1.Working principle of linear stepper motor
A linear stepper motor is a motor that drives a slider to move along a straight line through an electromagnetic field. Its working principle is mainly to generate an alternating magnetic field by alternately exciting electromagnets, and this magnetic field pushes the slider to move along a straight line. When one electromagnet is activated, the magnetic field it generates attracts the slider and moves toward it; when the other electromagnet is activated, the opposite magnetic field generated pushes the slider to move in the opposite direction. By alternately activating these two electromagnets, the slider can reciprocate along a straight line.
2.Structural characteristics of linear stepper motors
1.High precision: The direct drive structure has no backlash, the system accuracy mainly depends on the position detection element, and the appropriate feedback device can reach the sub-micron level.
2.High acceleration and speed: The linear motor has achieved an acceleration of 5.5g and a speed of 2.5m/s.
3.No mechanical contact wear: There is no mechanical contact between the stator and the mover, and the system motion contact is borne by the linear guide. There are fewer transmission parts, smooth operation, low noise, simple structure, simple maintenance, or even maintenance-free, high reliability, and long service life.
4.Modular structure: The stator adopts a modular structure, and the running stroke is theoretically unlimited.
5.Strong adaptability: The primary core can be sealed as a whole with epoxy resin, which has good anti-corrosion and moisture-proof properties and is easy to use in harsh environments.
3.Control methods of linear stepper motors
1.Open-loop control: This is the most basic control method, which controls the position and speed by directly controlling the current size and direction. Its advantage is simple control, but its disadvantage is that the control accuracy is not high and it is easily affected by external interference.
2.Closed-loop control: By installing position feedback sensors such as encoders to obtain position and speed information, and then adjusting the motor current through the controller to achieve the purpose of controlling the position and speed of the motor. This method has high control accuracy, but the cost is high.
3.Full-step control: Each pulse signal causes the motor to rotate a full step angle, which is suitable for applications that require high-precision positioning.
4.Half-step control: Improved on the basis of full-step control, each pulse signal causes the motor to rotate half a step angle, with a faster speed but lower accuracy. 5. Microstepping control: By changing the pulse width or phase, the motor rotates with a smaller step angle, which is suitable for high-precision and high-dynamic applications.
6.Current control: By adjusting the current flowing through the motor to control the torque and speed, it is suitable for applications that require smooth rotation.
7.PID control: A feedback control method that adjusts the motor torque by measuring the error between the actual position and the target position, which is suitable for complex and high-dynamic applications.
8.Vector control: Using the motor mathematical model to optimize performance, it is suitable for applications with high performance and reliability requirements.
4.Precautions for installing linear stepper motors
1.Avoid disassembling motor components: During installation and maintenance, avoid disassembling any part of the motor by yourself, as disassembly may cause foreign matter to enter or affect assembly accuracy.
2.Protect the lead screw and lead wires: When installing and taking the motor, be careful not to lift, pull, or hold the lead screw directly with your hands to avoid radial force on the lead screw; at the same time, protect the lead wires of the motor and do not pull them hard.
3.Choose a suitable installation environment: Clean the site before installation to ensure that there are no debris and obstacles, check whether the foundation of the motor is firm, and the levelness and firmness must meet the requirements.
4.Avoid vibration and wiring errors: Avoid direct impact on the shaft during installation, and use a flexible connector to connect the encoder shaft; wiring should be done when the power is off, pay attention to the power polarity and line distribution, and avoid inductive noise.
5.Pay attention to the operating temperature of the motor: Ensure that the operating environment temperature of the motor is between -20℃~55℃ to avoid overheating of the motor due to long-term operation.
6.Correct installation and debugging: Select the appropriate motor specifications according to the installation environment and motion status, ensure that the installation is firm, the circuit connection is correct, and the voltage and current meet the requirements; adjust the motor speed and acceleration during debugging, and check the motor operation status.
By following these precautions, the service life of the linear stepper motor can be effectively extended and its operating efficiency and reliability can be improved.
