Big Mill, 90vdc gearworks motor, HOW TO CORRECT REVERSE POLARITY when MILL TURNS BACKWARDS??? DC to AC to DC?

[farmhand]

Hi all!
So we have a 6' HeAvY windmill 30' to the shaft. It is fixed facing west (prevailing wind in central Ohio). 90% of the time she spins "forward", but 10% of the time it does spin in "reverse".
There is a 35-chain sprocket & V-belt puller on the end of the shaft. I plan to chain this (after a ratio change) to a Gearworks 90vdc motor I have. The motor will be down around 15' where I can easily maintain it & lube the chain. By the number this motor will work perfect for the Eco Max's 11v-100v input. This will work well for our cabin's 250w idle draw overnight, as when this was once a stand-alone wind-generator it averaged 300-500w.

But, the first round was an alternator where the load would stall the mill at <7mph wind. This DC motor will not being the Eco Max caps off at 800watts..........


But HOW would I best avoid this reverse polarity issue by either (A) changing it back automatically, or (B) have the circuit open in a reverse polarity condition?
I can only think DC to AC to DC... but that's a lot of loss.
Diodes: My 6-string array all have reversing diodes in the PV combiner box (due to partial shading at times), so (C) Would I need a reversing diode for the mill as well? I figure as the mill output will also tie into the array output.... then the array would power the DC motor and turn the mill into one big damn fan.....

This is a lot to consider but now having the Eco Max for a few days we're REAL close to running 24/7 offgrid if I could get this mills little bump in power.

(The tail shown in a pic below is no longer on it, it looked COOL as all get out slowly rotating off the shaft... then winds came from the side during a storm, and every 90degrees rotation would put massive drag, then zero drag on the shaft that is fixed to the tower. These towers flex a little, but we saw the top of this tower seriously rotating 6" north from center, then 6" south of center on the horizontal plane. It was scary & something to see... things we learn but it didn't come down :D)

REALLY looking forward to some feedback from you all, thanks!

 

[v_green57]

Bridge rectifier:

Reverse Polarity Protection | REUK.co.uk

Corrects reverse polarity when used as shown. Schottky diodes minimize losses due to forward drop.

I used to use bridges to protect solid state RF amplifers which were prone to being hooked up backwards in vehicles by inept end users.

 

[farmhand]

Bridge rectifier:

Reverse Polarity Protection | REUK.co.uk

Corrects reverse polarity when used as shown. Schottky diodes minimize losses due to forward drop.

I used to use bridges to protect solid state RF amplifers which were prone to being hooked up backwards in vehicles by inept end users.

Maybe, not seeing any DC/DC options that will handle up to 1500w (which is rare but in 60MPH winds that massive rotor is up to a scary 80RPM).

My first thoughts are two DC ice-cube relays: Where correct polarity closes Relay (A) connecting to the Eco input, and reverse polarity closes relay (B) which will be wired to correct the line power to the Eco.
....... hmmmm

 

[winny]

Maybe, not seeing any DC/DC options that will handle up to 1500w (which is rare but in 60MPH winds that massive rotor is up to a scary 80RPM).

You don't need a DC/DC, just a bridge rectifier. Aim for 2x peak current rating and 2x peak open circuit voltage to be on the safe side. Bridge rectifiers are dirt cheap anyway.

 

[v_green57]

Maybe, not seeing any DC/DC options that will handle up to 1500w (which is rare but in 60MPH winds that massive rotor is up to a scary 80RPM).

My first thoughts are two DC ice-cube relays: Where correct polarity closes Relay (A) connecting to the Eco input, and reverse polarity closes relay (B) which will be wired to correct the line power to the Eco.
....... hmmmm

The bridge should do it. You just need to find one that has the requisite current and voltage rating. Or build it yourself out of individual diodes.

Power dissipation will be minimal - whatever current you're pushing X .3V (forward drop for Schottky diodes).

 

[farmhand]

Next question.... how would the Eco's MPPT charger react to this? I can't see any issue but..... ?

 

[v_green57]

Next question.... how would the Eco's MPPT charger react to this? I can't see any issue but..... ?

Weeellll...if its MPPT algorithm is well written (not all are - esp. the AIO's), it should just see another variable DC source to charge with.

Think of a day with puffy clouds intermittently shading the panels causing output to go from 0 to max. over and over.

 

[Warpspeed]

Just fit the bridge rectifier and the job is done.

 

[farmhand]

Just fit the bridge rectifier and the job is done.

The chain shows up today, will get it generating Monday & will report back

Here's a link of the rectifiers I bought: https://www.amazon.com/gp/buy/thank...09833&ref_=chk_typ_browserRefresh&isRefresh=1

New Question: What happens to the Eco is I have say 30vdc on the input line while the array 80vdc is also on the line? Would I need to have a photocell control to only connect the mill power after dark?

 

[winny]

The chain shows up today, will get it generating Monday & will report back

Here's a link of the rectifiers I bought: https://www.amazon.com/gp/buy/thank...09833&ref_=chk_typ_browserRefresh&isRefresh=1

New Question: What happens to the Eco is I have say 30vdc on the input line while the array 80vdc is also on the line? Would I need to have a photocell control to only connect the mill power after dark?

Link does not work for me. Can you post make and model?

 

[farmhand]

Link does not work for me. Can you post make and model?

Sure, sorry for the wrong link, here's a good one.

HiLetgo 10pcs KBPC5010 Diode Bridge Rectifier Diode 50A 1000V KBPC 5010 Power Rectifier Diode Electronic Components​

https://www.amazon.com/dp/B07WBVTQR2?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

[v_green57]

Sure, sorry for the wrong link, here's a good one.

HiLetgo 10pcs KBPC5010 Diode Bridge Rectifier Diode 50A 1000V KBPC 5010 Power Rectifier Diode Electronic Components​

https://www.amazon.com/dp/B07WBVTQR2?psc=1&ref=ppx_yo2ov_dt_b_product_details

Damn, that's cheap. I am skeptical...

Also, even though Amazon says:

"Amazon's Choice in Schottky Diodes by HiLetgo"

I am pretty sure that's wrong, and it's just standard silicon. See attached from the data sheet. The Vf for a Schottky device would be about 0.3V.

Amazon tends to make errors in their advertising blurb when they don't really understand what it is they're selling.

There's no technical reason this won't work, you'll just be losing a little more power.

 

[Warpspeed]

That is a standard low cost ordinary diode bridge, definitely not Shottky, but it will definitely work when fitted to a reasonable sized heat sink.
Its going to drop 1.5 to 2 volts though.

If it solves your problem, as I expect it should, you can then replace it with four proper (more expensive) Shottky diodes later on.

 

[farmhand]

Damn, that's cheap. I am skeptical...

Also, even though Amazon says:

"Amazon's Choice in Schottky Diodes by HiLetgo"

I am pretty sure that's wrong, and it's just standard silicon. See attached from the data sheet. The Vf for a Schottky device would be about 0.3V.

Amazon tends to make errors in their advertising blurb when they don't really understand what it is they're selling.

There's no technical reason this won't work, you'll just be losing a little more power.

Thanks V & Warpspeed. I don't care much about a few voltage drops, like you said I can upgrade it once it's functioning the way I want.

Questions remain:
What will the EcoDelta MPPT do if I have 40v & 80v on the DC line during the day.... hmmmm.....

I'm thinking have the windmill charge a bank in the outhouse & have these batteries available to recharge the Eco. This is likely safer.

 

[Warpspeed]

As far as a heat sink goes, just bolt it to some convenient structural steelwork through the hole in the middle.
That is all you need.