Simulation and Evaluation of Non-Injection,Voltage Sensing-Based Flux Tracking Self-Sensing for SPMSMs for Zero-to-Low Speeds

Abstract

Simulation model and evaluation of a self-sensing method based on flux tracking using measured phase voltage for motion control in the zero-to-low speed operation range of surface permanent magnet synchronous machines (SPMSMs). The limitation of previous non-injection based self-sensing methods, especially at zero-to-low speed, is an inaccurate voltage reference due to inverter nonlinearities and a back-EMF term which approaches zero frequency as speed does. This research focuses on a thorough investigation of the limitations of back-EMF tracking at zero-to-low speeds with measured phase voltages, using a patented, but relatively undocumented methodology to measure back-EMF at zero-to-low speeds. The induced voltage and current responses to the permanent magnet flux at zero-to-low speeds is modeled and simulated under a variety of conditions in order to determine the optimal position state filter or observer. The resultant motion control system is evaluated via dynamic stiffness and under a set of different conditions of torque load (TL) in order to determinate the limitations of this flux tracking approach. The outcome of this research is an understanding of the effects of bandwidth selection for the PLL and motion and current controllers, an evaluation of the disturbance rejection capabilities of closed loop control at zero-to-low speeds, and a method for using measured stator voltage for enhanced zero-to-low speed position estimation for flux tracking self-sensing methods.