How can a car dynamo display create electricity? Dynamo flashlight from a stepper motor. Tail light circuit with dynamo

An electrical energy generator is a device that converts chemical, mechanical or thermal energy into electricity. Such a generator, used on bicycles to power the rear lights and headlights, is Dynamo machine .

Varieties

Let's consider existing species factory-made bicycle dynamos.

Bottle shop

This type of bicycle generator is the most affordable and simple. However, its power is not the greatest of all types. The generator drive roller rotates by touching the tire tread while driving.

Bush Dynamo

The hub dynamo is an axial dynamo in its design. Executions of such models can be various types. The cost of a bushing generator is quite high. Installation is more complicated compared to the bottle version.

When purchasing, you must check the number of spokes and the method of fixing the installation wheel. The advantages of a bushing generator include its protection from moisture, unlike a bottle generator, the drive roller of which slips over the bicycle tire in wet weather. The device is enclosed inside the wheel hub, and the work comes from its rotation.

The disadvantages of such a device include the fact that it is not possible to turn off the operation of the bushing generator.

Chain

The chain version of a bicycle generator is quite rare. However, there are several different versions of this type. The device can be equipped USB port for charging mobile gadgets.

The disadvantage of this design is its short service life, since during operation the metal bicycle chain impacts the plastic elements of the generator.

Contactless

This is an original dynamo with a non-contact operating principle. The bicycle wheel plays the role of a rotor. A special hoop with 28 magnets is attached to the wheel. They are arranged alternately, with different poles.

The stator is an induction coil in which electric current is generated. This system includes accumulator battery for energy storage. According to the manufacturer, to ensure normal light flux, it is enough to move at a speed of 15 km per hour.

The advantages of this design are:

• No rubbing elements.
• Quiet operation.
• Unlimited service life (except for batteries).

The disadvantage of the contactless model is the low battery capacity. It only lasts a few minutes. However, many craftsmen easily correct this deficiency. different ways, including replacing the battery with a more powerful one.

Other designs

Currently, various interesting devices that are made in China are very popular. Sometimes you see devices that have never been produced anywhere before. Even their operating principle is not always clear, but they work.

This Chinese device can easily be called the bicycle generator of the future. The dynamo from heaven looks similar to science fiction films. Judging by its appearance, it does not require contact with the wheel bar or chain to function. There are also no magnets.

The principle of its operation is not entirely clear. Perhaps this is a technological secret of the manufacturer.

Design features and operation

The most popular dynamo design on bicycles is the bottle design, followed by the hub dynamo. Other types are used much less frequently. Therefore, we will consider the most common models.

Dynamo bottle

The bottle-type dynamo runs on the side of the front tire of a bicycle. It is made in the form of a small generator of electrical energy, and is used to operate the rear light and front headlight of a bicycle, as well as charge electronic mobile devices.

Such a mini-generator can be mounted on both the front and rear wheels. In the first case, the device can be combined with a built-in flashlight. To turn off the generator, a special folding mechanism is provided, which fixes the generator housing in a position where there is no contact with the bicycle wheel tire.

The name of this device comes from the external resemblance of the shape to a bottle. The bottle generator also has another name – side dynamo. The drive rubber or metal roller is driven into rotation on the side of the wheel tire. When the bicycle moves, the tire imparts rotational motion to the bicycle generator roller, which generates an electric current.

Advantages

• The disconnected generator drive offers no resistance the movement of the bicycle. When the generator is turned on, the cyclist has to apply more force to move. A hub dynamo, unlike a bottle bicycle generator, always resists wheel rotation, although the value of this resistance is insignificant. If the bottle generator is turned on, but the lights and headlight are not connected to power, then the resistance to the movement of the bicycle is less.
• Lightweight and easy installation . Such a device is easy to install on any bicycle, unlike a hub generator, the installation of which requires the assembly of the entire dynamo wheel with spokes.
• Low cost . These models usually cost less than other types of bicycle generators, although there are exceptions to this rule.

Flaws

• Complex setup . Careful adjustment and adjustment of the wheel's contact with the tire at a certain angle, tire pressure, and height is required. If the bike is dropped or the retaining screws become loose, the alternator may be damaged. An incorrectly adjusted generator device will make a lot of noise, create excessive resistance, and slip on the wheel. If the fastening screws are too loose, the mechanism may move out of place and get caught in the wheel spokes, which will lead to broken spokes and failure of the bicycle wheel. Some bicycle generators are equipped with special loops that prevent them from getting into the spokes.
• Requires physical effort to switch . To activate the generator, it is necessary to move its housing until it comes into contact with the wheel. Bushing generators can be switched on automatically or electronically. You don't need to put any effort into this.
• Increased noise . During operation, a humming noise is heard, while hub dynamos do not create noise.
• Wheel tire wear . To operate the generator, contact with the tire is required, resulting in friction and tire wear. If you compare it with a dynamo hub, there is no friction with the tire.
• Motion resistance . A bottle dynamo offers significantly more resistance to the bike's movement than a hub model. However, when correct setting The resistance is insignificant, and when switched off it is absent.
• Slippage. In wet, rainy weather, the drive roller of the bottle generator will slide on the tire tire, which reduces the generation of electric current and reduces the brightness of the headlight and taillight. Hub generators do not require good tire grip to operate and are not affected by weather or other adverse conditions.

Dynamo hub

The hub design of the bicycle generator was developed in England and produced by various companies in many countries. The power of this design can reach 3 watts at a voltage of 6 volts. Their manufacturing technologies are constantly being improved, the dimensions of the structure are becoming smaller and more powerful. Modern bicycle headlights begin to emit more efficient light, as they are used.

