To solve the problem that the switching devices of cascaded H-bridge multilevel inverter in-crease significantly with the increase of inverter output levels,a new type of multilevel inverter based on power switching device-diode was proposed.The proposed inverter can achieve high quality level output with only a few switching devices,and the topology has low switching loss and high efficiency,which is not only easy to expand,but also effectively avoids problems such as current backflow between cascaded units.Under the pulse opposite disposition PWM,the inverter has the problem of unbalanced output pow-er between units.Based on this modulation strategy and through the derivation and analysis of regional power,a power balance modulation strategy based on partial carrier cycle was proposed,and the univer-sality of the carrier cycle law was verified.The proposed modulation strategy can achieve the output power balance of cascaded units and the average distribution of switching losses within nTo/2 after the carrier is transformed 2(n-1)times while keeping the output voltage waveform quality unchanged,and the power utilization is improved.Finally,the proposed modulation strategy is experimentally verified on the experi-mental platform of the two-unit seven-level inverter.
关键词
新型多电平逆变器/开关损耗/电流倒灌/载波循环/区域功率重组/功率均衡
Key words
novel multilevel inverter/switching loss/current backflow/carrier rotation/regional power recombination/power balance
维普
万方数据