Electric vehicles

Abstract

To prevent a voltage from generating in an electric circuit including a drive device due to a leakage current of a converter at the time of disconnecting a relay for connecting / disconnecting between a power storage device and the drive device.SOLUTION: An electric vehicle raises a voltage of an auxiliary battery 140 with a bidirectional DCDC converter 130 to pre-charge a power line PL and a power line NL in the connection processing of an SMR11 and an SMR12 for connecting / disconnecting between a battery 10 and a PCU20. During the pre-charge, the electric vehicle activates a bidirectional charger 110 connected to the power line PL and the power line NL.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to electric vehicles. [Background technology]

[0002] For example, the electric vehicle described in JP 2013-240191 A (Patent Document 1) is equipped with a power conversion device that outputs power input from an inlet to a power storage device and outputs power input from the power storage device to an outlet. In this Patent Document 1, a system main relay (hereinafter also referred to as SMR (System Main Relay)) is provided that connects the power storage device and a PCU (Power Control Unit), and the power conversion device is connected to a power line between the SMR and the PCU. The PCU includes an inverter and is a drive device that drives a motor generator using power from the power storage device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-240191 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the electric vehicle disclosed in the above-mentioned Patent Document 1, when the SMR is cut off and power from the power storage device is not being supplied to the PCU, starting up the power conversion device (hereinafter also referred to as the "converter") may cause a voltage to be generated in an electric circuit including the PCU due to leakage current from a driver (drive circuit) of a switching element constituting the converter. Since the SMR is in a cut-off state, if abnormality detection of the electric circuit or offset learning (zero point correction) of various sensors is performed on the assumption that no voltage is generated in the electric circuit including the PCU, if a voltage is generated in the electric circuit due to leakage current from the driver of the switching element, this may lead to erroneous detection or erroneous learning.

[0005] An object of the present disclosure is to prevent a voltage from being generated in an electric circuit including the drive device due to a leakage current of a converter when a relay that connects / disconnects between an electricity storage device and a drive device is disconnected. [Means for solving the problem]

[0006] The electric vehicle of the present disclosure is an electric vehicle including a power storage device, an electric motor that drives drive wheels, a drive device that drives the electric motor using power from the power storage device, a relay that connects / disconnects between the power storage device and the drive device, a converter that is connected to a power line between the relay and the drive device and converts AC power supplied from an external power source into DC power to charge the power storage device, and a control device. The control device starts or stops the converter when a voltage is applied to the power line to which the converter is connected.

[0007] According to this configuration, the converter is connected to a power line between the drive device and a relay that connects / disconnects the power storage device and the drive device. The converter converts AC power supplied from an external power source into DC power and charges the power storage device. The control device starts the converter when a voltage is applied to the power line to which the converter is connected. Alternatively, the control device stops the converter when a voltage is applied to the power line to which the converter is connected.

[0008] The electric vehicle of the present disclosure is an electric vehicle including a power storage device, an electric motor that drives drive wheels, a drive device that drives the electric motor using power from the power storage device, a relay that connects / disconnects between the power storage device and the drive device, a converter that is connected to a power line between the relay and the drive device and that converts DC power from the power storage device into AC power and outputs it to an outlet, and a control device. The control device starts or stops the converter when a voltage is applied to the power line to which the converter is connected.

[0009] According to this configuration, the converter is connected to a power line between the drive device and a relay that connects / disconnects the power storage device and the drive device. The converter converts DC power from the power storage device into AC power and outputs it to an outlet. The control device starts the converter when a voltage is applied to the power line to which the converter is connected. Alternatively, the control device stops the converter when a voltage is applied to the power line to which the converter is connected.

[0010] The electric vehicle disclosed herein is an electric vehicle including a power storage device, an electric motor that drives drive wheels, a drive device that drives the electric motor using power from the power storage device, a relay that connects / disconnects between the power storage device and the drive device, a converter that is connected to a power line between the relay and the drive device and that converts AC power supplied from an external power source into DC power to charge the power storage device, and a control device. The converter is configured to convert DC power from the power storage device into AC power and output it to an outlet. The control device starts or stops the converter when a voltage is applied to the power line to which the converter is connected.

[0011] According to this configuration, the converter is connected to a power line between the drive device and a relay that connects / disconnects the power storage device and the drive device. The converter is capable of converting AC power supplied from an external power source into DC power to charge the power storage device, and converting DC power from the power storage device into AC power to output to an outlet. The control device starts the converter when a voltage is applied to the power line to which the converter is connected. Alternatively, the control device stops the converter when a voltage is applied to the power line to which the converter is connected.

[0012] In the above configuration, the converter is started when a voltage is applied to the power line to which the converter is connected (the power line between the relay and the drive device). Even if a leakage current occurs from the converter due to the start of the converter, a voltage is applied to the power line to which the converter is connected, so that it is possible to suppress an increase in the voltage of the power line due to the leakage current. Therefore, when the relay that connects / disconnects between the power storage device and the drive device is disconnected and no voltage is applied to the power line, the converter is not started, so that it is possible to suppress the generation of a voltage in an electric circuit including the drive device due to the leakage current of the converter.

[0013] In the above configuration, the converter is stopped when a voltage is applied to the power line to which the converter is connected. Therefore, before the converter is stopped and the converter is activated, when there is a possibility of a leak current from the converter, a voltage is applied to the power line to which the converter is connected, so that even if a leak current occurs from the converter, it is possible to suppress the voltage on the power line from increasing due to the leak current. Furthermore, when a relay that connects / disconnects between the power storage device and the drive device is disconnected and no voltage is applied to the power line, the converter is stopped, so it is possible to suppress the generation of a voltage in an electric circuit including the drive device due to the leak current of the converter. Therefore, when the relay that connects / disconnects between the power storage device and the drive device is disconnected, it is possible to suppress the generation of a voltage in an electric circuit including the drive device due to the leak current of the converter.

