Home
JAQForum Ver 20.06
Log In or Join  
Active Topics
Local Time 11:48 29 Nov 2023 Privacy Policy
Jump to

Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.

Forum Index : Electronics : Nano Power Inverter - Roll Your Own Style

     Page 2 of 16    
Author Message
Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 07:45pm 16 May 2019
Copy link to clipboard 
Print this post

  wiseguy said  
I went and fired up the circuit and took some scope shots.
The first shot is with no load, the nominal 12V was 18.1V. Loaded with a 220K it became 13.3V, 33K was 12.9V, 470R was 12.02 and 150R 10.9V

I am comfortable that the 2.5mA minimum of the FOD3182 opto will keep it well under control and around 12.5V. The UCC3080 driver seems well suited in this app.

Yup, that is pretty much what I was seeing.
In my case the required dc was +15v, and under no load conditions would reach about +20v.
I just added a 16v zener, and problem solved.

I would probably still be doing it that way if those little Chinese two dollar postage stamp power supplies had not become available.


Cheers,  Tony.
 
BenandAmber
Guru

Joined: 16/02/2019
Location: United States
Posts: 961
Posted: 08:24pm 16 May 2019
Copy link to clipboard 
Print this post

Hey warp speed if you get a chance could you put a link to the little postage stamp size power supply that you used

I would like to buy 5 or 10 of them just to have around

I've been Gathering up stuff for future projects

And another question do you use these kind of power supplies in your warp speed inverter
be warned i am good parrot but Dumber than a box of rocks
 
renewableMark

Guru

Joined: 09/12/2017
Location: Australia
Posts: 1677
Posted: 09:15pm 16 May 2019
Copy link to clipboard 
Print this post

If 65A will do these ar a lot cheaper
Cheers Caveman Mark
Off grid eastern Melb
 
Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 09:16pm 16 May 2019
Copy link to clipboard 
Print this post

These are the supplies Ben:

https://www.ebay.com.au/itm/New-AC-DC-Power-Supply-Buck-Converter-Step-Down-Module-5V-12V-3-3V-9V-24V-500mA/262807265342 ?ssPageName=STRK%3AMEBIDX%3AIT&var=561802963756&_trksid=p2060353.m1438.l2649
Cheers,  Tony.
 
BenandAmber
Guru

Joined: 16/02/2019
Location: United States
Posts: 961
Posted: 10:12pm 16 May 2019
Copy link to clipboard 
Print this post

The one that's a lot cheaper is a bolt down fastener

And unless I missed it the others are 24 volt DC or a hundred volts DC didn't say anything that will work with 48volts

I've looked pretty hard before I could have missed them but they're hard to find 48 volt ones

I picked a few wall warts up at the thrift store that works on DC but would like to find a cheap alternative

I plan on building one here soon if I find a good circuit diagram just to say I've done it before and for the experienceEdited by BenandAmber 2019-05-18
be warned i am good parrot but Dumber than a box of rocks
 
Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 10:48pm 16 May 2019
Copy link to clipboard 
Print this post

Those bolt down high current connectors look like really good stuff.
I have never used them myself, but only because I did not know about them.

They open up a lot of possibilities to run aluminium busbars raised above board level that can pass over the top of other tracks and even components.

Getting back to thermal design.
One idea I have used successfully, is to first bolt mosfets onto a copper block, then bolt the copper block onto the heatsink.

That is probably of very limited value if the back of the heatsink is really thick, say 10mm thick or more.

But if the heatsink is something like a very large flat sheet of 3mm aluminium, the thermal gradient right around the mosfet can be rather high. Something like a 50mm x 25mm x 3mm block of copper under the mosfet tab can make a significant difference to the heat flow path.

This is the last remains of a very old project that shows the idea:





Cheers,  Tony.
 
LadyN

Guru

Joined: 26/01/2019
Location: United States
Posts: 408
Posted: 12:55am 17 May 2019
Copy link to clipboard 
Print this post

Instead of bolting directly to aluminum, using copper intermediary is to help dissipate heat better?

