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flyingfishfinger
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Joined: 12/09/2020
Location: United States
Posts: 110

Posted: 08:50pm 01 Jun 2021

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Hi all-
Been thinking about this for a while and I can't really figure out how to proceed. Since I'm starting to make some progress on the DIY MPPT for my PV, I was going to just build a 2nd one for the micro hydro while I'm at it.

However, it's become clear to me that the input voltage options complicate this somewhat for the latter.

Basically, the unmodified F&P outputs 380V AC, 3-phase, unloaded. I'd like to keep it unmodified so I don't lose too much power between my water location and the battery, which are at best ~200 feet apart.

If I rectify this voltage, I'll end up with a max of over 500V DC that I don't quite know what to do with unless the MPPT can be built with IGBTs to handle this much input.

I've put an alert on Ebay & Craigslist for 3-phase tranformers, but those are rare and very pricey in the ~500W power levels.

What other options do I realistically have here?

R

Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406

Posted: 09:09pm 01 Jun 2021

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It will only generate 380v at flat out maximum rpm. I have no idea how fast the spin dry cycle is on the highest of the three speeds, but its fairly fast.

Output voltage will be proportional to rpm, so the actual voltage you end up with will probably be a lot lower. A lot also depends on the circumference of your hydro and how fast the water speed.

Best to just put it all together and run some tests and see what you get. Then change things accordingly. Too many unknowns at this stage.

Cheers, �Tony.

flyingfishfinger
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Joined: 12/09/2020
Location: United States
Posts: 110

Posted: 09:12pm 01 Jun 2021

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Warpspeed said Output voltage will be proportional to rpm, so the actual voltage you end up with will probably be a lot lower.

I did this test at 500RPM. Even if the actual use case IS much lower, shouldn't the system be designed to handle the no-load case for safety? That's what I'm asking about, effectively.

But yes, next opportunity to take measurements is in a month - just trying to plan ahead best I can.

R
Edited 2021-06-02 07:15 by flyingfishfinger

Murphy's friend

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Joined: 04/10/2019
Location: Australia
Posts: 648

Posted: 08:12am 02 Jun 2021

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Can you put a centrifugal brake on the shaft?

BenandAmber
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Joined: 16/02/2019
Location: United States
Posts: 961

Posted: 09:08am 02 Jun 2021

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Keep in mind I am just a monkey see monkey do jack leg among giants on this forum

I have gave a similar thing some thought

I have several similar motors

I have been debating with myself to use one or two of them for a windmill

Or to use a 2 to 3 hp 3 phase induction motor that I made into a alternator

I turned down the rotor just enough to add small high temp motor magnets to it

The small rectangular magnets are in rows to exactly cover just the iron part of the rotor

I tried to make it just like I imagined it would be magnetized by stator when running as a motor

It does a really amazing job when turned or just rocked back and forth with two fingers

It will light up a large led flood bulb or a regular filament bulb out of a old microwave

My thinking was the permanent magnets would start a currant in the stator at low speed when driven as a alternator

This current in stator would then cause the iron core of the rotor to become magnetized adding to and becoming much greater than the small permanent magnets

My thinking was it would have low to no cogging because of the small magnets

Then as the rpms go up so would the strength of the magnetic field in the rotor

I always have several projects going on at one time and haven't made it back around to testing it

I wrote about it because testing it turning by fingers or hand seem very promising

If my hair brained induction magntizing rotor at low speeds idea doesn't work out

I still think big strong magnets on a three phase motor that the original rotor has diagonal instead of straight lines would make a very good choice for home made alternator

That's what run on sentence should look like lol still king lol

The rpms and the resistance of the load will determine the voltage and amperage of the output of your alternator motor

Fisher and Paykel Samsung have many poles

When running as a alternator the rpm along with numbers of poles will determine the Hertz of the ac output

The number of north south poles for one complete turn and the rpms determine the Hertz

The higher the frequency Hertz the smaller the transformer can be for the same wattage amps volts watts

This may have to be considered when choosing one bigger or three smaller trannys to step down the three phase ac voltage

Regular transformers laminated steal or iron that are used at 50 or 60 Hertz are not good for alot higher frequency or herts

They will loose energy by heating up

This is called over saturation

Some say only frequency causes saturation

Others say current can cause saturation

My hair brained thinking thanks that the higher the amperage magnetic the lower the capacitance voltage

When one rises the other falls

when the capacitance and inductance are turned perfect in the choke to absorb the flip-flopping

you won't see any ac voltage on the battery cable going to your inverter

capacitance in the non-magnetic and amperage in the magnetic

this is my understanding what is happening in a inverter choke

I would like to read a back and forth between the greats on here about it

The material the core is made of determines how high the frequency can be

The higher Hertz transformers are usually some type of ferrite

Alot less magnetic but much higher in capacitance when voltage is flipping

if you want lots of energy you think big but it is truly in the small or not here at all or we could be swimming in it
but don't know it like a bird on a wire lol

There are countless mixtures of ferrite cores made

You have to pick the one best suited for the job

To pick the best one best suited you must know the voltage amperage frequency "herts"

And all of these will change when the load or resistance changes

So this comes right back to the answer you was already given by a great lol

Now if you really want to do something find a way to keep the load from affecting the rpm no cogging or back emf

You can change the phase angle with respect to time like to add a phase to a motor by adding a capacitor

The two parts that make up electric do not travel at the same speeds

This can be proven with many capacitors and inductors in series and parallel configuration

two rows of capacitors connected end to end with inductors connected in between like runs of a ladder across the two rows of capacitors

Or you can hook the inductors in two long rows and the capacitors being the runs of the ladder

This proves you can slow down or speed up each of the two parts needed to have electricity

The magnetic is the amperage it spirals down the line the capacitance is the voltage part it goes straight

When you short out a coil of a tranny the voltage drops and amperage goes really high

the tranny may even jump around if really bad you may need a clothing change

when you open a switch the voltage rises high enough to jump through air
as a spark

the higher the magnetic or amps and or voltage on the line of the switch being opened the bigger the spark

The voltage will continue to rise to Infinity if it had to to let the magnetic get out

This different speeds happens 24 7 on the grid

This along with high voltage maybe how the grid overcomes the massive amounts of resistance in every foot of wire from Power Station to where the power is used lol

Now keep in mind any of the above info could be wrong this is just my understanding

I really like it when I am wrong this means I am getting a more accurate understanding of the relentless never ending search for how things truly work

Thanks for your time
Edited 2021-06-02 20:12 by BenandAmber

be warned i am good parrot but Dumber than a box of rocks

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