[0014] Preferably, the electric vehicle further includes an auxiliary battery that supplies power to the auxiliary device, and a bidirectional DC-DC converter that exchanges power between the auxiliary battery and the power line. The control device executes a connection process for switching the relay from a cut-off state to a connection state, and the connection process may include a process for boosting the power of the auxiliary battery by the bidirectional DC-DC converter to increase the voltage of the power line, starting the converter, and switching the relay from the cut-off state to the connection state after the voltage of the power line has increased to a predetermined value.

[0015] According to this configuration, the control device executes a connection process for switching the relay from a cutoff state to a connected state. The connection process includes a process of boosting the power of the auxiliary battery by the bidirectional DC-DC converter to increase the voltage of the power line and starting the converter, and switching the relay from a cutoff state to a connected state after the voltage of the power line has increased to a predetermined value.

[0016] In the connection process, the bidirectional DC-DC converter boosts the power of the auxiliary battery to increase the voltage of the power line and starts the converter, and after the voltage of the power line has increased to a predetermined value, the relay is switched from a cut-off state to a connected state. When the relay that connects / disconnects between the power storage device and the drive device is cut off, the converter is in a stopped state, and no voltage is generated in the power line to which the converter is connected due to leakage current from the converter.

[0017] When the converter is not activated, the converter is in an unstable state and there is a possibility of an unintended short circuit or malfunction due to noise, etc. With this configuration, the converter is activated when the relay is in a connected state and the voltage of the power storage device is applied to the power line, so that it is possible to suppress a short circuit or malfunction of the converter when a voltage is applied to the power line to which the converter is connected (the power line between the relay and the drive device).

[0018] Preferably, the electric vehicle further includes an auxiliary battery that supplies power to the auxiliary device, and a bidirectional DC-DC converter that exchanges power between the auxiliary battery and the power line. The control device executes a disconnection process for switching the relay from a connected state to a disconnected state, and the disconnection process may include a process of, after switching the relay from a connected state to a disconnected state, supplying power from the power line to the auxiliary battery by the bidirectional DC-DC converter to reduce the voltage of the power line and stopping the converter.

[0019] According to this configuration, the control device executes a disconnection process for switching the relay from a connected state to a disconnected state. The disconnection process includes a process of supplying power from the power line to the auxiliary battery by the bidirectional DC-DC converter to reduce the voltage of the power line and stopping the converter after switching the relay from a connected state to a disconnected state.

[0020] In the disconnection process, after switching the relay from a connected state to a disconnected state, the bidirectional DC-DC converter supplies power from the power line to the auxiliary battery to lower the voltage on the power line, and the converter is stopped. When the relay that connects / disconnects between the power storage device and the drive device is disconnected, the converter is stopped, and no voltage is generated in the power line to which the converter is connected due to leakage current from the converter. In addition, when the relay is connected and the voltage of the power storage device is applied to the power line, the converter is activated, so that it is possible to suppress short circuits and malfunctions of the converter when voltage is applied to the power line.

[0021] Preferably, the relay includes a first relay for connecting / disconnecting one pole of the power storage device and the drive device, a circuit having a limiting resistor connected in series with the first relay, a second relay connected in parallel with the circuit, and a third relay for connecting / disconnecting the other pole of the power storage device and the drive device. The control device executes a connection process for switching the relay from a disconnected state to a connected state. The connection process may include a process for performing a pre-charge process for switching the first relay and the third relay from a disconnected state to a connected state, starting the converter, and, after the pre-charge process is completed, switching the second relay from a disconnected state to a connected state and switching the first relay to the disconnected state.

[0022] According to this configuration, in the connection process, a precharge process is performed to switch the first relay and the third relay from a cutoff state to a connection state. The control device starts up the converter together with the precharge process, and after the precharge process is completed, the control device switches the second relay from a cutoff state to a connection state and the first relay to a cutoff state, and then terminates the connection process.

[0023] In the connection process, the precharge process increases the voltage of the power line to which the converter is connected (the power line between the relay and the drive device) and starts the converter, and after the precharge process is completed, the second relay is switched from a cut-off state to a connected state and the first relay is switched to a cut-off state, and the connection process is completed. When the relay that connects / disconnects between the storage device and the drive device is cut off, the converter is in a stopped state and no voltage is generated in the power line to which the converter is connected due to leakage current from the converter.

[0024] When the converter is not activated, the converter is in an unstable state and there is a possibility of an unintended short circuit or malfunction due to noise, etc. With this configuration, when the relay is in a connected state and the voltage of the power storage device is applied to the power line, the converter is activated, and therefore it is possible to suppress a short circuit or malfunction of the converter when a voltage is applied to the power line.

[0025] Preferably, the control device executes a disconnection process for switching the relay from a connected state to a disconnected state, and the disconnection process may include a process for switching the relay that connects / disconnects one pole of the storage device and the drive device from a connected state to a disconnected state, and after a predetermined period of time has elapsed, switching the relay that connects / disconnects the other pole of the storage device and the drive device from a connected state to a disconnected state, and stopping the converter for the predetermined period of time.

[0026] According to this configuration, the control device executes a disconnection process for switching the relay from a connected state to a disconnected state. In the disconnection process, the relay for connecting / disconnecting one pole of the power storage device and the drive device is switched from a connected state to a disconnected state, and after a predetermined period of time has elapsed, the relay for connecting / disconnecting the other pole of the power storage device and the drive device is switched from a connected state to a disconnected state. Then, during the predetermined period of the disconnection process, the converter is stopped. When both poles of the power storage device and the drive device are disconnected, the converter is in a stopped state, and no voltage is generated in the power line to which the converter is connected due to a leakage current from the converter. In addition, when the relay is in a connected state and the voltage of the power storage device is applied to the power line, the converter is activated, so that it is possible to suppress a short circuit or malfunction of the converter when a voltage is applied to the power line.

