A Totem-pole PFC with Re-rush Current Control, Accurate E-metering, Low iTHD and High Power Density

This paper proposed novel control algorithms and design approaches for a high-performance power factor correction (PFC) design: A relay and PFC control algorithm is proposed to handle the re-rush current when AC comes back from a dropout event. An e-meter function is integrated with PFC control using a single current sensor and a single microcontroller (MCU) for both e-metering and PFC control, eliminating the traditional dedicated metering device, and achieving 0.3% accuracy. An AC cycle skipping algorithm along with PWM soft start scheme after AC zero-crossing, and a method to eliminate the voltage loop double line frequency ripple are introduced to reduce total harmonic distortion (iTHD) and meet the strict iTHD specification in the recently released Modular Hardware System – Common Redundant Power Supply (M-CRPS) specification. A baby boost converter is added between PFC and the following isolated DC/DC converter stages to reduce bulk capacitor capacitance, increase power density and maintain hold up time. These algorithms are implemented in a 3kW totem-pole bridgeless PFC design, test results show it meets the M-CRPS specification.