A design method to reduce pulsating torque in PM assisted synchronous reluctance machines with asymmetry of rotor barriers

In this paper a design method for ferrite assisted synchronous reluctance machine is proposed in order to reduce torque ripple and cogging torque. An asymmetrical layout of the rotor flux barriers is proposed in order to reduce the harmonics components of the pulsating torque. The proposed analytical method is validated, employing finite elements simulations, for pure synchronous reluctance (SyR) and permanent magnet assisted synchronous reluctance machines (PMSyR) considering different slot-pole configurations. Simulated machines present a cogging torque and a torque ripple reduction respectively up to 92% and up to 70%. Moreover the electromotive force waveform is improved too. These results are achieved without reducing nominal torque and without increasing machines production costs.