[0027] Each of the above control devices may be configured to execute an abnormality detection process for the drive device, or an offset correction process for a sensor provided in an electrical circuit including the drive device, when all of the relays that connect / disconnect between the storage device and the drive device are in a disconnected state.

[0028] Assuming that no voltage is generated in the electrical circuit including the drive device, when all of the relays connecting / disconnecting between the storage device and the drive device are in the disconnected state, if an abnormality detection process for the drive device or an offset correction process for a sensor provided in the electrical circuit including the drive device is performed, if a voltage is generated in the electrical circuit due to leakage current from the converter, this may result in erroneous detection or erroneous correction.

[0029] According to this configuration, when the relay is in the cut-off state, the converter is in a stopped state, and no voltage is generated in the power line to which the converter is connected due to leakage current from the converter. Therefore, even if an abnormality detection process or an offset correction process is performed, erroneous detection and erroneous correction can be suppressed, assuming that no voltage is generated in the electric circuit including the drive device. Effect of the Invention

[0030] According to the present disclosure, when a relay that connects / disconnects between an electricity storage device and a drive device is disconnected, it is possible to prevent a voltage from being generated in an electric circuit including the drive device due to a leakage current from the converter. [Brief description of the drawings]

[0031] [Figure 1] 1 is a diagram showing a configuration of an electric vehicle according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating an example of a circuit configuration of a bidirectional charger. [Diagram 3] FIG. 2 is a diagram illustrating an example of a drive circuit for a switching element. [Figure 4] 4 is a time chart illustrating an SMR connection process in the first embodiment. [Diagram 5] 4 is a flowchart showing an outline of an SMR connection process executed by a control ECU. [Figure 6] 13 is a time chart illustrating an SMR disconnection process in the second embodiment. [Figure 7] 10 is a flowchart showing an outline of an SMR disconnection process executed by a control ECU. [Figure 8] FIG. 4 is a diagram showing a configuration of an electric vehicle according to a first modified example. [Figure 9] 13 is a time chart illustrating an SMR connection process in the first modification example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and the description thereof will not be repeated.

[0033] [Embodiment 1] 1 is a diagram showing a configuration of an electric vehicle V according to a first embodiment of the present disclosure. With reference to FIG 1, the electric vehicle V includes a battery 10, a power control unit (hereinafter also referred to as a “PCU (Power Control Unit)”) 20, a motor generator 30, a differential gear 40, and drive wheels 50.

[0034] The battery 10 is an electricity storage device and is mounted on the electric vehicle V as a driving power source. The battery 10 is configured to include a plurality of stacked single batteries (cells). The battery is, for example, a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The battery may be a battery having a liquid electrolyte between the positive electrode and the negative electrode, or may be a battery having a solid electrolyte (all-solid-state battery).

[0035] The PCU 20 is a drive device that drives the motor generator 30 using the power stored in the battery 10. The battery 10 and the PCU 20 are connected by a power line PL and a power line NL. The positive electrode of the battery 10 and the power line PL are connected via a system main relay (SMR) 11, and the negative electrode of the battery 10 and the power line NL are connected via a system main relay (SMR) 12. The SMR 11 and the SMR 12 may be, for example, electromagnetic mechanical relays. When the SMR 11 and the SMR 12 are in a connected state, power can be exchanged between the battery 10 and the PCU 20, and when the SMR 11 and the SMR 12 are in a cut-off state, power cannot be exchanged between the battery 10 and the PCU 20.

[0036] In this embodiment, the PCU 20 is composed of a DC / DC converter 21 and an inverter 22. The DC / DC converter 21 boosts the DC voltage of the battery 10 and supplies it to the inverter 22. The inverter 22 is a three-phase inverter that converts the DC power supplied from the battery 10 into AC power and drives the motor generator 30. The inverter 22 converts the AC power regenerated by the motor generator 30 into DC power and supplies it to the battery 10 via the DC / DC converter 21. It is noted that the DC / DC converter 21 may be omitted.

[0037] The motor generator 30 is an AC rotating electric machine, which corresponds to the "electric motor" of the present disclosure, and may be, for example, a permanent magnet type synchronous motor having a rotor with a permanent magnet embedded therein. The output shaft of the motor generator 30 is connected to the drive wheels 50 via a differential gear 40, and the drive wheels 50 are driven by the motor generator 30.

[0038] The electric vehicle V is capable of charging the battery 10 using an external power source 200. Charging the battery 10 using the external power source 200 is also referred to as "external charging." The electric vehicle V is provided with an inlet 70, and external charging is performed by connecting a connector 80 of charging equipment (EVSE (Electric Vehicle Supply Equipment) 100) to the inlet 70. The EVSE 100 may be a charging cable with a control function or may be a normal charger. The external power source 200 may be, for example, an AC 200V power source.

[0039] The bidirectional charger 110 is connected to the power line PL (the power line between the SMR 11 and the PCU 20) and the power line NL (the power line between the SMR 12 and the PCU 20). The bidirectional charger 110 converts AC power supplied from the EVSE 100 via the inlet 70 into DC power and charges the battery 10. The bidirectional charger 110 also converts the DC power of the battery 10 into AC power and outputs the AC power to the in-vehicle outlet 120. The bidirectional charger 110 corresponds to the "converter" in this disclosure, and the in-vehicle outlet 120 corresponds to the "outlet" in this disclosure.

[0040] FIG. 2 is a diagram showing an example of a circuit configuration of the bidirectional charger 110. The bidirectional charger 110 includes an inverter 111, an insulating circuit 112, and an inverter 113. The inverter 111 is a full bridge circuit including four switching elements. The insulating circuit 112 is an insulating transformer including a first coil 112a and a second coil 112b. The insulating circuit 112 performs a transformation at a ratio according to a turn ratio between the first coil 112a and the second coil 112b. The inverter 113 includes a first inverter 113a, a second inverter 113b, and a smoothing capacitor 113c. Each of the first inverter 113a and the second inverter 113b is a full bridge circuit including four switching elements. Each switching element included in the inverters 111 and 113 is driven by a driver (drive circuit).

