| 摘要: |
| 针对最近电平调制策略在电压等级不高且电平数目较少情况下产生的阶梯波在逼近正弦调制波时存在较大拟合误差的问题，提出了一种复合调制策略；首先采集NLM产生的阶梯波与调制信号之间的误差作为阶梯调制信号；然后结合载波调制原理，将阶梯调制信号与幅值相等、相位依次偏移的三角载波信号比较，基于面积等效原理产生一组PWM脉宽调制信号；最后将其与阶梯波信号叠加，最终形成驱动信号；同时改进了传统均压算法来降低系统的开关频率；通过Simulink中搭建的MMC仿真验证，复合调制下既保证了输出电压波形质量，也降低了系统开关损耗和电流总畸变率，而且改进的均压算法对子模块电容电压波动情况能够有效抑制，提高了MMC系统转化效率。 |
| 关键词: MMC 复合调制 子模块均压控制算法 |
| DOI： |
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| School of Electrical and Information Engineering,Anhui University of Science and Technology, Anhui Huainan 232001,China |
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LI Deng -kui,ZHANG Dong
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School of Electrical and Information Engineering,Anhui University of Science and Technology,Anhui Huainan 232001,China
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| Abstract: |
| In order to solve the problem that the stepped wave generated by the recent level modulation strategy has a large fitting error when approaching the sinusoidal modulation wave when the voltage level is not high and the number of levels is small, a compound modulation strategy is proposed. Firstly, the error between the stepped wave generated by NLM and the modulation signal is collected as the stepped modulation signal. Based on the principle of carrier modulation, a set of PWM pulse width modulation signals is generated by comparing the step modulation signals with triangular carrier signals whose amplitude is equal and phase is shifted sequentially. Finally, the step modulation signals are superimposed on the step modulation signals to form the driving signals. At the same time, the traditional voltage equalization algorithm is improved to reduce the switching frequency of the system.The simulation results of MMC built in Simulink show that the quality of output voltage waveform is guaranteed, the switching loss and total current distortion are reduced, and the improved voltage equalization algorithm can effectively suppress the voltage fluctuation of sub module capacitors and improve the conversion efficiency of MMC system. |
| Key words: MMC compound modulation sub module voltage equalization control algorithm |
