A servo driver is a controller used to control servo motors, which functions similarly to a frequency converter acting on a regular AC motor. It is part of a servo system and is mainly used in high-precision positioning systems.
Servo drives are an important component of modern motion control and are widely used in automation equipment such as industrial robots and CNC machining centers. Generally, servos have three control modes: position control mode, torque control mode, and speed control mode.
|
|
|
1. Position control
The position control mode is generally determined by the frequency of external input pulses to determine the speed of rotation, and by the number of pulses to determine the angle of rotation. Some servos can also directly assign values to speed and displacement through communication. As the position mode can have strict control over both speed and position, it is generally applied to positioning devices.
2. Torque control
The torque control method is to set the output torque of the motor shaft to the outside through external analog input or direct address assignment. The set torque can be changed by instantly changing the analog setting, or by changing the corresponding address value through communication.
The application is mainly in winding and unwinding devices that have strict requirements for the material, such as winding devices or fiber optic equipment. The torque setting should be changed at any time according to the change of the winding radius to ensure that the material's stress does not change with the change of the winding radius.
3. Speed mode
The rotation speed can be controlled through analog input or pulse frequency. In the outer loop PID control with upper control device, the speed mode can also be positioned, but the position signal of the motor or the position signal of the direct load must be fed back to the upper control for calculation. The position mode also supports direct load outer ring detection of position signals. At this time, the encoder at the motor shaft end only detects the motor speed, and the position signal is provided by the direct detection device at the final load end. The advantage of this is that it can reduce errors in the intermediate transmission process and increase the positioning accuracy of the entire system.
If there are no requirements for the speed and position of the motor, as long as a constant torque is output, of course, torque mode is used.
If there are certain precision requirements for position and speed, but real-time torque is not very concerned, it is not convenient to use torque mode. It is better to use speed or position mode.
If the upper controller has good closed-loop control function, the speed control effect will be better. If the requirements are not very high or there is basically no real-time requirement, the position control method should be adopted.
Servo drives, also known as "servo controllers" or "servo amplifiers", are a type of controller used to control servo motors. Their function is similar to that of a frequency converter acting on a regular AC motor, and they are part of a servo system. They are mainly used in high-precision positioning systems. Generally, servo motors are controlled through three methods: position, speed, and torque to achieve high-precision positioning of the transmission system. Currently, it is a high-end product in transmission technology.
Servo drives are an important component of modern motion control and are widely used in automation equipment such as industrial robots and CNC machining centers. Especially for servo drives used to control AC permanent magnet synchronous motors, they have become a research hotspot both domestically and internationally. The current design of communication servo drives commonly adopts a current, velocity, and position closed-loop control algorithm based on vector control. The rationality of the speed closed-loop design in this algorithm plays a crucial role in the performance of the entire servo control system, especially in terms of speed control.
The real-time speed measurement accuracy of the motor rotor is crucial for improving the dynamic and static characteristics of the speed control in the servo drive speed loop. To seek a balance between measurement accuracy and system cost, incremental photoelectric encoders are generally used as speed sensors, and the corresponding commonly used speed measurement method is the M/T speed measurement method. Although the M/T speed measurement method has a certain measurement accuracy and a wide measurement range, it has inherent defects, mainly including:
1. At least one complete code wheel pulse must be detected during the speed measurement cycle, which limits the minimum measurable speed;
2. The timer switches of the two control systems used for speed measurement are difficult to strictly maintain synchronization, and the accuracy of speed measurement cannot be guaranteed in measurement scenarios with large speed changes. Therefore, the traditional speed loop design scheme using this speed measurement method is difficult to improve the speed tracking and control performance of servo drives
Currently, mainstream servo drives use digital signal processors (DSPs) as the control core, which can implement complex control algorithms, achieve digitization, networking, and intelligence. Power devices commonly use drive circuits designed with intelligent power modules (IPMs) as the core. IPMs integrate drive circuits internally and have fault detection and protection circuits for overvoltage, overcurrent, overheating, undervoltage, etc. Soft start circuits are also added to the main circuit to reduce the impact of the start-up process on the driver. The power drive unit first rectifies the input three-phase power or mains power through a three-phase full bridge rectifier circuit to obtain the corresponding DC power. After rectification, the three-phase power or mains power is used to drive the three-phase permanent magnet synchronous AC servo motor through a three-phase sine PWM voltage type inverter frequency conversion. The entire process of the power drive unit can be simply described as the AC-DC-AC process. The main topology circuit of the rectifier unit (AC-DC) is a three-phase full bridge uncontrolled rectifier circuit.
With the large-scale application of servo systems, the use, debugging, and maintenance of servo drives are important technical issues for servo drives today. More and more industrial control technology service providers have conducted in-depth technical research on servo drives.
Servo drives are an important component of modern motion control and are widely used in automation equipment such as industrial robots and CNC machining centers. Especially for servo drives used to control AC permanent magnet synchronous motors, they have become a research hotspot both domestically and internationally. The current design of communication servo drives commonly adopts a current, velocity, and position closed-loop control algorithm based on vector control. The rationality of the speed closed-loop design in this algorithm plays a crucial role in the performance of the entire servo control system, especially in terms of speed control.