Measurement of stress grading conductivity to 1.6 MV/m and 155 oC Computation of grading power density and temperature rise for PWM waveforms

摘要

The move to PWM-based waveforms with substantial high frequency content results in much greater capacitive currents in the stress grading (SG) material and the conductive armor tape (CAT) which increase power dissipation and electric fields within these elements. Treating this subject numerically is challenging for several reasons, viz., (i) the need to measure SG nonlinear properties as a function of field to at least 1.5 kV/mm over the operating temperature range and (ii) the difficulty of computing steady state temperature rise in a stator bar which results from a continuous PWM waveform. This contribution presents solutions to both problems.