Generator from an asynchronous motor with your own hands. How to convert an asynchronous motor into a generator

Make a generator of an asynchronous motor with your own hands is easy, but you will have to try and spend some money for the purchase of components. But for the work you need to know some subtleties. In particular, the principles of the AC induction motor , to study the basic elements of its design. The main thing in generator sets is the motion of the magnetic field. It can be provided by rotating the armature using an internal combustion engine or a wind turbine. It is also possible to use alternative sources - water, steam, etc.

Design of an asynchronous motor

You can select only a few elements:

1. Stator with winding.
2. Front and rear covers with installed bearings.
3. Rotor with shorted turns.
4. Contacts for connection to the electrical network.

If you think about it, it may seem that it is very easy to remodel the engine into a generator, a photo of which you can examine in detail. But if you look more carefully, it turns out that not everything is so simple, there are plenty of pitfalls.

The stator consists of a set of metal plates pressed tightly to each other. Also they are varnished, in some designs, to give strength, all the plates are welded to each other. The wire is wound on the stator, it fits snugly against the core and is isolated from it by means of cardboard inserts. In the caps there are bearings, with their help not only easier rotation of the rotor, but also its centering.

The principle of the engine

The essence of the whole process is that a magnetic field is formed around the stator winding. It is quite powerful, but lacks the main component - the movement. The field is static, motionless, and the main condition in generator sets is rotation, changing the direction of the lines of force. In the case of the engine, everything is quite simple - there is a rotor, which is made of metal. Inside, several turns of very thick cable. And all the turns are closed, connected with each other.

It turns out the principle of a simple transformer. In short-circuited turns, EMF is induced, which creates an alternating magnetic field in the surrounding space. It turns out that now everything is in order for the movement to appear. Under the influence of forces, the rotor of the electric motor rotates. This type of machine has good characteristics, and the design is simple and reliable, there is nothing to break. For this reason, asynchronous motors are widely used in industry. More than 95% of all motors in factories and factories are asynchronous. It is possible to manufacture a generator with own hands, the circuit of which is not very complicated, everyone can, with minimal knowledge.

Connection to a single-phase network

The true problem is the connection of an electric motor, designed for three phases, to one. The principle of the generator is slightly different, but for its understanding it is necessary to consider the motor process. It is necessary to use a capacitance that will allow you to make a phase shift in the desired direction. And there are several schemes used in practice. In some, the capacitor is only used at the time of launch, in others and at work. The starting capacity is switched on for a short period of time, until the necessary speed is reached. It contacts it through a switch in parallel with one of the windings connected by a triangle circuit.

These connection options have one significant drawback - reducing the power of the electric motor. You can get from him as a maximum of 50 percent return. Therefore, at a motor power of 1.5 kW, in case of power from a single-phase network, you can only get half-0.75 kW. This imposes a certain inconvenience, as it is necessary to use more powerful electric motors.

How to get three phases from one

For more convenient use of electric asynchronous motors, it is necessary to supply power from three phases. But not everyone can bring such a network to their homes, and there are also difficulties with taking electricity into account. Therefore it is necessary to get out, as it turns out. The easiest way to install a frequency converter. But its cost is high, not everyone can allocate such a sum for their own garage or workshop. Therefore it is necessary to use improvised means. You will need an asynchronous motor, a capacitor and an autotransformer. As the last one, you can use a homemade device made of a motor core. You can even make a generator drawing to simplify the assembly work.

On it it is required to wind about 400 turns of a wire. Its diameter is about 6 square meters. Mm. For accuracy, it is required to make ten taps to complete the phase adjustment. It can even be said that it is a generator of an asynchronous motor, made by oneself. Only its main function is the transformation, the phase shift. One winding is connected to the phase, and between the two the capacitor is connected. The second winding is connected to zero, the third is connected there, only through the autotransformer. Its average output is one phase, the other two are the outlet sockets.

What to consider for rework in the generator

To make a wind generator from an (asynchronous!) Engine, you will need to consider one main feature. Namely - to create a magnetic field that will move. There are two ways to achieve this. The first is the installation of permanent magnets on the rotor. The second is to make the winding of the excitation at anchor. Both methods have both advantages and disadvantages.

You need to decide before starting the work, the current generator of what kind you need. If you need a constant, then you need to use diodes for straightening. This will provide a light for a small house, as well as supply almost any household equipment. Homemade current generators can be driven even by wind power. It is only necessary to calculate the windings, so that the output does not exceed the voltage. Although stabilization can be done with the use of regulators used in automotive engineering.

Constant magnets or excitation winding?

