Relay circuit and vehicle provided therewith

Abstract

To effectively reduce power consumption during electrical contact drive time.SOLUTION: A relay circuit 110 comprises a contact relay 120-B and a voltage generation circuit 122. The contact relay 120-B includes an electrical contact RY11 and a coil DCR-B1. The coil DCR-B1 drives the electrical contact RY11. The voltage generation circuit 122 generates an applied voltage V11 to the coil DCR-B1. The electrical contact RY11 is closed when an applied voltage V11 exceeds the working voltage of the contact relay 120-B and opened when the applied voltage V11 decreases below the return voltage of the contact relay 120-B which is lower than the working voltage. The voltage generation circuit 122 generates the applied voltage V11 so that the applied voltage V11 exceeds the working voltage so as to close the electrical contact RY11 and thereafter generates the applied voltage V11 so that the applied voltage V11 decreases to and is held at a step-down voltage VCC which is below the working voltage and higher than the return voltage.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a relay circuit and a vehicle including the same. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2007-244034 (Patent Document 1) discloses a power supply device for a vehicle. This power supply device includes a battery and a contact relay. The electrical contacts of the contact relay are driven using the power of the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-244034 A Summary of the Invention [Problem to be solved by the invention]

[0004] The electrical contacts are generally driven by a coil. For example, the electrical contacts are opened or closed according to a voltage applied to the coil. Patent Document 1 does not discuss a technique for effectively reducing power consumption when driving the electrical contacts.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a relay circuit and a vehicle that can effectively reduce power consumption when driving an electrical contact. [Means for solving the problem]

[0006] The relay circuit of the present disclosure includes a contact relay and a voltage generation circuit. The contact relay includes an electric contact and a coil that drives the electric contact. The voltage generation circuit is connected to the coil and generates an applied voltage to the coil. The electric contact is closed when the applied voltage exceeds a first voltage, and is opened when the applied voltage falls below a second voltage that is lower than the first voltage. The voltage generation circuit generates an applied voltage such that the applied voltage exceeds the first voltage to close the electric contact, and then generates an applied voltage such that the applied voltage drops to and is maintained at a third voltage that is lower than the first voltage and higher than the second voltage. Effect of the Invention

[0007] According to the present disclosure, it is possible to effectively reduce power consumption when driving electrical contacts. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle on which a relay circuit is mounted; [Diagram 2] FIG. 2 is a diagram illustrating a detailed configuration of a relay circuit. [Diagram 3] FIG. 4 is a timing chart for specifically explaining the transition of the voltage applied to the coil. [Figure 4] 4 is a flowchart illustrating a process executed by a control unit. [Diagram 5] FIG. 2 is a diagram illustrating a detailed configuration of a relay circuit. [Figure 6] FIG. 4 is a timing chart for specifically explaining the transition of the voltage applied to the coil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated. Each of the embodiments and their modified examples may be appropriately combined with each other.

[0010] Fig. 1 is a diagram that illustrates a schematic configuration of a vehicle equipped with a relay circuit according to an embodiment. With reference to Fig. 1, vehicle 10 is a battery electric vehicle (BEV). Vehicle 10 is configured to be capable of transmitting power between vehicle 10 and power equipment 20 (described later) that is provided outside vehicle 10. Vehicle 10 may be replaced by another type of electric vehicle, such as a plug-in hybrid electric vehicle (PHEV).

[0011] The vehicle 10 includes a battery 102, power lines PL1-PL3 and NL1-NL3, an inlet 104, a drive device 105, relay circuits 110 and 115, voltage sensors 150 and 160, a capacitor 155, and an ECU (Electronic Control Unit) 180.

[0012] The battery 102 is a secondary battery such as a lithium ion battery, and is an example of the “power storage device” of the present disclosure. The battery 102 stores electric power for running the vehicle 10.

[0013] The power line PL1 is a high-potential side power line connected to the positive terminal of the battery 102. The power line NL1 is a low-potential side power line connected to the negative terminal of the battery 102.

[0014] The inlet 104 is configured to be connectable to power equipment 20. The power equipment 20 includes a power feeding device 205 and a connector 210. The power feeding device 205 feeds power to the vehicle 10 using power from the power grid PG. The connector 210 is connected (inserted) to the inlet 104.

