Power Supply System

Abstract

To disclose a technology capable of suppressing an overcurrent that can be generated at circuit connection after termination of insulation diagnosis with a simple circuit.SOLUTION: A power supply system comprises: a converter; a smoothing capacitor connected between lines at the DC side of the converter; a connection cable connectable with a motor-driven mobile body that moves by a power; a switching unit that can open and close a circuit connecting between the DC side of the converter and the connection cable; and a control unit that controls the switching unit. The switching unit has: a first switch electrically and directly coupling between the DC side of the converter and the connection cable; and a second switch provided in parallel with the first switch and capable of connecting between the DC side of the converter and the connection cable via a predetermined resistor. The control unit executes: first processing of electrically connecting a circuit in the motor-driven mobile body and the connection cable with the motor-driven mobile body after insulation diagnosis, and then, closing the second switch; and second processing of closing the first switch in a state where the second switch is closed, and then, opening the second switch in a state where the first switch is closed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply system. [Background technology]

[0002] In recent years, various types of electrically powered moving bodies, such as electric automobiles, ships, and aircraft, that run on the power of electric motors, have become increasingly common. Accordingly, there has been active development of electrical equipment that controls the charging of onboard batteries (hereinafter sometimes referred to as "driving batteries" or "main batteries") that supply power to the driving electric motors (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-161816 Summary of the Invention [Problem to be solved by the invention]

[0004] When a connection cable for electrical equipment is connected to an electrically powered vehicle, an insulation diagnosis is sequentially performed to confirm that the connection is normal. During the insulation diagnosis, a predetermined voltage is applied to the connection cable to check for short circuits and ground faults. The voltage applied during the insulation diagnosis is usually higher than the voltage of electricity that flows through the connection cable after the insulation diagnosis is completed. Therefore, for example, if the electrical equipment is equipped with a smoothing capacitor, an overcurrent may occur when the circuit is connected after the insulation diagnosis is completed due to the potential difference between the voltage of the circuit of the electrically powered vehicle and the voltage of the smoothing capacitor of the electrical equipment.

[0005] One possible solution to this overcurrent problem is to execute a process to reduce the potential difference between the voltage of the circuit of the electrically powered vehicle and the voltage of the smoothing capacitor after completing the insulation diagnosis. However, this process leads to a complicated circuit configuration and sequence.

[0006] Therefore, the present application discloses a technique that makes it possible to suppress overcurrent that may occur when connecting a circuit after insulation diagnosis is completed, using a simple circuit. [Means for solving the problem]

[0007] In order to solve the above problem, in the present invention, once the insulation diagnosis is completed, the connection cable connected to the electric vehicle and the DC side of the converter are electrically connected via a specified resistor, and then electrically connected directly without going through a resistor.

[0008] In detail, the present invention is a power supply system comprising: a converter capable of outputting DC power; a smoothing capacitor connected between the lines on the DC side of the converter; a connection cable connectable to an electrically powered mobile body that moves using electric power; an opening / closing unit capable of opening and closing a circuit connecting the DC side of the converter and the connection cable; and a control unit that controls the opening / closing unit. The opening / closing unit has a first opening / closing unit that can electrically connect the DC side of the converter and the connection cable directly; and a second opening / closing unit that is arranged in parallel with the first opening / closing unit and can connect the DC side of the converter and the connection cable via a predetermined resistor. When an insulation diagnosis of the connection cable using the DC power output by the converter is completed, the control unit executes a first process of electrically connecting the circuit within the electrically powered mobile body to the connection cable and then closing the second opening / closing unit; and a second process of closing the first opening / closing unit with the second opening / closing unit closed, and then opening the second opening / closing unit with the first opening / closing unit closed.

[0009] Here, the electric vehicle refers to an electric vehicle, such as an electric standard car, a large Examples of such vehicles include automobiles, motorcycles, ships, aircraft, and various other moving objects. Furthermore, "electrically directly connectable" refers to a state in which the converter is connected without going through a resistor, and does not refer to a state in which the converter and the connecting cable components are in physical contact with each other. Furthermore, "connectable via a specified resistor" refers to a state in which the converter is electrically connected via a specified resistor, and does not refer to a state in which the converter and the connecting cable components are in physical contact with the specified resistor.

