Research Of Key Techniques Of PMSM Dirves For Direct Drive Drum Washing Machine

With the improvement of people's life, washing machine has become a necessity in every household. The energy crisis followed with the overwhelming development of society has attracted more and more attention in the 21st century. New requirements such as multifunction, energy saving and low-noise are proprosed in the area of washing machine. Because of high power density, high efficiency, simple structure and other advantages, Permanent Magnet Synchronous Motor (PMSM) is more and more widely used in washing machine.The key techniques in the direct drive(DD) PMSM systems in the drum-washing applications are studied in the paper. The rotor position detection algorithm, FOC strategy and field-weakening control in the dewater mode are researched. The DD PMSM systems which can meet the requirements of both wash and dewater mode is designed based on the 8 bit MCU.Firstly, the control strategy is proposed based on the mathematical model and the working condition of drum washing machine. In addition, the two key techniques of pole position estimation and high speed operation are pointed out.Secondly, as one of the two key techniques in the drum washing machine, the position estimation technique based on three switch hall sensors is discussed in detail. The appropriate position estimation technique is determined based on the simulation results which are obtained from the improved simulation model of the position estimation. An improved method to reduce the estimation error is designed with the consideration of hardware condition. The experiment result shows the advantage and the practical value of the proposed method.Thirdly, the second key technique of field weakening control is deeply analyzed. The normal field weakening control method and the maximum power field weakening method are presented in the paper. Then the paper discusses the influence of the PMSM parameters on the performances of the system. A control system which directly using direct axis current as the control parameter is proposed, the simulation results indicate the feasibility and validity of the new scheme.Finally, the experimental platform of DD PMSM system used in drum washing machine is built based on the XC878. Experiment results show that the pole position estimation and field weakening strategy are both effective. The dynamic and static performance can satisfy the requirements in both wash and dewater mode .