A flux controller that improves drive system performance by accounting for magnetic circuit saturation

This paper gives a theoretical and experimental comparison between three types of inner control loop strategy: a hysteresis current controller, a PID current controller, and a new design of flux linkage controller. The new controller uses a nonlinear feedback element to linearize the inner loop. The paper concludes that the new controller has significant advantages over the other two strategies when controlling magnetic circuits that are driven into saturation. However, it is the most complicated to implement, with extra circuitry required to estimate the flux linkage. The reluctance machine drive is used as one example of a system with a saturating magnetic circuit