----- Original Message -----From: EricSent: Wednesday, September 08, 2010 8:34 PMSubject: Re: [Electric Boats] Mars PMAC and Kelly ControllerDoug,
You should try to find out if the Mars PMAC is optimized for BLDC or A/C vector control. Here's some info about the differences:
"Although BLDC motors are practically identical to permanent magnet AC motors, the controller implementation is what makes them DC. While AC motors feed sinusoidal current simultaneously to each of the legs (with an equal phase distribution), DC controllers only approximate this by feeding full positive and negative current to two of the legs at a time. The major advantage of this is that both the logic controllers and battery power sources also operate on DC, such as in computers and electric cars. In addition, the approximated sine wave leaves one leg undriven at all times, allowing for back-EMF-based sensorless feedback.
Vector drives are DC controllers that take the extra step of converting back to AC for the motor; they are sophisticated inverters. The DC-to-AC conversion circuitry is usually expensive and less efficient, but these have the advantage of being able to run smoothly at very low speeds or completely stop (and provide torque) in a position not directly aligned with a pole. Motors used with a vector drive are typically called AC motors. When running at low speeds and under load, they don't cool themselves significantly; temperature rise has to be allowed for.
A motor can be optimized for AC (i.e. vector control) or it can be optimized for DC (i.e. block commutation). A motor which is optimized for block commutation will typically generate trapezoidal EMF. One can easily observe the shape of the EMF by connecting the motor wires (at least two of them) to an oscilloscope and then hand-cranking/spinning the shaft."
While either type of controller should work with each type of motor, matching them correctly should result in a more efficient drive line. Most of the controllers that I have researched in our power range are BLDC controllers.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "Doug" <dj2210@...> wrote:
>
> Dan
> I don't believe that Alltrax makes a controller that will work with the Mars brushless PMAC motor.
>
> --- In electricboats@yahoogroups.com, Daniel Michaels <nov32394@> wrote:
> >
> > I have no experience with any of the controllers but I have heard good things about the Alltrax controller.
> >
> > Dan
> >
> > --- On Wed, 9/8/10, Doug <dj2210@> wrote:
> >
> > From: Doug <dj2210@>
> > Subject: [Electric Boats] Mars PMAC and Kelly Controller
> > To: electricboats@yahoogroups.com
> > Date: Wednesday, September 8, 2010, 3:08 PM
> >
> > Just an update to my conversion and a question. I already have the motor, speed reducer and various components for my Catalina 27 but have yet decided on a controller. Has anyone used the Kelly controller (KBL48xxx) with the MARS PMAC (PMSM) yet in their project? How is it working out?
> >
> > Thanks
> >
>
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