Patent ID: 8471507

Claim:
An electrical power conversion system, comprising: a motor; an inverter circuit that outputs a U-phase current, a V-phase current, and a W-phase current to the motor; a current sensor that detects the U-phase current, the V-phase current, and the W-phase current; and a control circuit that controls the inverter circuit based on a torque command value and values detected by the current sensor, so that the U phase current, the V-phase current, and the W-phase current outputted from the inverter circuit are formed as sine waves; wherein: the control circuit comprises: a current component extraction unit that, based on the values detected by the current sensor, for each phase, extracts high frequency current components superimposed upon the U-phase current, the V-phase current, and the W-phase current; and an AC current abnormality detection unit that detects an abnormality of an AC current flowing to the motor, based on the phases of the high frequency current components for any two phases among the U-phase current, the V-phase current, and the W-phase current; the high frequency current components are components having a frequency that is higher than a fundamental frequency of the U-phase current, the V-phase current, and the W-phase current; the current component extraction unit extracts the high frequency current components by determining differences between the values detected by the current sensor and three phase command currents that are calculated based on the torque command value; and the AC current abnormality detection unit determines that there is an abnormality if a phase difference between the high frequency current components for any two phases among the U-phase current, the V-phase current, and the W-phase current is approximately 180°.