Synchronous frame current control of multi-phase synchronous motor. Part I. Modeling and current control based on multiple d-q spaces concept under balanced condition

In this paper, the synchronous frame current control of a multi-phase synchronous motor based on multiple d-q spaces concept is proposed. The proposed method can not only possess the superiority of a linear controller over the conventional hysteresis-type current controller but it also enables the current to be regulated without a steady state error. The key idea is that all the harmonics of the current and voltage, which can contribute to the torque positively, can be equivalently represented as dc components. Through out this paper, a five-phase synchronous motor is used as a practical example and the basic concepts can be easily extended into an n-phase ac motor. Experimental results prove the validity of the proposed method.