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PMA to an Inverter, Project woes

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discogodfather

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I recently got a small permanent magnet alternator online. It's only advertised specs are a series of power ratings at speeds, this one is supposed to produce 100w at 3000rpms, around 20-30v. It's single phase and has two wires.

My project goal was to take this PMA and drive it at 3000rpm's and try and see if I could get useable 120vac from it. I started by grabbing a full wave bridge rectifier (rated for 30 amps) and got the setup to produce 20-30v DC. Then I took a DC to DC converter (uses a Buck Boost curcuit) to take the 20-30v and convert it to a solid 12v.

From there the system is connected to a 100w pure sine inverter. Everything starts up fine and my meter reads 120vac. I am looking for my scope to verify the wave, but the inverter is a good quality samlex.

Now comes the PROBLEM! When I attach a load the whole system shuts on and off rapidly. Voltage drops hard from the PMA (around 10-15v) and the dc to dc converter looses its 12v, sometimes dropping below 10v. The inverter beeps and turns on and off. I have been careful to only apply resistive loads (no capacitive and inductive) mostly 15, 40, and 60 watt incandescant bulbs. They seem to light up to nearly full brightness but only stay on for a moment, then on and off rapidly. There is an RPM drop under load but I end up compensating for that and it dosen't solve the problem.

I can't seem to find anything on similar projects on the web and fear my ignorance is getting the better of me- is it possible to get decent AC power directly from a PMA? Most people seem to be using them for DC battery charging.

Some of my system specs:

PMA - single phase 2 wire, 100watts at 3000rpm
Bridge Rectifier (30 amp, full wave)
DC to DC converter, takes 0-30v (input is 20-30v) and produces a solid 12v
12v Samlex Pure Sine 100w inverter
 
you are trying to take too much power out. you need to generate more power ore take less out. for low power producers most people will just use a grid tie inverter that plugs into a wall socket and are content that some power they use is coming from their generator
 
That's a good call on the amount of power, I realize that. But even after losing 15% to the inverter and 15% to the DC/DC converter, from a PMA rated at 100w shouldn't I be able to power a 15w incandescent bulb? Seems like I am producing way less than 100w to begin with, which is puzzling.

Has anyone powered an inverter (with a regulator or converter inbwteen) directly from a PMA before?
 
HI Disco.

Get yourself a 1 (one) HP induction motor 1725 or 3450 rpm (120 volt).

Spin the motor/s At about 1800 or 3600 Flash it with 12 volts to start it, "If needed" This will return 120 volts at 60 cycles. You can trim the speed to get it to exacly 60 hz. One hp = 746 watts. You can run most things. "EXECPT" another motor.

Motors take to much power to start them. and will execeed the output, and cancel out the generator. You can Add caps. to stablize it. "Thats Highly Recomended".

S. Simon
 
You need either a large capacitor or battery at the input to your inverter. I'd recomend a lead-acid battery and up your dc-dc output to 13.2 v.
 
Looks like the problem is not so much power, but DC "ripple". When you rectify AC current to DC, even with a full wave bridge, your still producing pulsating DC voltage and current. The challenge becomes "smoothing" that power to a constant DC. I am fooling around with a couple of capacitors but so far no luck.

There are a few circuits explained on the web for DC ripple filters, but I have yet to find a company that has a black box that can eliminate ripple. Anyone know of an off the shelf solution? I know most power supplies (ac to dc) have them built in, but it's hard to find the correct volt/amp combo I need.
 
The simplest one is to just use a big enough capacitor.

Thats it no complicated circuits just a big enough capacitor or set of capacitors.
 
Are you sure it is single phase? A PMA with internal 3 phase full wave rectifiers mounted in case has two wires out (case and one wire for DC out). It is unusual to have a single phase PMA.

Generator-inverters like Honda and Yamaha models have 3 phase PMA, full wave rectified feeding a DC-AC sinewave inverter. Their PMA produce high voltage DC (with full wave rectified, three phase ripple). The inverter just PWM's the high voltage DC. They have L-C filter to A.C. output. Output is very clean sinewave.

https://www.hydrogenappliances.com/powerpmas.html

These guys use an automobile alternator housing for their PMA's.
 
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That link to the hydrogenappliances PMA seems like a pure case of a scam, take a look at the magnet rotor they show- neo magnets... They also say it gets real hot but state 325 amps output from very thin wire. At 80C neo magnets start to degrade, at 150C they are DEAD. For the money they are selling them for one would be better off just making a dual axial flux genny and make the coils to suit the application.

To the original OP trying to use a car alternator pma to power an inverter WITHOUT a batterbank is asking the inverter to let the magic smoke out....
 
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