| The appearance and development of digital inverter welding power source are theimprovement of welding technology. It is said that digital inverter welding powersource is the digital revolution or IT revolution of welding technology. It not onlypromotes development of welding power source, but also takes good acts on the futuredevelopents. This paper introdues the cencept of digitalization firstly, then analyzesthe characteristics of digital inverter welding power source. According to the presentstate of based on push-pull and low energy input GMAW short-circuit welding controlmodel, and the trend of these control methords became more precision, we introducethe digitized technical into the control process, this should add to the stability andprecision, the spatter rate should be reduced and the weld bead would be improved atthe same time.The application field and development trend of DSP are introduced briefly and itswork principle, stucture characteristics and select are explained in detail. This paperemphasizes on the component parts and control principle of digitalized IGBT inverterGMAW power source. Main circuit, control circuit, protection circuit and drive circuitare respectively analyzed. Furthermore, the software and hardware are also interpreted.The main circuit uses a soft switch and full-bridge inverter structure, selectesIGBT as the inverter device, the inverter frequency is20KHz. The main circuit iscomposed of rectified filter circuit, inverter circuit, intermediate-frequency transform-er, output rectifier and output filter.High performance32-bit DSP TMS320F2812is adopted as control kernel.Universal PWM is adopted to control output power and output characteristic throughcontrolling IGBT switch on time. The digital signal from microprocessor are firstlyconverted into analogy signal, which is then modulated by pulse width modulate(PWM) chip UC3846and two chips555into four pulses. At last the pulses are used todrive IGBT after they are magnified by exclusive drive module. The system samplesoutput current in real time and bring it to DSP for A/D conversion.The installation and setup of DSP develop environment CCSv3.3and develop toolICETEK-5100USB are illuminated，too.This paper also intruduces the resource distribution of DSP and the functions ofperipheral circuit are given. Aim to typical problems in welding process: over current,over heat, over voltage and lack voltage, a corresponding protection circuit isdesigned. Reliability and anti-jamming are considered in main circuit and control circuit.Various noises probably appear in the whole system, as well as their causation, areanalyzed systematically. Then, in order to reduce their bad infections, some hardwareand software measures are adopted while designing schematic chart, PCB board, andcompiling code. The stucture and function of main program and interrupt servicesubroutine are explained. System software, which is made of C language, is veryefficient for limiting noise and improving system response-speed.Corresponding data and waveforms are recorded in the experiment, and problemsoccurred in experiment are investigated. The experiment results show that the inverterpower source has high reliability, a strong ability of anti-jammi-Ing, basically fulfillthe original design concept and requirements.At last, some advices on future research for the welding power are given, and theywill make a found ground for tomorrow’s research of digital welding power. |
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