What is the working principle of the servo motor driver for the WPWDKV70,WPWDKV80,WPWDKV100,WPWDKV120,WPWDKV135 gearbox?
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 ordinary AC motors, and they are part of servo systems. 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.
Principle block diagram of servo drive
Figure 1 Principle Block Diagram of Servo Driver
2、 Servo driver structure
The servo drives all use digital signal processors (DSP) as the control core, which can achieve complex control algorithms, digitization, networking, and intelligence. Power devices generally use driving circuits designed with intelligent power modules (IPM) as the core. The IPM integrates driving circuits inside and also has 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 process on the driver.
3、 Working principle of servo drive
Firstly, the power drive unit rectifies the input three-phase or mains electricity through a three-phase full bridge rectifier circuit to obtain the corresponding DC power. After rectification, the three-phase or mains power is used to drive the AC servo motor through a three-phase sine PWM voltage source inverter for frequency conversion. The entire process of the power drive unit can be simply described as the AC-DC-AC process, and the main topology circuit of the rectifier unit (AC-DC) is a three-phase full bridge uncontrolled rectifier circuit.
4、 Servo driver control mode
There are generally three control methods for servo systems: position control, torque control, and speed control.
1. Position control: The position control mode is generally determined by the frequency of external input pulses to determine the rotational speed, and the rotation angle is determined by the number of pulses. Some servos can also directly assign values to speed and displacement through communication. Due to the strict control of speed and position, the position mode is generally applied to positioning devices.
2. Torque control: The torque control method is to set the output torque size of the motor shaft to the outside through the input of external analog signals or direct address assignment. The set torque size can be changed by changing the analog signal setting in real time, or by changing the corresponding address value through communication.
The application is mainly in winding and unwinding devices with strict requirements for materials, such as wire winding devices or fiber pulling equipment. The torque setting should be changed at any time according to the change of the winding radius to ensure that the force on the material will not change with the change of the winding radius.
3. Speed mode: The rotational speed can be controlled through the input of analog signals or the frequency of pulses. In the outer loop PID control with an 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 loop for calculation.
