Patent ID: 6850030

Claim:
A method for controlling an electric current of a synchronous motor in which a power conversion circuit is provided with an appropriate actual voltage command such that an electric current flowing through the synchronous motor fed with power from the power conversion circuit coincides with a current command, the method comprising the steps of: converting electric currents Iu, Iv, and Iw, flowing through the synchronous motor, into a d-axis actual current Idfb and a q-axis actual current Iqfb on rotational coordinate axes which rotate synchronously with a rotor magnetic flux vector on the basis of an actual position θ of the rotor of the synchronous motor; estimating a d-axis simulated current Idob and a q-axis simulated current Iqob on the basis of the d-axis actual current Idfb, the q-axis actual current Iqfb, a d-axis actual voltage command Vdref, and a q-axis voltage command Vqref; generating the d-axis actual voltage command Vdref and the q-axis actual voltage command Vqref on the basis of a d-axis current command Idref, a q-axis current command Iqref, the d-axis simulated current Idob, and the q-axis simulated current Iqob; and converting the d-axis actual voltage command Vdref and the q-axis actual voltage command Vqref into actual voltage commands Vuref, Vvref, and Vwref on the basis of the actual position θ of a rotor of the synchronous motor.