[0015] The drive device 105 includes an inverter 106 and a motor 108. The inverter 106 is connected to power lines PL2, NL2, and converts DC power supplied from the battery 102 through a relay circuit 115 (described later) into AC power. The motor 108 receives this AC power and generates driving force for running the vehicle 10. The power lines PL2, NL2 are a high-potential side power line and a low-potential side power line connected to the drive device 105, respectively.

[0016] The relay circuit 110 is connected to a pair of power lines (power lines PL3, NL3) connected to the inlet 104. The relay circuit 110 includes terminals P1, P2, N1, and N2. The terminals P1 and N1 are connected to the power lines PL3 and NL3, respectively. The terminals P2 and N2 are connected to the power lines PL2 and NL2, respectively.

[0017] The relay circuit 115 is provided between the battery 102 and the drive device 105. The relay circuit 115 includes terminals P3, P4, N3, and N4. The terminals P3 and N3 are connected to the power lines PL2 and NL2, respectively. The terminals P4 and N4 are connected to the power lines PL1 and NL1, respectively.

[0018] Each of the relay circuits 110, 115 includes a plurality of contact relays (described later). The relay circuit 110 is made conductive during power transmission between the vehicle 10 and the power equipment 20. The relay circuit 115 is made conductive during driving of the vehicle 10, and is also made conductive during power transmission. The power transmission may be either external charging, in which the battery 102 is charged using power supplied from the power equipment 20, or external discharging, in which the discharged power of the battery 102 is discharged outside the vehicle 10. In this example, the power supply is DC power, so external charging is also referred to as "DC charging". In the following description, DC charging is used as an example of power transmission.

[0019] Voltage sensor 150 detects voltage VI between power lines PL3 and NL3. Capacitor 155 is connected between a pair of power lines consisting of power lines PL2 and NL2. Before the start of DC charging, capacitor 155 is precharged with power from battery 102 to prevent inrush current at the start of DC charging. Voltage sensor 160 detects voltage VH across capacitor 155. Voltage VH corresponds to the voltage between power lines PL2 and NL2.

[0020] The ECU 180 includes a processor and a memory (neither shown). The processor is, for example, a CPU (Central Processing Unit) and executes various types of arithmetic processing. The memory includes a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM stores programs executed by the processor.

[0021] The ECU 180 controls various devices of the vehicle 10 in accordance with detection values ​​of various physical quantities such as the voltages VI and VH. The devices include a drive unit 105 and relay circuits 110 and 115.

[0022] With the connector 210 connected to the inlet 104, the ECU 180 establishes a communication connection with the power equipment 20, for example, by CAN (Controller Area Network) communication, and transmits and receives various signals. In one example, the ECU 180 uses the signals to start or stop DC charging. When DC charging starts or stops, the ECU 180 notifies control units 126, 136 (described later) of that effect. Before DC charging starts, the ECU 180 exchanges various information (advance information) with the power equipment 20. After completing the exchange of the advance information, the ECU 180 executes a predetermined insulation diagnosis process.

[0023] 2 is a diagram illustrating a detailed configuration of relay circuit 110. Referring to FIG. 2, relay circuit 110 includes contact relays 120-B and 120-G and a voltage generating circuit 122.

[0024] The contact relays 120-B and 120-G are DC charging relays connected to the power lines PL3 and NL3, respectively. The contact relay 120-B includes an electrical contact RY11 and a coil DCR-B1. The electrical contact RY11 is connected between the power lines PL2 and PL3, and is driven by the coil DCR-B1 using power from an auxiliary battery 128 (described later). For example, when the applied voltage V11 to the coil DCR-B1 exceeds the operating voltage of the contact relay 120-B, the electrical contact RY11 is closed. When the applied voltage V11 falls below the return voltage of the contact relay 120-B, the electrical contact RY11 is opened. The return voltage is higher than zero voltage (0V) and lower than the operating voltage.

[0025] The contact relay 120-G includes an electrical contact RY12 and a coil DCR-G1. The electrical contact RY12 is connected between the power lines NL2 and NL3, and is driven by the coil DCR-G1 using the power of the auxiliary battery 128. For example, when the voltage V12 applied to the coil DCR-G1 exceeds the operating voltage of the contact relay 120-G, the electrical contact RY12 is closed. When the applied voltage V12 falls below the release voltage of the contact relay 120-G, the electrical contact RY12 is opened. The operating voltage and release voltage of the contact relay 120-G are equal to the operating voltage and release voltage of the contact relay 120-B, respectively.