Hub dynamos do not create noise during operation, but their mass is greater than that of other models. There are no rubbing parts in the sleeve version of the device. They operate due to a magnet having many poles and made in the form of a ring. It is located in the bushing body and rotates around a stationary armature with a coil fixed on the axis. The rotational resistance of this design is very low.

Hub dynamos produce alternating current. At low speeds, more electricity is generated compared to the bottle model due to the low frequency of the current. There are rectifier circuits for a dynamo. They are made using a simple bridge circuit of four diodes.

The hub dynamo produces low voltage, therefore, when using silicon diodes, the losses are significant - 1.4 volts. With germanium diodes, losses are reduced and amount to only 0.4 volts.

Working principle of a dynamo

A dynamo produces electric current using the effect of electromagnetic induction. The rotor rotates in a magnetic field, resulting in an electric current in the winding. The ends of the rotor winding are connected to a collector made in the form of rings. Through them, with the help of pressing brushes, electric current enters the network.

The current in the winding has a maximum value if the rotor is perpendicular to the magnetic lines. The greater the angle of rotation of the winding, the less current. Rotation of the winding in a magnetic field changes the direction of the current twice in one revolution. Therefore, the current is called alternating.

A similar generator for direct current manufactured on the same principle. The difference is in some details. The ends of the winding are connected not to rings, but to half rings, which are isolated from each other. When the winding rotates, the brush contacts each half ring in turn. Therefore, the current flowing to the brushes will have only one direction and will be constant.

Now a lot of digital equipment is breaking down, computers, printers, scanners. Time is like this - the old is replaced by the new. But equipment that has failed can still serve, although not all of it, but certain parts of it for sure.
For example, stepper motors of various sizes and powers are used in printers and scanners. The fact is that they can work not only as motors, but also as current generators. In fact, this is already a four-phase current generator. And if you apply even a small torque to the engine, a significantly higher voltage will appear at the output, which is quite enough to charge low-power batteries.
I propose to make a mechanical dynamo flashlight from a stepper motor of a printer or scanner.

Making a flashlight

The first thing you need to do is find a suitable stepper motor small sizes. Although, if you want to make a flashlight larger and more powerful, take a large engine.

Next I need a body. I took it ready. You can take soap dishes, or even glue the case yourself.

We make a hole for the stepper motor.

We install and try on the stepper motor.

From an old flashlight we take the front panel with reflectors and LEDs. Of course, you can do all this yourself.

We cut out a groove for the headlight.

We install a luminary from an old flashlight.

We make a cutout for the button and install it in the groove.

In the free area we place the board on which the electronic components will be placed.

Flashlight electronics

Scheme

In order for LEDs to shine, they need constant current. The generator produces alternating current, so a four-phase rectifier is needed that will collect current from all motor windings and concentrate it in one circuit.

Next, the resulting current will charge the batteries, which will store the resulting current. In principle, you can do without batteries - using a powerful capacitor, but then the glow will only appear at the moment the generator is turned.
Although there is another alternative - to use an ionistor, it will take considerable time to charge it.
We assemble the board according to the diagram.

All parts of the flashlight are ready for assembly.

Lantern dynamo assembly

We attach the board with self-tapping screws.

We install the stepper motor and solder its wires to the board.

We connect the wires to the switch and headlight.

Here is the almost assembled lantern with all the parts.

Channel Igor Kruch presented to your attention a new homemade product, which the author of the video made a long time ago, but all the time he could not film it and post it on YouTube. Finally a homemade big dynamo. The creation, which took about a month of work, was leisurely, thought out, everything was done with high quality, conscientiously.

Check out the selection of hand generators and neodymium magnets at this Chinese store.
It is made from what was available: an engine, a belt and a tensioner from inkjet printer. In addition: a toggle switch, a lithium-ion battery 18650. A stiffening rib has been added. A pulley is made from disks. At idle, it produces a voltage of up to 11 volts and a current of 1.5 Amperes. Enough power for led lights, low-power amplifier, smartphone. For a laptop, this homemade dynamo is not enough.
So, review. The wall and bottom are made of laminate, the remainder is left over after the renovation. The belt pulley is made of optical disks, unnecessary, as you can see, they were drilled and twisted. The belt is large, long, yellow color, from the old printer, just like the tensioner from the old printer, it was larger. I sawed off the unnecessary part.
The generator remained the same, the handle was also curved, this is necessary so that it does not cling to the belt and tensioner. It was curved, and the position of this handle changed, it was more convenient. In this case, the optimal gear ratio is achieved. Also new is a stiffening rib, because the laminate walls turned out to be too high, and it began to sway a lot, thanks to it everything is secure and nothing wobbles.

Electronics of a homemade manual generator

It is worth saying the following. The generator, diode and capacitors remained exactly the same as in the previous dynamo. One toggle switch and a battery pack were also added. I added connectors accordingly so that a load could be connected to it, conveniently through the connectors. On the left is a piece of sawn-off motherboard laptop, faulty motherboard. We got 3 USB ports for connecting power. A little to the right is a homemade scarf, a breadboard with 5 pins. Accordingly, 5 energy consumers can be connected and 3 energy consumers can be connected to 3 USB ports.
As a result, in total, in parallel, 8 consumers can be powered simultaneously from this dynamo, but for now only 2 consumers are in operation, I’ll tell you about them soon. The toggle switch is located at the front, and this is what the dynamo looks like from below. Nothing special to look at: 4 rubber feet on Double-sided tape 2 screws from the stiffener are also glued.

