Rotary-linear motor with unipolar SPM and voice coil for simple structure and low ripple output performance

Abstract

In this thesis, 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) motor structure and a voice coil motor structure to simplify the motor, which 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 and rotary torque output performance and RL-SVCM 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. And also for increasing the output density of the RL-SVCM, the different end-structures of flux bridges on RL-SVCMare studied, including the full-ring, half-ring, and PMs flux bridges. Because the half-ring end structure interacts with the five-phase rotary coil on the stator to generate reluctance torque, which improves the rotary torque output of the motor without increasing PM. While the torque ripple is also increased and have a little coupling effect. When PMs flux bridges are compared with the full-ring type, the rotary torque increases significantly without increasing torque ripple and no coupling effect. At last, a structure with PM as the end magnetic bridge was manufactured. The experimental results of the prototype are in great agreement with the simulation results of FEM.