Convert 3v to 5v very high amperage using boost converter
Convert 3v to 5v very high amperage using boost converter


If the input voltage is 3 volts and the inductor is 3 mH and the switching cycle is 15.625 us (inverse of 64 kHz) then the maximum switched current into the inductor at near enough 100% duty cycle is 3 volts x 15.625 us / 3 mH = 15.625 mA. 

This clearly and obviously is the DCM (discontinuous conduction mode) case but, it is so far off meeting the requirements that it's obvious that the CCM (continuous conduction mode) case is impractical.

You have a value of inductance that is way too high. You need an inductance that is single digit micro henries.



Edited section to show the futility of a 3 mH inductor

If you did a simulation of the only possible technique to achieve 5 volts from 3 volts with a 3 mH inductor at 64 kHz switching (continuous conduction mode), you would find that the inductor current rating needs to be at least 6 amps: -



The top picture is the simulation circuit. The middle picture is the transient response showing output voltage (blue) and inductor current (red).

The bottom picture is focused in on the inductor current showing that it changes between 5.652 amps and 5.662 amps. This delivers a net power to the diode, capacitor and load of about 10.82 watts.

Now, if you tried to find a 3 mH, 6 amp inductor, you would be surprised how big and costly it would be. The largest current 3 mH inductor in Farnell was rated at 500 mA and have a DC resistance of about 3 ohms. The inductor you would need for this design requires at least 12 times the current and would cost several tens of dollars.

Of course you could wind your own BUT, the point is that you have chosen the wrong value inductor for this application. Choose something around 10 uH.