Design and Control of Wireless Hybrid Stepper Motor System

This paper proposes and implements a wireless hybrid stepper motor (HSM) system, which offers high controllability of speed, direction, and position without physical contact and electrical connection between the power source and the motor. By transmitting electrical pulses to each motor winding in different frequencies, duty ratios, and sequences, the speed can be regulated to expected values, and the rotation angle of each step and direction can be controlled without any sensors or controllers at the secondary side. Two orthogonal bipolar coils and double-frequency resonant networks are adopted to provide four decoupled current channels to control the four self-drive switches independently at the secondary side. Thus, various operating modes can be realized for different working requirements. To equalize the power output at all phases, pulse frequency modulation (PFM) is adopted to maintain robust zero-voltage switching (ZVS). The motor can carry a 1.5-Nm load at the speed of 430 rpm and provides speed and position control capability. Theoretical analysis, computer simulations, and hardware experimentations are given to verify the feasibility of the proposed wireless HSM system.