Generator structure and working principle

Generators are usually composed of stators, rotors, end covers, bearings and other components.

The stator consists of the stator core, wire windings, machine base and other structural parts that fix these parts.

The rotor is composed of rotor core (or magnetic pole, magnetic yoke) winding, retaining ring, center ring, slip ring, fan and rotating shaft.

The stator and rotor of the generator are connected and assembled by the bearings and end covers, so that the rotor can rotate in the stator and perform the motion of cutting the magnetic lines of force, thus generating an induced electric potential, which is led out through the terminals and connected to the circuit , an electric current is generated.

Working principle of diesel generator

The diesel engine drives the generator to operate, converting the energy of diesel into electrical energy.

In the diesel engine cylinder, the clean air filtered by the air filter is fully mixed with the high-pressure atomized diesel fuel injected from the injector. Under the upward squeeze of the piston, the volume shrinks and the temperature rises rapidly. High, reaching the ignition point of diesel. The diesel is ignited, the mixed gas burns violently, expands rapidly in volume, and pushes the piston downward, which is called 'work'. Each cylinder performs work in a certain order, and the thrust acting on the piston becomes the force that drives the crankshaft to rotate through the connecting rod, thereby driving the crankshaft to rotate.

By installing the brushless synchronous alternator coaxially with the crankshaft of the diesel engine, the rotation of the diesel engine can be used to drive the rotor of the generator. Using the principle of 'electromagnetic induction', the generator will output an induced electromotive force. The load circuit can generate current.

Here is only the most basic working principle of the generator set. In order to obtain usable and stable power output, a series of diesel engine and generator control, protection devices and circuits are also required. For details, please go to >>>

Principle of gasoline generator

The gasoline engine drives the generator to operate, converting the energy of gasoline into electrical energy.

In the cylinder of a gasoline engine, the mixed gas burns violently, expands rapidly in volume, and pushes the piston downward to perform work. Each cylinder performs work in a certain order, and the thrust acting on the piston becomes the force that drives the crankshaft to rotate through the connecting rod, thereby driving the crankshaft to rotate. By installing the brushless synchronous alternator coaxially with the crankshaft of the gasoline engine, the rotation of the gasoline engine can be used to drive the rotor of the generator. Using the principle of 'electromagnetic induction', the generator will output an induced electromotive force, and a current can be generated through the closed load loop. . For details, please go to >>>

Working principle of synchronous generator

· Establishment of main magnetic field: DC excitation current is passed through the excitation winding to establish an excitation magnetic field with alternating polarities, that is, a main magnetic field.

· Current-carrying conductor: The three-phase symmetrical armature winding acts as a power winding and becomes the carrier of induced electric potential or induced current.

· Cutting motion: The prime mover drags the rotor to rotate (inputting mechanical energy to the motor), and the excitation magnetic field of alternate polarity rotates with the shaft and cuts each phase winding of the stator in sequence (equivalent to the reverse direction of the conductor of the winding) cutting excitation magnetic field).

· Generation of alternating electric potential: Due to the relative cutting motion between the armature winding and the main magnetic field, a three-phase symmetrical alternating electric potential whose magnitude and direction changes periodically will be induced in the armature winding. . Through the lead wire, AC power can be provided. Please go to >>>

Principle of asynchronous generator

Working principle of DC generator

The working principle of DC generator is to induce induction in the armature coil The alternating electromotive force generated depends on the commutation effect of the commutator and the brush, so that it becomes a DC electromotive force when it is drawn from the brush end.

