T-Pain Is On A Boat: Re: [Electric Boats] Electric drive noises

Thursday, March 10, 2011

Re: [Electric Boats] Electric drive noises

Tom,

I haven't heard anything from the Gen4 controller. As far as I can tell, it is truly silent. My experience with DC controllers in EVs is that some will "whine" at certain settings, I think that it's some sort of harmonic related to PWM or something like that. That noise comes from the controller itself. There may be other mechanical harmonics that show up as motor noise. They may be related to motor mount plates or other physical pieces. These will occur when a minor vibration falls in synch with a piece's natural resonance (like your tires on certain sections of highway) and each pulse is perfectly timed to push the resonance farther, making any noise louder. Usually, a slight change in system speed will break the cycle. The other option is to add a flexible mount or pad to de-couple the vibration source from the "sound board" component.

On my boat, the low-speed growl (very noticable) is the only noise that I didn't expect. I knew that the motor wouldn't be silent, the noise during normal operation is reasonable to me. Once I get the whole installation (wiring, additional components, etc.) locked down, I may try to mitigate some of the mechanical noise that I get today.

Fair winds,
Eric

--- In electricboats@yahoogroups.com, "Tom" <boat_works@...> wrote:
>
> Eric wrote:
> "If I slow the motor below 200 rpm, it seems to run less smooth. I think that the permanent magnets of the Mars motor start "stepping" at very slow speeds. Has anyone else noticed anything similar with the Mars PMAC motor? I'm running a Gen4 controller."
>
> Hi Eric,
> I running the same motor with the Sevcon Millipak PMAC controller.
> I get a definite "growl" at very low RPMs. As you suggested, I suspect it has to do with the cogging of the PM rotor.
>
> In addition I have a pronounced "singing" or "ringing" at some speeds.
>
> James mentioned that the Gen4 controllers, when properly configured, were a better match for the MARS PMAC motor with regard to noise. I had considered swapping out my controller for a quieter version, but now I'm not so sure. Does your installation have a similar singing or ringing noise? I have known of other MARS PMAC/Sevcon Milliak installations that had the same noise issues I am experiencing.
> Sound insulation has helped, but it is still irritating.
>
> -Tom
>