Hi Jojo,
Can you kindly pm me how much it would cost to have a prototype for this?
for those who want to DYI even the frequency converter, here's a circuit for your reference:
PCB Inverter 100W by IC 4047 + 2N3055
This circuit Inverter input 12V (battery 12V)
to out 220V 50HZ, Eesy circuit because less component to use.
It use IC 4047 (oscillator 50HZ) and
Power Transistor 2N3055 x 2 ,OUTPUT Power 100W.
Thanks,
JackRyan