The better and more effective idea is to "calculate" the inductor value with an experimental set up and through some practical trial and error process as explained in the following paragraphs. A simple IC based boost and buck converter designs are shown below which could be used for determining the best possible inductor value for a particular SMPS boost converter circuit. The rule of the thumb is to use the number of turns slightly higher than the supply voltage , therefore if the supply voltage is 12V, the number of turns could be around 15 turns.
The above set up shows a basic IC PWM circuit, which is equipped with separate potentiometers for enabling an adjustable frequency, and an adjustable PWM output at its pin 3. Pin 3 can be seen connected to a standard boost converter configuration using the TIP transistor the inductor L, the diode BA and a capacitor C. The transistor BC is introduced to limit the current across the TIP so that during the adjustment process when the pots are being tweaked the TIP is never allowed to cross the breakdown point, thus the BC safeguards the TIP from excessive current and makes the procedure safe and foolproof for the user.
The output voltage or the boost voltage is monitored across C for a maximum optimal response during the entire testing process. Your inductor parameters are now determined and could be used for any boost converter for the best optimal response. The current spec of the inductor could be increased by simply using many parallel wires while winding it, say for example you could use around 5 nos of 26SWG wires in parallel for empowering the inductor to handle 5amps of current.
The next diagram shows the process of optimizing and calculating inductors in SMPS, for a buck converter application. The same process applies for this set up too, as was done with the above explained boost converter design. As can be seen the output stage is now altered with a buck converter set up, the transistors are now replaced with PNP types and the positions of the inductor, diode changed appropriately.
Thus, by using the above two methods anybody can determine or calculate inductors in buck boost smps circuits without using complex and unfeasible formulas. If you have any circuit related query, you may interact through comments, I'll be most happy to help! Your email:. Thank u mr swagatam i understand the principle better it is a trial and error thing I will do and let u know sir. Thank u Alex.
Alex, ……it's not quite a trial and error method, because here you are able to monitor the results while optimizing it. I made a buck convertor that drive a high voltage dc to convert v dv to v dc. The pwm signal used 31 khz from ardino. But my out put is 28v only. Where is my mistake. Inspate of Gate voltage is nearly 10v. I hope you have understood the theory.
Sir What happend when the indectence value is smaller than specifaid indectence of buck convertor. Is it effect the out put voltage of bucknconvertor? The indectence value is directly or indirectly propotional to out put voltage of buck convertor.
Kiran, smaller than the required level will cause heating up of the coil and the driver transistor. The difference between the output power and the input power is the what we looking for heat dissipated 0,88W. If you can build a switching regulator correctly then you should go for that, and get maximum efficiency. You can refer to this LM based switching regulator also:. Hi, it is possible to reduce the voltage to 5V, you must check by connecting a dummy load of may be a 1K resistor at the output.
You will have to also experiment with the frequency for lowering the voltage and make sure the frequency matches with the coil inductance. Please I need a simple dc-dc converter circuit to step down 48v to 12v for my inverter oscillator stage.
I tried this ic buck converter circuit but the the Vout just had 0. Create Alert Alert. Share This Paper. Background Citations. Methods Citations. Figures and Topics from this paper. Citation Type. Has PDF. Publication Type. More Filters. View 1 excerpt, cites background. An inverting buck-boost converter provides an output voltage that may be less than or greater than … Expand. View 1 excerpt. View 2 excerpts, cites background.
Design and simulation of PI-type control for the Buck Boost converter.
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