[0026] The voltage generation circuit 122 includes a voltage generation unit 124 and a control unit 126. The voltage generation unit 124 is connected to each of the coils DCR-B1, DCR-G1, and generates applied voltages V11, V12. The voltage generation unit 124 includes an auxiliary battery 128, a step-down converter 129, a diode D1, resistors R10 to R12, and switching elements Q10 to Q12, M10 to M12.

[0027] The auxiliary battery 128 functions as a power supply node for low-voltage systems such as the voltage generating circuit 122, and generates a power supply voltage VBB. The power supply voltage VBB is higher than the operating voltage of the contact relays 120-B and 120-G.

[0028] The step-down converter 129 is a DC / DC converter that converts the power supply voltage VBB into a step-down voltage VCC and outputs it. The step-down voltage VCC is lower than the operating voltages of the contact relays 120-B and 120-G and higher than the release voltages of these contact relays.

[0029] The step-down converter 129 includes an input terminal Te1, an output terminal Te2, a switching element 129Q, a diode 129D, and an inductor 129L. The input terminal Te1 is connected to the auxiliary battery 128. The output terminal Te2 is connected to the anode of the diode D1. A current flows through the diode D1 only when the anode side potential (step-down voltage VCC) is higher than the cathode side potential. The voltage drop of the diode D1 is assumed to be negligibly small. One main electrode of the switching element 129Q is connected to the positive electrode of the auxiliary battery 128 through the input terminal Te1. The other main electrode of the switching element 129Q is connected to the inductor 129L and the cathode of the diode 129D. The switching element 129Q is driven (on / off) by the control unit 126.

[0030] Each of the switching elements Q10 to Q12 is a bipolar transistor. Each of the switching elements M10 to M12 is a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET).

[0031] The control unit 126 controls the on / off state of the switching elements Q10 to Q12 according to a command from the ECU 180. When the control unit 126 turns on the switching element Q10, the power supply voltage VBB is applied to the resistor R10. In this case, the switching element M10 is conductive. Then, when the control unit 126 turns on the switching element Q11, the power supply voltage VBB is applied to the resistor R11. In this case, the switching element M11 is conductive, and the coil DCR-B1 is electrically connected to the auxiliary battery 128. As a result, the applied voltage V11 rises to the power supply voltage VBB, which is higher than the above-mentioned operating voltage. As a result, the electrical contact RY11 is closed. After that, when the control unit 126 turns off both the switching elements Q10 and Q11, the coil DCR-B1 is electrically disconnected from the auxiliary battery 128. As a result, the applied voltage V11 falls below the recovery voltage and drops to zero voltage, and the electrical contact RY11 is opened.

[0032] Similarly, when the control unit 126 turns on the switching element Q12 while the switching element M10 is conductive, the power supply voltage VBB is applied to the resistor R12. In this case, the switching element M12 is conductive, and the coil DCR-G1 is electrically connected to the auxiliary battery 128. This causes the applied voltage V12 to rise to the power supply voltage VBB. As a result, the electrical contact RY12 is closed. After that, when the control unit 126 turns off both the switching elements Q10 and Q12, the applied voltage V12 drops to zero voltage and the electrical contact RY12 is opened.

[0033] It is important to effectively reduce the power consumption of the auxiliary battery 128 when the electrical contacts RY11 and RY12 are driven. The lower the applied voltages V11 and V12, the smaller the power consumption in the coils DCR-B1 and DCR-G1, respectively. On the other hand, if the applied voltages V11 and V12 are too low, the electrical contacts RY11 and RY12 cannot be controlled to be in the closed state. The configuration of the relay circuit 110 for dealing with such a problem will be described below.

