Rotor Position Feedback Over an RF Link for Motor Speed Control

In this paper, we demonstrate the feasibility of controlling the speed of an induction motor using a wireless position feedback over an RF link, and compare its performance under dynamic- and steady-state conditions with those obtained by using a wire-based position feedback control. The wireless scheme precludes the need for the cable that feeds the position from the sensor to the controller, thereby minimizing feedback noise pickup and cost for some applications. It also raises the possibility of using a low-resolution, low-cost sensor, which, along with the use of simple estimation algorithms, may potentially provide an alternative to or backup support for conventional position sensorless control for a wide range of motors and speeds. Further, using a composite Lyapunov-function-based approach, we determine the effect of time delay (due to wireless communication) on the stability of the overall system.