JP6333746B2 - SWITCH DEVICE, POWER CONVERSION DEVICE, AND SWITCH SHORT JUDGMENT METHOD - Google Patents

Description

  The present invention relates to a switch device including a transformer to which an AC voltage is applied from a power system, and a pair of switches for disconnecting the first winding of the transformer from the power system, and a power including the switch device. The present invention relates to a conversion device and a switch short-circuit determination method.

  In recent years, power converters that convert DC power generated by power generation devices such as solar panels and cogeneration devices and DC power from power storage devices into AC power linked to the power system and supply them to the power load in the home have become widespread. ing. Bidirectional power converters that can convert AC power from the power system to charge storage batteries, convert DC power discharged from the storage batteries, and supply them to the power load have begun to be used.

  Such a power converter is prohibited from continuing an independent operation in a state where it is connected to the power system in order to ensure safety when the power system fails. For this reason, the power converter is provided with a disconnect relay for disconnecting from the power system.

  On the other hand, if a relay contact opens or closes a circuit to which a high voltage is applied or a circuit through which a large current flows, the contact may be welded by arc discharge, so whether or not the relay contact of the disconnect relay is welded. It is very important to be able to judge.

  On the other hand, in Patent Document 1, when the operation of the inverter circuit unit connected to the system via the disconnection switch (corresponding to the disconnection relay) is stopped and the disconnection switch is turned off, A grid-connected inverter device (corresponding to a power conversion device) that determines that an abnormality such as welding has occurred in a disconnecting switch when the voltage between the switch and the inverter circuit is greater than a predetermined threshold is disclosed.

  Further, in Patent Document 2, a pair of relay switches (corresponding to disconnection relays) that connect the inverter device to the system is controlled to open, the inverter device is stopped, and one relay switch is controlled to close. Disclosed is a grid-connected inverter device that determines that the other relay switch has failed due to welding or the like when the voltage of a capacitor connected to the DC input side of the inverter device exceeds a predetermined voltage when time has elapsed Has been.

JP 2004-187362 A International Publication No. 2013/001820

  However, the technique disclosed in Patent Document 1 has a problem that it cannot be determined as abnormal when only one of the two relay contacts included in the disconnect switch is welded. In addition, in the technique disclosed in Patent Document 2, it takes longer than the charging time of the capacitor from the time when one of the relay switches is controlled to be closed until the determination of welding is completed. There was a problem.

  The present invention has been made in view of such circumstances, and an object of the present invention is to quickly and separately determine whether or not a plurality of switches for disconnecting from the power system are short-circuited. An object of the present invention is to provide a possible switch device, a power conversion device including the switch device, and a switch short-circuit determination method.

  The switch device according to the present invention includes a transformer to which an AC voltage is applied from a power system, a pair of switches for disconnecting the first winding of the transformer from the power system, and each of the pair of switches. A switching device including a control unit that controls on and off, and a detection unit that detects a voltage of the second winding of the transformer, and the control unit alternately turns on the pair of switches sequentially. It is characterized by comprising: ON means; and means for determining whether or not the voltage detected by the detection unit is greater than a predetermined threshold each time the ON means is turned ON.

  In the switch device according to the present invention, the power system is a single-phase three-wire system, the first winding has a midpoint, and the midpoint is disconnected from the neutral line of the power system. A second switch for determining whether or not the voltage detected by the detection unit is smaller than a second threshold, and the ON unit is configured by the determination unit. It is characterized by being turned on when it is determined to be small.

  A power conversion device according to the present invention is a power conversion device comprising the above-described switch device, and a voltage converter that converts a DC voltage applied from the outside into an AC voltage and applies it to the second winding, A second detection unit configured to detect a voltage between a pair of terminals opposite to the first winding side in the pair of switches, and the control unit performs the second detection every time the on-unit is turned on. It has a means to determine whether the voltage which the part detected is larger than a 3rd threshold value.

  A power conversion device according to the present invention is a power conversion device comprising the above-described switch device, and a voltage converter that converts a DC voltage applied from the outside into an AC voltage and applies it to the second winding, The voltage between the first and second terminals of the pair of terminals opposite to the first winding side in the pair of switches and the terminal on the opposite side to the middle point side in the second switch. The control section includes a second on means for turning on the second switch, and the first and second detectors when the second on means is turned on. And second determination means for determining whether or not the voltage detected by each detector is greater than a fifth threshold value.

  In the power conversion device according to the present invention, when the control unit determines that none of the voltages is greater than the fifth threshold, the control unit includes the switch including the first or second terminal. When the means is turned on, and when the means is turned on, or when the second determination means determines that any voltage is greater than the fifth threshold, the voltage detected by the first or second detector is And a means for determining whether or not the value is larger than a sixth threshold value.

  The power conversion device according to the present invention includes a transformer, a pair of switches having one terminal pair connected to both ends of the first winding of the transformer, and a control for controlling on and off of each of the pair of switches. And a voltage converter that converts a DC voltage applied from the outside into an AC voltage and applies the second voltage to the second winding of the transformer, between the other terminal pairs in the pair of switches A second detection unit for detecting a voltage; and the control unit detects an ON means for sequentially turning on the pair of switches, and the second detection unit detects each time the ON means is turned on. And a means for determining whether or not the voltage is greater than a third threshold value.

  The power conversion device according to the present invention includes a transformer, a pair of switches in which one terminal pair is connected to both ends of the first winding of the transformer, and one terminal at the midpoint of the first winding. A second switch connected, a control unit for controlling on and off of each of the pair of switches and the second switch, a DC voltage applied from the outside is converted into an AC voltage, and the second of the transformer In a power converter provided with the voltage converter applied to a coil | winding, the voltage between each 1st and 2nd terminal among the other terminal pairs in the said pair of switch, and the other terminal in the said 2nd switch The control section includes a second on means for turning on the second switch, and the first and second detectors when the second on means is turned on. It is determined whether the voltage detected by each detector is greater than the fifth threshold value. A second determination unit configured to turn on the switch including the first or second terminal when the second determination unit determines that any voltage is not greater than the fifth threshold; When the means is turned on, or when the second determination means determines that any voltage is greater than the fifth threshold, the voltage detected by the first or second detector is greater than the sixth threshold Means for determining whether or not.

  A switch short-circuit determination method according to the present invention includes a transformer to which a single-phase two-wire AC voltage is applied from a power system, and a pair of switches for disconnecting the first winding of the transformer from the power system. In a method for detecting a short circuit of each of the switches in a switch device including a switch and a control unit that controls on and off of each of the pair of switches, a detection unit that detects a voltage of the second winding of the transformer The pair of switches are alternately turned on sequentially, and each time the pair of switches are turned on, the voltage detected by the detection unit is compared with a predetermined threshold, and the pair of switches is turned on based on the comparison result. It is characterized by determining whether the other switch is short-circuited.

  The switch short-circuit determination method according to the present invention solves from the power system a transformer to which a single-phase three-wire AC voltage is applied from the power system, and both ends and a middle point of the first winding of the transformer. A switch device comprising a pair of switches and a second switch for lining up, and a controller for controlling on and off of each of the pair of switches and the second switch, and each of the pair of switches and the second switch In the method for detecting a short circuit, a detection unit for detecting the voltage of the second winding of the transformer is prepared, and it is determined whether or not the voltage detected by the detection unit is smaller than a second threshold value. In this case, the pair of switches are alternately turned on sequentially and each time the pair of switches are turned on, the voltage detected by the detection unit is compared with a predetermined threshold value, and the pair of switches is turned on based on the comparison result. Whichever switch or And judging whether the second switch is shorted.

  The switch short-circuit determination method according to the present invention includes a transformer, a pair of switches in which one terminal pair is connected to both ends of the first winding of the transformer, and one at the midpoint of the first winding. A second switch to which a terminal is connected, a control unit for controlling on and off of each of the pair of switches and the second switch, and a DC voltage applied from the outside is converted into an AC voltage to convert the transformer In a method of detecting a short circuit of each of the pair of switches and the second switch in a power conversion device including a voltage converter applied to the second winding, the first and second terminals of the other terminal pairs in the pair of switches First and second detectors for detecting a voltage between each of two terminals and another terminal of the second switch are prepared, the second switch is turned on, and the first and second detectors are turned on Compare each detected voltage and the fifth threshold Based on the comparison result, it is determined whether or not each of the pair of switches is short-circuited, and when neither of the pair of switches is short-circuited, the switch including the first or second terminal is turned on, When the switch is turned on, or when any of the voltages detected by the first and second detectors is larger than the fifth threshold, the voltage detected by the first or second detector and the sixth threshold And determining whether or not the second switch is short-circuited based on the comparison result.

