Semiconductor breaker and power distribution system

Abstract

A semiconductor breaker (4) comprises: two semiconductor elements (50a, 50b) that are connected in series and break currents in different directions; two diodes (51a, 51b) that are connected in parallel to the respective semiconductor elements (50a, 50b); a current limiting circuit (53) that is connected in parallel to the semiconductor elements (50a, 50b); and a control device (6) that controls the semiconductor elements (50a, 50b). The control device (6) has set therefor a first delay time (T1) and a switching frequency at which the two semiconductor elements (50a, 50b) are turned on and off in an alternating pattern, and, until the first delay time (T1) elapses after the semiconductor breaker (4) is powered on, increases the switching frequency at a preset increase rate, and turns on and off the semiconductor elements (50a, 50b) on the basis of the switching frequency.

Description

Semiconductor circuit breakers and power distribution systems

[0001] The present disclosure relates to semiconductor circuit breakers and power distribution systems.

[0002] Solid-state circuit breakers (SSCBs) have been known in the past for use in power distribution systems that distribute power from a power source to load devices. The SSCB interrupts current when a short circuit occurs in the load device. The SSCB has a semiconductor element that controls the conduction and interruption of current in the circuit. The semiconductor element can be turned on or off at any timing by controlling the gate voltage input to the semiconductor element. For example, the semiconductor circuit breaker disclosed in Patent Document 1 measures the input and output voltages when interrupting current, and controls the timing of turning the semiconductor element on or off based on the measured voltage, thereby reducing switching surges.

[0003] Electrical power distribution systems often connect motors as loads. The main types of motors are induction motors and synchronous motors. When an induction motor is connected to a constant-frequency, constant-voltage AC power source and started, its rotation speed rapidly increases to near its rated frequency. For example, an induction motor driving a conveyor belt on a factory production line may cause the belt to rapidly increase to its rated speed upon start-up, potentially causing parts on the conveyor belt to tip over due to the resulting acceleration. Therefore, when an induction motor is used as a load, an inverter is required to gradually increase the motor's rotation speed from zero to near its rated speed when power is supplied to the induction motor. Synchronous motors cannot be started by directly connecting them to a constant-frequency AC power source. Starting a synchronous motor requires a control system that gradually increases the power supply frequency while synchronizing the power supply frequency with the rotation speed. Therefore, when a synchronous motor is used as a load, an inverter is installed to control the start-up of the synchronous motor.

[0004] JP 2016-115528 A

[0005] However, inverters are expensive. Therefore, including an inverter increases the manufacturing cost of a power distribution system. Therefore, if a semiconductor circuit breaker does not require an inverter, the manufacturing cost of the power distribution system can be reduced. When using the semiconductor circuit breaker disclosed in Patent Document 1, it is necessary to control the start of the motor using an inverter.

[0006] The present disclosure has been made in view of the above, and has an object to provide a semiconductor circuit breaker that can control the start-up of a load device without using an inverter.

[0007] In order to solve the above-mentioned problems and achieve the object, the semiconductor circuit breaker according to the present disclosure is a semiconductor circuit breaker provided in an electric path connecting a power source and a load device, and includes two semiconductor elements connected in series with currents to be interrupted in different directions, two diodes connected in parallel to each semiconductor element, a current limiting circuit connected in parallel to the semiconductor elements, and a control device that controls the semiconductor elements. The control device is set with a first delay time and a switching frequency at which the two semiconductor elements alternately switch on and off, and increases the switching frequency at a preset increase rate until the first delay time has elapsed after the semiconductor circuit breaker is closed, and turns the semiconductor elements on and off based on the switching frequency.

[0008] The semiconductor circuit breaker according to the present disclosure has the advantage that it is possible to control the start-up of a load device without using an inverter.

