Wireless Charger Coil

About Wireless Charger Coil

Wireless charger coils (Tx/Rx) transfer power via electromagnetic induction based on standards Core specifications include inductance (typical range: 6.3 H to 12 H), operating frequency (100--205 kHz), and dimensions tailored to the device's power requirements (e.g., 30 mm for wearables, 40--50 mm for smartphones)

• Inductance (L): Typically measures between 6.3 H to 24 H for standard transmitter/receiver, determining the resonant frequency.
• DC Resistance (DCR): Lower resistance (e.g., 0.05 to 0.2 ) reduces power loss and heat.
• Quality Factor (Q): Measures the efficiency of the coil; a higher Q-factor indicates less energy loss and better coupling.
• Operating Frequency: Usually resonates between 100 kHz and 205 kHz for standard Qi wireless power transfer. 
• 2. Form Factor & Physical Size
  • Coil Outer Diameter:
    • Wearables/Earbuds: 30 mm
    • Smartphones (Standard & Fast): 40 mm to 50 mm
    • Laptops/Multi-device: 50 mm to 60 mm+ 
  • Thickness: Ultra-thin coils for portable batteries and phones range from 0.5 mm to 2.3 mm
  • 3. Material Composition
    • Winding Material: Litz wire is preferred for minimizing skin effect losses at high frequencies, though printed circuit board (PCB) coils are used for miniature designs. [1, 2, 3, 4, 5]
    • Magnetic Shielding: Ferrite plates or sheets (WPC compliant) act as a magnetic shield to direct the flux and prevent the electromagnetic field from heating up metal housing or the battery.