Wireless Power Transfer: Breaking the 90% Efficiency Barrier

Introduction

The wireless charging market will reach $27 billion by 2027 (Allied Market Research), yet efficiency losses remain the Achilles’ heel:

• Typical systems waste 15-25% as heat
• 3-5% efficiency drop per mm of misalignment
• Thermal constraints limit power scaling

Briltech’s power electronics lab reveals how new coil architectures and control algorithms are solving these challenges.

Section 1: Coil Design Breakthroughs

1.1 3D Printed Magnetic Structures

Case Study: Our hexagonal array design achieved 92.3% efficiency at 65W (Qi 1.3 spec) with <5°C temperature rise.

1.2 Active Alignment Compensation

• Hall sensor arrays detect receiver position (±0.25mm accuracy)
• Dynamic coil segmentation maintains >85% efficiency across 15mm x/y movement

Section 2: Semiconductor Innovations

2.1 GaN vs. Si MOSFET Performance

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65W Wireless Charger Comparison:  
Parameter       Si MOSFET   GaN HEMT   Improvement  
Switching Loss  1.2W       0.45W      62.5%  
Rise Time       28ns       9ns        67.8%  
System Eff.     88%        91.5%      3.5pts  

2.2 Adaptive Frequency Control

Algorithm Logic:

if (k < 0.7) {  
  freq += 5kHz; // Increase resonance  
} else if (temp > 60°C) {  
  freq -= 10kHz; // Reduce eddy currents  
}  

Section 3: Regulatory Compliance

3.1 EMI Reduction Techniques

• Spread-spectrum clocking (FCC Part 15 compliant)
• Shielded Litz wire reduces radiated emissions by 12dB

3.2 Safety Protocols

• Foreign object detection (FOD) sensitivity:
  • Metal: 0.5g detection threshold
  • Living tissue: 0.1°C temperature monitoring