Current situation and development trend of welding power supply testing equipment
According to the welding process of welding energy generated by the basic characteristics of various welding methods will be summarized into five categories, namely, arc welding, resistance welding, special welding, gas welding and brazing. Different types of welding equipment have different detection methods and testing equipment, welding power supply mechanical and electrical performance test items and the emphasis is also different. Arc welding and resistance welding is currently the most widely used welding method. Arc and resistance welding welding power supply testing equipment is also the most commonly used two major categories of power testing equipment.
1 resistance welding power supply testing equipment
The traditional resistance welding power source testing equipment is mainly a large current tester, which generally only detects the size of the welding current and the length of the power-on time. The detected welding current is only divided into the alternating current and the secondary rectified direct current. With the development of electronics and computer technology, new forms of resistance welding power sources such as inverting DC, AC, square wave pulse and capacitive energy storage emerge in an endless stream. The welding current of this type of power source has non-sinusoidal and non-periodic welding current, In addition to testing the electrical performance parameters of the welder, the electrode pressure, the displacement of the electrode in the welding process (reflecting the welding quality parameters), the cooling water flow and other parameters are required to be tested, and the test results are formed The report, the traditional testing equipment has been unable to meet these test requirements.
In recent years, Japan, Germany and other developed countries have introduced a multi-functional resistance welding test equipment that can be connected with industrial control computer information, set welding quality control and testing. Such as the Japanese MIYACHI MM-360A resistance welding tester can measure the welding pressure and current welding process, and display the waveform, but also with the computer to process the measured data; MM-730A resistance welding tester through Anti-magnetic interference displacement sensor, the welding electrode displacement monitoring, and then indirectly control the formation of welding nuggets. Germany Boschrexroth inverter resistance welding and precision control technology has been widely used in industrial production systems.
Boschrexroth is arguably the world's largest manufacturer of medium frequency resistance welding systems. Its "Multifunction IF Controller PSI63S" (resistance welding constant power control technology and ultrasonic control technology) is no longer a conventional IF controller but integrated Universal IF controller, welding monitoring controller (constant power control technology and ultrasonic control technology) and servo motion controller (pneumatic components or electronic motor) universal controller, it can be welding current, welding time, welding power, welding Nuclear size, welding location, welding displacement, welding pressure and other parameters of the full closed-loop control. The welding controller that controls all the welding parameters in real time and tests simultaneously is the development direction of the resistance welding control and monitoring system.
2 arc welding power detection equipment
As with the development of resistance welding test equipment, arc welding power supply testing equipment has also gone through different stages of development. With its technical content and characteristics, it is divided into four stages of development. In our arc welding test equipment, the most representative arc welding power supply testing equipment is based on Chengdu Welding Machine Research Institute, National Welding Machine Testing Center (Chengdu Electrical Inspection), Chengdu Tripartite Electric Co., Ltd. mainly developed test bench .
a) The first generation of testing equipment to Chengdu Institute of Welding HHC series of arc welding power supply test stand as the representative, with the traditional transformer, shunt for the current sensing of the original, together with the pointer current, voltage, power stage Table, the welding power supply current, voltage, power measurements, with the contactor switch and change the size of non-inductive resistance load to simulate the arc. At present, this type of testing equipment is still used in some welding power plants. It has the characteristics of high precision and good reliability and stability. However, it is difficult to meet the requirements of modern high-efficiency Production test.
b) The second-generation testing equipment takes digital TDC series power supply test bed researched and produced by Chengdu Electric Inspector Institute and Chengdu Sifang Electric Co., Ltd. as representative, replaces the pointer type table with digital meter, Hall current sensor replaces mutual inductor and shunt , The same in terms of function and test accuracy with the first generation of equipment, but the volume significantly reduced, the use and maintainability has been greatly improved, intuitive readings, easy to operate, by the majority of the country's welding power production enterprises widely used, But it still carries the drawbacks of the first generation of equipment.
c) The development of modern manufacturing technology and welding production, the continuous improvement of the testing requirements, the real-time quality and the testing accuracy of the welding equipment testing make the structure and function of the traditional testing equipment increasingly prominent and difficult to meet and satisfy High efficiency, informatization of modern testing needs. The third generation of testing equipment is a new generation of PTE series information released by Chengdu Sanfang Electric Co., Ltd. on the basis of the prototype of "Smart AC / DC Power Supply Test System" Detection system is a typical representative. It virtual instrument technology as the implementation platform, with a large amount of information, detection speed, excellent man-machine interface, high precision, flexibility and other advantages, but also achieved on the arc welding power harmonic current analysis, power factor and efficiency Real-time measurement of important parameters.
The detection system in the structure has the following characteristics:
(1) using virtual instrument technology as the implementation platform. Host selection NI PXI-8174 embedded controller, PXI-6071E multi-function card data acquisition using PXI interface, load control using PLC as the main control unit. The host-side program is event-driven.
(2) The distributed (DCS) control method is used to decompose a large system with many state variables into several independent modules. The configuration and expansion of the system are very convenient. The centralized management and decentralized control effectively enhance the automatic test System flexibility.
