Patent ID: 9276508
Filing Date: 2016-03-01
CPC Classification: H02P,Y02P

Claim Text:
1. An inverter device for driving an electric motor, comprising: a PWM-waveform generation section which generates a waveform for performing PWM control on the electric motor; a rotational-speed detection section which detects a rotational speed of the electric motor; a carrier-frequency calculation section which calculates a carrier frequency on the basis of the rotational speed detected by the rotational-speed detection section; and a carrier-frequency switching section which switches the carrier frequency of the waveform generated by the PWM-waveform generation section, on the basis of the calculated carrier frequency, wherein the carrier-frequency calculation section calculates, as the carrier frequency, a frequency which is increased with an increase in the electric-motor rotational speed detected by the rotational-speed detection section, and wherein the carrier-frequency calculation section calculates a fundamental carrier frequency on the basis of the electric-motor rotational speed and calculates a carrier frequency to be actually used by multiplying the fundamental carrier frequency by a gain depending on at least one of an output torque from the electric motor and a load inertia.