Hybrid Energy Transfer Power Factor Correction AC/DC Converters With Improved Efficiency

The University Of Central Florida Board Of Trustees, Orlando FL

Investigators

Abstract

Power electronics technology is widely used in various industrial sectors and has recently been identified by the Office of Science and Technology Policy as critical for the future growth of the U.S. economy. Today innovations in electronic products are progressing at an unprecedented rapid pace. However, power electronics technology has not kept pace with the growth in low and medium power electronic industries. With this proposal, the PIs seek to improve the power supply performance by exploring new design techniques to develop a family of efficient, high-frequency, low and medium power AC-DC converters with reduced cost and improved reliability, and still achieve near unity power factor. This effort targets future stringent power requirements for high-speed microprocessor used in next generation computer and communication systems. The objective of the proposed research is to develop novel hybrid energy transfer AC-DC converters improved efficiency and increased reliability and provides Power Factor Correction (PFC). In a traditional single-stage AC/DC-PFC scheme, the converter normally operates in Discontinuous Conduction Mode (DCM) and has the advantages of simplicity, low cost and high reliability, while less efficiency due to its inherent high voltage and current stresses. Moreover, it cannot achieve simultaneously, the desired input performance in terms of low power factor and harmonics, and output performance in terms of voltage ripple and regulation capabilities. The two-stage scheme can achieve unity power factor and higher output performance, but at the expense of high component count and increased system complexity. This in turn increases cost and degrades the reliability of the whole power electronic system. In both single-stage and two-stage AC/DC converters, the power is processed twice as all the transferred energy would once store in an intermediate bulk capacitor. Here, we propose a novel method that allows parallel path of energy transfer to minimize power-processing times and to improve converter efficiency and reliability. A lion share of the input power directly transferred to the output without going through the input current shaping stage while the converter remains a near-unity power factor. Furthermore, considering the operation irrelevance of PFC stage and DC-DC stage in two cascade stage converters, the PIs also propose a novel concept to improve the efficiency by linking PFC stage with DC-DC stage to provide soft-switching conditions for the PFC stage or DC/DC stage without adding any auxiliary switch. During the projects two-year period, the following major tasks will be carried out: 1) Investigate the limitations of improving efficiency in existing PFC- AC/DC converters. 2) Aiming at reducing the power losses and processing time, analyze the power flow features, and build the potential path to forward partial input power to the output side directly to minimize the power processing times. 3) Compare existing practical soft-switching DC/DC topologies; develop the suitable magnetic coupling paths between the PFC stage and DC/DC stage to benefit each other, such as providing soft-switching condition for PFC stage or/and DC/DC stage. 4) Investigate integrated system issues and possible solutions, focusing on interaction between different stages and control schemes. 5) Set-up simulation platform and physical test bed, conduct comparative study for overall performance between the proposed topology and existing AC/DC converters.