Ⅱ, Generators classification can be summarized as follows:
Generator points: DC generators and AC generators;
AC generators: synchronous generators and asynchronous generators (seldom used);
Alternator can be divided into single-phase and three-phase generator.

Ⅲ, Generators structure and working principle
Generators are normally composed of  the stator and rotor, end caps and bearings and other components.
Stator is composited by the stator core, winding line package, these fixed-Block and other parts of the structure.
Rotor is composited by the rotor core (or magnetic pole, magnetic recapped) winding, retaining ring, the center ring, slip ring, the fans and shaft and others.
By bearings and will cover the generator stator and rotor assembly connected, so that the rotor to the stator in the rotation, so cutting magnetic line of movement, resulting in induction potential, through the Connection leads, and then in the loop, it produced a current.
 

Diesel generators working principle
Diesel-driven generators functioning, diesel energy into electricity.
In cylinder engine, air filter through the clean air filter with a jet nozzle atomizing the high-voltage full hybrid diesel, squeezed up in Detroit, the volume of narrow, the temperature rapidly increased, reaching the ignition of diesel. Diesel fuel was ignited, burning gas mixture intense, rapid expansion of volume, to promote the Pistons down, called 'a work'. The cylinder by a certain order of a reactive, role in Detroit's thrust to promote the linkage into the crankshaft rotational force, thus boosting crankshaft rotation.
Brushless alternator will be synchronized installed with the engine crankshaft coaxial, they can use the rotary engine driven generator rotor, the use of 'electromagnetic induction' principle, generators will be EMF sensor output, the closed loop can be generated from the load current. Units described here only the most basic working principle. To be available, stable power output, also need a series of diesel generators and control, protection devices and circuits.

Gasoline engine-driven generator running, the gasoline energy into electricity.
In the cylinder gasoline engine, hybrid gas combusts intensely, rapid expansion of volume, to promote the Pistons down to work. The cylinder by a certain order of a reactive, role in Detroit's thrust to promote the linkage into the crankshaft rotational force, thus boosting crankshaft rotation. Brushless alternator will be synchronized with the gasoline engine crankshaft coaxial installed, they can use the gasoline engine driven generator rotor rotation, the use of 'electromagnetic induction' principle, generators will be EMF sensor output, the closed loop can be generated from the load current.

? the establishment of the main magnetic field: a DC-field winding excitation current, the establishment of polar-and the exciting field, that is, to establish the main magnetic field.

? carrier conductor: symmetric three-phase power as the armature winding winding, sensing a potential or induced current carrier.

? cutting campaign: The original motivation drag rotor rotation (mechanical energy to electrical input), polar-and exciting field with a rotating shaft and sequential cutting of the stator windings (equivalent to the conductor winding excitation reverse cutting magnetic field).
? reference to the formation of transforming potential: As the armature winding and the main magnetic field between the relative cutting campaign, will be in the armature winding induction to the size and direction of the cyclical changes in the three-phase symmetrical cross transforming potential. Through the line to provide AC power.

DC generator works’ principle
DC generator is the working principle of the armature coil in the induction of the alternating EMF, on commutator with the brush for the role, so that leads from the brush at the side into the DC EMF principle.

Brush not on the DC voltage, with the original motivation to drag the armature of the anti-clockwise rotation constant speed, coil on both sides were cutting different polarity of the magnetic pole line in which sensors produce EMF, EMF direction of the Right-hand Rule Identified. Electromagnetic expressed in this map. As the armature for the rotation, therefore, the current-carrying conductor must be made in the magnetic field in the coils by the ab-cutting and cd alternately S and N is a line under the magnetic force, although each side and the entire coil in the induction coil of electromotive force Alternating the direction. The induction coil within the EMF is a alternating EMF, and in the brush A, B side of the EMF is for DC EMF (the exact number is right, is a direction the same vein-emf). This is because the armature in the rotation process, no matter what position to the armature, the commutator brush with the change to the role, through the brush-A leads to the film by the EMF is always cutting a magnetic line of the N side of the coil The EMF, so there are always brush A polarity. Similarly, B has always been a negative brush, brush-it can lead the direction of the same size but changes in the clock-emf. If every great increase in the number of coils, the clock can reduce the level of vibration, can be DC EMF. This is the principle of DC generator. At the same time also shows that sub-DC generator is essentially a commutator alternator.

From basic electromagnetic situation, in principle a DC motor can work for the motor running, can also run as a generator, only bound by the different conditions. DC motor in the two brush-on, and DC voltage, power will enter the armature, machinery output from the motor shaft, dragging the production machinery, will be converted into electrical energy into mechanical energy and motor, such as the original motivation drag the DC motor armature, and not brush on the DC voltage, the brush can lead DC-DC power supply as EMF, the output power, the electrical will be converted into mechanical energy into electricity generators. The same motor, motor can make or generators running this principle. In theory, known as reversible motor principle.

Turbogenerator Principle
The steam engine using high temperature and high pressure steam expansion of the Work, through linkage, the Pistons will crank reciprocating change as the principal axis of rotation, driven generator power.

Steam Turbine is a steam turbine to promote the rotation, it functioning of the basic principles and common windmill similar steam turbine is a central thick steel-and-steel outer row, many of the leaves of the main structure . From the boiler in the high-pressure superheated steam out of the spray nozzle from the leaves, turning on the turbines, steam greater speed, the faster rotating turbines (that is, within the steam in a steam jet in the kinetic energy, its kinetic energy Also for the change of rotating mechanical energy).

Hydrogenerator Principle
Hydrogenerator structure of the installation is usually determined by the type of turbine. There are several types:
1) horizontal structure: horizontal structure of the hydro-generator turbine usually have impacted driver.

2) vertical structure: Domestic Hydrogenerator group widely used vertical structure. Vertical Hydrogenerator group usually by Francis or axial turbine-driven. Vertical structures can be divided into the hanging-and umbrella. Generator rotor thrust bearings in the upper-collectively known as the hanging in the lower part of the rotor collectively referred to as umbrella.
 
3) Tubular Structure: turbine generators group is run by tubular turbine-driven. Tubular turbine is a runner with fixed or adjustable axial turbine blades of the special type. Its main characteristic is the runner axis tilted to the level or layout, and turbine into the outlet pipe water mains and the same direction. Turbine generators are compact, light weight advantages, widely used in low-head power plants.