Switching device, switching system and control method

Abstract

A switching device mounted in a vehicle and disposed between a storage battery and a connector that is connected to a DC power source, said switching device including a transmission path that connects the connector and the storage battery, a solid-state relay provided in the transmission path, a switch provided in the transmission path, a first sensor that measures the current flowing through the solid-state relay or the voltage of the solid-state relay, and a control unit that controls the switching on and off of the solid-state relay, said switch being controlled by an external control signal, and said control unit controlling the solid-state relay on the basis of the control signal and a measured value from the first sensor.

Description

[Technical field]

[0001] The present disclosure relates to a switching device, a switching system, and a control method. [Background technology]

[0002] A secondary battery mounted on a plug-in hybrid vehicle (hereinafter referred to as a plug-in hybrid electric vehicle (PHEV)) or an electric vehicle (hereinafter referred to as an electric vehicle (EV)) is charged by an external power source. Patent Document 1 discloses a charging system for an electric vehicle that can prevent the occurrence of a short-circuit current even if a charging line is short-circuited. Specifically, with reference to FIG. 1, the charging system for an electric vehicle 12 includes a vehicle-side connector 30, charging line switches 28p and 28n, vehicle-side charging lines 46p and 46n, and a driving battery 24. The charging system also includes a vehicle-side voltage sensor 38 provided between the vehicle-side charging lines 46p and 46n, and a charger-side voltage sensor 66 provided between charger-side charging lines 72p and 72n that electrically connect (hereinafter simply referred to as connection) a DC power source 60 and a charger-side connector 62. The charging system further includes a diode 32, a bypass line 48 that bypasses the diode 32, a bypass line switch 34 and a resistive element 36 disposed in the bypass line 48, and an electronic control unit (ECU) 40.

[0003] If a short circuit occurs in the charging line, the charging system can prevent a reverse current (short-circuit current) from flowing from the driving battery 24 to the quick charger 14 by using the diode 32. Furthermore, the charging system can determine whether or not there is an insulation failure (short circuit, etc.) before charging begins. When quick charging is performed, the vehicle-side connector 30 and the charger-side connector 62 are connected, and a close command is output to the charging line switches 28p and 28n and the bypass line switch 34. At this time, if the difference in voltage detected by the vehicle-side voltage sensor 38 and the charger-side voltage sensor 66 exceeds a predetermined threshold, the electronic control device 40 determines that there is a possibility of an insulation failure (short circuit, etc.) in the charging line switch 28p or 28n, the bypass line 48, or the resistive element 36. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-228060 A Summary of the Invention

[0005] A switching device according to one aspect of the present disclosure is mounted on a vehicle and disposed between a connector connected to a DC power source and a storage battery, and includes an electric transmission path connecting the connector and the storage battery, a semiconductor relay provided in the electric transmission path, a switch provided in the electric transmission path, a sensor that measures the current flowing through the semiconductor relay or the voltage of the semiconductor relay, and a control unit that controls the opening and closing of the semiconductor relay, wherein the switch is controlled by a control signal from outside, and the control unit controls the semiconductor relay based on the control signal and the measurement value of the sensor.

[0006] A switching system according to another aspect of the present disclosure includes the switching device described above and a switch control unit that inputs a control signal to the switching device.

[0007] A control method according to yet another aspect of the present disclosure is a control method for a switching device mounted on a vehicle and arranged between a connector connected to a DC power source and a storage battery, the switching device including an electric transmission line connecting the connector and the storage battery, a semiconductor relay provided in the electric transmission line, and a switch provided in the electric transmission line, and including a first control step of controlling the switch using a control signal, a measurement step of measuring a current flowing through the semiconductor relay or a voltage of the semiconductor relay, and a second control step of controlling the semiconductor relay based on the control signal and the measurement value obtained by the measurement step. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a conventional charging system capable of preventing a short circuit current. [Diagram 2] FIG. 2 is a block diagram showing a configuration of an opening and closing device according to the first embodiment of the present disclosure. [Diagram 3] FIG. 3 is a cross-sectional view showing the structure of a metal-oxide-semiconductor field-effect transistor (MOSFET) used in a semiconductor relay. [Figure 4] FIG. 4 is a graph showing voltage-current characteristics when a negative voltage is applied to the drain with respect to the source voltage in the MOSFET shown in FIG. [Diagram 5] FIG. 5 is a flowchart showing an operation when charging the storage battery in the configuration shown in FIG. [Figure 6] FIG. 6 is a timing chart showing the operation of the switching device shown in FIG. [Figure 7] FIG. 7 is a timing chart showing the effect of reducing the threshold value. [Figure 8] FIG. 8 is a block diagram showing a configuration of an opening and closing device according to the second embodiment of the present disclosure. [Figure 9] FIG. 9 is a timing chart showing the operation (occurrence of a short circuit) of the switching device shown in FIG. [Figure 10]FIG. 10 is a timing chart showing the operation (false detection of a short circuit) of the switching device shown in FIG. [Figure 11] FIG. 11 is a block diagram showing a configuration of an opening and closing device according to the third embodiment of the present disclosure. [Figure 12] FIG. 12 is a flowchart showing the operation of the failure determination unit of the switching device shown in FIG. [Figure 13] FIG. 13 is a timing chart showing the operation (normal state) of the switching device shown in FIG. [Figure 14] FIG. 14 is a timing chart showing the operation of the switching device shown in FIG. 11 (when the semiconductor relay is stuck on). [Figure 15] FIG. 15 is a timing chart showing the operation of the switching device shown in FIG. 11 (semiconductor relay stuck in the off state). [Figure 16] FIG. 16 is a block diagram showing a configuration of a switching device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Problem that this disclosure aims to solve] In the charging system described in Patent Document 1, a large current flows through the diode 32 during rapid charging of the driving battery 24. Therefore, the diode 32, which has a relatively large on-resistance, generates a large amount of heat, and a mechanism for cooling the diode 32 must be added, which is costly. In addition to the open / close control of the charging line switches 28p and 28n, it is necessary to control the bypass line switch 34 to turn on and off in order to check the voltage of the storage battery before starting rapid charging, which also causes a problem of complex control for rapid charging.

[0010] Therefore, an object of the present disclosure is to provide a switching device, a switching system, and a control method that can interrupt a short-circuit current without requiring a special cooling mechanism and without complicating control for rapid charging.

[0011] [Effects of this disclosure] According to the present disclosure, it is possible to provide a switching device, a switching system, and a control method that can interrupt a short-circuit current without requiring a special cooling mechanism and without complicating control for rapid charging.

[0012] [Description of the embodiments of the present disclosure] The contents of the embodiments of the present disclosure will be listed and described below. At least a part of the embodiments described below may be arbitrarily combined.

[0013] (1) A switching device according to a first aspect of the present disclosure is mounted on a vehicle and disposed between a connector connected to a DC power source and a storage battery, and includes an electric transmission line connecting the connector and the storage battery, a semiconductor relay provided in the electric transmission line, a switch provided in the electric transmission line, a first sensor for measuring a current flowing through the semiconductor relay or a voltage of the semiconductor relay, and a control unit for controlling opening and closing of the semiconductor relay, the switch being controlled by a control signal from an external source, and the control unit controlling the semiconductor relay based on the control signal and the measurement value of the first sensor. In this way, when a short circuit occurs in the electric transmission line, the electric transmission line can be quickly cut off (opened), and a short-circuit current can be prevented from flowing from the storage battery. In addition, since the on-resistance of the semiconductor relay is relatively small, there is no need to provide a special cooling mechanism as in a configuration in which a charging current is supplied via a diode.

[0014] (2) Preferably, the control unit includes a determination unit that determines whether or not the electric transmission line is short-circuited based on the measurement value of the first sensor, and controls the opening and closing of the semiconductor relay based on the control signal and the determination result by the determination unit. This makes it possible to normally control the semiconductor relay according to the control signal and to turn off the semiconductor relay when a short circuit occurs, thereby interrupting the electric transmission line, without changing the control of a switch provided in the charging line (electric transmission line).

[0015] (3) More preferably, the first sensor includes a voltage sensor, which measures the voltage between the input terminal and the output terminal of the semiconductor relay, and the determination unit determines whether or not there is a short circuit in the electric transmission path based on the voltage measured by the voltage sensor. This allows for rapid detection of a short circuit in the electric transmission path. Also, by determining whether or not there is a short circuit in the electric transmission path using the one-way voltage of the semiconductor relay (a voltage difference that causes a short circuit current, which is zero when a charging current flows), the threshold value for turning off the semiconductor relay (cutting off the electric transmission path) can be set to be smaller than the charging current, and when a short circuit occurs, the semiconductor relay can be quickly turned off to prevent the short circuit current from flowing.

