Structural advantages and common applications of permanent magnet stepper motors

1. Basic introduction to permanent magnet stepper motors

Permanent magnet stepper motors are devices that convert electrical energy into mechanical energy. Their core feature is that the rotor uses permanent magnets, which can generate a magnetic field with alternating polarity in the air gap. When the stator winding is energized, the rotor will align with the direction of the magnetic field determined by the phase winding. When the winding is switched, the rotor will rotate a specific angle to achieve stepping motion.

2. Working principle of permanent magnet stepper motors

The working principle of permanent magnet stepper motors is based on the principle of electromagnetism. Its internal structure includes a fixed part (stator) and a movable part (rotor). The stator has a gear-like protrusion with a coil wound on it, and the rotor is a permanent magnet. When the stator phase is energized, the current passing through the coil generates a magnetic field, and the rotor will align with the magnetic field. By applying voltage to different phases in turn, the rotor will rotate a specific angle and eventually reach the required position.

3. Structural advantages of permanent magnet stepper motors

‌1. High efficiency‌: One of the biggest advantages of permanent magnet stepper motors is their high efficiency. Because it uses high-performance permanent magnetic materials, it does not require an external power supply to provide a magnetic field, which reduces energy loss, so the efficiency can reach more than 90%, which is significantly higher than traditional motors.

2. Excellent power density: Permanent magnet stepper motors have higher output power at the same volume and weight. This feature makes it particularly outstanding in application environments with limited space, such as electric vehicles, robots, and portable devices. High power density not only improves the performance of the equipment, but also helps to reduce the weight of the equipment, which is conducive to the portability and flexibility of the product.

3. Wide operating range: Permanent magnet stepper motors have a wide operating range and can work stably under various working conditions. Because its starting and running torque is relatively constant, it can still maintain good performance even at low speeds and high loads. This is particularly important in application scenarios that require frequent starting and stopping, such as elevators, lifts, etc.

4. Low maintenance cost: Compared with traditional motors, permanent magnet stepper motors have less mechanical wear. Its brushless design eliminates the wear and replacement of carbon brushes, greatly reducing maintenance costs. This low maintenance requirement enables permanent magnet stepper motors to maintain high reliability in long-term operation and reduce downtime.

‌5. High precision and repeatability: Permanent magnet linear stepper motors can achieve high-precision linear motion through precise linear motion control technology and efficient drive algorithms. Feedback systems such as grating scales or encoders provide real-time position information to the motor, and the drive algorithm adjusts the current and voltage based on this information to ensure the accuracy of the stepping action.

4. Common applications of permanent magnet stepper motors

1. Industrial automation and control: In CNC machine tools (CNC), permanent magnet stepper motors are used to drive the X, Y, and Z axes of lathes, milling machines, and engraving machines for precise linear or rotational motion, and control tool position and feed speed. In addition, they are also used in 3D printers to accurately control the movement of the print head and platform to achieve layer-by-layer material stacking.

‌2. Medical and laboratory equipment‌: In the medical field, permanent magnet stepper motors are used to control the rotation and positioning of the scanning head of CT/X-ray machines, adjust the precise position of certain components in nuclear magnetic resonance, and control the propulsion speed and distance of the piston in the infusion pump/syringe pump to achieve trace and uniform delivery of liquid medicine‌. In laboratory equipment, they are also used in DNA sequencers and automated sample processors to accurately move the position of sample trays and detection probes‌.

‌3. Office automation equipment‌: In printers, scanners, copiers and fax machines, permanent magnet stepper motors are used to control the precise movement of print heads, scanning heads and paper‌

1. In addition, they are also used in plotters to accurately control the movement of drawing pens or knives and draw fine graphics‌.

4‌. Consumer electronics and household appliances‌: In cameras, smart door locks and air conditioners, permanent magnet stepper motors are used to control the translation, pitch and rotation of cameras, the electronic unlocking of smart door locks, and the swing of air guide plates of air conditioners‌.

5. Other applications: Permanent magnet stepper motors are also used in stage lighting to control the angle and zoom of spotlights, as well as in instrumentation and control to rotate car dashboard pointers and adjust valve openings.

