Power conversion device and refrigeration/air-conditioning system

摘要

A power conversion device according to the present invention includes a power supply, a booster unit (a reactor, a switch) that boosts a voltage supplied from the power supply by switching control, a smoothing circuit that smoothes an output voltage from the booster unit, a rectifier that is arranged between the booster unit and the smoothing circuit to prevent a current reverse flow toward the booster unit, and a commutation unit that is connected to the rectifier in parallel to commutate a current flowing through the rectifier toward itself.

主权项

1. A power conversion device comprising:
a power supply unit; a booster unit that boosts a voltage supplied from the power supply unit by switching control; a smoothing unit that smoothes an output voltage from the booster unit; a backflow prevention element that is arranged between the booster unit and the smoothing unit to prevent a current reverse flow toward the booster unit; a commutation unit that is connected to the backflow prevention element in parallel to commutate a current flowing through the backflow prevention element in a predetermined period before a short-circuit current begins to flow in response to the switching control of the booster unit; and a determination unit that determines a duty ratio of the switching control and an implementation period of a commutation operation by the commutation unit, based on a plurality of thresholds and a comparison target signal that is a triangle-wave signal or a sawtooth signal, wherein the thresholds include a first threshold, a second threshold that is equal to or larger than the first threshold, and a third threshold that is equal to or smaller than the first threshold, and the determination unit determines the duty ratio based on a comparison result between the first threshold and the comparison target signal, and determines the implementation period based on a comparison result between the third threshold and the comparison target signal.