What counterintuitive logic is it that the efficiency of the 11KW AC charging pile motherboard using SiC/GaN solution is actually higher than that of the traditional 7KW motherboard?

SiC/GaN enables the efficiency of 11kW charging piles to surpass that of the traditional 7kW scheme, with the core being the exponential reduction of switch losses and the dispersion of three-phase currents, breaking the intuition that "the greater the power, the hotter it is".

The loss dilemma of traditional silicon-based materials

• 7kW silicon-based IGBT/MOS for pile, switching frequency 20-50kHz, efficiency 93-95%.

• Losses are divided into conduction losses (current ² x resistance, accounting for 60%) and switching losses (voltage x current x time x frequency, accounting for 40%).

• The 7kW output generates 350-500W of heat and requires forced air cooling.

Physical Generation Difference of SiC/GaN

• The bandgap width of SiC/GaN is three times that of silicon, and the electron drift speed is 2-3 times faster.

• Direct result: When the switching speed is reduced from 50-100ns to 5-20ns, the switching loss decreases by 80-90%; Under the same withstand voltage, the on resistance Rdson decreases to 1/5-1/10; The body diode has almost zero reverse recovery, eliminating trailing losses.

11kW efficiency exceeds the account

The 11kW pile uses SiC three-phase PFC+LLC, with a switching frequency of 100-200kHz:

• Conduction loss: Three phase 16A dispersed in three channels, each current is halved compared to 7kW single-phase 32A, and the total I ² R loss is lower

• Switching loss: The single loss is reduced to 1/10, and even after doubling the frequency, the total switching loss still decreases by 50-70%

• Comprehensive efficiency: SiC 11kW measured 97-98%, traditional silicon-based 7kW only 93-95%

• Heat comparison: 11kW × 2%=220W, 7kW × 5%=350W. High power actually generates less heat.

Chain income

• Natural heat dissipation is sufficient for 220W heating, while forced air cooling is required for 350W heating.

• SiC 11kW piles can be made into fanless seals (IP67), eliminating the need for fans, heat sinks, and dust nets, and reducing system costs.

• The volume of magnetic components is reduced by 30-50%, saving copper and iron usage.

Cost Paradox

• SiC devices are 3-5 times more expensive, but eliminating heat dissipation saves 100 yuan, eliminating fans saves 50 yuan, reducing magnetic components saves materials, and maintenance free saves operation and maintenance.

• Integrated BOM: SiC 11kW is 200-400 yuan more expensive than traditional 11kW, but only 100-200 yuan more expensive than traditional 7kW, while efficiency has increased from 93% to 98%.

Conclusion:

SiC/GaN blocks the "efficiency black hole" of switch losses, and the three-phase dispersed current suppresses conduction losses, achieving "high power, high efficiency, low heat generation, and fanless". In the future, 7kW silicon foundation piles will be hit by 11kW SiC piles for dimensionality reduction, and 7kW will have to replace SiC to survive.

The communication charging pile motherboard produced by Xincheng Technology is of high quality and beautiful price. Welcome to inquire and purchase!