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

[dave pierson <dave_p@xxxxxxxxxxx>]

> A vacuum cleaner motor can be made to run at synchronous speed with
> the addition of a diode; actually 2 in parallel for mechanical balance
    There is a deal of difference between running at 3,000 rpm
    and running synchronously.

> Mains vacuum cleaner motors are usually series wound AC brush motors.
> The one I removed from a 1100 watt Miele cleaner ran at 18,000 rpm and
> drew 5 amps at 240 volts.

> Having dismantled it, I soldered two 3 amp 1000 volt diodes across  2
> opposite commutator segments (180 deg apart),  tucked down behind the
> commutator.
    A circuit drawing would help.  Slowing a motor form 18,000 to
    3,000 is by half wave rectifying is a deal different than
    synchronous operation.

> One would have done but to maintain physical balance, I used a pair
>  opposite each other and applied a liberal amount of epoxy resin to
> stop  them flapping about.
 
> The motor is still series connected as before and runs at 3000 rpm (at
> 50 Hz) quite happily from 30 volts AC where it draws 0.8 amp to 80 volts
> AC where it draws 5 amps at no load.

> One  thing that I haven't looked at yet is the phase change of the
> rotor as the load varies but it is probably no worse than an
> induction motor with flats machined on it.
   An induction motor is quasi synchronous in any case, with
   a better lock with the flats.  A series commutator motor
   is inherently controlled by voltage/current.

best
 dwp
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