Power conversion apparatus and refrigeration air-conditioning apparatus

A refrigeration air-conditioning apparatus comprising, for driving at least one of a compressor and an air-sending device,

• a power converter for converting electric power between a power source and a load, the power converter including:
• a voltage changing device including a rectifier configured to prevent a backflow of a current from the load to the power source, the voltage changing device being configured to change a voltage of electric power supplied from the power source to a predetermined voltage;
• a commutation device configured to perform a commutation operation of directing a current flowing through the voltage changing device to another path;
• and
• a controller configured to perform control related to the voltage change of the voltage changing device and control related to the commutation operation of the commutation device,
• wherein the commutation device is configured to direct, when the commutation device performs the commutation operation, a current generating a voltage causing reverse recovery of the rectifier to the commutation device,
• wherein the commutation device includes a transformer configured to apply a voltage, induced by a current flowing through a primary-side winding of the transformer, to a secondary-side winding of the transformer on the other path, and
• wherein a turns ratio between the primary-side winding and the secondary-side winding of the transformer is adjusted so that the current generating the voltage causing the reverse recovery of the rectifier flows through the commutation device while making a return current flowing on a side of the primary winding smaller than a current capacity of each element connecting to the primary winding.