(Copper has a higher thermal conductivity)

How much of a change does this have on the life/performance of the MOSFET?
 
Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 02:10am 17 May 2019
Copy link to clipboard 
Print this post

Without the copper, all the heat concentrates into a very small area of some fairly thin aluminium. With a copper plate, the heat is spread over a far wider area into the aluminium.

[quote]How much of a change does this have on the life/performance of the MOSFET? [/quote]

Probably not much, unless you are really pushing the absolute limits of junction temperature. I suppose it depends on your appetite for risk.
Cheers,  Tony.
 
BenandAmber
Guru

Joined: 16/02/2019
Location: United States
Posts: 961
Posted: 02:14am 17 May 2019
Copy link to clipboard 
Print this post

God bless Australia a big thanks to all you guys down under

I was reading somewhere that the legs of a mosfet got the hottest Warpspeed could probably fill us in on that one

And another silly thing I've been thinking about is putting the whole board in Transformer oilEdited by BenandAmber 2019-05-18
be warned i am good parrot but Dumber than a box of rocks
 
BenandAmber
Guru

Joined: 16/02/2019
Location: United States
Posts: 961
Posted: 02:30am 17 May 2019
Copy link to clipboard 
Print this post

Sorry if I've gone off topicEdited by BenandAmber 2019-05-18
be warned i am good parrot but Dumber than a box of rocks
 
kentfielddude
Regular Member

Joined: 09/05/2019
Location: United States
Posts: 89
Posted: 02:41am 17 May 2019
Copy link to clipboard 
Print this post

Silver is the best thermal conductor. This heat sink should ensure you don't run into any overheating issues.

 
Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 04:31am 17 May 2019
Copy link to clipboard 
Print this post

Everyone should own some silver............................

Cheers,  Tony.
 
wiseguy

Guru

Joined: 21/06/2018
Location: Australia
Posts: 907
Posted: 08:14am 17 May 2019
Copy link to clipboard 
Print this post

  renewableMark said   If 65A will do these ar a lot cheaper


Hi Mark, Thanks for your interest and suggestion, I did a complete survey of Ali when I chose the connectors. For the Battery & Choke connectors I am going to use tinned red copper solderable lugs they are 1.5mm thick, the ones you suggested are 0.8mm tinned brass and they worried me a bit for higher currents, but I welcome suggestions like this !
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
wiseguy

Guru

Joined: 21/06/2018
Location: Australia
Posts: 907
Posted: 08:29am 17 May 2019
Copy link to clipboard 
Print this post

  Warpspeed said   Those bolt down high current connectors look like really good stuff.
I have never used them myself, but only because I did not know about them.

They open up a lot of possibilities to run aluminium busbars raised above board level that can pass over the top of other tracks and even components.



I agree the copper suggestion would draw in and spread out heat the best, but in the past I have found it difficult to tap. Is it easy to buy in bar form and I imagine fairly expensive? If it ever comes to immersing my electronics into transformer oil to keep it cool I'll take up another interest, that doesn't even rate as a last resort. I might consider a radiator and circulating liquid through tubes and a thermal exchanger with FETs on it but that would be my last resort.

Its no coincidence that the standoffs are all inline (~10mm high) I already pictured a long copper or aluminium bar from end to end, tap them in the centre for M5 or 6 and bolt the power inputs directly to the middle of the bus, lots of options.

If the HY4008's are happy in parallel without oscillations they can be bolted direct onto aluminium Bar I have lengths of 25 x 10mm xsection with one long and 2 shorter pieces. The long one is the + connection, the shorter ones are the choke connections again if tapped you could bolt directly to them. Then with strips of silicon pad bolt the Bars to a heatsink (with insulation for the bolts) and we have better thermal behaviour than individual pads on the FETs. All this fun still to be had......Edited by wiseguy 2019-05-18
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
wiseguy

Guru

Joined: 21/06/2018
Location: Australia
Posts: 907
Posted: 09:32am 17 May 2019
Copy link to clipboard 
Print this post

  BenandAmber said   I also read a article that said legs of mosfet get the hottest

And that you should put them down in the bored as close as possible

Then I compared the size of the legs of the smaller mosfet and the larger ones

The larger mosfet has much larger legs and if the legs are what gets the hottest it would seem to me the larger mosfets are better

What do you think Wiseguy and Tinyt

Would value your thoughts on this


I prefer the bigger FETs when dealing with lots of energy & current. There are some pretty amazing TO220 mosfet specs but it doesnt sit comfortably with me when you put them alongside a TO247 package - cause they look tough! I have not used any electronic engineering data to back this up, consider this a gut feel or anecdotal assessment!