[0034] The control unit 126 of the relay circuit 110 controls the voltage generating unit 124 to generate the applied voltage V11 so that the applied voltage V11 exceeds the operating voltage when the electrical contact RY11 is driven, thereby closing the electrical contact RY11. Thereafter, the control unit 126 controls the voltage generating unit 124 to generate the applied voltage V11 so that the applied voltage V11 is lowered to and maintained at an intermediate voltage (in this example, the step-down voltage VCC) within a voltage range that is lower than the above-mentioned operating voltage and higher than the recovery voltage. Similarly, the control unit 126 controls the voltage generating unit 124 to generate the applied voltage V12 so that the applied voltage V12 exceeds the operating voltage when the electrical contact RY12 is driven, thereby closing the electrical contact RY12. Thereafter, the control unit 126 controls the voltage generating unit 124 to generate the applied voltage V12 so that the applied voltage V12 is lowered to and maintained at the step-down voltage VCC.

[0035] With this configuration, the applied voltages V11, V12 are lowered to the step-down voltage VCC and maintained after the electrical contacts RY11, RY12 are closed. Since the step-down voltage VCC is higher than the recovery voltage, the closed state of these electrical contacts is maintained. When the applied voltages V11, V12 are the step-down voltage VCC, the power consumption in the coils DCR-B1, DCR-G1 is smaller than when the applied voltages V11, V12 are the power supply voltage VBB. Therefore, with the above configuration, the power consumption in the coils DCR-B1, DCR-G1 can be reduced while maintaining the closed state of the electrical contacts RY11, RY12. As a result, the power consumption of the auxiliary battery 128 when these electrical contacts are driven during DC charging can be effectively reduced (power efficiency can be improved).

[0036] A method for increasing the applied voltages V11 and V12 to the power supply voltage VBB and then decreasing them to the step-down voltage VCC will be described in more detail below. For example, for the applied voltage V11, the control unit 126 turns on the switching element Q10 and then turns on the switching element Q11 (conducting the switching elements M10 and M11) to electrically connect the auxiliary battery 128 to the coil DCR-B1. As a result, the applied voltage V11 increases to the power supply voltage VBB and the electrical contact RY11 is closed. After that, the control unit 126 turns off the switching element Q10 to electrically connect the output terminal Te2 of the step-down converter 129 to the coil DCR-B1 instead of the auxiliary battery 128 through the diode D1. As a result, the applied voltage V11 decreases to the step-down voltage VCC.

[0037] Similarly, for the applied voltage V12, the control unit 126 turns on the switching element Q12 after turning on the switching element Q10 (conducting the switching elements M10 and M12) to electrically connect the auxiliary battery 128 to the coil DCR-G1. As a result, the applied voltage V12 rises to the power supply voltage VBB and the electrical contact RY12 is closed. After that, the control unit 126 turns off the switching element Q10 to electrically connect the output terminal Te2 of the step-down converter 129 to the coil DCR-G1 instead of the auxiliary battery 128 through the diode D1. As a result, the applied voltage V12 drops to the step-down voltage VCC.

[0038] When the auxiliary battery 128 is electrically connected to the coils DCR-B, DCR-G, each of the applied voltages V11, V12 is the power supply voltage VBB. When the connection destination of each of the coils DCR-B, DCR-G is switched from the auxiliary battery 128 to the output terminal Te2 of the step-down converter 129, each of the applied voltages V11, V12 drops from the power supply voltage VBB to the step-down voltage VCC. Therefore, by switching the connection destination of each coil as described above, it is possible to easily maintain the applied voltages V11, V12 within a voltage range that is less than the operating voltage and equal to or greater than the recovery voltage.

[0039] 3 is a timing chart for specifically illustrating the transition of applied voltages V11, V12 in the embodiment. From the top, the diagram shows the on / off states of switching elements Q10-Q12, applied voltages V11, V12, and the open / closed states of electrical contacts RY11, RY12.

[0040] 3, in the period from time t0 to time t1, connector 210 is connected to inlet 104, and the above-mentioned advance information is exchanged between ECU 180 and power equipment 20. Then, a user operation to lock connector 210 is performed, and insulation diagnosis processing is started. In the period from time t0 to time t1, switching elements Q10 to Q12 are in the off state, and applied voltages V11, V12 are zero voltage. Therefore, electrical contacts RY11, RY12 are in the open state.

[0041] At time t1, the control unit 126 turns on the switching elements Q10 to Q12. As a result, the coils DCR-B1 and DCR-G1 are electrically connected to the auxiliary battery 128, and the applied voltages V11 and V12 rise from zero voltage to the power supply voltage VBB. As a result, the electrical contacts RY11 and RY12 are closed.

