Steady-state characteristics of a shaded-pole motor by finite element analysis

The authors model only one pole pitch of a shaded-pole motor, exploiting the inherent periodicity of the boundary conditions. Excitation for the model is derived directly from the applied stator voltage which is not restricted to any particular time variation. Rotor motion is simulated by moving one pole pitch of the rotor in discrete spatial steps and tying this movement to the time step used in the discretisation of the excitation voltage waveform. At each time step and rotor position the field solution is coupled to the external electrical circuit and the current is determined taking magnetic nonlinearity of the permeable regions into account. Continuous motion of the rotor is simulated by returning the rotor to its starting position after movement through one pole pitch. The technique does not require expensive preprocessing after each rotor position. Any general purpose pre-processor can be used to generate the model in the usual way. Additional reorganisation of the input data structure is carried out within the solver code once only