Modeling and four quadrant control of a sensorless switched reluctance motor driven actuator system

This dissertation presents the modeling, control, simulation and implementation of a four-quadrant servo-type switched reluctance motor (SRM) drive system. The development of the system is focused on a simplified SRM model developed for the controller, application based appropriate control, elimination of rotor position sensor, outer loop control and engineering solutions needed to overcome the practical problems.; A simpler, but quite accurate, model is essential for the SRM controller for real time application. A geometry based simplified analytical model that decouples the current and position effect on flux and torque in the SRM drive is developed in this dissertation. This model gives a direct relation between phase current and torque accounting for the high degree of non-linearity of the machine. A simple flux model and its inverse relationship have been developed to meet diverse requirements of controller design. The dissertation emphasizes and demonstrates the importance of these relationships for real time controller implementation of high performance SRM drives.; A four-quadrant controller for SRM drives with optimal turn-on and turn-off angles for each operating quadrant is developed in this dissertation. The firing angles are chosen to maximize the average torque produced by the motor, which requires the optimization of the area of the energy conversion loop. The four-quadrant SRM controller developed with the chosen optimization criterion gives fast motoring response as well as fast braking response. One of the main underlying contributions of this dissertation is the development and solution of an optimal control problem to provide the best control strategies. The dissertation also provides the specific guidelines to switch the firing angle position when the motor operation changes from one quadrant to another. The developed four-quadrant controller has been applied to control the linear displacement of a highly dynamic actuator load.; A four-quadrant sensorless controller for SRM drives is also presented in this dissertation. A hybrid sensorless technique is also developed for highly dynamic actuator loads. The drive system delivers excellent dynamic performance over a wide speed range including zero speed. The problems associated with practical implementation especially at low and zero speeds have been addressed and overcome with engineering solutions. A chapter is devoted to the design for the outer loop controller of a drive system based on PID and feed forward control technique.; Experimental results for a 1.0 kW switched reluctance motor obtained on a dSPACE-based platform are presented along with useful guidelines for prototype implementation.