AC motors are composed of a stator and a rotor
Release time:
2021-11-22 19:12
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AC motors are composed of a stator and a rotor. AC motors are divided into two types: synchronous AC motors and induction motors. In both motors, the stator-side winding is supplied with alternating current to generate a rotating magnetic field, but the rotor winding of a synchronous AC motor usually requires an excitation machine to supply direct current (excitation current); while the induction motor does not need to be supplied with current to the rotor winding.
The stator winding of a three-phase AC motor is basically three coils separated by 120 degrees, which are connected in a delta or star shape. When a three-phase current is applied, a magnetic field is generated in each coil, and the three magnetic fields are combined to obtain a rotating magnetic field. The current completes a full vibration, and the rotating magnetic field makes exactly one revolution. Therefore, the number of revolutions per minute of the rotating magnetic field is N=60f. Where f is the power frequency.
Classification of AC motors
Classification of AC motors [4]
AC motors can be divided into synchronous motors and asynchronous motors (or non-synchronous motors) according to the speed of rotor rotation. Regardless of the size of the load, the rotor speed of the synchronous motor is always the same as the speed of the rotating magnetic field. Therefore, this speed is called the synchronous speed. As mentioned above, it only depends on the frequency of the power supply. The speed of an asynchronous motor is not constant, it depends on the size of the load and the power supply voltage. Three-phase asynchronous motors are divided into motors without commutator and motors with commutator. Most of the asynchronous motors in practical application are induction motors without rectifiers (but the three-phase asynchronous commutator motors in parallel and series have the advantages of being able to adjust the speed in a large range and have high power factor), and their speed is always less than the synchronous speed
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Steady state model control method
Commonly used steady-state model control schemes include open-loop constant v/f ratio control (ie voltage/frequency = constant) and closed-loop slip frequency control.
With the development of power electronics technology, microelectronics technology, digital control technology and control theory, the dynamic and static characteristics of the AC drive system are completely comparable to the DC drive system.
The structure of a synchronous motor is roughly the same as that of an alternator. The basic difference between it and an induction motor is that its rotor is a protruding magnetic pole with a coil, and another exciter is used to pick up the direct current and the alternating current)
The induction motor is also called "asynchronous motor", that is, the rotor is placed in a rotating magnetic field, and under the action of the rotating magnetic field, a rotating torque is obtained, so the rotor rotates.
AC motors are composed of a stator and a rotor
AC motors are composed of a stator and a rotor. AC motors are divided into two types: synchronous AC motors and induction motors. In both motors, the stator-side winding is supplied with alternating current to generate a rotating magnetic field, but the rotor winding of a synchronous AC motor usually requires an excitation machine to supply direct current (excitation current); while the induction motor does not need to be supplied with current to the rotor winding.
An AC motor is a device that converts AC electrical energy into mechanical energy. The AC motor is mainly composed of an electromagnet winding or distributed stator winding to generate a magnetic field and a rotating armature or rotor. The motor is made by using the phenomenon that the energized coil rotates under a force in a magnetic field. AC motors are divided into two types: synchronous AC motors and induction motors.
