摘要
级联H桥多电平变频器已经广泛应用于光伏发电、电机调速等领域,但由于各单元独立直流电源参数差异,导致各单元直流电压不均衡。在单元直流电压不均衡时,传统载波移相PWM调制策略存在输出电压低频边带谐波无法消除的问题,从而影响输出电能质量。对传统载波移相PWM调制策略下变频器输出电压进行了傅里叶分析,研究了一种可变移相角的改进型载波移相PWM调制策略,根据不同工况实时改变移相角,从而消除输出电压的低频边带谐波,有效提高输出电能质量。最后,通过样机实验验证了改进型调制策略的有效性。
In practice,the cascaded H-bridge multi-level inverter is one of the most industrially accepted solution for photovoltaic,motor drives and so on,but cell DC voltages of the cascaded H-bridge inverter are unbalance due to the differences among the DC sources of the H-bridge cells.The performance of the conventonal phase-shifted carrier(PSC)PWM is poor in an unbalanced operation condition,the low-frequency sideband harmonics is not eliminated and the quality of the output voltage degrades.In this paper,a simplified Fourier analysis of the PSC-PWM is presented .In addition,a modification of the conventional modulation method is studied where the angle to be applied to the PSC-PWM is variable and calculated in real time depending on the operational conditions.This method improves the quality of the output power by eliminating the low-frequency harmonics.Finally,the experimental results are presented to demonstrate the good performance of the proposed modulation method.
作者
赵慧
李海胜
ZHAO Hui;LI Haisheng(Vehicle Engineering Department,Zhengzhou Railway Vocational and Technical College,Zhengzhou 451460,China)
出处
《电子器件》
CAS
北大核心
2019年第3期595-599,共5页
Chinese Journal of Electron Devices
基金
河南省高等学校重点科研项目(18A580008)