[0016] (4) More preferably, when the determination unit determines that the power transmission path is short-circuited, the control unit controls the opening and closing of the semiconductor relay without considering the control signal. This makes it possible to quickly turn off the semiconductor relay and prevent a short-circuit current from flowing. Even if the semiconductor relay is turned off, this does not affect the state of a switch provided in the charging line, so the switch can be maintained in a closed state. Therefore, if the short-circuit determination is incorrect, charging can be quickly resumed.

[0017] (5) Preferably, the opening and closing control of the semiconductor relay is a cutoff control that opens the semiconductor relay, thereby quickly preventing a short-circuit current from flowing.

[0018] (6) More preferably, the switching device further includes a reset unit that outputs a reset signal when the determination unit determines that the power transmission line is short-circuited, and the control unit controls the semiconductor relay to close when the reset signal is input, and maintains the semiconductor relay in an open state after performing cut-off control multiple times within a predetermined time. This makes it possible to more accurately detect the occurrence of a short circuit and to maintain rapid charging in the event of a false detection.

[0019] (7) More preferably, when the power transmission line is not short-circuited, the control unit performs synchronous control to control the opening and closing of the semiconductor relay in synchronization with the opening and closing of the switch. This makes it unnecessary to change the control of the switch provided in the charging line, and allows charging control to be performed as in the past.

[0020] (8) Preferably, the synchronous control is a control for opening and closing the semiconductor relay based on the control signal without taking into account the measurement value of the first sensor, whereby, in a situation where no short circuit occurs, it is possible to control the switch as in the conventional case.

[0021] (9) More preferably, the switchgear further includes a second sensor that measures a voltage value of a connection node between the switchgear and the semiconductor relay, and a failure determination unit that determines the presence or absence of a failure in the semiconductor relay based on the voltage value detected by the second sensor, and the failure determination unit determines the presence or absence of a failure in the semiconductor relay based on the control signal and the voltage value. This makes it possible to prevent rapid charging from being performed even if rapid charging is instructed when the semiconductor relay is faulty. Therefore, in a fault state in which the semiconductor relay is maintained in the on state (stuck on), it is possible to prevent the occurrence of a short circuit current, and in a fault state in which the semiconductor relay is maintained in the off state (stuck off), it is possible to prevent the body diode from abnormally heating due to the execution of rapid charging.

[0022] (10) A switching system according to a second aspect of the present disclosure includes the above-mentioned switching device and a switch control unit that inputs a control signal to the switching device. This allows the transmission line to be quickly cut off (opened) when a short circuit occurs in the transmission line, and prevents a short-circuit current from flowing from the storage battery. In addition, since the on-resistance of the semiconductor relay is relatively small, there is no need to provide a special cooling mechanism as in a configuration in which a charging current is supplied via a diode.

[0023] (11) A control method according to a second aspect of the present disclosure is a control method for a switchgear mounted on a vehicle and disposed between a connector connected to a DC power source and a storage battery, the switchgear including an electric transmission line connecting the connector and the storage battery, a semiconductor relay provided in the electric transmission line, and a switch provided in the electric transmission line, the control method including a first control step of controlling the switchgear by a control signal, a measurement step of measuring a current flowing through the semiconductor relay or a voltage of the semiconductor relay, and a second control step of controlling the semiconductor relay based on the control signal and the measurement value obtained in the measurement step. This makes it possible to quickly cut off (open) the electric transmission line when a short circuit occurs, and to prevent a short-circuit current from flowing from the storage battery.

[0024] [Details of the embodiment of the present disclosure] In the following embodiments, the same parts are denoted by the same reference numerals, and their names and functions are also the same, so detailed description thereof will not be repeated.

[0025] (First embodiment) (composition) 2, the opening and closing device 100 according to the first embodiment of the present disclosure includes a control unit 102, a semiconductor relay 104, a first sensor 106, a switching unit 108, and electric transmission paths 114a and 114b. The opening and closing device 100 is mounted on a vehicle 140 together with an external ECU 120, a connector 122, a storage battery 124, and a sensor 126. The opening and closing device 100 is disposed on an electric transmission path for connecting a charger 200 to the vehicle 140 to charge the storage battery 124. The vehicle 140 is a PHEV or an EV.

[0026] The control unit 102 includes a determination unit 110 and a drive unit 112. The determination unit 110 has a calculation function. The determination unit 110 performs control to turn off (open) the semiconductor relay 104 based on a predetermined threshold value Vth, as described later. Specifically, the determination unit 110 compares a signal (a one-way voltage V0 described later) input from the first sensor 106 with the threshold value Vth, and outputs a control signal S1 according to the result. That is, if V0≦Vth, the determination unit 110 outputs a low-level (hereinafter referred to as L level) control signal S1, and if V0>Vth, outputs a high-level (hereinafter referred to as H level) control signal S1. The determination unit 110 can be realized by one or more processing circuits. The determination unit 110 can be realized by a calculation element (IC chip such as ASIC or FPGA) with a relatively simple configuration. The determination unit 110 may be realized by a CPU (Central Processing Unit), a microcomputer (hereinafter referred to as microcomputer), or the like.

[0027] The threshold value Vth may be stored in advance, for example, in a memory (not shown) inside the control unit 102. Although the threshold value Vth is a voltage, when a cutoff current is specified, a voltage value (Ith×R) corresponding to the cutoff current (Ith) may be calculated using the on-resistance (R) of the semiconductor relay 104, and the voltage value may be set as the threshold value Vth.

[0028] The threshold value Vth needs to be set to a value within a range in which the semiconductor relay 104, which will be described later, is not damaged. When the storage battery 124 is rapidly charged by the charger 200, the current I flowing through the semiconductor relay 104 during charging is a large charging current (e.g., 200 A). Therefore, in order to prevent the semiconductor relay 104 from being damaged, it is preferable to set the threshold value Vth so that a short-circuit current exceeding the charging current (200 A) does not flow even if the power transmission line is short-circuited. For example, the threshold value Vth may be set to a value equal to or less than the product of the on-resistance of the semiconductor relay 104 and 200 A.

[0029] The drive unit 112 is a circuit for driving the semiconductor relay 104, and receives an output signal (control signal S1) from the determination unit 110, generates a drive signal Vg according to the control signal S1 and a control signal S2 input from an external ECU 120 described later, and outputs the drive signal Vg to the semiconductor relay 104. Specifically, if the control signal S1 is at an L level, a signal at the same level as the control signal S2 is output as the drive signal Vg. If the control signal S1 is at an H level, a signal at an inverted level of the control signal S1 (i.e., an L level) is output as the drive signal Vg, regardless of the level of the control signal S2. The drive signal Vg is used as a signal (gate voltage) that controls the opening and closing of the semiconductor relay 104.

[0030] The semiconductor relay 104 is a relay including a semiconductor element having a switching function. The semiconductor relay 104 is disposed in an electric transmission line 114a connecting one terminal (first terminal) of the multiple terminals of the connector 122 and a positive terminal of the storage battery 124. Here, the semiconductor relay 104 is assumed to be an N-type MOSFET (hereinafter referred to as N-MOSFET) capable of passing a large current. The source S of the semiconductor relay 104 is connected to the opening / closing unit 108, the drain D is connected to the positive terminal of the storage battery 124, and the gate G is connected to the output terminal of the driving unit 112. The semiconductor relay 104 includes a diode 116 that is structurally included in a normal MOSFET. Since the semiconductor relay 104 is an N-MOSFET, the anode of the diode 116 (the body of the N-MOSFET) is connected to the source S, and the cathode is connected to the drain D. As will be described later, when the storage battery 124 is charged, the source S of the semiconductor relay 104 is an input terminal of the charging current, and the drain D is an output terminal of the charging current.

[0031] With reference to Fig. 3, an N-MOSFET that performs the opening and closing function of semiconductor relay 104 will be specifically described. A positive voltage is applied to the source of an N-MOSFET (for example, an N-MOSFET of SiC), and a negative voltage is applied to the drain with the source voltage as a reference. A positive voltage is applied to the gate with the source voltage as a reference. In this state, as shown by the solid arrow in Fig. 3, a current (hereinafter also referred to as drain current) flows from the source to the drain via a channel (an inversion layer formed under the gate in a P-type layer). Since the source voltage is higher than the drain voltage, a forward voltage is applied to the body diode, and although a current also flows via the body diode (see the dashed arrow), the current flowing via the channel with low resistance is predominant.

[0032] Referring to FIG. 4, a graph (voltage-current characteristics) showing the change in drain voltage VD and drain current ID under a constant gate voltage VG changes from the dotted line (VG=0) as shown by the solid line when the gate voltage VG is increased from 0 to V1 (>0) and V2 (>V1). In FIG. 4, the horizontal axis (rightward is positive) represents the drain voltage VD based on the source voltage VS, and the vertical axis (upward is positive) represents the drain current ID, the direction from the source to the drain being positive. The graph in FIG. 4 shows the drain voltage-current characteristics in the region of VD≦0, ID≦0, with point O shown in the upper right as the origin ((VD, ID)=(0,0)). When VG=0, no current flows through the channel, so the graph for VG=0 shows the voltage-current characteristics of the body diode.

