MOSFET & Transformer Selection for power inverters d.c to a.c

Hi, I'm designing on Non Contact Charging System for Smartphone, Where I have designed the draft diagram of the circuit. I'm using power inverter with transformer to convert from 24 Vd.c to a.c and finally a rectifier to convert from a.c to 5V d.c from transformer with a supplying current of 500mA.

However in the power inverter there are four switches used, whereas in my case I choose to use N Channel Mosfet switch for power inverter.

I have a problem with choosing the correct N-Channel MOSFET for the inverter and transformer (inductor).

Show us your circuit diagram.

Hi, As I have discussed with with my tutor, he told it would be easier to use a Op Amp Sine wave generator instead of power inverter. He told to use a Op -Amp Sine wave generator to turn 24 +/- 8 V D.c set into A.C signal and after using the Op-Amp, I found that a Amplifier is used and transformer (step down) and voltage regulator. I have no idea how to choose the exact circuit for Op- Amp and Amplifier circuits.