Note. The screws with which the disks are twisted are with a countersunk head; There are transverse notches on the pulley (otherwise the belt would slip) and the “piece of iron” on which the pulley rotates is a core from an old speaker. The batteries are attached to metal plates with neodymium magnets, which, thanks to the nickel coating, conduct current perfectly. The metal plates themselves are from the transformer core. There is a thick lubricant between the pulley and the hardware, as well as between the pulley and the laminate.

I made this friction bike generator for my bike to power my flashlight and rear lights. I found the idea and a lot of information for this pedal generator project on the Internet.

I recently bought a bike to commute to work and around town, and decided that for safety reasons I needed a light. My front light was powered by 2 AA batteries and the back light was powered by 2 AAA batteries, the instructions said the front light would last 4 hours and the back light would last 20 hours in flashing mode.

Although these are good indicators, they still require some attention so that the batteries do not run out at the wrong time. I bought this bike for its simplicity, the single speed means I can just hop on and go, but constantly replacing batteries gets expensive and makes it difficult to use. By adding dynamism to the bike, I can recharge the batteries while I ride.

Step 1: Collecting spare parts

If you want to build a dynamo machine with your own hands, then you will need a few things. Here is their list:

Electronics:

1. 1x stepper motor - I got mine from an old printer
2. 8 diodes - I used a personal power unit used 1N4001
3. 1x Voltage Regulator – LM317T
4. 1x Development board with PCB
5. 2 resistors - 150 Ohm and 220 Ohm
6. 1x radiator
7. 1x Battery connector
8. Solid wire
9. Insulation tape

Mechanical parts:

• 1x Bike Reflector Holder - I removed this from the bike when I connected the lights.
• Aluminum corner blank, you will need a piece approximately 15 cm long
• Small nuts and bolts - I used printer screws and some other used parts
• Small rubber wheel - attaches to the stepper motor and rubs against the wheel as it rotates.

Tools:

• Dremel - It's not entirely necessary, but it makes your life a lot easier.
• Drills and bits
• File
• Screwdrivers, wrenches
• A breadboard for testing the circuit before you put everything on the bike.
• Multimeter

Step 2: Create a circuit

Show 10 more images

Let's make a diagram of a dynamo for a bicycle. It's a good idea to test everything before you solder everything together, so I first assembled the entire circuit on a breadboard without solder. I started with the motor connector and diodes. I unsoldered the connector from the printer's circuit board. Placing the diodes in this orientation changes the AC current coming from the motor to DC (rectifies it).

The stepper motor has two coils and you need to make sure that each coil is connected to the same set of diode banks. To find out which wires from the motor are connected to the same coil, you just need to check the contact between the wires. Two wires are connected to the first coil, and two to the second coil.

Once the circuit is assembled on a breadboard without solder, test it. My motor produced up to 30 volts during normal cycling. It's a 24V stepper motor, so its efficiency seems reasonable to me.

With the voltage regulator installed, the output voltage was 3.10 volts. Resistors control the output voltage, and I chose the 150 and 220 ohm options to produce 3.08 volts. Check out this LM317 voltage calculator to see how I calculated my numbers.

Now everything needs to be soldered on printed circuit board. To make neat connections, I used small gauge solder. It heats up faster and provides a better connection.

In the .Pdf file you will find how everything is connected on the PCB. The curved lines are the wires and the short black straight lines are where you need to solder the jumpers.

Files
Files

Step 3: Installing the Motor

The engine mount was made of an aluminum angle and a reflector bracket. To mount the engine, holes were drilled into the aluminum. One side of the corner was then cut out to make room for the wheel.

The wheel was attached by wrapping duct tape around the motor shaft until the connection was tight enough to push the wheel directly onto the duct tape. This method works well, but it needs to be improved in the future.

Once the motor and wheel were attached to the aluminum, I found a good spot on the frame to mount everything. I attached the blank to the seat tube. My bike's frame is 61cm, so the area where the generator is mounted is quite large compared to smaller bikes. Just find the best place on your bike to mount the alternator.

Once I found a suitable location, I made marks for the aluminum bracket with the reflector bracket installed so it could be cut to size. I then drilled holes in the bracket and aluminum and mounted the structure onto the bike.

I finished assembling the 12 volt bicycle generator by attaching the project box to an aluminum mount with two posts.

Step 4: Connecting the Wires

The bicycle dynamo is assembled, now all you need to do is just connect the wires to the light bulbs. I pushed the ends of the wires past the battery terminals to the headlight, then drilled a hole in the headlight housing to feed the wires through. The wires were then connected to the battery connector. You will also need to make holes in the project box for the wires.

Dynamo machine

or, for short, dynamo. - This is the name of a machine through which, when using mechanical work, an electric current is generated, and vice versa, when using an electric current that is excited by some source of electricity (a battery of galvanic cells or accumulators or another machine) and passes through this machine, it can mechanical work is performed. In the latter case, the D.-machine receives the name - "Electrical engine"(electric motor). Any dynamo can equally serve both to generate current and, equally, to set in motion various mechanisms, i.e., perform mechanical work. The small difference that is noticeable between a D-machine used as a current source and a D-machine used as an electric motor concerns only minor parts in the design of the machine. The action of D., as a current source, is based on the property of the so-called "magnetic field" that is, the space in which magnetic forces are detected, excite an electric current in a conductor when, by some extraneous force, this conductor is set in motion in this space in a certain direction. This property of the magnetic field was discovered by Michael Faraday in 1831 and was named by him current induction. The action of D., as a motor, is due to another property of the magnetic field. The magnetic field itself causes the movement of a conductor if an electric current is passed through that conductor, suitably placed in the floor. This property of the magnetic field was first especially carefully studied by Ampere.