[0009] a flow chart of a control device included in the semiconductor circuit breaker according to the first embodiment; a graph schematically showing a control signal in the control mode shown in FIG. 4 and a waveform of a voltage supplied to the load device by the single-phase breaking module; a graph schematically showing a control signal in the control mode and a voltage supplied to the load device by the semiconductor circuit breaker according to the second embodiment; an explanatory diagram schematically showing an electrical connection state between a power source, a semiconductor circuit breaker, and a load device in a power distribution system according to a third embodiment; a configuration diagram schematically showing a single-phase breaking module and a current compensation circuit included in the semiconductor circuit breaker according to the third embodiment;

[0010] Hereinafter, a semiconductor circuit breaker and a power distribution system according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0011] First Embodiment. Fig. 1 is a schematic diagram illustrating the overall configuration of a power distribution system according to a first embodiment. As shown in Fig. 1, the power distribution system 100 according to the first embodiment includes a power source 1, a load device 2, a circuit breaker (CB) 3, and a semiconductor circuit breaker 4. The power source 1 is a three-phase AC power source. As shown in Fig. 1, the circuit breaker 3 and the semiconductor circuit breaker 4 are incorporated inside a control panel 10 that connects the power source 1 and the load device 2. The power source 1 supplies three-phase AC power to the load device 2 via the control panel 10. The load device 2 is connected to the power source 1 via the control panel 10. The load device 2 is, for example, an induction motor or a synchronous motor. The load device 2 rotates due to a rotating magnetic field generated by the three-phase AC current.

[0012] A power source 1 is connected to the circuit breaker 3. In the event of a short-circuit fault, the circuit breaker 3 interrupts the fault current flowing in the power circuit between the power source 1 and the load device 2. A semiconductor circuit breaker 4 is provided for each load device 2. In the example shown in Fig. 1, four load devices 2 are shown, but the number of load devices 2 may be one or more, and the number of load devices 2 is not limited to the example shown in Fig. 1. Each semiconductor circuit breaker 4 is provided on an electric path branching from the circuit breaker 3, and is connected to the corresponding load device 2 via the branched electric path.

[0013] 2 is an explanatory diagram showing the electrical connection state between the power source, the semiconductor circuit breaker, and the load device in the power distribution system according to the first embodiment. As shown in FIG. 2, the semiconductor circuit breaker 4 includes three single-phase interrupting modules 5 corresponding to the respective phases of the power, and a control device 6. The semiconductor circuit breaker 4 can individually interrupt the current of each phase using the single-phase interrupting modules 5.

[0014] 3 is a configuration diagram schematically illustrating a single-phase breaking module included in the semiconductor circuit breaker according to the first embodiment. The single-phase breaking module 5 includes two semiconductor elements 50a, 50b, two diodes 51a, 51b, a disconnection switch 52, a current limiting circuit 53, a current meter 54, and a current measurement circuit 55. In the single-phase breaking module 5, for example, in FIG. 3, the leftmost terminal is connected to the power source 1, and the rightmost terminal is connected to the load device 2.

[0015] Each of the two semiconductor elements 50a, 50b is capable of interrupting current in a single direction. The single-phase interrupting module 5 is capable of interrupting current in both directions by connecting the semiconductor element 50a and the semiconductor element 50b in series in opposite directions. The semiconductor elements 50a, 50b may be, for example, insulated gate bipolar transistors (IGBTs) or metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0016] The diode 51a is connected in parallel to the semiconductor element 50a. The diode 51b is connected in parallel to the semiconductor element 50b. The diodes 51a and 51b bypass current in a direction that the semiconductor elements 50a and 50b cannot interrupt. In the case shown in FIG. 3 , for example, when current flows from left to right, the current flows through the diode 51a and the semiconductor element 50b, and the current can be interrupted by turning off the semiconductor element 50b. On the other hand, in the case shown in FIG. 3 , when current flows from right to left, the current flows through the diode 51b and the semiconductor element 50a, and the current can be interrupted by turning off the semiconductor element 50a. The disconnecting switch 52 is composed of mechanical contacts. The single-phase disconnecting module 5 can mechanically disconnect the power circuit by turning off the disconnecting switch 52 after turning off the two semiconductor elements 50a and 50b.

