Synchronous motors are classified into synchronous generators and synchronous motors. The AC machine in modern power plants is dominated by synchronous motors.
working principle
◆The establishment of the main magnetic field: the excitation winding is connected with the DC excitation current to establish the excitation magnetic field between the polar phases, that is, the main magnetic field is established.
◆ Current-carrying conductor: The three-phase symmetrical armature winding acts as a power winding and becomes a carrier for inductive potential or induced current.
◆Cutting movement: The prime mover drags the rotor to rotate (the mechanical energy is input to the motor), and the excitation magnetic field between the polar phases rotates with the shaft and sequentially cuts the stator phase windings (corresponding to the conductors of the windings to cut the excitation magnetic field).
◆ Generation of alternating potential: Due to the relative cutting motion between the armature winding and the main magnetic field, a three-phase symmetric alternating potential whose magnitude and direction change periodically will be induced in the armature winding. AC power is available through the lead wires.
◆ Interchangeability and symmetry: Due to the polarity of the rotating magnetic field, the polarity of the induced potential is alternating; due to the symmetry of the armature winding, the three-phase symmetry of the induced potential is guaranteed.
Operation mode
◆ There are three main operating modes of synchronous motors, namely, they operate as generators, motors and compensators. Running as a generator is the most important mode of operation for synchronous motors. As a motor, it is another important mode of operation for synchronous motors. The power factor of the synchronous motor can be adjusted. When the speed regulation is not required, the application of a large synchronous motor can improve the operating efficiency. In recent years, small synchronous motors have begun to find more applications in variable frequency speed control systems. The synchronous motor can also be connected to the grid as a synchronous compensator. At this time, the motor does not carry any mechanical load, and the excitation current in the rotor is adjusted to send the required inductive or capacitive reactive power to the grid to achieve the purpose of improving the power factor of the grid or adjusting the voltage of the grid.
Synchronous generators, like other types of rotating electrical machines, consist of a fixed stator and a rotatable rotor. Generally divided into transition synchronous motor and pivot synchronous motor.
The most commonly used is a synchronous synchronous generator. The inner circumference of the stator core is evenly distributed with the stator slots, and the three-phase symmetric windings arranged regularly are embedded in the slots. The stator of such a synchronous machine is also called an armature, and the stator core and the winding are also called an armature core and an armature winding.
The rotor core is provided with a pair of magnetic poles of a certain shape, and a magnetic winding is wound around the magnetic pole. When a direct current is applied, a magnetic field between the polar phases is formed in the air gap of the motor, which is called an excitation magnetic field (also called a main magnetic field). Magnetic field, rotor magnetic field).
The prime mover drags the rotor to rotate (the mechanical energy is input to the motor), and the excitation magnetic field between the polar phases rotates with the shaft and sequentially cuts the stator phase windings (corresponding to the conductors of the windings to cut the excitation magnetic field).
