Closed Loop Control For Three-phase PFC Of Arc Welding Power Supply

Eliminating harmonic pollution and improving power factor are the quite important task in the field of power electronics. Correction of the power supply's power factor has become necessary request, and the criterion is strict more and more. In the welding power supply field, this kind criterion is also going to be implemented. The power of welding power supply is very large, so the matter it caused is more attention-getting.This thesis summarized the development of three-phase PFC of Arc Welding , analysed several three-phase PFC circuit, With the merit of AC current and DC voltage is controllable, then the three phase half-bridge topology is choose as the front power factor corrector of welding power supply. We mapped three phase variable first to a-β plane then to d-q plane using PARK transformation, things is simplified accordingly. In the d-q coordinate, the main circuit's unit power factor run principle is analyzed, and the flow of the main circuit current was gained, so did the basic mathematical relation of the input and output and the restriction of various parameters to realize unit power factor, and also offered the theory of how to design the control system. For the six power switches, we adopt the space vector modulation method, at the same time we analyzed synthesize mode of the vector, and then chose the best one. The good behave of this topology in the unit power factor rectifier state is better than the others circuit topology.By the principle analysis of the main circuit, we concluded that three-phase PWM rectifier was a very good circuit topology for PFC; it has the ability to run in four quadrants. The rectifier can run in different state using different control. That is mean this characteristic of the three-phase boost topology has many application field.Compared to the questions of temperature excursion,aging of analog control system. We use the TMS320LF2407A digital control chip made in TI Company in this paper. The digital chip included SVPMW waveform generator, and it can be used to realize the PFC, also it has convenient debug and the flexible control function features, with the feature it can be realize digital control of the three-phase PFC system easier. TI Company's 2000 series DSP is a good choice for digital power supply. Put the 2000 series DSP into three-phase PFC system of power supply, the...