Research On Pulse Rectification Technology For Permanent Magnet Synchronous Motor Traction System Of Diesel Locomotive

At present,most of the diesel locomotive traction power supply systems use electrically excited synchronous generators and uncontrolled rectification of the power supply method,such power supply method will lead to the intermediate DC link voltage and diesel engine speed approximately proportional relationship,such as its application in the diesel locomotive permanent magnet synchronous motor traction system,when the diesel engine low-speed operation,permanent magnet synchronous motor by the weak magnetic limits,resulting in the locomotive speed range is narrow;if you want to improve the locomotive operating speed,can only enhance the diesel engine speed,while causing the diesel engine can not operate according to its economic characteristics curve.To solve the above problems,a new scheme is proposed for the traction power generation system according to the basic needs of diesel locomotives,i.e.the pulse rectification technology scheme for permanent magnet synchronous motor traction system of diesel locomotives,with permanent magnet synchronous generator instead of an electrically excited generator and PWM rectification technology instead of uncontrolled rectification technology,and the permanent magnet synchronous generator and PWM rectification technology are applied to the permanent magnet synchronous motor traction system of diesel locomotives at the same time for the first time.In the thesis research work,starting from the basic idea of PWM rectification technology,firstly,the main circuit of the traction power generation system of diesel locomotive in the new scheme is designed,and the relevant parameters of the system and the selection of key devices are calculated;secondly,for the difference between the PWM rectification technology applied in this system and the general pulse rectification technology in the industrial frequency grid,this paper takes the premise that the voltage of the intermediate DC link in the full speed domain of the diesel engine is stable Based on the principle that the overall efficiency of the power supply system is the highest,the control strategy of controlling the phase difference between the output voltage and current of the permanent magnet synchronous generator at different diesel engine speed is proposed to make the generator power factor the highest and make the system work at the highest efficiency point;according to the control strategy,a controller consisting of phase difference outer loop,voltage outer loop,current inner loop,SVPWM link and PI regulator is designed;also Because of the characteristics of the diesel engine continuously changing in a wide speed range and outputting three-phase alternating current with varying amplitude and frequency,this paper tracks the phase of the generator output voltage and current through the phase-tracking phase-locked loop technique.Through the above work,a complete set of pulse rectification technology schemes for permanent magnet synchronous motor traction systems of diesel locomotives has been formed.Finally,Matlab/Simulink simulation software was used to build a model of an diesel locomotive traction power generation system,and the rationality of the system design was verified through four working conditions: no load,constant speed constant load,constant speed variable load,variable speed variable load,to fit the actual working conditions of diesel locomotive.