Parallel operation of DS-DS converters. - Page 1
Forum section: electronics / general

author: MikeP
author_rank: Regular Contributor
timestamp: May 05, 2023, 08:35:22 pm
content: Hello.Suggestion from a colleague. Instead of one powerful converter, use three or four low-power ones. Yes, connected in parallel. Only four channels, respectively up to 16 modules. We are talking about a total power of about 250 watts. Here are examples of Isolated Modules. Nothing unusual:https://www.digikey.com/en/products/filter/dc-dc-converters/922?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALGGABxwDsIAuoQA4AuUIAyuwE4BLAHYBzEAF9CtAMyIQKSBhwFiZENJhgArACZGLEBy69BoiYS31Z0eWix5CJSOT01aMZm06Qe-YWMlwCnoIGwUlB1VncDAYLQAGBAMjHxN-c3A4Ojlw%2BxUncnjmQJ1aRhsUkABVIQF2AHlUAFlcdGwAVz5cEEJ2rgB1HpAAW2EubSHh9AAPLmkiktLQ5DtlRzUIZO8QAEkhdlwRXD4MgFodHKh%2Bdvy1LWKStQATJFOXgAIkIiEAN2ODk4Ge4VKBgNisUHxeKBDw2ARPLinMDxCBeLhDdgAT1Y3R8bRQ4nEQAI ask you to list all the possible disadvantages of such a design.Thanks.

author: Faringdon
author_rank: Super Contributor
timestamp: May 07, 2023, 12:17:37 pm
content: Vicorpower sell "array" power modules, which can be paralelled.But yes, this course has a folder called "parallel SMPS", and you can look in there about it.Give me a shout if you dont find it..https://drive.google.com/file/d/1WvElhDNfHI0EBei4rouSNEdWWTO1oCtJ/view?usp=share_linkalso folder called "Low Vout high current SMPS" has details on paralleling.One disadvantage is one of them can serve all the current, and the other , none......but there are ways to get round this...eg share chips, master slave method, droop method, etc etc.If the output is current regulated, then it is no problem, paralleling them.In that course, there is some sims of load share cuircuits, to help psu get paralleled...give me a shout if you dont find.

author: MikeP
author_rank: Regular Contributor
timestamp: May 07, 2023, 03:15:34 pm
content: Well. Here are the shortcomings that I see:- power losses on current-leveling resistors. As an example, the accuracy of some Cui modules is +/- 3%.- there is no way to synchronize the modules, so we get an unpredictable interference pattern.- a noticeable volume will be stolen by unnecessary cases and duplicate pins. Besides, you have to pay for all this.- finally, I have no idea about the content of the modules and the reliability of this content. This point should be multiplied by 16.

author: Faringdon
author_rank: Super Contributor
timestamp: May 07, 2023, 03:26:25 pm
content: Thanks, they have output caps, so beating shouldnt be that bad.If you want, you can just put a current clamp on the output of each smps....then at least none will end up giving more than their rated current.

author: ejeffrey
author_rank: Super Contributor
timestamp: May 07, 2023, 05:07:50 pm
content: Paralleling 16 20W modules to reach 250 watts seems completely bonkers to me. 250 W modules are easily available and should be smaller, cheaper, more efficient, and more reliable. Parallel operation is normally done with much larger individual modules either where a single unit is impractical or the system is designed for n+1 redundancy.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 11, 2023, 07:38:44 am
content: Just don't parallel generic voltage sources. You need significant amount of balancing resistance which wastes a lot of power, creates problem of heatsinking, and regulation goes to crap. If you use ambitiously low balancing resistances, you get reliability problems at it seems to work but then does not when temperatures change or devices age. Besides, there is no point, as suitable size of converters are easily available.Now some supplies support paralleling and then it's totally fine. Paralleling power stages is also excellent design practicewithina supply, there just needs to be per channel current control so that current is shared properly.