Let us first dwell on the characteristics of the magnetic field and get acquainted with the law to which the phenomenon of current induction is subject. As already stated, a magnetic field is a space in which magnetic forces are found. A small magnet placed in any place in this space, under the influence of such forces acting on both of its poles, tends to position its axis (a line mentally drawn in the magnet from the south pole to the north) in a certain direction. If a magnet can change its position quite freely, then the direction that the axis of the magnet takes in a given place of the magnetic field represents the direction of the magnetic force acting in this place of the field to the north. magnet pole. Through experiment it is possible to find the direction of magnetic forces at different points of the magnetic field. If these forces have directions lying in horizontal planes, or if it is desirable to determine the direction of the projections of these forces on a horizontal plane, then it is quite sufficient to sprinkle iron filings on a sheet of cardboard located horizontally in the part of the field being studied. The sawdust is magnetized under the influence of magnetic forces acting in the field and is placed in the form of chains in the directions of these forces in the horizontal plane. Through experiment, it is possible to determine the magnitude of the magnetic force acting on a magnet located in a magnetic field, and knowing the degree of magnetization of the latter (its magnetic moment), it is possible to calculate the magnitude of the force that each unit of the amount of magnetism contained in the pole of this magnet experiences. The force acting on a unit of magnetism located at any point in the magnetic field is taken as a characteristic of the field at this point. This force is called voltage magnetic field at a given point. Let us assume that for a very large number of points in the magnetic field under study, both the directions of the magnetic forces acting on the north pole of the magnet and the magnitude of the field voltage are determined. In this case, it is possible to imagine being carried out in this field magnetic lines of force. Each of them represents a line along which the north pole of a magnet would move in a magnetic field if it were possible to separate this pole from the south, that is, if it were possible to have a single-pole magnet, or, otherwise, a magnetic field line has the same property that a tangent drawn at any point on this line coincides with the direction of the magnetic force experienced by the north. the pole of a magnet placed at this point. The number of imaginary lines of force in a magnetic field is completely arbitrary, but we can agree to draw them in a certain way. Let us mentally construct in each place of the magnetic field so many lines of force that the number of them, calculated (by proportionality) per unit (1 sq. cm) of surface intersecting these lines at right angles, will be equal to the magnetic field voltage in this place (it should be noted , that what has been said should be understood in a general, abstract sense, i.e. the number of lines piercing a unit of surface can be either an integer or a fraction). It is easy to see that this method of constructing lines of force in a magnetic field makes it possible to graphically characterize this field.

Let us assume that we have some kind of magnetic field and know the distribution of magnetic field lines in it. Experience and theory show that when a conductor moves in such a field Not in the direction of the lines of force, and so that the conductor seems to cut these lines with itself, a special phenomenon is obtained in the conductor: an electromotive (or electroexcitatory) force is formed in it, which can form an electric current. This phenomenon represents the induction of current discovered by Faraday. Based on various experiments, Faraday derived the law of induction, which was subsequently proven theoretically by Maxwell and fully confirmed by many precise experimental studies. The electromotive force of induction, which appears at any moment in time in each part of a conductor moving in a magnetic field, is proportional to the number of lines of force cut by this part of the conductor - number calculated (by proportionality) per unit of time. The direction of the induction current, which from this electromotive force can appear in the moving part of the conductor, is also quite definite. The following rule for this is quite easy to remember. Let us imagine ourselves floating in the direction of the lines of force with our face turned towards the movement of the conductor, - the electric current produced by induction in the part of the conductor in question will appear to flow from left to right.

Electromotive force of induction appearing in everything conductor, is expressed by the sum of electromotive forces arising in its individual parts. The terms in this sum can have positive or negative signs, depending on the direction in relation to the entire conductor of the current excited separately by each of these terms of the electromotive forces.

Let's imagine that there is some kind of horseshoe-shaped magnet or electromagnet. Let us attach special iron plates to the ends of this magnet, facing each other with concave cylindrical surfaces. Let us place a ring or hollow cylinder of iron inside between these pole pieces (see Fig. 1).

In the space between the pole surfaces of the magnet and the placed iron cylinder, the magnetic lines of force will appear as almost parallel straight lines directed from the ends of the magnet into the iron of the cylinder. In Fig. Figure 2 shows the actual distribution of iron filings in such a space, located, as mentioned above, along the lines of force.

Let us bring the iron cylinder into rotation about its axis. With such movement around its axis at any angle of rotation, the cylinder will be equally located in relation to the magnet, and therefore the movement of this cylinder will not affect the placement and shape of the magnetic force lines in the space between the pole surfaces of the magnet and the iron cylinder. Let an iron cylinder be wrapped with copper wire so that the individual turns of the wire do not touch each other and are equally spaced around the cylinder. Let the ends of the wire of such a ring winding be soldered together. Let's place such a cylinder (or ring) surrounded by wire between the pole surfaces of the magnet and force two copper springs to touch the winding wire in two places located in a plane perpendicular to the direction of the magnetic force lines (see Fig. 1). When such a cylinder is set into rotation about its own axis, in each revolution of the annular winding external part, i.e. the part of the wire located on the outer surface of the cylinder, will cut the lines of force imaginary in the space between the magnet and core windings In each such part of the winding, current induction will occur. Applying the above law of induction to this case, we come to the conclusion that in all revolutions of each half of the ring winding (between two springs), at any moment of time, induction develops an electromotive (electrical) force, generating a current in one direction. This direction, however, is opposite in both halves of the winding.