In the present invention, a pair of switches for disconnecting the transformer from the power system is connected between the first winding of the transformer and the power system, and the detection unit is the second of the transformer. Detect winding voltage. In this state, the control unit sequentially turns on one and the other of the pair of switches and determines whether or not the voltage detected by the detection unit is greater than a predetermined threshold each time it is turned on.
Thus, when one of the pair of switches is turned on, when the other is short-circuited, a voltage is applied from the power system to the detection unit via the pair of switches and the transformer, whereas the pair of switches When the other side of the switch is not short-circuited, no voltage is applied to the detection unit. For this reason, when the voltage detected by the detection unit when the control unit sequentially turns on one and the other of the pair of switches is greater than a predetermined threshold, the switch that is not on of the pair of switches is short-circuited. It is determined.

In the present invention, the power system is a single-phase three-wire system, and the first winding of the transformer has a midpoint. Between this midpoint and the neutral line of the power system, the transformer A second switch for disconnecting the instrument from the power system is further connected. In this state, when the voltage detected by the detection unit is smaller than the second threshold value, it is determined that two or more switches of the pair of switches and the second switch are not short-circuited. When two or more switches are not short-circuited, the control unit sequentially turns on one and the other of the pair of switches, and each time it is turned on, whether the voltage detected by the detection unit is greater than a predetermined threshold value Determine.
Thus, when one of the pair of switches is turned on, when the other or the second switch is short-circuited, it is detected from the power system via one of the pair of switches and the other or the second switch. While a voltage is applied to the part, no voltage is applied to the detection part when the other of the pair of switches and the second switch are not short-circuited. Therefore, when the voltage detected by the detection unit when the control unit sequentially turns on one and the other of the pair of switches is greater than the second threshold, the switch that is not turned on or the second switch of the pair of switches It is determined that the switch is short-circuited.

In the present invention, one terminal pair of the pair of switches is connected to both ends of the first winding of the transformer, and the other terminal pair is disconnected from the single-phase two-wire power system. Yes. Then, the inverter converts the DC voltage applied from the outside into an AC voltage and applies it to the second winding of the transformer, and the second detector is connected to another terminal pair (that is, the first winding side) The voltage between the opposite terminal pair) is detected. In this state, the control unit sequentially turns on and off one of the pair of switches, and determines whether or not the voltage detected by the second detection unit is greater than the third threshold each time it is turned on.
Thereby, when one of the pair of switches is turned on, when the other is short-circuited, the voltage is applied from the inverter to the second detection unit via the transformer and the pair of switches. When the other of the pair of switches is not short-circuited, no voltage is applied to the second detection unit. For this reason, when the voltage detected by the second detection unit when the control unit sequentially turns on one and the other of the pair of switches is greater than the third threshold, the switch that is not turned on of the pair of switches It is determined that a short circuit has occurred.

In the present invention, one terminal pair of the pair of switches is connected to both ends of the first winding of the transformer, and one terminal of the second switch is connected to the midpoint of the first winding. The other terminal pair in the pair of switches and the other terminal in the second switch are disconnected from the single-phase three-wire power system. Then, the inverter converts the DC voltage applied from the outside into an AC voltage and applies it to the second winding of the transformer, and the other terminal pair (that is, the terminal pair opposite to the first winding side) Of these, the first and second detectors detect the voltage between each of the first and second terminals and the other terminal (that is, the terminal opposite to the first winding side). In this state, the control unit turns on the second switch, and determines whether the voltage detected by each of the first and second detectors when turned on is greater than the fifth threshold value.
Thus, when the second switch is turned on, when the switch including the first terminal (or the second terminal) is short-circuited among the pair of switches, the second switch is further connected from the inverter via the transformer. When the voltage is applied to the first detector (or the second detector) via the switch and the short-circuited switch, when neither of the pair of switches is short-circuited, the first and second detections are performed. No voltage is applied to the instrument. For this reason, when the voltage detected by the first detector (or the second detector) when the control unit turns on the second switch is greater than the fifth threshold, the first terminal (or the first switch) of the pair of switches It is determined that the switch including the two terminals is short-circuited.

In the present invention, when the voltage detected by each of the first and second detectors when the control unit turns on the second switch is not greater than the fifth threshold, both the pair of switches are short-circuited. It is determined that it is not. When the control unit turns on the switch including the first terminal of the pair of switches or the switch including the first terminal of the pair of switches is short-circuited, the first detection is performed. The controller determines whether the voltage detected by the device is greater than a sixth threshold value. Separately from this, when the control unit turns on the switch including the second terminal or when the switch including the second terminal of the pair of switches is short-circuited, the voltage detected by the second detector is the sixth A control part determines whether it is larger than a threshold value.
Thereby, when the switch including the first terminal (or the second terminal) is turned on, or when the switch including the first terminal (or the second terminal) is short-circuited, the second switch is short-circuited. The voltage is applied from the inverter to the first detector (or the second detector) via the transformer and further via the switch including the first terminal (or the second terminal) and the second switch. On the other hand, when the second switch is not short-circuited, no voltage is applied to the first detector (or the second detector). For this reason, when the control unit turns on the switch including the first terminal (or the second terminal) or when the switch including the first terminal (or the second terminal) is short-circuited, the first detector (or the first detector) When the voltage detected by the (two detectors) is larger than the sixth threshold, it is determined that the second switch is short-circuited.

According to the present invention, when the voltage detected by the detection unit when the control unit turns on one and the other of the pair of switches is higher than a predetermined voltage, it is determined that the other and one of the pair of switches are short-circuited. The
Therefore, it is possible to quickly and separately determine whether or not a plurality of switches for disconnecting from the power system are short-circuited.

It is a block diagram which shows the structural example of the power converter device which concerns on Embodiment 1 of this invention. It is a flowchart which shows the process sequence of CPU which determines the presence or absence of the short circuit of a relay contact in the switch apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the process sequence of CPU which determines the presence or absence of the short circuit of a relay contact in the switch apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structural example of the power converter device which concerns on Embodiment 2 of this invention. It is a flowchart which shows the process sequence of CPU which determines the presence or absence of the short circuit of a relay contact with the switch apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows the process sequence of CPU which determines the presence or absence of the short circuit of a relay contact with the switch apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structural example of the power converter device which concerns on Embodiment 3 of this invention. It is a flowchart which shows the process sequence of CPU which determines the presence or absence of the short circuit of a relay contact with the switch apparatus which concerns on Embodiment 3 of this invention. It is a flowchart which shows the process sequence of CPU which determines the presence or absence of the short circuit of a relay contact with the switch apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structural example of the power converter device which concerns on Embodiment 4 of this invention. It is a flowchart which shows the process sequence of CPU which determines the presence or absence of the short circuit of a relay contact in the switch apparatus which concerns on Embodiment 4 of this invention. It is a flowchart which shows the process sequence of CPU which determines the presence or absence of the short circuit of a relay contact in the switch apparatus which concerns on Embodiment 4 of this invention.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of a power conversion device according to Embodiment 1 of the present invention. 1a is a power converter, and the power converter 1a includes an inverter 2 (corresponding to a voltage converter) 2 that converts a DC voltage from an external DC power source into an AC voltage, an output terminal on the AC side of the inverter 2, and And a switch device 3a for turning on / off the connection between the single-phase two-wire power system 4a. The inverter 2 may have the function of a converter that converts an AC voltage into a DC voltage.

  The inverter 2 includes switching elements such as IGBTs (Insulated Gate Bipolar Transistors), MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors), and power transistors in an H-bridge. In the first embodiment, transistors Q1, Q2, Q3, Q4 made of IGBT are used as switching elements. The collectors and emitters of the transistors Q1, Q2, Q3, and Q4 are connected to the cathodes and anodes of commutation (reflux) diodes (hereinafter simply referred to as diodes) D1, D2, D3, and D4.

