Joe Chui Pong Liu

A PFC voltage regulator with low input current distortion derived from a rectifierless topology

This paper presents an ac–dc converter topology for realization of power factor correction (PFC) voltage regulators for applications where the mains frequency is high and a low input current harmonic is required, e.g., in aircraft power systems. The proposed converter represents a minimal configuration consisting of two basic converters, which can be systematically derived from a previously proposed general synthesis procedure for rectifierless ac–dc converters. The proposed PFC converter has incorporated a control method which drastically reduces the circulating power and hence raises the efficiency to a level comparable to existing PFC converters. The proposed PFC converter can completely eliminate any crossover distortion, which can be significant for supply systems having a high mains frequency. In addition, the proposed converter allows bidirectional energy flow ensuring all inductors work in continuous conduction mode hence eliminating the distortion due to the abrupt change of dynamic response when the operating mode changes. Analysis and design of the power and control circuits will be given and discussed. An experimental system will be presented for verification purposes.

Common-Mode Noise Cancellation in Switching-Mode Power Supplies Using an Equipotential Transformer Modeling Technique

Electromagnetic interference (EMI) is a significant challenge in the design of high-efficiency switching-mode power supplies due to the presence of common-mode (CM) noise. In many power-supply designs, a variety of noise suppression schemes must be implemented in order to meet EMI requirements. Most of these schemes create power loss that lead to efficiency and thermal issues. In this paper, a transformer construction technique is proposed that effectively reduces the CM noise current injecting across the isolated primary and secondary windings. This technique is based on the zero equipotential line theory. A transformer design with the proposed CM noise cancellation technique can achieve high conversion efficiency as well as substantial CM noise rejection.

Common-Mode Noise Cancellation by an Antiphase Winding in Multilayer Isolated Planar Transformer

Common-mode (CM) noise is always present in switch-mode power supplies. All International Electrical Commission class I appliances must have their chassis directly connected to the earth ground, which provides a low impedance path for CM noise to transfer from primary to secondary via the isolated transformer. A proposed planar transformer construction is analyzed and a comparison of CM noise cancellation performance with wire-wound transformers is presented. Planar transformers are found to have better noise cancellation throughout the conducted electromagnetic interference range, thanks to a better winding plane matching to the primary CM noise source winding plane. A planar transformer with two primary winding planes is investigated and a construction with antiphase winding is proposed for best CM noise attenuation.

Component-Based System for Designing Power Supply of no Expert Knowledge Required

This paper introduces the Component based architecture (CBA) employed in a software to design the switching mode power supply (SMPS). Theoretically, there is a unique mapping between a real converter and its behavior. Based on a known circuit topology, the proper design is underlining in the combination of components and its physical configuration. Neither abstract electrical model nor domain knowledge is expected from the user. Besides, this architecture turns optimizing the abstract parameters into component selection.