Thanks for the scoop, James.
If I didn't already have a $450 MillipaK, It'd be easier to pay out $595 for the new Gen4. But that will have to wait.
PS: At idle, the MillipaK draws a lot less than 750A. :)
-Tom
--- In electricboats@yahoogroups.com, James Lambden <james@...> wrote:
>
>
>
> There are about 100 variables to characterizing a controller for a
> certain motor.
>
> I was present when the Sevcon Engineers characterized the Gen 4 for
> the Mars 20 turn, 28 turn, and double stator 28 turn motors.
>
> They run the motor on an oscilloscope, spin the motor as a generator
> to find out its voltage to rpm constant, and input other variables
> from the electrical design of the motor.
>
> There are error control loops for past, present and future operation,
> each weighted differently. Change one variable too far the wrong
> way and the motor will not perform, or act like a speaker, or hickup,
> or vibrate.
>
> I characterized the Gen 4 for the double stator motor myself, and had
> it running fairly well, but notice dramatic improvements when
> Sevcon's engineers did the characterization process. Its a very
> difficult task and requires specialized training, not to mention the
> software to make the changes. And then the program is tested on a
> motor hooked up to a dyno.
>
> The Millipak consumes 750 amps in its idle state and reaches peak
> efficiency at full power. And its peak efficiency at 5 KW is
> probably less than 80%.
>
> The Gen 4 controller solved all of the problems of the Millipak.
> They put millions of dollars into the research and development of the
> Gen 4 over a period of 10 years. The Gen 4 makes is efficient over
> the entire rpm of the motor. With an electric sailboat you want
> your efficiency at low power levels which makes motor sailing
> possible and with great range.
>
> The Gen 4 is an expensive controller, but worth every penny.
>
> And it runs all of the Mars motors quietly.
>
> James
>
>
>
>
>
>
>
>
>
>
> On Nov 9, 2010, at 6:40 PM, Tom wrote:
>
> >
> >
> > --- In electricboats@yahoogroups.com, Rick Campos <rick_1211@>
> > wrote:
> > >
> > > Adjusting the pmac controller correctly ( as James Lamden stated
> > previously) will reduce the noise to a mere bee buzz.
> >
> > Hi Rick and James,
> >
> > I'm all for adjusting the controller to reduce the noise level.
> > But what specifically would need to be adjusted on a Sevcon
> > Millipak to minimize noise when running the MARS PMAC motor? Which
> > parameter(s) is/are likely to be the issue? Has anybody made a
> > significant noise reduction this way?
> >
> > -Tom
> >
> >
>
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