Investigation Of Sensorless Control System For Permanent Magnet Synchronous Motor Based On High Frequency Signal Injection Method

Electric Vehicle (EV) provides an effective way to cope with the energy crisis as well as environmental pollution problem, thus, it has gradually become an important direction for the development of transportation vehicles. Due to several advantages such as small cubage, great power density and high efficiency, Permanent Magnet Synchronous Motor (PMSM) is widely used in drive system of EV. To further reduce the cost and complexity of drive system, sensorless control strategies for PMSM need to be proposed urgently. Focused on those issues, a sensorless control system for PMSM based on high frequency signal injection method is designed and investigated in this thesis.First, basic principles of rotor position estimation using high frequency signal injection method are analyzed. System simulation model is established with Matlab/Simulink secondly. Then, the whole software architecture for the sensorless control system is designed and subsequently developed based on TMS320LF2407 DSP. Furthermore, key techniques such as software implementation and selection of parameters are discussed in details to construct the delay-filter and Phase Locked Loop (PLL). After that, an experimental platform for an insert-type PMSM is established, based on which the proposed sensorless vector control approach is implemented and detailed experimental results are obtained. At last, various factors leading to estimate errors are analyzed, including multiple saliencies, inverter nonlinearity, current regulator, using filter. The analysis mainly focuses on how to decouple the stationary saliency to alleviate error fluctuation and how to tune the PID parameters of current regulator to reduce the stationary error.Both simulation and experiment results demonstrate that the presented sensorless control system for PMSM can estimate the rotor position efficiently at wide speed-range, even at zero-speed operation. Furthermore, this technique has significant advantages such as strong robustness to parameter variation, easy implementation in practice, therefore, the technique can be applied to improve the performance of drive system of EV from a engineering point of view.