Research On Fault Diagnosis Of Urban Transit Vehicle’s Ac Drive Main Circuit

Today, AC drives is widely used in urban transit of China. The traction system is the core of the train’s motive power to the urban vehicle, and the most important element of the traction system is the inverter, because it directly influenced the operation performance of the vehicle. So it is really necessary researching on the diagnostic of the fault of the inverter.This paper firstly analyze the principle and structure of the main circuit of the AC drives of the urban railway vehicle, and put an emphasis on the introduction of the inverter’s principle and using method,then introduced briefly the common faults of the main circuit. This paper mainly reasearch on the faults of the power switch device of the inverter, built the sinusoidal PWM control two-level inverter simulation model based on OrCAD/PSpice, analyzed and researched the faults of the power switch device, and two diagnosis method is given.The first fault diagnosis method made classifications on the characteristic of the output current’s and voltage’s value when the inverter failed, based on the same fault diagnosis standard, and established the fault diagnosis table. We can determine the fault types based on the table when the inverter failed. The second approach is to combine the inverter’s output current waveform of normal state and fault state, and we will find that each waveform graph corresponding the unique fault state. Then the paper made a discrete data processing for these waveforms, and came to a conclusion that each group datas corresponding the unique fault state, these datas are the standard for diagnosing the inverter fault type. When the train is on actual running, the inverter fault happens, then we make the same processing of the inverter’s output datas as the paper did, then compared them with the standard datas, which group datas get the minimal disparity that their corresponding fault state is the failed type we want to find. The diagnosis methods can make a effectively diagnosis for the inverter’s failure.Based on the work that have been done, this paper briefly designed and analyzed the main circuit fault diagnosis expert system, provided a new thought for the fault diagnosis of AC drive of the urban vehicle.