Quantitative analysis for influence of structure parameters on the slot harmonic in fractional-slot permanent magnet motors

Finite-element method is adopted to calculate cogging torque of the fractional slot permanent magnet motor. The harmonic influence of each structural parameter on the fractional slot motor can be achieved by changing four structural parameters in turn. THD is imported to analyze the influence of every structural parameter on the higher harmonics in fractional slot permanent motors quantitatively. Quantitative calculations indicate that width of slot opening, pole arc coefficient and air-gap size can affect the higher harmonics of the fractional slot motor deeply. Therefore, optimizing width of slot opening, pole arc coefficient and air gap size can greatly weaken the higher harmonic content.