The power converters are mostly prone to frequent failures. One of the major causes for their failures is uneven distribution of power losses among the semiconductor devices. The conventional equal loading bus clamping pulse width modulation scheme guarantees equal loss sharing among the devices when the converter operates at unity power factor (pf). However, when the converter operates at non-unity pf, some of the devices are heavily stressed due to higher loss density, i.e., junction temperatures of some of the devices become higher than the others. This paper proposes four switching sequences based on model predictive control for a grid-connected single-phase H-bridge converter used in various applications including superconducting magnetic energy storage system. In each sector, two switching sequences having different zero vectors are selected alternately. The proposed strategy can achieve balanced loss sharing and almost uniform thermal stress among the devices of the converter under all pf. The novelty of the proposed technique is verified with a scaled-down laboratory test prototype.

中文翻译：

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基于模型预测控制的 H 桥转换器先进开关策略用于 SMES 应用以获得均匀损耗共享


电源转换器大多容易出现频繁故障。其故障的主要原因之一是半导体器件之间的功率损耗分布不均匀。当转换器以单位功率因数 (pf) 运行时，传统的等负载总线钳位脉宽调制方案可保证器件之间的损耗均等。然而，当转换器以非单位pf工作时，一些器件由于较高的损耗密度而承受很大的应力，即一些器件的结温变得比其他器件更高。本文提出了基于模型预测控制的四种并网单相 H 桥转换器的开关序列，该转换器用于包括超导磁储能系统在内的各种应用。在每个扇区中，交替选择具有不同零向量的两个切换序列。所提出的策略可以在所有 pf 下实现转换器器件之间的平衡损耗共享和几乎均匀的热应力。所提出技术的新颖性通过缩小的实验室测试原型得到了验证。