A new active waveshaping technique to comply with IEC 1000-3-2

A new input current shaper has been recently proposed. Its operating principle is based on the connection of a voltage source and a loss-free resistor (LFR) between the input rectifier and the bulk capacitor in a conventional switching-mode power supply with no power factor correction. Both the voltage source and the LFR are obtained as an additional output from the power converter´s transformer. This additional output is a forward-type one with one extra inductor. The main difference with other input current waveshapers lies in the fact that the filter inductor of the additional output operates in continuous conduction mode, so the current stress in the power transistor is minimized. With the final topology, a good trade-off between capacitor voltage, re-cycling energy and harmonic content can be established in order to comply with IEC 1000-3-2