Subharmonic resonance in stepping motors

A study of the resonance phenomena that can occur in stepping motors operating at pulse rates above the natural frequency is described. This resonant behaviour is distinct from the dynamic instability present at much higher stepping rates. In particular, a resonance oscillation is investigated which occurs when the pulse rate is twice the natural frequency of the motor. A simple analysis is presented to explain the mechanism, and the conditions necessary for such behaviour are determined. The possibility of resonance phenomena due to the nonlinearity of the torque/angle characteristic is also discussed. Experimental and computer predicted results are presented.