Panasonic Intellectual Property Management Co., Ltd.

Shogo Hirota

Kenji Hanamura

Takashi Shirakawa

Hiroyuki Fujii

Wataru Horio

For power transfer from a first DC part to a second DC part in a dual active bridge (DAB) converter by stepping down a voltage, a first bridge circuit includes a period in which the first DC part and a primary winding of an insulated transformer conduct and a period in which ends of a primary winding of the insulated transformer are short-circuited in the first bridge circuit. A second bridge circuit includes a rectification period. A control circuit variably controls a phase difference between a first leg a the second leg, variably controls a simultaneous off period of a fifth switching element and a sixth switching element, and variably controls a simultaneous off period of a seventh switching element and an eighth switching element.

Power conversion device

For power transfer from a first DC part to a second DC part in a dual active bridge (DAB) converter by stepping up a voltage, the second bridge circuit includes a period in which a secondary winding of an insulated transformer and the second DC part conduct and a period in which ends of the secondary winding of the insulated transformer are short-circuited in the second bridge circuit. A control circuit fixes a phase difference between a first leg a the second leg, variably controls a simultaneous off period of a fifth switching element and a sixth switching element, and variably controls a simultaneous off period of a seventh switching element and an eighth switching element.

An inverter circuit includes a plurality of flying capacitors and converts a DC voltage supplied from a DC power supply into an AC voltage. A filter circuit approximates a waveform of an output voltage of the inverter circuit to a sinusoidal wave. An excess current protection circuit supplies a block signal for turning off a plurality of switching elements to the driving circuit when an excess current is detected. When at least one of an abnormal voltage in any of the plurality of flying capacitors and an abrupt change in an output voltage of the power converter occurs, voltages other than a positive voltage of the DC power supply, a negative voltage of the DC power supply, and a zero voltage are restricted from being output from the inverter circuit.

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Osaka, Japan

Shogo Hirota