[0010] In the above power supply system, after completing the insulation diagnosis, when closing the switch after electrically connecting the circuit in the electric vehicle to the connection cable, the second switch is closed first and then the first switch is closed. Then, the first switch is closed first and then the second switch is opened. Therefore, a transient overcurrent that may occur when closing the switch after completing the insulation diagnosis due to the charge remaining in the smoothing capacitor due to the insulation diagnosis is suppressed by the conduction of current through the specified resistor when the second switch is closed. Therefore, in the above power supply system, overcurrent suppression can be achieved by such opening and closing operations of the first switch and second switch, and it can be said that overcurrent suppression can be achieved with a relatively simple sequence and circuit configuration.

[0011] The predetermined resistor may have a resistance value such that, when the control unit executes the first process while the circuit in the electric vehicle is at a predetermined lower limit voltage, the magnitude of the current flowing through the predetermined resistor due to the potential difference between the circuit in the electric vehicle and the converter falls within the range of specifications defined for the electrical equipment for the electric vehicle. This makes it possible to minimize the possibility that a transient overcurrent caused by residual charge in the smoothing capacitor will occur, exceeding the range of specifications defined for the electrical equipment for the electric vehicle.

[0012] Furthermore, when the insulation diagnosis is completed in the first process, the control unit may close the second switch after confirming that the connection cable has a predetermined DC voltage with the circuit in the electric vehicle and the connection cable electrically connected to the electric vehicle. This makes it possible to minimize the possibility of an unexpected current occurring between the circuit in the electric vehicle and the converter when the switch unit is closed.

[0013] Furthermore, in the second process, the control unit may close the first switch after a predetermined time has elapsed since closing the second switch. Here, the predetermined time is a preset value, such as the time required for a transient overcurrent component caused by charge remaining in the smoothing capacitor due to insulation diagnosis to disappear due to attenuation in the predetermined resistor. This makes it possible to attenuate the overcurrent as much as possible using the predetermined resistor between the time the second switch is closed and the time the first switch is closed.

[0014] The converter may also convert power supplied from a power grid and output DC power, thereby making it possible to supply power from the power grid to circuits within the electrically powered vehicle. [Effects of the Invention]

[0015] According to the present invention, it is possible to suppress overcurrent that may occur when the circuit is connected after the insulation diagnosis is completed, using a simple circuit. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing an overview of the electrical behavior achieved by the EV connection unit disclosed in this application. [Figure 2] FIG. 2 is a diagram illustrating an example of an electrical facility using the EV connection unit according to the embodiment. [Figure 3] FIG. 3 shows the internal electrical configuration of the EV and the EV connection unit. [Figure 4] FIG. 4 is a diagram showing an example of an operation flow implemented in the EV connection unit according to the embodiment. [Figure 5] FIG. 5 is a diagram showing the electrical internal configuration of an EV connection unit according to a comparative example. [Figure 6] FIG. 6 is a diagram showing an example of an operation flow implemented in an EV connection unit according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Application example> FIG. 1 is a diagram showing an outline of the electrical behavior realized by an EV (Electric Vehicle) connection unit (an example of the "power supply system" referred to in the present application) disclosed in the present application. The EV connection unit is compatible with various types of electric vehicles (hereinafter referred to as "EVs"), including BEVs (Battery Electric Vehicles) that run on battery power alone, PHVs (Plug-in Hybrid Vehicles) that use both a battery and an internal combustion engine, FCVs (Fuel Cell Vehicles) that run on fuel cell power, and other electric vehicles. In the following explanation, we will use the example of connecting the EV connection unit to an EV that runs on power from an onboard battery, but if the EV connection unit is connected to an EV that runs on power from an onboard generator such as a fuel cell, it will receive power generated by the EV.

