addition, the control circuit performs a second charging process when it is determined that there is aging of the battery. In the second charging process, the step-down charging action is performed regardless of the output voltage difference. Therefore, the current flowing to the first battery and the second battery can be further reduced, and the aging of the first battery and the second battery can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Features, advantages, technical and industrial significance of embodiments of the present invention are described below with reference to the accompanying drawings, wherein like reference numerals denote like elements.

[0009] Figure 1 3 is a circuit diagram of an electric circuit according to the embodiment (a circuit diagram showing a current path when the upper reverse conducting switching element 35VU is turned on).

[0010] Figure 2 It is a flow chart of charging control.

[0011] Figure 3 This is a flowchart of the first charging process.

[0012] Figure 4 It is a circuit diagram of an electric circuit according to the embodiment (a circuit diagram showing a current path when the upper reverse conducting switching element 35VU is off during the step-down charging operation).

[0013] Figure 5 This is a flowchart of the second charging process. DETAILED DESCRIPTION

[0014] In an electrical circuit of an example disclosed in the present specification, the control circuit may also perform a unilateral charging operation of charging the first battery without charging the second battery when the output voltage of the first battery is lower than the output voltage of the second battery before the first charging process and the second charging process start.

[0015] In the electric circuit of the example disclosed in the present specification, the control circuit may determine that the first storage battery has deteriorated in the deterioration determination process when an output voltage of the first storage battery is lower than an output voltage of the second storage battery.

[0016] Figure 1 The electric circuit 10 shown is mounted on a vehicle. The electric 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 driving the vehicle. The converter circuit 30 converts the DC power supplied from the first battery 11 and the second battery 12 into AC power and supplies it to the three-phase motor 40. As a result, the three-phase motor 40 rotates the drive wheels, 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. Terminals 42U, 42V, and 42W are connected to each other at a neutral point 46.

[0018] 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. The series switch circuits 34U, 34V, and 34W are respectively 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 of the two reverse conducting switch elements 35 connected in series is sometimes referred to as the upper side reverse conducting switch element, and the reverse conducting switch element connected to the low potential wiring 32 is sometimes referred to as the lower side reverse conducting switch element. Each reverse conducting switch element 35 has a structure in which a switch element (such as an insulated gate bipolar transistor or a field effect transistor) and a diode (such as 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 (ie, collector or drain) of the switch element, and the anode of the diode is connected to the low potential terminal (ie, emitter or source) of the switch element.

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

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

[0021] The series switch circuit 34W is provided relative to the winding 44W. The series switch circuit 34W includes 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.

[0022] A capacitor 36 is connected between the high potential wiring 31 and the low potential wiring 32 . Furthermore, 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. Furthermore, a voltmeter 61 is connected between the neutral point wiring 50 and the low potential wiring 32.

[0024] The electrical circuit 10 has a charging socket 70. A connector of a charging device outside the vehicle can be connected to the charging socket 70. The charging socket 70 has a high potential charging terminal 71 and a low potential charging terminal 72. When the connector of the charging device is connected to the charging socket 70, a DC voltage is applied between the high potential charging terminal 71 and the low potential charging terminal 72 by the charging device in a direction in which the high potential charging terminal 71 is at a high potential.

[0025] The electric circuit 10 includes a plurality of relay switches 81 to 88. Each relay switch switches on and off to change the connection relationship among the first battery 11, the second battery 12, the high potential line 31, the low potential line 32, the neutral point 46, and the charging inlet 70.

[0026] The relay switch 81 is provided 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.

[0027] The relay switch 82 is provided 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 and the negative electrode of the second storage battery 12 are connected.

[0028] The ammeter 20 and the relay switch 83 are provided 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 and the high potential wiring 31 are connected.

[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 and the low potential wiring 32 are connected.

[0030] The relay switch 85 is provided between the low potential charging terminal 72 and the low potential wiring 32. When the relay switch 85 is turned on, the low potential charging terminal 72 and the low potential wiring 32 are connected.

[0031] The relay switch 86 is provided between the high potential charging terminal 71 and the high potential wiring 31. When the relay switch 86 is turned on, the high potential charging terminal 71 and the high potential wiring 31 are connected.

[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. 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 and the neutral point 46 are connected.

