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Date: Mon, 28 Apr 2008 22:00:39 -0400
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: the Kubota dynamo
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George Lendich wrote:
> Scott,
> So that's what a regulator does, I though it regulated current flow to 
> the battery, maintaining 12 to 14 volts.
>
> Our 'Ship Chief' must be into electronics, now let me get this 
> straight- you must have a switching regulator, which consists of a 
> regulator with a solid state circuit, which switches current on and 
> off - off when the current exceeds a certain limit ( voltage?) and 
> back on at other times.
>
> I will get used to this electronics stuff eventually - just tell me if 
> I interpreted this incorrectly! At lest I will know what to ask for.
>
> On a similar matter I'm seriously looking at a motorbike style 
> generator/ alternator. The one on my Suzuki would be up to the task as 
> it put out sufficient power for an 1800 cc, fuel injected Twin 
> cylinder - just have to work out how to attach it to the motor.
> George ( down under)
I have one of the Harley generators.  It's rated for 30A.  The magnets 
are mounted to the inside edge of a heavy gauge cake pan...heavy gauge 
being defined as something like 0.100".  This will bolt up to my 
flywheel, with the bottom of the pan against the flywheel.  It will spin 
at 6000RPM in cruise, which is right about where it would spin on a 
motorcycle.

The stator looks like an octopus that has been tied up with copper wire 
for some sort of medieval torture.  It's got two wires coming off of it 
that go directly to the regulator.  The stator will bolt directly to the 
back of my PSRU.  The wires don't spin, or move at all for that matter 
(relative to the mounting points).  No contacts.  No slip rings.

Voltage is a driving force.  Current is what is being driven.  The 
switching type regulator takes advantage of the fact that when you first 
apply a force, it takes a while for the driven stuff to start moving.  
We're talking microseconds, but there is a delay.  When the rotor spins 
to fast, you get to much of a driving force.  If left unchecked, the 
ship's systems will be overloaded.  Before this can happen, the 
regulator turns the generator off.  Without a circuit, no current flows 
and there's no load on the generator*...because it has nothing to push.  
Before the current runs out (and the voltage drops as a result), the 
regulator switches the generator back on.  The regulator does it fast 
enough so that nobody notices the ripple of voltage going up and down.

I'm counting on this for my design of replacing the distributor with a 
small generator.  I'll set the regulator at 11V.  Ships power will be at 
least 12V.  Because it will always see the ship as being in overvoltage 
during normal operation, it won't actually switch on.  If I have a power 
outage from the main generator, the distributor mounted generator will 
kick in, and (through a diode arrangement) drive the primary electronic 
ignition.

That should create enough controversy to keep Ed going  8*)

-- 

http://www.ronpaultimeline.com