| 摘要 |
A selection unit switches between a phase thetap and a phase thetan different from the phase thetap substantially by 180 degrees, and outputs one of them in synchronization with a carrier signal. A voltage-command generation unit generates and outputs three-phase voltage command values Vu*, Vv* and Vw* based on the phase outputted by the selection unit. A PWM-signal generation unit 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 according to a predetermined method, and generates six drive signals corresponding to switching elements of the inverter based on the three-phase voltage command values Vu*', Vv*' and Vw*' and the carrier signal. The PWM-signal generation unit 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.
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