Research On Speed Regulation System Of Endless Rope Winch Based On Low-Speed Direct-Connected PMSM

Endless rope winch is one of the key equipments of the auxiliary transportation system in the production of coal mine.It is widely used in equipment and material transportation under the conditions of large inclination,long distance,changeable slope,and large tonnage.This thesis takes the speed regulation system of mining endless rope winch as the research object,and the selected speed regulation scheme is the adaptive MTPA control method of low-speed direct connected permanent magnet synchronous motor driven by four-quadrant three-level explosion-proof frequency converter.Aiming at high reliability,high efficiency and high speed regulation performance,this thesis makes an in-depth study on the mathematical model,key parameter selection,common-mode voltage reduction PWM of three-level explosion-proof frequency converter,and adaptive MTPA control based on online searching the d-axis current of low-speed direct connected permanent magnet synchronous motor for endeless rope winch.Finally,the software and hardware design of low-speed direct connected permanent magnet synchronous motor speed regulation system for endeless rope winch is given and verified by experiments.Firstly,according to the mechanical and operating parameters of endeless rope winch,the design requirements of low-speed direct connected permanent magnet synchronous motor speed regulation system are defined,and the overall scheme is given.The mathematical model of low-speed direct connected permanent magnet synchronous motor speed regulation system based on four-quadrant three-level explosion-proof frequency converter is established,and the calculation method of key parameter selection of explosion-proof frequency converter and permanent magnet synchronous motor is studied.The operation environment of four-quadrant three-level explosion-proof frequency converter is closed and complex.The problems of motor shaft voltage,shaft current,and electromagnetic interference caused by high-frequency common-mode voltage generated by high-speed switching action of power switching devices are the key factors restricting its long-term reliable operation.To solve this problem,this thesis studies a simplified three-level common-mode voltage reduction PWM method based on a new switching sequence,deconstructs the three-level PWM into two-level PWM,successfully simplifies the algorithm,and limits the common-mode voltage amplitude within one sixth of the DC bus voltage by using the two-level common-mode voltage reduction switching sequence to reduce the negative effect caused by the common-mode voltage.The common-mode voltage reduction PWM method is simple to calculate and can realize neutral point potential control.Matlab simulation results verify the effectiveness of the simplified three-level common-mode voltage reduction PWM method.In order to improve the operation efficiency of low-speed direct connected permanent magnet synchronous motor speed regulation system for endless rope winch,an MTPA control method based on online searching the d-axis current is studied.Firstly,the factors affecting the MTPA control accuracy of low-speed direct connected permanent magnet synchronous motor are analyzed.It is pointed out that in addition to the inductance and flux linkage parameters,the orientation angle error of permanent magnet synchronous motor also affects the MTPA control accuracy.To solve the above problems,an initial position detection algorithm based on improved pulse voltage injection method is studied.Combined with relative photoelectric encoder,the orientation accuracy of permanent magnet synchronous motor is greatly improved.An adaptive MTPA control method based on sliding mode extreme search algorithm is designed.By online searching the d-axis current value of MTPA operating point,the robustness of MTPA control is improved,and high-precision MTPA control is realized without accurate motor parameters.Finally,combined with the application conditions of mining endless rope winch,based on the simplified three-level common-mode voltage reduction PWM and the adaptive MTPA control method of low-speed direct connected permanent magnet synchronous motor,the software and hardware design of the prototype are completed,and the above methods are verified by experiments.