[0042] At time t2, DC charging starts, and the control unit 126 turns off the switching element Q10. This switches the connection of each coil from the auxiliary battery 128 to the output terminal Te2 of the step-down converter 129, and the applied voltages V11, V12 drop from the power supply voltage VBB to the step-down voltage VCC. During the period from time t2 to time t4 (period TP1), each of these applied voltages is maintained at the step-down voltage VCC, so that the electrical contacts RY11, RY12 remain closed. At time t4p, a predetermined time before time t4, the DC charging stops.

[0043] At time t4, the control unit 126 turns off the switching elements Q11 and Q12. This causes the switching elements M11 and M12 to no longer conduct. As a result, each coil is electrically disconnected from the step-down converter 129, and the applied voltages V11 and V12 drop below the recovery voltage to zero. This causes the electrical contacts RY11 and RY12 to open.

[0044] During the period from time t5 to time t7, ECU 180 executes a welding diagnosis process for diagnosing whether or not electrical contacts RY11, RY12 are welded, in accordance with voltage VH.

[0045] After time t7, the ECU 180 checks the voltage VI and terminates communication with the power equipment 20. The connector 210 is pulled out from the inlet 104 after a user operation to unlock the connector 210.

[0046] Fig. 4 is a flowchart illustrating a process executed by the control unit 126. This flowchart starts after the advance information is exchanged (at time t1 in Fig. 3).

[0047] 4, the control unit 126 turns on the switching elements Q11 and Q12 (S105), so that the applied voltages V11 and V12 exceed the operating voltage and rise to the power supply voltage VBB, and the electrical contacts RY11 and RY12 are closed.

[0048] Control unit 126 determines whether DC charging has started according to a notification from ECU 180 (S115). If DC charging has not started yet (NO in S115), the process returns to S105, and applied voltages V11 and V12 are held at power supply voltage VBB. If DC charging has started (YES in S115), the process proceeds to S120.

[0049] When DC charging starts, the control unit 126 turns off the switching element Q10 while maintaining the on state of the switching elements Q11 and Q12 (S120). As a result, the applied voltages V11 and V12 drop to the step-down voltage VCC, but the closed state of the electrical contacts RY11 and RY12 is maintained.

[0050] The control unit 126 determines whether or not DC charging has stopped according to a notification from the ECU 180 (S125). If DC charging has not yet stopped (NO in S125), the process returns to S120, and the applied voltages V11 and V12 are held at the stepped-down voltage VCC. If DC charging has stopped (YES in S125), the control unit 126 waits for a predetermined period of time, and then turns off the switching elements Q11 and Q12 at time t4 (S130). This causes the applied voltages V11 and V12 to drop to zero voltage, and the electrical contacts RY11 and RY12 are opened. The process then ends.

[0051] The vehicle 10 can perform DC charging by establishing an electrical connection between the vehicle 10 and the power equipment 20. To establish the electrical connection, the electrical contacts RY11, RY12 of the relay circuit 110 must be in a closed state. According to the embodiment, it is possible to effectively reduce the power consumption of the auxiliary battery 128 when these electrical contacts are controlled to be in a closed state (e.g., during the period TP1). Furthermore, it is possible to avoid a situation in which the power of the auxiliary battery 128 is exhausted due to the power consumption in the low-voltage system of the vehicle 10 after the end of DC charging.

[0052] [Variations] In this modification, a control for reducing power consumption when driving the electrical contacts of the relay circuit 115 (FIG. 1) is described. As described below, the above-described voltage control for the contact relays 120-B and 120-G can also be applied to each contact relay of the relay circuit 115.

[0053] Fig. 5 is a diagram showing a detailed configuration of relay circuit 115. Referring to Fig. 5, relay circuit 115 differs from relay circuit 110 (Fig. 2) in that relay circuit 115 includes contact relays 130-B, 130-G and a voltage generating circuit 132 instead of contact relays 120-B, 120-G and voltage generating circuit 122. Relay circuit 115 further differs from relay circuit 110 in that relay circuit 115 includes contact relay 130-P and a resistive element RP.

