Main design principles of stepper motor

1.What is a stepper motor?

A stepper motor is an open-loop control electromechanical actuator that relies on the interaction between an electromagnetic field and a permanent magnet to achieve precise step-by-step rotation. Its core feature is that the rotation angle and speed are strictly proportional to the number and frequency of input electrical pulses: each electrical pulse sent by the driver will drive the motor rotor to rotate by a fixed angle, and the rotation speed is determined by the frequency of the pulse signal.

2.Core working principles of stepper motor

1.Electromagnetic Creation: The stationary part (stator) contains multiple coils of wire arranged in phases. When current flows through a specific coil, it becomes an electromagnet with a defined north and south pole.

2.Rotor Alignment: The moving part (rotor), which contains permanent magnets or soft iron teeth, naturally aligns its poles with the magnetic field generated by the energized stator phase to minimize magnetic resistance (reluctance).

3.Sequential Energizing: By switching the electrical power from one stator phase to the next in a precise sequence, the magnetic field "moves," forcing the rotor to rotate incrementally to maintain alignment.

4.Pulse Control: Each individual pulse sent by a driver corresponds to exactly one step of rotation. The number of pulses determines the total distance traveled, while the frequency of pulses (pulses per second) determines the speed of rotation.         

3.The importance of stepper motor

1.Guarantee High-Precision Positioning in Industrial Automation: In fields such as CNC machine tools, 3D printers, and robotic arms, precise positioning of tools or workpieces is the key to ensuring machining quality. Stepper motors can achieve micron-level positioning precision through step-by-step rotation and subdivision control, avoiding positioning errors caused by continuous rotation of ordinary motors.

2.Enable Adjustable Speed and Stable Operation in Low-Speed Scenarios: Many industrial and medical equipment require stable operation at low speed. Ordinary motors are prone to crawling at low speed, while stepper motors can run stably at low speed with constant torque, ensuring the stability and reliability of equipment operation.

3.Simplify Control System and Reduce Costs: Compared with servo motors that require feedback sensors for closed-loop control, stepper motors can achieve precise positioning in open-loop systems, eliminating the need for expensive feedback components and complex control algorithms.

4.Promote Miniaturization and Intelligence of Equipment: With the development of intelligent equipment, the demand for miniaturized, light-weight precision components is increasing. Stepper motors have the advantages of small size, light weight, and high power density, which can be easily integrated into miniaturized equipment.

5.Ensure Reliability and Long Service Life in Harsh Environments: Stepper motors have a simple structure, few moving parts, and no brushes, which reduces wear and failure probability.

6.Drive Innovation and Development of Emerging Industries: With the rise of emerging industries such as 3D printing, intelligent robots, and unmanned aerial vehicles (UAVs), the demand for stepper motors is increasing, and higher requirements are put forward for their performance.

4.Main design principles of stepper motor

1.Principle of Magnetic Circuit Optimization: The magnetic circuit is the core of the stepper motor’s energy conversion, and optimizing the magnetic circuit design is the key to improving torque, efficiency, and positioning precision. The design should minimize magnetic flux leakage and magnetic resistance.

2.Principle of Step Angle Rational Design: The step angle determines the basic positioning precision of the stepper motor, and its design should be based on the application’s precision requirements and the motor’s structural type.

3.Principle of Torque and Power Matching: The torque and power of the stepper motor should be designed according to the actual load requirements, avoiding blind pursuit of high torque or high power, which will lead to increased size, weight, and cost.

4.Principle of Minimizing Vibration and Noise: Vibration and noise are common problems of stepper motors, which are mainly caused by the discontinuous rotation of the rotor and the electromagnetic force change of the stator.The design should take targeted measures: optimize the tooth shape and tooth pitch of the stator and rotor to reduce the impact of electromagnetic force during step rotation.

5.Principle of Heat Dissipation Optimization: During the working process of the stepper motor, the stator windings will generate heat due to current passing through, and excessive temperature rise will affect the magnetic performance of the core, reduce torque, and even damage the motor.The heat dissipation design should be integrated with the motor structure.

6.Principle of Structural Compactness and Reliability: The structural design of the stepper motor should focus on compactness and reliability, especially for miniaturized application scenarios (such as micro-robots and portable equipment).The overall size should be minimized under the premise of meeting performance requirements.

7.Principle of Compatibility with Control Systems: The stepper motor should be designed to be compatible with common drivers and control systems to improve versatility and applicability. The winding type (two-phase, four-phase) and voltage level should match the output of mainstream drivers.