This paper proposes a mathematical model to analyze the resonance and controller design method to suppress the resonance that occurs in slave motor of surface permanent magnet synchronous motors(SPMSM) drive, connected in parallel to a single inverter. the resonance phenomenon is observed when the inverter is controlled by the master slave method, due to the differences in parameters between the two motors and load, during medium and low speed operation.
Based on stability analysis of SPMSMs for torque angle variation, we derives th 6th order nonlinear state space equation according to torque angle variation in SIDM(Single Inverter Dual Motor) structure, using the mathematical model of dual motors. since the 6th order onlinear state space equation analysis is complex, we find the resonance frequency generated by the slave motor, using the characteristic of the secondary system obtained by linearization and model reduction at the steady state operating point. Accordingly, we suppress the resonance phenomenon with lead controller which can increases the damping of system, solving noise problem at high frequency based on resonance characteristic analysis of SIDM structure.
The proposed resonance suppression controller is directly obtained by analyzing the resonance characteristic with lead controller method. therefore, it is possible to fundamentally reduce the effort and the error to set the controller gain. furthermore, the proposed resonance suppression controller is robust to parameter variation by widened stable region due to influence of the added zero point, since it is designed as a lead controller. we confirms the usefulness of stability analysis of SPMSMs and the state space equations model according to torque angle variation analyzed in this paper through simulations and experiments.