Inrush current prevention circuit and charging / discharging device for electric vehicles

Abstract

To provide a rush current prevention circuit that can correctly determine timeout regardless of whether a rush current prevention function is installed in a motor car.SOLUTION: A rush current prevention circuit 10 comprises: a first voltmeter 12 that measures a voltage value V1 of a voltage input to one ends of variable resistances R, RL1, RL2; a second voltmeter 13 that measures a voltage value V2 of a voltage output from the other ends of the variable resistances R, RL1, RL2; and a control unit 14 that controls resistance values of the variable resistances R, RL1, RL2 based on the voltage values V1, V2. During a period from when the voltage value V1 starts increasing until when the voltage value V2 matches the voltage value V1, the control unit 14 increases the resistance values of the variable resistances R, RL1, RL2. When the voltage value V2 does not match the voltage value V1 during a period from when the voltage value V1 starts increasing until a timeout period corresponding to the gradient of the increase elapses, the control unit 14 performs predetermined timeout processing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inrush current prevention circuit that prevents inrush current from an electric vehicle and a charging / discharging device for an electric vehicle. [Background technology]

[0002] With the recent spread of electric vehicles (EVs, Electric Vehicles) and plug-in hybrid vehicles (PHVs, Plug-in Hybrid Vehicles), there has been an increase in the number of cases where charging and discharging devices for electric vehicles, known as V2H (Vehicle to Home), are installed in homes.

[0003] As shown in FIG. 3, a conventional general charging / discharging device 100 for an electric vehicle includes a connector 107 connected to an inlet 22 of an electric vehicle 20A, an inrush current prevention circuit 101 that prevents an inrush current from flowing from a battery 21 mounted on the electric vehicle 20A through the connector 107 when discharging of the battery 21 begins, a relatively large-capacity capacitor 105, and a DC / AC conversion circuit 106.

[0004] The inrush current prevention circuit 101 includes a variable resistor composed of a first relay RL1, a second relay RL2, and a resistor R, a first voltmeter 102 that measures a voltage value V1 of a voltage input to one end of the variable resistor (i.e., the voltage of the first power line L1 connected to the connector 107), a second voltmeter 103 that measures a voltage value V2 of a voltage output from the other end of the variable resistor (i.e., the voltage of the second power line L2 connected to the capacitor 105 and the DC / AC conversion circuit 106), and a control unit 104 that controls the resistance value of the variable resistor (i.e., the opening and closing of the first relay RL1 and the second relay RL2) based on these two voltage values ​​V1 and V2.

[0005] When the control unit 104 detects that the contactor C in the electric vehicle 20A has been closed (i.e., that the battery 21 has started to discharge) based on an increase in the voltage value V1, it closes the first relay RL1 and opens the second relay RL2 (see FIG. 4). As a result, the current flowing from the battery 21 is limited by the resistor R, and the capacitor 105 is precharged relatively slowly.

[0006] When the control unit 104 detects that the pre-charging is completed based on the fact that the voltage value V2 matches the voltage value V1, it returns the first relay RL1 to the open state and returns the second relay RL2 to the closed state (see FIG. 4). As a result, from this point on, current flows from the battery 21 to the capacitor 105 and the DC / AC conversion circuit 106 without passing through the resistor R.

[0007] Furthermore, if the voltage value V2 does not match the voltage value V1 within a predetermined timeout period Δt after detecting the start of discharge of the battery 21, the control unit 104 performs timeout processing (see FIG. 4). The timeout processing includes, for example, stopping the discharge by returning the contactor C to the open state and notifying the user of an abnormality.

[0008] The use of a variable resistor to prevent inrush current is described, for example, in Patent Document 1. Also, providing a timeout period for precharging is described, for example, in Patent Document 2. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-099184 [Patent Document 2] Japanese Patent Application Publication No. 2019-092341 Summary of the Invention [Problem to be solved by the invention]

[0010] However, when this conventional electric vehicle charging / discharging device 100 is connected to an electric vehicle 20B (see FIG. 5) equipped with a DC / DC conversion circuit 23 having an inrush current prevention function, the conventional electric vehicle charging / discharging device 100 may erroneously determine a timeout.

[0011] That is, when connected to an electric vehicle 20B equipped with an inrush current prevention function, as shown in FIG. 6, the voltage value V1 rises slowly when discharge begins, and the rise in voltage value V2 is therefore very slow. As a result, even if no particular abnormality occurs, precharging may not be completed within the timeout period Δt.

[0012] The present invention has been made in consideration of the above circumstances, and has an object to provide an inrush current prevention circuit and an electric vehicle charging / discharging device that can correctly determine a timeout regardless of whether the electric vehicle is equipped with an inrush current prevention function. [Means for solving the problem]

[0013] In order to solve the above problem, the inrush current prevention circuit of the present invention includes a variable resistor, a first voltmeter that measures a voltage value V1 of a voltage input to one end of the variable resistor, a second voltmeter that measures a voltage value V2 of a voltage output from the other end of the variable resistor, and a control unit that controls the resistance value of the variable resistor based on the voltage values ​​V1 and V2, wherein the control unit increases the resistance value of the variable resistor from the time when the voltage value V1 starts to rise until the voltage value V2 matches the voltage value V1, and the control unit performs a predetermined timeout process if the voltage value V2 does not match the voltage value V1 from the time when the voltage value V1 starts to rise until a timeout period corresponding to the slope of the rise has elapsed.

[0014] In this configuration, instead of a uniform timeout period, timeout processing is performed if voltage value V2 does not match voltage value V1 within a timeout period corresponding to the slope of the increase in voltage value V1. Therefore, with this configuration, by lengthening the timeout period when the increase in voltage value V1 is gradual, it is possible to avoid erroneous timeout determination.

[0015] The control unit of the inrush current prevention circuit can, for example, set the timeout period to Δt when the slope of the increase in voltage value V1 is greater than a predetermined threshold, and can set the timeout period to Δt', which is longer than Δt, when the slope of the increase in voltage value V1 is smaller than the predetermined threshold.

[0016] The variable resistor of the inrush current prevention circuit can have a configuration including, for example, a first relay and a fixed resistor that form a series circuit, and a second relay connected in parallel to the series circuit. In this case, the control unit can increase the resistance value of the variable resistor by closing the first relay and opening the second relay, and can restore the resistance value of the variable resistor to its original value by opening the first relay and closing the second relay.

[0017] In addition, in order to solve the above-mentioned problems, the charging / discharging device for an electric vehicle according to the present invention includes a variable resistor, a connector for connecting to an electric vehicle and connected to one end of the variable resistor, a capacitor and a DC / AC conversion unit connected to the other end of the variable resistor, a first voltmeter that measures a voltage value V1 of a voltage input to one end of the variable resistor, a second voltmeter that measures a voltage value V2 of a voltage output from the other end of the variable resistor, and a control unit that controls the resistance value of the variable resistor based on the voltage values ​​V1 and V2, wherein the control unit increases the resistance value of the variable resistor from when the voltage value V1 starts to rise until the voltage value V2 matches the voltage value V1, and the control unit performs a predetermined timeout process if the voltage value V2 does not match the voltage value V1 during the timeout period corresponding to the slope of the rise from when the voltage value V1 starts to rise.

[0018] Note that the above "voltage value V2 matches voltage value V1" includes both the voltage values ​​V1 and V2 being completely the same and the difference between voltage values ​​V1 and V2 being less than a predetermined minute value. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide an inrush current prevention circuit and an electric vehicle charging / discharging device that can correctly determine a timeout regardless of whether the electric vehicle is equipped with an inrush current prevention function. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a block diagram showing the configuration of an inrush current prevention circuit and an electric vehicle charging / discharging device according to an embodiment of the present invention; [Figure 2] 3 is a waveform diagram showing the operation of the inrush current prevention circuit and the charging / discharging device for an electric vehicle according to the embodiment of the present invention. FIG. [Figure 3] FIG. 1 is a block diagram showing the configuration of a conventional inrush current prevention circuit and an electric vehicle charging / discharging device connected to an electric vehicle not equipped with an inrush current prevention function. [Figure 4] 1 is a waveform diagram showing the operation of a conventional inrush current prevention circuit and an electric vehicle charging / discharging device connected to an electric vehicle not equipped with an inrush current prevention function. [Figure 5] FIG. 1 is a block diagram showing the configuration of a conventional inrush current prevention circuit and an electric vehicle charging / discharging device connected to an electric vehicle having an inrush current prevention function. [Figure 6] 1 is a waveform diagram showing the operation of a conventional inrush current prevention circuit and an electric vehicle charging / discharging device connected to an electric vehicle having an inrush current prevention function. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of an inrush current prevention circuit and an electric vehicle charging / discharging device according to the present invention will be described with reference to the accompanying drawings.

[0022] [Example] Figure 1 shows an electric vehicle charging / discharging device 10 according to an embodiment of the present invention. The electric vehicle charging / discharging device 10 is used to charge and discharge a battery 21 mounted on an electric vehicle 20, and as shown in the figure, includes a connector 17 connected to an inlet 22 of the electric vehicle 20, an inrush current prevention circuit 11 that prevents an inrush current from flowing from the battery 21 through the connector 17 when discharging of the battery 21 begins, a relatively large-capacity capacitor 15, and a DC / AC conversion circuit 16.

[0023] The electric vehicle 20 may be a type that has only a contactor C between the battery 21 and the inlet 22, or a type that has a DC / DC conversion circuit 23 with an inrush current prevention function and a contactor C between the battery 21 and the inlet 22.

[0024] The inrush current prevention circuit 11 includes a variable resistor composed of a first relay RL1, a second relay RL2, and a resistor R, a first voltmeter 12 that measures a voltage value V1 of the voltage input to one end of the variable resistor (i.e., the voltage of the first power line L1 connected to the connector 17), a second voltmeter 13 that measures a voltage value V2 of the voltage output from the other end of the variable resistor (i.e., the voltage of the second power line L2 connected to the capacitor 15 and the DC / AC conversion circuit 16), and a control unit 14 that controls the resistance value of the variable resistor (i.e., the opening and closing of the first relay RL1 and the second relay RL2) based on these two voltage values ​​V1 and V2.

[0025] More specifically, the variable resistor is composed of a first relay RL1 and a resistor R that form a series circuit, and a second relay RL2 that is connected in parallel to this series circuit. When the first relay RL1 is in an open state and the second relay RL2 is in a closed state, the resistance value of the variable resistor is substantially zero. On the other hand, when the first relay RL1 is in a closed state and the second relay RL2 is in an open state, the resistance value of the variable resistor is substantially equal to the resistance value of the resistor R. In other words, when the states of the first relay RL1 and the second relay RL2 switch from the former state to the latter state, the resistance value of the variable resistor increases.

[0026] When the control unit 14 detects that the contactor C in the electric vehicle 20 has been closed (i.e., that the battery 21 has started to discharge) based on an increase in the voltage value V1, it closes the first relay RL1 and opens the second relay RL2 (see FIG. 2). As a result, the current flowing from the battery 21 is limited by the variable resistor having a resistance value equivalent to that of the resistor R, and the capacitor 15 is precharged relatively slowly.

[0027] When the control unit 14 detects that the pre-charging is complete based on the fact that the voltage value V2 matches the voltage value V1, it returns the first relay RL1 to the open state and the second relay RL2 to the closed state (see FIG. 2). As a result, from this point on, current flows from the battery 21 to the capacitor 15 and the DC / AC conversion circuit 16 via the variable resistor whose resistance value has become substantially zero.

[0028] Furthermore, the control unit 14 performs a predetermined timeout process if the voltage value V2 does not match the voltage value V1 during the time period corresponding to the gradient of the rise from when the start of discharge of the battery 21 is detected based on the rise of the voltage value V1 until the timeout period corresponding to the gradient of the rise has elapsed.

