Output-Voltage-Ripple Injection for Reduction of Input-Current THD in Single-Phase DCM Boost Rectifier

Abstract

Boost type Power Factor Correction (PFC) single-phase rectifier in Discontinuous Conduction Mode (DCM) is simple in terms of modeling and control, such as it operates with a single output voltage control. This structure, in DCM, presents pulsed-input current with peak values that naturally follow the input voltage shape, even without current control. The main components of this current are at the fundamental frequency, third harmonic, and switching frequency. The third harmonic component is the main cause of the Total Harmonic Distortion (THD) in this operating mode. This article approaches the injection of a second harmonic component into the Boost inductor current to reduce the third harmonic of the input current and, consequently, to decrease the THD. The technique is simple to implement and it does not use any current sensor. The injected component is generated from the output voltage ripple, that is, without the need for synchronization nor synthetization of the injected signal in the control. Simulation results show a THD reduction from 29.6% to 2.2%, which can qualify the Boost Rectifier in DCM to be used in low power applications with more rigorous standards.