A Novel Time Varying Dynamic Modeling for Hysteresis Motor

Hysteresis motors are used in special applications such as gyroscope, centrifuge, and machine tool spindle drives due to their unique features such as synchronism, self-starting and developing smooth torque. Dynamic modeling of hysteresis motors is essential to predict of the transient performance, studying the dynamic stability and development of modern closed-loop control and estimation strategies. This paper develops a new dynamic modeling for a high-speed, circumferential-flux type hysteresis motor in synchronous dq reference frame. Major previous models use fixed parameters for rotor’s equivalent circuit parameters corresponding to the major B-H loop of rotor material, whereas operational B-H loop is significantly affected by stator voltage and load torque. In this paper, a time varying dynamic model is developed, in which the parameters of the equivalent circuit of hysteresis rotor material are adjusted based on operational B-H loop. For this purpose and based on elliptical assumption for B-H loops, the hysteresis lag angle β is updated due to the applied stator voltage and available load torque. Developed mathematical model satisfies many theoretical aspects of hysteresis motor behavior in transient and steady-state situations. The model offers a tool for studying the start-up of hysteresis motor, change of stator voltage, variation of load torque, frequency tracking for variable-speed applications and transient-state response to design parameters. Some simulations are provided to demonstrate the validity of developed model in Matlab/ Simulink environment and are verified via some experimental results. Proposed results verify the advantages of this model rather than previous works.