Research on multi-objective optimal modulation technology of five-level ANPC converter
In view of the problems of low DC-side voltage utilization rate of SPWM modulation strategy,complex calculation of neutral point voltage control,and difficulty in digital implementation of SVPWM for the existing five-level active clamped converter,a new SPWM modulation algorithm with multiple opti-mization goals of high voltage utilization rate,neutral point voltage balance,stable floating capacitor volt-age,and small common-mode voltage was studied.Firstly,by studying the intrinsic relationship between SVPWM and SPWM,SVPWM was equivalent to PD-SPWM.Then,the common-mode voltage suppres-sion boundary that does not affect neutral point voltage balance was analyzed,and the low-amplitude com-mon-mode voltage vector space of the five-level converter was reconstructed.The method of injecting ze-ro-sequence voltage to freely select switching sequences and switching the equivalent PD-SPWM types in real time was used to achieve the multi-objective optimization.Finally,an experimental prototype was built,and simulation and experimental means were used to verify the multi-objective optimization algo-rithm.The experimental results show that the common-mode voltage amplitude is reduced by about 32.8%while ensuring neutral point voltage balance and stable floating capacitor voltage,which demon-strates effectiveness of the optimization.
five-level active neutral point clamped(5L-ANPC)convertermulti-objective optimizationnew modulation algorithmfloating capacitor voltage balanceneutral point potential balancecommon mode voltage rejection
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