级联式电力电子变压器混合脉宽调制谐波分析及均衡控制

发布时间：2018-12-17 15:51

【摘要】：针对基于级联H桥及隔离双向DC/DC变换器的电力电子变压器,提出一种混合工频和高频调制的混合脉宽调制(HPWM)策略。基于波形合成原理及双重傅里叶积分方法,对5电平级联H桥HPWM输出电压频谱表达式进行了理论推导,并与载波移相调制时输出电压谐波特性进行对比。结果表明HPWM输出电压波形仅含有基波与载波边带谐波,在不增加谐波总畸变率的同时可降低系统开关频率。为解决HPWM时各模块开关模式不对称造成的中间直流电压不均衡问题,提出一种前级级联H桥采用开关函数轮换控制与后级隔离双向DC/DC变换器电压反馈加前馈控制相结合的子模块均衡控制策略,有效确保子模块功率及电容电压处于相同的动态变化范围。仿真和实验结果验证了HPWM谐波分析的正确性及所提控制策略的有效性。
[Abstract]:A hybrid pulse width modulation (HPWM) scheme for power electronic transformers based on cascaded H bridges and isolated bidirectional DC/DC converters is proposed. Based on the principle of waveform synthesis and dual Fourier integral method, the output voltage spectrum expression of 5-level cascaded H-bridge HPWM is derived theoretically, and the harmonic characteristics of output voltage are compared with those of carrier phase-shifted modulation. The results show that the HPWM output voltage waveform contains only fundamental and carrier side band harmonics, which can reduce the switching frequency of the system without increasing the total harmonic distortion rate. In order to solve the imbalance of intermediate DC voltage caused by the asymmetry of switch modes in HPWM, This paper presents a sub-module equalization control strategy which combines switching function rotation control with voltage feedback plus feedforward control for the front-stage cascaded H-bridge converter. Effectively ensure that the submodule power and capacitance voltage are in the same dynamic range. Simulation and experimental results verify the correctness of HPWM harmonic analysis and the effectiveness of the proposed control strategy.
【作者单位】：新能源电力系统国家重点实验室(华北电力大学);
【基金】：国家科技支撑计划资助项目(2013BAG24B02) 中央高校基本科研业务费专项资金资助项目(2015XS112)~~
【分类号】：TM41

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