采用特定消谐PWM的三电平AFE系统设计

Three- level Active Front- end System Design Using Specific Harmonic Elimination PWM

在三电平有源前端(TLAFE)整流器上实现了特定消谐脉宽调制(SHEPWM)。介绍了SHEPWM方法的原理;给出了TLAFE的电压、电流双闭环控制结构;构建试验样机系统,对理论分析做了试验验证。试验结果表明,在试验条件下,采用SHEPWM调制的TLAFE系统,其输出电压谐波主要分布在23次及以上。配合适当设计的输入滤波器,在网侧电流性能接近的情况下,SHEPWM所需滤波器无功器件显著小于传统载波PWM,有效降低了系统的成本和体积。

Specific harmonic elimination PWM （SHEPWM）was realized in three-level active front-end（TLAFE） converter.Principal of SHEPWM was introduced, double closed loop structure for voltage and current control of TLAFE was demonstrated, and experimental set-up was built to verify theoretical analysis. It can be seen from the experimental results that low order harmonics in output voltage of TLAFE using SHEPWM are reduced, although the harmonics with their order equal or greater 23 are comparatively significant. As a result, with appropriate designed input filter, SHEPWM requires less reactive components than traditional carrier PWM to obtain nearly the same grid current, which lowers cost and size of the system.