Why the boost converter cannot increase the voltage with a resistor load?

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abusurd

Joined Feb 1, 2024
1
I have an assignment where I have to make a boost converter. this is the schematic of the circuit I have;

enter image description here

the problem is that the boost converter can increase the voltage if the load used is a 2.5 watt incandescent lamp (can go up to 12 V), while if I use a resistor (100, 220, 470 ohms etc.) the voltage drops to 1-3 volts. How to solve it?

components that I use;

  1. IRFZ44N Mosfet
  2. Diode 1N4007
  3. ballast inductor (1.42 H)
  4. Capacitor 470 uF
with an input of 5 volts, frequency 490 Hz, and duty cycle range from 0.2 to 0.8

+ one more questions, can I make buck, boost, and buck-boost converter with the same components?
 

Papabravo

Joined Feb 24, 2006
21,225
So what is going on is that a hot filament has a higher resistance than a cold one. Once the bulb turns on the required current goes down and the voltage of the converter can be maintained. The resistors have a fixed value, and it requires an amount of power that cannot be supplied.

Operation of a boost converter is governed by the immutable law of DC-DC conversion schemes. It is the following:

The power out will ALWAYS be less than the power in. Sometimes it will be much less.

I did not run the numbers, but it does not look very efficient. Also, your switching frequency is way too low at 490 Hz. and your inductor is way too big at 1.47 H. Using a 1N4007 diode instead of a Schottky diode is also a bit sus. Did you actually design this, or did you find it in a magazine?
 
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