Common problems and precautions when using servo drives

Servo driver is a controller used to control servo motors, which is a part of servo systems and mainly used in high-precision positioning systems. It generally controls the servo motor through position, speed, and torque to achieve high-precision positioning of the transmission system. It is an important component of modern motion control and is widely used in industrial robots, CNC machining centers, and other automation equipment.

The servo system includes servo drivers and servo motors. The drivers use precise feedback combined with high-speed digital signal processors (DSP) to control IGBTs to generate accurate current output, which is used to drive three-phase permanent magnet synchronous AC servo motors to achieve precise speed regulation and positioning functions. Poor equipment grounding may cause electric shock, fire, or equipment damage.

1、 The correct shielding grounding point is at the reference potential point inside the circuit, which depends on whether the noise source and receiver are both grounded or floating.
2、 Ensure that the shielding layer is grounded at the same point so that ground current does not flow through the shielding layer.
3、 Avoiding the ground circuit generated by multiple connection methods to the earth can easily be affected by noise and generate currents at different reference points.
4、 Without isolation between the AC power supply and the driver DC bus, non isolated ports or signals of the DC bus cannot be connected to the ground, which may cause equipment damage and personnel injury.
5、 Avoid connecting the servo drive to an external power source, as it will directly affect the operation of the controller and drive.
6、 The common voltage for communication is not connected to the ground, and there may be high voltage between the DC bus and the ground. Direct grounding is prohibited.
7、 In a servo system, the common ground and the earth must be connected together at the signal end.
8、 In order to maintain a constant command reference voltage, the signal ground of the servo driver needs to be connected to the signal ground of the controller.

In many cases, due to the high current and voltage of servo drives, such as some servo drives with a maximum output current of 8A and a voltage of 325V, coupled with the lack of aluminum alloy casing for magnetic shielding, it interferes with the highly sensitive receiver system, making it unable to work, and interferes with the power supply, especially at high frequencies, which may cause the microcontroller and upper computer of the control system to be unable to communicate normally, posing difficulties for normal use. Therefore, the interference problem must be solved.

1、 Install a power filter to reduce pollution to the AC power supply.

2、 A little grounding principle. Connect the ground of the power filter, the PE (ground) of the driver (insulation between the servo driver and the chassis bottom plate), the output lines of the control pulse PULSE - and direction pulse DIR - short circuited, the motor grounding wire, the cable protective sleeve between the drivers, and the driver shielding wire to the grounding column on the chassis wall, and ensure good contact.

3、 Try to increase the distance between the control line, power line, and motor drive line as much as possible to avoid crossing. For example, when handling the installation position of two servo drives in the same chassis in a dual axis drive system, one drive nameplate faces forward and the other faces backward, and these leads are arranged structurally to be as short as possible.
 
4、 Use shielded wires to reduce external interference or interference from oneself (power cord) to the outside world.
Due to the working conditions of the end users of the motion control system and the limitations of the front-line engineering and technical support capabilities of the enterprise, the mechanical and electrical system often cannot be well managed, which can shorten the life cycle of the integrated mechanical and electrical equipment or reduce production capacity due to equipment failures, resulting in economic losses.
 
1、 In order to extend the working life of the servo system, the following issues should be noted during use. For the usage environment of the system, five factors should be considered: temperature, humidity, dust, vibration, and input voltage. Regularly clean the cooling and ventilation system of the CNC device. Regularly check whether the cooling fans on the CNC device are working properly. Depending on the workshop environment, inspections and cleaning should be conducted every six months or once a quarter.

2、 When the temperature inside the CNC device exceeds 55 to 60 ℃ due to high ambient temperature, air conditioning should be installed in a timely manner. Except for maintenance, electrical cabinet doors should be opened as little as possible. Because the dust and metal powder floating in the workshop do not fall on the printed circuit board and electrical connectors, it is easy to cause a decrease in insulation resistance between components, resulting in malfunctions or even component damage.

3、 When CNC machine tools are idle for a long time, regular maintenance and upkeep of the CNC system should also be carried out. Firstly, the CNC system should be powered on frequently and allowed to run without load while the machine tool is locked in place. In the rainy season with high air humidity, electricity should be connected every day to use the heat generated by electrical components to drive away the moisture inside the CNC cabinet, ensuring the stable and reliable performance of electronic components.