Patent ID: 6933701

Claim:
An apparatus for controlling a synchronous motor comprising: a current detector which detects current of a synchronous motor; a first coordinate converter which coordinate-converts the current detected by the current detector into a current on rotational biaxial coordinates (d-q axes) rotating at an angular frequency; a current controller which outputs a voltage command on the rotational biaxial coordinates such that a current on the rotational biaxial coordinates follows a current command on the rotational biaxial coordinates; a second coordinate converter which the voltage command on the rotational biaxial coordinates obtained from the current controller into three-phase voltage commands; an adaptive observer which calculates the angular frequency, an estimated current of the synchronous motor, an estimated rotor magnetic flux, and an estimated rotational speed based on the current on the rotational biaxial coordinates and the voltage command on the rotational biaxial coordinates; and an inverter which applies a voltage to the synchronous motor based on the voltage command, wherein the adaptive observer calculates the angular frequency such that a q-axis component of the estimated rotor magnetic flux is zero.