Are rotor coils separate for AC and DC in a rotary converter?

Discussion in 'General Electronics Chat' started by AidanCroft, May 4, 2015.

  1. AidanCroft

    Thread Starter New Member

    Jan 7, 2015
    24
    2
    Hello all,

    If I understand it correctly, to convert single phase AC to DC using a rotary converter, AC is supplied to the rotor coils in a permanent field via slip rings causing the rotor to spin - like a conventional AC motor.

    Then, this rotation causes electrically separate rotor coils to have a current induced in them as they are rotating in a permanent field, causing DC to be output via the commutator.

    If this correct?

    Are the rotor coils for the AC and DC sides indeed electrically separate?

    Kind regards,

    Aidan.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,524
    2,369
    Typically they are two systems on a common shaft, the AC motor one end and the DC the other.
    The AC end is fed to the stator coils. If the rotor on the AC side has slip rings it would be for rpm control.
    Max.
     
  3. AidanCroft

    Thread Starter New Member

    Jan 7, 2015
    24
    2
    I don't quite understand this wording:

    "The rotary converter can be thought of as a motor-generator, where the two machines share a single rotating armature and set of field coils. The basic construction of the rotary converter consists of a DC generator (dynamo) with a set of slip rings tapped into its rotor windings at evenly spaced intervals. When a dynamo is spun the electric currents in its rotor windings alternate as it rotates in the magnetic field of the stationary field windings. This alternating current is rectified by means of a commutator which allows DC current to be extracted from the rotor. This principle is taken advantage of by energizing the same rotor windings with AC power which causes the machine to act as a synchronous AC motor. The rotation of the energized coils excites the stationary field windings producing part of the DC current. The other part is AC current from the slip rings which is directly rectified into DC by the commutator. This makes the rotary converter a hybrid dynamo and mechanical rectifier. When used in this way it is referred to as a synchronous rotary converter or simply a synchronous converter. The AC slip rings also allow the machine to act as an alternator. The device can be reversed and DC applied to the field and commutator windings to spin the machine and produce AC power. When operated as a DC to AC machine it is referred to as an inverted rotary converter".

    Aidan.
     
  4. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    There are several types of systems like you describe. You may want to do a Google of "amplidyne" for some interesting results. Additionally a Google of "Motor Generator" will bring up some additional interesting results. Both focus on a motor, generally an AC motor with a common shaft driving an AC or DC generator. They can be in a sense a mechanical amplifier where a small signal (excitation or field windings) can result in a very large signal out (rotor windings). While these devices were for the most part heavy duty bullet proof brutes they are slowly going the way of the dinosaur being replaced with newer solid state devices like IGBT Inverters. I worked quite a few tears with large GE Amplidynes and Kato Motor Generators and there were only a few still in use when I retired as they were phased out. Pretty cool stuff in their day. Dynamotors were another cool device of their time.

    Ron
     
  5. AidanCroft

    Thread Starter New Member

    Jan 7, 2015
    24
    2
    Research seems to imply that the AC and DC components of a rotary converter share the same armature windings. How does this stand against what members here know?

    Aidan.
     
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