[0018] The EV connection unit is equipped with a converter that automatically adjusts the duty ratio so that the circuit connecting the EV and EV connection unit has an appropriate voltage, a smoothing capacitor to smooth the voltage of that circuit, and a switch that opens and closes the circuit connecting the converter to the connection cable connected to the EV.The EV also has an onboard battery and a switch that opens and closes the circuit connecting the onboard battery to the connection cable of the EV connection unit.The EV connection unit charges and discharges the onboard battery (charging the onboard battery and supplying power from the onboard battery) by appropriately adjusting the duty ratio of the EV connection unit, the switches on the EV, and the converter.

[0019] Various charging standards exist for electrical equipment to which EVs are connected, such as CHAdeMO (registered trademark). These charging standards stipulate various matters, such as methods for diagnosing the connection status of the connection cable and upper current limits, to ensure user safety and equipment maintenance. Therefore, in the EV connection unit shown in FIG. 1, when the connection cable is connected to an EV, an insulation diagnosis is performed in which a specified voltage is applied to the connection cable with the EV's switch open. If the insulation diagnosis confirms that the equipment is normal, the EV's switch is closed and charging or discharging of the battery is initiated.

[0020] When a specified voltage is applied to the connection cable during an insulation diagnosis, residual charge in the smoothing capacitor causes a potential difference equivalent to the specified voltage to remain in the circuit connecting the converter and the EV even after the insulation diagnosis is completed. For this reason, the EV connection unit disclosed herein includes a first switch that electrically connects the DC side of the converter directly to the connection cable, as shown in Figure 1, and a second switch in parallel that connects the DC side of the converter to the connection cable via a specified resistor. In this EV connection unit, before electrically connecting the DC side of the converter to the connection cable directly with the first switch, the second switch connects the DC side of the converter to the connection cable via a specified resistor. This resistor limits the magnitude of the current generated in the circuit due to the potential difference between the smoothing capacitor and the onboard battery to within the specified range of the charging standard. The change in the arrow in Figure 1 from solid to dashed represents an example of how the current magnitude is limited by the resistor.

[0021] <Embodiment> Hereinafter, embodiments will be described with reference to the drawings. The above is merely an embodiment and does not limit the technical scope of the present application.

[0022] FIG. 2 is a diagram showing an example of an electrical facility using an EV connection unit according to an embodiment. As shown in FIG. 2, the electrical facility 1 is connected to a power grid P. The electrical facility 1 may be installed in a house 2 as shown in FIG. 2, or may be installed in an apartment building, a commercial facility, or any other facility. The electrical facility 1 includes a distribution board 3, an EVPS (Electric Vehicle Power Station) 4, and a power grid P. System), PV-PCS5 (Photovoltaic - Power Conditioning System), Domestic Load 6. EVPS4 is an electrical device that connects to EV7.

[0023] The distribution board 3 is an electrical equipment that incorporates a main circuit breaker that opens and closes the circuit connecting the electrical equipment in the house 2 to the power grid P, circuit breakers that open and close the circuits of the wiring that branch off from the distribution board 3 to various parts of the house 2, and bus bars that connect the main circuit breaker and circuit breakers. The EVPS 4, PV-PCS 5, and domestic loads 6 of the house 2 are electrically connected through the distribution board 3. The EVPS 4, PV-PCS 5, and domestic loads 6 of the house 2 are also electrically connected to the power grid P through the distribution board 3.

[0024] The EVPS 4 is an electrical device that charges or discharges the onboard battery installed in the EV 7. The EVPS 4 includes an EV connection unit 9 with a connection cable 8 connectable to the EV 7, and an inverter unit 10 that converts electricity from AC to DC or DC to AC (AC-DC conversion). The EV connection unit 9 operates according to the amount of electricity stored in the EV 7. The inverter unit 10 maintains the DC voltage of the circuit connected to the EV connection unit 9 at a predetermined control target value. Therefore, for example, when the EV connection unit 9 operates to charge the EV 7, the inverter unit 10 operates to prevent the DC voltage of the circuit connected to the EV connection unit 9 from falling below the predetermined control target value, resulting in power flowing from the inverter unit 10 to the EV connection unit 9. Similarly, when the EV connection unit 9 operates to discharge the EV 7, the inverter unit 10 operates to prevent the DC voltage of the circuit connected to the EV connection unit 9 from exceeding the predetermined control target value, resulting in power flowing from the EV connection unit 9 to the inverter unit 10. The power that flows from the EV connection unit 9 to the inverter unit 10 passes through the distribution board 3 and is consumed by the home loads 6 or transmitted to the power grid P (sold).

[0025] The PV-PCS 5 is an electrical equipment that generates electricity using solar power generation panels installed on the roof of the house 2 or on the premises. The PV-PCS 5 converts DC power generated by the solar power generation panels into AC power. If the EVPS 4 is also compatible with solar power generation and has a PV unit for connecting solar power generation panels, the electrical equipment 1 may be configured such that the solar power generation panels are connected to the EVPS 4 without the PV-PCS 5. The electrical equipment 1 may also be configured to include equipment that generates electricity using an energy source other than solar power, such as a fuel cell. The electrical equipment 1 may also be configured such that the power generation equipment is omitted, or may be configured such that a stationary storage battery is also provided.

[0026] The domestic loads 6 are various electrical devices installed in the residence 2. Examples of the domestic loads 6 connected to the distribution board 3 include lighting installed in the residence 2, wiring outlets (receptacles) installed on walls or the like within the residence 2, ventilation equipment, and various other electrical devices. The domestic loads 6 may receive power supply not only from the power grid P, but also from the EVPS 4 or the PV-PCS 5 depending on the amount of solar radiation and the amount of power stored in the EVs 7.

[0027] 3 is a diagram showing the electrical internal configuration of the EV 7 and the EV connection unit 9. The EV 7 and the EV connection unit 9 will be described in detail below with reference to FIG.

[0028] As shown in Figure 3, the EV7 consists of the main battery MV, the EV relay VS, and the inlet IL. The EV7 has a control device VC. The main battery MV is an on-board battery that supplies power to the electric motor used for driving the EV7. Examples of the main battery MV include lithium-ion batteries, all-solid-state batteries, and various other secondary batteries. The inlet IL is a terminal for connecting and disconnecting the connection cable 8, and is configured to mate with the plug CN attached to the end of the connection cable 8. The inlet IL is located on the exterior of the EV7 to allow the user to easily connect and disconnect the plug CN, and is equipped with an electromagnetic locking mechanism to prevent accidental connection and disconnection of the plug CN. The EV relay VS is an electromagnetic contactor that can open and close the circuit connecting the inlet IL and the main battery MV, and opens and closes in response to control signals from the control device VC. The control device VC communicates with the EVPS4 via a control line LC to perform various controls, such as opening and closing the EV relay VS.

[0029] As shown in Fig. 3, the EV connection unit 9 includes a converter DC connected to the inverter unit 10, power lines LH and LL connecting the converter DC and the connection cable 8, a switch SS provided midway along the power line LH, a smoothing capacitor HC connected between the power lines LH and LL, and a control device CC that controls the converter DC and the switch SS. Note that Fig. 3 illustrates the EV connection unit 9 integrated with the inverter unit 10 within the EVPS 4, but the EV connection unit 9 may be separate from the housing of the inverter unit 10. Also, Fig. 3 illustrates the connection cable 8 as being inseparably connected to the housing of the EVPS 4, but the connection cable 8 may be detachable from the EVPS 4 using tools or the like to allow for maintenance work such as part replacement.

[0030] Converter DC automatically adjusts the duty cycle so that the power lines LH and LL connected to the EV 7 maintain an appropriate voltage. In this embodiment, because the EVPS 4 is configured to not only charge but also charge and discharge the EV 7, converter DC is an isolated bidirectional DC / DC converter. However, if the EVPS 4 is configured to only charge, converter DC may be a unidirectional converter that flows power in one direction from inverter unit 10 to the EV 7.

[0031] The smoothing capacitor HC is a capacitor that smoothes the voltage of the DC power that the converter DC outputs to the power lines LH and LL. The smoothing capacitor HC has an appropriate capacitance selected according to the power flowing through the EVPS 4.

[0032] The switchgear unit SS has a DC relay DS and a surge relay TS for opening and closing the power line LH connecting the converter DC and the connection cable 8, and a resistor TR connected in series with the surge relay TS. As shown in FIG. 3 , the switchgear unit SS has a parallel circuit of the surge relay TS and the resistor TR connected in series with the DC relay DS. Therefore, the switchgear unit SS can use either the DC relay DS or the surge relay TS to open or close the power line LH connecting the converter DC and the connection cable 8. When the DC relay DS is closed in the switchgear unit SS, the connection cable 8 is electrically connected directly to the DC side of the converter DC. When the surge relay TS is closed in the switchgear unit SS, the connection cable 8 is connected to the DC side of the converter DC via the resistor TR.

[0033] The resistor TR is used to prevent inrush current. The resistor TR has a resistance value that ensures that the magnitude of the current generated in the power line LH due to the potential difference between the smoothing capacitor HC and the main battery MV falls within the specifications required for the EVPS4 in the EV7 charger standard. The resistor TR may be a single resistor that satisfies a predetermined resistance value and rated power, or multiple resistors may be connected in parallel or series to meet the predetermined resistance value and rated power. For example, if a resistor has a resistance value of 11 Ω and a rated power of approximately 10 W, it is expected that the resistor TR will be formed using approximately four or five resistors.

[0034] The control device CC communicates with EV7 via the control line LC to perform various controls such as opening and closing the switching section SS and operating the converter DC. The control device CC is a device that realizes various controls by executing computer programs loaded in memory, and is equipped with an input / output interface for various input operations and information display.

[0035] An example of the operational flow implemented in the EV connection unit 9 will be described below. FIG. 4 is a diagram showing an example of the operational flow implemented in the EV connection unit 9 according to this embodiment. When a user of an EV 7 parks the EV 7 near the EVPS 4 and connects the connection cable 8 to the EV 7, an insulation diagnosis is performed to confirm that there are no abnormalities, and then the EVPS 4 and EV 7 are electrically connected. In other words, the EV connection unit 9 implements the following operational flow. The operational flow shown below is implemented mainly by the control of the control device CC.

[0036] (Step S1) The control device CC detects through communication via the control line LC that the connection cable 8 has been connected to the EV 7, and upon receiving various information related to charging and discharging (such as the state of the main battery MV) from the control device VC of the EV 7, closes the DC relay DS. At this time, the surge protection relay TS and the EV relay VS are open. Therefore, when the DC relay DS is closed, the power line LH is electrically connected to the EV relay VS of the EV 7.

[0037] (Step S2) Next, the control device CC temporarily operates the converter DC to gradually increase the potential difference between the power lines LH and LL. The control device CC then monitors the insulation resistance value between the power lines LH and LL until the potential difference between the power lines LH and LL reaches a specified test voltage (e.g., 450 V). Even if the potential difference between the power lines LH and LL reaches the specified test voltage, if the insulation resistance value between the power lines LH and LL is equal to or greater than a specified reference value, the control device CC issues a diagnostic result that there is no abnormality in the insulation. On the other hand, if the insulation resistance value between the power lines LH and LL falls below the specified reference value when the potential difference between the power lines LH and LL is equal to or less than the specified test voltage, the control device CC issues a diagnostic result that there is an abnormality in the insulation, stops the series of processes, and notifies the user of the abnormality in the insulation.

[0038] (Step S3) If the control device CC confirms in the process of step S2 that there is no abnormality in the insulation, it then opens the DC relay DS. At this time, the converter DC has already stopped, but a potential difference of the same magnitude as the test voltage remains between the part of the power line LH on the converter DC side of the DC relay DS and the power line LL due to the residual charge stored in the smoothing capacitor HC in step S2.

[0039] (Step S4) After opening the DC relay DS in the process of step S3, the control device CC sends a control signal to the control device VC to cause the control device VC to close the EV relay VS. As a result, the main battery MV of the EV 7 is electrically connected to the connection cable 8.

[0040] (Step S5) After causing control device VC to close EV relay VS in the processing of step S4, control device CC checks whether the voltage of connection cable 8, i.e., the potential difference between the power line LL and the portion of power line LH on the EV7 side of switch SS, is equal to or greater than a specified value (this is an example of the "predetermined lower limit voltage" herein, such as 50 V as specified by the EV7 charger standard). If the voltage of connection cable 8 does not reach or exceed the specified value, it may be due to an abnormality in EV relay VS or main battery MV, for example.

[0041] (Step S6) If the determination in step S5 is affirmative, the control device CC turns on the surge protection relay TS. When the surge protection relay TS is turned on, the converter DC and the main battery The battery MV is electrically connected to the power line LH via resistor TR. As described above, a potential difference equivalent to the test voltage remains due to the residual charge stored in the smoothing capacitor HC in step S2. When the surge relay TS is closed, a current caused by this potential difference is generated in the power line LH. However, resistor TR has a resistance value that ensures that the magnitude of the current generated in the power line LH due to this potential difference falls within the range required for the EVPS4 in the EV7 charger standard. Therefore, resistor TR ensures that the magnitude of the current generated in the power line LH due to this potential difference falls within the range required for the EVPS4. Therefore, there is no possibility of an overcurrent outside the allowable range flowing through the EV7's main battery MV, EV relay VS, etc.

[0042] (Step S7) The control device CC determines whether a specified waiting time has elapsed since the surge relay TS was closed. This waiting time is a value preset in the control device CC, and is, for example, the time required for the transient overcurrent component, which is caused by the charge remaining in the smoothing capacitor HC due to the insulation diagnosis, of the current flowing through the power line LH when the surge relay TS is closed, to disappear due to attenuation in the resistor TR.

[0043] (Step S8) If the determination in step S7 is affirmative, the control device CC closes the DC relay DS and then opens the surge relay TS. This removes the resistor TR from the current path in the power line LH, and the converter DC and the main battery MV are directly connected without passing through the resistor TR. Therefore, when electricity flows through the power line LH, no electrical loss occurs in the resistor TR.

[0044] The above is an example of the operational flow realized in the EV connection unit 9. After the above series of operational flows are performed, charging of the main battery MV from the EV connection unit 9 and power supply from the main battery MV to the household loads 6 and the like via the EV connection unit 9 are performed as appropriate.

[0045] With the EV connection unit 9 according to the above embodiment, the transient effect of closing the switching unit SS, which is caused by the charge remaining in the smoothing capacitor HC due to the insulation diagnosis, can be eliminated with a relatively simple sequence and circuit configuration: after closing the surge relay TS, the DC relay DS is closed a certain time later, and then the surge relay TS is opened. The effects of the EV connection unit 9 according to the above embodiment will be explained below using a comparative example.

[0046] <Comparative Example> A comparative example will be described below with reference to the drawings.

[0047] 5 is a diagram showing the electrical internal configuration of an EV connection unit according to a comparative example. The EV connection unit 109 according to the comparative example has additional components added to the EV connection unit 9 of the above embodiment. Therefore, components equivalent to those of the EV connection unit 9 of the above embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0048] As shown in FIG. 5 , the EV connection unit 109 has a configuration in which a resistor HR and a discharge relay HS are added to the EV connection unit 9. The discharge relay HS can open and close the circuit connecting the power line LH and the power line LL, and operates in response to a control signal from the control device CC. The resistor HR is connected in series with the discharge relay HS in the circuit connecting the power line LH and the power line LL. Therefore, when the discharge relay HS is closed, the power line LH and the power line LL are electrically connected via the resistor HR. The EVPS 104 has a device configuration including this EV connection unit 109 and the inverter unit 10.

