An electric power conversion apparatus includes: an electric power conversion circuit that allows a DC terminal to be connected to a DC power source via a DC bus line, and performs at least one of converting DC power of the DC power source into AC power to output, or converting AC power into DC power to output; a DC switch turned on when the electric power conversion circuit performs electric power conversion; an AC switch provided on a side of the AC terminal, and turned on when the electric power conversion circuit performs the electric power conversion; a DC voltmeter that measures a potential at a predetermined portion, on a side of the DC terminal; a ground connection portion that connects the DC bus line and ground potential; and a control circuit connected to the electric power conversion circuit, the DC switch, the AC switch, and the DC voltmeter.

A protection function of an electronic device is realized with a lower cost. A load drive circuit 102 includes: transistors Qa and Qb for protection of an N-channel type connected between a power source terminal P1 and a power source end P7 for driving; an inverter circuit 14 that drives a load based on an input drive control signal Sd, the inverter circuit 14 being disposed between the power source end P7 for driving and a ground potential; and a booster unit 16 including a capacitor C1 having one terminal connected to an output end of the inverter circuit 14, the booster unit 16 generating, across another terminal of the capacitor C1, a voltage exceeding a power source voltage Vdc, and applying the voltage to control electrodes of the transistors Qa and Qb for protection.

A protection function of an electronic device is realized with a lower cost. A load drive circuit 102 includes: transistors Qa and Qb for protection of an N-channel type connected between a power source terminal P1 and a power source end P7 for driving; an inverter circuit 14 that drives a load based on an input drive control signal Sd, the inverter circuit 14 being disposed between the power source end P7 for driving and a ground potential; and a booster unit 16 including a capacitor C1 having one terminal connected to an output end of the inverter circuit 14, the booster unit 16 generating, across another terminal of the capacitor C1, a voltage exceeding a power source voltage Vdc, and applying the voltage to control electrodes of the transistors Qa and Qb for protection.

An apparatus and a method for controlling an inverter are disclosed. A method, according to one embodiment of the present disclosure, receives an operation command for an inverter, outputs a first PWM control signal, to an inverter unit, such that the inverter unit outputs at least one among a plurality of valid vectors for the diagnosis of a short circuit of the output of the inverter, and blocks the output of the inverter if a short circuit current of the inverter is detected.

The present invention relates to a circuit for protecting a switch of an electrical system, said protecting circuit comprising a variable electronic component having a physical characteristic the value of which varies by at least 10% as a function of temperature, the protecting circuit being configured to prohibit a current from passing through said switch when the intensity of said current exceeds a maximum allowed intensity threshold, said variable electronic component being connected in the protecting circuit such that the value of the maximum allowed intensity threshold is directly a function of said physical characteristic.

Methods and apparatus for detecting and characterizing arc faults in an aerospace electric propulsion system and then coordinating the operation of various elements of the protection system to execute a fault-clearing sequence. In a current-based method, the arc is detected and characterized based on differential readouts from current sensors. The difference between currents measured at two ends of a protection zone are compared to a difference threshold. In a power-based method, the arc is detected and characterized based on differential readouts from voltage and current sensors. The differential voltage and current readouts are used to compute the respective powers at two ends of a protection zone. The difference between the respective powers is integrated over a period of time and then the integrated difference is compared to a difference threshold. A differential protection trip mode is invoked when the difference threshold is exceeded.

An apparatus according to an embodiment includes a control circuit to control operations of an inverter and a switch. The control circuit judges whether or not a power system has a power failure, based on values of the system voltage and a frequency of the power system; and calculates a phase difference between a phase of the output voltage of the inverter and a phase of the system voltage and generate, by means of the phase difference, an output frequency pattern for changing a frequency of the output voltage of the inverter. The control circuit, when it is judged that the power system has recovered from the power failure, controls the inverter to change the frequency of the output voltage of the inverter in line with the output frequency pattern, and closes the switch after the phase difference becomes smaller than or equal to a threshold.

A protection system including: a DC power supply; a power converter that converts DC power of the DC power supply into AC power, a circuit breaker that is series-connected to an electrical path located between the DC power supply and the power converter and can open the electrical path; a DC capacitor connected to a circuit located in the power converter; a timer that counts a lapse of a predetermined length of time from turn-on of the circuit breaker; a current detector that detects current flowing in the power converter; and a protection determiner that issues an open operation command to the circuit breaker when the current detector does not detect a decrease in the current after the timer has counted a lapse of the predetermined length of time from turn-on of the circuit breaker.

A protection system including: a DC power supply; a power converter that converts DC power of the DC power supply into AC power, a circuit breaker that is series-connected to an electrical path located between the DC power supply and the power converter and can open the electrical path; a DC capacitor connected to a circuit located in the power converter; a timer that counts a lapse of a predetermined length of time from turn-on of the circuit breaker; a current detector that detects current flowing in the power converter; and a protection determiner that issues an open operation command to the circuit breaker when the current detector does not detect a decrease in the current after the timer has counted a lapse of the predetermined length of time from turn-on of the circuit breaker.

A method for controlling a three-level brake chopper and a three-level brake chopper including, a first controllable semiconductor switch connected between a positive direct current pole and a first connection point, a second controllable semiconductor switch connected between the first connection point and a neutral direct current pole, a third controllable semiconductor switch connected between the neutral direct current pole and a second connection point, a fourth controllable semiconductor switch connected between the second connection point and a negative direct current pole, resistance means connected between the first connection point and the second connection point, and control means configured to control the second controllable semiconductor switch and the third controllable semiconductor switch into a conducting state in response to detecting a fault in the resistance means.