[0017] The current limiting circuit 53 is connected in parallel to the semiconductor elements 50a and 50b. The current limiting circuit 53 includes a nonlinear element 53a, a resistive element 53b, and a switch 53c. The nonlinear element 53a has a nonlinear current-voltage characteristic. The nonlinear element 53a functions as a current limiting element that reduces the current flowing through the power circuit. For example, a Zener diode or a varistor is used as the nonlinear element 53a.

[0018] When interrupting the current flowing through the single-phase interrupting module 5, turning off the semiconductor element 50a or the semiconductor element 50b commutates the current to the current limiting circuit 53. When the switch 53c is on, the current commutated to the current limiting circuit 53 flows through the path that passes through the switch 53c and the resistor element 53b, and is limited by the voltage drop across the resistor element 53b. When the switch 53c is then turned off, the current flows through the path that passes through the nonlinear element 53a, and is limited by the voltage drop across the nonlinear element 53a, reaching zero and being interrupted. When the fault current to be interrupted in the single-phase interrupting module 5 is large, the energy stored in the power circuit may exceed the energy tolerance of the nonlinear element 53a. Therefore, the current is first passed through the resistor element 53b, which absorbs a certain amount of energy. Then, turning off the switch 53c commutates the current to the nonlinear element 53a, making it possible to interrupt the fault current using the nonlinear element 53a, which is less expensive and has a lower energy tolerance than the resistor element 53b.

[0019] The current meter 54 measures the current on the load device 2 side of the single-phase breaking module 5. The current meter 54 is, for example, a shunt resistor or a current transformer (CT). The current meter 54 is connected to a current measurement circuit 55. The current measurement circuit 55 transmits a current signal s1 to the control device 6 based on the measurement value of the current meter 54.

[0020] The control device 6 receives a current signal s1 from the current measurement circuit 55 and transmits a control command s2 to the gate control circuit 56. The gate control circuit 56 controls the gate voltages of the semiconductor elements 50a and 50b based on the control command s2 from the control device 6. This causes the control device 6 to turn the semiconductor elements 50a and 50b on and off. The control device 6 also has a first delay time T1, which is the time it takes to enter the control mode after the semiconductor circuit breaker 4 is closed, and a switching frequency at which the two semiconductor elements 50a and 50b are alternately turned on and off. The first delay time T1 may be predetermined or variable, for example.

[0021] 4 is a flowchart of the control device included in the semiconductor circuit breaker according to the first embodiment. When an ON command is input to the semiconductor circuit breaker 4, the semiconductor circuit breaker 4 is turned on, and power supply from the power source 1 to the load device 2 begins (step S101). The control device 6 then begins the control mode (step S102). The control mode is responsible for starting the load device 2. In the control mode, the voltage and current supplied from the semiconductor circuit breaker 4 to the load device 2 are controlled so that the rotation speed of the load device 2 increases to near the rated rotation speed during the period from when the power supply from the power source 1 begins to the load device 2 until the first delay time T1 has elapsed. The switch 53c of the current limiting circuit 53 remains off until the control mode ends.

[0022] After the first delay time T1 has elapsed, the control device 6 terminates the control mode (step S103), sends an ON command to the switch 53c of the current limiting circuit 53 (step S104), and transitions the semiconductor circuit breaker 4 to a steady-state ON state (step S105). During the control mode, the semiconductor elements 50a and 50b are repeatedly turned ON and OFF. As a result, the current flowing through the semiconductor circuit breaker 4 does not exceed the rated current of the semiconductor circuit breaker 4, and the energy stored in the power circuit is small. Therefore, if a short-circuit accident or the like occurs during the control mode, it is not necessary to absorb energy using the resistive element 53b when turning off the semiconductor elements 50a and 50b. Instead, the current is directly diverted to the nonlinear element 53a and interrupted. After the control mode terminates and the semiconductor circuit breaker 4 transitions to a steady-state ON state, the switch 53c of the current limiting circuit 53 is kept ON. As a result, even if a short circuit occurs in the power circuit, causing a large fault current to flow and increasing the amount of energy stored in the power circuit, when the semiconductor elements 50a and 50b are turned off, the semiconductor circuit breaker 4 first limits the current and absorbs the energy using the resistance element 53b, and then diverts the current to the nonlinear element 53a to limit and cut off the current, thereby being able to cut off even large fault currents.

