1. Basic definition of servo motors
Servo motors are the core actuators in servo systems. They accurately adjust the motion state of mechanical parts (such as position, speed, and torque) by receiving control signals to achieve high-precision control. Its core function is to convert the input voltage signal into the angular displacement or angular velocity of the shaft, thereby driving the controlled object.
2. Working principle of servo motors
The working principle of servo motors is based on the motor body, driver, and control circuit. The motor body is the actuator for mechanical motion. The driver is responsible for receiving control signals and driving the motor to rotate. The control circuit generates control signals and monitors the running status of the motor. The servo motor controls the speed and position of the motor by receiving control signals. It is usually equipped with an encoder to provide feedback to ensure that the motor can accurately reproduce the position, speed, and torque commands of the host computer.
3. Structural design features of servo motors
1. Rotor design: Servo motors usually use three-phase synchronous motors with unique rotor designs. There are many patches on the rotor, which are usually permanent magnets (such as neodymium iron boron materials). There are two ways to install the permanent magnet of the rotor: surface mount and embedded. The surface mount has a simple structure, low manufacturing cost, and small moment of inertia; while the embedded type performs better at higher speeds and has higher mechanical strength and stability.
2. High efficiency: Since the rotor has its own magnetic field, the servo motor does not need to generate a magnetic field through induced current like an induction motor during operation, so its operating efficiency is higher. In addition, the efficiency of the servo motor can usually reach more than 95%, and it has high continuous torque and effective torque, which is suitable for high load and high dynamic response application scenarios.
3. High precision and fast response: Thanks to the feedback of the encoder and the precise control algorithm, the servo motor can achieve very high position and speed control accuracy with minimal error. It responds to the control signal very quickly, and can complete acceleration, deceleration and commutation in a short time, with excellent dynamic performance.
4. Low torque pulsation: Even if the permanent magnet patches on the rotor of the servo motor are closely attached, there will still be gaps, which will cause certain pulsation. By optimizing the design, this pulsation can be minimized, thereby improving the stability of the motor and the accuracy of the speed.
5. High overload capacity: The servo motor has a high overload capacity in a short period of time, which means a high maximum torque in a wide speed range. For example, some servo motors can support an overload capacity greater than 300% of the rated torque, and the acceleration time is extremely short, such as only 6-10 milliseconds from 0 to 3000 rpm.
4. Maintenance tips for servo motors
1. Regular inspection and maintenance: Regular inspection and maintenance of servo motors is an effective means of preventing failures. The inspection content includes the insulation condition of the winding, the connection status of the lead wire, and the reliability of the grounding system. If problems such as reduced insulation performance or poor wiring are found, they should be handled in time.
2. Moisture-proof measures: For servo motors that are in a humid environment for a long time, moisture-proof measures should be strengthened. For example, dehumidification equipment should be installed around the motor, moisture-proof materials should be used, etc., to reduce the risk of the motor being damp. At the same time, when the motor is stopped, the moisture and dirt on the surface of the motor should be cleaned in time to keep it dry and clean.
3. Improve installation quality: The installation quality of the servo motor directly affects its operating stability and safety. During the installation process, the operating procedures should be strictly followed to ensure that the insulation between the motor and the ground is good, the ground wire is firmly connected, and the grounding resistance meets the specified requirements. After the installation is completed, necessary testing and debugging should also be carried out to ensure the normal operation of the motor.
4. Use high-quality controllers and drivers: The quality of the motor controller and driver directly affects the operating stability and life of the servo motor. Choosing high-quality controllers and drivers can reduce the probability of failure and improve the overall performance of the motor.
5. Parameter adjustment and optimization: Carefully adjust the parameter settings of the servo drive according to the actual application scenario and the performance characteristics of the motor. Reasonably set parameters such as acceleration and deceleration time, speed and torque to avoid overload operation of the motor and ensure that it runs within the comfort zone of the design capacity.
6. Load adjustment and optimization: Thoroughly check the mechanical transmission system and adjust the load to a range that the servo motor can easily withstand. Reduce unreasonable load data to ensure that the robot does not feel difficult during operation and always stays in the comfort zone of the design capacity.
7. Regular maintenance and inspection: In order to avoid servo motor brake failure again, maintenance personnel need to establish a regular inspection system. After each maintenance, the working status of the brake components must be checked in detail, including the wear of the brake pads, the performance of the brake coils, etc. Through regular maintenance and inspection, potential problems can be discovered and solved in time to ensure that the robot can operate stably for a long time.
Source:https://plaza.rakuten.co.jp/stepperonline/diary/202504220000/