Proposal of current integral zero power control with force feedforward for helical motor

This paper investigates three zero power control methods for a helical motor, which are current integral type, external force feedback type, and current integral with feedforward type. A helical motor is a linear motor having helical mover and stator that can realize a high thrust force density and high back-drivability. The magnetic levitation control, position control and force control were archived. Additionally, power-saving magnetic levitation by a zero power control was successfully realized. However, a gap response with current-integral type and external-force-feedback type has an undershoot on a force control. This paper proposes a current-integral zero-power control with force feedforward to suppress the undershoot, and compare it with current-integral and external-force-feedback. As a result, on the force control, we confirm the proposed method suppresses the undershoot and improve the transition time compared with the conventional methods.