[0023] Next, the control device 6 determines whether or not an OFF command for the semiconductor circuit breaker 4 has been received (step S106). If the control device 6 determines that an OFF command for the semiconductor circuit breaker 4 has not been received (step S106: No), the control device 6 continues the steady ON state of the semiconductor circuit breaker 4 and repeats step S106. On the other hand, if the control device 6 determines that an OFF command for the semiconductor circuit breaker 4 has been received (step S106: Yes), the control device 6 transmits an OFF command to the switch 53c of the current limiting circuit 53 (step S107). Then, the control device 6 transmits OFF commands to the semiconductor elements 50a and 50b (step S108) to interrupt the current. At this time, a certain time elapses between the transmission of the OFF command to the switch 53c and the completion of the OFF operation of the switch 53c. The control device 6 is set with a second delay time T2 that is longer than the certain time required for the operation from the transmission of the OFF command to the switch 53c to the completion of the OFF operation of the switch 53c. After the switch 53c has been turned off, the control device 6 transmits an OFF command to the semiconductor elements 50a and 50b after the second delay time T2 has elapsed so that the semiconductor elements 50a and 50b turn off. Finally, the semiconductor circuit breaker 4 is turned off and opened (step S109).

[0024] The reason why the OFF command is sent to the semiconductor elements 50a and 50b after the second delay time T2 has elapsed is to prevent wear on the electrical contacts of the switch 53c. If the semiconductor elements 50a and 50b are turned off before the OFF operation of the switch 53c is completed, the switch 53c will be turned off while current is still flowing through it, causing an arc discharge at the electrical contacts of the switch 53c and resulting in wear on the electrical contacts. On the other hand, if the OFF operation of the switch 53c is completed while the semiconductor elements 50a and 50b are in the ON state and the semiconductor elements 50a and 50b then perform the OFF operation, the current flowing through the switch 53c will be zero when the switch 53c is turned off. This prevents an arc from occurring at the electrical contacts of the switch 53c and prevents wear on the electrical contacts, making it possible to use, for example, an inexpensive mechanical switch.

[0025] Fig. 5 is a graph schematically showing the waveform of the control signal and the voltage supplied to the load device by the single-phase breaking module in the control mode shown in Fig. 4. The solid line shown in Fig. 5 is the power supply voltage supplied to the load device 2 by the single-phase breaking module 5. The dashed line shown in Fig. 5 is the control signal. The vertical axis of Fig. 5 represents voltage. The horizontal axis of Fig. 5 represents time.

[0026] As shown in FIG. 5 , the voltage supplied from the power supply 1 to the semiconductor circuit breaker 4 is an AC voltage with a power supply frequency fa (with a period Ta = 1 / fa). The power supply frequency fa is, for example, 50 Hz or 60 Hz. The control signal is a rectangular wave with a frequency fb (with a period Tb = 1 / fb), where fb < fa (Tb > Ta). Here, the frequency fb is a switching frequency at which the semiconductor elements 50a and 50b alternate between an on state and an off state. The control signal controls the gate voltages of the semiconductor elements 50a and 50b, and alternates between a state in which the semiconductor element 50a is off and the semiconductor element 50b is on and a state in which the semiconductor element 50a is on and the semiconductor element 50b is off every half period (Tb / 2).

