Generic reference
http://en.wikipedia.org/wiki/AC_motor
PWM is just one type of motor controller which has lots of issues. Actually there are multiphase dc only brushless motors using pwm drivers and they leave brushed versions of motors for dead.
Yours,
Andrew Gilchrist
fastelectrics.com
Australia
0419 429 201
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of Roger L
Sent: Thursday, 18 April 2013 10:37 PM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Orest have u considered AC motors
Uh-oh....If I may join the conversation..... it looks like I may have to go back to school on electric motors. It's a Good Thing that learning something new is always fun.
The only electric motors I am familiar with are the high efficiency kind made with permanent magnets and driven by a pulsed DC wave. And without really thinking about it, I've been making the assumption that this was the type used in electric boats.
But if so, why is AC any different from pulsed DC? In that type of motor I don't know of any reason or advantage to sinusoidally reverse the polarity of the driving wave. (making it AC).
Am I missing something?
thanks,
Roger L.
.........
..............
----- Original Message -----
From: Andrew Gilchrist
Sent: Wednesday, April 17, 2013 8:18 PM
Subject: [Electric Boats] Orest have u considered AC motors
Orest
there is another option – others here my have tried it
You may want to look at an AC motor . A DC motor’s amp draw and torque level fall away at higher rpm, an AC motor has a lower start torque – but you don’t really need much at low rpm, but the high end torque is better.
If that isn’t an option a more efficient better sized prop than the current one could achieve very significant gains either in performance or efficiency
Yours,
Andrew Gilchrist
fastelectrics.com
Australia
0419 429 201
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