摘要 |
Switching elements in an inverter main circuit are responsive to switching control signals. Phase voltages are applied to a polyphase load via the switching elements. Basic voltage command values are generated for phases of the polyphase load respectively. The basic voltage command values are converted into final voltage command values respectively. During a time interval for which at least two of the basic voltage command values are approximately equal to each other, the final voltage command values corresponding to the two of the basic voltage command values are equal to one of a maximum and a minimum. A carrier wave is subjected to pulse-width modulation responsive to the final voltage command values to produce the switching control signals. The produced switching control signals are outputted to the switching elements in the inverter main circuit. |