Direct control of stepper motor PLC
A stepper motor is a digital electromagnetic actuator that converts a pulse signal into an angular displacement. The angular displacement of the stepping motor is proportional to the number of input pulses, and its rotational speed is proportional to the pulse frequency. The steering is related to the phase sequence of the pulse distribution to the phase windings of the stepping motor. Since the stepping motor's rotation angle, rotation speed and steering can be controlled by digital (pulse), stepping motors are widely used in the field of digital servo.
Method for directly controlling stepping motor by PLC
This paper presents a method for directly controlling a stepper motor with a programmable controller (PLC), as shown in Figure 2. The advantage of this technical route is that the workload of the system design is greatly reduced, there is no matching problem of the interface signals of various parts, and the reliability of the system is improved. The entire control system consists of a PLC and a stepper motor. As an industrial control computer PLC, the function is getting stronger and stronger. Not only for switching logic control, but also for closed-loop process control, and can be combined with other computers to form a multi-level control system. With the support of the powerful functions of PLC, the tasks of different command pulse controllers of various control systems can be completed by different control programs of PLC. For the function of the ring pulse distributor and power amplifier, two characteristic requirements are imposed on the PLC. First, the PLC used in this application is preferably a PLC with real-time refresh technology, so that the frequency of the output signal can reach several thousand Hz or higher. The purpose is to enable the ring pulse distribution to have a higher distribution speed, fully utilize the speed response capability of the stepping motor, and improve the rapidity of the entire system. Second, the output port of the PLC itself should use high-power transistors to meet the driving requirements of tens of volts pulse voltage and several ampere pulse current of each phase winding of the stepping motor. It should be pointed out that PLC with relay or thyristor as output port, even if the software ring pulse distribution can achieve high speed requirements, but because the output port device is difficult to turn on and off the DC power at high speed, it can not provide the phase winding of the stepper motor. The pulse current is driven, so it cannot be used for PLC direct control of stepper motors. For PLCs that meet the requirements of one or two, such as the IP1612DC-220 programmable controller of US IPM, direct control of the stepper motor can be performed.
