基于斩波控制的新型励磁系统

Novel excitation system based on chopped wave control

提出一种新型的励磁系统接线形式和调节方式,利用励磁变压器作为励磁机的励磁电源,经静止整流和桥式滤波为励磁机提供励磁电流,取消了副励磁机。在此基础上设计了一种新型的开关式励磁调节器,采用全控型电力电子器件绝缘栅双极晶体管(IGBT)作为开关,应用直流斩波控制技术,克服了传统晶闸管所采用的相控技术中对时序要求严格的缺陷。用Pspice仿真系统分析了占空比分别为0.1和0.5时的输出电压和电流,证实其大小均与占空比成正比,与理论分析一致。在一机组上进行了70%零起升压试验和10%阶跃响应试验,结果表明:采用两机加一变的开关斩波控制的励磁控制方式,解决了自励恒压不稳定的问题,提高了整套装置的稳定性。

An excitation system with novel connection and regulating mode is presented, in which an excitating transformer is used as power source of the exciter,providing exciting current through static rectifier and bridge filter. The auxiliary exciter is thus canceled. Based on that,a novel switching excitation regulator is designed using the fully controlled power electronic device IGBT （Insulated Gate Bipolar Transistor） as the switch. The DC chopped wave control technique is used to release the requirement of strict time sequence in phase control of traditional thyristors. The output Voltage and current at duty ratios of 0.1 and 0.5 are simulated respectively with Pspice and it is proved that they are proportional to duty ratio,consistent with the theoretical analysis. 70 % rated voltage start-up test and 10 % step response test are carried out. Results show that,the switching excitation control scheme with two machines and one transformer solves the instability of self-excited constant-vohage excitation scheme and enhances the stabilitv of the whole device.