高精度宽频带逆变器输出直流飘移控制的一种新方法

逆变器驱动纯电感负载时,很低的直流漂移电压就会产生很大的直流电流.很难从数百伏的交流电压中检测出mV级的直流电压分量.采用对交流输出电流进行检测和调偏控制的方法解决了这一难题.对输出交流电流进行双向分离、分别采样和滤波,然后通过两个分量的对比来进行调偏控制,有效地提高了检测和控制精度.同步采样和低频采样拍频会带来严重的检测误差,采用多重互质采样频率同时采样的方法有效地缓解了这一矛盾.仿真和实验结果均证实了上述方法的有效性.

A Novel Scheme of Output DC Drift Control in Wide-Band High-Precision Inverters

Aiming at the special requirement to compensate the output DC voltage drift of a wide-band and high-precision power inverter with an inductive load, in which a very small DC voltage drift will result in a very large DC current component. A novel control scheme is introduced to overcome this problem. Detecting a DC voltage in mV level from an AC voltage in several hundred volts level is difficult, and this problem is solved by detecting the corresponding current instead in the load. Both of the positive and negative direction components of the current are separated, and then sampled and filtered respectively, finally a fine-controlled DC offset is applied to compensate the output dc drift according to the comparison of the two DC currents parts. The inverter output frequency ranges randomly between 3 to 5000Hz, if both of the sample frequency and the detected signal frequency are synchronized or adjacent a serious sample error will be produced. A set of several relatively prime sample frequencies are simultaneously used to sample the two separated components respectively, so that the problems are solved better. Theoretical analysis and simulation and experiment results are given in this paper.