Solar hot water pumps, - PV array sizing & BLDC pump

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bobc
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Solar hot water pumps, - PV array sizing & BLDC pump

Postby bobc » Mon Jun 23, 2008 12:29 pm

A colleague at work has put a PV powered electric pump on his roof mounted solar heating array. From ebay he got an array of parts including a small BLDC pump and a £50 PV array (12W).
It didn't work - the array voltage just collapsed with the pump wired in. He was going to buy a bigger PV array, but I suggested that the problem might be tha pulsed current taken by the pump & that a capacitor might solve the problem. To my great surprise, I was right! A 2200uF capacitor across the output & it pumps like billyo - saving him a further £50 bill for more solar cells.

Deker
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Solar

Postby Deker » Wed Jul 02, 2008 1:55 am

bobc says "a small BLDC pump"

Whats a BLDC pump, Bob ?

Deker.

bobc
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Location: Knutsford

Postby bobc » Wed Jul 02, 2008 9:49 pm

BLDC = brush less DC motor

MalcolmB
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Postby MalcolmB » Thu Jul 03, 2008 3:48 pm

Hi Bob
So is the pump being driven without a controller? Brushless motors are usually three-phase aren't they. How are the individual phases connected to the array?

bobc
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Location: Knutsford

Postby bobc » Wed Jul 09, 2008 3:44 pm

Hi Malcolm
The pump runs from a nominal 12V DC - it has internal electronics to do the commutating. It's a cheap 12V pump from ebay intended for automotive use.
It is just stuck straight across the PV array. The array output can go up to 17V on load I think, but car stuff is designed for 14.4V continuous & 42V surge so it should manage. The PV array has quite nice gentle supply characteristics ;^)

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ChrisB
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Postby ChrisB » Wed Jul 09, 2008 10:00 pm

What a cracking tip Bob .....nice one

ChrisB
I reject reality and substitute my own !!!!!!


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