Design of integrated circuits for switching power supply with power factor correction

Abstract

This is a Teaching Company Scheme between The Hong Kong Polytechnic University and ON Semiconductor Ltd. In this project two new circuits of AC-DC regulators with power factor correction have been proposed and thoroughly studied. Hardware prototypes of both circuits have been constructed, evaluated and compared with ordinary circuits. The first circuit, "A novel ZVS switching mode power supply with Power Factor Correction", employs a special converter topology and a unique gate drive sequence (for MOS switches) to achieve both power factor correction and soft switching. The new circuit is capable of regulating the output for a wide range of loading current and has a fast transient response. A patent application on this design has been filed. The second circuit, "A Pulse Skip Modulation PFC controller", uses a pulse skip method to control the average input current and to reduce the voltage stress of both active and passive components (e.g., electrolytic capacitors and switching transistors). In this way a high power factor, a better reliability and a lower cost can be obtained simultaneously. The power factor correction function is well maintained over a wide range of loading current. Both of the two new circuits operate at fixed switching frequency. This makes the design of EMI filters much easier, when compared with a variable-frequency converter. As an important objective of this Teaching Company Scheme, the controllers for the above-mentioned new circuits are to be integrated into IC form. Therefore the controller and driver circuits have been designed in such a way that they can be readily fabricated as ICs using existing technologies.