# Multi-Objective Optimization of LCC-S-Compensated IPT System for Improving Misalignment Tolerance
## 4 Experimental Verification  
A 100 W prototype was built to verify the misalignment-tolerance capability of the proposed optimized compensation topologies. The photograph of the realized prototype is shown in Figure 10. The designed and measured circuit parameters are tabulated in Table 3. The primary inverter consists of four MOSFET IPW90R120C3, and four DSE12 \(\times\) 101-06 A units were used for the secondary rectifier. The planar circular coils without ferrites were used to achieve contactless energy transmission and their inductances \(L_{\text{P}}\) and \(L_{\text{S}}\) were 268.6 and 269.2 uH, respectively. The gap distance of two coils was 42 mm. The coupling coefficient dropped from 0.5 to 0.25 by moving the secondary coil different distances on the radial direction from 0 to 125 mm. Figure 8: Pareto solutions with different range loads for CVO-type IPT system. Figure 9: Main electrical values of CCO-type IPT system in case B: (**a**) output voltage; (**b**) input impedance angle; (**c**) current stresses on inductor and coils; (**d**) voltage stresses over capacitors. Implemented with Case A in the LCC-S compensation topology, the normalized output currents versus coupling coefficient are shown in Figure 11. The output current fluctuations of all three different load prototypes were quite small. Around a specific turning point at which the output trend reversed, the gradient of current gain variation was damped, thus significantly reducing the sensitivity of the output characteristic to coupling fluctuation. The outlines of these three curves are very similar to those in Figure 6a. The maximum output current was 1.12 A when the coupling coefficient was approximately 0.35 with the minimum load. The minimum output current was 0.94 A with the maximum load and coupling coefficient. When the value of \(R\) decreased, the fluctuation of the output current was smaller. With Case A parameters, the output current fluctuation was insensitive to both coupling coefficient and load, and the fluctuation was only 8.82% in the whole operating range. Some minor discrepancy can be mainly attributed to slight differences between the real parameters and designed ones. Figure 11: Normalized output currents and voltages of the LCC-S compensation topology designed by the new method. Figure 10: Prototype of the proposed LCC-S-compensated system. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type** & **Parameters** & **Designed** & **Measured** \\ \hline \multirow{4}{*}{CCO} & \(L_{\text{P1}}\) & 147.6 \(\mu\)H & 147.7 \(\mu\)H \\  & C\({}_{\text{P1}}\) & 41.87 nF & 41.97 nF \\  & C\({}_{\text{P2}}\) & 214.88 nF & 214.90 nF \\  & C\({}_{\text{S}}\) & 8.77 nF & 8.47 nF \\ \hline \multirow{4}{*}{CVO} & \(L_{\text{P1}}\) & 206.51 \(\mu\)H & 206.71 \(\mu\)H \\  & C\({}_{\text{P1}}\) & 33.64 nF & 33.66 nF \\ \cline{1-1}  & C\({}_{\text{P2}}\) & 692.13 nF & 698.33 nF \\ \cline{1-1}  & C\({}_{\text{S}}\) & 11.82 nF & 11.52 nF \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters of designed and experimental prototype. With Case C, the relationship between the normalized output voltage of the LCC-S compensation topology and the coupling coefficient is also depicted in Figure 11. The output voltage first rose and then decreased with respect to misalignment, which conformed to the theoretical analysis, indicating a strong misalignment tolerant capability, especially with the light load. Contrary to the CCO type, the output voltage did not increase as the resistance reduced. Due to the inevitable nonideal factors, such as equivalent resistance in power devices and voltage drop of diodes, the measured power transfer was lower than the designed value. However, the maximum voltage fluctuation with the proposed compensation network was less than 10.4% over the coupling range from 0.25 to 0.5. Figures 12 and 13 show the steady-state waveforms of two types of compensation topologies designed by the proposed method under maximum and minimum misalignment, respectively.