Abstract: According to one embodiment, a semiconductor device includes an n-layer and a p-layer arranged in a vertical trench structure in a drift layer. A depletion layer is formed to a depth of a trench of the vertical trench structure after a depletion layer spreads in a lateral direction between the n-layer and the p-layer when a voltage is applied between a drain and a source. A method for controlling the semiconductor device comprises detecting a voltage value between the drain and the source of the semiconductor device at turn-off and reducing a current value of a gate discharge current discharged from a gate in a first period. The first period starting before the detected voltage value greatly changes.

Abstract: A power conversion device includes: a power conversion circuit for converting DC power into AC power; and a controller to generate a control signal for the power conversion circuit based on a control command value and an output voltage of the power conversion circuit. The controller is configured to generate the control signal based on a corrected voltage command value calculated by subtraction correction to decrease a voltage command value when the output voltage of the power conversion circuit is equal to or higher than a predetermined threshold value, and to generate the control signal based on a voltage command value not subjected to the subtraction correction when the output voltage of the power conversion circuit is lower than the threshold value.

Abstract: A power system includes an AC power supply, an AC filter circuit, an AC circuit breaker, and a first switch. The AC filter circuit includes an inductor having one end connected in series to an output end of the AC power supply, and a capacitor having one end receiving a voltage at another end of the inductor. The AC circuit breaker exists between the other end of the inductor and an electric power grid. The first switch switches a state between the one end of the capacitor and a wire connecting the other end of the inductor to the AC circuit breaker, between a connected state and a disconnected state. The AC power supply may be a generator and include a generator control unit controlling the generator. The generator control unit may turn off the first switch when the AC power supply operates in a predetermined standby mode.

Abstract: A power conversion device includes: a power conversion circuit for converting DC power into AC power; and a controller to generate a control signal for the power conversion circuit based on a control command value and an output voltage of the power conversion circuit. The controller is configured to generate the control signal based on a corrected voltage command value calculated by subtraction correction to decrease a voltage command value when the output voltage of the power conversion circuit is equal to or higher than a predetermined threshold value, and to generate the control signal based on a voltage command value not subjected to the subtraction correction when the output voltage of the power conversion circuit is lower than the threshold value.

Abstract: According to an embodiment of the invention, a power conversion device that includes a power converter, a direct current capacitor, a voltage sensor, a rectifying element, an electromagnetic contactor, and a control circuit is provided. The power converter includes a pair of direct current terminals connected to a direct current power supply, includes multiple alternating current terminals connected to an electric power system of alternating current, converts direct current power input from the direct current power supply into alternating current power, and supplies the alternating current power to the electric power system. The direct current capacitor is connected between the pair of direct current terminals. The voltage sensor detects a voltage value of the direct current capacitor.

Abstract: A power system includes an AC power supply, an AC filter circuit, an AC circuit breaker, and a first switch. The AC filter circuit includes an inductor having one end connected in series to an output end of the AC power supply, and a capacitor having one end receiving a voltage at another end of the inductor. The AC circuit breaker exists between the other end of the inductor and an electric power grid. The first switch switches a state between the one end of the capacitor and a wire connecting the other end of the inductor to the AC circuit breaker, between a connected state and a disconnected state. The AC power supply may be a generator and include a generator control unit controlling the generator. The generator control unit may turn off the first switch when the AC power supply operates in a predetermined standby mode.

Abstract: According to an embodiment of the invention, a power conversion device that includes a power converter, a direct current capacitor, a voltage sensor, a rectifying element, an electromagnetic contactor, and a control circuit is provided. The power converter includes a pair of direct current terminals connected to a direct current power supply, includes multiple alternating current terminals connected to an electric power system of alternating current, converts direct current power input from the direct current power supply into alternating current power, and supplies the alternating current power to the electric power system. The direct current capacitor is connected between the pair of direct current terminals. The voltage sensor detects a voltage value of the direct current capacitor.

Abstract: An inverter controller is configured to control inverters connected in parallel. The inverter controller is configured to closes switch of a first inverter and turn on a first switching element provided at the first inverter to charge capacitors of the inverters at the time of starting the inverters, and to close the other switches after the capacitors are charged.

Abstract: A power converter includes inverters, AC sides of the inverters being connected in parallel, and a controller configured to control total output power of the inverters by controlling output power of at least one of the inverters in a control cycle shorter than a shortest communication cycle which allows communication with each of the inverters.

Abstract: An inverter controller is configured to control inverters connected in parallel. The inverter controller is configured to closes switch of a first inverter and turn on a first switching element provided at the first inverter to charge capacitors of the inverters at the time of starting the inverters, and to close the other switches after the capacitors are charged.

Abstract: A power converter includes inverters, AC sides of the inverters being connected in parallel, and a controller configured to control total output power of the inverters by controlling output power of at least one of the inverters in a control cycle shorter than a shortest communication cycle which allows communication with each of the inverters.

Abstract: A power converter includes inverters, AC sides of the inverters being connected in parallel, a power command value determiner configured to determine a first power command value and a second power command value, the first power command value being lower than a proportional division power value obtained by proportionally dividing a required power value required as total output power of the inverters based on respective rated outputs of the inverters, the second power command value being higher than the proportional division power value, and a controller configured to control output powers of the inverters at the first power command value and the second power command value determined by the power command value determiner.