Re: EV Grin Returns

[Rich Rudman <rmanzan@tscnet.com>]

Lee Hart wrote:
> 
> Rod.Hower@ametek.com wrote:
> > The problem with the Curtis was not just efficiency (which I can only
> > guess is only 2% or so better on the DCP).
> 
> The efficiency of a PWM controller is tricky to measure. If you measure
> just the controller itself, it will be in the high 90's. But, the ripple
> current it causes in the batteries and motor cause additional losses.
> Though these are hard to measure and thus usually ignored, they are
> actually larger than controller losses. My guess would be 2% loss in the
> controller itself, and another 2-5% loss each in the motor and
> controller.
> --
> Lee A. Hart                Ring the bells that still can ring
> 814 8th Ave. N.            Forget your perfect offering
> Sartell, MN 56377 USA      There is a crack in everything
> leeahart_at_earthlink.net  That's how the light gets in - Leonard Cohen
I did a heat budget once for the Raptor 1200s, it's like 98.875 at Full
power, The losses scale with amps.
It's really amazing to beable to controll 180,000 watts of power and
have only 2.2 Kw of losses.
Yes Lee that's a simplicifaction.  14 Fets at 0.022 Ohms at 1200 amps.
There are diode losses but they occur only when the Fets are off. Then
switching losses and resistive losses in all the conductors. But still
that not more than 2.5 Kw at full 1200 amps of scream.

Rich Rudman