Is this circle worth developing, knowing that I am a beginner?
View attachment 146636
Hi,
You can make a boost converter with a higher ratio like 1:10 but you have to pay attention to detail and what has been done in the past. There are boost converters out there that do 1:10 but they are more carefully designed, and above all, HAVE FEEDBACK.
That's one major thing that your design is missing, feedback. You have to have some mechanism that can measure the output voltage and can provide a signal to the control part of the circuit that allows it to adjust the output voltage so that it stays constant. However, with that said, LED drivers are best when they can provide a constant current not a constant voltage. You may get by with a constant voltage though as long as you do not see the current change too much as the LEDs heat up.
So, the first thing wrong with the circuit is there is no feedback which is almost mandatory for this kind of circuit. If you do not use feedback, you have to put up with changes in input voltage and output impedance. It's not that that will never work, but you'd have to test it very carefully to make sure nothing changed too much.
The second thing is the MOSFET driver. A transistor and 220 Ohm resistor is not going to cut it. The MOSFET will most likely not turn off fast enough. A lot of the power in a MOSFET can end up being due to the switching times, the rise and fall times, when there is both current through the MOSFET and voltage across it. That means you should have fast switching times. This also plays in with the "total resistance" issue with boost converters which I'll get to in a minute. So the second thing you have to do is use a better MOSFET driver. There are all kinds on the web you can do a search. The simplest would be a two transistor setup which turns the MOSFET on with one transistor and turns it off with another transistor.
The third thing is the "total resistance" issue that plagues all boost converters. This is the combined resistance of all the power dissipating devices that appear in the circuit. This limits the input-to-output ratio and duty cycle.
For higher input-to-output ratios you need a low total internal resistance.
If you look at the attachment you'll see a blue plot and a red plot. The voltage gain ratio is shown on the left and the duty cycle across the bottom. You have to increase the duty cycle to get higher input-to-output ratio but if you go too far (see where the blue plot falls when it gets close to a duty cycle of 1) the output actually falls, and it falls fast. That means you no longer get a boost in voltage. At the top peak of the blue plot you can see the voltage ratio is close to 13, meaning it would be possible to get a ratio of 10. That's with a fairly low total internal resistance. The red plot on the other hand is with higher total internal resistance, and we can see the peak of that only gets up to about 9 before it falls fast. That means with that higher resistance a gain of 10 would not ever be possible no matter what the duty cycle is.
This is one of the main problems with boost circuits, they can only boost so much, and that is mainly governed by the total internal resistance of the circuit that dissipates power. This would be due to almost every power handling part in the system including the transistor, the inductor, and the filter capacitor. The output load also has some influence over this because it causes more current to flow through all the elements. This means attention to these components is paramount to getting a boost converter to work right. Of course the control circuit also has to be right. It cannot be allowed to go 'off the deep end' where the control circuit wants to keep increasing the duty cycle and does not know where to stop.
So there you have three main issues that have to be addressed.
Feedback, MOSFET driver, and Total internal resistance.
Most designers these days choose a boost converter controller chip to take care of most of the control.