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Re: (ET) On an entirely different topic
There's also other issues with series vs shunt wound motors....
DC motor torque is main field flux and armature current.
Series motors are good when you want simple control, no separate
power supply for the main field. A large (armature current sized)
contactor has to reverse the series field for reverse direction - there
is no field weakening to make the motor run faster than base speed.
Big advantage is simple control with rugged components and very high
torque at low speed and less torque at battery voltage but for forklifts
and such, a good system.
Shunt motors use many turns of small wire with separate power supply
to reverse polarity for direction and apply field strengthening or
weakening to provide higher speeds and more versatility - encoders are
commonly used with today's drives for precise speed control.
For Elec-traks, I think the tractor is much better suited for a shunt
wound control system with the manual transmission.
...Walt
-----Original Message-----
From: Jim Coate [mailto:jbc_lists_NO_REPLY coate org]
Sent: Saturday, February 26, 2011 11:15 AM
To: Elec-Trak
Subject: Re: (ET) On an entirely different topic
When comparing your costs, keep in mind that most PM set-ups will
require a high current reversing contactor, which can be spendy. There
are some PM controllers (half- or full -bridge configuration?) that
provide electronic reversing, but at additional cost.
Geof Thompson wrote:
> I am just wondering, given the cost controlers and the cost of motors
> to-day, is there and advantage to the SepX motors over PM motor, give
> that pulse controler for PM motors are fairly in expensive and have a
> full range of speed control.
> Geof Thompson
>
>
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--
Jim Coate
*The Electric Tractor Store*
http://www.ElectricTractorStore.com
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