Say Goodbye to the "Electricity Gag": 99.2% SiC Bidirectional PFC, Reshaping the Energy Future

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Traditional power supply solutions based on silicon devices and bridge rectification are like an untamed "electric tiger"—converting precious electrical energy into heat and wasting it away in every energy conversion. However, the mature mass production of third-generation semiconductor SiC (silicon carbide) has equipped high-power systems with a truly "green heart."

Against this backdrop, Avnet has developed a 3.3 kW high power density bidirectional PFC solution based on Infineon CoolSiC™ , with a maximum efficiency of 99.2% and a power density of approximately 72 W/in³, designed specifically for next-generation high-energy-efficiency applications.

At the heart of this solution is a bridgeless totem-pole power factor corrector (PFC) topology.

Totem-pole PFC is an ideal topology for achieving high efficiency and high power density. Unlike traditional boost PFC, the totem-pole architecture eliminates the rectifier bridge, directly using the high and low bridge arm switches to complete rectification and boosting. Eliminating the voltage drop across the entire series of diodes in the rectifier bridge frees up valuable efficiency headroom, which is the primary prerequisite for the system to reach a peak efficiency of 99.22%.

Totem-pole PFC achieves efficiency exceeding 99%. In addition to topology optimization, the selection of switching devices is also crucial, with SiC currently being the mainstream high-performance choice.

This solution employs Infineon CoolSiC™ MOSFETs for the high-speed bridge arm and CoolMOS™ superjunction power MOSFETs for the low-speed bridge arm, achieving synchronous rectification and loss optimization. At high frequencies, it effectively reduces conduction losses and reverse recovery losses, thereby better translating "structural advantages" into "system efficiency."

Achieving an efficiency exceeding 99% relies not only on power devices, but also on system intelligence.

Excellent power stages alone are not enough; a sufficiently intelligent brain is also needed. The system's control core utilizes the Infineon XMC™ 1404 (Cortex-M0 core) to achieve fully digital closed-loop control and mode management. In terms of control strategy, it employs a CCM continuous conduction mode + duty cycle feedforward (DFF) algorithm, maintaining good dynamic response and low ripple performance even at switching frequencies above 65 kHz.

In the face of high-voltage, high-power, and high dv/dt operating environments, reliability is the bottom line for power supply engineering. To this end, this solution constructs a complete safety closed-loop mechanism from the input end to the control end, consisting of a three-level protection architecture: "surge protection → power-on current limiting → MCU intelligent overvoltage/overcurrent protection" .

The system is also equipped with an auxiliary power board that uses the quasi-resonant flyback circuit of Infineon's second-generation controller ICE5QSAG, eliminating the need for a Snubber absorption circuit and improving efficiency.

Actual test results show that when the power exceeds 200W, the PFC efficiency is above 97% under three voltage input conditions: 200V, 220V, and 245V. Furthermore, it achieves a peak efficiency of 99.22% under 245V AC conditions , reaching industry-leading energy efficiency performance.

This high-efficiency system relies not only on active components, but also on the quality of passive components, which determines energy efficiency and long-term reliability. Therefore, high-performance components from Panasonic and TDK were selected in the surge protection design to ensure low losses, low temperature rise, and longer lifespan.

With its ultra-high efficiency, bidirectional capabilities, and compact design, this solution has become a "core driver" in many high-growth sectors: telecommunications, server power supplies, solar inverters, energy storage, industrial power supplies, charging stations, battery formation, chargers/electric vehicle chargers, electric transportation, and most other scenarios that require "turning electricity into more valuable electricity."

When energy efficiency surpasses the 99% threshold, it's not just a series of numbers on a datasheet that changes, but the mindset of the entire industry chain. In the future, we believe that power supplies will no longer be "passive energy modules," but rather proactive players in energy dispatching, power interaction, and system intelligence. It's time to say goodbye to the "old era" of high losses and bulky designs. Embracing SiC is embracing a cleaner, smarter, and more resilient energy future.