Improvement Of Traction System Of Permanent Magnet Synchronous Motor For Diesel Locomotive

At present,domestically basically adopts the DC-excited synchronous generator as the traction generator,and the three-phase asynchronous motor as the traction motor is a mature internal combustion AC-DC-AC traction transmission form.With the rapid development of permanent magnet technology,it is equipped with technical preparations for diesel locomotives and is becoming more mature.At present,the electric drive permanent magnet synchronous traction system has been gradually applied in the field of urban rail transit,and the first internal combustion permanent magnet synchronous motor traction system has also been completed on-site debugging.Based on the background of an enterprise’s low-power diesel locomotive permanent magnet synchronous traction drive system,this paper optimizes and improves the traction drive system in view of some problems in the field debugging process.At present,there are two main problems: First,there are defects in the selection of the main circuit of the traction system.The original design of the company used uncontrolled rectification,which caused the intermediate DC link voltage to be approximately proportional to the speed of the diesel engine,resulting in a relatively high traction power required for the locomotive.In a small situation,as the speed of the locomotive increases,it is still necessary to increase the speed of the diesel engine to ensure the weak magnetic field of the system,which cannot guarantee the stability of the operating conditions of the diesel engine and the economy of the diesel engine.Second,during the locomotive start-up phase and when the speed of the locomotive changes rapidly,there is a phenomenon that the diesel engine stops.This paper studies the above two problems and improves the permanent magnet synchronous traction system.First,the network control system of the permanent magnet synchronous diesel locomotive is studied from the two parts of the vehicle network structure and the traction control system network structure.Verify the rationality of the control cycle of the network control system through relevant calculations,and analyze the impact of time delay on the real-time performance of the network control system by means of simulation;second,improve the uncontrolled rectification traction system into a controllable rectification traction drive system,and control the power generation system controller And the control strategy is designed to ensure the same as the traditional diesel locomotive.When the traction handle of the master controller is fixed(that is,the traction power is fixed),the speed and output power of the diesel engine are constant,and at the same time,the motor traction system can be guaranteed in the full speed range.Demand for field weakening;Then,the permanent magnet synchronous motor traction system is improved,and a reasonable control strategy is used to achieve system field weakening so that it has a wider speed range and better dynamic characteristics to ensure the operating requirements of the diesel locomotive.Finally,this paper focuses on the problem of diesel engine holding down,combined with the phenomenon of DC bus overcurrent faults during on-site debugging,and analyzes thereasons for diesel engine holding down due to poor traction motor vector control performance under low load conditions.That is,during the starting phase and when the speed of the locomotive changes rapidly,the adjustment characteristics of the motor traction system are poor,resulting in the overcurrent of the DC bus current,resulting in a sharp change in the output power of the diesel engine under low load,and eventually the diesel engine is stopped.Using Matlab / Simulink software to build an improved permanent magnet synchronous traction drive system simulation model,to verify the rationality of the improved system design,and to verify the cause of diesel engine stagnation.