In switching between asynchronous PWM control and synchronous PWM control, control can be simplified. An apparatus has a first pulse pattern generation processing module which generates a synchronous PWM signal in a first pulse pattern formed of multiple pulses defined in accordance with two or more parameters based on a voltage command value, and a second pulse pattern generation processing module which generates a synchronous PWM signal in a second pulse pattern formed of a single pulse. The first pulse pattern generation processing module modifies the individual parameters in switching pulse patterns between the first pulse pattern and the second pulse pattern. The individual parameters are modified to move the pulse patterns, and thus control can be simplified.