So, in both halves of the winding of a rotating cylinder, the electromotive forces appearing in individual revolutions add up to each other and send one by one direction of current into a conductor placed between two springs. In relation to this conductor, both halves of the winding of a rotating cylinder are likened to two galvanic cells or batteries (see Galvanic battery) connected to each other parallel.

Based on the above law of induction, it is easy to show that electromotive force, arising when an iron cylinder (or ring) covered with a ring winding rotates between the pole surfaces of a magnet and generates a current in a conductor that is placed between the springs pressing on the winding, increases with the number of revolutions of the cylinder per unit time, along with the number of revolutions of the wire in the winding, the length of the cylinder and the magnitude of the magnetic field voltage excited by the magnet in the space between the pole surfaces and the core of the winding, i.e. the iron cylinder (or ring).

The described device makes it possible to obtain an electric current due to the work that is expended on the rotation between the pole surfaces of a magnet wrapped in the specified way, an iron cylindrical. or annular core, and represents Gram's magnetoelectric machine. The work required to rotate such a wire-wrapped iron core varies with the resulting current. (When there is a current in the winding, there is a counteraction to the rotation of this winding due to the influence that the magnetic field has on the current-carrying conductors). Before Gram's machines, that is, before the use of a similar wrapped iron cylinder or ring between the pole surfaces of a magnet, there were already other magnetoelectric machines in which the electromotive force of induction was excited in the same way in special coils rotating near the ends of the magnet, made of wire wound on iron rods or bundles of iron wires. The first such magnetoelectric machine was built by Pixia in 1832. In this machine, the magnet itself rotated, while the coils remained motionless; namely, a steel horseshoe-shaped magnet with poles facing upward, rotated about a vertical axis passing midway between its two halves, two fixed coils were placed above the ends of the magnet. Based on the above law of induction, it can be seen that when a magnet moves under these coils, an electromotive force of induction must develop in each of them. But this electromotive force at any moment has directly opposite directions in both coils and, moreover, in one and the other coil does not remain constant during a full revolution of the magnet. In each coil it varies from zero to its greatest value when one end of the magnet, in its movement from a position immediately below the coil, passes to a position 90° distant from the first; it decreases to 0 again when that end fits the second coil and the other pole fits the coil in question. With further rotation of the magnet, i.e. during the second half of its rotation, the direction of the electromotive force of induction in both coils is exactly the opposite. The current resulting from such a machine in any conductor will not change its direction only in the case when a special device, the so-called switch, by means of which, at appropriate moments, the connection of the ends of the conductor with the ends of the wire of the coils is changed. But, with a constant direction, the current still remains continuously changing in strength. Such a machine therefore produces a current wavy, which is a great inconvenience in many cases. The very relative placement of the pole surfaces of the magnet and the coils in the Pixia machine does not meet the conditions for obtaining the greatest electromotive force of induction in a given coil with a given magnet. When placing coils above With the ends of the magnet, the number of lines of force cut by the wire of the coils is not the greatest, and therefore the greatest possible electromotive force is not obtained. This remark regarding Pixia's car applies to many others. magnetoelectric machines that were built later. Until 1870, none of the existing machines, even when using stronger magnets instead of steel electromagnets did not make it possible to obtain a current that varied little in strength. Only this year, thanks to Gram's use of the above-described iron cylinder (or ring), wrapped in wire and placed between the ends of an electromagnet, magnetized by the same current that develops in a rotating winding, an electromagnetoelectric machine, capable of delivering an almost completely direct current, first appeared. An iron, cylindrical or ring-shaped core surrounded by an annular wire winding, i.e. gram ring, is the invention that laid the foundation for all modern electrical engineering. Actually, the same ring winding on an iron ring, like Gram’s, was made back in 1865 by prof. Pacinotti in his little electric motor. But Pacinotti’s invention was not of a practical nature and attracted very little attention.

When using the Gram ring, a constant current that does not change in strength can be obtained in the machine circuit for the following reason. With a large number of turns of the wire in the ring, both half of this ring, enclosed between two springs or metal brushes, as shown schematically in Fig. 1, during rotation the rings maintain almost unchanged their position relative to the lines of force. During this rotation, there is a continuous cutting of the lines of force by parts of the turns of the ring winding, but at the same time, in relation to the general distribution of the lines of force, there is a continuous replacement of one turn by another: each turn takes the place previously belonging to the neighboring one. The electromotive force, which is present in the entire half of the ring, remains constant during a full revolution of the ring around its axis.

