电压型变流系统研究

A Study of Voltage Type Current Converter

本变流系统,采用具有辅助可控硅换流的电感储能型逆变电路.这种逆变电路适于调频范围宽的大、中功率的变频系统.其特点是:环流小,换流效率高,适应负载能力强. 可控硅变频技术的中心问题是换流问题,本文对逆变主回路的换流过程进行了分析和探讨。这种逆变电路换流电容储存的能量不是消耗或反馈至电网,而是重新储入换流电容器作为下一次换流能量. 整流主回路采用三相全控桥式电路.电容滤波.当主回路的直流超过某一给定值时,移相角迅速后移,使整流桥工作在逆变状态.从而实现过流和短路保护。

In this system an advanced inductance energy storage inverter with auxiliary SCR for current switching-over is used. This inverter is suitable for frequency converters with wide adjustable frequency range and large or medium power, Its characteristics are: small circular current, high switching-over efficiency and good load adaptability The key problem of SCR frequency converter is current switching- over. This paper has analyzed and discussed exhaustively the switch- ing-over process in the main circuit of the inverter. The energy stored in the switching capacitor is restored for next switching instead of being lost or fedback to the power source. Three-phase fully-controlled bridge circuit and capacitor filter are used in the main rectifier. If the D.C current goes beyond a given limit, the firing angle will shift back rapidly and the rectifier will turn into an inverter, so over-current protection and short circuit protection are achieved.