Patent ID: 8077491

Claim:
An inverter controller comprising: an inverter main circuit that supplies a power to a three-phase load; and a pulse-width-modulation operation unit that outputs a switching command to the inverter main circuit, wherein the pulse-width-modulation operation unit includes a modulation-mode selecting unit that selects an optimal two-phase modulation mode signal for modulation and a carrier-wave-synchronous-mode select command based on information on a voltage command value for applying a voltage to the three-phase load, a modulation-wave generating unit that generates a modulation wave as a voltage command value to the inverter main circuit in response to the two-phase modulation mode signal, a carrier-wave generating unit that generates a carrier wave that becomes a reference for the switching command in response to the carrier-wave-synchronous-mode select command, and a comparing unit that compares the modulation wave and the carrier wave and determines a switching pattern based on a result of comparison, and in a two-phase modulation mode in which switching of any one of three phases configuring the inverter main circuit is turned off, the pulse-width-modulation operation unit controls the carrier-wave generating unit such that a carrier wave frequency that is a frequency of the carrier wave is set to an integral multiple of a modulation wave frequency that is a frequency of the modulation wave.