[0033] The first sensor 106 detects the voltage between the source S and the drain D of the semiconductor relay 104. Here, the first sensor 106 detects the voltage Vs of the source S and the voltage Vd of the drain D, and generates a unidirectional voltage V0 according to the detected values, taking into account the current direction flowing through the semiconductor relay 104. Specifically, if Vd≥Vs, then V0 = Vd - Vs; if Vd < Vs, then V0 = 0. That is, the unidirectional voltage V0 is the drain voltage with reference to the source voltage, and means the voltage when a current (short-circuit current) flows from the drain D to the source S of the semiconductor relay 104. When a current (charging current) flows from the source S to the drain D of the semiconductor relay 104, the unidirectional voltage V0 is 0. The unidirectional voltage V0 is input from the first sensor 106 to the determination unit 110 as described above.

[0034] The opening / closing unit 108 includes a first switch 108a and a second switch 108b. The first switch 108a is arranged in a power transmission path 114a that connects a first terminal among a plurality of terminals of the connector 122 and the positive terminal of the storage battery 124. The connector 122 has a form that is coupled to a connector 210 described later. For example, if the connector 210 is a plug, then the connector 122 is a socket. The second switch 108b is arranged in a power transmission path 114b that connects a second terminal different from the first terminal among the plurality of terminals of the connector 122 and the negative terminal of the storage battery 124. More specifically, the first switch 108a is arranged between the first terminal of the connector 122 and the source S of the semiconductor relay 104. The first switch 108a and the second switch 108b connect the storage battery 124 and the connector 122 in the closed state, and open the connection between the storage battery 124 and the connector 122 in the open state. The first switch 108a and the second switch 108b are, for example, electromagnetic switches having an electromagnet and mechanical contacts. The opening and closing of the first switch 108a and the second switch 108b are controlled by a control signal S2 from the external ECU 120.

[0035] As described above, the external ECU 120 outputs the control signal S2 for controlling the opening and closing of the first switch 108a and the second switch 108b to the first switch 108a, the second switch 108b and the drive unit 112. That is, the external ECU 120 functions as a switch control unit that controls the first switch 108a and the second switch 108b included in the opening and closing device 100. The external ECU 120 is realized by, for example, a CPU or a microcomputer. The external ECU 120 executes a predetermined program to execute the process described below. The program executed by the external ECU 120 is stored in a non-volatile storage device inside the external ECU 120 or outside the external ECU 120.

[0036] The storage battery 124 is a high-voltage (for example, about 300 V) secondary battery that can be charged and discharged. The storage battery 124 supplies power to a drive mechanism (such as a motor) of the vehicle 140 (PHEV or EV) for the operation thereof.

[0037] The sensor 126 measures the voltage between the power transmission paths 114a and 114b at a predetermined time interval or when an external instruction is received. Upon receiving a request from the outside, the sensor 126 transmits the measurement value to the request source. For example, the external ECU 120 related to quick charging acquires the measurement value of the sensor 126 to check the charging state of the storage battery 124 before starting quick charging. During quick charging, the measurement value of the sensor 126 is used to monitor the charging state of the storage battery 124. The measurement value of the sensor 126 may be transmitted to the charger 200 via the connector 122 and the connector 210 and a communication line 128 described later.

[0038] The charger 200 includes a DC power supply 202, a sensor 204, a control unit 206, power transmission paths 208a and 208b, and a connector 210. The control unit 206 receives instructions to start and stop charging from the external ECU 120 mounted on the vehicle 140 via a communication line 128. The communication line 128 is formed by connecting the wiring in the vehicle 140 and the wiring in the charger 200 by attaching the connector 210 to the connector 122. The DC power supply 202 outputs power (DC) for charging the storage battery 124 under the control of the control unit 206.

[0039] The positive terminal of the DC power supply 202 is connected to the electric transmission line 208a, and the negative terminal is connected to the electric transmission line 208b. The electric transmission lines 208a and 208b are connected to the connector 210. The connector 210 is, for example, a plug, and the electric transmission lines 208a and 208b are, for example, realized as a cable connecting the main body of the charger 200 and the connector 210. The electric transmission line 208a is connected to one terminal (hereinafter referred to as a third terminal) of the multiple terminals of the connector 210, and the electric transmission line 208b is connected to a fourth terminal different from the third terminal of the multiple terminals of the connector 210. By attaching the connector 210 to the connector 122, the first terminal and the second terminal of the connector 122 described above are connected to the third terminal and the fourth terminal of the connector 210, respectively. Therefore, the output power of the DC power supply 202 is transmitted to the storage battery 124 via the first switch 108a and the second switch 108b, and the semiconductor relay 104, which are arranged on the transmission lines 114a and 114b.

[0040] The sensor 204 measures the voltage between the electric transmission lines 208a and 208b. The control unit 206 appropriately uses the measurement value of the sensor 204 to control the DC power supply 202. The control unit 206 may transmit the measurement value of the sensor 204 to the external ECU 120 via the communication line 128.

[0041] (Operation when charging) The operation of opening / closing device 100 during charging will be described with reference to Figures 5 and 6. The process shown in Figure 5 is started when vehicle 140 is stopped (a state in which the vehicle is parked and the drive mechanism is stopped), connector 210 is attached to connector 122, and an operation is performed on an operation device (not shown) to instruct rapid charging. The process shown in Figure 5 is realized by cooperation of the various parts constituting vehicle 140 and charger 200 shown in Figure 2, including opening / closing device 100.

[0042] The waveforms shown in FIG. 6 are, from top to bottom, the control signal S2 output from the external ECU 120, the state of the opening / closing unit 108, the drive signal Vg (gate voltage of the semiconductor relay 104), the state of the semiconductor relay 104, the one-way voltage V0, the control signal S1 output from the determination unit 110, and the current I flowing through the semiconductor relay 104. The horizontal axis represents the time t common to all waveforms. The current I is the drain current, and the direction from the source S to the drain D of the semiconductor relay 104 (the direction from the charger 200 to the storage battery 124) is positive. When I>0, the current I is a charging current for charging the storage battery 124. When I<0, the current I is a short-circuit current output from the storage battery 124.

[0043] During 0≦t<t1, the vehicle 140 is stopped, the control signal S2 is at the L level, and the opening / closing unit 108 is in the open state. At this time, the one-way voltage V0 is 0, the control signal S1 output from the determination unit 110 is at the L level, and as described above, the drive unit 112 outputs a signal (L level) at the same level as the level of the control signal S2. Therefore, the semiconductor relay 104 is off (in a stopped state).

[0044] At t=t1, when rapid charging is instructed as described above, in step 300, the opening / closing unit 108 is closed and the semiconductor relay 104 is turned on. Thereafter, the control proceeds to step 302. Specifically, the external ECU 120 outputs a control signal S2 at the H level, and after a slight delay, the opening / closing unit 108 becomes closed. The control signal S2 is input to the opening / closing unit 108 and at the same time is also input to the drive unit 112. At this time, the one-way voltage V0 output from the first sensor 106 is 0, and the control signal S1 output from the determination unit 110 is at the L level. Therefore, as described above, the drive unit 112 outputs a drive signal Vg (H level) at the same level as the level of the control signal S2. Note that the level (H level or L level) of the drive signal Vg is based on the voltage of the source S. Since the opening / closing unit 108 is mechanical, as shown in FIG. 6, the timing at which the semiconductor relay 104 turns on is earlier than the timing at which the opening / closing unit 108 becomes closed.

[0045] In step 302, the supply of a charging current for fast charging the storage battery 124 is started. Thereafter, the control proceeds to step 304. Specifically, the external ECU 120 instructs the control unit 206 of the charger 200 to supply a charging current via the communication line 128, and in response to this, the charger 200 outputs power from the DC power supply 202. As described above, when the opening / closing unit 108 is closed in step 300, a positive voltage from the DC power supply 202 is applied to the source S of the semiconductor relay 104. Since a positive voltage is applied from the storage battery 124 to the drain D of the semiconductor relay 104, if the positive voltage of the DC power supply 202 is higher than the positive voltage of the storage battery 124 (i.e., if the drain voltage Vd based on the source voltage is negative (Vd<0)), the drive signal Vg becomes H level, and the semiconductor relay 104 is turned on and enters a drive state. Therefore, when power is supplied from the DC power supply 202, a positive current I flows from the source S to the drain D of the semiconductor relay 104 (I=I0 in FIG. 6). This causes the storage battery 124 to be charged (rapid charging by the charger 200). At this time, the current I includes the current flowing through the diode 116, but the current flowing through the channel portion with the smaller resistance is dominant.