[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 switch elements of each reverse conducting switch element 35 and the relay switches 81 to 88 according to the program. The control circuit 90 can perform normal control and charging control.

[0034] In normal control, 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 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 rotation 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] In the charging control, the control circuit 90 executes the charging control program to charge the first storage battery 11 and the second storage battery 12. When an external charging device is connected to the charging inlet 70, the control circuit 90 starts the charging control.

[0036] like Figure 2As shown, after the control circuit 90 starts the charging control, it determines the aging of the batteries 11 and 12 in S12. The aging of the batteries 11 and 12 can be determined by various methods known in the art. For example, the aging of the batteries 11 and 12 can be determined based on the history of the SOC (State Of Charge) or OCV (Open Circuit Voltage) of the batteries 11 and 12 to date. In addition, when the first battery 11 ages, the OCV of the first battery 11 may become lower than the OCV of the second battery 12. In this case, when the relay switches 82, 83, 87, and 88 are turned on in a state where all the reverse conducting switch elements 35 are turned off, a current (hereinafter referred to as a leakage current) flows from the positive electrode of the second storage battery 12 to the positive electrode of the first storage battery 11 via the neutral point wiring 50, the windings 44U to 44W, the diodes of the upper reverse conducting switch elements 35UU, 35VU, and 35WU, and the high potential wiring 31. When the first storage battery 11 is not deteriorated (that is, when the OCV of the first storage battery 11 is higher than the OCV of the second storage battery 12), the leakage current does not flow. Therefore, the deterioration of the first storage battery 11 can also be determined by detecting whether the leakage current flows using the ammeter 20 or 52.

[0037] The control circuit 90 performs the first charging process in S14 when no deterioration occurs in either the first battery 11 or the second battery 12. Also, the control circuit 90 performs the second charging process in S16 when at least one of the first battery 11 and the second battery 12 has deteriorated.

[0038] Figure 3The first charging process is shown. In the first charging process, the control circuit 90 first determines in S20 whether the OCV of the first storage battery 11 (hereinafter referred to as OCV1) is greater than the OCV of the second storage battery 12 (hereinafter referred to as OCV2). The relay switches 82, 83, and 84 can be turned on when the relay switches 85 and 86 are turned off, so that the OCV1 of the first storage battery 11 can be measured by the voltmeter 37. In addition, the relay switches 84 and 87 can be turned on when the relay switches 85 and 86 are turned off, so that the OCV2 of the second storage battery 12 can be measured by the voltmeter 61. In addition, it is also possible to determine whether OCV1 is greater than OCV2 by detecting the above-mentioned leakage current. In addition, when the charging current is supplied by an external charging device, it is difficult to directly measure OCV1 and OCV2. In this case, instead of directly measuring OCV1 and OCV2, OCV1 and OCV2 can be predicted by calculation. Furthermore, the charging current supplied from the external charging equipment may be reduced, and the CCV (Closed Circuit Voltage) of the storage batteries 11 and 12 may be measured in a low current state, and the measured CCV may be virtually regarded as OCV1 and OCV2.

[0039] When OCV1 is smaller than OCV2, the control circuit 90 performs a unilateral charging operation in S22. The unilateral charging operation is an operation of charging the first battery 11 without charging the second battery 12. In the unilateral charging operation, the control circuit 90 turns on the relay switches 82 to 86 and turns off the relay switches 81, 87, and 88. As a result, the positive electrode of the first battery 11 is connected to the high potential charging terminal 71 via the relay switches 83 and 86, and the negative electrode of the first battery 11 is connected to the low potential charging terminal 72 via the relay switches 82, 84, and 85. Therefore, the output voltage of the external charging device is applied to the first battery 11, and the first battery 11 is charged. The positive electrode of the second battery 12 is floated due to the disconnection of the relay switches 81 and 87, so the second battery 12 is not charged. Therefore, the first battery 11 is charged without charging the second battery 12.

[0040] The control circuit 90 charges the first storage battery 11 by repeating S20 and S22 until OCV1 becomes higher than OCV2. When OCV1 becomes higher than OCV2, the control circuit 90 determines YES in S20 and executes S24.

