Patent ID: 8228012

Claim:
A controller of a multi-phase electric motor comprising: a drive section, comprising an upper arm switching element and a lower arm switching element, for driving the multi-phase electric motor; a single current detection section for detecting a current value of the multi-phase electric motor; a pulse width modulation signal generation section for generating plural pulse width modulation of each phase within one control period based on the current value detected by the current detection section and a carrier signal; and a phase movement section for moving the pulse width modulation signal of a predetermined phase generated by the pulse width modulation signal generation section by gradually changing a movement amount of the phase in one control period, and outputting the resultant pulse width modulation signal to the drive section, wherein, if a movement amount of the phase of the predetermined phase in a control period immediately before is zero and a movement amount of the phase of the predetermined phase in a control period of this time is not zero, the phase movement section gradually increases a shift amount from zero in the control period of this time.