Isn't "Wide Band Noise" what RF guys overcome every day? The reason you tune a radio is to ignore the 50 million otherchannels and the sun/jupiter/everyelectronicdevice known to man and concentrate on your own.. I can use my cell phone in my EV just fine. If noise was really insurmountable, then I wouldn't be able to do that.
Seems to me that with enough selectivity over enough time, you can ignore every bit of noise known to man. As I said the Ham guys can pick out signal in signal to noise ratios of -120db. That's 12 orders of magnitude and they can detecta walkie/talkie on the other side of the globe. It's amazing. Sure it's only a few bits/min, but the point is that it IS doable. It requires a different mindset than just straight digital manipulation. You accept error rates and deal with them using math. On Tuesday, April 28, 2020, 9:58:47 PM PDT, Offgrid Systems via EV <ev@lists.evdl.org> wrote: Yeah I'm gonna agree with Lee here. I've been thinking about this for years also, going as far as testing some ac powerline comm chips adapted to DC power busses. I found it's impossible with all the noise coming from the drive on an EV. But Lee, you don't even need a spectrum analyser, just fire up your EV drive train, looking at any of the phases with a oscilloscope. It's wide band noise, and the motor control is modulating to operate the motor, but with sinewave drives, or even the old PWM drives, there is noise during the entire cycle, and the only way you get a quiet time is if you actually shut off and short the motor for a brief period. But if you do that there will be high peak currents that will not be good for the efficiency of the drive. If reliability is the key, you will not want to use the DC busses, unless it's a low noise application, and you can control and build all of the power devices, like maybe a powerwall with a pure sinewave inverter, and you make the charger (solar charge controller) and the inverter. But for motor control, it's a difficult problem to solve. Tim Economu On 4/28/2020 6:48 PM, ev-requ...@lists.evdl.org wrote: > It sounds easy; but put a spectrum analyzer on your battery leads to see > what's*really* there. I think you'd be shocked at the noise level. > >> There are a few clever tricks you can employ. During charging, you can >> have the charger pause for a regular "moment of silence" in which the >> BMS can communicate quickly and in the clear without having to "shout" >> over the charger PWM. Perhaps the same thing could occur to a lesser >> extent with the inverter. > Same as above. Are you going to design a special charger that must be > used with your BMS? > > There are lots of solutions that work*some* of the time. There are a > few that work*most* of the time. But it gets damnably difficult to find > schemes that work*all* of the time. > > The problem is that a BMS is a safety system that you want to work*all* > of the time. > > Lee Hart -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200428/80bb080d/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200429/71df7f62/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
