Synchronous motor control system and method of controlling synchronous motor

摘要

The synchronous motor control system of the present invention improves the mechanical output per unit weight of a synchronous motor using three phase alternating currents of sine-wave curve as a power source, simultaneously with an increase in the minimum torque thereof. The synchronous motor control system transforms phase currents Iu and Iv to electric currents Id and Iq in a d-q coordinate system, based on the electrical angle &thetas;. Input electric current command values (target electric currents) Id* and Iq* are multiplied by a coefficient of correction, which is mapped to the electrical angle &thetas;, to yield corrected target electric currents Ids* and Iqs*. Three phase voltages Vu, Vv, and Vw are eventually output as feedback controlled variables, based on the respective differences between the corrected target electric currents Ids* and Iqs* and actual data of d-axis and q-axis electric currents Id and Iq. This process enables the target phase current for producing the primary magnetic flux of a revolving magnetic field to be continuously kept at its peak value and to have a substantially trapezoidal waveform. The structure of the present invention significantly improves the mean torque while remarkably increasing the minimum torque in the torque ripples, which have a cycle of electrical angle of 60 degrees and are observed in a synchronous motor.