Unified Complex Vector Current Controller for AC Machine Drives

In electric drives, steady-state and the transient system characteristics are both essential for high-performance industrial applications. In a control chain with current, speed and position loops, the bandwidth of the first inner loop imposes practically the performances of the others. On the inner current-loop dynamics depends the speed and position loops dynamics, and finally of the whole system. So, for a fast and accurate drive control, a special attention should be paid to the current controller design. This paper presents a unified complex vector current controller that can be used, with minor changes, for all type of AC machine drives. Being based on theory of the complex vector current controller mainly developed for magnetically isotropic machines, it inherits its well-known advantages. On the other hand, in order to be implemented, it is based on the active-flux concept, which allows the transformation of a magnetically anisotropic machine into a fictitious magnetically isotropic one. Some experimental results confirm the feasibility of the proposed unified complex vector current controller.