A Comparative Study of Permanent Magnet Vernier Motors and Permanent Magnet Synchronous Motors for Robotic Joint Applications

The requirements for high torque density, high efficiency, and strong overload capacity in robot joints make the selection of motors critical. This paper presents a systematic comparison between permanent magnet vernier motors (PMVM) and permanent magnet synchronous motors (PMSM) tailored for robotic joint applications. First, a theoretical analysis of the working mechanism of PMVM is conducted. Based on the design specifications of joint motors, several PMVM models are then constructed, followed by a comparative evaluation of various PMVM topologies. The results show that PMVM design involves a trade-off between high torque density and high overload capability. Subsequently, a comprehensive comparison is conducted between the PMVM and a commercial joint PMSM under no-load, rated-load, and overload conditions. Finally, recommendations for motor selection under different load requirements are summarized, providing practical guidance for robotic joint applications.