The Gram rings actually used in machines are constructed differently from those just described. Fig. 5 (on the table) shows how such rings are actually arranged. The iron core of the ring is prepared from thin iron wires coated on the surface with scale and, in addition, with a layer of varnish. The arrangement of the wires, as can be seen in the cross-section of the ring, is such that the cross-section of the core is perpendicular to the direction of these wires; in this section, individual wires are separated from each other by layers of scale and varnish, and therefore induction currents cannot form inside the mass of iron, the direction of which coincides with the planes of the diameter of the core (Foucault currents) and which produce a harmful effect on the operation of the machine. A ring winding of insulated copper wire is divided into separate parts (36 or more), which are however in metallic connection with each other so that all these individual parts of the winding together form a continuous, unbroken conductor. From each place where one part of the winding is connected to the next, a wire goes to a copper plate, indicated in the figure by the letter R. There are as many such plates as there are divisions in the ring winding. All plates are insulated from each other either with asbestos, or vulcanized fiber, or sometimes with strips of mica, and are arranged so that they form a hollow cylinder. This cylinder or collector, is placed on the same axis on which the Gram ring itself is fixed, and therefore rotates simultaneously with this ring. Two metal brushes are pressed onto the outer surface of the commutator in a manner similar to that shown schematically in Fig. 1. It is easy to see that the use of the described collector with two conductive brushes touching it makes it possible, when the ring rotates in a magnetic field, to obtain in the conductor between these brushes a similar current, little changing in strength, as will be the case in the case of direct contact of the brushes with the wires itself windings (in Siemens machines called "Ring D." brushes and touch the rods that form part of the winding of the ring itself).

During operation of the machine, the position of the places where the brushes touch the commutator should not coincide with a plane perpendicular to the line connecting the middles of the pole surfaces, as is schematically shown in Fig. 1. The reason for this is that the position of the brushes on the commutator must necessarily be in a plane close to perpendicular to the direction of the lines of force. Only under this condition will both halves of the ring winding be symmetrical relative to these lines and, in addition, only in this case will the electromotive force of induction not develop in those revolutions of the wire that are connected to the collector plates suitable for the brushes, as a result of which, when the brush moves with one plate to another, a spark will not form from the action of self-induction at these revolutions. The direction of the magnetic force lines changes during the operation of the machine. The current appearing in the ring winding itself excites a magnetic field, which is composed with a magnetic field from an electromagnet, as a result of which some change occurs in the direction of the lines of force. Rice. 2-bis. shows the arrangement of iron filings in the space between the pole surfaces and the ring core when current develops in the ring winding.

In addition to the change in the direction of the power lines, another circumstance, namely a certain delay in the development of the electromotive force of induction in the ring winding due to the phenomenon of self-induction in the latter, forces the brushes to touch the commutator at a certain angle to the plane making a right angle with the line that connects are the midpoints of the pole surfaces. The brushes have to be moved from this plane to a certain angle in the direction of the ring movement. The angle of such movement of the brushes changes along with the change in current strength in the ring. The person observing the operation of the machine turns the brushes, which for this purpose are mounted on a special lever rotating near the commutator, until the sparks between the brushes and the commutator plates almost completely stop. Incorrect position of the brushes causes damage (burning) of the commutator.

From the above law of induction it is clear that the electromotive force appearing in the Gram ring increases with the increase in the voltage of the magnetic field in which the ring rotates. It is quite difficult to obtain a very strong magnetic field when using steel horseshoe magnets. It is incomparably more profitable in this regard to use electromagnets. To excite the magnetization of these electromagnets, there is no need to use any external current source. The current developed in the machine itself can serve this purpose. In fact, in the softest iron, if only it has been subjected to magnetization, noticeable traces of magnetism always remain; but even without preliminary magnetization, iron shows signs of magnetism due to the effect that earthly magnetism has on it. And therefore, between the pole surfaces of the electromagnet and the core of the rotating winding, even in the absence of current in the coils of the electromagnet, there is still a magnetic field, albeit of a very weak voltage. When the winding is set in motion, induction is excited in it, which can generate the current needed to magnetize the electromagnets. In 1867, for the first time, Werner Siemens built a machine in which a magnetic field was generated by an electromagnet, cat. magnetized by the current generated by the machine itself. In such a self-exciting machine, the electric current arises directly from the mechanical work expended in driving the winding between the ends of the electromagnet. V. Siemens named a similar machine D.-electric. Currently a shorter name "Dynamo" applied to all machines that excite electric current during the rotation of their moving part, the same - whether their electromagnets are magnetized by the current appearing in the machine itself, or whether separate current sources are used for this.

There are three types of D. machines with self-excitation: D. with sequential excitation (conventional D.), D. with branched excitation (shunt-D.) and with mixed excitation (compound-D.). IN ordinary D., all current resulting in anchored cars (anchor, or fittings, is the part of the machine in which induction is excited, i.e., for example, a Gram ring or another type of winding with an iron core) passes through the coils of an electromagnet. Fig. 3 (on the table) shows a diagram of the design of such a machine. Commutator brush (A) connected to one end of the electromagnet coil wire. Other commutator brush (b) and the other end of the wire of the electromagnet coils are "Borns" D., i.e. the external parts of the circuit are connected to them. When the anchor R will be brought into rotation, then the weak current that appears in it in the first moments from the action of the magnetic field, which is created by the residual magnetism of the iron of the electromagnet, passing through the winding of the electromagnet, enhances the magnetization of the latter, as a result of which it also enhances the induction itself. At subsequent moments of time, a stronger current already passes through the electromagnet, from which the induction continues to increase. Thus, after a relatively short time, the magnetization of the electromagnet reaches a certain maximum value and the machine produces a current, the strength of which corresponds to the size of the machine and the resistance of the external part of the circuit located between its borns.

