Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous Motor

[David Sharpe <sparktron01@xxxxxxxxx>]

Stefan

Excellent work!  Could you sketch up a little more detailed
description of the diode addition and commutator modifications
necessary to make this work?

In the US, these motors are used in vacuum cleaners, particularly
"Shop-Vac" wet dry type units; and in exercise treadmills.

Also below is a primer from GE Digital Energy on Synchronous
Motors (think >100HP / 100kW), with additional information on
starting, and abnormal operation.  Since this motor is a unique
hybrid between a Universal / Synchronous Motor, this background
information may be quite useful.

http://www.gedigitalenergy.com/products/manuals/spm/spmman-a9.pdf

Synchronous Motor background information is in Section 3.
Disclaimer:  I am not advocating use of GE products, although
I have installed this controller at one clients site, and it has
been in operation for 2 years 24/7/365 with no return calls.  There
are other manufacturers (Basler Electric, SEL, Siemens, ABB)
that can provide similar products.

Best Regards and Happy Holidays

On Fri, Dec 17, 2010 at 10:45 AM, Teslalabor <teslalabor@xxxxxxxxxxx> wrote:
> Hi,
>
> I think today I was able to make a vast improvement. The key is, not only
> soldering 2 segments, there have to be soldered at least 2 segments on each
> side together.
>
> After soldering 2 segments on each side, the "crazy-mode" completely
> disappeared, as you can see in this video, and the motor becomes
> selfstarting:
>
> http://www.youtube.com/watch?v=n0uJiIwhpq8
>
> Then I soldered another segment on each side and the motor gets more current
> and therefore more power and the sync gets much more stable, I think the
> more segments, the heavier the load the motor can accelerate:
>
> http://www.youtube.com/watch?v=nAK5eAKoZHk
>
> And then, with 4 segments on each side, the motor runs quiet perfect:
>
> http://www.youtube.com/watch?v=iNyOuBh9vaA
>
> It is self-starting from every starting position the armature has. And, I
> recognized, that it is important to apply voltage to motor fairly abruptly,
> as David Sharpe said, not with a variac.
>
> So, I think even more segments could be soldered but then it will be
> necessary to reduce the current with additional resistors in series with the
> diodes. There will be a "sweet spot" of the optimal amount of segments but I
> am to lazy to find it out ;-)
>
> Best Regards
> Stefan
>
> ----- Original Message ----- From: "Clive Penfold"
> <clivepenfold@xxxxxxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Friday, December 17, 2010 2:48 PM
> Subject: Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous
> Motor
>
>
> Hi,
>
> My motor is self starting. The point of the diodes is to make a 2 pole
> magnet on
> the rotor, so they will not only carry the mains current, they will also
> carry
> what I would call flywheel current that keeps that part of the rotor
> magnetised.
>
> The next thing I want to try is moving the diodes round spanning less
> segments
> so they don't form a short circuit across the brushes.
>
> A friend of mine makes some interesting observations on another discussion
> group
> here:
>
> http://www.electrokinetica.org/forum/viewtopic.php?f=3&t=244
>
>
> Clive
>
>
> ________________________________
> From: Teslalabor <teslalabor@xxxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Sent: Friday, 17 December, 2010 8:29:53
> Subject: Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous
> Motor
>
> Hi Gary,
>
> what I can say is, that the diodes become very hot. I have soldered two
> diodes each 6A in parallel so the current through the diodes I think is more
> than 12A. Heavy currents are induced when rotating and of course, when the 2
> shorted segments are passing the brushes, it's like a short circuit in the
> diodes with only the stator coils in place. Maybe this is the reason they
> get so hot.
>
> In my opinion it would even be possible to add some resistors, in series
> with the diodes?! I think the "poles" in the armature are to strong with
> only the diodes. I have some commercial sync motors here (arround 80W each)
> and they have a normal armature like every induction motor and only 2 weak
> permanent magnets on each side of the short-circuit armature. This is enough
> to "force" the armature in sync. So I think it might help to put resistors
> in series with the diodes and keep the poles much weaker.
>
> Stefan
>
> ----- Original Message ----- From: "Gary Lau" <glau1024@xxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Friday, December 17, 2010 4:22 AM
> Subject: Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous
> Motor
>
>
>> Hi Stefan,
>>
>> Interesting - thank you for doing and posting this.
>>
>> Here's my uneducated guess - let me see if any of this makes sense?
>>
>> It was stated that it was necessary to Variac the mains voltage down
>> considerably to achieve proper operation.  Could it be that when the motor
>> was operating in nice synchronous mode, that the applied voltage is
>> roughly
>> what would result in 3000 RPM operation of an un-modified motor?  And that