[0029] More specifically, if the slope of the increase in voltage value V1 is greater than a predetermined threshold, that is, if it is considered that electric vehicle 20 is not equipped with an inrush current prevention function, control unit 14 sets the timeout period to Δt (= time t2 - t0), as shown in Figure 2(A). Δt needs to be set longer than the precharge period (= time t1 - t0), which can be calculated from the resistance value of resistor R and the capacitance value of capacitor 15.

[0030] On the other hand, if the slope of the increase in voltage value V1 is smaller than a predetermined threshold, i.e., if it is considered that electric vehicle 20 is equipped with an inrush current prevention function, control unit 14 sets the timeout period to Δt' (= time t4 - t0), which is longer than Δt, as shown in FIG. 2(B). If electric vehicle 20 is equipped with an inrush current prevention function, it is difficult to predict the pre-charge period (= time t3 - t0). Therefore, Δt' is preferably set to be considerably longer to reliably prevent erroneous timeout determination. In this embodiment, Δt' is set to twice Δt.

[0031] The timeout process performed by the control unit 14 includes, for example, stopping the discharge by returning the contactor C to the open state, and notifying the user of the abnormality.

[0032] Although the embodiments of the inrush current prevention circuit and the charging / discharging device for an electric vehicle according to the present invention have been described above, the configuration of the present invention is not limited to these. [Variations]

[0033] For example, the control unit 14 may set the timeout period to Δt when the rate of increase in the voltage value V1 is greater than a predetermined first threshold, set the timeout period to Δt' (where Δt' > Δt) when the rate of increase in the voltage value V1 is smaller than the first threshold but greater than a predetermined second threshold (where the second threshold < the first threshold), and further set the timeout period to Δt" (where Δt" > Δt') when the rate of increase in the voltage value V1 is smaller than the second threshold. This configuration makes it possible to more reliably detect the occurrence of an abnormality that may cause a timeout while preventing erroneous determination of a timeout.

[0034] Furthermore, the variable resistor does not have to include the first relay RL1 connected in series with the resistor R. In this case, the resistance value of the variable resistor can be increased or decreased simply by opening and closing the second relay RL2. The variable resistor can have any configuration as long as its resistance value can be changed by electrical control. [Explanation of symbols]

[0035] 10 Charging and discharging equipment for electric vehicles 11 Inrush current prevention circuit 12 First voltmeter 13 Second voltmeter 14 Control Unit 15 Capacitor 16 DC / AC conversion circuit 17 Connectors 20 Electric vehicles 21 Battery 22 Inlet 23 DC / DC conversion circuit C Contactor L1 First power line L2 Second power line R resistance RL1 First Relay RL2 Second relay

Claims

1. A variable resistor, a connector for connection to an electric vehicle, connected to one end of the variable resistor; a capacitor and a DC / AC conversion unit connected to the other end of the variable resistor; The voltage value V of the voltage input to one end of the variable resistor １ a first voltmeter for measuring The voltage value V of the voltage output from the other end of the variable resistor ２ a second voltmeter measuring The voltage value V １ , V ２ a control unit that controls the resistance value of the variable resistor based on Equipped with The control unit determines the voltage value V １ starts to rise, the voltage value V ２ is the voltage value V １ increasing the resistance value of the variable resistor until the resistance value matches The control unit also determines the slope of the increase in the voltage value V 1 based on the voltage value V 1 , and calculates the slope of the increase in the voltage value V １ The voltage value V 1 is increased from the time when the voltage value V 1 starts to increase until the time-out period corresponding to the increase slope of the voltage value V 1 has elapsed. ２ is the voltage value V １ If it does not match, a predetermined timeout process is performed. A charging / discharging device for an electric vehicle.

2. The control unit sets the timeout period to Δt when the gradient of the increase is greater than a predetermined threshold, and sets the timeout period to Δt' when the gradient of the increase is smaller than the predetermined threshold.

2. The charging / discharging device for an electric vehicle according to claim 1.

3. the variable resistor includes a first relay and a fixed resistor that form a series circuit, and a second relay that is connected in parallel to the series circuit; When the resistance value of the variable resistor is to be increased, the control unit closes the first relay and opens the second relay, and otherwise opens the first relay and closes the second relay.

3. The charging / discharging device for an electric vehicle according to claim 1 or 2.

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