IN D.-machine with branched excitation (shunt dynamo) From the armature of the machine, only a relatively small part of the current is directed to the electromagnet. For this purpose, electromagnet coils are prepared from thin wire, but the number of turns of the wire in them is large. The ends of the electromagnet winding are connected to the commutator brushes, which at the same time represent the ends of the external circuit, i.e. the brushes are connected directly to the “borns” D. Fig. 4 shows a diagram of a shunt-dynamo device. In practice, such D. are more convenient than ordinary. With a change in the resistance of the external circuit, the strength of the current passing through this circuit and in ordinary D. at the same time through the winding of the electromagnet must change, as a result of which the electromotive force of induction developing in the armature of these machines must change very significantly. In D. with branched excitation, on the contrary, the change in induction depends to a lesser extent on the resistance of the external part of the circuit. As the resistance of the external part of the circuit increases, i.e., as the current received from the machine decreases, that part of the current that branches into the electromagnet increases, as follows from the law of current branching. The result of this may be complete compensation of the influence of an increase in the resistance of the external part of the circuit, and therefore a machine with very different resistances of external conductors (with a different number of incandescent light bulbs) can produce almost the same potential difference on its borns. However, with significant changes in the resistance of the external part of the circuit, in order to achieve complete constancy of the potential difference across the D. borns, it is necessary to adjust the machine. For this purpose, together with the winding of electromagnets, a special rheostat is inserted into the branch (shunt) of the dynamo (see Fig. 4). By changing the resistance of this rheostat, a similar adjustment is made.

IN compound dynamo constancy of the potential difference on the borns is achieved (or sometimes constancy strength current in the external part of the circuit - this is in the so-called D. with constant current) using two windings in an electromagnet. One winding is prepared from thick wire and connected to brushes as in conventional windings, that is, it is placed in a circuit in series with the armature; the other winding is made of thin wire and with a high number of turns. This winding is inserted into a branch "parallel" to the armature (Brösch system) or into a branch "parallel" to the outer part of the circuit (Thompson system). In both cases, appropriate resistance and speed of both electromagnet windings are required. Currently, compound dynamos are used relatively rarely. The most common shunt dynamo.

In addition to the Gram ring, reinforcement and other shapes are used in D-machines. An objection is raised against the Gram ring that in it a relatively small part of the winding directly perceives induction. In fact, in a Gram ring, only that part of the winding that is on the outer surface of the core cuts the power lines. To avoid this, the machines of Siemens, Edison and others use fittings first constructed by Werner Siemens. That's the name. fittings type "Siemens drum". Fig. 6 shows a method for winding wire around the core of such an armature. The core itself is a cylinder; made from circles of sheet iron separated from each other by sheets of paper and pressed tightly together. The winding is composed, as in the Gram ring, of several parts, and each part of the winding is attached to a collector plate.

In the machines of Schukkert, Mordey, Gulcher and others, an anchor is used in the form of a Gram ring, which has a large outer diameter and a large thickness along the radius, but a very short length along the axis. This is the so-called “flat ring” type anchor. There are fittings of other shapes: for example, in a Desrosier machine, the armature has the form of a disk made up of copper wires arranged in a special way, in the form of zigzags. This anchor has no iron core at all. There is a Fritsche machine, in which, on the contrary, the disk armature is made only of iron wires. In the Thomson and Houston machine, the armature has the shape of a ball and consists of 3 separate windings, making an angle of 120° with each other with the planes of their revolutions. The shape of electromagnets in different machines is also very diverse. Most simple form has an electromagnet in Siemens machines (type II). Fig. 8 (table) represents appearance such machines. Fig. 7 depicts the appearance of the oldest D. Gram. The electromagnet in it is like a connection identical the poles of two horseshoe-shaped electromagnets. An electromagnet in a D. type “Manchester” has a somewhat different appearance from this (Fig. 9). The Manchester machine is one of the most solidly and correctly constructed D-machines. Fig. 10 shows the design of Schukkert D-machines with flat reinforcement.

In the described D., the magnetic field in which the armature rotates is formed by two poles of one electromagnet. Nowadays, it is quite common to construct magnetic machines in which there are several electromagnets. Such D. are called “multipolar”. Such D. can be considered as a connection together of several “bipolar D.”. In them, several magnetic fields are formed between opposite poles successively located in a circle. The commutator of such magnets has either as many brushes as there are electromagnet poles, or only two, touching the commutator in places the angle between which is equal to the angle formed by the two poles in the arrangement of these poles in a circle. So, for example, in a four-pole D. the angle between the brushes is 90°. In the latter case, i.e. when using only two brushes, a special arrangement of turns in the armature winding is necessary. Rice. 11 depicts a 6-pole Schukkert-Mordey D. machine (Victoria-D.).

All kinds of D., very different from each other in appearance, but intended for the same purpose, also have something in common. In addition to the fact that in all D., for the preparation of electromagnets, thick and, as short as possible, rods of the softest iron are taken, which achieves a greater magnetic field voltage, the winding of the fittings in the machines is always made with very little resistance. In some machines, instead of wire, thick copper rods are even used to prepare fittings. The gap between the pole surfaces and the armature winding in all D. has very small dimensions, as small as possible for free rotation of the armature. D.-machines used for electric lighting most often develop a potential difference of about 100 volts on their burners (see Volt). D.-machines intended for electrolysis produce about 2 or even less volts on their borns. The current strength that can be obtained from a D. machine is completely determined by the size of the machine. This current strength varies in different D. from ten to a thousand or more amperes (see the definition of ampere in the word Volt-Ameter). The product of the number of volts on the circuits of a machine by the number of amperes delivered by the latter determines the performance of the machine, that is, it gives the number of watts (see Volt) developed by the machine in the form of electrical energy in the external part of the circuit. The quotient obtained by dividing the number of watts delivered by the driving machine by 500 determines the actual required number of horsepower in the engine, which is used to drive the armature of the driving machine (the theoretical number of horsepower corresponding to the performance of the machine is obtained from dividing number of watts at 736). The theory of dynamic machines gives the following expression (in volts) for the electromotive (electrical excitatory) force obtained in the rotating armature of a two-pole dynamic machine.