  The collectors of the transistors Q1 and Q3 included in each of the upper arms of the H bridge are connected to one end of the smoothing capacitor C1 and to the positive side of the external DC power supply. The emitters of the transistors Q2 and Q4 included in the lower arms of the H bridge are connected to the other end of the smoothing capacitor C1 and to the negative side of the external DC power supply.

  The gates of the transistors Q1, Q2, Q3, and Q4 are connected to an inverter drive circuit 34 described later. The emitter of the transistor Q3 is connected to the collector of the transistor Q4 and to one end of the inductor L1. The emitter of the transistor Q1 is connected to the collector of the transistor Q2 and to one end of the inductor L2. The emitters of the transistors Q1 and Q3 (that is, the collectors of the transistors Q2 and Q4) are output terminals on the AC side of the inverter 2. A capacitor C2 is connected between the other ends of the inductors L1 and L2. The inductors L1 and L2 and the capacitor C2 constitute a filter circuit.

  The switch device 3a includes a transformer (hereinafter referred to as an insulation transformer) T1a in which the first winding N1a and the second winding N2 are insulated, and a pair of switches for disconnecting the first winding N1a from the power system 4a. Relays (corresponding to a pair of switches) RLY1 and RLY2, a control unit 30 that controls on and off of each of the relays RLY1 and RLY2, and a detection unit VM0 that detects the voltage of the second winding N2. The pair of relays is, for example, an electromagnetic switch, an electromagnetic contactor, a general-purpose electromagnetic relay, or a semiconductor relay, but may be a switching element such as a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor).

  In the insulation transformer T1a, the turns ratio of the first winding N1a and the second winding N2 is 1: 1. Thereby, the voltage of the 1st coil | winding N1a and the voltage of the 2nd coil | winding N2 become substantially equal. The turns ratio is not limited to 1: 1.

  In the relays RLY1 and RLY2, one terminal pair at each relay contact is connected to both ends of the first winding N1a, the other terminal pair is connected to the power load 43 and the power system via the main breaker 40a. 4a. Below, the alternating voltage of the electric power grid | system 4a is set to voltage Va.

  The detection unit VM0 detects an AC voltage and outputs a detection voltage. When the inverter 2 has detection means for detecting the voltage at the output terminal on the AC side, this detection means may also serve as the detection unit VM0.

  The control unit 30 includes a CPU 31. The CPU 31 stores a ROM 32 for storing information such as a control program, a RAM 33 for storing temporarily generated information, an inverter drive circuit 34 for driving the inverter 2, and a signal input / output unit. The I / O 35, the relay drive circuit 36 that drives each of the relays RLY1 and RLY2, and an A / D converter 37 that converts an analog voltage into a digital voltage value are bus-connected.

  The inverter drive circuit 34 drives the gates of the transistors Q3 and Q2 with a PWM signal so as to perform PWM control during a period in which the transistors Q3 and Q2 are simultaneously turned on in one half-wave period of the AC voltage output from the inverter 2. The inverter drive circuit 34 also drives the gates of the transistors Q1 and Q4 with a PWM signal so as to PWM control the period in which the transistors Q1 and Q4 are simultaneously turned on in the other half-wave period of the AC voltage output from the inverter 2. To do. In this case, the gates of the transistors Q1 and Q2 and the gates of the transistors Q3 and Q4 are driven by complementary PWM signals. However, in the first embodiment, in order to turn off the inverter 2, a signal for turning off the transistors Q1 to Q4 is given to each gate.

  The I / O 35 is connected to both ends of the auxiliary contact that outputs a contact signal indicating the on / off state of the main breaker 40a (connection of one end is omitted in the figure).

  The relay drive circuit 36 is connected to the relay coils of the relays RLY1 and RLY2. The relay drive circuit 36 supplies excitation current to these relay coils to drive each of them separately, whereby each of the relays RLY1 and RLY2 is turned on.

  The A / D converter 37 converts the analog detection voltage from the detection unit VM0 into a digital detection voltage value.

  In the above-described configuration, the control unit 30 turns off the inverter 2 in advance, and when the relays RLY1 and RLY2 are turned on, an AC voltage is applied from the power system 4a to the isolation transformer T1a via the main breaker 40a. Make sure. When the AC voltage is not applied, it is determined that the power failure has occurred, the main breaker 40a is not turned on, or at least one of the relay contacts of the relays RLY1 and RLY2 has an open failure. Next, the control unit 30 once turns off the relays RLY1 and RLY2, and then sequentially turns on and off one of the relays RLY1 and RLY2, and based on the voltage of the second winding N2 when turned on, the relays RLY1 and RLY2 respectively. Whether or not the relay contacts are short-circuited is determined separately.

  For example, when only the relay RLY1 is turned on and the relay contact of the relay RLY2 is short-circuited, approximately Va is supplied to the detection unit VM0 from the power system 4a via the relay contacts RLY1 and RLY2 and the isolation transformer T1a. Is applied. For this reason, when the voltage detected by the detection unit VM0 is approximately Va, that is, when the voltage is larger than a predetermined threshold, it is determined that the relay contact of the relay RLY2 is short-circuited.

  Similarly, when only the relay RLY2 is turned on, when the voltage detected by the detection unit VM0 is greater than a predetermined threshold, it is determined that the relay contact of the relay RLY1 is short-circuited. The first cause of short-circuiting of the relay contact is welding, but the cause of short-circuiting is not limited to welding.

  If the power system 4a is not in a power outage state and the main breaker 40a is already turned on, for example, by a power outage detection unit (not shown) and the I / O 35, the control unit 30 pre-insulates the insulation transformer. There is no need to confirm that an alternating voltage is applied to T1a. In this case, when the short circuit determination of the relay contacts of the relays RLY1 and RLY2 is completed and the inverter 2 is arranged in parallel with the power system 4a, if the voltage of approximately Va is not detected by the detection unit VM0, the relays RLY1 and RLY2 It is determined that at least one of the relay contacts has an open fault.

Below, operation | movement of the control part 30 mentioned above is demonstrated using the flowchart which shows it. The following processing is executed by the CPU 31 in accordance with a control program stored in advance in the ROM 32.
2 and 3 are flowcharts showing the processing procedure of the CPU 31 for determining whether or not the relay contact is short-circuited in the switch device 3a according to Embodiment 1 of the present invention. The processes of FIGS. 2 and 3 are started as appropriate as one of the self-diagnosis programs in the switch device 3a.

  When the processing of FIG. 2 is started, the CPU 31 turns off the inverter 2 by the inverter drive circuit 34 (S10), and further turns on the relays RLY1 and RLY2 by the relay drive circuit 36 (S11). Thereafter, the CPU 31 waits for a predetermined time longer than the operation time of the relays RLY1 and RLY2 and the off time of the inverter 2 (S12), and then detects the voltage of the second winding N2 by the detection unit VM0 (S13). In order for the CPU 31 to wait for a predetermined time, for example, the CPU 31 may wait for a predetermined time after a timer (not shown) starts counting (the same applies hereinafter).

  Next, the CPU 31 determines whether or not there is voltage application from the power system 4a based on whether or not a voltage that is not substantially zero is detected (S14). When no voltage is applied from the power system 4a (S14: NO), the CPU 31 shifts the process to step S12 in order to wait until the voltage is applied. When there is voltage application from the power system 4a (S14: YES), the CPU 31 turns off the relays RLY1 and RLY2 (S15).

  3, the CPU 31 turns on the relay RLY1 by the relay drive circuit 36 (S20: corresponding to the ON means), and waits for a predetermined time longer than the operation time of the relays RLY1 and RLY2 (S21). Further, after detecting the voltage of the second winding N2 by the detection unit VM0 (S22), the CPU 31 turns off the relay RLY1 (S23).

  Next, the CPU 31 determines whether or not the detection result by the detection unit VM0 is greater than a predetermined threshold (S24: equivalent to a determination unit). If the detection result is greater than the predetermined threshold (S24: YES), the relay contact of the relay RLY2 After storing in the RAM 33 that the short circuit (simply represented as relay RLY2 in the figure: the same applies below) is stored in the RAM 33 (S25), the processing in FIG. 3 is terminated.

  On the other hand, when the detection result by the detection unit VM0 is not larger than the predetermined threshold (S24: NO), the CPU 31 turns on the relay RLY2 by the relay drive circuit 36 (S26: equivalent to the on means), and the operations of the relays RLY1 and RLY2 Wait for a predetermined time longer than the time (S27). Further, after detecting the voltage of the second winding N2 by the detection unit VM0 (S28), the CPU 31 turns off the relay RLY2 (S29).