[0046] In step 304, a one-way voltage V0 is generated. Specifically, the first sensor 106 detects a voltage difference between the input terminal (source S) and the output terminal (drain D) of the semiconductor relay 104, and generates and outputs the one-way voltage V0 as described above in accordance with the voltage difference. Then, control proceeds to step 306.

[0047] In step 306, it is determined whether or not a short circuit has occurred in the electric transmission line. Specifically, the determination unit 110 determines whether or not a one-way voltage V0 output from the first sensor 106 is equal to or greater than a threshold value Vth, thereby determining whether or not a short circuit has occurred in the electric transmission line. If the determination unit 110 determines that V0≧Vth (short circuit has occurred), it outputs an H-level control signal S1 as described above. If it is determined that V0≧Vth, control proceeds to step 312; otherwise, control proceeds to step 308.

[0048] If no short circuit has occurred, in step 308, the external ECU 120 determines whether or not to end the quick charging. If it is determined to end, control proceeds to step 310, and if not, control returns to step 304. For example, it is determined to end the quick charging when the storage battery 124 is fully charged or when an instruction to end the quick charging is given by operating the operating device.

[0049] In step 310, the opening / closing unit 108 is opened and the semiconductor relay 104 is turned off. Specifically, the external ECU 120 outputs an L-level control signal S2. After that, the program ends. As a result, the opening / closing unit 108 is opened and the semiconductor relay 104 is turned off. Therefore, if no short circuit has occurred and it is not determined that charging should be terminated, steps 304 to 308 are repeatedly executed and the rapid charging state is maintained.

[0050] If it is determined in step 306 that a short circuit has occurred, the semiconductor relay is turned off in step 312. Specifically, as described above, when the drive unit 112 receives an H-level control signal S1 from the determination unit 110, the drive unit 112 outputs an L-level drive signal Vg regardless of the level of the control signal S2 output from the external ECU 120. This quickly turns off the semiconductor relay 104, making it possible to prevent a short-circuit current from flowing. After that, the program ends.

[0051] FIG. 6 shows that rapid charging is executed at t1 < t < t2 (repetition of steps 304, 306, and 308), and it is determined that rapid charging ends at t = t2 (the determination result of step 308 is YES). If the control signal S2 output from the external ECU 120 becomes the L level at t = t2 (see step 310), after a slight delay, the opening / closing part 108 becomes open. At this time, the one-way voltage V0 output from the first sensor 106 is 0, and the control signal S1 output from the determination part 110 is the L level. Therefore, as described above, the driving part 112 outputs a driving signal Vg (L level) of the same level as the level of the control signal S2, and the semiconductor relay 104 turns off (stops). Since the opening / closing part 108 is mechanical, as shown in FIG. 6, the timing at which the semiconductor relay 104 turns off is earlier than the timing at which the opening / closing part 108 becomes closed. That is, a positive voltage from the DC power supply 202 is applied to the source S of the semiconductor relay 104, and a positive voltage from the storage battery 124 is applied to the drain D of the semiconductor relay 104, and the driving signal Vg becomes the L level. As a result, the current I becomes zero.

[0052] Thereafter, when rapid charging is instructed again at t = t3, the control signal S2 output from the external ECU 120 becomes the H level (see step 300). As a result, as described above with respect to t = t1, the opening / closing part 108 becomes closed, the semiconductor relay 104 turns on (driving state), the current I (I = I0) flows, and the storage battery 124 is charged.

[0053] During charging of the storage battery 124, it is assumed that a short circuit occurs in the electric transmission path at t=t4 (the result of the judgment in step 306 is YES). Due to the short circuit, step 312 is executed. That is, the source voltage of the semiconductor relay 104 drops, and the current I decreases (the current flowing through the channel decreases). When the source voltage of the semiconductor relay 104 further drops and becomes lower than the drain voltage, the direction of the current flowing through the channel of the semiconductor relay 104 reverses (the current I changes from positive to negative). At this time, the one-way voltage V0 output from the first sensor 106 becomes greater than 0 (see the timing of t=t5 in FIG. 6). After that, due to the drop in the source voltage of the semiconductor relay 104, the one-way voltage V0 output from the first sensor 106 further increases. When the one-way voltage V0 input from the first sensor 106 becomes equal to or greater than the threshold value Vth, the judgment unit 110 changes the control signal S1 from the L level to the H level. As a result, the drive unit 112 outputs a drive signal Vg at a level (L level) obtained by inverting the level (H level) of the control signal S1, regardless of the control signal S2 input from the external ECU 120. This turns off the semiconductor relay 104, and no channel current flows. Since the state where the drain voltage is greater than the source voltage is a reverse bias state for the body diode, no current flows even through the body diode. In other words, the charging line (electrical transmission path) is cut off. In this state, the opening / closing unit 108 remains in the closed state.

[0054] As described above, when a short circuit occurs in the electric transmission path from the semiconductor relay 104 to the charger 200 side (left side of the semiconductor relay 104), the opening and closing device 100 disposed in the vehicle 140 quickly cuts off the electric transmission path by turning off (opening) the semiconductor relay 104, and can prevent a short-circuit current from flowing from the storage battery 124. In addition, since the electric transmission path can be cut off regardless of the state of the opening and closing unit 108, the state of the opening and closing unit 108 can be maintained even when a short circuit is detected. Therefore, when a short circuit in the electric transmission path is erroneously detected, quick charging can be quickly resumed by simply turning on the semiconductor relay 104.

[0055] Since the on-resistance of the semiconductor relay 104 is relatively small, the amount of heat generated is small even if a large charging current flows through the semiconductor relay 104 during rapid charging of the storage battery 124. Therefore, a cooling device that is required when the charging current flows through a diode as disclosed in Patent Document 1 is not required, and an increase in costs can be suppressed. In addition, since the power transmission path can be quickly cut off before a large short-circuit current flows when a short circuit occurs, a low-voltage product can be used for the switching unit 108, and overall costs can be reduced.

[0056] Furthermore, when charging the storage battery 124, the control of the switching unit 108 and the control of the semiconductor relay 104 are synchronized. That is, the control signal of the switching unit 108 (the control signal S2 from the external ECU 120) is used as is for controlling the semiconductor relay 104. As a result, when no short circuit occurs, there is no need to control the semiconductor relay 104 individually, and it is sufficient to control the switch as in the past, making the control system simple.

[0057] Furthermore, by using the one-way voltage V0 to detect the presence or absence of a short circuit, the threshold value Vth for turning off the semiconductor relay 104 can be set to a value smaller than the voltage difference generated between both terminals (between the source and drain) of the semiconductor relay 104 due to the charging current. For example, when determining the presence or absence of a short circuit based on the absolute value of the voltage difference between both terminals of the semiconductor relay 104 without considering the current direction (i.e., whether the drain voltage is positive or negative), it is necessary to set the threshold value (absolute value) to a value larger than the voltage between both ends of the semiconductor relay 104 during rapid charging in order to prevent the semiconductor relay 104 from being turned off during rapid charging.

[0058] In contrast, by using the one-way voltage V0, the threshold value Vth can be set arbitrarily. For example, the threshold value Vth can be set to a value smaller than the voltage difference between both terminals of the semiconductor relay 104 during quick charging. With reference to FIG. 7, a case where a positive threshold value Vth1 (Vth>Vth1>0) smaller than the above-mentioned threshold value Vth (>0) is used will be described.

[0059] As shown in Fig. 7, similar to Fig. 6, the drive signal Vg, the state of the semiconductor relay 104, the unidirectional voltage V0, the control signal S1, and the current I are shown. In Fig. 7, the waveform when the threshold value is Vth (the same waveform as in Fig. 6) is indicated by a dashed line. In Fig. 7, until a short circuit occurs (until t = t4), the waveform is the same as that in Fig. 6.

[0060] As described above, after t = t4, the current I decreases. At t = t5, I = 0, and then I < 0 and V0 > 0. While V0 < Vth1, the determination unit 110 still outputs a control signal S1 of the L level. When the unidirectional voltage V0 further increases and the determination unit 110 determines that V0 ≥ Vth1, the determination unit 110 outputs a control signal S1 of the H level. As a result, the drive unit 112 outputs a drive signal Vg of the level obtained by inverting the control signal S1 (L level) regardless of the level of the control signal S2, and the semiconductor relay 104 turns off. As a result, the current I becomes 0. At this time, since the threshold value Vth1 is smaller than the threshold value Vth, at the timing of t = t7 which is before t = t6, the semiconductor relay 104 turns off and the current I becomes 0. That is, by setting a smaller threshold value, the power transmission line can be blocked more quickly and the short-circuit current can be prevented.

[0061] In the above description, when a short circuit is detected, the semiconductor relay 104 is turned off, and the case where the opening / closing unit 108 maintains the closed state has been described, but it is not limited thereto. When a short circuit occurs, the opening / closing unit 108 may be opened. For example, a signal line may be provided between the determination unit 110 and the external ECU 120, and when the determination unit 110 outputs the control signal S1 (when a short circuit occurs), a predetermined signal may be transmitted from the determination unit 110 to the external ECU 120. Thereby, the external ECU 120 that has received the predetermined signal can set the control signal S2 to the L level and open the opening / closing unit 108.

