DSP Based Digital Control Of Pulsed MIG

The development of artificial intelligence and digital signal processing technology will be an important driving force for arc welding technique development heading for high efficiency, digitization and intelligence. It is hard for anolog arc welding power supply to realize precised and flexible control, because of its weakness such as complex circuit, low reliability, poor planted ability and high precision requrements for anolog electron parts. Therefor, this paper study digital inverter controller to meet the need of welding inverter applications, by designing the digital control strategy. The research presented here is concentrating on digitization welding inverter based on DSP and CPLD used for PMIG welding, aiming at improving the performance of welding power source.In this paper, we develop a full-digital control system for PMIG using TMS320F2812, EPM7064 and AT89S8252, and establish a full-digital control welding inverter study platform, on the basis of the development of DSP technology and embedded application. In this system, DSP is responsible for the whole management and control for the inverter. CPLD EPM7064 realizes the fuction of digitizing PWM circuit, digitizing protection circuit and filter circuit. MCU is in charge of the control of the man-machine interface system. The communication between DSP and MCU is established by RS-232 protocols.The PMIG welding inverter designed in this paper is capable of performing fuctions as followings load testing and adjusting. First of all, realize PWM digitization, protection and filter circuit digitization by programing software on CLPD and load testing. Second, performs good external static characteristic and dynamic step response characteristic by programing current closed loop control software for PMIG inverter and load testing. At last, realizes arc-voltage closed loop arithmetic verification by programming the new voltage/frequency changing program and load testing. The simulated load test is also made here. The experiment proved that the welding inverter can control the current waveforms precisely and average arc-voltage constantly, and meet the design requirements.Some advices on future research of the welding power source are given, and they would make a found ground for the subsequent study of full-digital controlled welding inverter.