Application of industrial UPS in automobile welding robot anti electric shock (1/3)

The most widely used robot in the industrial manufacturing field is welding robot. In particular, in the automobile manufacturing industry, the use of robots accounts for about 30% of the total industrial robots, and the number of welding robots accounts for about 60%.

For the imported original welding robot, the manufacturer added a regulated power supply in front of the input terminal of the controller. However, this measure obviously has serious deficiencies. Only industrial UPS can perfectly solve the power problem, especially the voltage sag commonly seen in the industrial field, namely "power swing".

The traditional manual welding has the disadvantages of large amount of labor, high labor cost and bad working environment. The welding accuracy is affected by the quality of workers and the efficiency is low. It can not meet the requirements of quality and output of modern high-tech products. Therefore, to ensure the stability of welding product quality, improve productivity and improve labor conditions have become the problems to be solved urgently in the development of modern welding manufacturing technology, thus the welding robot in the field of industrial manufacturing emerges as the times require. At present, the welding robot is the most widely used robot in the industrial manufacturing field. Especially in the automobile manufacturing industry, the robot usage accounts for about 30% of the total industrial robots, and the number of welding robots accounts for about 60%. The production process of automobile welding robot is complex, there are many interlocking devices, and various detection signals affect each other. If any robot in the production line stops due to electrical fault, the operation of the whole production line will be affected.

In 2015, a famous automobile manufacturer, in its newly started welding branch, had frequent failures of welding robots on the production line. The reason is that the voltage sag caused by the large number of servo motors of dozens of welding robots can not be solved by adding a regulated power supply in front of the controller input terminal when the imported industrial robot manufacturer is in complete set.

In Figure 1, the main task of the industrial robot controller is to control the robot's motion position, posture and trajectory, operation sequence and action time in the workspace. The degree of freedom of a robot depends on the number of joints it can move. The more the number of joints, the higher the degree of freedom, the better the displacement accuracy, and the more servo motors need to be used; in other words, the more precise the industrial robot, the more servo motors there are. There are three types of servo motor:

1. Hydraulic and pneumatic drive: slow response speed and low precision. With the improvement of response speed and control accuracy requirements of welding robot servo drive system, hydraulic and pneumatic drive are gradually withdrawn from the market;

2. DC Motor Service: DC servo has the advantages of high precision and simple control system, which is the mainstream of current servo system. However, there is a brush mechanical reversing mechanism, which may cause harm to the safety of the work site. At the same time, the mechanical reversing mechanism is easy to wear, which is not conducive to the continuous and reliable work of the servo system, and the maintenance is difficult;

3. AC permanent magnet synchronous motor servo: small mass power ratio, no mechanical reversing mechanism, easy to maintain, but the control system is more complex, not easy to achieve high-precision control. With the development of technology, AC synchronous motor gradually has good technical performance, such as wide speed range, high speed stability precision, fast dynamic response and four quadrant operation, and is gradually replacing DC motor.

Each multi axis robot is controlled by a set of control system, which means that the performance of the controller is required to be high. Once the controller misoperation, shutdown or even data loss occurs due to power problems (power failure, surge, overvoltage, low voltage, etc.), it will lead to a major accident. After analyzing the failure of the power supply added in front of the controller's input terminal, it is found that 98% of the failure of the regulated power supply can not work normally, which is caused by voltage sag, i.e. "power swing". The configuration of regulated power supply has inherent defects, so industrial UPS should be selected.

(From magazine UPS Application - November 7 2017)

About AVIC-Tech

AVIC-Tech (Xiamen)Electric Power Technology Co.,Ltd is a high-tech enterprise specializing in R&D, manufacture, sales and service of high-end power supply. Our flagship products are industrial UPS (1kVA-800kVA), dynamic voltage restorer (10kVA-3150kVA), and lithium battery system, which are widely used in nuclear power, electric power, petroleum and petrochemical, rail transportation, industrial manufacturing and other fields.

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