快速陡脉冲重复电场下高频变压器绝缘介质损耗与冲击能量积聚特性  

Dielectric Loss and Impact Energy Accumulation of High Frequency Transformer Insulation under Rapidly Repetitive Pulsed Voltages

作　　者：王威望 李睿喆 何杰峰 张晓彤 李盛涛[1] Wang Weiwang;Li Ruizhe;He Jiefeng;Zhang Xiaotong;Li Shengtao(State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University,Xi'an 710049,China)

机构地区：[1]电力设备电气绝缘国家重点实验室(西安交通大学),西安710049

出　　处：《电工技术学报》2023年第5期1206-1216,共11页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金面上项目(52177025);陕西省自然科学基础研究计划青年项目(2020JQ-045);电力设备电气绝缘国家重点实验室中青年基础研究创新基金(EIPE21314)资助。

摘　　要：电力电子变压器中高频变压器须承受高频非正弦与高温的复杂应力。随着SiC等大功率半导体器件的使用,高频变压器中非正弦方波电压上升与下降沿出现陡脉冲应力,其dv/dt大于10 kV/μs,给高频变压器绝缘可靠性带来巨大挑战。高dv/dt包含大量高频谐波,从而导致绝缘介质损耗明显增加;高频、高dv/dt下绝缘遭受累积性冲击电应力,导致局部电场畸变,引发绝缘局部放电与损伤。该文围绕dv/dt对高频变压器绝缘介质损耗与冲击能量积聚的影响展开研究。采用阶跃响应函数模拟高dv/dt脉冲电压,结合绝缘介质损耗分解与计算,提出了dv/dt与方波电压叠加下绝缘介质损耗的计算方法。结果表明,绝缘介质损耗随dv/dt的增大而增加,绝缘热效应明显增加。根据绝缘在方波交变电场下能量储存和释放特性,分析了高dv/dt下绝缘能量积聚密度pd。采用有限元仿真分析10 kW、10 kHz、1000 V/750 V高频变压器绝缘电场、位移电流与冲击能量密度。结果发现,pd随着dv/dt增加而增大。结合介质损耗计算,研究指出在方波电压高dv/dt处(电压极性反转时),绝缘遭受累积电-热冲击应力,造成绝缘损伤。研究结果为大容量高频变压器绝缘失效与设计提供指导。As a key component,the high frequency transformer(HFT)plays an increasingly important role in voltage isolation and power transfer in solid state transformer(SST).Unlike the power frequency transformer,HFT faces the complex stresses of non-sinusoidal high frequency and high temperature.The fast and steep pulse voltage occurs on the rising and falling edges of a non-sinusoidal square wave voltage in HFTs.Its voltage change rate in the rise period(dv/dt)is higher than 10 kV/μs,which poses great challenges to the insulation of HFT.A High dv/dt voltage contains a large number of high frequency harmonics,resulting in a significant increase in dielectric loss.The insulation suffers from cumulative impact stress at high frequency and high dv/dt voltages,leading to local electric field distortion and partial discharge in the insulation.However,insulation degradation and breakdown is difficult to understand owing to the rapidly repetitive pulsed voltages.This paper focuses on the influence of dv/dt on HFT dielectric losses and impact energy accumulation.Firstly,the step response function was used to simulate a high dv/dt square-wave voltage.It combines with the decomposition and calculation of the dielectric loss.This paper used the complex dielectric parameter,including theε′andε′′of epoxy resin.It depends on frequency and temperature,which can be used in the dielectric loss calculation.The actual square wave voltage can be simulated and treated by frequency domain response.Then a calculation method for dielectric losses with superposition of dv/dt and square-wave voltage was proposed.This equivalent technique simplified the complex multi-frequency dielectric loss calculation.The results indicated that the dielectric loss increases with increasing dv/dt of the square wave voltage,apparently enhancing the insulation heating.The dielectric loss reaches 38.2 kW/m3at 10 kV/μs,which is two times higher than at 0.5 kV/μs.Secondly,a finite element simulation(FEM)of 10 kW,10 kHz,1000 V/750 V HFT was performed,consider

关 键 词：高频变压器 dv/dt 介质损耗 绝缘损伤 能量冲击功率密度 位移电流 

分 类 号：TM433[电气工程—电器]