The basic principle of linear motor selection, linear motor has a unique use of characteristics, is the rotary motor can not be replaced. However, it is not a good thing to use a linear motor in any situation. To do this, one must first understand the basic principles of linear motor selection so that it can be used properly. Its basic guidelines include the following four major points.
1. Appropriate movement speed: The speed of the linear motor is related to the synchronous speed, and the synchronous speed is proportional to the pole pitch. Therefore, the range of pole pitch selection determines the range of motion speed options. Too small a pole pitch will reduce the utilization of the slot, increase the slot leakage resistance and reduce the quality factor, thereby reducing the efficiency and power factor of the motor. The lower limit of the pole pitch is usually 3cm. There can be no upper limit for the pole pitch, but when the output power of the motor is constant, the longitudinal length of the primary core is limited; at the same time, in order to reduce the longitudinal edge effect, the number of poles of the motor cannot be too small, so the pitch cannot be too large.
2. Proper thrust: The linear motor can adapt to a large thrust range. The linear motors are equipped with different gearboxes to obtain different speeds and torques. At low speeds, the torque can be increased by tens to hundreds of times, so that a very small linear motor can drive a large load, and of course the power is conserved. The linear motor is different, it can not use the gearbox to change the speed and thrust, so its thrust can not be expanded. To get a larger thrust, only rely on increasing the size of the motor. This is sometimes uneconomical. In general, linear motors are suitable for driving light loads in industrial applications.
3. Appropriate reciprocating frequency: In industrial applications, linear motors are reciprocating. In order to achieve higher labor productivity, a higher reciprocal frequency is required. This means that the linear motor needs to complete the stroke in a short time. In one stroke, it needs to undergo acceleration and deceleration, that is, to start once and brake once. The higher the reciprocating frequency is, the greater the acceleration of the linear motor is, and the greater the thrust corresponding to the acceleration is, sometimes the acceleration corresponding to the thrust is even greater than the required thrust of the load. The increase of the thrust leads to the increase of the size of the linear motor, and the increase in its mass causes the thrust corresponding to the acceleration to further increase, sometimes resulting in a vicious cycle.
4. Appropriate positioning accuracy: In many applications, the linear motor is stopped by mechanical limit when it is in position. In order to make the impact small when in place, a mechanical buffering device can be added. In the case where there is no mechanical limit, a simpler positioning method is to control the motor through the limit switch before it is in place, and then make a reverse braking or energy braking to the motor so that it stops when it is in place.
This article originated from Kunshan Tongmao Electronics Co., Ltd. (
www.tmmotion.com) company original, reproduced please indicate the source.
Linear motor