[0062] (Second Embodiment) In the first embodiment, the semiconductor relay is quickly turned off when a short circuit is detected, but there is a possibility of false detection. The second embodiment has a function to cut off the short circuit current like the first embodiment, and can also deal with false detection of a short circuit.

[0063] (composition) 8, a switching device 400 according to a second embodiment of the present disclosure includes a control unit 402, a semiconductor relay 104, a first sensor 106, a switching unit 108, and electric transmission paths 114a and 114b. The switching device 400 is mounted on a vehicle 140 together with an external ECU 120, a connector 122, a storage battery 124, and a sensor 126. The switching device 400 is disposed on an electric transmission path for connecting a charger 200 to the vehicle 140 and charging the storage battery 124.

[0064] The control unit 402 includes a determination unit 410, a reset unit 412, and a drive unit 420. The drive unit 420 includes a first drive unit 422 and a second drive unit 424. The opening and closing device 400 is obtained by replacing the control unit 102 and the first sensor 106 in the opening and closing device 100 shown in FIG. 2 with the control unit 402 and the first sensor 406, respectively, and the control unit 402 is obtained by replacing the determination unit 110 and the drive unit 112 in the control unit 102 shown in FIG. 2 with the determination unit 410 and the drive unit 420, respectively, and adding a reset unit 412. In FIG. 8, components with the same reference numerals as those in FIG. 2 have the same functions as those in FIG. 2 and are configured in the same manner. In the following, the same description will not be repeated, and the opening and closing device 400 will be mainly described with respect to the differences from the opening and closing device 100.

[0065] The determination unit 410 has a function of changing the level of the control signal S1 to be output in response to a reset signal S3 input from a reset unit 412 described later, in addition to the same function as the determination unit 110. In the first embodiment (see FIG. 2), the determination unit 110 determines the presence or absence of a short circuit using a one-way voltage V0 input from the first sensor 106, but the determination unit 410 determines the presence or absence of a short circuit using a measurement value of a current (current value I0) input from a first sensor 406 described later. Specifically, the determination unit 410 compares the current value I0 with a negative threshold value Ith (<0) and outputs a control signal S1 according to the result. For example, if I0>Ith, the determination unit 410 outputs an L-level control signal S1, and if I0≦Ith, outputs an H-level control signal S1.

[0066] When the determination unit 410 outputs the control signal S1 at the H level, the determination unit 410 waits for the input of a reset signal S3 (for example, H level) for a predetermined time Δt1. When the reset signal S3 is input, the control signal S1 is set to the L level. If the reset signal S3 is not input, the control signal S1 is maintained at the H level. As will be described later, when a short circuit occurs, the first sensor 406 repeatedly outputs the reset signal S3. When the determination unit 410 changes the control signal S1 from the L level to the H level, for example, three times within a short period of time, the determination unit 410 maintains the control signal S1 at the H level even if a reset signal is input, and outputs a diagnostic signal S4 (for example, H level). The diagnostic signal S4 is input to the external ECU 120.

[0067] The reset unit 412 outputs a reset signal S3 (H level) when a predetermined time Δt2 (Δt2<Δt1) has elapsed since the control signal S1 output from the determination unit 410 became H level. The passage of time may be determined by providing a clock inside the reset unit 412, or may be determined using time information obtained from an external device (such as a clock). Also, the operating clock of the reset unit 412 may be used.

[0068] The first sensor 406 detects the voltage between the source S and drain D of the semiconductor relay 104, similar to the first sensor 106. Unlike the first sensor 106, the first sensor 406 calculates the value of a current I0 flowing through 104 from the detected voltage Vs of the source S and voltage Vd of the drain D. The first sensor 406 inputs the current value I0 to the determination unit 410. As a result, as described above, the first sensor 406 outputs a control signal S1 at a level according to the result of comparing the current value I0 with the threshold value Ith.

[0069] The first drive unit 422 is a circuit for driving the semiconductor relay 104, and has the same function as the drive unit 112. The first drive unit 422 receives the control signal S1 from the determination unit 410, generates a drive signal Vg according to the control signal S1 and the control signal S2 received from the external ECU 120, and outputs the drive signal Vg to the semiconductor relay 104. If the control signal S1 is at an L level, a signal having the same level as the control signal S2 is output as the drive signal Vg. If the control signal S1 is at an H level, a signal having an inverted level of the control signal S1 (i.e., an L level) is output as the drive signal Vg, regardless of the level of the control signal S2. The drive signal Vg is used as a signal (gate voltage) for controlling the opening and closing of the semiconductor relay 104.

[0070] The second drive unit 424 is a circuit for driving the first switch 108a and the second switch 108b constituting the switching unit 108. The second drive unit 424 controls the opening and closing of the first switch 108a and the second switch 108b in response to a control signal S2 from the external ECU 120.

[0071] (Operation when a short circuit occurs) Referring to FIG. 9, the operation for detecting a short circuit when it occurs will be described. The waveforms shown in FIG. 9 are, from top to bottom, the current I flowing through the semiconductor relay 104, the control signal S2 output from the external ECU 120, the drive signal Vg, the control signal S1 output from the determination unit 410, the reset signal S3, and the diagnostic signal S4. The drive signal Vg represents the state (on or off) of the semiconductor relay 104. The horizontal axis represents the time t common to all waveforms. The current I is the drain current, and the direction from the source S to the drain D of the semiconductor relay 104 (the direction from the charger 200 to the battery 124) is positive. When I>0, the current I is a charging current for charging the battery 124. When I<0, the current I is a short-circuit current output from the battery 124.

[0072] During 0≦t<t1, the vehicle 140 is stopped, the control signal S2 is at the L level, and the opening / closing unit 108 is in the open state. At this time, the current value I0 is 0, the control signal S1 output from the determination unit 410 is at the L level, and as described above, the first drive unit 422 outputs a signal (L level) at the same level as the level of the control signal S2. Therefore, the semiconductor relay 104 is off (in a stopped state).

[0073] At t=t1, when rapid charging is instructed, the external ECU 120 outputs a control signal S2 at the H level, and under the control of the second drive unit 424, the opening / closing unit 108 becomes the closed state. The control signal S2 is also input to the first drive unit 422. At this time, the current value I0 output from the first sensor 106 is 0, and the control signal S1 output from the determination unit 410 is at the L level. Therefore, as described above, the first drive unit 422 outputs a drive signal Vg (H level) at the same level as the level of the control signal S2. As a result, the semiconductor relay 104 turns on, and rapid charging is executed during t1<t<t2.

[0074] Assume that a short circuit occurs in the electric transmission path at t=t3 during charging of the storage battery 124. As a result, the source voltage of the semiconductor relay 104 drops, and the current I decreases. Therefore, the current value I0 input from the first sensor 406 to the determination unit 410 decreases. When the source voltage of the semiconductor relay 104 further drops and becomes lower than the drain voltage, the direction of the current flowing through the channel of the semiconductor relay 104 reverses (the current I changes from positive to negative) and further decreases. Therefore, the current value I0 input from the first sensor 406 to the determination unit 410 becomes negative and further decreases. When the current value I0 becomes equal to or less than the negative threshold value Ith (I0≦Ith), the determination unit 410 changes the control signal S1 from L level to H level (hereinafter, also referred to as cutoff control). As a result, the first drive unit 422 outputs the drive signal Vg at a level (L level) obtained by inverting the level (H level) of the control signal S1, regardless of the control signal S2 input from the external ECU 120. Therefore, the semiconductor relay 104 turns off and no channel current flows. When the drain voltage is greater than the source voltage, the body diode is reverse-biased, so no current flows through the body diode. In other words, the charging line (electrical transmission path) is cut off. In this state, the control signal S2 remains at the H level, and the opening / closing unit 108 remains closed.

[0075] After outputting the control signal S1 at H level, the determination unit 410 waits for the input of the reset signal S3 for a time Δt1. When the control signal S1 output from the determination unit 410 becomes H level, the reset unit 412 measures the elapsed time from when the control signal S1 became H level, and outputs the reset signal S3 (H level) when the time Δt2 has elapsed. In response to this, the determination unit 410 performs cutoff control (changes the control signal S1 from H level to L level). As a result, the drive signal Vg becomes H level, the semiconductor relay 104 turns on, and the current I starts to flow, but since a short circuit has occurred, the current I is a short-circuit current, and after a short time, at t=t4, the state becomes the same as that at t=t3. That is, the control signal S1 becomes H level, the drive signal Vg becomes L level, and the semiconductor relay 104 turns off.

