Patent ID: 8030874

Claim:
A power converting apparatus comprising: an input-circuit unit that receives an input voltage that is either a direct-current voltage or an alternating-current voltage, and converts the input voltage to a direct-current voltage; an inverter unit that converts the direct-current voltage from the input-circuit unit to an alternating-current voltage with a predetermined frequency for driving an alternating-current motor; and a PWM-waveform generating unit that generates a PWM waveform for controlling switching of a switching element in the inverter unit and outputs the PWM waveform, wherein when the alternating-current motor is to be driven in a three-pulse mode, three pulses included within a ½ cycle of an inverter frequency in the PWM waveform that is output by the PWM-waveform generating unit are set to satisfy Tq≧T/ 8, Tp≦Tq/ 2, and Tr≦Tq/ 2 where, the three pulses include a first pulse, a second pulse, and a third pulse from an order of generation, Tp is a pulse width of the first pulse, Tq is a half of a pulse width (full width at half maximum of a pulse) of the second pulse, Tr is a pulse width of the third pulse, and T is a cycle of the inverter frequency.