An asynchronous generator is an asynchronous electric motor operating in generator mode. The drive motor rotates the rotor of an asynchronous electric generator in the direction of the magnetic field, thereby causing a negative slip of the rotor, the occurrence of a braking torque and the flow of electrical energy into the network.
Why are asynchronous generators good?
Asynchronous generators have the following advantages over synchronous ones:
- A simpler device compared to synchronous, for example, car generators.
- If synchronous ones have induction coils on the rotor, then the rotors of asynchronous generators look like ordinary flywheels.
- Such generators are better protected from moisture and dirt.
- More resistant to short circuits, overloads.
- The output voltage of an asynchronous generator has a lower degree of non-linear distortion.
Video on how to make an electric generator from an asynchronous motor
All these advantages make it possible to use asynchronous generators not only as power sources for various industrial devices, but also for powering electronic equipment. It is asynchronous generators that are ideal current sources for devices with an active (ohmic) load – these are electric heaters, and welding converters, and incandescent lamps, and electronic devices, computer and radio engineering. This raises the question: is it possible to make an asynchronous motor with your own hands?
Generator from asynchronous electric motor
An asynchronous electric motor does not have a magnet on the rotor, and in its place there are short-circuited turns. Therefore, at first glance it may seem that making a generator out of it is an impossible task. However, using capacitors for this purpose, such an idea can still be realized. Moreover, making a generator from an asynchronous motor is quite simple.
Connect a voltmeter to any of the three windings of the induction motor.
Then the motor shaft should be untwisted, as a result of which it will be possible to see indicators on the voltmeter indicating the presence of a voltage that has appeared. Where did it come from if the rotor is without a magnet? The fact is that the voltage appears as a result of the residual magnetization of the rotor. Of course, due to the small magnetization, the voltage will also be correspondingly small, much less than the rated supply voltage of the motor.
It cannot yet be called a generator, but what will happen if you try to create a magnetic field with the help of short-circuited turns of the rotor? Since, when using the engine for its intended purpose, the short-circuited turns of the rotor receive current and are magnetized from the alternating magnetic field of the stator windings, the same effect can be obtained when the engine is running in generator mode.
Further, in order to make a generator from an asynchronous motor with your own hands, you need to bypass one stator winding with a capacitor. In this case, the capacitor must be chosen not electrolytic.
Then the shaft should be untwisted, as a result of which a small voltage will first be generated on the stator winding, and after a while it will begin to increase and become equal to the rated voltage of the electric motor.
The best result can be achieved with equal values of the resonant frequency of the oscillatory circuit and the frequency of the generated voltage, which depends on the shaft speed. When the shaft rotates at a frequency close to the nominal for the motor, the frequency indicators of the generated voltage will also be close to the nominal. Then shunt the remaining windings on the motor with a capacitor and connect them.
Do-it-yourself wind generator from an asynchronous motor
A wind generator from an asynchronous motor is easy to do with your own hands. In addition, it does not require significant costs for its manufacture. Very often, home-made designs of a wind generator of electricity are made exactly according to this principle, using an asynchronous motor.
Video on how to make a wind generator from an asynchronous motor with your own hands
Homemade power plant from a walk-behind tractor
Many craftsmen generate electricity using a walk-behind tractor, which is usually used to plow and clean gardens. To implement this idea, an asynchronous electric motor (for example, the AIR series) used as a generator is required. How to make a generator from an induction motor is described in the following instructions:
The ratio of generator power and capacitor capacity:
An active load is sometimes possible with a single capacitor. To use all three phases to power a single-phase tool, a three-phase transformer is used. If during operation the generator becomes very hot, then the capacitance of the capacitors decreases. The operating voltage of the capacitors must be at least 400 V.
Video on how to make a generator from an induction motor
If you know how to make an electric generator out of an asynchronous motor, then with the help of such power plants you can also heat the house. But for this you will need to use a more powerful gasoline engine.