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为提高感应电能传输系统输出功率,满足轨道交通大功率供电需求,该文采用一种基于三重级联的多电平逆变器拓扑结构,通过阶梯波合成消除3次、5次谐波的同时提出采用脉冲密度调节输出功率的方法.首先,建立谐波消除方程,分析在只消除3次谐波的条件下,调节脉宽或移相角调节输出功率时存在的输出功率调节范围小或电压谐波失真值较大的问题.为提高系统工作效率,选择同时消除合成输出电压中的3次和5次谐波,并计算出最优脉宽和移相角.为实现在消除3次和5次谐波条件下输出功率的调节,提出一种基于阶梯波合成技术的脉冲密度调制策略.在研制的基于三重隔离变压器级联拓扑结构的感应电能传输样机上验证该方法的可行性和有效性.测试结果表明,提出的方法可降低谐波在IPT系统中产生的额外损耗,特别是降低轻载时功率器件的开关损耗,进一步提高系统的工作效率.“,”In order to improve the output power of the system,a cascaded inverter based on transformer for inductive power transfer was presented in this paper.Firstly,the harmonic elimination equation was established by using the staircase waveform synthesis technique.Then,the problem that the output power regulation range is small or the total harmonic distortion (THD) value is large when regulating the pulse width or the phase shift under the condition that only the 3rd harmonic eliminated was analyzed.In order to improve the efficiency of the system,3rd and 5th harmonics were eliminated simultaneously,and the optimal pulse width and phase shift angle based on THD was selected.In order to regulate the output power under condition of eliminating 3rd and 5th harmonic,a novel pulse density modulatiorn (PMD) regulation approach based on staircase waveform was proposed in this paper.The feasibility and effectiveness of the proposed method was verified in simulation experimentation with 30kW inductive power transfer (IPT) system.The experimental results show that based on the staircase waveform pulse density control,the output power can be regulated with eliminating 3rd and 5th harmonic in whole load.The additional loss of harmonic and switch loss in light load are reduced,and efficiency of the system is improved.