高频SiC单相逆变器调制策略研究
郭小强，杨勇，张纯江
燕山大学电气工程学院 秦皇岛 066004
Email：gxq@ysu.edu.cn
摘 要 逆变器高频运行时，开关损耗和死区影响问题更加突出。如何减小高频开关损耗，同时消除死区的影响是逆变器高频运行需要解决的关键问题。本文以高频SiC单相逆变器为研究对象，针对传统双极性调制存在的问题，设计了一种改进调制策略，利用SiC开关器件并联二极管的续流特性，在半个工频周期内将2个开关一直处于关闭状态，不仅减小了高频开关损耗，而且避免了桥臂直通的风险，无需加入死区，消除了死区引起的负面影响，最后搭建了高频SiC逆变器进行了实验研究，结果验证了设计方案的有效性。
关键词 单相逆变器; 调制策略；高频开关；碳化硅器件 中图分类号：TM464
Modulation Strategy for High Frequency SiC Single Phase Inverter
（Department of Electrical Engineering, Yanshan University, Qinhuangdao, 066004, China）
GUO Xiao-qiang, YANG Yong, Zhang Chunjiang
Abstract：The switching loss and effect of dead time are more severe when the inverter operates in a high-frequency way. Therefore, one of the most important issues is to reduce the switching loss and mitigate the effect of dead time. The high-frequency SiC single-phase inverter is investigated in this paper. Considering the limitation of the conventional bipolar modulation, an improved solution is presented. It utilizes the freewheeling behavior of anti-parallel diode, and two switches are off during the half cycle. In this way, the switching loss is reduced. Furthermore, the dead time is not needed any longer and its negative effect is eliminated. Finally, the experimental tests are carried out on a SiC inverter. The results verify the effectiveness of the proposed solution. Keywords: Single-phase inverter; modulation strategy; high-frequency switch; SiC devices
1．引言
随着宽禁带半导体技术的飞速发展，高频电力电子功率变换技术得到了国内外工业界和学术界的广泛关注，应用前景广阔[1-2]。对于单相逆变器而言，系统高频运行时，开关损耗和死区影响问题更加突出。如何减小高频开关损耗，同时消除死区的影响是逆变器高频运行需要解决的关键问题。实际应用中，开关器件开通或者关断都需要一定的时间。为了避免桥臂开关器件同时导通造成短路过流，必须加入死区时间。然而加入死区会产生死区效应，导致输出电压出现低次谐波畸变，直流电压利用率降低等问题。文献[3]通过调节扰动观测器得出扰动电压来获得死区补偿时间。