Apparatus for Monitoring Residual Current of Transformer-less PV Inverter

摘要

The present invention calculates a resistance component of a leakage current with respect to a transformer type solar inverter. To do this, the DC component of the leakage current sensed by the ZCT is removed, leaving only the AC component, and the peak value and the phase are obtained through the PLL. Then, the effective value of the AC component is obtained, and then the DC value is added to calculate the resistance component value of the leakage current. It is possible to measure the resistance component of the leakage current generated during the operation of the transformerless inverter to improve safety against system accidents and risk of injury to the user during operation of the inverter.