Dynamic performance enhancement of small single-phase line-start PM motors

To improve the dynamic performances of a 2-poles small single phase brushless permanent magnet motor (SP-BLPMM), suitably shaped auxiliary PM (APM) are proposed in the paper. The electromechanical model of SP-BLPMM – integrated in a small pump application without APM – is then preliminary assessed by the experimental data elaboration. Afterwards, the benefits due to the APM are analyzed by both preliminary magneto-static finite element analysis (FEAs) and transient solutions. By optimizing the APM geometry and magnetization pattern the starting torque is appreciably increased and speed oscillations at load are reduced.