The Dynamic Stability of Step Motors

Mid-frequency instability (MFI) generally limits the application of step motors with constant-voltage drive to a speed range well below theoretical limit imposed by inductance, back EMF, and friction torque. Analytical studies MFI in specific motor types configurations have been reported literature, each focused on particular method analysis. The goal this paper is develop single model structure dynamic stability analysis, applicable all motors. To end, generalized n -phase dynamical system broad permanent-magnet hybrid (PMH) variable-reluctance (VR) developed. Beginning physical working from first principles, ( +2) th -order nonlinear time-varying (NLTV) state equation Next, Park transform for applied, resulting fourth-order NLTV set -2 first-order LTI equations. then solved at constant linearized about solution, linear time-invariant (LTI) equation. Finally, performance are determined examining eigenvalues system. scope parameterization includes: type (PMH or VR); number arrangement poles, stator teeth, rotor teeth; electrical phases = 2 odd); magnetic circuit (uni-phase multi-phase); winding configuration; variable xmlns:xlink="http://www.w3.org/1999/xlink">current xmlns:xlink="http://www.w3.org/1999/xlink">flux linkage ). Examples given illustrate computer simulations used verify results.