The constant increase in the cost of electricity makes many people think about the need to organize an independent system of their own energy supply. In addition, sometimes this is the only way to provide adequate quality electricity. The search for solutions to the problem of self-supply with voltage leads to the need to understand how the generator is made.
Although now there are quite a few revolutionary solutions that allow you to get electricity from almost nothing, they do not find practical application, being not always efficient, giving way to the time-tested option with an electric motor.
Prerequisites for creating a generating device
To learn how to make an electricity generator, one should remember the basics of electrical science. In the section on motors, it is clearly stated that any of them can work not only as a consumer, converting the work of the charge into the mechanical energy of the shaft rotation, but also in the opposite mode, converting the mechanical moment into the potential at the terminals. This feature is called the lawreversibility of electrical machines. Actually, this is the basis of how the generator is made.
Engines
When choosing an electric motor, you should know that they can be direct or alternating current. Since when considering how the generator is made, most often they mean exactly the “change”, then we will not talk about “permanent”. AC machines exist in variations with a phase and squirrel-cage rotor. In the first case, the ends of the windings are led to a special device with a set of contact pads, which are powered by graphite "brushes". Using such solutions as a generator is more difficult.
Working principle
To understand how the generator is made, you need to imagine the processes that occur in the engine during operation. Consider a three-phase model. When power is applied to the terminals of the stator winding (fixed part), a magnetic field arises in it, the lines of intensity of which cross the closed rotor winding (a rotating "drum"). Due to this, a current is induced in the latter, which generates its own magnetic field. The interaction of these two fields creates a torque. It's that simple.
Consequently, based on the law of reversibility, it is necessary to spin the rotor by external influence, and remove voltage from the stator windings. In generators sold in retail chains, the torque is created by a gasoline engine. Although the efficiency of such a system is low, it works.
Severalnuances
People who have already studied how a generator is made know that there are a number of features of connected circuits. By unwinding the shaft and connecting the load to the terminals, it will not be possible to fully unlock the potential of the device. The reason for this lies in the fact that no current occurs in the turns of the rotor winding (the magnetization is small and fades away). To solve this problem, an effective solution is used: a block of capacitors connected in a triangle is placed between the three terminals of the three-phase motor under consideration. That is, a wire is connected to each corner from the terminal of the stator winding, and three outputs to the load also depart from here. Capacitors of a non-electrolytic type, such as MBGT, MBGO, etc., must be used. Their voltage must be at least 600 V. The capacity depends on the load (the more powerful it is, the higher the class of capacitors) and engine characteristics. For example, for a 2 kVA generator, the battery capacity is at least 28 microfarads.
It is not recommended to use the generator without load due to the resulting heating. You also need to take into account that for a three-phase electric motor, from which 220 V is removed in generator mode, the power will be one third of the nameplate.
Shaft rotation speed must be at least synchronous. Otherwise, a reduction in frequency and/or voltage is observed.
Most often people have a question: "How to make a wind generator?" Everything is logical: the wind is a free resource that is always available. This solution includes: engine; blades on the shaft, tuned to a certain angle; block of capacitors. If initially planned to producelow voltage, an additional inverter and battery are required.