  Next, the CPU 31 determines whether or not the detection result by the detection unit VM0 is larger than a predetermined threshold (S30: equivalent to a determination unit). If the detection result is larger than the predetermined threshold (S30: YES), the relay contact of the relay RLY1 3 is stored in the RAM 33 (S31), and the process of FIG. The predetermined threshold value may be different between steps S24 and S30. Even when the detection result is not greater than the predetermined threshold value in step S30 (S30: NO), the CPU 31 ends the process of FIG.

  In the above-described flowchart, it is determined whether or not the relay contacts are short-circuited in the order of the relays RLY1 and RLY2 in the processing from step S20 to S31. First, the relay contact of the relay RLY2 is determined whether or not there is a short circuit. You may make it perform.

As described above, according to the first embodiment, the insulation transformer T1a is disconnected from the power system 4a between the first winding N1a of the insulation transformer T1a and the single-phase two-wire power system 4a. The relay contacts of the relays RLY1 and RLY2 are connected, and the detection unit VM0 detects the voltage of the second winding N2 of the insulation transformer T1a. In this state, the control unit 30 sequentially turns on and off one of the relays RLY1 and RLY2, and determines whether or not the voltage detected by the detection unit VM0 is greater than a predetermined threshold each time it is turned on.
As a result, when one of the relays RLY1 and RLY2 is turned on, when the other relay contact is short-circuited, the detection unit from the power system 4a via the relay contacts of the relays RLY1 and RLY2 and the isolation transformer T1a When a voltage is applied to VM0 while the other relay contact is not short-circuited, no voltage is applied to the detection unit VM0. For this reason, when the voltage detected by the detection unit VM0 when the control unit 30 sequentially turns on one and the other of the relays RLY1 and RLY2 is greater than a predetermined threshold, the relay contact of the relays RLY1 and RLY2 that is not on Is determined to be short-circuited.
Accordingly, it is possible to quickly and separately determine whether or not a plurality of switches for disconnecting from the power system 4a are short-circuited.

(Embodiment 2)
While the first embodiment is a mode in which an AC voltage is applied to the switch device 3a from the single-phase two-wire power system 4a, the second embodiment is a switch device from the single-phase three-wire power system. This is a mode in which an alternating voltage is applied.
FIG. 4 is a block diagram illustrating a configuration example of the power conversion device according to the second embodiment of the present invention. In the figure, 1b is a power conversion device, and the power conversion device 1b includes an inverter 2 and a switch device 3b for turning on / off the connection between the output side of the AC side of the inverter 2 and the single-phase three-wire power system 4b. Is provided.

  The switch device 3b includes an insulation transformer T1b having a midpoint between the first winding N1b and the second winding N2, and a relay RLY1 for disconnecting both ends of the first winding N1b from the power system 4b. Controls ON / OFF of RLY2, relay RLY3 (corresponding to the second switch) for disconnecting the midpoint of the first winding N1b from the neutral line of the power system 4b, and relays RLY1, RLY2, and RLY3 And a detection unit VM0 that detects the voltage of the second winding N2.

  In the insulation transformer T1b, the turns ratio of the first winding N1b and the second winding N2 is 1: 1. As a result, the voltage of the first winding N1b is equal to the voltage of the second winding N2. The turns ratio is not limited to 1: 1.

  In the relays RLY1 and RLY2, one terminal pair of each relay contact is connected to both ends of the first winding N1b, the other terminal pair is connected to the power load 43 and the power system via the main breaker 40b. 4b. In the relay RLY3, one terminal of the relay contact is connected to the middle point of the first winding N1b, and the other terminal is connected to the neutral line of the power system 4b via the main breaker 40b. Power loads 41 and 42 are connected between the other terminal of the relay contact of the relay RLY3 and the other terminal pair of the relay contacts of the relays RLY1 and RLY2.

  The relay coil of the relay RLY3 is connected to the relay drive circuit 36. The relay drive circuit 36 drives the relay coil by passing an exciting current, whereby the relay RLY3 is turned on.

  Since other configurations of the power conversion device 1b are the same as those of the power conversion device 1a in the first embodiment, the portions corresponding to those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. The I / O 35 is connected to both ends (one connection is omitted in the figure) of the auxiliary contact that outputs a contact signal indicating the on / off state of the main breaker 40b. Moreover, let the alternating voltage of the electric power grid | system 4b be the voltage Vb.

  In the above-described configuration, when the control unit 30 turns off the inverter 2 in advance and turns on the relays RLY1 to RLY3, an AC voltage is applied from the power system 4b to the isolation transformer T1b via the main breaker 40b. Make sure. If no AC voltage is applied, it is determined that a power failure has occurred, the main breaker 40b has not been turned on, or at least two relay contacts of relays RLY1 to RLY3 have an open failure. The Next, when the control unit 30 turns off the relays RLY1 to RLY3, if the voltage detected by the detection unit VM0 is not smaller than the second threshold value, an AC voltage is applied from the power system 4b to the isolation transformer T1b. Therefore, it is determined that at least two relay contacts of relays RLY1 to RLY3 are short-circuited.

  Specifically, when the relay contacts of each of the at least two relays are short-circuited, the voltage Vb is applied across the first winding N1b, or one end and the middle point of the first winding N1b Since a voltage of Vb / 2 is applied between them, the voltage applied to the detection unit VM0 is always substantially Vb. In this case, it cannot be determined for which two relays the relay contacts are short-circuited or for all the relays the relay contacts are short-circuited.

  On the other hand, when the control unit 30 turns off the relays RLY1 to RLY3 and the voltage detected by the detection unit VM0 is smaller than the second threshold value, an AC voltage is applied to the first winding N1b from the power system 4b. Therefore, it can be said that the relay contacts of two or more of the relays RLY1 to RLY3 are not short-circuited. In this case, the control unit 30 sequentially turns on and off one of the relays RLY1 and RLY2, and the relay contacts of the relays RLY1, RLY2, and RLY3 are short-circuited based on the voltage of the second winding N2 when turned on. Whether or not each is determined.

  For example, when only the relay RLY1 is turned on and the relay contact of the relay RLY2 or RLY3 is short-circuited, the relay contact of the relay RLY1, the relay contact of the relay RLY2 or RLY3, and the insulation transformer T1b are connected from the power system 4b. Thus, the voltage Vb is applied to the detection unit VM0. For this reason, when the voltage detected by the detection unit VM0 is approximately Vb, that is, when the voltage is larger than the predetermined threshold, it is determined that the relay contact of the relay RLY2 or RLY3 is short-circuited. This determination result is taken as a result 23 (there is a short circuit in any / no short circuit in either).

  Similarly, when only the relay RLY2 is turned on, when the voltage detected by the detection unit VM0 is greater than a predetermined threshold, it is determined that the relay contact of the relay RLY1 or RLY3 is short-circuited. This determination result is taken as a result 13 (Any short is present / Any short is not present). The relay contact short circuit determination according to the combination of the result 23 and the result 13 is as follows.

(A) When both the result 23 and the result 13 are short-circuited, it is determined that the relay contact of the relay RLY3 is short-circuited.
(B) When only the result 23 has a short circuit, it is determined that the relay contact of the relay RLY2 is short-circuited.
(C) When only the result 13 has a short circuit, it is determined that the relay contact of the relay RLY1 is short-circuited.
(D) When both the result 23 and the result 13 are not short-circuited, it is determined that none of the relay contacts of the relays RLY1, RLY2, and RLY3 are short-circuited.

  If the power system 4b is not in a power outage state and the main breaker 40b is already turned on, for example, by a power outage detection unit (not shown) and the I / O 35, the control unit 30 is preliminarily configured with an insulation transformer. There is no need to confirm that an AC voltage is applied to T1b. In this case, when the short circuit determination of each relay contact from the relays RLY1 to RLY3 is completed and the inverter 2 is arranged in parallel with the power system 4b, when the voltage of approximately Vb is not detected by the detection unit VM0, the relay RLY1 It is determined that at least two of the relay contacts up to RLY3 are open failures.