I also like the mounting of TO247 and the surface area for heat transfer and yes the legs are much more substantial - If I have the space I will use TO247 any day.
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
BenandAmber
Guru

Joined: 16/02/2019
Location: United States
Posts: 961
Posted: 05:37pm 17 May 2019
Copy link to clipboard 
Print this post

That gut feeling means a lot coming from you WiseGuy

By the way I appreciate the advice you gave me a when I first came on here

And I've read a few post that you commented in

I can see you definitely do not need to have a board in your hand or even see a board for that matter to know how it works
be warned i am good parrot but Dumber than a box of rocks
 
wiseguy

Guru

Joined: 21/06/2018
Location: Australia
Posts: 907
Posted: 06:15am 22 May 2019
Copy link to clipboard 
Print this post

Ok now for some transformer discussion on my ebay purchase. The ad reads "5000W 240AC to 38V 80A toroidal transformer" 2 available. Here is a picture from the AD.



Other text from the ebay posting read:
Transformer removed from working device (LF 10000W off-grid inverter).
230VAC to 32VAC/80A
240VAC to 38VAC/80A
or
32VAC to 230VAC/16A
38VAC to 240VAC/16A

Size: D170 x H100 mm

Weight: 10 kG

I emailed him suggesting there is an issue with the text in the ads.
There are 2 wires for primary and 2 for secondary - no taps.
It cant be 230-32 & also 240 - 38, they are different ratios. I also pointed out that ot cant be 5kW and also 32V x 80A as that is only 2.56kW. Also 230 x 16A = 3.6kW.

The transformer finished dimensions are actually closer to OD 160mm, ID 55mm, H 90mm.
Weight is ~ 9.7kG

Compared to an Aerosharp I have is OD 195mm x ID 55mm x H 70mm. weight 11.2 kG.

I suggest that the sticker is either 5kW for both transformers or a peak value for 1 transformer it just doesnt feel like a 5kW toroidal. The cost was $180 for the 2 delivered.

I ask for comments, the transformers arrived yesterday I brought 2 hoping for the 10kW in the AD but I have a gut feel these are only good for 2 - 3 kW each. I will post the test data soon which is excellent. But do I complain about them or just let it slide and accept them for what they are ? I am disappointed but also know the value I paid is probably about right even if they are only good for say ~ 6kW in parallel ? Test data posted shortly.


Edited by wiseguy 2019-05-23
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
renewableMark

Guru

Joined: 09/12/2017
Location: Australia
Posts: 1677
Posted: 06:37am 22 May 2019
Copy link to clipboard 
Print this post

how much were they?

Cheers Caveman Mark
Off grid eastern Melb
 
wiseguy

Guru

Joined: 21/06/2018
Location: Australia
Posts: 907
Posted: 07:12am 22 May 2019
Copy link to clipboard 
Print this post

Hi Mark I edited it after you read the post as I realised I forgot to say, $180 delivered for the 2 toroids.Edited by wiseguy 2019-05-23
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
mackoffgrid

Guru

Joined: 13/03/2017
Location: Australia
Posts: 460
Posted: 07:13am 22 May 2019
Copy link to clipboard 
Print this post

Mike, I think you did fine, as long as you don't have to modify them.

2 x 9.6kg wound transformers for $180 -

Yes, I'd agree that you've got 2500ish VA. Do your testing with them and if you need to do larger, sell them off to someone who really can't handle the transformer winding.
 
     Page 2 of 16    
Print this page
© JAQ Software 2023