Various design techniques to reduce cogging torque by controlling energy variation in permanent magnet motors

Using energy method, this paper analytically reveals that the cogging torqu e can be reduced by controlling N(L)th harmonic components of the square of airgap permeance function and flux density function, where NL denotes the least common multiple of number of poles and number of slots. As for design tools, it introduces various design techniques to reduce cogging torque wi th analytical formulation and FEM examples.