Principle of linear motor
time£º2009/10/4 click£º8036
Linear motor is an electric transmission device that converts electric energy directly into linear motion mechanical energy. It can save a large number of intermediate transmission mechanisms, speed up the system reflection speed, improve the system accuracy, so it has been widely used.
The types of linear motors can be divided into structural forms; Unilateral flat, bilateral flat, disc, cylindrical(or tubular), etc.; According to the working principle can be divided into: DC, asynchronous, synchronous and stepping. The following is a brief introduction to the simple structure, convenient use, and reliable linear asynchronous motor.
The structure of linear asynchronous motor mainly includes three parts: stator, mover and support wheel of linear motion. In order to ensure a good electromagnetic field coupling between stator and mover within the stroke range, the length of the core of the stator and motor varies. The stator can be made into two forms: short stator and long stator. Due to the high cost of long stator structure and high operating cost, it is rarely used. Like a rotating magnetic field, a linear motor has a stator core that is also superimposed by a Silicon steel sheet with a toothed surface; The slot is embedded with three-phase, two-phase or single-phase windings; Single-phase linear asynchronous motor can be made into a shield type, but also through capacitance phase shift. There are three forms of Mobilizers for linear asynchronous Motors:
(1) Magnetic kinematics are made of magnetic conductive materials(steel plates) that act both as magnetic circuits and as cage kinematics.
(2) Non-magnetic Motors, which are made of non-magnetic materials(copper) and mainly play a conductive role. This form of motor has a large air gap, a large excitation current and a large loss.
(3) The surface of the kinematics magnetic guide material is covered with a layer of conductive material, and the magnetic guide material only acts as a magnetic circuit magnetic guide; Covering conductive material for cage winding.
Due to the simple structure of the linear asynchronous motor of magnetic movers, movers can not only be used as a guide magnet, conductor, or even as a structural component, and their application prospects are wide.
The working principle of a linear asynchronous motor is the same as that of a rotating asynchronous motor. The stator winding is connected to an AC power supply. After a multiphase alternating current is used, a smooth traveling wave magnetic field is generated in the air gap(when the radius of the rotating magnetic field is large, It becomes a traveling wave magnetic field that moves in a straight line.) The magnetic field moves straight along the air gap. At the same time, the electromotive force is induced in the moving conductor and a current is generated. This current interacts with the traveling wave magnetic field to generate asynchronous driving force, causing the moving force to move straight along the direction of the traveling wave. If the power phase sequence in the stator winding of the linear asynchronous motor is changed, the direction of movement of the traveling wave magnetic field will also be reversed. According to this principle, the linear asynchronous motor can be reciprocated linear motion.
Linear asynchronous motors are mainly used for linear motion mechanisms with higher power, such as door automatic opening and closing devices, mechanical equipment for lifting, transmitting and lifting, and driving vehicles, especially for high-speed and speeding transportation. Since traction or driving force can be directly generated, there is no need for intermediate joint parts, no friction, no noise, no rotor heat, and no centrifugal force. Therefore, its application will become more and more extensive. Because of its superior performance, linear synchronous motors have the same trend as linear asynchronous motors in applications. Linear stepping motor is used in NC plotter, recorder, digital control plotter, NC cutter, disk memory, precision positioning mechanism and so on.
Linear motor