恒速运行时交流励磁系统电流线性放大器特性分析

Characteristics of Current-Linear-Amplifier of AC Exciter in Brushless AC Generator at Constant Speed

着重研究了恒速情况下交流励磁系统的电流线性放大器特性的实现问题。作者采用了ａｂｃ坐标系统下的凸极同步发电机的数学模型，对交流励磁机带桥式整流电路进行了精确的计算机仿真分析。结果表明，在恒速运行时，电流线性放大器特性的好坏主要取决于电机的电抗负载因素，以及直轴同步电抗大小。通过合理选择电机参数，交流励磁机的电流线性放大器特性可基本得到实现。这对改善电机性能，减轻调压器负担，提高调压精度等有重大意义。

The characteristics of current-linear-amplifier of AC exciter means that the ratio of excitation currents of main generator and exciter is constant,independent on load and temperature. The characteristics is helpful to reduce the range of excitation current of the exciter. This paper presents the theoretical study of the characteristics of current-linear-amplifier of AC exciter in brushless AC generator at constant speed. A digital simulation of the AC exciter with diode-bridge-rectifier load is done at abc coordicate system. The result shows that the characteristics depend on mainly the commutating reactance-load factor and the direct-axis armature reactance of the exciter,and that the greater these two parameters,the better the current-linear-amplifier characteristics is. The realization of current-linear-amplifier of AC exciter is probable by choosing reasonable exciter parameters. It will contribute the red.ucement of load of voltage regulator,and the improvement of performance and output voltage accuracy of brushless AC generator. The results presented here provide useful design information about AC exciter.