[0041] The inverter 111 is connected to the power lines PL and NL, and the midpoint of the second inverter 113b is connected to the inlet 70 via a relay 115. In addition, the midpoint of the second inverter 113b is connected to the in-vehicle outlet 120 via a relay 116.

[0042] In bidirectional charger 110, when battery 10 is being charged, relay 115 is connected, and second inverter 113b rectifies AC power input from inlet 70 and outputs it to first inverter 113a, and first inverter 113a converts DC power received from second inverter 113b into high-frequency AC power. Isolation circuit 112 transmits the output (AC power) of first inverter 113a to inverter 111, and inverter 111 rectifies the AC power received from isolation circuit 112 and outputs it to power lines PL and NL.

[0043] In bidirectional charger 110, when outputting (power supplying) to in-vehicle outlet 120, relay 116 is connected and inverter 111 converts DC power input from power line PL and power line NL into high-frequency AC power and outputs it to insulation circuit 112. Isolation circuit 112 transmits the output (AC power) of inverter 111 to first inverter 113a, and first inverter 113a rectifies the AC power received from insulation circuit 112 and outputs it to second inverter 113b. Second inverter 113b converts the DC power received from first inverter 113a into a predetermined AC power and outputs it to in-vehicle outlet 120. In-vehicle outlet 120 is an outlet provided in the passenger compartment and having a rated voltage of, for example, AC 100V.

[0044] 1 again, voltage sensor 91 detects voltage VL between power lines PL and NL, and current sensor 92 detects current flowing through power lines PL and NL. A smoothing capacitor C1 is provided between power lines PL and NL to smooth out voltage VL.

[0045] A bidirectional DCDC converter 130 is connected to the power lines PL and NL. The bidirectional DCDC converter 130 steps down the voltage VL (the voltage of the battery 10) and charges the auxiliary battery 140. The bidirectional DCDC converter 130 also steps up the voltage of the auxiliary battery 140 and supplies DC power to the power lines PL and NL. The auxiliary battery 140 is a power source for the auxiliary device 150.

[0046] The control ECU (Electronic Control Unit) 300 controls the SMR 11, the SMR 12, the PCU 20, the bidirectional charger 110, the bidirectional DCDC converter 130, and the like. The control ECU 300 includes a CPU (Central Processing Unit), a memory, and an input / output port (none of which are shown). The memory includes a ROM (Read Only Memory) and a RAM (Random Access Memory) and stores programs executed by the CPU, and the like. The CPU executes a predetermined calculation process based on various signals input from the input / output port, signals from various sensors, and information stored in the memory, and controls each device based on the calculation result so that the electric vehicle V is in a desired state. The control ECU 300 corresponds to the "control device" of this disclosure.

[0047] In this embodiment, signals from a power switch 90, a voltage sensor 91, a current sensor 92, and the like are input to the control ECU 300. The power switch 90 is a switch for starting up the vehicle system. When the power switch 90 is operated while the system is stopped, the vehicle system starts up and the electric vehicle V becomes capable of running. When the power switch 90 is operated while the system is operating, the vehicle system stops and the electric vehicle V becomes unable to run. The power switch 90 is also referred to as an "ignition switch."

[0048] When the bidirectional charger 110 is started, a voltage may be generated in the power lines PL and NL due to a leakage current of a driver (drive circuit) of a switching element of the inverter 111 constituting the bidirectional charger 110. FIG. 3 is a diagram showing an example of a drive circuit 60 for a switching element. FIG. 3 shows one upper and lower arm circuit having an upper arm (high-side switching element) and a lower arm (low-side switching element) in the inverter 111. When using switching elements in the upper and lower arms in a full-bridge circuit or the like, the power supplies of the upper arm (high-side switching element) and the lower arm (low-side switching element) need to be insulated, and in this embodiment, a bootstrap circuit is used.

[0049] 3, a positive voltage power supply 61 is connected to one end of a bootstrap capacitor 65 via a diode 64 through a start-up switch 66. The other end of the bootstrap capacitor 65 is connected to the emitter of a high-side switching element via a resistor. The positive voltage power supply 61 is connected to a high-side gate driver 62 via the start-up switch 66, and the high-side gate driver 62 is connected to the gate of the high-side switching element. The positive voltage power supply 61 is also connected to a low-side gate driver 63 via the start-up switch 66, and the low-side gate driver 63 is connected to the gate of the low-side switching element.

[0050] When the start switch 66 of the drive circuit 60 is turned on to operate the bidirectional charger 110, a current flows from the positive voltage power supply 61 through a path as shown by the dashed arrow in Figure 3, causing a leakage current. This leakage current may cause a voltage to be generated in the power lines PL and NL, even when the SMRs 11 and 12 are in an interrupted state, and a voltage may be generated in an electric circuit including the PCU 20.

[0051] In this embodiment, when the SMR 11 and the SMR 12 are cut off, generation of a voltage in an electric circuit including the PCU 20 due to a leakage current of the bidirectional charger 110 is suppressed.

[0052] 4 is a time chart for explaining the SMR connection process in this embodiment. At time t0, SMR 11 and SMR 12 are in a cutoff state (OFF), and the battery 10 is not connected to the power lines PL and NL. Therefore, the voltage VL is 0 [V]. In addition, the start-up signal of the bidirectional charger 110 is OFF, and the bidirectional charger 110 is in a stopped state.

[0053] When the power switch 90 is operated to start the vehicle system, or when the connector 80 of the EVSE 100 is connected to the inlet 70 to start charging the battery 10, the SMR connection process is started at time t1. When the SMR connection process is started at time t1, the bidirectional DCDC converter 130 boosts the voltage of the auxiliary battery 140, DC power is supplied to the power lines PL and NL, and the voltage VL rises (pre-charge). After a predetermined period has elapsed from time t1, the start-up signal of the bidirectional charger 110 changes from off (OFF) to on (ON), the start-up switch 66 of the drive circuit 60 is turned on (connected), and the bidirectional charger 110 starts up. The predetermined period is a period during which the voltage VL rises due to the operation of the bidirectional DCDC converter 130, and a voltage is reliably applied between the power lines PL and NL, and is set in advance by experiments or the like.

