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 improved 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 redundancy, and the step angle is 0.5°. It is designed to deliver a constant holding torque of 1 Nm against a varying DC supply voltage of 28-42 V and in an operating temperature range from -10°C to +60°C. The authors introduce a phenomenon named as “torque saturation”, 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, relevant details regarding fabrication and testing are also provided. The test results of the developed motor match fairly well with the computed values and confirm the high performance of the developed hybrid stepper motor