Patent ID: 8344680

Claim:
A control apparatus of an alternating-current motor, comprising: an inverter which is connected to a direct-current source and outputs three-phase alternating currents of arbitrary frequency and arbitrary voltage to the alternating-current motor; a current detector which detects a current of the alternating-current motor; a voltage command/PWM signal generation unit which calculates an output voltage command of the inverter based on a signal from the current detector, and generates a pulse width modulation signal to control a switching element, which is arranged in the inverter, based on the output voltage command; and a motor current imbalance compensation unit which generates motor current imbalance compensation amounts of the corresponding phases based on the currents of at least any two of the phases among the currents detected by the current detector and sets a motor current imbalance compensation amount of the remaining one phase to be zero, wherein the voltage command/PWM signal generation unit directly or indirectly adjusts the pulse width modulation signal of the two phases based on the current imbalance compensation amounts.