Patent ID: 8278854

Claim:
A control device which controls a controlled variable of an electric rotating machine by controlling a power inverting circuit to be set in one of a plurality of controlled states corresponding to respective controlled voltages of the power inverting circuit, comprising: a state determining section that determines one of the controlled states as a controlled state to be set in the power inverting circuit; and a control section that controls the power inverting circuit to change one controlled state, already set in the power inverting circuit, to the controlled state determined by the state determining section and to apply the controlled voltage, corresponding to the controlled state determined by the state determining section, to the electric rotating machine, the state determining section comprises: a current polarity judging unit that judges a polarity of a current which flows through the electric rotating machine in response to the controlled voltage corresponding to the controlled state already set in the power inverting circuit; a predicting unit that predicts the controlled variable of the electric rotating machine from information, indicating one controlled state to be set in the power inverting circuit, while performing the prediction based on the polarity of the current judged by the current polarity judging unit when the controlled state indicated by the information differs from the controlled state already set in the power inverting circuit, for each of the controlled states indicated by the information; and a state determining unit that determines the controlled state, to be set in the power inverting circuit, from the predicted controlled variables corresponding to the controlled states.