Multiple reference frame analysis of a multistack: variable-reluctance stepper motor

A multistack variable-reluctance stepper motor is analyzed using the concept of multiple reference frames. The average-value model developed is shown to approximately predict steady-state and dynamic operation of this device. Moreover, the state variables of this model are constant in the steady state. Therefore, the differential equations which describe this model can be linearized whereupon an eigenvalue analysis can be used to investigate dynamic instabilities. It is shown that this approach can be used to approximately predict the occurrence of parametric instability which heretofore has not been achieved using an eigenvalue analysis. The average-value model established in this paper should serve as a unique tool to aid in the design of the machine as well as the controls associated with the electronic drive system