Research On Sensorless Control Strategy Of PMSM Based On An Improved Sliding Mode Observer

Permanent magnet synchronous motor(PMSM)has been widely used in various fields due to its simple structure and high reliability.With the development of power electronics technology and digital control technology,and the gradual improvement of new motor control theory,the application of PMSM vector control has been extended from the high performance field to the general driving and special driving occasions.With the widespread use,the application field of PMSM is becoming more and more extensive,and the problem of limited application environment is also becoming more and more prominent.As is known to all,in the application field of household appliances,air conditioning compressor as the heart of the refrigeration system,serve as transport the refrigerant vapor in order to make sure the refrigeration cycle work normal,and refrigeration system needs to be tight encapsulation,mechanical sensors in the complex operating environment are highly susceptible to be damaged,which not only affects the anti-jamming and reliability of the system,but also causes unnecessary maintenance costs.At present,experts at home and abroad not only have improved PMSM's ability to handle complex tasks through semiconductor technology,but also have done in-depth research on how to combine the driver and motor organically together to develop a lower cost and higher performance control system.High-performance sensorless vector control of permanent magnet synchronous motor(PMSM)has become a hot topic in recent years.This paper firstly introduces the domestic and overseas recent research status of permanent magnet synchronous motor and non-sensor vector control.Then the basic structure of PMSM and the basic theory of PMSM vector control system are described in detail,and the model of the system is builted and simulated under the environment of Matlab/Simulink.In this paper,the sliding mode variable structure theory is introduced to realize the speed sensorless vector control system of permanent magnet synchronous motor.The sliding mode observer is designed by using the error between the actual value of motor current and the feedback value.Then the speed and position information of the motor can be estimated by using the induction electromotive force which carries the rotor position information.In order to enhance the robustness of the system and improve the dynamic performance of the system,the phase-locked loop(PLL)technique with good tracking performance is applied to the estimation of rotor position in this paper.The simulation results show that the application of PLL technology weakened the chattering phenomenon effectively.However,the observational results of the system have obvious chattering phenomenon because of the nonlinear characteristics of the sliding mode variable structure itself,which affects the observation accuracy of the sliding mode observer seriously.In this paper,the fractional-order theory and phase-locked loop are effectively fused.The simulation results show that the dynamic performance of the system had improved significantly and achieved good robustness after the application of fractional order theory.