Single phase rectification with active line shaping

Abstract

In this chapter the circuit is analysed using the switching function technique. The object of this exercise is to derive the modulating signal of the semiconductor switch in order to establish unity power factor with no harmonics. From the modulating signal, the switching function can be derived; this is already done in Part 1, Chapter 3. The derived switching function is then applied in order to calculate the inductor current for a set of circuit parameters (L, R and output dc voltage). The input current, current through the switch and capacitor current are also derived. The action of the switch is to create a current through the inductor in the shape of a rectified sine wave. This current is reflected to the input via the bridge and its rectifying switching function F^{t). The reflected current will be a pure sinusoid clean from harmonics and at unity power factor; this is the goal of introducing the boost converter at the dc side of the rectifier. The gain of this exercise is to show that a switching function exists to make this circuit produce the necessary shape of the line current. Since the switching function is directly related to the action of the semiconductor switch, proof of the existence of the switching function is a good indication that the circuit can be implemented. Of course, this circuit is already implemented and is the subject of many research papers. The method though, can be proved useful in new circuits under investigation.