Panasonic Intellectual Property Management Co., Ltd.

Masashi Okamatsu

Takashi Ueda

Hideki Tanaka

Katsuya Hagiwara

Masahiro Tochigi

A power inverter device includes an inverter that converts a direct-current (DC) power to an alternating-current (AC) power having an output AC voltage, and a capacitor circuit electrically connected to the inverter. The capacitor circuit is operable to start supplying a capacitor voltage to the inverter at a time point when a predetermined waiting time lapses from a zero cross point of the output AC voltage at a starting up of the inverter circuit, wherein the capacitor voltage has a phase shifted by &#x3c0;/4 radian from the output AC voltage. The inverter is operable to generate the output AC power based on the capacitor voltage and the DC power. The predetermined waiting time is a duration is equal to 2&#x3c0;n+3&#x3c0;/4 radian or 2&#x3c0;n+7&#x3c0;/4 radian of a phase of the output AC voltage (n is an integer not smaller than zero). This power inverter device can reduce a ripple power of the input power early after the starting-up.

Power converter including a DC-AC inverter and a capacitor circuit

A DC-DC converter includes first and second switching devices electrically connected in series between an input terminal and a ground terminal, third and fourth switching devices electrically connected in series between an output terminal and the ground terminal, an inductor, a drive circuit that drives the first switching device to turn on and off, a bootstrap capacitor circuit connected electrically to the drive circuit, and a control circuit. The control circuit is operable to turn on and off the switching devices serially connected with each other after a simultaneous-off duration for which both of the switching devices are continuously turned off. The control circuit is operable to charge the bootstrap capacitor by continuously turning on keeping the second switching device for a charging duration while continuously turning off the first switching device for a sustaining duration determined by the simultaneous-off duration and the charging duration. This DC-DC converter can reduce a current ripple even when the bootstrap capacitor is charged.

DC-DC converter

A DC-DC converter includes a switching device, a drive circuit for turning on and off the switching device, a bootstrap capacitor electrically connected to the drive circuit, and a control circuit electrically connected to the drive circuit. The control circuit is operable to charge the bootstrap capacitor for a charging duration periodically at a charging period longer than an on-off period at which the switching device is turned on and off periodically. This DC-DC converter performs efficient boost and step-down operations.

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Osaka, Japan

Masashi Okamatsu