Design of a Rotary-Linear Motor With Unipolar SPM and Voice Coil Structure

In this article, a rotary-linear motor that achieves rotary and linear motions with a simple one-air-gap structure, low rotary ripple, and smooth linear force is proposed. The proposed motor combines a five-phase unipolar surface-mounted permanent-magnet (USPM) and a voice coil structure to simplify the motor structure, which motor can be named as rotary-linear surface-mounted permanent-magnet voice coil motor (RL-SVCM). And because of the characteristics of the rotary five-phase armature circuit and linear voice coil circuit, the proposed motor can provide low rotary ripple and smooth linear force. For designing the motor, the magnetic equivalent circuit (MEC) method is used to study the relationship between the linear force performance and motor structure parameters, and the effect of the flux bridges on the linear force and rotary torque. Due to uncertain variables in MEC, the FEM method is used to analyze the precise output result of rotary torque and linear force, and non-interaction between rotary and linear motions.