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Forum Index : Electronics : 150V 45A MPPT - roll your own

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Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4384
Posted: 01:20am 11 Oct 2021
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How's the back Peter ?
Cheers,  Tony.
 
poida

Guru

Joined: 02/02/2017
Location: Australia
Posts: 1084
Posted: 02:49am 11 Oct 2021
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Better each day. I need to be able to work tomorrow. And fold in 1/2 to get in the
MX5 to drive to work. I don't think it was a disk, I think only muscle strain.
wronger than a phone book full of wrong phone numbers
 
Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4384
Posted: 02:54am 11 Oct 2021
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A soak in really hot bath usually works for me for those types of problems.
What MX5 do you drive ?
I have a a white 99' NB1
Cheers,  Tony.
 
poida

Guru

Joined: 02/02/2017
Location: Australia
Posts: 1084
Posted: 10:11am 11 Oct 2021
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Warp:
A 99 NB with 310,000km on it, broken everything but it runs. And leaks a bit of
oil out of all ends. Busted bodywork but that suits me nicely.
I get free fuel from work and I have had the car since 2005 so it costs me
not much more than $1K per year.
I am now thinking of a KTM RC390 motorbike. Already I have
a 900 Superlight Ducati but the KTM seems a good fit for getting to work.

Anyway, back to the subject at hand..

The damage to the screwdriver:






All in the name of science. (as Photinicinduction would say)

Code changes now look for a short and modify the PID loop
whilst shorted. This prevents voltage overshoot when the short is removed.
This is a great start for a home brew big current, big voltage power supply
for the bench and ebike charger.
I want well over 60V and 20 Amps and for it to be indestructible.
wronger than a phone book full of wrong phone numbers
 
noneyabussiness
Guru

Joined: 31/07/2017
Location: Australia
Posts: 389
Posted: 09:42pm 13 Oct 2021
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reminds me of the time I dropped a screwdriver on a 48v bus bar before the fuses... literally made the section between contact points disappear,  never found it..

and it was a big screwdriver...

lesson learned,  moved + and - much further apart..
I think it works !!
 
poida

Guru

Joined: 02/02/2017
Location: Australia
Posts: 1084
Posted: 06:33am 14 Oct 2021
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Noneya, big current can be impressive.
And when it's DC, it is even a better show.
My only, so far, mistake was to let a nice 13mm ring spanner
short a + and - on a 4 x 200AH SLA bank at 24V. It only just chewed
a little off the side of the handle.

During testing of the above, I had the firmware not looking for short circuit
and just trying to attain the voltage setpoint, while the FET/current sensor thing
was doing it's thing.
I could set the OC protection to about 35 Amps and let the screwdriver graze
a conductor and nearly maintain an arc. 35 Amps at less than 0.5V is not impressive
but it still bites a hole in the metal.

All this and not blowing up 2x nice MOSFETs.
Maybe I could adapt this to be a TIG welder..probably not.
wronger than a phone book full of wrong phone numbers
 
poida

Guru

Joined: 02/02/2017
Location: Australia
Posts: 1084
Posted: 10:57am 01 Nov 2021
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Milestone time again.
I must again thank you all here for your help in developing this project.

I run two of these mppt controllers.
One has a 3kW array facing East
One is 3kW facing North.

The East facing array:



and the North facing array:



They just work and work well.

3 MW.hr of energy has passed through them.
And with an efficiency better than 92%, frequently
in the 95%.

Heat sink temps never more than 35 - 40 C
The North array mppt controller gets to 45 Amp limiting conditions
often, but for short periods of time now it's nearly Summer.
wronger than a phone book full of wrong phone numbers
 
poida

Guru

Joined: 02/02/2017
Location: Australia
Posts: 1084
Posted: 04:10am 26 Jan 2022
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Today it is hot.
the mppts are working well and I have one doing a lot of work
and so the heat sink is getting hot.
I have the output current throttle setting to start at 55 DegC
to reduce output current limit from 45 Amps to zero Amps at 65 degC

It works well. We can see the output limit become lower as the HS temp
exceeds 55 degC and the output current flow suit, never exceeding it.
It's also a bit cloudy so there is not enough power
some times.

data from today so far:
output current is Green
Heat sink temp is Purple
Output current limit is Orange


wronger than a phone book full of wrong phone numbers
 
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