中压三电平并网逆变器断续脉宽调制策略及其输出滤波器优化设计  

Optimized Design of Discontinuous Pulse-width Modulation and Output Filter for Medium-voltage Three-level Grid-connected Inverter

作　　者：任康乐[1] 张兴[1] 王付胜[1] 屠运武[2] 汪令祥[2] 

机构地区：[1]合肥工业大学电气与自动化工程学院,安徽省合肥市230009 [2]合肥阳光电源有限公司,安徽省合肥市230088

出　　处：《中国电机工程学报》2015年第17期4494-4504,共11页Proceedings of the CSEE

基　　金："十二五"国家科技支撑计划项目(2012BAA01B04)~~

摘　　要：在中压大功率并网逆变器中,存在开关频率低、输出滤波器设计困难等问题。采用断续脉宽调制策略(discontinuous pulse-width modulation,DPWM)能在保证开关损耗不变的前提下,有效提高逆变器等效开关频率、降低滤波器设计难度。首先,对6种三电平DPWM(DPWM0、DPWM1、DPWM2、DPWM3、DPWMA、DPWMB)的各自优缺点进行比较分析,结果表明在单位功率因数及较高调制度下,DPWMA兼具开关损耗小、共模电压与谐波畸变低的优点;其次,针对DPWMA调制策略输出谐波相对集中于第一载波带的特性,引入LLCL滤波器拓扑,并基于选频思想提出一种改进阻尼方案,在有效提高载波频率处谐波衰减能力的同时,确保谐振抑制能力且显著降低阻尼电阻损耗;随后,给出了所提滤波器的参数设计原则及其详细流程。对30 k W样机进行实验,实验结果表明,采用该文所提调制策略和滤波器设计方法,逆变器的输出共模电压和并网电流谐波含量能够得到有效降低,同时阻尼电阻损耗较小,有利于减小中压大功率逆变器的网侧滤波器体积与成本,提高系统效率。In a medium-voltage high-power grid-connected inverter, the switching frequency is low and the filter design is difficult. Discontinuous pulse-width modulation （DPWM） can increase the equivalent switching frequency and reduce the difficulty of filter design with the same switching losses. This paper firstly comparatively analyzes 6 kinds of 3-level DPWM （DPWM0, DPWM1, DPWM2, DPWM3, DPWMA and DPWMB）, which shows DPWMA has the best comprehensive performance with small switching loss, common-mode voltage and harmonic distortion. Then, aiming at the output harmonic characteristics of DPWMA, an LLCL filter is adopted and an improved damping scheme is proposed, which can effectively improve the carrier-frequency harmonic attenuation ability and ensure the resonance suppression, meanwhile significantly reduce the damping resistance losses. There with the parameter design principle and process of the filter are given. Finally, a 30kW inverter prototype experiment shows the effective reduction of common-mode voltage, grid-side current harmonic content and damping losses of the proposed scheme, which can reduce the grid-side filter size and cost of medium-voltage high-power inverter and improve the system efficiency.

关 键 词：中压三电平逆变器 断续脉宽调制 LLCL滤波器 无源阻尼 参数设计 

分 类 号：TM46[电气工程—电器]