Analytical Framework of S-Parameter-Based Efficiency for Secondary-Parallel Compensation WPT System to Authenticate Data Using VNA

Resonant wireless power transfer (R-WPT) is the most efficient system in near-field applications. Predominantly, four distinct resonant topologies exist for R-WPT to enhance the power transfer efficiency (PTE) under different load conditions. Here, the PTE is considered crucial for gauging the R-WPT system performance. In a typical experimental scenario, measurement of the PTE is performed by exciting the transmitter (Tx) coil with a sinusoidal signal using a high-frequency inverter source. Therefore, the input and output power measurements are conducted using an oscilloscope. Here, the measurement using an oscilloscope is highly susceptible to external noise. As an alternative, the vector network analyzer (VNA) is the most accurate instrument to measure
$S$
-parameters with high precision, even at very high frequencies. The
$S$
-parameter-based analytical expressions for evaluating PTE are available only for series–series compensation topology. Therefore, VNA usage is severely limited for experimental validation of the other compensation topologies. This article proposes an analytical evaluation of
$S$
-parameter-based PTE for secondary-parallel compensation topology as a contribution. Moreover, the mathematical proof is deduced to determine the active operating load condition for the secondary-parallel capacitor. Error analysis of experimental data is performed where the signal-to-noise ratio (SNR) of the measurement system is greater than 35 dB and the percentage error rate
$\epsilon $
is less than 1.3%, which implies high precision and accuracy of the
$S$
-parameter-based VNA measurement system.