Research On Digital High Frequency Inverter Welding Controller

Welding technology is widely used in modern industrial. For the nonlinearity, varying-time and uncertainty in the welding process, traditional analog control is difficult to meet modern welding control requirements in control accuracy, speed and stability.With the development of the welding technologies, control technologies and information technologies, it has become a hotspot to study the digital welding machine system. In this paper, we took researches on the development of welding equipment at home and abroad, introduced digital signal processor-based control technology, and launched a digital welding inverter control system study.This paper introduced the concept of digital welding machine, and proposed a control framework of the digital arc welding control system.On the basis of TMS320LF2407A DSP, we designed digital control systems and human-machine interface of the arc welder. In hardware, this paper described the hardware design of the various parts of DSP control system in detail, including hardware design of DSP minimum system circuits, communication circuits, drive circuits, protection circuits, voltage and current sampling conditioning circuit and human-machine interface. It provided a hardware platform for the digital control of arc welder. We took full account of the welding anti-interference performance in the hardware design, detailed analysis of the welding of disturbance and interference transmission. We designed different welding anti-interference methods for parts of the welder. In the control strategy, we combined the digital PID control method and technology of expert system to design an expert PID controller. Intelligent control is introduced into digital welding control system. The system took a real-time sampling of the current and voltage output, the results were sent into expert PID controller. The controller changed the output of the DSP PWM signals to control the output characteristics of welding. In software, this paper introduces theμC/OS-ⅡRTOS, built a real-time multi-task platform. It keeps the system scalable and easy to update. This paper describes the transplant process ofμC/OS-Ⅱin TMS320LF2407A control system, and designed three tasks for welding control. Among them, a task was designed to control the welding process, another task was designed to achieve a welding machine data communication capabilities, and the finally task was designed to achieve the menu of human-machine interface functions. We also examined the anti-interference software design.In this paper, the digital control system has passed the hardware and software debugging, digital control on the welding control systems had been verified by experiments. To simulate the control effect of expert PID controller by MATLAB, the control effect was satisfactory. Digital welding control system could improve the welding effect significantly through the field welding test.Finally, we made recommendations to the further improvement of the welding inverter after a brief summary. It laid a good foundation for the further study of digital welding control system.