Motor is a device that converts electrical energy into mechanical energy, and the function of linear motor is to convert electrical energy into mechanical energy of linear motion. In the actual production, more occasions need linear motion, often through the necessary conversion device, the rotary motion into linear motion, and linear motor can directly produce linear motion, can simplify the equipment conversion link. Linear motor includes DC, synchronous, asynchronous, stepping and special types. We take linear asynchronous motor as an example to communicate with you.

Compared with the rotating motor, we can make an intuitive comparison from the motion space, trajectory and operation mode. The main differences between linear induction motor and rotary induction motor are as follows

For a rotating motor, the air gap between the stator and rotor is a closed ring in theory, and the rotor rotates during the operation of the motor. In linear motor, the moving parts are called sliders. The air gap between the stator and the sliders is strip, and the sliders slide linearly relative to the stator.

Because the electromagnetic air gap of linear induction motor (2-10 mm) is much larger than that of rotating motor (0.2-1 mm), and the influence of end effect, the power factor and efficiency of linear induction motor are lower than that of rotating motor with the same capacity.

The three-phase stator windings of the rotating machine are symmetrical, so the three-phase current is symmetrical under the premise of three-phase symmetry of the power grid and no winding fault; However, the spatial position of the stator winding of the linear motor is asymmetric, the inductance of the edge coil is very different from that of the middle coil, and the reactance of the three-phase winding is inconsistent. Therefore, even if the grid is symmetric, the three-phase current is asymmetric.

Compared with rotary motor, the performance calculation and analysis of linear motor are more complex due to the asymmetry of circuit and magnetic circuit, as well as the side effect.

With the continuous improvement of operation and control, linear motor has been better promoted and applied, for example, in the application of ground adjustment and transportation, which better reflects the advantages of linear motor: linear motor has no mechanical and friction loss, is not limited by centrifugal force and diameter, has no slide heating problem, and has low noise. At present, linear motor is used in rail transit, elevator, punch, compressor, CNC machine tools and other fields.