[0076] When t4 < t ≤ t5, the operations in the above t3 < t ≤ t4 are repeated. As a result, the determination unit 410 sets the control signal S1 to the H level a total of three times at t = t3, t4, and t5 (three cut-off controls). After that, the determination unit 410 maintains the control signal S1 at the H level even when a reset signal is input, and at t = t6, outputs a diagnosis signal S4 (H level). The diagnosis signal S4 is input to the external ECU 120, and the external ECU 120 sets the control signal S2 to the L level. Thereby, the second drive unit 424 opens the first switch 108a and the second switch 108b.

[0077] (Operation at the time of short-circuit misdetection) With reference to FIG. 10, the operation when the detection of a short-circuit occurrence is a misdetection will be described. The meaning of each waveform shown in FIG. 10 is the same as that in FIG. 9, and the meaning of the horizontal axis is also the same.

[0078] In 0 ≤ t < t2, the operation of the switching device 400 is the same as that in FIG. 9. During t1 ≤ t < t2, rapid charging is executed.

[0079] During the charging of the storage battery 124, assume that at t = t2, due to some reason, the occurrence of a short-circuit is misdetected. For example, assume that although there is actually no short-circuit and a charging current is flowing normally, the current value I0 output from the first sensor 406 becomes less than or equal to the threshold value Ith (I0 ≤ Ith). Then, the determination unit 410 changes the control signal S1 from the L level to the H level. Thereby, the drive voltage Vg becomes the L level, and the semiconductor relay 104 turns off. Also, after the determination unit 410 outputs the H-level control signal S1, the reset signal S3 is output from the first sensor 406 during the time Δt1 while waiting for the input of the reset signal S3.

[0080] When the reset signal S3 is input, the determination unit 410 returns the control signal S1 to the L level at t=t3. This causes the drive signal Vg to become the H level, and the semiconductor relay 104 turns on. After outputting the H level control signal S1, the determination unit 410 waits for the input of the reset signal S3 for a time Δt1. However, since the short circuit does not actually occur and it is a false detection, and no short circuit current flows (I0>Ith), the reset signal S3 is not output. Therefore, the quick charging continues thereafter, and if the storage battery 124 becomes fully charged at t=t4, for example, the external ECU 120 sets the control signal S2 to the L level, and the semiconductor relay 104 turns off. This ends the quick charging.

[0081] As described above, when a short circuit actually occurs in the electric transmission path from the semiconductor relay 104 to the charger 200 side (left side of the semiconductor relay 104), the opening and closing device 400 arranged in the vehicle 140 quickly cuts off the electric transmission path by turning off (opening) the semiconductor relay 104, and can prevent a short circuit current from flowing from the storage battery 124. The occurrence of a short circuit can be detected more accurately by the determination unit 410 determining that a short circuit has occurred after executing cutoff control three times (setting the control signal S1 to H level three times). Furthermore, when the detection of the occurrence of a short circuit is an erroneous detection, quick charging can be continued without being stopped.

[0082] In the above, the determination unit 410 determines that a short circuit has occurred when the cutoff control is executed three times, but this is not limited to the above. In order to avoid erroneous detection, it is sufficient to execute the cutoff control two or more times within a predetermined short period of time, and it may also determine that a short circuit has occurred after executing the cutoff control four or more times.

[0083] In the above, the first sensor 406 measures the current value of the semiconductor relay 104, but the present invention is not limited to this. As with the first sensor 106 of the first embodiment, the sensor 406 may measure the voltage and output the one-way voltage V0. In this case, the determination unit 410, like the determination unit 110, compares the one-way voltage V0 with the threshold value Vth to determine whether or not a short circuit has occurred.

[0084] Third embodiment In the second embodiment, the false detection of a short circuit is addressed, but the semiconductor relay itself may fail. In the third embodiment, like the second embodiment, the short circuit current is interrupted and the false detection of a short circuit can be addressed, and the semiconductor relay failure can also be detected.

[0085] (composition) 11 , a switching device 600 according to a third embodiment of the present disclosure includes a control unit 602, a semiconductor relay 104, a first sensor 106, a switching unit 108, and electric transmission paths 114a and 114b. The switching device 600 is mounted on a vehicle 140 together with an external ECU 120, a connector 122, a storage battery 124, and a sensor 126. The switching device 600 is disposed on an electric transmission path for connecting a charger 200 to the vehicle 140 to charge the storage battery 124.

[0086] The control unit 602 includes a determination unit 410, a reset unit 412, a drive unit 420, a second sensor 604, and a fault determination unit 606. The drive unit 420 includes a first drive unit 422 and a second drive unit 424. The opening and closing device 600 is obtained by replacing the control unit 402 with the control unit 602 in the opening and closing device 400 shown in FIG. 8. The control unit 602 is obtained by adding a second sensor 604 and a fault determination unit 606 to the control unit 402 shown in FIG. 8. In FIG. 11, components with the same reference numerals as those in FIG. 8 have the same functions as those in FIG. 8 and are configured in the same manner. In the following, the same description will not be repeated, and the opening and closing device 600 will mainly be described with respect to the differences from the opening and closing device 400.

[0087] The second sensor 604 detects the voltage of the connection node between the switch 108 and the semiconductor relay 104, and outputs the detection result (voltage value V1) to the failure determination unit 606. Specifically, the second sensor 604 measures the voltage between the connection node of the first switch 108a and the semiconductor relay 104 (source S) arranged on the electric transmission line 114a, and the connection node of the second switch 108b and the storage battery 124 (negative terminal) on the electric transmission line 114b.

[0088] The failure determination unit 606 determines the presence or absence of a failure and the type of failure of the semiconductor relay 104 according to the control signal S2 input from the external ECU 120 and the voltage value V1 input from the second sensor 604. Specifically, when the control signal S2 is at the L level, if the voltage value V1 is at the L level less than the predetermined threshold value Vth2 (V1 < Vth2), the semiconductor relay 104 is normal. If the voltage value V1 is at the H level greater than or equal to the threshold value Vth2 (V1 ≥ Vth2), it is determined that the semiconductor relay 104 has failed. The failure determination unit 606 determines the type of the failure as a failure in which it is on even though the drive signal Vg is at the L level (hereinafter referred to as on-stuck). On the other hand, when the control signal S2 is at the H level, if the voltage value V1 is at the H level, the semiconductor relay 104 is normal. If the voltage value V1 is at the L level (V1 < Vth2), it is determined that the semiconductor relay 104 has failed. The failure determination unit 606 determines the type of the failure as a failure state in which it is off even though the drive signal Vg is at the H level (hereinafter referred to as off-stuck). The threshold value Vth2 is, for example, half of the voltage of the storage battery 124.

[0089] The failure determination unit 606 can be realized by an arithmetic element (IC chip such as ASIC and FPGA) with a relatively simple configuration. The failure determination unit 606 may also be realized by a CPU, a microcomputer, or the like. FIG. 12 shows an example of the operation of the failure determination unit 606. Note that the charger 200 receives an instruction from the vehicle 140 side and starts and stops the output of power. Specifically, when the control unit 206 receives an instruction to start charging from the external ECU 120 via the communication line 128, it discharges the DC power supply 202, and when it receives an instruction to stop charging, it stops the discharge.

[0090] In step 500, the failure determination unit 606 determines whether or not the control signal S2 input from the external ECU 120 is at the H level. If it is determined that it is at the H level, the control proceeds to step 502. Otherwise, the control proceeds to step 504.

[0091] In step 502, the failure determination unit 606 determines whether the voltage value V1 input from the second sensor 604 is equal to or greater than the threshold value Vth2. If it is determined that the voltage value is equal to or greater than the threshold value Vth2 (the semiconductor relay 104 is normal), the control proceeds to step 508. Otherwise, that is, if V1 < Vth2 (the semiconductor relay 104 is in a stuck-off state), the control proceeds to step 506.

[0092] In step 504, the failure determination unit 606 determines whether the voltage value V1 is equal to or greater than the threshold value Vth2 in the same manner as in step 502. If it is determined that the voltage value is equal to or greater than the threshold value Vth (the semiconductor relay 104 is in a stuck-on state), the control proceeds to step 506. Otherwise (the semiconductor relay 104 is normal), the control proceeds to step 508.

[0093] In step 506, the failure determination unit 606 sets the diagnostic signal S4 output to the external ECU 120 to the H level. Thereafter, the control proceeds to step 508.

[0094] In step 508, the failure determination unit 606 determines whether an end instruction has been received. If it is determined that an end instruction has been received, the failure determination unit 606 stops operating. Otherwise, the control returns to step 500. The failure determination unit 606 determines that an end instruction has been received, for example, when the operating device 140 is operated and a power-off instruction is issued.

