| 摘要 |
An object of the present invention is to heat a refrigerant stayed in a compressor efficiently. A selection unit 23 switches between a phase ¸p and a phase ¸n different from the phase ¸p substantially by 180 degrees, and outputs one of them in synchronization with a carrier signal. A voltage-command generation unit 25 generates and outputs three-phase voltage command values Vu*, Vv* and Vw* based on the phase outputted by the selection unit 23. A PWM generation unit 26 generates three-phase voltage command values Vu*', Vv*' and Vw*' by correcting the three-phase voltage command values Vu*, Vv* and Vw* outputted by the voltage-command generation unit 25 according to a predetermined method, and generates six drive signals corresponding to switching elements of the inverter 9 based on the three-phase voltage command values Vu*', Vv*' and Vw*' and the carrier signal. The PWM generation unit 26 outputs the generated drive signals to the corresponding switching elements of the three-phase inverter, to cause the inverter to generate a high-frequency AC voltage. |
