Study On Premature Failure Mechenism Of PWM Inverter-Fed Traction Motor

In recent years, railway transportation becomes more and more busy in China, and some lines even operate with overload. Thus, it is promising to develop high-speed railway in China. Traction motor used in high-speed electric locomotive is the necessary equipment which enable railway transportation develops toward high speed with heavy duty. As the key component in AC-drive electric locomotive, the operation performance of traction motor will right influence the stability and reliability of the locomotive.With the development of power electronics technology, AC-drive traction motor is developed into being larger power, small volume, lightweight, and high speed. However, it is found that the premature failure of adjustable speed traction motor is prominent in its operation, which restricts the development of high-speed electric locomotive. And at present, the premature failure mechanism of insulation is not so clear. That's the reason why it is necessary and urgent to study on the failure mechanism of insulation, and then present the countermeasures to motor manufactures to resolve the problem.his dissertation aims to find the failure mechanism of inverter-fed motor. Firstly, analyses the possible insulation influencing factors in PWM inverter, connecting cable and motor respectively, and how each factor influences on insulation. Secondly, discuss the influence of the electrical, thermal and mechanical aging -on insulation degradation. Finally draw the conclusion that partial discharge, dielectric heating and space charge induce the insulation breakdown collectively and fast risetime and high carrier frequency are the primary contributing factors of insulation premature failure.