[0095] As described above, the failure determination unit 606 determines the presence or absence and type of failure of the semiconductor relay 104 according to the control signal S2 and the voltage value V1, and outputs a diagnostic signal S4 at the H level to the external ECU 120 in the event of a failure. When an on-stuck occurs in the semiconductor relay 104, a short circuit occurs, and even if the opening / closing device 600 detects it, the short-circuit current cannot be interrupted. Also, when an off-stuck occurs in the semiconductor relay 104, current flows through the body diode of the semiconductor relay 104 during rapid charging, which may cause excessive heat generation. Therefore, it is preferable to be able to detect the on-stuck and off-stuck states.

[0096] As described above, when the failure determination unit 606 determines that the semiconductor relay 104 is in a failure state, it outputs a diagnosing signal S4 to the external ECU 120. Even if the external ECU 120 receives an instruction for rapid charging and outputs an H-level control signal S2, it does not instruct the control unit 206 to start charging. The external ECU 120 may set the control signal S2 to an L-level. Also, if the external ECU 120 has output an L-level control signal S2, it does not set the control signal S2 to an H-level even if it receives an instruction for rapid charging, but maintains it at an L-level. In either case, the external ECU 120 may present a warning.

[0097] (normal operation) With reference to FIG. 13, the operation during quick charging when the semiconductor relay is normal will be described. The waveforms shown in FIG. 13 represent, from the top, the current I flowing through the semiconductor relay 104, the charging voltage (the output voltage of the charger 200), the control signal S2 output from the external ECU 120, the state of the semiconductor relay 104, the voltage value V1 output from the second sensor 604, and the diagnostic signal S4. The horizontal axis represents time t, which is common to all the waveforms. Here, it is assumed that no short circuit occurs. When the semiconductor relay 104 is normal, the on / off state of the semiconductor relay 104 is determined by the level of the drive signal Vg, but when the semiconductor relay 104 is faulty, the on / off state of the semiconductor relay 104 is not directly related to the level of the drive signal Vg. When a short circuit occurs, the opening / closing device 600 operates in the same manner as the opening / closing device 400 (see FIG. 9 and FIG. 10).

[0098] When rapid charging is instructed at \(t = t1\), the external ECU 120 outputs a control signal S2 at the H level, and under the control of the second drive unit 424, the opening / closing unit 108 enters the closed state. The control signal S2 is also input to the first drive unit 422. At this stage, since the external ECU 120 has not yet instructed the control unit 206 to start charging, no charging voltage is output from the charger 200, the current value I0 output from the first sensor 106 is 0, and the control signal S1 output from the determination unit 410 is at the L level. Therefore, the first drive unit 422 outputs a drive signal Vg (H level) at the same level as the level of the control signal S2. As a result, the semiconductor relay 104 turns on, the voltage of the battery 124 is detected by the second sensor 604, and the voltage value V1 output from the second sensor 604 becomes the H level. Therefore, the diagnostic signal S4 is maintained at the L level. At time \(t2\), the external ECU 120 instructs the control unit 206 of the charger 200 to start charging. As a result, the voltage Vch is supplied from the charger 200, and rapid charging is executed at \(t2 < t < t3\).

[0099] After that, rapid charging continues. When the storage battery 124 is fully charged at \(t = t3\), the external ECU 120 instructs the control unit 206 to stop charging and sets the control signal S2 to the L level. As a result, the charging voltage becomes zero, the semiconductor relay 104 turns off, and rapid charging ends.

[0100] (Operation in the on-stuck state) With reference to FIG. 14, the operation during rapid charging when the semiconductor relay 104 is in the on-stuck state will be described. The meaning of each waveform shown in FIG. 14 is the same as that in FIG. 13, and the meaning of the horizontal axis is also the same. Here, it is assumed that rapid charging is not being executed.

[0101] At t=t1, if the semiconductor relay 104 becomes stuck-on due to some reason, the voltage of the storage battery 124 (the voltage of the positive terminal) is applied to the connection node between the first switch 108a and the semiconductor relay 104. Therefore, the voltage value V1 output from the second sensor 604 becomes H level. In response to this, since the control signal S2 is at L level, the failure determination unit 606 determines whether or not the voltage value V1 from the second sensor 604 is maintained at H level for a predetermined time Δt3. Since the voltage value V1 is at H level even after the time Δt3 has elapsed, the failure determination unit 606 sets the diagnosing signal S4 to H level at t=t2. In response to this, the external ECU 120 maintains the control signal S2 at L level (does not set the control signal S2 to H level even when a command for quick charging is received). Therefore, quick charging can be prevented from being performed when the semiconductor relay 104 is stuck-on. The external ECU 120 can indicate that the semiconductor relay 104 is stuck on.

[0102] (Operation in stuck off state) The operation when a quick charge command is issued when the semiconductor relay is stuck off will be described with reference to Fig. 15. The meaning of each waveform shown in Fig. 15 is the same as that in Fig. 13, and the horizontal axis also has the same meaning.

[0103] Assume that at t=t1, the semiconductor relay 104 is stuck off due to some reason. At this time, the process shown in FIG. 12 is executed, but quick charging is not performed and the control signal S2 and the voltage value V1 are both at L level, so a fault (stuck off) is not detected. At t=t2, when quick charging is instructed, the external ECU 120 sets the control signal S2 to H level. As a result, the drive voltage Vg becomes H level, but the semiconductor relay 104 is stuck off and the external ECU 120 has not yet instructed the control unit 206 to start charging, so no charging voltage is output. Therefore, the voltage value V1 output from the second sensor 604 remains at L level. The fault determination unit 606 determines whether the voltage value V1 from the second sensor 604 is maintained at L level for a time Δt3 after the control signal S2 becomes H level. Because the voltage value V1 does not become H level but remains L level even after the time Δt3 has elapsed, the failure determination unit 606 sets the diagnosing signal S4 to H level at t=t3. In response to this, the external ECU 120 receives an instruction for rapid charging, but does not instruct the control unit 206 of the charger 200 to start charging. In addition, the external ECU 120 returns the control signal S2 from H level to L level at t=t4. The external ECU 120 can present that the semiconductor relay 104 is stuck off.

[0104] As described above, if semiconductor relay 104 is in a faulty state, switching device 600 can prevent rapid charging from being executed even if rapid charging is instructed. Therefore, if semiconductor relay 104 is stuck off, it is possible to prevent a situation in which current is passed through the body diode of semiconductor relay 104 during rapid charging, causing heat generation that is greater than expected. Furthermore, if semiconductor relay 104 is stuck on, this can be displayed, so that semiconductor relay 104 can be quickly replaced and repaired. Therefore, it is possible to prevent a problem from occurring in which a short circuit occurs when semiconductor relay 104 is stuck on and switching device 600 detects this, in which the short circuit current cannot be interrupted.

[0105] If the semiconductor relay 104 is normal, the switching device 600 operates in the same manner as the switching device 400. That is, if a short circuit occurs, the semiconductor relay 104 is turned off (opened) to quickly cut off the electric transmission path, thereby preventing a short circuit current from flowing from the storage battery 124. Also, if the detection of the occurrence of a short circuit is an erroneous detection, quick charging can be continued without being stopped.

[0106] In the above, the second sensor 604 and the failure determination unit 606 are included in the control unit 602. However, the present invention is not limited to this. The second sensor 604 and the failure determination unit 606 may be disposed outside the control unit 602.

[0107] In the above, the external ECU 120 instructs the control unit 206 of the charger 200 to start and stop the quick charging, but the present invention is not limited to this. When the connector 210 and the connector 122 are connected and the first switch 108a is on, the control unit 206 can detect a voltage value corresponding to the voltage value V1 by a predetermined pin of the connector 210 that is connected to the first switch 108a. Therefore, the control unit 206 may determine the start and stop of the power supply according to the voltage of the predetermined pin of the connector 210. In this way, if the failure determination unit 606 does not detect a failure of the semiconductor relay 104 and the voltage of the predetermined pin remains zero (a state in which the voltage of the storage battery 124 cannot be detected) even though the semiconductor relay 104 is on, it can be determined that the opening and closing unit 108 is faulty.

[0108] (Modification) In the third embodiment, when a failure occurs in the semiconductor relay 104, the failure determination unit 606 outputs the H-level diagnostic signal S4 to the external ECU 120, but the present invention is not limited to this. In the opening / closing device according to the modified example, the failure determination unit 606 outputs the H-level diagnostic signal S4 to the external ECU 120 and opens the opening / closing unit 108. With reference to FIG. 16, the opening / closing device 700 according to the modified example is obtained by adding a signal line from the failure determination unit 606 to the second drive unit 424 as shown by the dashed line in the opening / closing device 600 shown in FIG. 12. The other configurations of the opening / closing device 700 are the same as those of the opening / closing device 600.

[0109] When the failure determination unit 606 of the switching device 700 outputs the diagnosis signal S4, it outputs, for example, an H-level control signal S5 to the second drive unit 424. In response to this, the second drive unit 424 controls the switching unit 108 to the open state regardless of the level of the control signal S2. This allows the switching unit 108 to be quickly opened when a failure has occurred in the semiconductor relay 104. This makes it possible to avoid the problem of not being able to cut off the short-circuit current when a short circuit occurs due to a failure of the semiconductor relay 104.

