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Working principle of servo driver

September 09,2022

At present, the mainstream servo drivers all use digital signal processor (DSP) as the control core, which can realize complex control algorithms, digitalization, networking and intelligence. The drive circuit designed with intelligent power module (IPM) as the core is widely used in power devices. IPM integrates the drive circuit, and has fault detection and protection circuits such as over-voltage, over-current, over-temperature and under-voltage. A soft start circuit is also added to the main circuit to reduce the impact of the start-up process on the driver.

The power unit first rectifies the input three-phase electricity or commercial power through the three-phase full-bridge rectifier circuit to obtain the corresponding direct current. After the rectified three-phase electricity or commercial power, the three-phase permanent magnet synchronous AC servo motor is driven by the frequency conversion of the three-phase sinusoidal PWM voltage source inverter. The whole process of the power drive unit can be simply described as the process of AC-DC-AC. The main topology circuit of AC-DC rectifier unit is three-phase full-bridge uncontrolled rectifier circuit.
With the large-scale application of servo system, servo driver usage, servo driver debugging and servo driver maintenance are all important technical topics of servo driver nowadays. More and more industrial control technical service providers have made deep technical research on servo driver.

Servo is an important part of modern motion control, which is widely used in industrial robots and CNC machining centers. Especially the servo driver used to control AC permanent magnet synchronous motor has become a research hotspot at home and abroad. At present, the closed-loop control algorithm of current, speed and position based on vector control is widely used in the design of AC servo driver. Whether the speed closed-loop design in this algorithm is reasonable or not plays a key role in the whole servo control system, especially in the performance of speed control.

Requirements of servo feed system

1. Wide speed regulation range
2, the positioning accuracy is high
3. Sufficient transmission rigidity and high speed stability.
4. Quick response, no overshoot.
In order to ensure productivity and processing quality, besides high positioning accuracy, it is also required to have good fast response characteristics, that is, fast response to tracking command signals, because the acceleration and deceleration of the numerical control system are required to be large enough when starting and braking, so as to shorten the transition time of the feed system and reduce the contour transition error.
5. Low speed, high torque and strong overload capacity.
Generally speaking, the servo driver has an overload capacity of more than 1.5 times in a few minutes or even half an hour, and can overload 4 ~ 6 times in a short time without damage.

6. High reliability.
The feed drive system of CNC machine tools is required to have high reliability, good working stability, strong adaptability to temperature, humidity, vibration and other environments and strong anti-interference ability.

Requirements for motors

1. The motor can run smoothly from the lowest speed to the highest speed, and the torque fluctuation is small, especially at low speed, such as 0.1r/min or lower, and there is still a steady speed without crawling.
2. The motor should have a large overload capacity for a long time to meet the requirements of low speed and high torque. Generally, DC servo motors are required to overload 4 ~ 6 times in a few minutes without damage.
3. In order to meet the requirements of quick response, the motor should have a small moment of inertia and a large locked-rotor torque, as well as a minimum time constant and starting voltage.
4. The motor should be able to withstand frequent startup, braking and reverse rotation.
In addition, we have other products, such as stepper motor ,linear actuator,ball screw,cross roller guide,etc.If you need to contact the manufacturer.