[0027] When semiconductor element 50a is in the off state and semiconductor element 50b is in the on state, the waveform of the voltage supplied by single-phase breaking module 5 to load device 2 is only a half-wave of the AC power supply voltage waveform with power supply frequency fa, which is a positive voltage. Conversely, when semiconductor element 50a is in the on state and semiconductor element 50b is in the off state, the waveform of the voltage supplied by single-phase breaking module 5 to load device 2 is only a half-wave of the AC power supply voltage waveform with power supply frequency fa, which is a negative voltage. As a result, the voltage supplied by single-phase breaking module 5 to load device 2 has a waveform whose envelope is the control signal shown by the dashed line, and whose envelope contains multiple half-waves of the AC power supply voltage waveform, resulting in a low-frequency voltage waveform whose main frequency component is the frequency fb of the control signal.

[0028] That is, the control device 6 performs control to alternate, at the switching frequency, an operation of turning on one semiconductor element 50b and turning off the other semiconductor element 50a when the voltage supplied to the load device 2 is positive, and an operation of turning off one semiconductor element 50b and turning on the other semiconductor element 50a when the voltage supplied to the load device 2 is negative. In this way, by controlling the on and off states of the semiconductor elements 50a and 50b based on the control signal of frequency fb, it is possible to supply a voltage waveform with a frequency lower than the power supply frequency fa to the load device 2.

[0029] The control device 6 may control the timing of switching on and off the semiconductor elements 50a and 50b using the monitoring result of whether the voltage supplied from the power supply 1 is positive or negative. In this case, based on the switching frequency, switching is performed between a first state in which one semiconductor element 50b is on when the voltage supplied from the power supply 1 is positive and the other semiconductor element 50a is off when the voltage supplied from the power supply 1 is negative, and a second state in which one semiconductor element 50b is off when the voltage supplied from the power supply 1 is positive and the other semiconductor element 50a is on when the voltage supplied from the power supply 1 is negative.

[0030] The above-described control is performed for each of the three single-phase breaking modules 5 corresponding to three-phase AC. Specifically, a control signal in which the V phase is shifted by 120° and the W phase is shifted by 240° relative to the U phase is input to the semiconductor element 50a and the semiconductor element 50b of each phase. As a result, the waveform of the voltage supplied from the semiconductor circuit breaker 4 to the load device 2 becomes a three-phase AC voltage with a frequency fb. The load device 2 rotates at a rotation speed corresponding to the frequency of the AC voltage supplied from the semiconductor circuit breaker 4. In the control mode, the frequency fb of the control signal is controlled to gradually increase from zero to the power supply frequency fa at a preset increasing rate, and the rotation speed of the load device 2 is gradually increased from zero to near the rated rotation speed.

[0031] As described above, the semiconductor circuit breaker 4 according to the first embodiment includes two semiconductor elements 50a, 50b connected in series and interrupting currents in different directions, two diodes 51a, 51b connected in parallel to each of the semiconductor elements 50a, 50b, a current limiting circuit 53 connected in parallel to the semiconductor elements 50a, 50b, and a control device 6 that controls the semiconductor elements 50a, 50b. The control device 6 is configured to set a first delay time T1 and a switching frequency at which the two semiconductor elements 50a, 50b are alternately turned on and off. The control device 6 increases the switching frequency at a predetermined rate from when the semiconductor circuit breaker 4 is turned on until the first delay time T1 has elapsed, and turns the semiconductor elements 50a, 50b on and off based on the switching frequency. Therefore, the semiconductor circuit breaker 4 according to the first embodiment can gradually increase the rotation speed of the load device 2 without using an inverter, thereby controlling the start of the load device 2. For example, if the load device 2 is an induction motor, gradually increasing the rotation speed of the load device 2 reduces the acceleration of the belt conveyor to which the load device 2 is connected at startup, thereby preventing parts on the belt conveyor from tipping over, etc. Also, if the load device 2 is a synchronous motor, it can be started without using an inverter.

