Re: (ET) Curtis controller mod - Field - Buck converter maybe

["David Roden" <etpost drmm net>]

On 30 Apr 2016 at 10:27, Briggs, Michael wrote:

> Off-hand, I can't think of any other losses that would be introduced due 
> to
> weakening the field. The main downside is that you have less torque.

The interesting thing about FW is that once you're into it, motor power 
output becomes constant.  That is, as the speed increases at full field, 
power output also increases; but when you go into FW the power curve 
flattens. This is because in FW the torque goes down as the speed goes up.

Since torque is what mkes acceleration possible, the vehicle will speed 
up, 
but more gradually.  At some point you reach equilibrium, where the torque 
isn't sufficient to overcome losses for further acceleration, and that's 
your top speed.  Do I have that right?  


David Roden - Akron, Ohio, USA

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