The boost converter’s operation is based on the energy stored in inductor L1 as shown in this drawing. When the Q1 transistor is ON, the current through the inductor is rising, and fly-back diode D1 stops conduction. As soon as the Q1 switch opens, there is no path for the current that was flowing through the inductor, except diode D1, the output capacitor C3 and the load. The D1 diode becomes forward biased and starts conducting since the voltage on its anode is higher than the rectified voltage of the AC source. The voltage across inductance L1 reverses its sign to maintain current flow. This way, both the energy supplied by the AC source and what was previously stored in the inductor are transferred to the load and the output capacitor through diode D1. The input rectified voltage VAC and the output VDC are measured using resistor dividers, while the input current is measured using a shunt resistor. The role of the inductance in this power factor correction topology is essential. The physical size of the inductor increases with the power rating. Component size is one of the main reasons for implementing an Interleave PFC design.