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WPT compensation network calculator

Enter the coils, coupling, frequency and the DC voltages on each side; the compensation component values and the operating point appear as you type. Ideal square-wave inverter, ideal rectifier, first-harmonic analysis.

Topology
Inputs
Compensation components
Cstx
Tx series capacitor
35.06 nF
nF
Csrx
Rx series capacitor
35.06 nF
nF

Type a value to override it and see the operating point move — the drive voltage and the load stay fixed, so detuning shows up as a change in delivered power.

Operating point
QuantityCalculated
Vin_acinverter fundamental, RMS90.032 V
Mmutual inductance25.00 µH
ItxTx coil current, RMS3.237 A
IrxRx coil current, RMS6.743 A
IoutDC output current6.071 A
VoutDC output voltage48.000 V
Poutdelivered power291.402 W
R_loadDC load, Vout²/Pout7.907 Ω
R_acAC-equivalent load, 8·R_load/π²6.409 Ω
ηideal — lossless by assumption100.0000 %

inverse solve: linear · 1 iterations · residual 1.4e-16

Circuit
INVVinCstx35.1 nFCsrx35.1 nFRECTVoutk · MLtxLrx
Notes
  • Ideal assumptions: zero coil/compensation ESR, zero rectifier diode drop, first-harmonic (FHA) analysis. Efficiency is therefore 100 % by construction — it is a consistency check on the assumptions, not a prediction.
Continue as a full design

Opens a design session pre-filled with these constraints — coil losses, part selection, stress and simulation. Requires sign-in.

How this is calculated

Assumptions

  • Ideal full-bridge inverter: a square wave whose fundamental RMS is Vin_ac = (2√2/π)·Vin_dc.
  • Ideal rectifier with a capacitive output: zero diode drop, AC-equivalent load R_ac = 8·R_load/π².
  • Zero ESR on the coils and the compensation elements — efficiency is therefore 100 % by construction.
  • First-harmonic approximation (FHA): only the fundamental is carried through the tank.

Formulas

ω = 2πf₀
M = k·√(Ltx·Lrx)
Vin_ac = (2√2/π)·Vin_dc
R_load = Vout²/Pout  ·  R_ac = 8·R_load/π²
Cstx = 1/(ω²·Ltx)  ·  Csrx = 1/(ω²·Lrx)
Irx = Vin_ac/(ω·M)
Pout = 2√2·Vin_ac·Vout/(π·ω·M) = 8·Vout·Vin_dc/(π²·ω·M)

How the power is found

The underlying engine is built the other way round: you give it a power and it returns the bus voltage that power needs. This page inverts that numerically — it searches for the power at which the required bus voltage equals the Vin you entered, refining with a bracketed secant method to a relative residual below 1e-10. Every component value, current and efficiency shown above comes straight from the engine at the converged point, so there is exactly one source of truth.

Note that SS behaves as a gyrator (output current is set by Vin, so power falls as coupling rises), while LCC-S fixes the voltage ratio instead — for LCC-S the power is an independent input, not something Vin and Vout determine.