Force and Velocity Ripple Reduction of the New Linear Motor

This study presents a new linear motor with an E-core stator and a homopolar permanent magnet (PM) mover. The velocity and force ripples of the motor are effectively reduced by an optimized structure and effective force compensation. Firstly, the mechanical structure, magnetic paths and operation principles are introduced. Force analysis is carried out via magnetic circuit method and finite element method (FEM). The magnetic structure of the motor is optimized to reduce the cogging force. Secondly, a force compensation approach is developed to control the velocity and reduce the force ripples of the motor. Parameter identification is employed for the force control to observe the force of the motor so as to compensate the force ripples. Finally, the velocity ripples and force ripples are calculated and measured by simulation and experimentation. Both the simulation and experimental results show high feasibility of the force compensation method. By optimizing the magnetic structure of the motor and developing the force compensation block of the control part, the estimated force output suggests that the force ripples of the motor can be limited within 5%.