1. What is stepper motor?
Stepper motor is a type of motor that uses electricity but has a very different principle and application compared to conventional 1-phase and 3-phase electric motors.
In essence, this is a type of synchronous motor, capable of transforming the control signals of machines in the form of discrete electrical pulses emitted in succession, forming rotational movements. Sometimes it is the movements of the rotor, which help the user to fix the machine’s rotor into the required position.
In general, a stepper motor (stepper motor) is a type of motor that you can specify its rotational frequency. The smaller its step angle, the greater the number of steps per revolution of the motor and the greater the accuracy of the position we obtain.
The step angles of the motor can reach a maximum of 90 degrees and a minimum of 0.72 degrees. However, the most commonly used motor stepping angles are 1.8 degrees, 2.5 degrees, 7.5 degrees, and 15 degrees.
2. Classification of stepper motor
+ Classification based on the number of phases of the motor
- 2-phase stepper motor will correspond to a step angle of about 1.8 degrees.
- 3-phase stepper motor will correspond to a step angle of about 1.2 degrees.
- 5-phase stepper motor will correspond to a step angle of about 0.72 degrees.
+ Classification of stepper motors based on rotor
- Stepper motors with rotors made of winding or permanent magnets.
- Stepper motor changes reluctance. This is a type of motor whose rotor is not actuated but has an induction element.
+ Classification depending on motor polarity
- Unipolar stepper motor.
- Bipolar stepper motor.
3. Stepper motor construction
The structure of stepper motor consists of: rotor and stator
+ The rotor is actually a series of permanent magnets, which are carefully stacked on top of each other. These magnets are divided into pairs of poles arranged symmetrically
+ The stator is made of ferromagnetic, they are divided into small grooves to place the windings
4. Working principle of stepper motor
The operating principle of the stepper motor does not rotate according to the usual mechanisms, because the step motor rotates in steps, so it has a high accuracy, especially in terms of cybernetics.
Stepper motors work thanks to the operation of electronic switches. These electronic circuits will put the signals of the control command running into the stator in sequential numbers and a certain frequency.
The total number of rotations of each rotor corresponds to the number of times the motor is switched. At the same time, the rotation direction and rotation speed of the rotor also depend on the conversion sequence number as well as its switching frequency.
Currently, there are 4 methods to control the most commonly used stepper motor, which are:
- Waveform (Wave) stepper motor control: This is a control method that provides pulses to the controller, operating in turn in a certain order for each phase winding.
- Full step motor control: This is a method of controlling pulse supply at the same time, and both phase windings are arranged in succession.
- Half step motor control: It is a control method that combines both waveform motor control and full stepper motor control. When controlling the motor according to this method, the value of the step angle is less than 2 times and the number of steps of the stepper motor will also increase 2 times compared to the control method with a sufficient stepper motor. However, this control method has an extremely complicated control pulse generator.
- Microstep motor control (Microstep): This is a new method, applied only during stepper motor control. From there, allow the stepper motor to stop and position within the middle half-step position between the two sufficient steps.
5. Advantages and disadvantages of stepper motors
+ Advantage:
- The first advantage of the Step Motor is its ability to provide extremely high torque, especially in the low and medium speed ranges.
- The product is durable, the product price is also relatively low, so buying and selling is also quite convenient, without any obstacles. Not only that, it is also relatively easy to replace the stepper motor during production.
+ Disadvantages
- Stepping Motor often occurs unpleasant phenomena, such as slipping. The known reason is that the magnetic force is weak or sometimes the power supply to the motor is not enough.
- During operation, the Stepping Motor often makes an annoying noise and the motor gradually heats up. With the new generation of Stepping Motor motors, the noise and heat of the motor have been significantly reduced.
- The Step Motor should not be used for machinery that requires high speed.
6. Application of stepper motor
Stepper motors are now being used a lot and are increasingly popular, mainly in digital motion control of motors. It is performed by commands that are automatically encoded as numbers.
The application of stepper motors in the automation industry, especially for mechanical equipment, requires precision. For example, modern industrial machines help to serve the mechanical processing process such as: CNC plasma cutting machines, CNC laser cutting machines…
In addition, in the field of computer technology, stepper motors are also used in hard drives or floppy drives, even printers…
In the field of security, stepper motor is a new surveillance product, bringing outstanding progress to the security industry.
In the medical field, stepper motors are used to manufacture medical scanners, samplers, and even inside digital dental imaging machines, liquid pumps, respirators, and other devices. blood sample analyzer.
In the consumer electronics sector, stepper motors are used in the camera’s manufacturing process, providing sharp and precise focus to the camera, while also providing automatic zooming of digital cameras. motion or 3D printers.
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