AN IMPROVED HIGH-RESOLUTION HYBRID STEPPER MOTOR FOR SOLAR-ARRAY DRIVE OF INDIAN REMOTE-SENSING SATELLITE

This paper presents the computer-aided design and development of an im proved 720-steps hybrid stepper motor used as the drive motor for the solar array of the Indian remote-sensing (IRS) satellite in the polar sun-synchronous orbit. The motor is of pancake type with coil redundan cy, and the step angle is 0.5 degrees. It is designed to deliver a con stant holding torque of 1 N.m against a varying de supply voltage of 2 8-42 V and in an operating temperature range from -10 degrees C to +60 degrees C. The authors introduce a phenomenon named as ''torque satur ation,'' achievable in a hybrid stepper motor by properly choosing the operating point of the rotor permanent magnet and the stator winding configuration. Apart from the computer-aided design procedure, relevan t details regarding fabrication and testing are also provided. The tes t results of the developed motor match fairly with the computed values and confirm the high performance of the developed hybrid stepper moto r.