[0110] In the above, the case where the opening / closing unit 108 is in the closed state when the control signal S2 is at the H level has been described, but the present invention is not limited to this. It is only necessary that the level of the control signal S2 that opens the opening / closing unit 108 is different from the level of the control signal S2 that closes the opening / closing unit 108. For example, the opening / closing unit 108 may be configured to be in the closed state when the control signal S2 is at the L level. In this case, when the control signal S1 is at the L level (when no short circuit occurs), the driving unit 112 may output a driving signal Vg (H level) at a level obtained by inverting the input control signal S2 (L level) to the gate G of the semiconductor relay 104.

[0111] In the above description, the determination unit 110 outputs a control signal S1 of the H level if V0 ≥ Vth, and outputs a control signal S1 of the L level if V0 < Vth. However, the present invention is not limited to this. It is only necessary that the control signal S1 is configured to be output at different levels according to whether V0 ≥ Vth. For example, the determination unit 110 may output a control signal S1 of the L level if V0 ≥ Vth, and output a control signal S1 of the H level if V0 < Vth. In that case, if the control signal S1 is at the H level, the driving unit 112 outputs a driving signal Vg at the same level as the level of the input control signal S2 (or the level obtained by inverting the control signal S2), and if the control signal S1 is at the L level, the driving unit 112 may output a driving signal Vg (L level) at the same level as the control signal S1. Thereby, when the power transmission line is short-circuited, the gate G of the semiconductor relay 104 can be set to the L level to cut off the power transmission line. Note that the same applies to the process in which the determination unit 410 outputs the control signal S1 according to the result of comparing the current value I0 with the threshold value Ith. It is only necessary that the control signal S1 is configured to be output at different levels according to whether I0 ≤ Ith.

[0112] In the above description, the case where the semiconductor relay 104 is disposed between the storage battery 124 (positive electrode terminal) and the first switch 108a has been described, but the present invention is not limited to this. The semiconductor relay 104 may be disposed between the storage battery 124 and the second switch 108b. In that case, the drain D of the semiconductor relay 104 may be connected to the second switch 108b, and the source S may be connected to the negative electrode terminal of the storage battery 124.

[0113] In the above, the case where an N-MOSFET is used for the semiconductor relay 104 has been described, but the present invention is not limited to this. A P-type MOSFET (hereinafter referred to as a P-MOSFET) may be used for the semiconductor relay 104. In this case, for example, the source S of the semiconductor relay (P-MOSFET) is connected to the positive terminal of the storage battery 124, the drain D is connected to the first switch 108a, and a negative voltage is applied to the gate G with the voltage of the source S as a reference. Note that, for the body diode formed in the P-MOSFET, the direction from the drain to the source (the direction from the first switch 108a to the positive terminal of the storage battery 124) is the forward direction. Therefore, similar to the case where an N-MOSFET is used for the semiconductor relay 104, a short-circuit current can be prevented even if a short circuit occurs in the electric transmission path.

[0114] In the above, the semiconductor relay is configured using a MOSFET, but is not limited thereto. Any element may be used as long as it functions as a switch under external control, has a small on-resistance, and functions as a diode when off. For example, a semiconductor relay using a thyristor, a triac, or the like may be used. Also, an element that functions as a switch under external control and has a small on-resistance may be connected in parallel to a diode. By arranging a semiconductor relay configured in this way in a power transmission line such that the anode of the diode is connected to the charger side and the cathode of the diode is connected to the storage battery side, it is possible to prevent a short-circuit current when a short circuit occurs in the power transmission line.

[0115] Although the present disclosure has been described above by explaining the embodiments, the above-mentioned embodiments are merely examples, and the present disclosure is not limited to only the above-mentioned embodiments. The scope of the present disclosure is indicated by each claim in the scope of claims, taking into consideration the description of the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the wording described therein. [Explanation of symbols]

[0116] 12 Electric vehicles 14 Quick charger 24 Running battery 28n, 28p Charging line switch 30 Vehicle side connector 32, 116 Diode 34 Bypass line switch 36 Resistance element 38 Vehicle side voltage sensor 40 Electronic control device 46n, 46p Vehicle side charging line 48 Bypass Line 60, 202 DC power supply 62 Charger side connector 66 Charger side voltage sensor 72n, 72p Charger side charging line 100, 400, 600, 700 Switchgear 102, 206, 402, 602 Control unit 104 Semiconductor Relay 106, 406 First sensor 108 Opening and Closing Section 108a 1st switch 108b 2nd switch 110, 410 Judgment section 112, 420 Drive unit 114a, 114b, 208a, 208b Electric transmission line 120 External ECU 122, 210 Connectors 124 Battery 126, 204 Sensors 128 Communication Line 140 vehicles 200 charger 300, 302, 304, 306, 308, 310, 312, 500, 502, 504, 506, 508 steps 412 Reset section 422 First Drive Unit 424 Second Drive Unit 604 Second Sensor 606 Failure determination section D Drain G Gate I current I0 Current value ID Drain current V0 One-way voltage V1 voltage value VD Drain voltage VG Gate voltage Vg drive signal S Source S1, S2, S5 control signals S3 Reset signal S4 Diagnostic signal Δt1, Δt2, Δt3 Time

Claims

1. A switching device mounted on a vehicle and disposed between a connector connected to a DC power source and a storage battery, a transmission path connecting the connector and the storage battery; a semiconductor relay provided in the transmission line; A switch provided in the electric transmission line; A first sensor for measuring a voltage of the semiconductor relay; a control unit for controlling opening and closing of the semiconductor relay, The switch is controlled by an external control signal, The control unit is a determination unit that determines whether or not the electrical transmission line is short-circuited based on a measurement value of the first sensor; controlling opening and closing of the semiconductor relay based on the control signal and a result of the determination by the determination unit; the first sensor includes a voltage sensor; The voltage sensor measures a voltage between an input terminal and an output terminal of the semiconductor relay, The first sensor generates a unidirectional voltage from the voltage between the input terminal and the output terminal of the semiconductor relay; The determination unit determines whether or not a short circuit occurs in the electric transmission line based on the one-way voltage, The unidirectional voltage is equal to the voltage between the input terminal and the output terminal of the semiconductor relay when a short circuit current occurs, and is zero when a charging current occurs.

2. The switching device according to claim 1 , wherein the control unit performs opening and closing control of the semiconductor relay without taking the control signal into consideration when the determination unit determines that the electric transmission line is short-circuited.

3. The switching device according to claim 2 , wherein the opening and closing control of the semiconductor relay is a cut-off control that opens the semiconductor relay.

4. A reset unit that outputs a reset signal in response to the determination unit that the electrical transmission line is short-circuited, The control unit is In response to the input of the reset signal, the semiconductor relay is closed. The switching device according to claim 3 , wherein the semiconductor relay is maintained in an open state after the cutoff control is executed a plurality of times within a predetermined time period.

5. The switchgear according to claim 1 , wherein, in a state in which the electric transmission line is not short-circuited, the control unit performs synchronous control for controlling opening and closing of the semiconductor relay in synchronization with opening and closing of the switch.

6. The switching device according to claim 5 , wherein the synchronous control is control for opening and closing the semiconductor relay based on the control signal without taking into account the measurement value of the first sensor.

7. a second sensor for measuring a voltage value of a connection node between the switch and the semiconductor relay; a failure determination unit that determines whether or not the semiconductor relay has a failure based on the voltage value detected by the second sensor, The switching device according to claim 1 , wherein the failure determination unit determines whether or not the semiconductor relay has a failure based on the control signal and the voltage value.

8. An opening and closing device according to any one of claims 1 to 7; a switch control unit that inputs the control signal to the switchgear.

9. A method for controlling a switching device mounted on a vehicle and disposed between a connector connected to a DC power source and a storage battery, comprising the steps of: The opening and closing device includes: a transmission path connecting the connector and the storage battery; a semiconductor relay provided in the transmission line; A switch provided in the electric transmission line, a first control step of controlling the switch by a control signal; a measuring step of measuring a voltage of the semiconductor relay; a determination step of determining whether or not a short circuit exists in the electrical transmission line based on the measured value obtained in the measurement step; a second control step of controlling opening and closing of the semiconductor relay based on the control signal and a result of the determination step, The measuring step includes: measuring a voltage between an input terminal and an output terminal of the semiconductor relay; generating a unidirectional voltage from the voltage between an input terminal and an output terminal of the semiconductor relay; The determining step includes a step of determining whether or not a short circuit is present in the electric transmission line based on the one-way voltage, The unidirectional voltage is equal to the voltage between the input terminal and the output terminal of the semiconductor relay when a short circuit current occurs, and is zero when a charging current occurs.

Images