The structure and principle diagram of the generator are as follows:
1. The composition of the generator:
Generate electricity The machine usually consists of a stator, a rotor, and a generator usually consists of a stator, a rotor, a generator end cover, a bearing, and other components. The stator consists of the stator core, wire windings, base and other structural parts that fix these parts. The rotor is composed of rotor core 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.
2. Working principle of generator:
Synchronous generator works based on the principle of electromagnetic induction. It uses the relative motion of the rotor magnetic field and the stator winding. Convert mechanical energy into electrical energy.
When the rotor is driven by an external force, the rotor magnetic field and the stator conductor move relative to each other, that is, the conductor cuts the magnetic lines of force, so an induced electromotive force is generated in the conductor, and its direction can be determined according to the right-hand rule. Since the position of the rotor poles causes the conductors to cut the magnetic field lines in a vertical direction, the induced electromotive force in the stator winding is maximum at this time.
When the magnetic pole rotates 90 degrees. The magnetic pole is in a horizontal position, the conductor does not cut the magnetic field lines, and its induced electromotive force is zero. When the rotor rotates another 90 degrees, the timing stator winding cuts the magnetic field lines in the vertical direction again, causing the induced electromotive force to reach the maximum value, but in the opposite direction to the previous one.
When the rotor rotates 90 degrees, the induced electromotive force becomes zero again. In this way, the rotor rotates once, and the induced electromotive force of the stator winding also changes positively and negatively. If the rotor continues to rotate at a constant speed, a periodically changing alternating electromotive force is induced in the stator winding.
Generally, the stator will be wound with a coil; the rotor is installed and fixed on the base through bearings or bushings. There are silicon steel sheets on the rotor. The rotor of the DC motor will also be wound with coils. When When they are all in working condition, the current will generate a magnetic field on the silicon steel sheets of the stator and rotor under the action of the coil, and the magnetic field will drive the rotor to rotate.
The stator of an asynchronous motor is composed of the stator core, stator windings and frame
1. Stator core
The function of the stator core is to serve as the motor magnet. part of the circuit and embedded stator windings. The stator core is made of 0.5mm thick silicon steel sheets. Both sides of the brick steel sheets are coated with insulating paint to insulate the sheets from each other to reduce the core loss caused by the rotating magnetic field in the stator core. There are several identical slots punched in the inner circle of the stator core to embed the stator windings.
2. Stator winding
The stator winding is the circuit part of the motor. Its main function is to pass current and generate induced potential to realize the conversion of electromechanical energy. Set the winding coil in the stator slotInternal distribution is divided into single layer and double layer. In order to obtain better electromagnetic performance, medium and large ABB asynchronous motors use double-layer short-pitch windings.
3. Stator base
The main function of the base is to fix and support the stator core, so it is required to have sufficient mechanical strength and stiffness to withstand the operation or transportation of the motor. various forces in it. Medium and small AC motors generally use cast iron frames. For larger capacity AC motors, steel plate welded frames are generally used.
The rotor of an asynchronous motor is composed of a rotor core, a rotor winding and a rotating shaft.
1. Rotor core
The rotor core is part of the magnetic circuit of the motor. Together with the stator core and air gap, it forms the entire magnetic circuit of the motor. The rotor core is generally made of 0.5mm thick silicon steel sheets. Most of the rotor cores of medium and small AC motors are directly installed on the motor shaft. The rotor core of a large AC motor is installed on the rotor bracket, and the bracket is sleeved on the rotating shaft.
2. Rotor winding The function of the rotor winding is to induce electric potential, flow current and generate electromagnetic torque. Its structural forms include squirrel cage type and wire wound type.
1． Squirrel-cage rotor
The squirrel-cage rotor winding is a self-closing winding. A guide bar is inserted into each rotary slot. At the slots protruding from both ends of the iron core, two end rings connect the two ends of all the guide bars respectively. A6 If the iron core is removed, the shape of the entire winding is like a "round cage", so it is called a squirrel cage rotor.
2. Wire-wound rotor
The wire-wound rotor is similar to the fixed winding. It is a three-phase symmetrical winding with insulated wires embedded in the rotor core slot and connected to form a star. Then connect the three small wire ends to the three collecting rings on the shaft, and then draw the current out through the brushes. The characteristic of the wound rotor is that external resistors can be connected to the rotor winding circuit through collector rings and brushes to improve the starting performance of the motor or adjust the speed of the motor. In order to reduce the wear of the brushes, the wound asynchronous motor is sometimes equipped with a brush-lifting short-circuit device, so that when the motor is started and the speed does not need to be adjusted, the brushes are lifted up and the three collector rings are short-circuited at the same time.