针对三电平中点钳位型NPC(neutral point clamped)变换器开关频率提高导致变换器电流纹波与电磁干扰噪声增大的问题,提出1种基于电流纹波预测的变开关频率调制策略,以降低三电平NPC变换器电流纹波、谐波噪声及电磁干扰噪声.根据电流纹波的要求计算出开关周期与采样周期并合成最新的开关周期,形成反馈,从而实现变频调制.使随机周期分布在期望周期的周围,从而使变换器的谐波噪声和电磁噪声更加均匀地分布在较宽的频段上,以达到减少变换器电磁噪声的目的,并改善输出电感上的电流纹波.相关仿真及实验结果表明,相较于传统的调制策略,所提调制策略共模噪声降低了约20 dB/μV,差模噪声降低了约10 dB/μV,其输出电感电流纹波幅值也有相应的减少.
Abstract
Aimed at the problem that the converter current ripple and electromagnetic interference(EMI)noise will increase due to the increasing switching frequency of a three-level neutral point clamped(NPC)converter,a variable switching frequency modulation strategy based on current ripple prediction is proposed to reduce the current ripple,harmonic noise and EMI noise of the three-level NPC converter.According to the requirements of current ripple,the switching cycle and sampling cycle are calculated to synthesize the latest switching cycle and form feedback,so as to realize variable frequency modulation.The random cycle is distributed around the expected cycle,so that the harmonic noise and electromagnetic noise of the converter are more evenly distributed in a wide frequency band.As a result,the electromagnetic noise of the converter is reduced,and the output inductance current ripple is improved.The relevant simulation and experimental results verified that compared with those under the traditional modulation strategy,the common mode noise was reduced by about 20 dB/μV under the proposed modulation strategy,the differential mode noise was reduced by about 10 dB/μV,and the amplitude of output inductance current ripple was also reduced accordingly.
关键词
三电平中点钳位型变换器/电流纹波预测/电磁干扰/谐波/随机SVPWM策略
Key words
Three-level neutral point clamped(NPC)converter/current ripple prediction/electromagnetic interference(EMI)/harmonic/random SVPWM strategy
维普
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