级联式电力电子变压器的主动非均衡功率控制

电力电子变压器是交直流混合配电网的关键设备,为提高级联式电力电子变压器轻载运行效率,文中结合混合脉宽调制技术的非均衡特性,提出一种基于功率主动非均衡控制的效率优化策略。通过输入级级联H桥变换器在混合脉宽调制下的损耗分析以及隔离双向DC/DC变换器的损耗分析,建立了级联式电力电子变压器运行效率模型,据此分析各单元功率非均衡分配以提升整体运行效率的可行性。对混合脉宽调制下各单元功率稳定运行范围进行了推导,并提出适用于系统轻载效率优化的功率主动非均衡控制策略。最后,通过实验对所提控制策略与传统功率均衡控制进行了对比验证,结果表明所提功率非均衡控制可降低轻载条件下的系统损耗,提高电力电子变压器的整体效率。

Active Unbalanced Power Control of Cascaded Power Electronic Transformers

Power electronic transformers (PETs) are the key equipment in AC/DC hybrid distribution network. In order to improve the operation efficiency of cascaded PET under the condition of light-load, this paper proposes an efficiency optimization strategy based on active unbalanced power control, which utilizes the unbalanced characteristics of hybrid pulse width modulation (HPWM) technology. By analyzing the power losses of both cascaded H-bridge converter with HPWM and isolated bidirectional DC/DC converter, the operation efficiency model of cascaded PET is established. Based on the efficiency model, the feasibility for improving the overall efficiency of PET through unbalanced power distribution of each module is analyzed. The power stable operation range of each unit with HPWM is derived, and the active unbalanced power control strategy suitable for system efficiency optimization under the condition of light-load is proposed. Finally, the validation of the proposed strategy in comparison with the traditional power balanced control is confirmed by experiments, and the results show that the proposed unbalanced power control can reduce the power loss under the condition of light-load and improve the overall efficiency of PET.