大功率三电平中点箝位变流器损耗特性分析

随着大功率变流器容量的提升，功率器件的损耗也逐步增加，从而导致系统的散热及可靠性问题变得更加突出。本文分析了基于IGCT器件的三电平中点箝位变流器各部分损耗的理论计算方法。考虑高压大电流条件下器件电压及电流谐波含量对损耗计算的影响，本文通过电压及电流瞬时值计算功率器件通态损耗、开关损耗，以及缓冲电路损耗，实现变流器系统损耗的准确计算，为大功率变流器不同拓扑结构和调制策略的效率优化分析打下基础，也为系统散热设计提供参考基准。基于负载功率自循环老化原理，本文通过仿真和实验验证损耗计算模型及仿真平台的正确性和有效性，在工程实践上具有一定的实用性。

The Analysis of Loss Characteristics of High Power Three-level Neutral Point Clamped Converter

With the increase of the capacity of high power converters, the losses of power devices has also gradually increased, resulting in the more prominent cooling and reliability issues of the system. The theoretical method of calculating each part of the losses of three-level neutral point clamped IGCT converter is analyzed in this paper. Considering the impact of harmonic content of device voltage and current on loss calculation under the conditions of high voltage and high current, the conduction and switching losses of the device are calculated through the instantaneous values of voltage and current, as well as the losses of the snubber circuit. The achieve accurate calculation of the loss characteristics of the high-power three-level neutral-point-clamped converter system is given, which lays a foundation for the efficiency optimization analysis of different topologies and modulation strategies of the high-power converter and provides a benchmark for system thermal design. The correctness and effectiveness of the loss calculation model and simulation platform are verified through simulations and experiments, based on the principle of load power self-circulation aging, which have certain practicality in engineering applications.