Below, operation | movement of the control part 30 mentioned above is demonstrated using the flowchart which shows it.
5 and 6 are flowcharts showing the processing procedure of the CPU 31 for determining whether or not the relay contact is short-circuited in the switch device 3b according to the second embodiment of the present invention. However, the determination processes from (a) to (d) described above are self-explanatory and will not be described with reference to flowcharts.

  Of the processing from step S40 to S44 shown in FIG. 5, the processing except for step S41 is substantially the same as the processing from step S10 to S14 shown in FIG. A part of is omitted. Further, among the processing from step S50 to S60 shown in FIG. 6, the processing except step S55 is substantially the same as the processing from step S20 to S30 shown in FIG. 3 of the first embodiment. A part of the description is omitted.

  When the process of FIG. 5 is activated, the CPU 31 turns off the inverter 2 (S40) and turns on the relays RLY1 to RLY3 (S41). Thereafter, the CPU 31 waits for a predetermined time longer than the operation time of the relays from the relays RLY1 to RLY3 and the off time of the inverter 2 (S42), and then detects the voltage of the second winding N2 by the detection unit VM0 (S43). .

  Next, the CPU 31 determines whether or not there is voltage application from the power system 4b (S44), and when there is no voltage application (S44: NO), the process proceeds to step S42. When voltage is applied from the power system 4b (S44: YES), the CPU 31 turns off the relays RLY1 to RLY3 (S45), and waits for a predetermined time longer than the operation time of the relays from the relays RLY1 to RLY3 (S46). Thereafter, the voltage of the second winding N2 is detected again (S47).

  Next, the CPU 31 determines whether or not the detection result by the detection unit VM0 is smaller than the second threshold (S48: corresponding to the determination unit), and if not smaller than the second threshold (S48: NO), the relay RLY1 The fact that the relay contacts of at least two of the relays up to RLY3 are short-circuited is stored in the RAM 33 (S49), and the processing of FIG.

  On the other hand, when the detection result by the detection unit VM0 is smaller than the second threshold (S48: YES), the CPU 31 turns on the relay RLY1 (S50), waits for a predetermined time (S51), and proceeds to FIG. After detecting the voltage of the winding N2 (S52), the relay RLY1 is turned off (S53).

  Next, the CPU 31 determines whether or not the detection result by the detection unit VM0 is greater than a predetermined threshold (S54). If the detection result is greater than the predetermined threshold (S54: YES), the relay contact of the relay RLY2 or RLY3 is short-circuited. Is stored in the RAM 33 (S55), the process of FIG. The predetermined threshold value may be different between steps S54 and S60.

  When the detection result by the detection unit VM0 is not larger than the predetermined threshold (S54: NO), the CPU 31 turns on the relay RLY2 (S56), waits for a predetermined time (S57), and detects the voltage of the second winding N2. (S58) Thereafter, the relay RLY2 is turned off (S59).

  Next, the CPU 31 determines whether or not the detection result by the detection unit VM0 is larger than a predetermined threshold (S60). If the detection result is larger than the predetermined threshold (S60: YES), the relay contact of the relay RLY1 or RLY3 is short-circuited. Is stored in the RAM 33 (S61), the process of FIG. Even when the detection result is not greater than the predetermined threshold value in step S60 (S60: NO), the CPU 31 ends the process of FIG.

As described above, according to the second embodiment, the power system 4b is a single-phase three-wire system, and the first winding N1b of the insulation transformer T1b has a midpoint. The midpoint and the power system 4b A relay contact of a relay RLY3 for disconnecting the insulating transformer T1b from the power system 4b is further connected between the neutral line and the neutral line. In this state, when the voltage detected by the detection unit VM0 is smaller than the second threshold value, it is determined that the relay contacts of each of two or more relays from the relays RLY1 to RLY3 are not short-circuited. When the relay contact of each of the two or more relays is not short-circuited, the control unit 30 sequentially turns on and turns on one of the relays RLY1 and RLY2, and the voltage detected by the detection unit VM0 is predetermined. It is determined whether it is larger than the threshold value.
Accordingly, when one of the relays RLY1 and RLY2 is turned on, when the other relay contact or the relay contact of the relay RLY3 is short-circuited, one relay contact of the relays RLY1 and RLY2 from the power system 4b and the other When the voltage is applied to the detection unit VM0 via the relay contact of the relay RLY3 or the relay contact of the relay RLY3, the voltage is applied to the detection unit VM0 when the other relay contact and the relay contact of the relay RLY3 are not short-circuited. Not applied.
Therefore, when the voltage detected by the detection unit VM0 when the control unit 30 sequentially turns on one and the other of the relays RLY1 and RLY2 is larger than the second threshold, the relay that is not turned on among the relays RLY1 and RLY2 It becomes possible to determine that the relay contact is short-circuited for the relay RLY3.

(Embodiment 3)
In the first embodiment, an AC voltage is applied from the power system 4a side to the relay contacts of the relays RLY1 and RLY2, whereas in the third embodiment, the relay contacts of the relays RLY1 and RLY2 On the other hand, an AC voltage is applied from the inverter 2 side via the insulating transformer T1a.
FIG. 7 is a block diagram showing a configuration example of the power conversion apparatus according to Embodiment 3 of the present invention. In the figure, 1c is a power converter, and the power converter 1c includes a switch device 3c for turning on / off the connection between the inverter 2 and the AC-side output terminal of the inverter 2 and the single-phase two-wire power system 4a. Is provided.

  The switching device 3c includes an insulating transformer T1a, relays RLY1 and RLY2 in which one terminal pair at each relay contact is connected to both ends of the first winding N1a of the insulating transformer T1a, a control unit 30, and the relay contact A detection unit (corresponding to a second detection unit) VM3 that detects a voltage between another terminal pair (that is, a terminal pair opposite to the first winding N1a side) is provided. Each of the relay contacts of the relays RLY1 and RLY2 has the other terminal pair connected to the power load 43.

The switch device 3c may simply turn on / off the connection between the inverter 2 and the power load 43. The detection unit VM0 that detects the voltage of the second winding N2 of the insulating transformer T1a is not essential.
Since the other configuration of the power conversion device 1c is the same as that of the power conversion device 1a in the first embodiment, portions corresponding to those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. Hereinafter, the AC voltage output from the inverter 2 is referred to as a voltage Vc.

  In the configuration described above, when the control unit 30 turns off the inverter 2 and the relays RLY1 and RLY2, no voltage is applied to the relay contacts of the relays RLY1 and RLY2 from the power system 4a via the main breaker 40a. And confirm that the main breaker 40a is open. As a result, the possibility that the inverter 2 becomes a single operation is eliminated. Next, when the control unit 30 turns on the inverter 2 and applies a voltage between a pair of terminals at the relay contacts of the relays RLY1 and RLY2, and then sequentially turns on and turns on one and the other of the relays RLY1 and RLY2. Whether or not the relay contacts of the relays RLY1 and RLY2 are short-circuited is individually determined based on the voltage between the other terminal pairs (that is, the voltage on the power load 43 side).

  For example, when only the relay RLY1 is turned on and the relay contact of the relay RLY2 is short-circuited, the inverter VM3 is connected to the detection unit VM3 via the isolation transformer T1a and the relay contacts of the relays RLY1 and RLY2. A voltage is applied. For this reason, when the voltage detected by the detection unit VM3 is approximately Vc, that is, when the voltage is larger than the third threshold, it is determined that the relay contact of the relay RLY2 is short-circuited. Similarly, when only the relay RLY2 is turned on, when the voltage detected by the detection unit VM3 is larger than the third threshold, it is determined that the relay contact of the relay RLY1 is short-circuited.

Below, operation | movement of the control part 30 mentioned above is demonstrated using the flowchart which shows it.
8 and 9 are flowcharts showing a processing procedure of the CPU 31 for determining whether or not the relay contact is short-circuited in the switch device 3c according to the third embodiment of the present invention. Of the processes from steps S80 to S91 shown in FIG. 9, the processes except for steps S82, S84, S88, and S90 are substantially the same as the processes from steps S20 to S31 shown in FIG. 3 of the first embodiment. Since they are the same, a part of the description is omitted.

  When the process of FIG. 8 is started, the CPU 31 turns off the inverter 2 by the inverter drive circuit 34 (S70), and further turns off the relays RLY1 and RLY2 (S71). Thereafter, the CPU 31 waits for a predetermined time (S72), and then detects the voltage on the power load 43 side by the detection unit VM3 (S73).

