Wireless Power Transfer Toolbox
Air Core Coil Design
Useful Calculator
Coil design
Coil type
Planar Coil
Helix Coil
PCB Coil
Turns N
Planar start radius Rstart (mm) (innermost center radius)
Pitch (mm) (centerline spacing per turn)
Wire diameter dwire (mm)
Environment εr (air≈1)
Planar layers
Layer spacing (mm) (center-to-center)
Layers are stacked by copying layer 1 to upper layers with the same winding direction.
Copper thickness t (mm) (1oz≈0.035)
Trace width w (mm)
Start radius Rstart (mm) (center radius of innermost turn)
Pitch (mm) (= width + spacing)
Spacing = pitch − width (must be ≥ 0)
Substrate material
FR4 (εr≈4.2)
Polyimide (εr≈3.4)
Substrate εr
Compute
Computed Din (mm)
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Computed overall D (mm)
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Inductance L (H)
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Parasitic Cp (F) (rough)
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Self-resonant fSRF (Hz)
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Tip: drag to rotate the solid 3D preview.
Tools
1) Pulse timing from frequency
Frequency (Hz)
Duty (%)
Calculate
Apply to Simulation (T & ton)
Period T (s)
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ton (s)
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toff (s)
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2) Resonant calculator
Inductance L (H)
Frequency (Hz)
Apply C to
C1
C2
Calculate
Apply to Simulation (C1/C2)
C (F)
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Formula: C = 1 / ((2πf)² · L)
3) Resonant inductor from capacitor
Capacitance C (F)
Frequency (Hz)
Calculate L
L (H)
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Formula: L = 1 / ((2πf)² · C)