Source:https://plaza.rakuten.co.jp/yixing/diary/202506250000/

Main control methods and maintenance tips for servo motors

1. Basic definition of servo motors

A servo motor is an actuator motor used to precisely control the movement of mechanical components in a servo system. It can convert electrical signals into angular displacement or angular velocity, and has the characteristics of high precision, fast response and high stability. It achieves precise adjustment of position, speed and torque through a closed-loop control system, and is widely used in automation equipment, robots, CNC machine tools and other fields. ‌‌

2. Working steps of servo motors

1. Control signal reception: The controller (such as PLC, motion controller or microprocessor) generates a control signal according to a preset control algorithm, representing the desired motor position, speed or torque.

‌2. Precision control: After receiving the control signal, the servo drive adjusts the power supply to the motor to ensure that the actual motion state of the motor is consistent with the requirements of the control signal, involving complex current, voltage regulation and pulse width modulation (PWM) technology.

‌3. Feedback mechanism: The built-in or external encoder monitors the actual position, speed and/or torque of the motor in real time, and feeds this information back to the drive and even the controller.

‌4. Closed-loop control‌: The driver compares the actual feedback value with the target value of the control signal, calculates the deviation and adjusts the motor's drive current accordingly to achieve closed-loop control, ensuring that the servo motor can respond to the control command quickly and accurately, and achieve high-precision positioning and dynamic performance‌.

3. Main control methods of servo motors

1. Amplitude control ‌: By changing the amplitude of the control voltage, keeping the frequency and phase unchanged, the speed and torque of the motor are adjusted. In essence, the output is controlled by adjusting the voltage amplitude to affect the magnetic field strength.

2. Phase control ‌: Keep the control voltage amplitude and frequency unchanged, only change the phase difference, and affect the rotation direction of the magnetic field or the size of the synthetic magnetic field through phase changes, thereby adjusting the motor's operating state‌.

3. Amplitude-phase control ‌: Simultaneously adjust the amplitude and phase of the control voltage, comprehensively adjust the magnetic field characteristics, and achieve precise control of the motor‌.

4. Speed ​​control , position control and torque control ‌: These are the three most common control methods for servo motors. Speed ​​control is used to adjust the speed of the motor; position control is used to accurately control the position of the motor; torque control is used to adjust the output torque of the motor.

5. Fuzzy control: The motor parameters are self-learned through fuzzy logic algorithms to improve the stability and response accuracy of the motor under different loads and operating conditions. This method obtains the correlation information between the motor structure and load changes by jointly sampling and eliminating interference from multi-source operating data in the industrial site.

6. PID control: In complex environments, the three-loop superposition PID control logic of the current loop, speed loop and position loop is used to optimize the pointing stability and communication performance of the motor. This method can effectively overcome the limitations of the single-loop PID control of stepper motors and ensure the stable pointing and communication performance of the motor in various complex environments.

4. Servo motor maintenance tips

1. Regular inspection and maintenance: Regularly check the various components of the servo motor, including encoders, bearings, gears, etc., to ensure that they are firmly connected and well lubricated. Clean the dust and dirt on the surface of the motor to keep the motor clean.

‌2. Avoid overload operation‌: Match the rated load and speed of the motor reasonably to avoid overload operation. Check the maximum radial load force of the motor, improve the mechanical design, and ensure that the motor runs under a reasonable load‌.

‌3. Pay attention to heat dissipation issues‌: Ensure that there is enough ventilation space around the motor to avoid overheating of the motor. Clean the air duct and take cooling measures to ensure that the motor runs at a suitable temperature‌.

‌4. Reasonably control the operating environment‌: Ensure that the temperature, humidity, dust and other factors of the motor operating environment are within a reasonable range. In high temperature, high humidity or dusty environments, the heat dissipation and cleaning of the motor should be strengthened‌.

‌5. Check the connection wire regularly‌: Check whether the motor connection wire is loose or damaged to ensure a firm connection. Check whether the motor grounding wire is reliably grounded to ensure the safe operation of the motor‌.

‌6. Check the lubrication condition regularly‌: Regularly check the lubrication condition of the bearings and gears of the servo motor, and add or replace the lubricating oil in time to ensure the smooth operation of the motor‌.

‌7. Follow the operating procedures‌: When operating the servo motor, the operating procedures and safety specifications of the equipment should be followed to avoid improper operations such as frequent starting, stopping or overspeeding to reduce impact and wear on the motor‌.

Source:https://plaza.rakuten.co.jp/yixing/diary/202506040000/