Patent ID: 7548443

Claim:
An apparatus for generating a three-phase pulse-width-modulation signal for a three-phase voltage inverter employing a semiconductor switching element, the apparatus comprising: a generating unit that generates the three-phase pulse-width-modulation signal based on a combination of three basic voltage vectors and a zero vector wherein the generating unit includes a creating unit that creates two basic voltage vectors having a phase difference of 60 degrees and at least a zero vector by allocating occurrence time ratios for two basic voltage vectors having a phase difference of 60 degrees with a voltage command vector therebetween and a corresponding zero vector based on the voltage command vector; and a distributing unit that distributes an occurrence time ratio of the voltage command vector to three basic voltage vectors having a phase difference of 120 degrees including one of the two basic voltage vectors having a phase difference of 60 degrees, using three vectors with equal lengths having a phase difference of 120 degrees and constituting a zero vector corresponding to the voltage command vector, to create three basic voltage vectors having a phase difference of 60 degrees and a zero vector based on the occurrence time ratio distributed.