Turning a single phase motor into a generator

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Discussion Overview

The discussion centers around the feasibility of converting a single-phase induction motor, specifically a washing machine motor, into a generator. Participants explore various methods and considerations related to this conversion, including the use of capacitors and the characteristics of induction motors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant identifies the motor as a single-phase induction motor and explains that it has two field windings, suggesting that a series capacitor can create a rotating magnetic field to operate the motor.
  • Another participant mentions that it is generally easier to convert a three-phase induction motor into a generator compared to a single-phase motor, detailing the use of three AC capacitors and the importance of mechanical speed for generating electrical energy.
  • Some participants assert that an induction motor can function as an induction generator without modification, although there is uncertainty about whether it needs to be spun up first or can operate standalone.
  • A suggestion is made to replace the washing machine motor with a front-loading washing machine motor, which is noted to have a three-phase permanent magnet configuration that can generate AC power effectively.

Areas of Agreement / Disagreement

Participants express differing views on the practicality of converting a single-phase induction motor into a generator, with some suggesting it is feasible while others indicate it is more challenging compared to three-phase motors. The discussion remains unresolved regarding the specific methods and effectiveness of the conversion.

Contextual Notes

There are limitations regarding the assumptions about the motor's capabilities, the need for modifications, and the conditions under which it can operate as a generator. The discussion does not resolve these uncertainties.

william04
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Hi I’m a year 12 student and I’m trying to turn a washing machine motor into a generator. In my physics class we have only learned about AC generators using permanent magnets but the motor I’ve got doesn’t have any magnets and I believe that it is called an induction motor? Anyway I’m still eager to try and turn it into a generator but I’m struggling with how it could be done. I want to leave drilling holes in the squirrel cage to attach magnets as a last resort. I have found people online talking about how you can use a capacitor bank to start the circuit but I don’t know how this would be done. I’ve attached photos of what I have at hand and if anyone could explain how I would be able to turn it into a generator would be much appreciated.
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Welcome to PF.

That is a single-phase induction motor. It has two field windings that share a common wire, and have physical fields at 90°. By feeding one through a series capacitor, the current is phase shifted, which results in a rotating magnetic field, that drags the rotor around.

It is hard to make a single-phase induction motor into an alternator. It is much easier to make a self excited alternator from a three-phase induction motor. Usually three AC capacitors are connected in a triangle, then connected to the three wires of the 3PH motor. When you mechanically spin the motor above a fixed speed, it begins to generate 3PH electrical energy. That speed, and the frequency of the voltage it generates, is set by resonance of the motor winding inductance and the external capacitance.

https://en.wikipedia.org/wiki/Induction_generator
 
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anorlunda said:
You should be able to use an induction motor as an induction generator.. I believe without modification.

https://en.wikipedia.org/wiki/Induction_generator
Interesting... I had no idea they could be used standalone - I always thought they had to be spun up first and then connected to an already running grid. Also nice to know they can start up from their residual magnetism.
 
Scrap the washing machiene and replace it with a front loading washing machiene motor. Mine had a 3 phase perminant magner motor that will run as a 3 phase AC generator and put out a fair amount of current.

A 3 phase bridge transformes it to DC
 

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