T-Pain Is On A Boat: Re: [Electric Boats] Drive train noise

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