Dual-pole Line Start PM Motor With Variable Coil Number for Applications With Constant Load Torque

Dual-pole Line Start Permanent Magnet (LSPM) synchronous machine is an emerging technology that facilitates the two-speed operation in LSPM machines. However, the existing designs are typically suitable for applications with minimal load torque at the starting point such as fan-type type load. This paper aims to expand the application of dual-pole LSPM motors to loads with constant load torque by enhancing the motor starting capability. The starting torque enhancement is realized by altering the stator coil turn number at the starting point. This limits the braking torque at the starting point, which ultimately enhances the startup process. The number of coil turn is switched back to the original level at the steady state. The motor is modeled and simulated using Finite Element (FE) method.