[0054] When the voltage VL rises to almost the voltage (battery voltage) of the battery 10 due to the operation of the bidirectional DC-DC converter 130, the SMR 11 and SMR 12 are switched to the connected state at time t2. The period from time t1 to time t2 is a period during which the voltage VL reliably rises to the battery voltage due to the operation of the bidirectional DC-DC converter 130, and may be determined in advance by an experiment or the like.

[0055] 5 is a flowchart showing an outline of the SMR connection process executed by the control ECU 300. This flowchart is started when the power switch 90 is operated to start up the vehicle system and when the connector 80 of the EVSE 100 is connected to the inlet 70. Before the SMR connection process is started, the SMR 11 and SMR 12 are in a disconnected state (OFF), and the bidirectional charger 110 and the bidirectional DC-DC converter 130 are in a stopped state.

[0056] In step (hereinafter, step is abbreviated as "S") 10, an initialization process is executed. The initialization process includes a diagnosis process for determining whether or not an abnormality has occurred in the PCU 20, the bidirectional charger 110, the bidirectional DCDC converter 130, etc., and an offset correction process (offset value learning process) for the voltage sensor 91 and the current sensor 92. For example, an abnormality diagnosis of the PCU 20 is executed on the premise that the voltage VL is 0 [V]. Also, on the premise that the voltage VL is 0 [V], the offset value (zero point) of the voltage sensor 91 is learned.

[0057] In the next S11, it is determined whether or not an abnormality has been diagnosed in the PCU 20, the bidirectional charger 110, etc., in the abnormality diagnosis of the initialization process. If an abnormality has been diagnosed, a positive determination is made and the current routine is terminated. In this case, the MIL (Malfunction Indicator Lamp) may be turned on to warn the user of the abnormality in the vehicle system. If no abnormality has been diagnosed, a negative determination is made and the routine proceeds to S12.

[0058] In S12, it is determined whether the current process is external charging. When the connector 80 is connected to the inlet 70, it is determined that the current process is external charging (positive determination), and the process proceeds to S13. When the connector 80 is not connected to the inlet 70, a negative determination is made, and the process proceeds to S14.

[0059] In S13, it is determined whether it is time to start external charging. For example, if timer charging is set, it is determined that it is time to start external charging when the charging start time arrives. S13 is repeatedly processed until it is time to start external charging, and when it is time to start external charging, a positive determination is made and the process proceeds to S14.

[0060] In S14, the bidirectional DCDC converter 130 is operated. The bidirectional DCDC converter 130 boosts the voltage of the auxiliary battery 140, supplies DC power to the power lines PL and NL, and raises the voltage VL (pre-charge).

[0061] In the next S15, it is determined whether or not a first predetermined period has elapsed since the bidirectional DC-DC converter 130 was operated. The first predetermined period is a period during which the voltage VL rises due to the operation of the bidirectional DC-DC converter 130, and a voltage is reliably applied between the power lines PL and NL. S15 is repeatedly processed until the first predetermined period has elapsed, and when the first predetermined period has elapsed, a positive determination is made and the process proceeds to S16.

[0062] In S16, the bidirectional charger 110 is started up. The start-up switch 66 of the drive circuit 60 of the bidirectional charger 110 is turned on (connected), thereby starting up the bidirectional charger 110.

[0063] In the next S17, it is determined whether or not a second predetermined period has elapsed since the bidirectional DC-DC converter 130 was operated. The second predetermined period is a period during which the voltage VL reliably rises to the battery voltage due to the operation of the bidirectional DC-DC converter 130. S17 is repeatedly processed until the second predetermined period has elapsed, and when the second predetermined period has elapsed, a positive determination is made and the process proceeds to S18. In S17, it may be determined whether or not the voltage VL has risen to the battery voltage from the output signal of the voltage sensor 91, and when the voltage VL has risen to the battery voltage, a positive determination is made and the process proceeds to S18. Note that the voltage VL at the time the second predetermined period has elapsed may not be the battery voltage, but may be a voltage at which the voltage VL rises due to the operation of the bidirectional DC-DC converter 130 and a large current does not flow through the contacts of the SMRs when the SMRs 11 and 12 are connected.

[0064] In S18, SMR11 and SMR12 are switched to the connected state, and this routine ends.

[0065] In this embodiment, the bidirectional charger 110 is activated when a voltage is applied to the power lines PL and NL by the operation of the bidirectional DC-DC converter 130. This makes it possible to suppress an increase in the voltage of the power lines PL and NL due to a leakage current from the bidirectional charger 110. Therefore, when the SMR 11 and SMR 12 that connect / disconnect the battery 10 and the PCU 20 are disconnected and no voltage is applied to the power lines PL and NL, the bidirectional charger 110 is not activated, so it is possible to suppress a voltage from being generated in an electric circuit including the PCU 20 due to a leakage current from the bidirectional charger 110.

[0066] When the bidirectional charger 110 is not activated, the bidirectional charger 110 is in an unstable state and may cause an unintended short circuit or malfunction due to noise, etc. According to the present embodiment, when the SMR 11 and the SMR 12 are in a connected state and the voltage (battery voltage) of the battery 10 is applied to the power lines PL and NL, the bidirectional charger 110 is activated. Therefore, when a voltage is applied to the power lines PL and NL, it is possible to prevent the bidirectional charger 110 from short circuiting or malfunctioning.