[0049] Resistor HR and discharge relay HS are used to check the insulation quality and remove residual voltage from smoothing capacitor HC. The resistor HR is installed for the purpose of discharging the charge after the insulation diagnosis is completed. Therefore, the resistor HR is required to have the ability to discharge the charge within a specified time. Such a resistor HR may be a single resistor with a predetermined resistance value and rated power, or multiple resistors connected in parallel or series to achieve the predetermined resistance value and rated power. For example, if a resistor has a resistance value of 11 Ω and a rated power of about 10 W, it is expected that about four to five of them will be used to form the resistor HR. In the case of a cement resistor with such electrical characteristics, a single resistor will have dimensions of about 10 to several tens of mm, so using about four or five of them will require a considerable amount of space.

[0050] The EV connection unit 109 according to this comparative example implements the following operational flow. Figure 6 is a diagram showing an example of the operational flow implemented in the EV connection unit 109 according to the comparative example. When a user of EV 7 parks EV 7 near EVPS 104 and connects connection cable 8 to EV 7, the EV connection unit 109 implements the following operational flow.

[0051] When the connection cable 8 is connected to the EV 7, the control device CC closes the DC relay DS in the same manner as in step S1 above (S101). Then, the control device CC performs an insulation diagnosis in the same manner as in step S2 above (S102). Then, if the control device CC confirms in the processing of step S102 that there is no abnormality in the insulation, it opens the DC relay DS in the same manner as in step S3 above (S103). At this time, a potential difference of approximately the same magnitude as the test voltage remains between the part of the power line LH on the converter DC side of the DC relay DS and the power line LL due to the residual charge that was stored in the smoothing capacitor HC in step S102.

[0052] Next, the control device CC closes the discharge relay HS (S104). This electrically connects the power lines LH and LL via the resistor HR. Therefore, the residual charge stored in the smoothing capacitor HC in step S102 is converted into thermal energy in the resistor HR and discharged. As a result, the potential difference between the power lines LH and LL is reduced.

[0053] Next, the control device CC determines whether the voltage of the smoothing capacitor HC is equal to or less than a specified value based on the potential difference between the power lines LH and LL (S105). If the determination in step S105 is affirmative, the control device CC then opens the discharge relay HS (S106). This reduces the potential difference between the voltage of the main battery MV and the voltage of the smoothing capacitor HC compared to immediately after the insulation diagnosis is completed.

[0054] Next, similar to step S4, the control device CC sends a control signal to the control device VC to cause the control device VC to close the EV relay VS. This electrically connects the main battery MV of the EV 7 to the connection cable 8 (S107). Then, similar to step S5, the control device CC checks whether the voltage of the connection cable 8 is equal to or higher than the specified voltage (S108).

[0055] If the control device CC makes a positive determination in step S108, it closes the inrush relay TS (S109). Then, the control device CC determines whether a specified waiting time has elapsed since the inrush relay TS was closed (S110). If the control device CC makes a positive determination in the processing of step S110, it closes the DC relay DS and then opens the inrush relay TS. This removes the resistor TR from the current path in the power line LH. Therefore, no electrical loss occurs in the resistor TR when electricity flows through the power line LH.

[0056] An example of the operation flow realized by the EV connection unit 109 has been described above. After the above series of operational flows are performed, charging of the main battery MV from the EV connection unit 109 and power supply from the main battery MV to the household loads 6 and the like via the EV connection unit 109 are performed as appropriate.

[0057] Like the EV connection unit 9 of the embodiment, the EV connection unit 109 of this comparative example can also eliminate the effects of residual charge in the smoothing capacitor HC through insulation diagnosis. However, in this comparative example, a process is performed to discharge the residual charge in the smoothing capacitor HC after the insulation diagnosis is completed, and as is clear from a comparison of Figures 3 and 5, or Figures 4 and 6, the series of sequences and circuit configuration are more complex than those of the EV connection unit 9 of the embodiment. Therefore, it can be said that the circuit configuration and sequence can be made relatively simpler in the EV connection unit 9 of the embodiment than in the EV connection unit 109 of this comparative example.

