In the cylinder of a gasoline engine, the gas mixture burns violently, expands rapidly in volume, and pushes the piston down to do work. Whether it is a diesel generator or a gasoline generator, each cylinder performs work in a certain order. The thrust acting on the piston becomes the force that causes the crankshaft to rotate through the connecting rod, thereby causing the crankshaft to rotate.
By installing the brushless synchronous alternator coaxially to the crankshaft of the electric machine, the rotation of the electric machine can be used to drive the generator rotor. Using the principle of "electromagnetic induction", the generator. will produce an induced electromotive force. The charging circuit can generate current.
Detailed information:
Main features of the generator:
1. Operating characteristics:
The performance of synchronous generators is mainly characterized by the no-load characteristics and the load operating characteristics. These features provide an important basis for users to choose generators.
2. No-load characteristics:
When the generator is not connected to a load, the armature current is zero, which is called no-load operation. At this time, the three-phase winding of the motor stator only has the no-load electromotive force E0 (three-phase symmetry) induced by the excitation current If, and its size increases with the increase of If. However, due to the saturation phenomenon in the core of the motor's magnetic circuit, the two are not proportional. The curve reflecting the relationship between the no-load electromotive force E0 and the excitation current If is called the no-load characteristic of the synchronous generator.
3. Armature reaction:
When the generator is connected to a symmetrical load, the three-phase current in the armature winding will produce another rotating magnetic field, called the armature. reaction magnetic field. Its speed is exactly equal to the speed of the rotor and the two rotate synchronously.
The armature reaction magnetic field and the excitation magnetic field of the synchronous generator rotor can be approximately considered to be distributed according to the sinusoidal law. The spatial phase difference between them depends on the temporal phase difference between the no-load electromotive force E0 and the armature current I.
The armature reaction magnetic field is also related to the state of charge. When the generator load is inductive, the armature reaction magnetic field acts as a demagnetizer, which will cause the generator voltage to decrease; when the load is capacitive, the armature reaction magnetic field acts as a mmagnetizer, which will reduce the generator voltage; the generator output voltage increases.
4. Load operating characteristics:
Mainly refers to external characteristics and adjustment characteristics. The external characteristic is the relationship between the generator terminal voltage U and the load current I when the speed is the rated value, the excitation current and the load power factor are constant. The setting characteristic is the relationship between the excitation current If and the load current I when the speed and terminal voltage are nominal values and the load power factor is constant.
The voltage change rate of a synchronous generator is approximately 20 to 40%. Typically, industrial and domestic loads require the voltage to remain virtually unchanged. For this reason, as the load current increases, the exciting currenttation must be adjusted accordingly. Although the change trend of the fitting characteristic is exactly opposite to that of the external characteristic, for inductive and purely resistive loads it increases, while for capacitive loads it generally decreases.
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