No DC voltage is applied to the brush, and the prime mover is used to drag the armature to rotate counterclockwise at a constant speed. The two sides of the coil cut the magnetic lines of force under the magnetic poles of different polarities, and the electromotive force is induced in them. , the direction of the electromotive force is determined according to the right-hand rule. This electromagnetic situation is represented on the diagram. Since the armature rotates continuously, it is necessary that the coil sides ab and cd experienced by the current-carrying conductor in the magnetic field alternately cut the magnetic lines of force under the N pole and S pole. Although the induced electromotive force of each coil side and the entire coil is The direction is alternating. The induced electromotive force in the coil is an alternating electromotive force, while the electromotive force at the A and B ends of the brush is a DC electromotive force (to be more precise, it is a pulsating electromotive force with a constant direction). Because, during the rotation of the armature, no matter where the armature rotates, due to the commutation effect of the commutator and the brush, the electromotive force induced by the brush A through the commutator piece is always in the edge of the coil cutting the N-pole magnetic lines of force. electromotive force, therefore, brush A always has positive polarity. In the same way, brush B always has negative polarity, so the brush end can induce a pulse vibration electromotive force with the same direction but changing magnitude. If the number of coils under each pole is increased, the degree of pulse vibration can be reduced, and DC electromotive force can be obtained. This is how a DC generator works. It also shows that a DC generator is essentially an alternator with a commutator.

From the basic electromagnetic situation, in principle, a DC motor can operate as a motor or a generator, but the constraints are different.

On the two brush ends of the DC motor, DC voltage is added, the electrical energy is input into the armature, and the mechanical energy is output from the motor shaft to drive the production machinery. The electrical energy is converted into mechanical energy to become an electric motor. For example, a prime mover is used to drive a DC motor. armature, and no DC voltage is applied to the brush, the brush end can draw out DC electromotive force as a DC power supply, which can output electrical energy. The motor converts mechanical energy into electrical energy and becomes a generator. This is the principle that the same motor can be used as a motor or a generator. In motor theory it is called the reversible principle. For details, please go to >>>

The working principle of the alternator

Please click to view the demonstration of the alternator principle

The principle of the turbine generator

A steam engine uses the expansion of high-temperature and high-pressure steam to do work, and converts the reciprocating motion of the piston into the rotational motion of the main shaft through the connecting rod and crank, driving the generator to generate electricity.

A steam turbine uses steam to push the turbine to rotate. The basic principle of its operation is similar to that of a common windmill. The steam turbine is composed of a thick steel plate in the center and many densely packed steel plates on the outer edge of the steel plate. The main structure consists of blades. When the high-pressure superheated steam from the boiler is sprayed from the nozzle onto the blades, the turbine starts to rotate. The greater the steam speed, the faster the turbine rotates (that is, the internal energy of the steam changes into the kinetic energy of the steam during the injection, and its kinetic energy And converted into the mechanical energy of the rotation of the machine shaft). For details, please go to >>>

Principle of hydraulic generator

The installation structure of the hydraulic generator is usually determined by the type of hydraulic turbine. There are mainly the following types:

1) Horizontal structure Hydroelectric generators of horizontal structure are usually driven by impact turbines.

2) Vertical structure Domestic hydroelectric generator sets widely adopt vertical structure. Vertical turbine generator sets are usually driven by Francis or axial flow turbines. Vertical structures can be divided into suspended and umbrella types. The thrust bearings of generators located on the upper part of the rotor are collectively called suspension type, and those located on the lower part of the rotor are collectively called umbrella type.

3) Tubular structure The tubular turbine generator set is driven by a tubular turbine. A tubular turbine is a special type of axial flow turbine with fixed or adjustable runner blades. Its main feature is that the runner axis is arranged horizontally or tilted, and is consistent with the water flow direction of the turbine inlet and outlet pipes. The tubular turbine generator has the advantages of compact structure and light weight, and is widely used in low-head power stations. For details, please go to >>>

Principles of hand-operated generators

Principles of wind energy generators

Principles and applications of new water-cooled alternators

Water-cooled alternators use water instead of a fan for cooling. The main heating part of the alternator is the stator, and the key cooling parts of the water-cooled alternator are the stator and coil windings. The front end cover and rear end cover of the generator are made of aluminum and have water channels. The stator and coil windings are fixed and sealed with synthetic resin, and there are aluminum enclosures between the stator and the rotor to isolate them from the water channel. The water channel is connected to the water inlet pipe and the water outlet pipe, and the water inlet pipe and the water outlet pipe are connected to the engine cooling water system respectively.