[0032] Second Embodiment Next, a semiconductor circuit breaker 4 according to a second embodiment will be described. Fig. 6 is a graph schematically showing a control signal in a control mode and a power supply voltage supplied by the semiconductor circuit breaker to a load device for the semiconductor circuit breaker according to the second embodiment. The solid line shown in Fig. 6 is the power supply voltage supplied by the semiconductor circuit breaker 4 to the load device 2. The dashed line shown in Fig. 6 is the control signal. The vertical axis of Fig. 6 represents voltage. The horizontal axis of Fig. 6 represents time.

[0033] As shown in FIG. 6 , in the semiconductor circuit breaker 4 according to the second embodiment, the control signal transmitted from the control device 6 to the single-phase breaking module 5 is a signal that turns on the semiconductor elements 50a and 50b for the on-state time Ton within the frequency fc. As a result, the proportion of time that the semiconductor elements 50a and 50b are in the on-state within the period Ta of the power supply 1 shown in FIG. 5 is Ton / Tc, and the time average value of the voltage supplied by the single-phase breaking module 5 to the load device 2 can be reduced in accordance with the ratio of the time Ton to the period Tc. Ton / Tc is referred to as the duty ratio. In other words, by controlling the time that the semiconductor elements 50a and 50b are on within the period Tb of the control signal shown in FIG. 5 using the duty ratio Ton / Tc as shown in FIG. 6 , the frequency and effective value of the voltage supplied by the single-phase breaking module 5 to the load device 2 can be controlled.

[0034] As described above, the semiconductor circuit breaker 4 according to the second embodiment controls the single-phase breaking modules 5 of each phase by turning on and off the semiconductor elements 50a and 50b based on the switching frequency until the first delay time T1 has elapsed, and by alternately turning on the two semiconductor elements 50a and 50b based on the duty ratio within the period of the switching frequency. Furthermore, the control device 6 controls the frequency fb of the control signal to increase from zero to the power supply frequency fa at a predetermined rate, and gradually increases the duty ratio at a predetermined rate in accordance with this rate. Therefore, when starting the load device 2, the semiconductor circuit breaker 4 can gradually increase the voltage and frequency supplied to the load device 2. This allows the rotation speed of the motor, which is the load device 2, to increase more gradually.

[0035] Third Embodiment Next, a semiconductor circuit breaker 4A according to a third embodiment will be described. Fig. 7 is an explanatory diagram showing a power distribution system according to the third embodiment, which diagrammatically illustrates an electrical connection state between a power source, a semiconductor circuit breaker, and a load device.

[0036] The semiconductor circuit breaker 4A according to the third embodiment is characterized in that it includes a current compensation circuit 7 in addition to the configuration of the semiconductor circuit breaker 4 according to the first embodiment. The current compensation circuit 7 is connected between each phase of the single-phase breaking module 5.

[0037] 8 is a configuration diagram schematically showing a single-phase breaking module and a current compensation circuit included in a semiconductor circuit breaker according to a third embodiment. In the single-phase breaking module 5, for example, in FIG. 8, the leftmost terminal is connected to the power source 1, and the rightmost terminal is connected to the load device 2. The current compensation circuit 7 has a capacitor 70 and two semiconductor switches 71 and 72. The capacitor 70 and the two semiconductor switches 71 and 72 are connected in series. For example, in FIG. 8, the lowermost terminal of the current compensation circuit 7 is connected to the single-phase breaking module 5 of the adjacent phase.

[0038] Each of the semiconductor switches 71 and 72 is configured with a semiconductor element and a diode connected in parallel. Each of the two semiconductor elements is capable of blocking current in a single direction. The current compensation circuit 7 is capable of blocking current in both directions by connecting one semiconductor element and the other semiconductor element in series in the opposite directions. The diode is connected in parallel to the semiconductor element. The diode bypasses current in a direction that the semiconductor element cannot block.