As mentioned earlier, it is possible to make a field winding or to mount permanent magnets. The drawback of the latter method is the high cost of magnets. A minus the first is the need to use a brush assembly to provide power. He needs care and timely replacement. The reason is friction, which gradually consumes the surface of the graphite brush. Any car generator, the instruction to which is necessarily attached, has this disadvantage.

To make the excitation winding, it is enough to change the design of the armature. It must be metal, it must be wound with a wire in varnish insulation. Also, it is required to establish contacts at one end of the rotor, which serve for feeding. But the plus is that it is possible to stabilize the voltage at the generator output. It will be easier to make grooves at the anchor for mounting niodim magnets. They create a very strong field, which is enough to generate large values of voltage and current.

How many phases do you need at the output?

The simplest way is, of course, to make a generator whose photo is shown if there is only one phase to be output. But here there is a snag - not every design allows you to do this. A homemade generator from an asynchronous motor of this type can be made if all windings are withdrawn and not connected to each other. Many motor models have only three outputs, the others are already connected internally, so to realize the idea you need to completely disassemble it and pull out the necessary wires outwards.

Then they are connected in series and the output can receive a single-phase voltage. But if you need a three-phase, you should not do anything, you do not need to upgrade the windings. But it is still necessary to take into account the features. It is necessary that the generator of an asynchronous motor, made with its own hands, has a winding connection according to the star scheme. Here is a slight difference from the variant, when the machine works as a source of motion. Effective generation of electricity is possible only when the star is switched on.

How do I rectify the current?

But if there is a need for a direct current, you need knowledge of circuitry. Do you need 12 or 24 Volt voltage? There is nothing easier, automotive electronics will come to the rescue. But only if the excitation winding is used as a magnetic field generator. When using permanent magnets, the stabilization procedure becomes more complicated.

The rectifier option is chosen based on the number of phases at the output of the generator. If one, then quite enough bridge circuit, or even on a single diode (half-wave rectifier). If there are three phases at the output, then there will be a need to use six semiconductors for rectification. Also three pieces (one for each phase) - to protect against reverse voltage.

How to make three of a single phase

This action is not necessary, because it is simply meaningless. Generator if gives three-phase alternating voltage, then to power the consumers (TV, incandescent lamp, refrigerator, etc.), it is necessary to use only one terminal. The second is the common, the point of connection of the windings. As it was said earlier, it is required to connect them according to the star scheme.

Therefore, you have the opportunity to connect consumers to one of the phases. The question is, is there any sense, is it rational to do this? If you want to provide the house with light only, do not plan to connect any consumers, then it's more reasonable to use low-power LED lights. They consume a small amount of electricity, so the current generator, which produces a stable 12 volts, is able to provide the house with not only light. You can easily include and household appliances, which requires this kind of voltage to work.

Rules for winding wires

This information is not always necessary, since, in order to simplify the design, the stator winding that is already available is used. But it does not always satisfy the conditions that face you. For example, if you construct a wind generator from an (asynchronous) motor, you can not obtain the minimum rotor speed. Consequently, the output voltage will be small and insufficient for the operation of household appliances. Therefore, there is a need for small modifications.

The winding should be carried out with a thicker wire in order to obtain a higher value of the current strength at the output. To do this, get rid of the old wire. Winding is carried out closely, on a cardboard frame. When it is carried out, it is required to apply a layer of varnish, it is necessary to impregnate the wire abundantly with it. Just do not forget to dry it well before operating the device. To do this, a 25 or 40 W incandescent lamp is installed in the middle of the stator and leave for 1-2 days. Do not leave it unattended.

Experimental determination of the required number of turns

To determine how many turns you need for the normal operation of the generator, you need to use a variety of formulas. But you need to know the cross section of the core, the material from which it is made. But it is often impossible to determine. Therefore, we have to do experiments. Depending on whether you need one or three phases, the algorithm for conducting the experiment changes. A homemade generator from an asynchronous motor can be manufactured by various methods.

If you plan to make one phase at the output, then wind evenly around the core of 10-20 turns of wire. Assemble the entire structure and connect to the drive, which will be used in the future. Measure the voltage at the output, divide by the number of turns that are wound. And you get the voltage removed from one turn. To calculate the length of the winding, you need to apply a simple calculation - the voltage (necessary) divided by the value obtained. Similarly, a three-phase generator is also calculated .

conclusions

Make a generator of an asynchronous motor with your own hands is easy. The most important thing is to decide which drive you plan to use. If this is a conventional gasoline engine, then there will be no problems. Great difficulties will arise if you use a windmill as a drive. The reason - engine speed, as well as output voltage, directly depend on the strength of the wind, its speed. Therefore, such generators must be calculated in such a way that even at minimum rpm the rated voltage is generated . But at the output it is desirable to have no more than 12 volts. This will be a simpler solution.