Talk:Boost converter

The present circuit analysis is one that I have not seen before. It seems to be a nice simplification. However, in its present form it is not easy to follow. I'd like to be able to divide the Circuit analysis section into three different areas: the present simpliied analysis, a more clasical analysis, and a presentation of the discontinuous operation. Also, some insight into the effects of parasitic elements (switch resistance, diode switching time, etc) would be helpful. Mak17f 00:18, 12 December 2005 (UTC)

I feel that the article should center on the concepts specific to boost converters. Discussion on items such as switching elements, discontinuous mode, and parasitics deviate from this concept. The items listed relate to dc-dc supplies in general and are best placed in either SMPS or dc-dc converters topics or should become topics on their own.GrantPitel 02:18, 13 December 2005 (UTC)

The circuit diagram is somewhat confusing, since it only has a single switch while the rest of the article talks about two switches.
 * In the power electronics realm, "switch" is used to mean the semiconductor devices (diodes, BJTs, SCRs, etc). In the diagram, the diode is a switch. I'll update the article to clarify. Mak17f 17:10, 10 March 2006 (UTC)

Parasitic Resistance
I've been staring at this article for a while now and can't understand the parasitic resistance calculations. If Rl is your DC inductor resistance then what is R. I'm trying to calculate Vo/Vin ratio. Any help would be much appreciated.


 * You're right, R is not defined in the article. It is the resistance of the load. I edited the article to introduce it. Is it clearer? CyrilB 09:33, 7 July 2006 (UTC)

++ Equation not rendering properly ++ An equation on about page five is not rendering. It displays:

I_o=\frac{V_i\cdot D\cdot T}{2L}\frac{V_i\cdot D}{V_o-V_i}=\frac{V_i^2\cdot D^2\cdot T}{2L\left(V_o-V_i\right)}


 * Is that the equation in section "Discontinuous mode", after "Replacing ILmax and δ by their respective expressions yields:" ? On my machine, it looks alright.CyrilB 20:56, 4 February 2007 (UTC)

Additional figures/simulations
I teach an introductory circuits lab, and I recently got a question about switchers, so I added some simulations to the course web site. If anyone here finds them useful, they can use them.

See Lab 3 of my ECE327 course web page:

http://www.ece.osu.edu/~pavlict/ece327/#lab_voltreg

There are three MATLAB sims (LC resonator, LC resonator with catch diode, and boost switcher) each with some sample results. The sims use ode45 to generate the results. --TedPavlic | talk 15:21, 17 April 2008 (UTC)

Continuous/Discontinuos mode boundary
There was a nice picture which depicted CCM/DCM boundary along with the text that depicted it, why was it edited out ?

--VEC7OR 84.15.124.117 (talk) 23:53, 24 July 2008 (UTC)

RF emission characteristics?
What is the RF spectrum emitted by the inductor? Is it a function of the other parameters of the circuit, or stochastic? Since there is a switch, the frequency domain seems to have the noise and associated harmonics characteristic of discontinuous functions with their large impulse. That would imply that the emission is a Gaussian distribution in the frequency domain; if so, or even if that is merely a useful approximation, what determines the mean and variance? Pannag Salmon (talk) 18:29, 14 October 2008 (UTC)


 * In continuous mode, the current through the inductor is somewhere between a triangle wave and a sawtooth wave.
 * The RF emitted by the inductor comes from the magnetic field, which is directly proportional to that current.
 * The simplest case is a converter that uses a switching regulator that forces a constant switching frequency (only changing the duty cycle). Then the RF spectrum is a bunch of spikes at that switching frequency and its harmonics -- see triangle wave and a sawtooth wave for the Fourier spectrum.
 * I suspect that the spectrum in discontinuous mode is pretty similar.
 * Some switching regulators do not force a constant frequency, but instead run at a higher frequency when the load pulls more power. That will shift the position of the spikes -- and if the load changes continuously, blur those spikes into some sort of continuous distribution -- perhaps a Rayleigh distribution ?
 * I suppose I should also point out that in a properly-designed converter, using a shielded inductor, a Toroidal inductors and transformers, or external shielding -- or some combination -- there is no significant RF spectrum emitted. --68.0.124.33 (talk) 22:36, 6 December 2008 (UTC)

function of inductor is largedly simplified in the article. note that there is no 'collapse of magnetic field' - see topic related : https://en.wikipedia.org/wiki/Relativistic_electromagnetism there is actually no 'magnetic field' at all in the nature.

To properly design inductor - so it does not work as antenna - one needs to take it's geometry into consideration. Also there is no such thing as ideal inductor in nature - for calculations one needs to create RLC model equivalent. Rule of thumb is that one needs to keep the inductor much smaller than the minimum switching frequency wavelenght (1/20 of wavelenght approx). This is usually easily achieved by using inductors wound on small ferrite cores. 83.15.83.107 (talk) 23:47, 3 February 2016 (UTC)

Queries regarding Boost converter.
we had constructed a converter of 48v to 440v (40A) by using switch and a duty cycle of 20K Hz. while the switching occurs a disturbances are injected to source. The disturbances are low when i used small length wire (0.5 Meter) and the disturbance was more when i used length wire (2meter).

we had high frequency 1 micro farad capacitor across switch and three capacitor across load.Inductor value was 600 micro Henry and can withstand up to 40A.

i need help for reducing maximum disturbances which are injected to source.Because source was a battery and the life of it was effected due to disturbances.

please mail your suggestions to my email Id: arun.k@tribitech.com —Preceding unsigned comment added by 122.172.85.133 (talk) 05:50, 16 January 2009 (UTC)

Input Current
"The input current is discontinuous, stepping between a very high inductor current and 0."

This statement is misleading. The input current is the same as the inductor current, so it rises above the load current when the switch is closed and falls, possibly to zero, when it is open. There are no step changes. --Nophead (talk) 10:32, 29 April 2009 (UTC)

Opening paragraph inaccuracy?
A joule thief boost converter has only a transistor and no diode, in simple form. The first paragraph my seem to imply that a boost converter with only one capacitor and no inductor is possible, which I doubt. David R. Ingham (talk) 22:43, 3 November 2014 (UTC)

I think you will find that the LED is the diode in a Joule thief. 204.174.36.149 (talk) 15:09, 23 December 2019 (UTC)