[0054] Each of the contact relays 130-B, 130-G, and 130-P is a system main relay provided on an electric path between the battery 102 and the drive device 105. The contact relay 130-B includes an electrical contact RY21 and a coil DCR-B2. The contact relay 130-G includes an electrical contact RY22 and a coil DCR-G2. The contact relay 130-P includes an electrical contact RY23 and a coil DCR-P2. The voltages applied to the coils DCR-B2, DCR-G2, and DCR-P2 are also referred to as applied voltages V21, V22, and V23, respectively.

[0055] The electrical contact RY21 is connected between the power lines PL1 and PL2. The electrical contact RY22 is connected between the power lines NL1 and NL2. The electrical contact RY23 is provided in parallel with the electrical contact RY22 and is connected to the power line NL1 through a resistive element RP. The resistive element RP is connected to the electrical contact RY23 and is provided as a discharge resistor for precharging the capacitor 155 (FIG. 1).

[0056] The electrical contact RY21 is driven by the coil DCR-B2 according to the applied voltage V21. The electrical contact RY22 is driven by the coil DCR-G2 according to the applied voltage V22. The electrical contact RY23 is driven by the coil DCR-P2 according to the applied voltage V23.

[0057] For example, when the applied voltage V21 exceeds the operating voltage of contact relay 130-B, electrical contact RY21 is closed. When the applied voltage V21 falls below the release voltage of contact relay 130-B, electrical contact RY21 is opened. Similarly, when the applied voltages V22 and V23 exceed the operating voltage of contact relay 130-G and the operating voltage of contact relay 130-P, respectively, electrical contacts RY22 and RY23 are closed. When the applied voltages V22 and V23 fall below the release voltage of contact relay 130-G and the release voltage of contact relay 130-P, respectively, electrical contacts RY22 and RY23 are opened.

[0058] The operating voltages of the contact relays 130-B, 130-G, and 130-P are equal to each other and are the same as the operating voltages of the contact relays 120-B and 120-G (FIG. 2). Similarly, the release voltages of the contact relays 130-B, 130-G, and 130-P are equal to each other and are the same as the release voltages of the contact relays 120-B and 120-G.

[0059] The voltage generation circuit 132 includes a voltage generation unit 134 and a control unit 136. The voltage generation unit 134 is connected to each of the coils DCR-B2, DCR-G2, and DCR-P2, and is configured to generate applied voltages V21, V22, and V23. The voltage generation unit 124 includes an auxiliary battery 138, a step-down converter 139, a diode D11, resistors R20 to R23, and switching elements Q20 to Q23, and M20 to M23.

[0060] The auxiliary battery 138, the step-down converter 139, and the diode D11 are the same as the auxiliary battery 128, the step-down converter 129, and the diode D1 (all of which are shown in FIG. 2). Each of the switching elements Q20 to Q23 is a bipolar transistor. Each of the switching elements M20 to M23 is a MOSFET.

[0061] The control unit 136 controls the on / off states of the switching elements Q20 to Q23 according to the commands from the ECU 180. When the control unit 136 turns on the switching element Q10, the power supply voltage VBB is applied to the resistor R20. In this case, the switching element M20 conducts. Then, when the control unit 136 turns on the switching element Q21, the power supply voltage VBB is applied to the resistor R21. In this case, the switching element M21 conducts, and the coil DCR-B2 is electrically connected to the auxiliary battery 138. As a result, the applied voltage V21 rises to the power supply voltage VBB, which is higher than the operating voltage. Consequently, the electrical contact RY21 is closed. After that, when the control unit 136 turns off both the switching elements Q20 and Q21, the coil DCR-B2 is electrically disconnected from the auxiliary battery 138. Thereby, the applied voltage V21 drops below the return voltage and decreases to zero voltage, and the electrical contact RY21 is opened.

[0062] Similarly, when the control unit 136 turns on the switching element Q22 while the switching element M20 is conducting, the power supply voltage VBB is applied to the resistor R22. In this case, the switching element M22 conducts, and the coil DCR-G2 is electrically connected to the auxiliary battery 138. Thereby, the applied voltage V22 rises to the power supply voltage VBB. As a result, the electrical contact RY22 is closed. After that, when the control unit 136 turns off both the switching elements Q20 and Q22, the applied voltage V22 decreases to zero voltage and the electrical contact RY22 is opened.

