Analysis of Consequent Pole Spoke Type Vernier Permanent Magnet Machine With Alternating Flux Barrier Design

The mechanism of torque production in the Vernier machine is difficult to understand since the stator teeth originating flux modulation effects, upon which the torque is produced, are usually minor factors, which are ignored in normal synchronous machines. This paper begins with an analytical study of a spoke type Vernier permanent magnet machine (SVPM), which has a generic number of stator slots per pole per phase, upon which the key sizing equations are developed. An equivalent winding factor is defined to model stator teeth originating flux modulation phenomena and resulting multiharmonic field coupling effects. Performance predictions and design observations concerning SVPMs are then obtained. A new topology for an SVPM using ferrite magnets is proposed where a consequent pole design having an alternating leakage flux blocking ability is developed for the rotor. Overall, this improved SVPM design significantly boosts the back electromotive force compared to conventional SVPM, and the torque production even surpasses that of a benchmark rare earth interior permanent magnet machine (IPM) although with a slightly lower power factor.