>> the motor REALLY doesn't like having those diodes in the circuit at
>> anything
>> other than a synchronous 3000 RPM with the diodes aligning with the
>> brushes
>> at the mains zero crossing.  So if the RPM is more than 3000, the diodes
>> start some high-current bucking, resulting in the RPM edging back down to
>> 3000 to achieve no current through the diodes?  I wonder if replacing the
>> diodes with wires would operate any differently???  It appears that the
>> applied voltage is very critical, and if it's off very much from a
>> sweet-spot, it will torture the motor with crazy-mode.
>>
>> Regards, Gary Lau
>> MA, USA
>>
>> On Thu, Dec 16, 2010 at 3:38 PM, Teslalabor <teslalabor@xxxxxxxxxxx>
>> wrote:
>>
>>> Hello,
>>>
>>> today I modified a 400W universal motor from a washing machine. I used 2
>>> diodes each 1kV/6A. I did a scope test which shows that the motor runs
>>> perfectly sync:
>>>
>>> http://www.youtube.com/watch?v=yOlfzxzucy8
>>>
>>> But there are 2 problems: The motor is not self-starting AND the motor
>>> sometimes runs in "crazy mode", as I call this strange behaviour.
>>> "normal-mode" and "crazy-mode" - both can be seen in the video.
>>>
>>> Best Regards
>>> Stefan
>>>
>>>
>>> ----- Original Message ----- From: "Clive Penfold" <
>>> clivepenfold@xxxxxxxxxxxxxx>
>>>
>>> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
>>> Sent: Tuesday, December 07, 2010 6:46 PM
>>> Subject: Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous
>>> Motor
>>>
>>>
>>> Phil,
>>>
>>> Yes, that is correct. Brief explanation along with some photos here:
>>>
>>> http://4hv.org/e107_plugins/forum/forum_viewtopic.php?102515.last
>>>
>>> Regards,
>>>
>>> Clive
>>>
>>>
>>>
>>>
>>> ________________________________
>>> From: Phil Tuck <phil@xxxxxxxxxxx>
>>> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
>>> Sent: Tuesday, 7 December, 2010 15:10:17
>>> Subject: RE: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous
>>> Motor
>>>
>>> DWP,
>>> I think there is some misunderstanding here. I don't think the sensor and
>>> magnet
>>> were triggering the strobe as you do (I think that is what you're
>>> thinking?)
>>> The presumption is that the magnet was attached to the motor shaft such
>>> that it
>>> passed and induced a voltage into a fixed coil once per rev.
>>> If so, the output will always coincide with the electrode passing that
>>> point in
>>> space.
>>>
>>> If the scope is setup to show both channels overlaid, and the output from
>>> the
>>> sensor coil is fed into one channel, with the mains fed in on the other
>>> channel,
>>> and the output from the sensor subsequently always coincides with the
>>> same
>>> point
>>> on the mains sine wave, then the motor is synchronous.
>>>
>>>
>>> I use an infra-red sensor being tripped by the electrodes and it work
>>> fine.
>>>
>>> Regards
>>> Phil
>>>
>>> www.hvtesla.com
>>>
>>> -----Original Message-----
>>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
>>> Behalf
>>> Of
>>> dave pierson
>>> Sent: 07 December 2010 12:34
>>> To: Tesla Coil Mailing List
>>> Subject: Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous
>>> Motor
>>>
>>>  The poster mentions that he had "the mains on the other" [ channel] So
>>>>
>>>> I assume a mains reference sine wave on the other channel.
>>>>
>>>    Good point.  However:
>>>
>>>  In usual engineering use of the term synchronous motor, the speed is
>>>>>
>>>>> set by the line frequency.  Strobe Testing with a magnet spun by the
>>>>> same motor as a sync source demonstrates that one end of the motor
>>>>> (where the magnet is) is 'synchronous' with the other end.
>>>>>
>>>>
>>>  If a scope is to hand: most have a 'line sync' position, which syncs
>>>>>
>>>>> the scope to the _line_ freq.  With line sync selected, a reading
>>>>> from the flying magnet to a sense coil would be interesting.
>>>>>
>>>>
>>>  A motor which (happens?) to be running at 3000 (ish) will appear
>>>>>
>>>>> synchronous to 50 (or 60, or 30 or 100).  A proper synchronous motor
>>>>> will hold synch Under Varying Load.
>>>>>
>>>>   The key is just above.  a 'truly synchronous' motor will
>>>
>>>   hold speed, and phase, under varying load and input
>>>   voltage, (within reason...).
>>>
>>>   best
>>>    dwp
>>> _______________________________________________
>>> Tesla mailing list
>>> Tesla@xxxxxxxxxx
>>> http://www.pupman.com/mailman/listinfo/tesla
>>>
>>> _______________________________________________
>>> Tesla mailing list
>>> Tesla@xxxxxxxxxx
>>> http://www.pupman.com/mailman/listinfo/tesla
>>>
>>> _______________________________________________
>>> Tesla mailing list
>>> Tesla@xxxxxxxxxx
>>> http://www.pupman.com/mailman/listinfo/tesla
>>> _______________________________________________
>>> Tesla mailing list
>>> Tesla@xxxxxxxxxx
>>> http://www.pupman.com/mailman/listinfo/tesla
>>>
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxx
>> http://www.pupman.com/mailman/listinfo/tesla
>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>



-- 
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA

Sharpe's Axiom of Murphy's Law
"Physics trumps opinion!"
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla