Hilden-Brand Magnet Motor

[JRHall]

I think a thread for a standard test plan would be good. 

So far we've talked about functionally validating a technology at nominal conditions.  i.e. 25C ambient temp.  That will validate the technology is viable but will not show how it works under real world conditions.  Most of this technology will be run under extended environmental conditions.  So once intial testing is completed at nominal then testing over temperature, humidy, vibration and thermal shock will help determine if there are anamolies.  Highly Excelerated Life Testing or Halt does a very good job of determining operating limites and weak points in a design. 

I've seen a lot of designs that work great at 25C but fail to function at 0C or 45C.

[mark australia]

Liberty, I am having trouble sending you emails..they all bounced to day.
Please email me with an alternative address at mark.dansie@advatel.biz
thanks

[Liberty]

Liberty, I am having trouble sending you emails..they all bounced to day.
Please email me with an alternative address at mark.dansie@advatel.biz
thanks

Sorry about that, the ISP that I use had a server crash of some sort.  I think that they nearly have it put back together now.  I noticed the web site is back up.  It may work again if you want to try it again.  I will email you with an alternate email just in case.

Liberty

[z_p_e]

Hi Jack.

Would you be able to disclose the gauge of wire you are using with your N48 magnets? Also, if you go up or down in magnet size, does the wire gauge remain the same?

I would guess that as the magnet size goes up, so does the wire guage (bigger wire). This would allow you to increase the number of turns and/or the wire length, without increasing the final coil resistance.

z_p_e

[jake]

The "reactance" of the coil could be much more of an issue than the resistance, especially when you are applying a pulsed waveform to the coil.  "Reactance" could be described as the AC resistance of the coil, and it changes (increases) with the applied frequency.

If you want to drive the coil at a high frequency, I would determine the ampere-turns required by building the coil with a reasonable wire size (Jack noted that he is driving at .08a, 100v, I think - any reasonable sized wire will handle that).  Test the coil and adjust the current until you get the desired result under static conditions.  Measure the current.  Multiply the measured current in amps times the number of turns on the coil.  This gives you the ampere-turns necessary to get the proper magnetic flux. (Any number of turns with the correct current can be used to create that amount of flux)  At this point you know the magnetic requirement of the coil.  Now you must decide what frequency you are going to drive the coil at, and bulid a coil optimized for that frequency, which involves a number of calculations to tune the coil to the desired frequency.

The problem with not tuning the coil to the operating frequency is you can't get the current moving in the coil rapidly enough.  Performance will suffer because by the time you produce the flux the rotor may have passed you by.

The problem with driving coils with square waves (pulses) is that the harmonic frequencies in square waves are very high, even if the fundamental frequency is low.  Any coil has a relatively high resistance to square waves, which tends to knock the corners off the waveform.  You may have to severly overdrive the coil to get the desired current throuth it when pulsing it, especially with short duration pulses.

My gut feeling is that you might be better with larger wire, less turns, more current, less voltage.  Your copper losses might be a little higher, but you will be able to drive at higher frequencies because of the decreased reactance of the coil.  Jack is using 8w coils at 100v.  You can get the same result with 50v, 25v, etc, by increasing the current and decreasing the turns.  I think a pulse (square) waveform will work better with fewer turns on the coil.