Control of a switched-reluctance aircraft engine starter-generator over a very wide speed range

An electric direct-drive gearless starter-generator has been designed and built for an aircraft-engine application. The system is based on a switched reluctance motor, which was chosen for its simplicity, ruggedness, high-speed capability, and efficiency. A description is given of motor control system algorithms and hardware, which are used to control the motor over its operating speed range from standstill to 48000 RPM in both monitoring and generating modes. Novel features of the starter-generator control system are a closed-loop regulator which controls the amount of firing angle advance to maintain optimum torque production at high speed, and a hardware-based digital commutation controller which generates phase firing pulses for the inverter on the basis of machine rotor angle, pulse width, and pulse advance