[0039] Next, the operation of the current compensation circuit 7 will be described with reference to Fig. 9. Fig. 9 is a graph schematically showing the control signal in the control mode and the voltage supplied to the load device by the semiconductor circuit breaker according to the third embodiment. The solid line shown in Fig. 9 is the power supply voltage supplied to the load device 2 by the semiconductor circuit breaker 4. The dashed line shown in Fig. 9 is the control signal. The vertical axis of Fig. 9 represents voltage. The horizontal axis of Fig. 9 represents time.

[0040] In the semiconductor circuit breaker 4A according to the third embodiment, when a control signal indicated by a dashed line is applied, the single-phase breaking module 5 is turned on when the control signal is positive and the power supply voltage supplied to the single-phase breaking module 5 by the power supply 1 is positive. The single-phase breaking module 5 is turned on when the control signal is negative and the power supply voltage supplied to the single-phase breaking module 5 by the power supply 1 is negative. Therefore, in FIG. 9 , the single-phase breaking module 5 supplies the voltage from the power supply 1 to the load device 2 during time Te1 when the control signal is positive and the power supply voltage is positive and time Te2 when the control signal is negative and the power supply voltage is negative. On the other hand, the single-phase breaking module 5 does not supply the voltage from the power supply 1 to the load device 2 during times when the polarity of the control signal and the polarity of the power supply voltage are different, i.e., during time Td1 when the control signal is positive and the power supply voltage is negative and time Td2 when the control signal is negative and the power supply voltage is positive.

[0041] At times Te1 and Te2, the control device 6 controls the semiconductor switches 71 and 72 of the current compensation circuit 7 to charge the capacitor 70. Then, at times Td1 and Td2, the control device 6 controls the semiconductor switches 71 and 72 of the current compensation circuit 7 to discharge the capacitor 70 and supply voltage to the load device 2. In the semiconductor circuit breaker 4A according to the third embodiment, by controlling the current compensation circuit 7 in this manner, it is possible to increase the effective value of the voltage supplied to the load device 2, and it becomes possible to start the load device 2 even when the load on the load device 2 is large.

[0042] Next, a hardware configuration for realizing the control device 6 according to the present embodiment will be described. The control device 6 is realized by a processing circuit. The processing circuit may be a circuit in which a processor executes software, or may be a dedicated circuit.

[0043] When the processing circuit is realized by software, the processing circuit is, for example, a control circuit 80 shown in Fig. 10. Fig. 10 is an explanatory diagram showing a configuration example of the control circuit according to the first to third embodiments. The control circuit 80 includes an input unit 81, a processor 82, a memory 83, and an output unit 84. The input unit 81 is an interface circuit that receives data input from outside the control circuit 80 and provides the data to the processor 82. The output unit 84 is an interface circuit that sends data from the processor 82 or the memory 83 to outside the control circuit 80.

[0044] The processor 82 is a CPU (Central Processing Unit). The processor 82 may be a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor). The memory 83 may be, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable Programmable Read Only Memory), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD (Digital Versatile Disc).

[0045] 10 shows an example of hardware in which the functions of the control device 6 are realized by a general-purpose processor 82 and memory 83, but the functions of the control device 6 may also be realized by a dedicated hardware circuit. Fig. 11 is an explanatory diagram showing an example of the configuration of a dedicated hardware circuit according to the first to third embodiments.

[0046] 11 , the dedicated hardware circuit 85 includes an input unit 81, an output unit 84, and a processing circuit 86. The processing circuit 86 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The control device 6 may be realized by the processing circuit 86 for each function, or the functions of the control device 6 may be realized collectively by the processing circuit 86. The control device 6 may also be realized by combining the control circuit 80 and the hardware circuit 85.

[0047] The configurations shown in the above embodiments are examples of the contents of the present disclosure. The configurations of each embodiment can be combined with other known technologies. The configurations of each embodiment can also be combined as appropriate. Part of the configuration of each embodiment can be omitted or modified without departing from the gist of the present disclosure.