[0041] In S24, the control circuit 90 charges the storage batteries 11 and 12 using the operation method corresponding to OCV1 and OCV2. Since OCV1 and OCV2 change during the charging of the storage batteries 11 and 12, the control circuit 90 changes the operation method during the charging. S24 will be described in detail below.

[0042] In S24, the control circuit 90 periodically detects OCV1 and OCV2. OCV1 and OCV2 can be detected by any of the methods described in S20. In addition, the control circuit 90 calculates the voltage difference ΔV (ΔV=OCV1-OCV2) obtained by subtracting OCV2 from OCV1. The control circuit 90 performs a step-down charging operation when the voltage difference ΔV is higher than the reference value ΔVth. The control circuit 90 performs a direct charging operation when the voltage difference ΔV is lower than the reference value ΔVth and higher than 0V. The control circuit 90 performs a single-side charging operation when the voltage difference ΔV is lower than 0V. The step-down charging operation is an operation of charging the first storage battery 11 and the second storage battery 12 in parallel, and is an operation of charging the second storage battery 12 with a relatively low voltage. The direct charging operation is an operation of charging the first storage battery 11 and the second storage battery 12 in parallel, and is an operation of charging the second storage battery 12 with a higher voltage than the step-down charging operation. The one-side charging operation is an operation of charging the first storage battery 11 without charging the second storage battery 12 .

[0043] In the step-down charging operation, the control circuit 90 turns on the relay switches 82 to 88 and turns off the relay switch 81. Hereinafter, this control state is sometimes referred to as a charging mode. In the charging mode, the positive electrode of the first storage battery 11 and the high potential wiring 31 are connected to the high potential charging terminal 71. Also, in the charging mode, the negative electrode of the first storage battery 11, the negative electrode of the second storage battery 12, and the low potential wiring 32 are connected to the low potential charging terminal 72. Also, in the charging mode, the positive electrode of the second storage battery 12 is connected to the neutral point 46. Also, in the step-down charging operation, the control circuit 90 turns off the lower side reverse conducting switch elements 35UL, 35VL, 35WL. Also, in the step-down charging operation, the control circuit 90 repeatedly switches at least one of the upper side reverse conducting switch elements 35UU, 35VU, 35WU (hereinafter referred to as a specific switch element). When there is an element other than the specific switching element among the upper reverse conducting switching elements 35UU, 35VU, and 35WU, the control circuit 90 keeps the elements other than the specific switching element OFF. The current path when the upper reverse conducting switching element 35VU is the specific switching element will be described below.

[0044] As described above, in the step-down charging operation, the positive electrode of the first battery 11 is connected to the high potential charging terminal 71, and the negative electrode of the first battery 11 is connected to the low potential charging terminal 72. Therefore, the output voltage of the external charging device is applied to the first battery 11, and the first battery 11 is charged. And, as described above, in the step-down charging operation, the high potential wiring 31 is connected to the high potential charging terminal 71, the low potential wiring 32 is connected to the low potential charging terminal 72, the positive electrode of the second battery 12 is connected to the neutral point 46, and the negative electrode of the second battery 12 is connected to the low potential charging terminal 72. In this state, when the upper side reverse conducting switch element 35VU (i.e., the specific switch element) is turned on, as shown in FIG. Figure 1 As shown by the arrow 100, the current flows from the high potential charging terminal 71 to the low potential charging terminal 72 via the high potential wiring 31, the upper reverse conducting switch element 35VU, the winding 44V, the neutral point wiring 50 and the second storage battery 12. Then, when the upper reverse conducting switch element 35VU is turned off, an induced electromotive force is generated in the winding 44V. As a result, Figure 4 As shown by the arrow 102, the return current flows through the diode of the lower reverse conducting switch element 35VL, the winding 44V and the second battery 12. In the step-down operation, the second battery 12 is charged by the current flowing alternately along the paths shown by the arrows 100 and 102. In this way, in the step-down operation, the converter circuit 30 and the winding of the three-phase motor 40 function as a step-down converter circuit. Therefore, a voltage lower than the output voltage of the external charging device is applied to the second battery 12, and the second battery 12 is charged with a lower charging current.