(3) The software environment, the use of common Windows 2000 operating system, help to make full use of existing software resources, programming environment is LabVIEW, and is divided into front panel and source code. WYSIWYG front panel technology constitutes the main interface of the program.
The detection system integrates a variety of computer and information technology advantages, can quickly and easily complete the welding power of the electrical parameters of the factory inspection, and can visually see the details of each waveform was measured to help better understanding and awareness The physical meaning of the amount of detection, the function has the following characteristics:
(1) intelligent programmed load adjustment. According to the type of welder input by the user, when the load needs to be adjusted, the main system will automatically send a command to the PLC. The PLC will determine the state of its output contact according to the command, so as to control the non-inductive load resistance and control the contactor on and off, the goal of. The whole process has been without human intervention, which automatically find the work point.
(2) The grid voltage is automatically stabilized. In order to ensure the consistency of the test conditions, the input voltage of the welding power supply should be stabilized within a certain error range, and the grid voltage is often subject to load and other factors around the impact, there will be greater volatility. The detection system uses micro-controller voltage regulation technology to automatically monitor the power grid.
(3) Harmonic current detection and analysis. Harmonic is an important feature of power electronic equipment, but also a major hazard to the power grid. From the perspective of harmonic suppression, what is important is the magnitude of the harmonics and the real-time nature of the measurement. All functions of the harmonic current detection module based on instantaneous reactive power theory in the system are realized by software and all intermediate quantities of the detection process can be observed and recorded.
(4) Power factor is an important index to measure the power quality of equipment. It reflects the utilization of power by equipment. It is also an important basis for evaluating and developing a new type of welding power source with high efficiency. Electronic control of the welding power supply often cause serious distortion of the input current, the traditional methods of power factor angle to describe the power factor is not applicable, the system uses waveform calculation method, the measured object as a whole, designed for three-phase Power factor measurement module, to avoid the impact of non-sinusoidal signals and three-phase imbalance, to solve the problem can not be accurately obtained in the phase voltage. In order to accurately evaluate the performance of welding power supply provides a new detection method.
(5) Efficiency reflects the power utilization. The detection system realizes simultaneous measurement of input and output power of welding power supply, reduces the influence of fluctuation on measurement, and can observe the change of efficiency under different load conditions. While improving the detection accuracy, New welding power source and the utilization of electrical energy awareness of great help.
(6) Networked measurement and control is an important application of network technology. The current universal application of the Internet, making remote information sharing a reality. Based on the field bus and LAN ultra-long-range mode of operation, you can achieve the past need to detect personnel on-site operation of the work, such as instrument calibration, calibration, fault diagnosis. The test system has provided the necessary technical support for the implementation of this application.
At present, this serialized inspection system enables the testing of welding power supply to continue to develop towards precision, efficiency, automation and informationization. It has been used by nearly 10 large-scale welding power supply manufacturers, testing institutes and schools in China and will be needed in the future To further adapt to the specific needs of each user to make a more personalized design, user-friendly.
3 The above-mentioned three generations of testing equipment basically detect the static electrical parameters of the welding power supply. Only the third generation of products have the function of testing and analyzing the transition process of no-load, no-load and short-circuit. However, Arc load regulation methods are contactor control, there are speed limitations, it is difficult to objectively describe and simulate the dynamic arc.
Usually arc welding process is often accompanied by short circuit transition, arc length changes, current pulses and other factors such as wire speed changes have an impact on the arc, welding power supply on the impact of these factors is its dynamic performance, its good Bad and process performance and stability are directly linked. Therefore, in the comprehensive evaluation of welding power performance and quality, dynamic performance is an important test content. In the second part of the European standard EN 729, the testing requirements for "integrated quality of welding equipment" have been put forward and the implementation cycle of the calibration welding equipment has been proposed. In order to meet the needs of this development, D.Rehfeldt of Germany Hannover University developed a welding dynamic simulator, which is the fourth generation of arc welding power source testing equipment.
The simulator outputs the dynamic parameters from the function generator and is described by a set of high-speed non-linear high-power electronic switch circuits. The dynamic arc and industrial computer are used to collect and process the output response of the welding power source. The system is equipped with a welding analyzer The data files for the chart and test results will be generated automatically. In addition, it can easily use the LAN or the Internet to remotely test the welding power supply. At present, Chengdu Sifang Electric Co., Ltd. has signed a cooperation agreement with Hannover University of Germany to manufacture and sell the aircraft.
With the rapid development of welding manufacturing technology, the international welding standards are changing with each passing day, IEC 60974.10 standards have EMC requirements for welding power supply, China's corresponding national standard will soon be introduced, the EMC testing of welding power supply will again put forward a new Testing tasks, how to develop suitable for welding power research, production, testing needs of EMC testing equipment is an urgent need to address the issue.
Contact: David Piao
Address：No.99 North Wusongjiang Road, Kunshan, Suzhou, Jiangsu, ChinaPR 215300