Patent ID: 8395338

Claim:
A control system for a multiphase rotating machine comprising: a power conversion circuit including a plurality of switching elements, which is formed of high potential side switching elements connecting respective phases of the multiphase rotating machine to a high potential side input terminal of the power conversion circuit, and low potential side switching elements connecting the respective phases to a low potential input terminal of the power conversion circuit, the power conversion circuit rendering a first phase of the multiphase rotating machine conductive to the high potential side input terminal of the power conversion circuit, and rendering a second phase conductive to the low potential side input terminal of the power conversion circuit to apply a voltage of a rectangular waveform to the multiphase rotating machine; and a control unit for operating the switching elements so as to alternately change over between a first state in which the first phase is rendered conductive to the high potential side input terminal through a high potential side switching element of the first phase and the second phase is rendered conductive to the low potential side input terminal through a low potential side switching element of the second phase, respectively, and a second state in which the first phase is rendered conductive to the low potential side input terminal through a low potential side switching element of the first phase and the second phase is rendered conductive to the high potential side input terminal through a high potential side switching element of the second phase, respectively, so as to modulate the voltage of the rectangular waveform in pulse width, wherein the control unit is configured to control all switching elements of the plurality of switching elements forming the first state and the second state by pulse width modulation as the first state and the second state are alternately changed over.