[0045] In the direct charging operation, the control circuit 90 controls the relay switches 81 to 88 to the charging mode. In addition, in the direct charging operation, the control circuit 90 turns off the lower reverse conducting switch elements 35UL, 35VL, and 35WL. In addition, in the direct charging operation, the control circuit 90 maintains the specific switch element of the upper reverse conducting switch elements 35UU, 35VU, and 35WU to be turned on. In the case where there are elements other than the specific switch element in the upper reverse conducting switch elements 35UU, 35VU, and 35WU, the control circuit 90 maintains the elements other than the specific switch element to be turned off. The current path when the upper reverse conducting switch element 35VU is the specific switch element is described below.

[0046] In the direct charging operation, the output voltage of the external charging device is applied to the first storage battery 11, similarly to the step-down charging operation, to charge the first storage battery 11. In the direct charging operation, the upper reverse conducting switch element 35VU is always turned on, so the DC current is Figure 1The current flows along the path indicated by the arrow 100 to charge the second storage battery 12. In the direct charging operation, the specific switching element is always turned on, so the output voltage of the external charging device is applied to the second storage battery 12 without stepping down. Therefore, in the direct charging operation, the second storage battery 12 is charged with a higher charging current than in the step-down charging operation.

[0047] When the direct charging operation is performed in a state where the voltage difference ΔV is large (i.e., the output voltage of the first storage battery 11 is much higher than the output voltage of the second storage battery 12), the output voltage of the first storage battery 11 is applied to the second storage battery 12, and an excessive current flows from the first storage battery 11 to the second storage battery 12. As a result, a high load is applied to the storage batteries 11 and 12. In contrast, in the first charging process, the step-down charging operation is performed in a state where the voltage difference ΔV is large, and the excessive current is suppressed from flowing from the first storage battery 11 to the second storage battery 12. Thus, the load applied to the storage batteries 11 and 12 is reduced. Furthermore, in the first charging process, in a state where the voltage difference ΔV is not large, it is impossible for an excessive current to flow, so the direct charging operation is performed. Thus, the second storage battery 12 is charged efficiently.

[0048] Furthermore, when ΔV<0 (i.e., OCV1<OCV2) in S24, the control circuit 90 performs a single-side charging operation. The single-side charging operation performed in S24 is the same as the single-side charging operation performed in S22. When OCV2 rises to ΔV<0 by the direct charging operation, OCV1 and OCV2 are adjusted to ΔV>0 by the single-side charging operation.

[0049] As described above, in the first charging process, the step-down charging operation, the direct charging operation, and the one-side charging operation are selectively performed according to ΔV. This can suppress the generation of excessive current and efficiently charge the second storage battery 12 .

[0050] Next, the second charging process will be described. As described above, when at least one of the first storage battery 11 and the second storage battery 12 has deteriorated, the control circuit 90 executes the second charging process in S16. Figure 5The second charging process is shown. S30 and S32 of the second charging process are the same as S20 and S22 of the first charging process. That is, in S30 and S32, OCV1 and OCV2 are adjusted in such a manner that OCV1>OCV2. Then, the control circuit 90 performs a step-down charging action in S34 to charge the batteries 11 and 12. The step-down charging action performed in S34 is the same as the step-down charging action performed in S24. In S34, the control circuit 90 performs the step-down charging action regardless of the voltage difference ΔV. In this way, when aging occurs in at least one of the first battery 11 and the second battery 12, the direct charging action is prohibited and the step-down charging action is performed. As a result, a higher current is suppressed from flowing from the first battery 11 to the second battery 12, and further aging of the batteries 11 and 12 is suppressed.

[0051] As described above, in the electric circuit 10 of the present embodiment, when the storage batteries 11 and 12 have not deteriorated, the direct charging operation is permitted in S24, and the second storage battery 12 is efficiently charged. Furthermore, when the storage batteries 11 and 12 have deteriorated, the direct charging operation is prohibited in S34, and further deterioration of the storage batteries 11 and 12 is suppressed.

[0052] The above detailed description of the implementation methods is provided, but these are only examples and do not limit the claims. The technology described in the claims includes various technical solutions after various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exert technical practicality alone or in various combinations, and are not limited to the combinations recorded in the claims at the time of application. In addition, the technology illustrated in this specification or drawings can achieve multiple purposes at the same time, and achieving one of the purposes itself also has technical practicality.

