摘要
Abstract
Objective For the hybrid cascaded H-bridge inverter with a voltage ratio of 1∶1∶2 on the DC side of the three-unit,the inverter can output better power quality under the traditional modulation strategy.However,the low-voltage unit of the inverter will have the problem of unbalanced output power under the full degree of modulation.Based on this,a new hybrid modulation strategy was proposed.Methods Firstly,based on the traditional hybrid frequency modulation strategy,the second layer carrier of the low-voltage unit was reconstructed and the reconstructed carrier characteristics were used to provide the logic signal for the low-voltage unit.Secondly,by logically operating and controlling the pulse signals of the two low-voltage units,the actual driving signal of the low-voltage unit power switching device was obtained,and the pulse signal of the low-voltage unit was redistributed.In order to reduce the switching losses in the high voltage module of the inverter,the step wave modulation method was used for the high voltage unit.Results The simulation results show that the new hybrid modulation strategy can solve the problem of unbalanced output power of the low-voltage unit of the inverter under the full degree of modulation system.It was verified that the new modulation strategy can achieve an approximate 1∶1 output power of the low-voltage unit through experiments.The simulation analysis showed that the value of total harmonic distortion(THD)of inverters using the new modulation strategy was reduced.Conclusion The new modulation strategy can reduce the number of carriers and balance the switching losses.In addition,while retaining the advantages of traditional mixed frequency modulation,it reduces the THD content of the inverter and improves the power output quality of the inverter.At the same time,the problem of unbalanced output power under a full degree of modulation of the low-voltage unit is solved in two carrier cycles.关键词
逆变器/H桥/混合级联/功率均衡/逻辑运算Key words
inverter/H-Bridge/hybrid cascade/power balance/logic operation分类
信息技术与安全科学
