The impedance of the charger (power bank) and the charging battery should be very low and the inter connecting cable length should be very minimum . The total of all the three should have less IR drop. if you design like this the efficiency will be very good.

Use lots of copper, a low distance and big area - that always helps.

By the following

- Make the air-gap as small as possible

- Achieving ZVS

- Increase the coupling area between the coils

- Ensure well-alignment

Read more about WPT in my researchgate page, I have so many works about this

1-You can start with Series-Series compensation which has a very easy tuning formula:

C1=1/(Lp*(2*3.14*f)^2)

C2=1/(Ls*(2*3.14*f)^2)

Lp and Ls are the primary and secondary self-inductance of the magnetic couplers.

2-Consider a lossless model for all the components.

3-Use a resistor as a load instead of the diode bridge on the load side.

4-Instead of inverter you can use an AC voltage source.

Relationship between coefficient coupling, mutual inductance and distance between the two coils

Concerning the compensation network, you should first analyse if the charger is going to be always used with a predefined gap or it can have misalignments. You have to analize the power rates in the componets too. The most simple solution is the Series-Series.

I have made a comparative study between various compensation topologies, as you can see on my page. See what characteristics you would like to get and then choose the compensation topology accordingly.

Conference Paper Analysis and Comparison of Resonance Topologies in 6.6kW Ind...

Sir I want small basic MATLAB model in wireless power transfer in ev charging, please help, now I am started my work