基于罗氏线圈检测法的单相逆变器直流偏磁抑制

摘要

In the full-bridge SPWM controlled single-phase inverter,on the output side is normally a transformer.Therefore,the impact of DC magnet bias upon the transformer and the system should be taken into account.DC magnet bias would lead to transformer saturation,reduce the working efficiency of the system,and even seriously affect system operation in some cases.This paper analyzes the reason why DC magnet bias is caused in the transformer of the single-phase inverter,compares ordinary measures taken against magnet bias,and presents an approach whereby that transformer excitation current is detected through Rogowski coil of external integration,the compensation value is calculated through the closed loop feedback,and a controlling unit is adopted for suppression of magnet bias.This approach has such advantages as simple design and cost saving.Experimental results indicate that the object of effective suppression of DC magnet bias can be achieved.%在全桥SPWM控制的单相逆变器中，输出侧一般接有变压器，因此需要考虑直流偏磁对变压器及系统造成的影响。直流偏磁会导致变压器饱和，降低系统运行效率，有时甚至严重影响系统运行。分析了单相逆变器中变压器产生直流偏磁的原因；对常用的几种抗偏磁措施进行了比较，提出一种通过外积分罗氏线圈检测变压器励磁电流，利用闭环反馈计算出补偿量并加入控制环节抑制偏磁的方法。具有设计简单、节省成本的优点，实验表明可有效抑制直流偏磁。