How Can Current Output Be Increased in a PWM-Based Boost Converter?

[Hina Gohar]

I am designing DC-DC capacitive based charge controller for charging 12V battery using variable dc power supply and then with solar panel as input sources.This charge controller topology is step up boost converter so by using PWM variable duty cycle technique I made its output fixed at 12V but problem is that this circuit produces very minimum current from 100 to 500mA..so maximum output power is P=12*500m=>7W while I need around 40 to 50W power from this circuit as maximum power coming from solar panel is 40W.There must be power matching between source and load means as from panel 40W coming so this circuit must produce 40W.So how I can enhance current in this circuit kindly help.Circuit diagram of capacitor based DC-DC converter is attached plus block diagram of whole project.

 

[Simon Bridge]

Where in the circuit are you measuring the current and the voltage?
Where does the 12V battery go in this circuit?
Where does the microcontroller get it's power from?

Generally you cannot just set the voltage and current for a load at the same time - you fix one and the load determines the other.