A new high performance AC to DC rectifier with input power factor correction and harmonic reduction capacity

Abstract

Many conventional switching power supplies in data processing equipment and low power motor drive systems operate by rectifying the input ac line voltage and filtering it with large electrolytic capacitors. Because this process involves both nonlinear and storage elements it has some very undesirable side effects such as the generation of a distorted input current rich in harmonics. The resulting input power factor is also poor (0.6 or less). Further, the input current has the shape of narrow pulses which in turn increases its rms value. The reduction of input current harmonics and improved power factor is important from the energy saving point of view and also to satisfy the forthcoming harmonic standards such as IEC-555. In view of this, this thesis examines the cause and effects of low power factor and harmonic current in single phase rectifiers; provides a thorough review of previous correction techniques; and presents a new approach for ac to dc rectification with input power factor correction and reduced current harmonics. The proposed approach has many advantages which include fewer semiconductor components, simplified control, high performance features, satisfies IEC-555 harmonic current standards, and lends itself to modularization using Smart Power technology. A thorough mathematical modeling demonstrates the operation of the proposed approach. A design procedure along with computer simulation of the proposed technique is described in detail. Application aspects of the proposed approach with hybrid power integrated circuit technology is also detailed. Finally, theoretical results are verified experimentally on laboratory prototypes.