  Next, the CPU 31 determines whether or not there is a voltage application from the power system 4a (S74). If there is a voltage application (S74: YES), the CPU 31 performs processing in step S72 in order to wait until there is no voltage application. Move. When there is no voltage application from the power system 4a (S74: NO), the CPU 31 determines whether the main breaker 40a is opened by taking in the contact signal of the auxiliary contact of the main breaker 40a by the I / O 35 (S75). ), When it is not opened (S75: NO), it waits until it is opened. When the main breaker 40a is opened (S75: YES), the CPU 31 turns on the inverter 2 (S76).

  9, the CPU 31 turns on the relay RLY1 (S80), and waits for a predetermined time longer than the operation time of the relay RLY1 and the on time of the inverter 2 (S81). Further, after detecting the voltage on the power load 43 side by the detection unit VM3 (S82), the CPU 31 turns off the relay RLY1 (S83).

  Next, the CPU 31 determines whether or not the detection result by the detection unit VM3 is larger than the third threshold (S84: equivalent to a determination unit). If the detection result is larger than the third threshold (S84: YES), the CPU 31 determines whether the relay RLY2 After storing that the relay contact is short-circuited in the RAM 33 (S85), the inverter 2 is turned off (step S92), and the processing of FIG.

  On the other hand, when the detection result by the detection unit VM3 is not greater than the third threshold (S84: NO), the CPU 31 turns on the relay RLY2 (S86) and waits for a predetermined time (S87). Further, after detecting the voltage on the power load 43 side by the detection unit VM3 (S88), the CPU 31 turns off the relay RLY2 (S89).

  Next, the CPU 31 determines whether or not the detection result by the detection unit VM3 is larger than the third threshold (S90: equivalent to a determination unit). If the detection result is larger than the third threshold (S90: YES), the CPU 31 determines whether the relay RLY1 The fact that the relay contact is short-circuited is stored in the RAM 33 (S91). The third threshold value may be different between steps S84 and S90. On the other hand, when the detection result is not greater than the third threshold (S90: NO), or when the process of step S91 is completed, the CPU 31 turns off the inverter 2 (step S92) and ends the process of FIG.

As described above, according to the third embodiment, one terminal pair at the relay contacts of the relays RLY1 and RLY2 is connected to both ends of the first winding N1a of the isolation transformer T1a, and the other terminal pair is It is cut off from the single-phase two-wire power system 4a. Then, the inverter 2 converts a DC voltage applied from the outside into an AC voltage and applies it to the second winding N2 of the isolation transformer T1a, and the detection unit VM3 has another terminal pair at each of the relay contacts RLY1 and RLY2 ( That is, the voltage between the terminal pair opposite to the first winding N1a side) is detected. In this state, the control unit 30 sequentially turns on and off one of the relays RLY1 and RLY2, and determines whether or not the voltage detected by the detection unit VM3 is greater than the third threshold value each time it is turned on.
Thereby, when one of the relays RLY1 and RLY2 is turned on, and the other relay contact is short-circuited, the detection unit VM3 is connected from the inverter 2 via the isolation transformer T1a and the relay contacts of the relays RLY1 and RLY2. When the other relay contact is not short-circuited, no voltage is applied to the detection unit VM3. Accordingly, when the voltage detected by the detection unit VM3 when the control unit 30 sequentially turns on one and the other of the relays RLY1 and RLY2 is larger than the third threshold, the relay contact of the relays RLY1 and RLY2 that is not turned on Can be determined to be short-circuited.

(Embodiment 4)
In the second embodiment, an AC voltage is applied from the power system 4a side to the relay contacts of relays RLY1, RLY2, and RLY3, whereas in the fourth embodiment, relays RLY1, RLY2, and RLY3 are each applied. An AC voltage is applied to the relay contact from the inverter 2 side via the insulation transformer T1b.
FIG. 10 is a block diagram illustrating a configuration example of the power conversion device according to the fourth embodiment of the present invention. In the figure, 1d is a power conversion device, and the power conversion device 1d includes a switching device 3d for turning on / off the connection between the inverter 2 and the output end on the AC side of the inverter 2 and the single-phase three-wire power system 4b. Is provided.

  The switch device 3d includes an isolation transformer T1b, relays RLY1 and RLY2 in which one terminal pair at each relay contact is connected to both ends of the first winding N1b of the isolation transformer T1b, and one terminal at the relay contact is the first. A relay RLY3 connected to the midpoint of the winding N1b and a control unit 30 are provided. Here, the other terminal pairs at the relay contacts of the relays RLY1 and RLY2 (that is, the terminal pairs opposite to the first winding N1b side) are the first terminal TM1 and the second terminal TM2, and the relay contacts of the relay RLY3 The other terminal (that is, the terminal opposite to the first winding N1b side) is the third terminal TM3.

  The switch device 3d also includes a first detector VM1 that detects a voltage between the first terminal TM1 and the third terminal TM3, and a second detector VM2 that detects a voltage between the second terminal TM2 and the third terminal TM3. Prepare. A power load 43 is connected between the first terminal TM1 and the second terminal TM2. A power load 41 is connected between the first terminal TM1 and the third terminal TM3. A power load 42 is connected between the second terminal TM2 and the third terminal TM3.

The switch device 3d may simply turn on / off the connection between the inverter 2 and the power loads 41, 42, and 43. The detection unit VM0 that detects the voltage of the second winding N2 of the insulating transformer T1b is not essential.
Since the other configuration of the power conversion device 1d is the same as that of the power conversion devices 1a and 1b in the first and second embodiments, portions corresponding to the first and second embodiments are denoted by the same reference numerals. Description is omitted. Hereinafter, the AC voltage output from the inverter 2 is referred to as a voltage Vc.

  In the above-described configuration, when the control unit 30 turns off the inverter 2 and the relays RLY1 to RLY3, a voltage is applied to each relay contact from the power system 4b to the relays RLY1 to RLY3 via the main breaker 40b. Confirm that the main breaker 40b is open. As a result, the possibility that the inverter 2 becomes a single operation is eliminated. Next, the control unit 30 turns on the inverter 2 to apply a voltage to one terminal at each relay contact from the relays RLY1 to RLY3, and then turns on the relay RLY3. Whether or not the relay contacts of the relays RLY1 and RLY2 are short-circuited is individually determined based on the voltages detected by the two detectors VM2 (that is, the voltages on the power loads 41 and 42 side).

  For example, when the relay contact of the relay RLY1 is short-circuited, a voltage of approximately Vc / 2 is applied from the inverter 2 to the first detector VM1 via the isolation transformer T1b and the relay contacts of the relays RLY1 and RLY3. . For this reason, when the voltage detected by the first detector VM1 is approximately Vc / 2, that is, when the voltage is larger than the fifth threshold, it is determined that the relay contact of the relay RLY1 is short-circuited. Similarly, when the voltage detected by the second detector VM2 is larger than the fifth threshold, it is determined that the relay contact of the relay RLY2 is short-circuited.

  Here, when the relay contacts of the relays RLY1 and RLY2 are both short-circuited, when the relay RLY3 is turned off, the inverter 2 passes through the isolation transformer T1b and the relay contacts of the relays RLY1 and RLY2. A voltage of approximately Vc is applied to the series circuit of the first detector VM1 and the second detector VM2. At this time, since a voltage of approximately Vc / 2 may be applied to each of the first detector VM1 and the second detector VM2, it is possible to determine whether or not the relay contact of the relay RLY3 is short-circuited. Can not.

  On the other hand, when it is determined that either one of the relay contacts of the relays RLY1 and RLY2 is short-circuited and the other is not short-circuited, the relay that is short-circuited when the control unit 30 turns the relay RLY3 from on to off. Based on the voltage detected by the detector corresponding to the contact, it is determined whether or not the relay contact of the relay RLY3 is short-circuited. For example, when the relay contact of the relay RLY1 is short-circuited and the voltage detected by the first detector VM1 when the relay RLY3 is turned off is approximately Vc / 2, the relay contact of the relay RLY3 is short-circuited. It is determined that

  Next, when it is determined that neither of the relay contacts of the relays RLY1 and RLY2 are short-circuited, the control unit 30 turns off the relay RLY3 and turns on one of the relays RLY1 and RLY2 and turns it on. When the voltage detected by the detector corresponding to this relay is larger than the sixth threshold, it is determined that the relay contact of the relay RLY3 is short-circuited. For example, when the relay RLY1 is turned on and the voltage detected by the first detector VM1 is approximately Vc / 2, it is determined that the relay contact of the relay RLY3 is short-circuited.