[0048] 1 Power supply, 2 Load equipment, 3 Circuit breaker, 4, 4A semiconductor circuit breaker, 5 Single-phase breaking module, 6 Control device, 7 Current compensation circuit, 10 Control panel, 50a, 50b Semiconductor element, 51a, 51b Diode, 52 Disconnection switch, 53 Current limiting circuit, 53a Nonlinear element, 53b Resistance element, 53c Switch, 54 Current meter, 55 Current measurement circuit, 56 Gate control circuit, 70 Capacitor, 71, 72 Semiconductor switch, 80 Control circuit, 81 Input unit, 82 Processor, 83 Memory, 84 Output unit, 85 Hardware circuit, 86 Processing circuit, 100 Power distribution system, T1 First delay time, T2 Second delay time.

Claims

1. A semiconductor circuit breaker installed in an electrical circuit connecting a power source and load equipment, Two semiconductor elements connected in series, with different directions of current interruption, Two diodes connected in parallel to each of the aforementioned semiconductor elements, A current limiting circuit connected in parallel to the semiconductor element, The system comprises a control device for controlling the aforementioned semiconductor element, The control device has a first delay time and a switching frequency at which the two semiconductor elements alternately switch on and off. From the time the semiconductor circuit breaker is closed until the first delay time has elapsed, the switching frequency is increased at a preset rate, and the semiconductor elements are switched on and off based on the switching frequency. A semiconductor circuit breaker characterized by the following features.

2. The current limiting circuit includes a nonlinear element. A semiconductor circuit breaker according to claim 1, characterized in that...

3. The current limiting circuit is The system comprises a resistive element and a switch arranged in series with the resistive element, The resistive element and the switch are connected in parallel with the nonlinear element. The control device performs control to turn on the switch after the first delay time has elapsed. A semiconductor circuit breaker according to claim 2, characterized in that...

4. The control device is set to have a second delay time that is longer than the time required from the time an off command is sent to the on-state switch until the off operation of the switch is completed. The control device performs control to turn off all of the semiconductor elements after the second delay time has elapsed following the transmission of an off command to the switch which is in the ON state. A semiconductor circuit breaker according to claim 3, characterized in that...

5. The semiconductor circuit breaker outputs a voltage to the load device at a frequency lower than the frequency of the power supply. A semiconductor circuit breaker according to any one of claims 1 to 4, characterized in that

6. The control device performs control that alternates between the operation of turning on one semiconductor element and turning off the other semiconductor element when the voltage supplied to the load device is positive, and the operation of turning off one semiconductor element and turning on the other semiconductor element when the voltage supplied to the load device is negative, at the switching frequency. A semiconductor circuit breaker according to any one of claims 1 to 4, characterized in that

7. The aforementioned semiconductor circuit breaker has a current compensation circuit having a capacitor and a semiconductor switch connected to the terminal on the load equipment side. The current compensation circuit, during the first delay time, when supplying voltage from the power supply to the load device, controls the semiconductor switch to charge the capacitor, and when not supplying voltage from the power supply to the load device, controls the semiconductor switch to discharge the capacitor and supply voltage to the load device. A semiconductor circuit breaker according to any one of claims 1 to 4, characterized in that

8. The control device has a set duty cycle and, until the first delay time has elapsed, turns the semiconductor element on and off based on the switching frequency, and within the period of the switching frequency, it controls the two semiconductor elements to be turned on alternately based on the duty cycle. A semiconductor circuit breaker according to any one of claims 1 to 4, characterized in that

9. The control device performs control to gradually increase the duty cycle at a preset rate of increase. A semiconductor circuit breaker according to claim 8, characterized in that...

10. Power supply and Load equipment connected to the aforementioned power supply via a control panel, A semiconductor circuit breaker according to any one of claims 1 to 4, comprising The aforementioned load device is an induction motor or a synchronous motor. A power distribution system characterized by the following features.