## 5 Conclusions and Discussions
The ZVS performance of TPS control is conducted in the circuit simulation in the simulated CC mode control and CV mode control of battery charging condition by replacing the load resistor with a DC voltage supply to emulate the battery. The simulation results show that Sic MOSFET switches of the inverter and rectifier work at ZVS soft-switching conditions in the emulated CC mode charging with a low battery equivalent load resistance. However, in the CV mode charging with large battery equivalent load resistance, one of the inverter/rectifier Legs may lose ZVS soft switching. This explains why the measured efficiency is still around 20% lower at a smaller power condition with larger DC load resistance connected, even if the R\({}_{\text{ac}}\) control is enabled. From the circuit simulation results, a slight adjustment of inverter-to-rectifier angle may not improve the ZVS switching in CV mode operation. The proposed TPS control is validated in a small power laboratory experimental setup. The achievable efficiency is from 60% to 80% for the output power range from 1 W to 35 W. The efficiency improvement with R\({}_{\text{ac}}\) feedback control enabled is around 30% at power level from 1 W to 5 W. The total efficiency measurement from this small power wireless charging DAB LCC resonant converter experimental setup is lower than the published efficiency from a large power wireless charging setup. This is because, at a low power level of around 30 W, the small SIC MOSFET switching and conduction loss contribute to a significant percentage of power efficiency reduction. Efficiency improvement from 30% to 60% at 1 W to 5 W power level with R\({}_{\text{ac}}\) feedback control enabled indicates that winding loss is a significant contribution for the wireless charging system even at a very low power level. For kW range, high power EV charging application, the efficiency of the proposed TSP control scheme will be much better than the DAB control solutions published as a result of optimized R\({}_{\text{ac}}\) feedback control and the unity power factor operation of DAB converter bridges resulting from a significant reduction in winding loss in the wireless charging system. There are some engineering challenges to implementing the proposed TPS closed-loop control scheme in the wireless charging system with separate transmitter and receiver control hardware. The paper provides some basic ideas on how to implement the inverter and rectifier PWM modulation separately. The power-on startup transition stages are required to be added smoothly to enable rectifier side phase shift PWM modulation in diode rectifier operation conditions. The inverter-to-rectifier phase shift angle is to be automatically adjusted to minimize the power factor angle to achieve the unity power factor operation. The feasibility study is done with circuit simulation. However, it requires considerate engineering effort to make the idea work in a suitable wireless charging product. Conceptualization, S.C., Y.C., R.T.N. and S.L. ; methodology, S.C. and Y.C. ; software, S.C. and Y.C. ; validation, S.C. and Y.C. ; formal analysis, S.C. and Y.C. ; investigation, R.T.N. and S.L. ; writing--original draft preparation, S.C. and Y.C. ; writing--review and editing, S.C., R.T.N. and S.L. ; supervision, R.T.N. and S.L. All authors have read and agreed to the published version of the manuscript. This research received no external funding.