[0063] Similarly, when the control unit 136 turns on the switching element Q23 while the switching element M20 is conducting, the power supply voltage VBB is applied to the resistor R23. In this case, the switching element M23 is conducting, and the coil DCR-P2 is electrically connected to the auxiliary battery 138. This causes the applied voltage V23 to rise to the power supply voltage VBB. As a result, the electrical contact RY23 is closed. When the control unit 136 subsequently turns off both the switching elements Q20 and Q23, the applied voltage V23 drops to zero voltage and the electrical contact RY23 is opened. When the electrical contacts RY21 and RY23 are closed before the start of DC charging, the capacitor 155 is precharged. After the precharge of the capacitor 155 is completed, the electrical contact RY22 is closed and the electrical contact RY23 is opened, and DC charging is started.

[0064] The control unit 136 executes voltage control for each of the electrical contacts RY21 and RY22 in the same manner as the control unit 126 in the embodiment. This point will be specifically described below.

[0065] 6 is a timing diagram specifically illustrating the transitions of applied voltages V21, V22, and V23 in this modified example. From the top, this diagram represents the on / off states of switching elements Q20-Q23, applied voltages V21-V23, and the open / closed states of electrical contacts RY21-RY23.

[0066] 6, at time t11 after time t10, the above-mentioned exchange of advance information is started, and the control unit 136 turns on the switching elements Q20, Q21, and Q23. This causes the switching elements M20, M21, and M23 to conduct. As a result, the coils DCR-B2 and DCR-P2 are electrically connected to the auxiliary battery 138, and the applied voltages V21 and V23 rise from zero voltage to the power supply voltage VBB. As a result, the electrical contacts RY21 and RY23 are closed. During the period TPP (time t11 to time t12), these contacts remain closed, and the capacitor 155 is precharged.

[0067] At time t12, the voltage VH reaches a predetermined threshold voltage, and the precharging of the capacitor 155 is completed. The control unit 136 turns on the switching element Q22 and turns off the switching element Q23. This causes the switching element M22 to be conductive, while the switching element M23 is no longer conductive. As a result, the coil DCR-G2 is connected to the auxiliary battery 138, and the coil DCR-P2 is electrically disconnected from the auxiliary battery 138. As a result, the applied voltage V22 rises from zero voltage to the power supply voltage VBB, and the applied voltage V23 drops from the power supply voltage VBB to zero voltage. Therefore, the electrical contact RY22 is closed, and the electrical contact RY23 is opened.

[0068] At time t13, when DC charging starts, the control unit 136 controls the voltage generating unit 134 to generate the applied voltages V21, V22 so that each of the applied voltages V21, V22 is lowered to and maintained at the step-down voltage VCC. As a specific example, the control unit 136 turns off the switching element Q20. This switches the connection destination of each of the coils DCR-B2, DCR-G2 from the auxiliary battery 138 to the output terminal Te12 of the step-down converter 139. As a result, the applied voltages V11, V12 are lowered from the power supply voltage VBB to the step-down voltage VCC. During the period TP2 (time t13 to time t18), each of these applied voltages is maintained at the step-down voltage VCC, so that the electrical contacts RY21, RY22 remain in the closed state. As a result, during the period TP2, the power consumption in the coils DCR-B2, DCR-G2 (power consumption of the auxiliary battery 138) can be reduced with these electrical contacts maintained in the closed state.

[0069] At time t18, the control unit 136 turns off the switching elements Q21 and Q22. This electrically disconnects the coils DCR-B2 and DCR-G2 from the step-down converter 139, and the applied voltages V21 and V22 drop from the step-down voltage VCC to zero. As a result, the electrical contacts RY21 and RY22 are opened.

[0070] As described below, the control unit 136 may control the voltage generating unit 134 so that each of the applied voltages V21, V23 is lowered from the power supply voltage VBB to the step-down voltage VCC and maintained during the period TPP (applied voltage control during the precharge period). Specifically, the control unit 136 may turn off the switching element Q20 while the switching element M10 is in a conductive state during the period TPP. This causes the connection destination of each of the coils DCR-B2, DCR-P2 to be switched from the auxiliary battery 138 to the output terminal Te12 of the step-down converter 139, and each of the applied voltages V21, V23 is lowered to the step-down voltage VCC.

