Technology of Designing Integrator of Rogowski Current Transducer

As the output of Rogowski coil is proportional to the time differential of the current, an integrator is needed to recover original current signal. The designing of ideal analog integrator and improved analog integrator is presented, the related error sources are analyzed, the analog integrator is just suitable for large current measurement at low frequency or small current measurement at high frequency. Then three different digital approaches of designing integrator are given; the error sources related to these approaches are also analyzed, it is proved that digital integrator is applicable for small current measurement at low frequency. As a result, adopting the digital integrator in ADE7759 chip has the best performance and can achieve 0.2 class accuracy.