Patent ID: 8664906

Claim:
A motor control device having a function of detecting a rotor position of a synchronous motor without a sensor, wherein the motor control device comprises: current detecting means for detecting a current flowing through a coil of the synchronous motor; applied voltage detecting means for detecting an applied voltage applied to the coil of the synchronous motor; current peak value and electrical angle detecting means for detecting a current peak value and a current electrical angle on the basis of the current detected in the current detecting means; induced voltage peak value and electrical angle detecting means for detecting an induced voltage peak value and an induced voltage electrical angle on the basis of the current detected in the current detecting means and the applied voltage detected in the applied voltage detecting means; and rotor position detecting means for detecting the rotor position by directly finding the rotor position from a rotor position expression containing, as a variable, the current electrical angle or the induced voltage electrical angle from among the current peak value and the current electrical angle detected in the current peak value and electrical angle detecting means and the induced voltage peak value and the induced voltage electrical angle detected in the induced voltage peak value and electrical angle detecting means, and containing, as a variable, a current phase or an induced voltage phase capable of being selected using at least two of (a) the current peak value, (b) the induced voltage peak value and (c) the induced voltage electrical angle less the current electrical angle as parameters from a predefined data table.