Everyone seen this? More efficient alternator

[oil pan 4]

I am sticking with the big alternator.
Solar doesn't do me any good when its thick over cast and I am trying to run the electric power steering (when I hook it up),defroster, washer fluid, heater and lights or the power inverter.

I have a spare AC delco alt I can take apart to see if its feasible to remove/bypass the existing diodes.
If I remember correctly this alt wasn't coming up on voltage like it should.

[oil pan 4]

I took my old alt apart.
I can completely reengineer this thing.
Convert the stator windings from 3 wire to 4 wire wye. I can see where the wires come together and I can access them.
Whats the difference between 3 and 4 wire? By adding a current carrying neutral wire I can increase stator capacity by about 70%. Decrease the working load on the line diodes.

Then add a PWM controller or resistor to the Vreg power source to slow the charging rate if I want to.

Add a pot to the Vsense terminal to turn up the volts if I so desire. On the big old generators which had a voltage reg not so unlike this one they typically used 0 to 50 ohm pots to fine adjust the voltage.
So I figure stick with what works and get a 0 to 50 ohm pot to put on there.

The wires that make up the stator are 16 or 18 gauge, so there is no way each wire is holding 100+ amps RMS. Those wires would just melt.
20 or 30 amps per line max (if it were to stay a 3 wire).

I ordered 25 of those Texas instruments Schottky diodes. $90 after shipping and sales tax.
All I can do is give it a try.
There might be a few other projects I can try them on so I ordered some extras.
It looks like their normal application is solar panels. When I get solar panels in I take off reverse blocking diode. Because I use a charge controller and I am not worried about losing a little bit of power if some of the panels become shaded. I would rather get that extra half volt all the time and lose a few watts some times when some panels become shaded. Instead of losing that half volt all the time, just to save a few watts if some panels become shaded.

A more economical solution for under driven alternators might be to just install 3 of these shcottkys between the stator and the voltage regulator.

[serialk11r]

Originally Posted by oil pan 4

A more economical solution for under driven alternators might be to just install 3 of these shcottkys between the stator and the voltage regulator.

I think the most cost effective way to do this if you don't want to cough up the money to replace all 6 diodes is to replace only 3 of them. That cuts the voltage drop in half, for 20-30 dollars. Should give an extra bit of power at low speed.

[aerohead]

Originally Posted by Photonfanatic

Can you expand upon that explanation? I'm a bit of an electricity noob and what you're talking about sounds interesting. Are you making a way to make the standard alternator more efficient?

GOOGLE: Field-effect transistor
look at MOSFET and IGFET.
Very efficient,low loss power transfer

[oil pan 4]

I am thinking take this:


And modify to this:


I will be putting the rectifiers out side of the housing, outside of the hood where they can stay cool since these schottky diodes are only rated to 125'C and things that alternators are typically made of are rated up to 200'C.
Silicon diodes are good at elevated temperatures.

VR is where I can fine tune the voltage at the battery with the Vsense wire.
Vsense is for use with the LiFePO4 and power inverter setup, to provide boosted voltage level at point of generation to provide proper voltage to the battery during heavy inverter use.
The switch labeled swF kills power to the exciter field.
In the stator I will utilize the 4 wire wye configuration.

[freebeard]

Have you tried the folks in the Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control thread? Or Open ReVolt: open source DC motor controller? They live for that stuff.

[oil pan 4]

I got the diodes in and they are tiny.
This will make heat sinking them a little more difficult.
They are about the size of a single 555 timer.

I think my best chance is to solder up the 4 wire bridge rectifier which is going to be a mess and encapsulate it.
I have some leftover silicone based solar panel epoxy I could use for this.

The way I figure it each of the 4 wires will have to handle about 35 amps RMS at full power. So each wire that will be soldered into to the alternator windings will be at least 12 gauge.
Which is what I see a lot in vehicle alternator to welding alternator conversions.

[serialk11r]

Old thread but I was thinking about this again today, even though I have no car. I was thinking how I'd hypothetically go about increasing alternator output for minimal effort if I were to change a bunch of accessories on an older car to electric.

I noticed it's pretty easy nowadays to find pretty low RDS_on MOSFETs with synchronous rectifier controller on a board like this: https://www.ebay.com/itm/15A-50A-Ide...e/153280765383

At 1.5mohm, you're looking at about 0.34V drop across two in series, and 40W/6=6.666W heat dissipation at 120A output, which seems manageable with some small heat sinks.

I'm not sure if those switch fast enough though. An alternator at 16000rpm with what, 6, 8 poles? would would switching at about 1000Hz. I kind of ran out of energy looking at MOSFET specs trying to figure out if the gate capacitance would be an issue.

There's also this: https://www.mouser.com/ProductDetail...020DyZ8w%3D%3D

It seems like it can handle 80A at 50% duty cycle square wave, equivalent to 80*sqrt2=113A continuous in terms of heat dissipation. A 150A rated alternator would see a 106A amplitude 50% duty cycle square wave which is below that, and the voltage drop across two of these things would be about 0.6-0.8V, which is not too bad. Since they're less bulky, wiring them up might be easier, but they need more heatsinking.

In the second case, the voltage drop is being cut by a bit over 1V compared to a normal alternator rectifier. That gets probably something like 10A for free, which is just about enough for an electric power steering pump at idle + electric water pump

[teoman]

Tvago was working on something like this but he has not been active for some time.

[Tahoe_Hybrid]

Originally Posted by Photonfanatic

Alternator 3500 & 6200

If you look at the bottom of the page, these guys claim that the minimum, you'll see a 5% increase in efficiency using their alternator as opposed to the standard kind. Anyone used one of these things? Sounds like it could be well worth it, in the long run.

Chevy Tahoe alternator from 2008 and up has manual power control (elerto magnet )