APPLICATION OF SENSOR INTEGRATION TECHNIQUES TO SWITCHED RELUCTANCE MOTOR-DRIVES

This paper describes a novel drive system for a switched reluctance motor (SRM). The system needs no position sensor and has no discrete current sensors for regulating phase currents. In some systems, these sensors can constitute a substantial fraction of the system cost, compromise reliability, and add to size and weight. Instead of current sensors, the drive uses power MOSFET transistors with integrated pilot devices for current sensing. To compensate for the loss of current feedback when the switches are "off" a fixed off-time chopping strategy is used to control the phase currents. To eliminate the position sensor normally required for SR motor control, the controller estimates the rotor position using phase inductance measurements. The position estimation scheme is sufficiently precise to allow positioning of the phase firing pulses to within approximately two electrical degrees of the desired rotor angle, and full four-quadrant operation of the system is possible. A laboratory prototype system has been built and tested at speeds up to 3000 r/min. The system shows good performance in all four operating quadrants, including at zero speed. The entire control for the system is implemented in a single low-cost microprocessor.