[0067] According to the present embodiment, in S10 in which the SMR 11 and SMR 12 are in an interrupted state and the bidirectional charger 110 and the bidirectional DCDC converter 130 are in a stopped state, an initialization process is performed, and an abnormality diagnosis process for the PCU 20 and the like and an offset correction process for the voltage sensor 91 and the current sensor 92 are performed. Therefore, the voltage of the battery 10 and the voltage caused by the leakage current of the bidirectional charger 110 are not applied to the power lines PL and NL, and even if an abnormality diagnosis process and an offset correction process are performed on the assumption that the voltage VL is 0 [V], erroneous detection and erroneous correction can be suppressed.

[0068] [Embodiment 2] In the above embodiment (embodiment 1), in the SMR connection process, when SMR 11 and SMR 12 are disconnected, the generation of a voltage in an electric circuit including PCU 20 due to a leakage current of bidirectional charger 110 is suppressed. In embodiment 2, in the SMR disconnection process, the generation of a voltage in an electric circuit including PCU 20 due to a leakage current of bidirectional charger 110 is suppressed. The configuration of electric vehicle V is the same as in embodiment 1.

[0069] 6 is a time chart for explaining the SMR disconnection process in the second embodiment. At time t3, SMR 11 and SMR 12 are in a connected state (ON), and battery 10 is connected to power lines PL and NL. Therefore, voltage VL is the voltage (battery voltage) of battery 10. In addition, the start-up signal of bidirectional charger 110 is ON, and bidirectional charger 110 is in a started-up state.

[0070] When the power switch 90 is operated to stop the vehicle system or when external charging of the battery 10 is terminated, the SMR disconnection process is started at time t4. When the SMR disconnection process is started at time t4, the SMR 12 is switched to a cut-off state (OFF). Also, at time t4, the bidirectional DC-DC converter 130 steps down the voltage remaining between the power line PL and the power line NL and supplies it to the auxiliary battery 140. This causes the voltage VL to drop over time. After a predetermined period has elapsed from time t4, the start-up signal of the bidirectional charger 110 changes from ON to OFF, the start-up switch 66 of the drive circuit 60 is turned off (cut-off), and the bidirectional charger 110 stops. The predetermined period is a period during which the voltage VL drops due to the operation of the bidirectional DC-DC converter 130, and the voltage VL becomes a voltage that does not cause failure or damage to each device even if the bidirectional charger 110 becomes in an unstable state and malfunctions due to unintended short circuits or noises occur, and is set in advance by experiments, etc.

[0071] When the voltage VL drops to approximately 0 [V] due to the operation of the bidirectional DC-DC converter 130, the SMR 11 is switched to the cutoff state (off) at time t5. The period from time t4 to time t5 is a period during which the voltage VL becomes approximately 0 [V] due to the operation of the bidirectional DC-DC converter 130, and is determined in advance by an experiment or the like.

[0072] 7 is a flowchart showing an outline of the SMR disconnection process executed by the control ECU 300. This flowchart is started when the power switch 90 is operated to stop the vehicle system and when external charging of the battery 10 is completed. Before the SMR disconnection process is started, the SMRs 11 and 12 are in a connected state (ON), and the bidirectional charger 110 is in an activated state.

[0073] When the vehicle system is stopped or when external charging is completed, first, in S20, the SMR 12 is switched from the connected state to the disconnected state, and the process proceeds to S21. In S21, the bidirectional DC-DC converter 130 is operated to step down the voltage remaining between the power lines PL and NL and to supply it to the auxiliary battery 140.

[0074] In the next S22, it is determined whether or not a third predetermined period has elapsed since the SMR 12 was switched to the cutoff state and the bidirectional DC-DC converter 130 was operated. The third predetermined period is a period during which the voltage VL becomes a voltage that will not cause failure or damage to each device even if the bidirectional charger 110 is in an undefined state and malfunctions due to unintended short circuits or noise occur. S22 is repeatedly processed until the third predetermined period has elapsed, and if the third predetermined period has elapsed, a positive determination is made and the process proceeds to S23.

[0075] In S23, the bidirectional charger 110 is stopped. The start switch 66 of the drive circuit 60 of the bidirectional charger 110 is turned off (shut off), thereby stopping the bidirectional charger 110.

[0076] In the next S24, it is determined whether or not a fourth predetermined period has elapsed since the SMR 12 was switched to the cutoff state and the bidirectional DC-DC converter 130 was operated. The fourth predetermined period is a period during which the voltage VL becomes approximately 0 [V]. S24 is repeatedly processed until the fourth predetermined period has elapsed, and when the fourth predetermined period has elapsed, a positive determination is made and the process proceeds to S25. Note that in S24, when it is detected from the output signal of the voltage sensor 91 that the voltage VL has become approximately 0 [V], a positive determination may be made and the process proceeds to S25.

[0077] In S25, the SMR 11 is switched to the cut-off state, and this routine ends. Note that following S25, assuming that the voltage VL is 0 [V], a diagnostic process is performed to determine whether or not an abnormality has occurred in the PCU 20, the bidirectional charger 110, the bidirectional DC-DC converter 130, etc., and an offset correction process (offset value learning process) for the voltage sensor 91 and the current sensor 92 is performed, and then this routine ends.

[0078] According to the second embodiment, the SMR disconnection process is started, and the voltage VL drops toward 0 [V] due to the operation of the bidirectional DC-DC converter 130, and the process is stopped when a voltage is applied to the power lines PL and NL. Before the bidirectional charger 110 is stopped, the bidirectional charger 110 is activated, and when there is a possibility of a leak current from the bidirectional charger 110, a voltage is applied to the power lines PL and NL, so that even if a leak current occurs from the bidirectional charger 110, it is possible to suppress a voltage rise in the electric circuit including the PCU 20 due to the leak current. In addition, when the SMR 11 and the SMR 12 are disconnected and no voltage is applied to the power lines PL and NL, the bidirectional charger 110 is stopped, so that it is possible to suppress a voltage from being generated in the electric circuit including the PCU 20 due to the leak current of the bidirectional charger 110.

