Hunting in hysteresis motors, impact of supply

Hunting in synchronous motor is the continuous speed oscillation with a frequency around 3 to 5 Hz which arises from voltage or load distortions. This oscillation descends with exponential trend-line to steady state relative lower amplitude. This paper presents an investigation of hunting when a synchronous hysteresis motor is supplied with non-ideal input voltage sources. For studying of machine performance including hunting oscillations, both dynamic and static models of a hysteresis motor are implemented. Performances of the hysteresis motor are studied when the machine is supplied by harmonic content and unbalanced voltage sources and also during short term and long term over voltage operating conditions. The results presented in this paper show that these supply power quality problems in addition of many known undesirable effects on the machine performances may also intensify the hunting oscillations.