来源：http://www.jnmcd.com 发布时间：2019-06-28 浏览：次
In the condition that the equipment (motor and driver) is not damaged, the blockage is that the motor torque is insufficient. In the condition of fixed stepping motor, the main factors affecting the torque are speed and current. The higher the speed, the smaller the torque and the smaller the current.
Stepper motor can only be controlled by digital signals. When the pulse provides the driver, in a short period of time, the number of pulses emitted by the control system is too much, that is, the high pulse frequency will cause the stepper motor to block up. To deal with this problem, acceleration and deceleration must be adopted. That is to say, when the stepper motor starts, the pulse frequency needs to be gradually increased, and the pulse frequency needs to be gradually reduced when the stepper motor decelerates. This is what we often call "acceleration and deceleration".
The speed of stepper motor is changed according to the change of input pulse signal. In theory, when a pulse is given to the driver, the stepper motor rotates a step angle (subdivision is a step angle). In practice, if the pulse signal changes too fast, the magnetic response between the rotor and the stator will not follow the change of the electric signal due to the damping effect of the internal reverse electromotive force of the stepper motor, which will lead to blockage and loss of step. So when the stepper motor starts at high speed, it is necessary to adopt the method of pulse frequency rising and the process of deceleration when it stops, so as to ensure the fine positioning control of the stepper motor. The principle of acceleration and deceleration is the same. Following are examples of acceleration:
The acceleration process is composed of the base frequency (lower than the direct starting maximum frequency of the stepping motor) and the jump frequency (step-by-step acceleration frequency) to form the acceleration curve (the opposite of the deceleration process). The jump frequency refers to the frequency that the stepper motor progresses step by step in the fundamental frequency. This frequency should not be too large, otherwise it will cause stalling and step loss. Acceleration and deceleration curves are usually exponential curves or modified exponential curves, of course, straight lines or sinusoidal curves can also be used. Acceleration and deceleration control can be completed by using single chip computer or PLC. With regard to different loads and rotational speeds, it is necessary to select the appropriate base frequency and jump frequency so as to achieve the best control effect. Exponential curve, in software programming, first calculate the time constant stored in the computer memory, work point selection. Usually, the acceleration and deceleration time of stepping motor is more than 300 ms. If the acceleration and deceleration time is too short, it is difficult for most stepper motors to complete the high-speed rotation of stepper motors.
The sudden shutdown of the motor is not necessarily blocked. The motor has the highest speed. So does the stepper motor. When the speed exceeds the maximum speed of the stepper motor, the stepper motor will suddenly stop.
The current will affect the torque. The bigger the current is, the bigger the torque is, but the higher the heat of the motor will be. Therefore, the current is generally adjusted to the minimum current under the condition of sufficient torque. If the heat of the motor is still very high in this situation, it needs to change the large torque motor.
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