[0079] When the bidirectional charger 110 is not activated, the bidirectional charger 110 is in an unstable state and may malfunction due to an unintended short circuit or noise. According to the second embodiment, when the SMR 11 and the SMR 12 are in a connected state and the voltage (battery voltage) of the battery 10 is applied to the power lines PL and NL, the bidirectional charger 110 is activated. Therefore, when a voltage is applied to the power lines PL and NL, it is possible to prevent the bidirectional charger 110 from being short circuited or malfunctioning.

[0080] In the second embodiment, SMR11 may be cut off (OFF) at time t4, and SMR12 may be cut off (OFF) at time t5. The reason why SMR11 and SMR12 are cut off at different timings is to ensure that SMR11 and SMR12 are cut off (to ensure that the cut-off states of SMR11 and SMR12 are detected). Also, SMR11 and SMR12 may be cut off (OFF) simultaneously at time t4.

[0081] [Variation 1] FIG. 8 is a diagram showing the configuration of an electric vehicle according to Modification 1. An electric vehicle Va according to Modification 1 differs from an electric vehicle V according to the above embodiment only in the configuration of a system main relay (SMR). In FIG. 8, the electric vehicle Va includes an SMR 13 in addition to SMR 11 and SMR 12. The SMR 13 is connected in parallel with the SMR 11, and connects / disconnects between the positive electrode of the battery 10 and the power line PL. A limiting resistor 14 is connected in series to the SMR 13. In Modification 1, the SMR 13 corresponds to the "first relay" of the present disclosure, the SMR 11 corresponds to the "second relay" of the present disclosure, and the SMR 12 corresponds to the "third relay" of the present disclosure.

[0082] 9 is a time chart for explaining the SMR connection process in the modified example 1. At time t7, SMR11, SMR12, and SMR13 are in a cutoff state (OFF), and the battery 10 is not connected to the power lines PL and NL. Therefore, the voltage VL is 0 [V]. In addition, the start-up signal of the bidirectional charger 110 is OFF, and the bidirectional charger 110 is in a stopped state.

[0083] When the power switch 90 is operated to start the vehicle system, or when the connector 80 of the EVSE 100 is connected to the inlet 70 to start charging the battery 10, the SMR connection process is started at time t8. When the SMR connection process is started at time t8, the SMR 12 and the SMR 13 are switched to a connected state (ON). Since the limiting resistor 14 is connected in series to the SMR 13, the current flowing through the power line PL is limited, and a pre-charge process is performed in which the voltage VL gradually increases. After a predetermined period has elapsed from time t7, the start-up signal of the bidirectional charger 110 changes from OFF to ON, the start-up switch 66 of the drive circuit 60 is turned ON (connected), and the bidirectional charger 110 starts up. The predetermined period is a period during which the voltage VL increases due to the pre-charge process and a voltage is reliably applied between the power line PL and the power line NL, and is set in advance by experiments or the like.

[0084] When the precharge time ends, at time t8, SMR 13 is switched to the disconnected state (OFF) and SMR 11 is switched to the connected state (ON). The precharge time may be determined in advance by experiment or the like so that the voltage VL increases due to the precharge and a large current does not flow through the contacts of the SMR when the SMR is connected.

[0085] In this first modification as well, when a voltage is applied to the power lines PL and NL in the SMR connection process (during the precharge process), the bidirectional charger 110 is started up, and therefore, the same effects as those of the first embodiment are achieved.

[0086] [Variation 2] In the above-mentioned second embodiment, from time t4 to time t5 (FIG. 6), the bidirectional DC-DC converter 130 steps down the voltage remaining between the power line PL and the power line NL and supplies it to the auxiliary battery 140 (FIG. 7: S21). However, when the SMR disconnection process starts at time t4, the SMR 12 may be switched to the cut-off state (off) and a discharge resistor (discharge circuit) and the inverter 22 provided in the PCU 20 may be operated so that the voltage VL decreases over time. According to this second modification, the same effect as the above-mentioned second embodiment can be achieved without operating the bidirectional DC-DC converter 130.

[0087] The electric vehicle V in the above embodiment uses the bidirectional charger 110 to convert AC power supplied from the EVSE 100 into DC power to charge the battery 10, and also converts the DC power of the battery 10 into AC power and outputs the AC power to the in-vehicle outlet 120. However, instead of the bidirectional charger 110, the electric vehicle may use a charger that does not have a function of outputting AC power to the in-vehicle outlet 120 (a charger that has only a function of charging the battery 10).

[0088] The electric vehicle V in the above embodiment uses the bidirectional charger 110 to convert AC power supplied from the EVSE 100 into DC power to charge the battery 10, and also converts the DC power of the battery 10 into AC power and outputs the AC power to the in-vehicle outlet 120. However, instead of the bidirectional charger 110, the electric vehicle may be equipped with a converter having a function of outputting AC power to the in-vehicle outlet 120 (a converter not having a function of charging the battery 10). In this case, the electric vehicle does not need to be equipped with the inlet 70.

[0089] In the above embodiment, an electric vehicle (BEV: Battery Electric Vehicle) has been used as the electric vehicle for explanation, but any vehicle equipped with an electricity storage device serving as a drive source, such as a plug-in hybrid electric vehicle (PHEV) or a hybrid electric vehicle (HEV), may be used. Furthermore, the SMR connection process of the first embodiment and the SMR disconnection process of the second embodiment may be executed in the electric vehicle V, and the SMR connection process of the first modification and the SMR disconnection process of the second modification may be executed in the electric vehicle Va, or each SMR connection process and each SMR disconnection process may be executed in an appropriate combination.

