Views: 13 Author: Site Editor Publish Time: 2023-06-14 Origin: Site
Stepping motor is also called pulse motor, based on the most basic principle of electromagnet, it is a kind of electromagnet that can rotate freely, and its action principle is to rely on the change of air gap permeance to generate electromagnetic torque. Its original model originated between 1830 and 1860. Around 1870, attempts to control were started and applied to the electrode delivery mechanism of hydrogen arc lamps. This is considered the original stepper motor.
A stepper motor is a type of motor that moves in small, precise steps, rather than rotating continuously like a traditional DC motor. It is a type of brushless motor that divides a full rotation into a number of equal steps, typically 200 steps per revolution.
Stepper motors are commonly used in applications that require precise control of motion, such as in robotics, 3D printers, CNC machines, and other industrial machinery. They can rotate in either direction and provide accurate position control without the need for feedback sensors.
Stepper motors can generally be divided into the following three categories:
1. Reactive stepper motor. The stator of the reactive stepper motor is made of silicon steel sheets, and the opposite two magnetic poles are wound with the same winding with different winding directions. When energized, a pair of N and S poles are formed, and there is no winding in the motor rotor. The rotor of the motor is made of soft magnetic material. There are many small teeth with the same size and the same spacing on the outer surface of the rotor pole and the inner surface of the stator pole. Electromagnetic force is the driving force for the reactive stepper motor to move. Under the action of electromagnetic force, the rotor will move to the position of maximum magnetic permeability (or minimum magnetic resistance) and be in a balanced state.
2. Permanent magnet stepper motor. The material of the rotor of the permanent magnet stepper motor is permanent magnetism, the number of poles of the rotor and the stator is the same, the output torque of the motor is large, and the step angle is relatively large, but the working performance is good.
3. Hybrid stepper motor. The structure of the hybrid stepper motor stator is the same as that of the reactive stepper motor. The rotor is divided into two sections in the axial direction. The same number and size of small teeth are evenly distributed in the circumferential direction of the iron core of the two sections, but they are misplaced by half the tooth pitch. A permanent magnet is embedded in the middle of the two iron cores, so that the iron core at one end of the rotor is N pole and the iron core at the other end is S pole, as shown in Figure 1.1. The N and S polarities of the rotor remain unchanged, and the sequential change of the N and S polarities of the stator magnetic poles is realized by controlling the stator winding current, and a corresponding force is generated on the N and S poles of the rotor to push the rotor to rotate as required. Because the permanent magnetic field of the rotor of the hybrid stepper motor also generates part of the torque, it is larger than the torque generated by the stator magnetic field of the reactive stepper motor.
The word "servo" comes from the Greek word "slave". "Servo motor" can be understood as a motor that absolutely obeys the command of the control signal: before the control signal is sent, the rotor stands still; when the control signal is sent, the rotor rotates immediately; when the control signal disappears, the rotor can stop immediately.
The servo motor is a micro motor used as an actuator in an automatic control device. Its function is to convert an electrical signal into an angular displacement or angular velocity of a rotating shaft. Servo motors, also known as executive motors, are used as actuators in automatic control systems to convert received electrical signals into angular displacement or angular velocity output on the motor shaft.
DC servo motors are divided into brushed and brushless motors.
Brushed motors are low in cost, simple in structure, large in starting torque, wide in speed regulation range, easy to control, need maintenance, but easy to maintain (replace carbon brush), generate electromagnetic interference, have requirements for the use environment, and are usually used for cost-sensitive Common industrial and civil occasions.
Brushless motors are small in size and light in weight, high in output and fast in response, high in speed and small in inertia, stable in torque and smooth in rotation, complex in control, intelligent, flexible in electronic commutation mode, can be commutated in square wave or sine wave, maintenance-free motor, high efficiency and energy saving , small electromagnetic radiation, low temperature rise and long life, suitable for various environments.
AC servo motors are also brushless motors, which are divided into synchronous and asynchronous motors. At present, synchronous motors are generally used in motion control. The power range is large, the power can be large, the inertia is large, the maximum speed is low, and the speed increases with the increase of power. Uniform-speed descent, suitable for low-speed and smooth running occasions.
The rotor inside the servo motor is a permanent magnet. The driver controls U/V/W three-phase electricity to form an electromagnetic field. The rotor rotates under the action of this magnetic field. At the same time, the encoder that comes with the motor transmits the feedback signal to the driver. Values are compared to adjust the angle of rotation of the rotor. The accuracy of the servo motor depends on the accuracy of the encoder (number of lines).
The basic structure of an AC servo motor is similar to that of an AC induction motor (asynchronous motor). There are two excitation windings Wf and control windings WcoWf with a phase space displacement of 90° electrical angle on the stator, connected to a constant AC voltage, and using the AC voltage or phase change applied to Wc to achieve the purpose of controlling the operation of the motor.
AC servo motor has the characteristics of stable operation, good controllability, fast response, high sensitivity, and strict non-linearity indicators of mechanical characteristics and adjustment characteristics (required to be less than 10% to 15% and less than 15% to 25% respectively).