[0058] <Modification> In the above embodiment, the determination in step S7 is based on a specified standby time. However, the determination may be based on, for example, the current flowing through the power line LH. In the above embodiment, the control device CC controls each component of the EV connection unit 9. However, for example, the control device CC may control the entire EVPS 4. The EVPS 4 may charge and discharge the EV 7 in response to commands from a higher-level device that monitors and controls all electrical equipment installed in the residence 2. In the above embodiment, the electrical equipment 1 receives power from a power grid P established by an electric power company or the like. However, the electrical equipment 1 may be separated from the power grid P and may be independent of the power grid P, such as by a private power generation facility installed in the residence 2. The EV connection unit 9 may also be used to charge and discharge various electrically-powered mobile objects other than vehicles, or to supply power from various electrically-powered mobile objects. The above embodiment may also be modified as appropriate.

[0059] The present application includes the following additional matters. <Appendix 1> A converter (DC) capable of outputting direct current power, A smoothing capacitor (HC) connected between the DC side lines of the converter, a connection cable (8) connectable to an electrically powered mobile body; a switch (SS) capable of opening and closing a circuit connecting the DC side of the converter and the connection cable; a control unit (CC) that controls the opening / closing unit, The opening and closing section is a first switch (DS) capable of electrically connecting the DC side of the converter and the connection cable directly; a second switch (TS) that is provided in parallel with the first switch and that can connect the DC side of the converter and the connection cable via a predetermined resistor (TR), The control unit a first process (S6) of electrically connecting a circuit in the electric vehicle to the connection cable and then closing the second switch when the insulation diagnosis of the connection cable using the DC power output by the converter is completed; and executing a second process (S8) of closing the first switch while keeping the second switch closed, and then opening the second switch while keeping the first switch closed. Power supply system. [Explanation of symbols]

[0060] P··Power system 1. Electrical equipment 2. Housing 3. Distribution board 4. EVPS 5··PV-PCS 6. In-house load 7 EV 8. Connection cable 9. EV connection unit 10. Inverter unit LC··Control line LH··Power line LL··Power line CC··Control device SS··Opening and Closing Section DS DC Relay TS··Surge Protection Relay TR··Resistor HC smoothing capacitor DC Converter CN plug MV··Main battery VS··EV Relay VC control device HS··Discharge relay HR...Resistor IL Inlet 104··EVPS 109··EV connection unit

Claims

1. a converter capable of outputting DC power; A smoothing capacitor connected between the lines on the DC side of the converter; a connection cable connectable to an electrically powered mobile body; an opening / closing unit that opens and closes a circuit that connects the DC side of the converter and the connection cable; a control unit that controls the opening and closing unit, The opening and closing section is a first switch capable of electrically connecting the DC side of the converter and the connection cable directly; a second switch that is provided in parallel with the first switch and that can connect the DC side of the converter and the connection cable via a predetermined resistor, The control unit a first process of electrically connecting a circuit in the electric vehicle to the connection cable and then closing the second switch when an insulation diagnosis of the connection cable using the DC power output by the converter is completed; a second process of closing the first switch while keeping the second switch closed, and then opening the second switch while keeping the first switch closed; Power supply system.

2. the predetermined resistor has a resistance value such that, when the control unit executes the first process in a state where the circuit in the electric vehicle is at a predetermined lower limit voltage, the magnitude of the current flowing through the predetermined resistor due to the potential difference between the circuit in the electric vehicle and the converter falls within a range of specifications defined for the electrical equipment for the electric vehicle. The power supply system according to claim 1 .

3. When the insulation diagnosis is completed in the first process, the control unit confirms that the connection cable has a predetermined DC voltage in a state where the circuit in the electric vehicle and the connection cable are electrically connected to the electric vehicle, and then closes the second switch. The power supply system according to claim 1 or 2.

4. the control unit, in the second process, closes the first switch after a predetermined time has elapsed since closing the second switch; The power supply system according to any one of claims 1 to 3.

5. the converter converts power supplied from a power grid and outputs DC power; The power supply system according to any one of claims 1 to 4.

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