  In the above-described procedure, the control unit 30 turns on the inverter 2 and the relay RLY3 with the possibility that the relay contacts of each of the two or more relays are short-circuited, but before the relay RLY3 is turned on. Based on the detection results of the first detector VM1 and the second detector VM2, the control unit 30 may first determine whether or not the relay contacts of each of the two or more relays are short-circuited. In this case, the relay contact short circuit determination according to the detection results of the first detector VM1 and the second detector VM2 is as follows.

(E) When the detection result of the first detector VM1 is approximately Vc / 2 and the detection result of the second detector VM2 is approximately 0, it is determined that the relay contacts of the relays RLY1 and RLY3 are short-circuited. The
(F) When the detection result of the second detector VM2 is approximately Vc / 2 and the detection result of the first detector VM1 is approximately 0, it is determined that the relay contacts of the relays RLY2 and RLY3 are short-circuited. The
(G) When the sum of the detection results of the first detector VM1 and the second detector VM2 is substantially Vc, it is determined that at least the relay contacts of the relays RLY1 and RLY2 are short-circuited.

Below, operation | movement of the control part 30 mentioned above is demonstrated using the flowchart which shows it.
11 and 12 are flowcharts showing the processing procedure of the CPU 31 that determines whether or not the relay contact is short-circuited in the switch device 3d according to the fourth embodiment of the present invention. However, the determination processes from (e) to (g) described above are self-explanatory and will not be described with reference to flowcharts.

  Of the processes from steps S100 to S105 shown in FIG. 11, the processes except for steps S101 and S103 are substantially the same as the processes from steps S70 to S75 shown in FIG. 8 of the third embodiment. A part of the description is omitted.

  When the process of FIG. 11 is activated, the CPU 31 turns off the inverter 2 (S100), and turns off the relays RLY1 to RLY3 (S101). Thereafter, the CPU 31 waits for a predetermined time (S102), and then detects the voltage on the power loads 41 and 42 side by the first detector VM1 and the second detector VM2 (S103).

  Next, the CPU 31 determines whether or not there is voltage application from the power system 4b (S104). If there is voltage application (S104: YES), the CPU 31 performs processing in step S102 in order to wait until there is no voltage application. Move. When there is no voltage application from the power system 4b (S104: NO), the CPU 31 takes in the contact signal of the auxiliary contact of the main breaker 40b by the I / O 35 and determines whether the main breaker 40b is opened (S105). ), When it is not opened (S105: NO), it waits until it is opened.

  When the main breaker 40b is opened (S105: YES), the CPU 31 turns on the relay RLY3 by the relay drive circuit 36 (S106: equivalent to the second on means) and then turns on the inverter 2 (S107). It waits for a predetermined time longer than the operation time of RLY3 and the ON time of inverter 2 (S108).

  Moving to FIG. 12, the CPU 31 detects the voltages on the power loads 41 and 42 side by the first detector VM1 and the second detector VM2 (S110). Next, the CPU 31 determines whether or not the detection result of the detector VM1 is larger than the fifth threshold (S111: corresponding to the second determination means), and if it is larger than the fifth threshold (S111: YES), the relay The fact that the relay contact of RLY1 is short-circuited is stored in the RAM 33 (S112).

  When the detection result is not greater than the fifth threshold value in step S111 (S111: NO), or when the process of step S112 is completed, the CPU 31 determines whether or not the detection result of the second detector VM2 is greater than the fifth threshold value. (S113: Corresponding to the second determination means), if larger than the fifth threshold (S113: YES), the fact that the relay contact of the relay RLY2 is short-circuited is stored in the RAM 33 (S114). The fifth threshold value may be different between steps S111 and S113.

  When the detection result is not larger than the fifth threshold value in step S113 (S113: NO), or when the process of step S114 is completed, the CPU 31 determines that both of the relay contacts RLY1 and RLY2 are based on the storage contents of the RAM 33. It is determined whether or not they are short-circuited (S115). If both are short-circuited (S115: YES), the inverter 2 is turned off (S124), and the processing of FIG. This is a determination branch due to the inability to determine the short circuit of the relay contact of the relay RLY3.

  When at least one of the relay contacts of the relays RLY1 and RLY2 is not short-circuited (S115: NO), the CPU 31 turns off the relay RLY3 (S116). Thereafter, the CPU 31 determines whether one of the relay contacts of the relays RLY1 and RLY2 is short-circuited based on the stored contents of the RAM 33 (S117), and when neither is short-circuited (S117: NO). Then, the relay RLY1 or RLY2 is turned on by the relay drive circuit 36 (S118: equivalent to means for turning on).

  When any one of the relay contacts is short-circuited in step S117 (S117: YES) or when the process of step S118 is completed, the CPU 31 waits for a predetermined time longer than the respective operation time from the relays RLY1 to RLY3 (S119). ). Further, the CPU 31 detects the voltage on the power load 41 or 42 side by the first detector VM1 or the second detector VM2 (S120), and then turns off the relays RLY1 and RLY2 (S121).

  In said step S120, CPU31 detects the voltage of the detector corresponding to the relay which determined with the relay which turned on or the relay contact being short-circuited. For example, when the CPU 31 turns on the relay RLY1 in step S118, the CPU 31 detects the voltage on the power load 41 side by the first detector VM1. For example, if the CPU 31 determines in step S117 that the relay contact of the relay RLY2 is short-circuited, the CPU 31 detects the voltage on the power load 42 side using the second detector VM2.

  Next, the CPU 31 determines whether or not the detection result of the first detector VM1 or the second detector VM2 (here, the detection result in step S120) is larger than the sixth threshold (S122: equivalent to determination means). ), When larger than the sixth threshold (S122: YES), the fact that the relay contact of the relay RLY3 is short-circuited is stored in the RAM 33 (S123). On the other hand, when the detection result is not greater than the sixth threshold (S122: NO), or when the process of step S123 is completed, the CPU 31 turns off the inverter 2 (S124) and ends the process of FIG.

As described above, according to the fourth embodiment, one terminal pair at each relay contact of the relays RLY1 and RLY2 is connected to both ends of the first winding N1b of the isolation transformer T1b, and the first winding N1b. Is connected to one terminal of the relay contact of the relay RLY3, and the other terminal pair of the relay contacts of the relays RLY1 and RLY2 and the other terminal of the relay contact of the relay RLY3 are of a single-phase three-wire type. It is cut off from the power system 4b. Then, the inverter 2 converts a DC voltage applied from the outside into an AC voltage and applies it to the second winding N2 of the isolation transformer T1b, and the other terminal pair (that is, the side opposite to the first winding N1b side). The voltage between the first terminal TM1 and the second terminal TM2 in the terminal pair) and the other terminal (that is, the terminal opposite to the first winding N1b side) is the first detector VM1 and the second voltage. The detector VM2 detects it. In this state, the control unit 30 turns on the relay RLY3 and determines whether or not the voltages detected by the first detector VM1 and the second detector VM2 when the relay RLY3 is turned on are larger than the fifth threshold value.
Thereby, when the relay RLY3 is turned on, when the switch including the first terminal TM1 (or the second terminal TM2) among the relay contacts of the relays RLY1 and RLY2 is short-circuited, the insulation transformer T1b is connected from the inverter 2. Vc / 2 is applied to the first detector VM1 (or the second detector VM2) via the relay contact of the relay RLY3 and the shorted relay contact, while the relays RLY1 and RLY2 When none of the relay contacts is short-circuited, no voltage is applied to the first detector VM1 and the second detector VM2.
Therefore, when the voltage detected by the first detector VM1 (or the second detector VM2) when the control unit 30 turns on the relay RLY3 is larger than the fifth threshold, the first relay contact of the relays RLY1 and RLY2 It can be determined that the relay contact including the one terminal TM1 (or the second terminal TM2) is short-circuited.

