Thermal investigations for a three-phase AC-to-DC PWM converter

The applied control strategies use all the allowed switching operations of the semiconductor devices such that the converter has a line-friendly performance. High dynamic and satisfactory steady-state performances of the converter were obtained. The authors analyse the effect of different PWM methods on the thermal conditions of the IGBT converter. A complex digital computer program was implemented with the object of the instantaneous and steady-state temperature computing for the semiconductor devices. Three modulation methods, symmetrical sinusoidal, Hanning and 60 degrees flat-top modulation, are compared and different power semiconductors, heat sinks and cooling methods can be taken into account. Details are presented about the thermal models, the mathematical apparatus and the programs. Comparative diagrams are prepared with the computed results. Consequently, the selection of the appropriate modulation method, from thermal point of view, becomes possible. The comparison result is also presented.