As the linear motor can not produce any of the intermediate conversion mechanism can produce linear motion, driving linear motion of the production machinery, so the entire device or system structure is simple, reliable, high precision, high efficiency, so in recent years at home and abroad to actively research and development One of the motors.
      There are many types of linear motors, in principle, each of the rotating motor has a corresponding linear motor. Linear motor according to its working principle is divided into: linear induction motor, linear DC motor. This paper mainly introduces the principle and classification of linear induction motor.
     Linear induction motors are mainly flat, cylindrical and disc type three types, including flat-type applications are more extensive.

      1. Flat type
      Linear motors can be seen as evolved from rotating motors. It is assumed that the rotating induction motor is cut along the radial direction and the circumference is developed in a straight line to obtain a flat type linear induction motor. The side evolved from the stator is called the primary side, and the side evolved by the rotor is called the secondary side.
      Since there is a relative motion between the primary side and the secondary side at the time of operation, it is assumed that the primary and secondary sides are aligned at the beginning of the motion, and that the primary and secondary sides are electrically coupled to each other during the movement Part of the less and less, affecting the normal operation. In order to ensure that the electromagnetic coupling between the primary and secondary sides is always constant within the required travel range, the primary and secondary sides must be made to be of different lengths for practical applications. Of course, either a short side of the side, the second side of the long, it can be a side long, second side short. The former is called the short side, the latter is called the long side. As the short side of the structure is relatively simple, manufacturing costs and operating costs are low, generally use a short side.
      The flat type linear induction motor has a primary side only on one side of the secondary side, and this type is called a unilateral type. Its greatest feature is that there is a large normal suction between the primary and secondary sides, which is undesirable in most cases. If both sides are installed on both sides of the secondary side, then the normal suction can offset each other, this structure is called bilateral type.
      The primary core of the flat type linear induction motor is stacked by a silicon steel sheet, and a groove is formed on the side opposite to the secondary side. The primary winding can be single-phase, two-phase, three-phase or multi-phase. There are two kinds of structural types on the secondary side, one is the grid structure, especially the cage structure of the rotating motor; the secondary side of the core slot, slot placed in the guide bar, and at both ends with the end of the conductor to connect all the trough In the guide. The other is a solid structure, that is, using a uniform piece of metal material, which is divided into non-magnetic secondary side and steel secondary side, non-magnetic secondary side of the conductive properties, generally copper or aluminum.
      2. Cylindrical (tube type)
      Flat type linear induction motor, it is along the linear motion and perpendicular to the direction of the roll into a cylindrical, to form a cylindrical linear induction motor. In some special occasions, this motor can also be made both rotary and linear motion of the rotating linear motor, rotating linear motion body can be a primary side, it can be secondary side.
      3. Disc type
      Disc type linear induction motor. Its secondary side is formed in a flat disc shape and is free to rotate about the axis passing through the center of the circle, placing the primary side on the plane of the secondary side disc near the outer edge so that the disc is subjected to tangential forces for rotational movement. The primary side can be single-sided or double-sided. Although it also for rotary motion, but the operating principle and design methods and flat-type linear induction motor is the same, it still belongs to the scope of linear motor. Compared with the ordinary rotating motor, has the following advantages:
      (1) The torque and rotation speed can be adjusted by means of multiple primary side combinations or by the radial position on the disc by the primary side.
      (2) no need to pass gear reducer can get a lower speed, so the motor vibration and noise is very small.
       More knowledge of linear motors, please visit Kunshan Tongmao Electronics Co., Ltd. official website: http://www.tmmotion.com/english/index.asp