Abstract: A semiconductor driving device includes: a control unit which generates an ON/OFF command for a semiconductor switching element; a gate power supply unit which generates voltage to be applied between a gate terminal and a source terminal of the semiconductor switching element; a gate driving unit which applies the voltage generated by the gate power supply unit, between the gate terminal and the source terminal; and a gate leakage current detection unit which detects gate leakage current of the semiconductor switching element on the basis of voltage occurring at a gate resistor connected to the gate terminal, using a negative-side potential of the gate power supply unit as a reference.

Abstract: A power converter includes: a converter including four switching elements in full bridge configuration, the converter converting alternating-current power supplied from an alternating-current power supply into direct-current power; a reactor provided between the alternating-current power supply and the converter; a smoothing capacitor connected between direct-current terminals of the converter; an alternating-current voltage detector detecting an alternating-current voltage output from the alternating-current power supply; an alternating current detector detecting a current flowing through the reactor; and a control circuitry controlling a switching operation of the switching elements. The control circuitry controls the switching elements such that a potential fluctuation due to the switching operation is reduced between a P terminal of the converter and an L terminal of the alternating-current power supply, or between a G terminal of the converter and an N terminal of the alternating-current power supply.

Abstract: A power converter includes: a converter that includes switching elements to convert alternating current (AC) power output from an AC power source into direct current (DC) power; a reactor disposed between the AC power source and the converter; a smoothing capacitor connected to both ends of a DC terminal of the converter; and detectors that detect a physical quantity representing an operational state of the converter. A bus voltage command value is issued that has zones respectively having different change rates during boost operation of the converter, where the change rates each represent how a bus voltage included in the physical quantity changes with a change in a magnitude of the load obtained from the physical quantity.