用于贯通式牵引供电系统变换器的谐波分析

The Harmonic Analysis of the Three-phase to Single- phase Converter Applied to the Advanced Co-phase Traction Power Supply System

研究目的:基于三相—单相变换器的贯通式牵引供电系统可以彻底取消牵引网电分相及其相关装置,并可极大地改善三相电网和牵引供电系统电能质量。本文针对用于该系统的核心设备三相—单相变换器的各部分谐波进行了理论计算,并利用Matlab/Simulink搭建了仿真模型,并完成了仿真验证。研究结论:(1)采用SPWM调制的单相变换器,若开关频率远高于牵引网电压频率,则可抑制和消除高次谐波,使输出单相电压谐波主要集中在3、5、7、9等低次谐波,但单相逆变器从直流侧吸取的电流必然含有二次谐波;(2)采用SVPWM调制的三相整流器,三相电网侧输入的电压中不含3倍频的谐波,输入电流总谐波随滤波电感的增大而降低,并随直流电压的增大而增大;(3)给出各部分谐波幅值的计算方法,可通过计算机编程计算得出;(4)本文的研究结论可为进一步研究贯通式牵引供电系统产生谐波、谐振及其抑制和交直交变换器谐波特性提供理论依据。

Research purposes： The electric phase separation of the electrical railway can be completely cancelled in the advanced co - phase traction power supply system, which is based on three - phase to single - phase converters, and the power quality of the system can be improved greatly. Each part of the harmonic waves of the three - phase to single - phase converter, a primary structure of the system, is calculated in detail in this paper. A simulation model is built up through Matlab/Simulink to verify the theoretical calculation. Research conclusions：（ 1 ） When adopting SPWM modulation to the inverter and the switching frequency is far higher than the basic frequency, the output harmonic voltage is reflected on mostly in low - order harmonics, especially 3th, 5th, 7th, 9th. However the current absorbed from the DC side definitely contains a 2 -order harmonic. （2） When adopting SVPWM modulation to the rectifier, the input voltage contains non 3 - times frequency of harmonic and the input current is influenced by the filter inductance and the DC voltage, namely, THD of the current rises along with the increasing DC voltage and drops with the decreasing inductance. （3） The proposed theoretical calculation in this paper can be easily achieved with a computer program. （4） The paper can provides the theoretical calculation evidence for the possible harmonic, resonance problems and their suppression that may occur in the further research of the advanced co -phase traction power supply system, and also for other AC -DC -AC converters.