[0090] 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 by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0091] 10 battery, 11,12,13 SMR 14 limiting resistor, 20 PCU, 21 DC / DC converter, 22 inverter, 30 motor generator, 40 differential gear, 50 drive wheel, 60 drive circuit, 61 positive voltage power supply, 62 high side gate driver, 63 low side gate driver, 64 diode, 65 bootstrap capacitor, 66 start switch, 70 inlet, 80 connector, 90 power switch, 91 voltage sensor, 92 current sensor, 100 EVSE, 110 bidirectional charger, 111 inverter, 112 isolation circuit, 112a first coil, 112b second coil, 113 inverter, 113a first inverter, 113b second inverter, 115,116 relay, 120 vehicle outlet, 130 bidirectional DCDC converter, 140 auxiliary battery, 150 auxiliary, 200 External power supply, 300 control ECU, C1 smoothing capacitor, NL,PL power line, V,Va electric vehicle.

Claims

1. An electric vehicle comprising: a power storage device; an electric motor that drives drive wheels; a drive device that drives the electric motor using power from the power storage device; a relay that connects / disconnects the power storage device and the drive device; a converter that is connected to a power line between the relay and the drive device and converts AC power supplied from an external power source into DC power to charge the power storage device; and a control device, The control device starts the converter or stops the converter when a voltage is applied to the power line to which the converter is connected, The power supply system further includes an auxiliary battery that supplies power to an auxiliary device, and a bidirectional DC-DC converter that exchanges power between the auxiliary battery and the power line, The control device executes a disconnection process to switch the relay from a connected state to a disconnected state, the disconnection process includes a process of switching the relay from a connected state to a disconnected state, then using the bidirectional DC-DC converter to supply power from the power line to the auxiliary battery to reduce a voltage of the power line, and stopping the converter after a predetermined period of time has elapsed.

2. An electric vehicle comprising: a power storage device; an electric motor that drives drive wheels; a drive device that drives the electric motor using power from the power storage device; a relay that connects / disconnects the power storage device and the drive device; a converter that is connected to a power line between the relay and the drive device and that converts DC power from the power storage device into AC power and outputs the AC power to an outlet; and a control device, The control device starts the converter or stops the converter when a voltage is applied to the power line to which the converter is connected, The power supply system further includes an auxiliary battery that supplies power to an auxiliary device, and a bidirectional DC-DC converter that exchanges power between the auxiliary battery and the power line, The control device executes a disconnection process to switch the relay from a connected state to a disconnected state, the disconnection process includes a process of switching the relay from a connected state to a disconnected state, then using the bidirectional DC-DC converter to supply power from the power line to the auxiliary battery to reduce a voltage of the power line, and stopping the converter after a predetermined period of time has elapsed.

3. An electric vehicle comprising: a power storage device; an electric motor that drives drive wheels; a drive device that drives the electric motor using power from the power storage device; a relay that connects / disconnects the power storage device and the drive device; a converter that is connected to a power line between the relay and the drive device and converts AC power supplied from an external power source into DC power to charge the power storage device; and a control device, The converter is configured to convert DC power of the power storage device into AC power and output the AC power to an outlet, The control device starts the converter or stops the converter when a voltage is applied to the power line to which the converter is connected, The power supply system further includes an auxiliary battery that supplies power to an auxiliary device, and a bidirectional DC-DC converter that exchanges power between the auxiliary battery and the power line, The control device executes a disconnection process to switch the relay from a connected state to a disconnected state, the disconnection process includes a process of switching the relay from a connected state to a disconnected state, then using the bidirectional DC-DC converter to supply power from the power line to the auxiliary battery to reduce a voltage of the power line, and stopping the converter after a predetermined period of time has elapsed.

4. An electric vehicle comprising: a power storage device; an electric motor that drives drive wheels; a drive device that drives the electric motor using power from the power storage device; a relay that connects / disconnects the power storage device and the drive device; a converter that is connected to a power line between the relay and the drive device and converts AC power supplied from an external power source into DC power to charge the power storage device; and a control device, The control device executes a disconnection process to switch the relay from a connected state to a disconnected state, the disconnection process includes a process of switching a relay that connects / disconnects one pole of the power storage device and the drive device from a connected state to a disconnected state, and after a predetermined period of time has elapsed, switching a relay that connects / disconnects the other pole of the power storage device and the drive device from a connected state to a disconnected state, and stopping the converter during the predetermined period of time; The control device of the electric vehicle, when a voltage is applied to the power line to which the converter is connected, starts the converter or stops the converter.

5. An electric vehicle comprising: a power storage device; an electric motor that drives drive wheels; a drive device that drives the electric motor using power from the power storage device; a relay that connects / disconnects the power storage device and the drive device; a converter that is connected to a power line between the relay and the drive device and that converts DC power from the power storage device into AC power and outputs the AC power to an outlet; and a control device, The control device executes a disconnection process to switch the relay from a connected state to a disconnected state, the disconnection process includes a process of switching a relay that connects / disconnects one pole of the power storage device and the drive device from a connected state to a disconnected state, and after a predetermined period of time has elapsed, switching a relay that connects / disconnects the other pole of the power storage device and the drive device from a connected state to a disconnected state, and stopping the converter during the predetermined period of time; The control device of the electric vehicle, when a voltage is applied to the power line to which the converter is connected, starts the converter or stops the converter.

6. An electric vehicle comprising: a power storage device; an electric motor that drives drive wheels; a drive device that drives the electric motor using power from the power storage device; a relay that connects / disconnects the power storage device and the drive device; a converter that is connected to a power line between the relay and the drive device and converts AC power supplied from an external power source into DC power to charge the power storage device; and a control device, The converter is configured to convert DC power of the power storage device into AC power and output the AC power to an outlet, The control device executes a disconnection process to switch the relay from a connected state to a disconnected state, the disconnection process includes a process of switching a relay that connects / disconnects one pole of the power storage device and the drive device from a connected state to a disconnected state, and after a predetermined period of time has elapsed, switching a relay that connects / disconnects the other pole of the power storage device and the drive device from a connected state to a disconnected state, and stopping the converter during the predetermined period of time; The control device of the electric vehicle, when a voltage is applied to the power line to which the converter is connected, starts the converter or stops the converter.

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