AC TO DC Rectifier Control Logic Customer I/O DC to AC Inverter ...
How Does an AC VFD Work? An ac . the speed of a three phase induction motor . . pulses and making them appear to the motor as a 3 phase sine wave.
http://www.yaskawa.com/site/dmdrive.nsf/link2/MNEN-5JFQPK/$file/AR.AFD.03.pdf