[0071] Thereafter, just before time t12 (the reference time before), the control unit 136 turns on the switching element Q20 again to make the switching element M10 conductive again. This switches the connection destination of each of the coils DCR-B2, DCR-P2 from the output terminal Te12 to the auxiliary battery 138 again, and each of the applied voltages V21, V23 rises again from the step-down voltage VCC to the power supply voltage VBB. After the arrival of time t12, the control unit 136 executes the above-mentioned control of the switching elements Q20 to Q23 after time t12.

[0072] With this configuration, it is possible to reduce power consumption in the coils DCR-B2, DCR-P2 while the electrical contacts RY21, RY23 are maintained in a closed state during the period TPP. The above-mentioned applied voltage control is more effective the longer the period TPP is (or the longer the period during which the applied voltages V21, V23 are held at the step-down voltage VCC). Therefore, the control unit 136 may execute the above-mentioned applied voltage control when the period TPP is longer than a predetermined threshold time.

[0073] As described above, according to this modification, it is possible to reduce power consumption of the auxiliary battery 138 when driving the electrical contacts RY21, RY22, RY23 of the relay circuit 115 for DC charging or the like.

[0074] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0075] 10 vehicle, 102 battery, 104 inlet, 105 drive unit, 110,115 relay circuit, 120,130 contact relay, 122,132 voltage generation circuit, 128,138 auxiliary battery, 129,139 step-down converter, 155 capacitor.

Claims

1. A contact relay including an electrical contact and a coil for driving the electrical contact; a voltage generating circuit connected to the coil and generating a voltage to be applied to the coil; The electrical contacts are closed when the applied voltage exceeds a first voltage; When the applied voltage falls below a second voltage that is lower than the first voltage, the switch is released. the voltage generating circuit generates the applied voltage such that the applied voltage exceeds the first voltage to close the electrical contact, and then generates the applied voltage such that the applied voltage drops to and is maintained at a third voltage that is less than the first voltage and higher than the second voltage.

2. The voltage generating circuit includes: a power supply node generating a power supply voltage higher than the first voltage; a converter having an input terminal connected to the power supply node, the converter converting the power supply voltage into the third voltage and outputting the third voltage; The relay circuit according to claim 1 , wherein the voltage generating circuit is configured to connect the power supply node to the coil, and then connect an output terminal of the converter to the coil instead of the power supply node.

3. A vehicle, The relay circuit according to claim 1 or 2, an inlet connectable to an electric power facility provided outside the vehicle; The contact relay is connected to a power line connected to the inlet.

4. A vehicle, The relay circuit according to claim 1 or 2, A power storage device that stores power for driving the vehicle; a drive device that generates a driving force for the vehicle, The contact relay is provided on an electric path between the power storage device and the drive device.

5. The vehicle is configured to be able to transmit power between an electric power facility external to the vehicle and the vehicle; the vehicle further includes a capacitor connected between a first high potential side power line and a first low potential side power line, each of which is connected to the drive device; the contact relays include a first contact relay, a second contact relay, and a third contact relay; the first contact relay includes a first contact as the electrical contact connected between a second high potential side power line connected to a positive electrode of the power storage device and the first high potential side power line, and a first coil that drives the first contact, the second contact relay includes a second contact as the electrical contact connected between a second low potential side power line connected to a negative electrode of the power storage device and the first low potential side power line, and a second coil that drives the second contact, the third contact relay includes a third contact as the electrical contact connected to the second low potential side power line through a resistive element for precharging the capacitor, and a third coil for driving the third contact, the voltage generation circuit generates a first applied voltage as the applied voltage to the first coil, a second applied voltage as the applied voltage to the second coil, and a third applied voltage as the applied voltage to the third coil; the capacitor is precharged when the first contact and the third contact are closed before the power transfer begins; the power transfer is initiated when the second contact is closed and the third contact is opened after completion of precharging of the capacitor; The voltage generating circuit includes: generating the first applied voltage and the third applied voltage such that each of the first applied voltage and the third applied voltage is lowered to and held at the third voltage during precharging of the capacitor; 5. The vehicle according to claim 4, wherein when the power transmission starts, the first applied voltage and the second applied voltage are generated such that each of the first applied voltage and the second applied voltage is lowered to and maintained at the third voltage.

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