【摘要】：混合頻率載波調(diào)制法可以解決混合級聯(lián)7電平逆變器的功率環(huán)流問題,但其輸出電壓的諧波特性較差。為此,提出了一種改進的混合頻率載波調(diào)制策略,該策略使得高壓單元運行在單極倍頻正弦脈寬調(diào)制(sinusoidal pulse width modulation,SPWM)下,從而提高了高壓單元的等效開關(guān)頻率。此外,對高、低壓單元的開關(guān)策略進行了優(yōu)化改進,減少了開關(guān)次數(shù)。相比于改進前的方法,在高壓單元開關(guān)頻率相同時,其等效開關(guān)頻率可提高1倍,逆變器輸出電壓的諧波將分布在更高的頻段,從而改善了逆變器輸出的電能質(zhì)量,同時消除了功率環(huán)流。由仿真結(jié)果可知,在相同開關(guān)頻率下,改進后的方法使得輸出電壓的較低次諧波由約1 k Hz提高到了約2 k Hz,并且不會出現(xiàn)功率環(huán)流現(xiàn)象。研究結(jié)果對所提出的改進的混合頻率或波調(diào)制策略的實用化有一定意義。
[Abstract]:The hybrid frequency carrier modulation method can solve the power circulation problem of hybrid cascaded 7-level inverter, but the harmonic characteristics of the output voltage are poor. In this paper, an improved hybrid frequency carrier modulation strategy is proposed, which makes the high voltage unit run under the unipole frequency doubling sinusoidal pulse width modulation (sinusoidal pulse width modulation,SPWM), thus increasing the equivalent switching frequency of the high voltage unit. In addition, the switching strategies of high and low voltage units are optimized and improved to reduce the number of switches. Compared with the previous method, the equivalent switching frequency of the high voltage unit can be doubled when the switching frequency is the same, and the harmonic of the output voltage of the inverter will be distributed in a higher frequency band, thus improving the power quality of the inverter output. At the same time, the power circulation is eliminated. The simulation results show that, at the same switching frequency, the improved method increases the output voltage from about 1 k Hz to about 2 k Hz, and there is no power circulation phenomenon. The results are significant for the practical application of the improved hybrid frequency or wave modulation strategy.
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本文編號：2363233