Research On Zero Drift Compensation For Sensorless Operation Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)with high power density and excellent performance has been widely used in industrial manufacturing,transportation and household appliances.In order to reduce the size of the control device,reduce the cost and the reliability of the system,it is necessary to abandon the position sensor to realize the sensorless control of PMSM.At present,the flux observer method is one of the most commonly used and easy to implement in sensorless control strategy of PMSM.However,in flux observer method,there is a pure integration link in flux observation.Due to the influence of sensor error or dead time,there will be a certain amount of zero drift.Pure integration will make the zero drift accumulate to the integral saturation,which will cause flux observation error.Therefore,it is necessary to choose a proper method to deal with this problem.Taking the surface mounted permanent magnet synchronous motor as the research object,the zero drift based on flux observation method is studied The main work includes:Firstly,The mathematical model of PMSM is built,the principle of vector control is introduced,the basic principle and algorithm of SVPWM are summarized,which lays a theoretical foundation for the follow-up study of zero drift compensation of permanent magnet synchronous motor;Secondly,To solve the problem of the poor dynamic performance of the traditional flux observer based on the low-pass filter method,a flux observer based on the improved low-pass filter method is proposed.The positions of the low-pass filter module and the phase amplitude compensation module are exchanged,which effectively improves the dynamic performance of the permanent magnet synchronous motor control system,The effectiveness of the proposed method is verified by experiments and simulations;Third,In order to solve the problem that the traditional filter flux observer can not completely eliminate the zero drift,two new methods based on the high-order filter are proposed.The first is a new method that the double low-pass filter replaces the pure integral to solve the stator flux.In this method,two low-pass filters with different dielectric frequencies and proportional coefficients are used to reduce the zero drift after filtering the input back EMF.The second is the stator flux observer based on band-pass filter,which can eliminate DC bias.After theoretical derivation,the amplitude and phase compensation methods of the above two higher-order filters are given,which effectively improves the flux observation accuracy and rotor tracking accuracy,The effectiveness of the proposed methodis verified by experiments and simulations;Fourth,To solve the problem of complex parameter setting and complex compensation of phase and amplitude,a black box method is proposed to solve the problem of zero drift in flux observation of permanent magnet synchronous motor.The black box method designed in this paper is a flux observer based on cloud model zero drift compensation.After detailed analysis and introduction of the cloud model algorithm,the cloud model algorithm is integrated into the flux observer to accurately estimate the stator flux in a wide speed range(especially at low speed),and achieve high-performance control of permanent magnet synchronous motor,The effectiveness of the proposed method is verified by simulation;The research of this paper greatly enriches the method of eliminating zero drift in the sensorless control algorithm of PMSM,which has certain guiding significance and reference value for the design of variable frequency drive in practical engineering.