Working principle of servo drive

With the emergence of fully digital AC servo systems, AC servo motors are increasingly used in digital control systems. In order to adapt to the development trend of digital control, most motion control systems use fully digital AC servo motors as actuator motors. The control method is implemented using pulse trains and direction signals.

Generally, servos have three control modes: speed control, torque control, and position control.

At present, mainstream servo drives all use digital signal processors (DSP) as the control core, which can realize relatively complex control algorithms and achieve digitization, networking and intelligence. Power devices generally use drive circuits designed with intelligent power modules (IPM) as the core. The IPM integrates the drive circuit internally and has fault detection and protection circuits such as overvoltage, overcurrent, overheating, and undervoltage. A soft start circuit is also added to the main circuit to reduce the impact of the start-up process on the drive.

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 direct current. After the rectified three-phase power or mains power, the three-phase permanent magnet synchronous AC servo motor is driven by a three-phase sinusoidal PWM voltage inverter. The entire process of the power drive unit can be simply described as an 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, servo drive use, servo drive debugging, and servo drive maintenance are all relatively important technical topics 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 part of modern motion control and are widely used in automation equipment such as industrial robots and CNC machining centers. In particular, servo drives used to control AC permanent magnet synchronous motors have become a research hotspot at home and abroad. The current AC servo drive design generally adopts a three-loop control algorithm based on vector control: current, speed, and position. Whether the speed closed-loop design in this algorithm is reasonable or not plays a key role in the entire servo control system, especially the speed control performance.

What is the working principle of the servo motor drive with reducer?

Servo drives, also known as "servo controllers" or "servo amplifiers", are controllers used to control servo motors. They function similarly to frequency converters acting on ordinary AC motors. They are part of the servo system and are mainly used in high-precision positioning systems. Generally, servo motors are controlled in three ways: position, speed, and torque to achieve high-precision transmission system positioning. They are currently high-end products in transmission technology.

Servo drive block diagram

Figure 1 Principle block diagram of servo drive

Working principle of servo drive

First, the power drive unit rectifies the input three-phase power or mains power through a three-phase full-bridge rectifier circuit to obtain the corresponding direct current. After the rectified three-phase power or mains power, the three-phase sinusoidal PWM voltage inverter is used to drive the AC servo motor. The entire process of the power drive unit can be simply described as an AC-DC-AC process. The main topology circuit of the rectifier unit (AC-DC) is a three-phase full-bridge uncontrolled rectifier circuit.