Novel current transducer in a single-phase active power factor correction system

In line-fed converters implementing power factor correction, the current shaping process requires input current sensing, commonly obtained using dedicated power components as shunts or current transformers. This work presents a current sensing circuit applied to active power factor correction with boost topology, which does not use the previous components. The sensing element is an inductor placed in the input filter, needed to comply with electromagnetic emission standards. The operating principle of the proposed sensing circuit is then extensively discussed, and analytical formulation of the frequency response is given for real conditions. The influence of transducer error on the performance of the power factor correction (PFC) system is also analyzed. Theoretical analysis shows that a system with a low total harmonic distortion (THD) can be achieved, and this is confirmed by experiments on a laboratory prototype.