E = nNZ× 10 -8

In this formula n denotes the number of revolutions made by the armature within 1 second. when it rotates, N denotes the number of wires located on the outer surface of the armature, and Z- the so-called total number of lines of force piercing the iron core of the armature.

Calling through T the number of revolutions of the wires in the electromagnet winding, through i- current strength (in amperes) passing through the electromagnet coils, through l a- the average length of the power line inside the reinforcement iron, i.e. the average distance from the point of entry of the power lines into the reinforcement iron and the place where they exit, through s a cross section of reinforcement, through μa- magnetic permeability of iron reinforcement, through l e , s e , μ e- average length of field lines, cross-section and magnetic permeability for the gap between the reinforcement core and the pole surface and also through l m , s m μ, m , And l p , s p , μ p- the same elements for the iron of the electromagnet and the pole plates, we have, based on theory, the following (approximate) expression for Z:

4πmi = Z[(l a /(μ a s a) + l e /(μ e s e)] + NZ[(l p /(μ p s p) + l m /(μ m s m) + l e /(μ e s e)].

In this formula, N represents the ratio between the number of lines of force piercing the cross section of the middle part of the electromagnet and the number of lines of force corresponding to the core of the armature. This attitude changes along with changes in the design of D.; on average it is quite close to the number 1.4.

Quantities included in the formula μ a , μ m And μp can be found in tables representing the results of experimental studies of the magnetic properties of various types of iron; magnitude μe, i.e., the magnetic permeability of air can be taken equal to 1.

In addition to D-machines that produce a current in a constant direction, D-machines are also used in electrical engineering, which produce a current that quickly changes its direction. Such "AC D"(otherwise called alternators) together with "transformers"(see) are especially convenient in cases where it is necessary to conduct current over long distances. Recently, these machines have received significant development. Fig. 12 shows a diagram of the device of similar D. In the center of the armature, arranged like a Gram ring, but without a collector, an “inductor” rotates, which consists of several (even number) electromagnets located in the direction of the radii of the ring and facing it alternately with positive and negative poles . The inductor is usually magnetized with the help of a current obtained from some other D. machine that provides a current in a constant direction. The individual parts of the winding of the armature are connected to each other so that all the currents that appear from the electromotive forces of induction in individual parts of the winding, when the poles of electromagnets pass past these parts, i.e. when the wires of the winding are cut by power lines, have one and the same direction. The beginning of the first part of the winding and the end of its last part are represented by “borns” D. When the inductor rotates, such an armature will produce a current in the outer part of the circuit, the direction of which continuously changes. AC machines are usually designed with high voltage, that is, the potential difference resulting from the voltages of these generators is measured in a large number of volts (for example, 2000 volts or even more). AC machines designed according to the Ganz system are especially common at present. There are also alternating current D-machines, the armature winding of which is divided into 2, 3 or more parts so that 2, 3 or more separate alternating currents are simultaneously obtained from such a machine. All these currents are quite identical with each other in nature, but differ from one another "phases" that is, at the moment when one current reaches its greatest strength, the second is still just developing, while the third current has at the same moment the exact opposite direction. This system of alternating currents is called "multiphase current systems". Fig. 13 shows the appearance of a Brown machine producing "three-phase current". This machine was used to generate current in experiments on the transmission of electrical energy (see Energy transmission) from Laufen on the Neckar river in Frankfurt am Main, at a distance of 175 km, during the electrical exhibition in Frankfurt, in the fall of 1891. It rotates inside a stationary armature a system of electromagnets excited by direct current, which is obtained from a small D-machine (Fig. 13 shows a machine with shifted fittings). The electromagnet system is arranged as follows. An iron ring with two flanges on its rim is wrapped around its circumference with wire. Steel rings are screwed to this ring on both sides, each of which has 16 steel arms around its circumference. These rings are screwed so that the horns of one ring fit into the spaces between the horns of the other. When current passes through the winding of the middle iron ring, these horns turn into pole ends of alternately opposite sign. This results in 16 north and 16 south poles, located alternately one after the other. The basis of the machine’s fittings is an iron ring reinforced inside a cast-iron frame. Near the inner surface of this ring, parallel to its axis, through holes are made at equal distances from each other. Asbestos-insulated copper rods are inserted into these holes. These rods are connected into three separate systems that look like zigzag lines. Each system consists of 32 rods. The distance of the rods of one system from the corresponding rods of the next system is equal to 2/3 of the distance between the midpoints of two adjacent pole horns. When the inductor rotates, an alternating current develops in each such system. Currents appearing in two successive systems differ from each other in phase by 120°. The inductor in Brown's machine in the experiments in Laufen rotated at a speed of 150 revolutions per minute. The number of complete changes in current direction in each individual system of reinforcement conductors was 150 × 16 = 2400 per minute, or 40 per second. The voltage of each of the 3 separate currents was only about 50 volts, but the strength of each current reached 1400 amperes. The three currents produced by the machine were fed into three separate transformers. These currents passed through the thick windings of the transformers and excited very high voltage currents (up to 10,000 volts) in the thin windings of these transformers. The latter currents were transmitted through conductors (copper wires 4 mm in diameter. ) from Laufen to Frankfurt.