Analysis of steady-state operation of a multistack variable-reluctance stepper motor using qd0 variables

An approximate method of calculating the steady-state characteristics of a multistack, variable-reluctance stepper motor operating in the continuous speed mode is developed. The mathematical model of the motor is set forth, and the unipolar inverter drive of interest is discussed. The differential equation which governs the flux linkage is then solved explicitly using numerical integration to evaluate the flux linkage waveform. As an alternative to the direct solution, the Floquet transformation is used to obtain a time-invariant differential equation. The qd0-variables are used with the reference frame fixed in the rotor. This approach provides a means of accurately accounting for the harmonic components of the current. The method is shown to be more accurate than existing approximate methods, with a marked computational advantage over exact methods