In this way, when the engine is running, the cooling water circulates under the drive of the engine water pump. Through the generator casing, it can effectively cool the stator coil windings and stator core, as well as the rotor and built-in Regulators and bearings and other heating parts.

Compared with air-cooled alternators, water-cooled alternators have a more complex internal structure, higher leak-proof sealing requirements, and increased costs. At the same time, due to the problem of connecting water pipes, the installation layout is also subject to many restrictions, and the degree of freedom is reduced. However, the power generation and low noise performance of water-cooled alternators are unmatched by air-cooled alternators.

First, water-cooled alternators have good low-speed charging characteristics. We know that there is an "inflection point" on the current characteristic curve of the alternator, that is, the current will not be generated until it exceeds the so-called "0 ampere speed", and the current can only be charged when the current rises to a certain level. Above which speed does the "inflection point" appear and the charging current is reached is related to the size of the excitation current.

Since the water-cooled alternator greatly suppresses the temperature rise of the stator, rotor and regulator, the excitation current can be increased accordingly. The larger the excitation current, the higher the output voltage. Therefore, when the water-cooled alternator It also has good charging performance when rotating at low speeds. This low-speed charging performance is very important for the normal use of city cars.

Second, water-cooled alternators have low noise. Since the fan is omitted, there is no noise from the generator fan. According to reports, at 3,500 rpm, the noise of a water-cooled alternator is 15 decibels lower than that of an air-cooled alternator.

The advantages of water-cooled alternators are favored and considered to be the development direction of automobile generators. Some people think that in 12-volt cars, air-cooled alternators are suitable for power supplies below 2500 watts, and water-cooled alternators are suitable for power systems above 2500 watts or 42 volts.

The leverage principle is also known as the "leverage balance condition". For a lever to be balanced, the magnitudes of the two forces acting on the lever (power point, fulcrum, and resistance point) are inversely proportional to their moment arms. Power × power arm = resistance × resistance arm, expressed in algebra as F1? L1=F2? L2.

In the formula, F represents power, L1 represents power arm, F2 represents resistance, and L2 represents resistance arm. It can be seen from the above formula that in order for the lever to reach balance, the power arm is several times the resistance arm, and the power is a fraction of the resistance.

When using a lever, in order to save effort, you should use a lever with a power arm that is longer than the resistance arm; if you want to save distance, you should use a lever with a power arm that is shorter than the resistance arm. Therefore, using leverage can save effort and distance. However, if you want to save effort, you must move more distance; if you want to move less distance, you must expend more effort. It is impossible to achieve both labor saving and moving distance. It was from these axioms and on the basis of the "center of gravity" theory that Archimedes discovered the lever principle, that is, "when two heavy objects are balanced, their distance from the fulcrum is inversely proportional to their weight.

The fulcrum of the lever does not have to be in the middle. A system that satisfies the following three points is basically a lever: fulcrum, force-applying point, and force-receiving point.

The formula is as follows: the distance from the fulcrum to the force-receiving point ( Torque) * Force = distance from fulcrum to force application point (force arm) * force, this is a lever.

There are also effortless levers and effortless levers, both of which have different functions. For example. There is a foot-operated air pump or a hand-pressed juicer, which is a labor-saving lever (force arm > torque); but we need to press a larger distance, and the force-receiving end only has a small movement. A kind of laborious lever. For example, in the crane on the roadside, the hook for fishing is at the tip of the whole rod, the tail end is the fulcrum, and the middle is the hydraulic press (torque > moment arm). This is the laborious lever, but the reward for the labor is the middle. As long as the force application point moves a small distance, the hook at the tip will move a considerable distance.

Both levers have their uses, but they need to be evaluated to save effort or to save the range of motion. . There is another thing called an axle, which can also be used as a lever, but the performance may sometimes include calculations of rotation.

The ancient Greek scientist Archimedes has this saying that has been passed down through the ages. His famous saying: "If you give me a fulcrum, I can move the earth!" This sentence is not only an inspiring aphorism, but also has a strict scientific basis.