Three-Channel Interleaved Totem Pole PFC in Triangular Current Mode (TCM) with STM32G474 Microcontroller

Abstract:
In PFC for Servers and Telecom (e.g., PSU for 5G stations) the achievement of an efficiency >99% is becoming often requested. For this reason, bridgeless topologies and resonant techniques are applied to reduce the power losses as minimum as possible. In this paper a three-channel interleaved totem pole PFC driven in zero voltage switching (ZVS) is presented. The ZVS condition is obtained applying the Triangular Current Mode (TCM) operation. This combination of bridgeless topology, resonant technique and interleaved architecture allows to reach the efficiency target >99%, also using standard Silicon MOSFETs. Generally, for these complex systems digital solutions are adopted, furthermore powerful DSP with FPGA are often used due to the required high computational effort. In this paper, the TCM technique combined with hysteresis current control strategy is modeled and fully implemented on a standard STM32G474 Microcontroller. A 2-kW prototype design, using standard Super Junction MOSFETs, is presented and the experimental results show an efficiency close to 99.2% at full load.