According to the fourth embodiment, when the voltage detected by each of the first detector VM1 and the second detector VM2 when the control unit 30 turns on the relay RLY3 is not greater than the fifth threshold, the relay It is determined that none of the relay contacts of RLY1 and RLY2 are short-circuited. As a result of the determination, when the control unit 30 turns on the relay including the first terminal TM1 in the relay contact of the relays RLY1 and RLY2, or the first terminal TM1 of the relay contacts of the relays RLY1 and RLY2. When the relay contact including the short circuit is short-circuited, the control unit 30 determines whether or not the voltage detected by the first detector VM1 is greater than the sixth threshold value. Separately, when the control unit 30 turns on a relay including the second terminal TM2 in the relay contact, or when the relay contact including the second terminal TM2 is short-circuited among the relay contacts of the relays RLY1 and RLY2. The control unit 30 determines whether or not the voltage detected by the second detector VM2 is larger than the sixth threshold value.
Thereby, when the relay including the first terminal TM1 (or the second terminal TM2) is turned on, or when the relay contact including the first terminal TM1 (or the second terminal TM2) is short-circuited. In addition, when the relay contact of the relay RLY3 is short-circuited, the inverter 2 passes through the isolation transformer T1b, and further includes the relay contact including the first terminal TM1 (or the second terminal TM2) and the relay contact of the relay RLY3. When the voltage Vc / 2 is applied to the first detector VM1 (or the second detector VM2) while the relay contact of the relay RLY3 is not short-circuited, the first detector VM1 (or the second detector) No voltage is applied to VM2).
Therefore, when the control unit 30 turns on the relay including the first terminal TM1 (or the second terminal TM2) in the relay contact, or the relay contact including the first terminal TM1 (or the second terminal TM2) is short-circuited. In this case, when the voltage detected by the first detector VM1 (or the second detector VM2) is larger than the sixth threshold, it can be determined that the relay contact of the relay RLY3 is short-circuited.

  The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. In addition, the technical features described in each embodiment can be combined with each other.

1a, 1b, 1c, 1d Power converter 2 Inverter 3a, 3b, 3c, 3d Switch device 30 Control unit 31 CPU
32 ROM
33 RAM
34 Inverter drive circuit 36 Relay drive circuit 37 A / D converter T1a, T1b Insulation transformer N1a, N1b First winding N2 Second winding RLY1, RLY2, RLY3 Relay TM1 First terminal TM2 Second terminal VM0, VM3 Detector VM1 1st detector VM2 2nd detector 4a, 4b Electric power system 40a, 40b Main circuit breaker 41, 42, 43 Electric power load

Claims (10)

A transformer to which an AC voltage is applied from the power system, a pair of switches for disconnecting the first winding of the transformer from the power system, and a controller for controlling on and off of each of the pair of switches In a switch device comprising:
A detector for detecting the voltage of the second winding of the transformer;
The controller is
An ON means for alternately turning on the pair of switches sequentially;
And a means for determining whether or not the voltage detected by the detection unit is greater than a predetermined threshold each time the ON means is turned ON. The power system is a single-phase three-wire system,
The first winding has a midpoint;
A second switch for disconnecting the midpoint from the neutral line of the power system;
The control unit includes a determination unit that determines whether or not the voltage detected by the detection unit is smaller than a second threshold,
The switch device according to claim 1, wherein the turning-on means is turned on when it is judged that the judging means is small. A power converter comprising: the switch device according to claim 1; and a voltage converter that converts an externally applied DC voltage into an AC voltage and applies the AC voltage to the second winding,
A second detection unit that detects a voltage between a pair of terminals opposite to the first winding side in the pair of switches;
The said control part has a means to determine whether the voltage which the said 2nd detection part detected is larger than a 3rd threshold value whenever the said ON means turns on. The power converter device characterized by the above-mentioned. A power converter comprising: the switch device according to claim 2; and a voltage converter that converts an externally applied DC voltage into an AC voltage and applies the AC voltage to the second winding,
The voltage between the first and second terminals of the pair of terminals opposite to the first winding side in the pair of switches and the terminal on the opposite side to the middle point side in the second switch. Comprising first and second detectors for detecting
The controller is
Second on means for turning on the second switch;
And second determination means for determining whether or not the voltage detected by each of the first and second detectors is greater than a fifth threshold when the second ON means is turned ON. Power conversion device. The controller is
Means for turning on the switch including the first or second terminal when the second determination means determines that no voltage is greater than the fifth threshold;
When the means is turned on, or when the second determination means determines that any voltage is greater than the fifth threshold, the voltage detected by the first or second detector is greater than the sixth threshold. The power conversion device according to claim 4, further comprising: a unit that determines whether the size is large. A transformer, a pair of switches having one terminal pair connected to both ends of the first winding of the transformer, a control unit for controlling on and off of each of the pair of switches, and a direct current applied from the outside In a power converter comprising: a voltage converter that converts a voltage into an AC voltage and applies the voltage to the second winding of the transformer;
A second detector for detecting a voltage between the other terminal pairs in the pair of switches;
The controller is
An ON means for alternately turning on the pair of switches sequentially;
And a means for determining whether or not the voltage detected by the second detection unit is greater than a third threshold each time the ON means is turned ON. A transformer, a pair of switches having one terminal pair connected to both ends of the first winding of the transformer, and a second switch having one terminal connected to the midpoint of the first winding; A control unit for controlling on and off of each of the pair of switches and the second switch; a voltage converter for converting a DC voltage applied from the outside into an AC voltage and applying the AC voltage to the second winding of the transformer; In a power converter comprising:
A first and a second detector for detecting a voltage between each of the first and second terminals of the other terminal pair in the pair of switches and the other terminal in the second switch;
The controller is
Second on means for turning on the second switch;
Second determination means for determining whether or not the voltage detected by each of the first and second detectors is greater than a fifth threshold when the second ON means is ON;
Means for turning on the switch including the first or second terminal when the second determination means determines that no voltage is greater than the fifth threshold;
When the means is turned on, or when the second determination means determines that any voltage is greater than the fifth threshold, the voltage detected by the first or second detector is greater than the sixth threshold. And a means for determining whether or not the power is large. A transformer to which a single-phase two-wire AC voltage is applied from the power system, a pair of switches for disconnecting the first winding of the transformer from the power system, and turning on and off each of the pair of switches In a method of detecting a short circuit of each of the switches in a switch device comprising a control unit for controlling off,
Prepare a detection unit for detecting the voltage of the second winding of the transformer,
Alternately turn on the pair of switches sequentially,
Each time it is turned on, the voltage detected by the detection unit and a predetermined threshold value are compared,
Based on the comparison result, it is determined whether or not one of the pair of switches that is not turned on is short-circuited. A transformer to which a single-phase three-wire AC voltage is applied from the power system, a pair of switches for disconnecting both ends and a middle point of the first winding of the transformer from the power system, and a second switch In a method of detecting a short circuit of each of the pair of switches and the second switch in a switch device comprising a switch and a control unit that controls on and off of each of the pair of switches and the second switch,
Prepare a detection unit for detecting the voltage of the second winding of the transformer,
Determining whether the voltage detected by the detection unit is smaller than a second threshold;
If it is determined to be small, the pair of switches are alternately turned on sequentially,
Each time it is turned on, the voltage detected by the detection unit and a predetermined threshold value are compared,
Based on a comparison result, it is determined whether the switch that is not turned on or the second switch of the pair of switches is short-circuited. A transformer, a pair of switches having one terminal pair connected to both ends of the first winding of the transformer, and a second switch having one terminal connected to the midpoint of the first winding; A control unit for controlling on and off of each of the pair of switches and the second switch; a voltage converter for converting a DC voltage applied from the outside into an AC voltage and applying the AC voltage to the second winding of the transformer; In a method for detecting a short circuit of each of the pair of switches and the second switch in a power conversion device comprising:
First and second detectors for detecting a voltage between each of the first and second terminals of the other pair of switches in the pair of switches and the other terminal of the second switch are prepared,
Turn on the second switch;
Comparing the voltage detected by each of the first and second detectors with a fifth threshold;
Based on the comparison result, it is determined whether each of the pair of switches is short-circuited,
If none of the pair of switches are short-circuited, turn on the switch including the first or second terminal,
When the switch is turned on, or when any of the voltages detected by the first and second detectors is greater than the fifth threshold, the voltage detected by the first or second detector and the sixth Compare thresholds,
It is determined whether or not the second switch is short-circuited based on the comparison result.

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