Abstract
The features of the control systems of temperature of the traction frequency converters consisted of rectifier, capacitor and voltage source inverter for traction rolling stock are discussed. The induction motor is considered as a load for traction frequency converter. The dependence of the number of thermal cycles from semiconductor junction temperature fluctuations before the failure of the semiconductor device are shown. The topology and operation principle of automatic temperature control system of voltage source inverter semiconductor devices of traction frequency converter are developed and described. The system is based on air forced cooling with the use of fan or blower as an executive regulation device. The main feature of the proposed system is the additional reference of switching frequency that allows to reduce the semiconductor temperature fluctuations. The elements of switching frequency control loop are chosen and evaluated, the recommendations on practical implementations are given. Simulation of automatic temperature control system in Matlab with both references of semiconductor junction temperature and its fluctuation was carried out with all essential nonlinearities of induction motors and semiconductor devices taken into account. Results of simulation are included and discussed.
Highlights
Survey of various researches and publications [1,2,3] shows that the main malfunctions and damages of power semiconductor devices at long current loads are caused by processes of thermomechanical aging of solders, defects in contacts between cooling radiators and power semiconductor devices, damages of semiconductor structures caused by significant temperature changes during unregulated cooling
The system has two references: the first one is the semiconductor junction temperature, which delivered by the supply of cooling air, and the second reference introduced by the authors is the semiconductor junction temperature fluctuations, which delivered by the switching frequency of semiconductors
The dependence of the number of thermal cycles from semiconductor junction temperature fluctuations before the failure of the semiconductor device on a logarithmic scale is shown in Fig. 1 [12]
Summary
Survey of various researches and publications [1,2,3] shows that the main malfunctions and damages of power semiconductor devices at long current loads are caused by processes of thermomechanical aging of solders, defects in contacts between cooling radiators and power semiconductor devices, damages of semiconductor structures caused by significant temperature changes during unregulated cooling. Temperature stabilization is necessary to increase the reliability of traction semiconductor converters and their cooling systems, reduce the consumption of electricity or fuel for cooling [6]. In Russia, for a long time, traction static converters of locomotives were carried out with a forced air cooling system. For example, the traction converter of diesel locomotives of the Eurorunner ER20, manufactured by Siemens AG, contains a liquid cooling system. Diesel locomotives of the Evolution (USA) have traction converters with a forced air cooling system. The investigation and development of techniques of temperature control of locomotives traction frequency converters are still relevant and important. The authors of this article lay down the control system of temperature provided control both the average temperature of traction converter semiconductors and its fluctuations
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