Claims

1. An electrical circuit mounted on a vehicle, the electrical circuit comprising: First battery; Second battery; A three-phase motor having 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 charging socket, having a high potential charging terminal and a low potential charging terminal, connected to a charging device outside the vehicle; A connection switching circuit is used to change the mutual connection relationship among the first storage battery, the second storage battery, the converter circuit, the neutral point and the charging socket; 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 control circuit is capable of controlling the connection switching circuit to the following charging mode: the positive electrode of the first storage battery and the high potential wiring are connected to the high potential charging terminal through the connection switching circuit, the negative electrode of the first storage battery, the negative electrode of the second storage battery, and the low potential wiring are connected to the low potential charging terminal through the connection switching circuit, and the positive electrode of the second storage battery is connected to the neutral point through the connection switching circuit. When the first storage battery and the second storage battery are charged through the charging socket, the control circuit performs an aging determination process, a first charging process, and a second charging process. In the deterioration determination process, deterioration of at least one of the first storage battery and the second storage battery is determined. In the first charging process, when it is determined in the aging determination process that there is no aging, a step-down charging action and a direct charging action are selectively performed, so that the step-down charging action is performed when an output voltage difference obtained by subtracting an output voltage of the second storage battery from an output voltage of the first storage battery is larger than a reference value, and the direct charging action is performed when the output voltage difference is smaller than the reference value, In the second charging process, when it is determined in the deterioration determination process that deterioration exists, the step-down charging operation is performed regardless of the output voltage difference. The step-down charging operation is an operation in which the three lower reverse conducting switching elements are controlled to be off in the charging mode and at least one of the three upper reverse conducting switching elements is repeatedly switched. The direct charging operation is an operation of controlling the three lower reverse conducting switching elements to be turned off and maintaining at least one of the three upper reverse conducting switching elements to be turned on in the charging mode.

2. The electrical circuit according to claim 1, wherein: The control circuit performs a one-side charging operation of charging the first battery without charging the second battery when the output voltage of the first battery is lower than the output voltage of the second battery before the first and second charging processes are started.

3. The electrical circuit according to claim 1 or 2, wherein: The control circuit determines that the first storage battery has deteriorated when the output voltage of the first storage battery is lower than the output voltage of the second storage battery in the deterioration determination process.

4. A program for charging processing, causing an electrical circuit mounted on a vehicle to execute charging processing, wherein: The electrical circuit has: First battery; Second battery; A three-phase motor having 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 charging socket, having a high potential charging terminal and a low potential charging terminal, connected to a charging device outside the vehicle; A connection switching circuit is used to change the mutual connection relationship among the first storage battery, the second storage battery, the converter circuit, the neutral point and the charging socket; 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 enables the control circuit to execute a charging mode, The charging mode is a mode in which the positive electrode of the first storage battery and the high potential wiring are connected to the high potential charging terminal through the connection switching circuit, the negative electrode of the first storage battery, the negative electrode of the second storage battery, and the low potential wiring are connected to the low potential charging terminal through the connection switching circuit, and the positive electrode of the second storage battery is connected to the neutral point through the connection switching circuit. When the first storage battery and the second storage battery are charged through the charging socket, the program causes the control circuit to execute a degradation determination process, a first charging process, and a second charging process. In the deterioration determination process, deterioration of at least one of the first storage battery and the second storage battery is determined. In the first charging process, when it is determined in the aging determination process that there is no aging, a step-down charging action and a direct charging action are selectively performed, so that the step-down charging action is performed when an output voltage difference obtained by subtracting an output voltage of the second storage battery from an output voltage of the first storage battery is larger than a reference value, and the direct charging action is performed when the output voltage difference is smaller than the reference value, In the second charging process, when it is determined in the deterioration determination process that deterioration exists, the step-down charging operation is performed regardless of the output voltage difference. The step-down charging operation is an operation in which the three lower reverse conducting switching elements are controlled to be off in the charging mode and at least one of the three upper reverse conducting switching elements is repeatedly switched. The direct charging operation is an operation of controlling the three lower reverse conducting switching elements to be turned off and maintaining at least one of the three upper reverse conducting switching elements to be turned on in the charging mode.

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