Endurance of polymeric insulation foil exposed to DC-biased medium-frequency rectangular pulse voltage stress

被引:0
作者
Färber R. [1 ]
Guillod T. [2 ]
Krismer F. [2 ]
Kolar J.W. [2 ]
Franck C.M. [1 ]
机构
[1] High Voltage Laboratory (HVL), Department of Information Technology and Electrical Engineering, ETH Zürich, Zürich
[2] Power Electronic Systems Laboratory (PES), Department of Information Technology and Electrical Engineering, ETH Zürich, Zürich
关键词
Aging; Converter; Dry-type insulation; Electromechanical stress; Inverter; Medium-frequency; Partial discharge; Power electronics; Pulse-width-modulated (PWM); Time to failure;
D O I
10.3390/en13010008
中图分类号
学科分类号
摘要
The endurance of polymeric insulation foil is investigated under a mixed medium-voltage stress (DC + medium-frequency rectangular pulse) by means of accelerated lifetime testing. A dedicated setup is used that allows us to selectively eliminate the known risk factors for premature insulation failure under medium-frequency pulse voltage stress: partial discharges (PDs) during pulse transitions, excessive dielectric heating, and systemic overvoltages. The obtained results on polyethylenterephtalat (PET) insulation foil suggest that the adequate consideration of these factors is sufficient for eliminating the adverse effects of the pulse modulation under the investigated conditions. Indeed, if all mentioned risk factors are eliminated, the time to failure observed under a pure DC stress is shorter than with a superimposed pulse (keeping the same peak voltage). There is then no indication of an additional detrimental "per pulse" degradation process (i.e., the time to failure is not dependent on pulse frequency). In contrast, when repetitive PDs are present, the lifetime under combined DC + rectangular pulse stress strongly decreases with increasing pulse switching frequency. PD erosion of the foil is quantified by means of confocal microscopy, and the applicability of the streamer criterion for predicting PD inception is discussed. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.
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