Sensorless Vector Control of Permanent Magnet Motors Using Observer-Based Adaptive Estimation Techniques

Abstract

Occurring widely in modern highly-performance drive systems like robotics, electric vehicles, aerospace mechanisms and high precision manufacturing equipment, Permanent Magnet Synchronous Motors (PMSMs) are selected because they operate with a high degree of efficiency, are highly compact, high density of torque and better dynamic response. Conventional PMSM drive Mainstream PMSM drive systems would have the requirement of mechanical sensors, like encoders or resolvers, to obtain measurements of the rotor position and speed in order to employ the strategy of vector control. Use of such sensors, however, costs the system more, decreases reliability and adds complexity to the hardware especially in harsh industrial environments where sensors can fail because of vibration, temperature or electromagnetic interference. To overcome these shortcomings sensorless control methods have been developed as a useful alternative, such that the position and the speed of the rotor are determined by measuring the electrical quantities instead of the physical ones. This paper is an investigation on a sensorless approach to the control of PMSMs using observer-based adaptive estimation methods in order to have a correct estimation of rotor position and speed even without mechanical sensors. The approach proposed will combine a model-based state observer with an adaptive parameter estimation with an aim of raising the quality of estimation when the parameters vary, when subjected to load disturbances and changing operating environments. This control system is a hybrid of field-oriented control (FOC) and a nonlinear adaptive observer that allows accurate decoupling of the torque and flux components without compromising the quality of speed estimation at a large operating range. Simulation and experimental analysis of the implemented control strategy under various operating conditions are used to assess the performance of the proposed control strategy. These findings indicate that there is better estimation accuracy, quicker dynamic response, and smaller steady-state error than the traditional sensorless methods. All in all, the proposed approach is a valid, efficient, and economical solution of high-performance PMSM drive usage in industrial automation and electrical mobility systems.