DC-DC Buck Converter theory - Page 1
Forum section: electronics / beginners

author: cyberlink
author_rank: Newbie
timestamp: April 13, 2016, 09:01:27 pm
content: Hi to everyone! Im new to the board but not new to electronics, though I am still (and always) learning.I am trying to wrap my head around the calculations to build a DC-DC buck converter. I have read several pages on it but they tend to go into long complicated explanations with formulas for calculating loss etc. I am really more interested in how you determine the inductance ,capacitor, and diode sizes to get the effective step down needed.I would be grateful is someone could point me to a simple explanation or maybe go over it here. I have done lots of linear power supplies but this is the first time I have looked at a dc-dc converter. My first thought was to oscillate the DC output, dump it into a step down transformer, then rectify it back out to DC but that seems like a lot of work to step down DC voltage. lolAlso curious if there are limits to the voltage a buck converter can be designed for? What I am looking at doing is stepping down millions of volts to the kilovolt range, so high voltage with extremely low amperage.Again, thoughts, pointers, and material to read would be greatly appreciated.Thank you

author: danadak
author_rank: Super Contributor
timestamp: April 13, 2016, 10:47:55 pm
content: No shortage of info on webhttps://www.google.com/search?q=buck+converter+video+design&oq=buck+converter+video+design&aqs=chrome..69i57.14600j0j7&sourceid=chrome&ie=UTF-8You say millions of Volts, clearly this will not be done with semiconductors. Can you explain better the designtask ?Regards, Dana.

author: cyberlink
author_rank: Newbie
timestamp: April 13, 2016, 11:34:08 pm
content: Quote from: danadak on April 13, 2016, 10:47:55 pmSure, when you coat a plate with a radioactive substance (UO2) that emits alpha or beta particle (In this case an alpha particle) and separate that plate from a second uncoated plate with a dialectic between them, it produces extremely high voltages (millions of volts) with very low amperage. This has a life span between 7 and 10 years.Provided you can drop the voltage with out adding excessive weight, it provides a lite weight unit with a high voltage to weight ratio.Being able to drop that voltage to around 30Kv means that the output from such a device could be used to power an Ion propulsion unit for long duration flight while keeping the overall weight of the craft to a minimum.So the question is can I find a way to reduce the voltage while keeping the overweight to a minimum? The DC to DC conversion from a buck converter showed some promise so I was examining it in more detail. I understand that it would not be done with small semiconductors, so I was trying to work out just how big it would need to be. It may be a dead end path but it was worth exploring.

author: danadak
author_rank: Super Contributor
timestamp: April 14, 2016, 12:38:44 am
content: Makes me wonder if you could do that by using a carbon nanotube to create a channelof atomic size to bring charge down to another plate, larger size. Not a physicist......An EE who barely knows what orifice to shove the soldering iron into.Q = CV, V = Q/CRegards, Dana.