Research Of Input Rectifier Topologies For Welding Inverter Power

In the recent welding area, welding power is more and more widely used in several places. At the same time, research of rectifier topology for welding power has been receiving more and more concern. Although it is important to get excellent power source external characteristic of welding power, harmonic distortion rate of AC input current, which is called THD, and power factor, etc, should not be ignored. In this paper, varies kinds of rectifier topologies which can be used in a welding inverter power are discussed and given detailed theoretical research as well as simulation studies.In this paper, two common 12-pulse wave rectifier topologies of the welding inverter power are introduced at first. Then, according to requirement of the output DC voltage, a 12-pulse wave rectifier based on the axial splitting autotransformer is analyzed. Both the winding connection and relationship among the voltage vectors of the autotransformer are discussed. There are no influences of three-phase AC voltage's phase-order variation to AC input current and DC output voltage, which is analyzed in this paper, with the role of balancing reactor in the circuit introduced in it. Finally, simulation analysises of every possible situation happended in the real world are made for this new rectifier topology.Using 12-pulse wave rectifier topologies dicusssed obove into a welding inverter power can result in serious distortion of AC input current, big THD value, low power factor. Based on it, a new rectifier topology which can be used in a welding inverter power—Three-Phase High-Frequency PWM rectifier topology, is introduced, whose circuit structure and working principle are discussed. In this paper, mathematical model of this rectifier topology is derived and control parameters of the control system are designed, which uses voltage-current double closed loop PI control method. Simulation analysis based on above is given for this rectifier topology.The outpout inverter-rectifier circuit of the welding inverter power is actually a Phase-Shift Full Bridge inverter. In this paper, the circuit structure and working principle of Phase-Shift Full Bridge inverter is simply introduced. The realization of Soft-Switch and the loss of secondary side duty cycle are also discussed. This paper gives the small single model of Phase-Shift Full Bridge ZVS PWM inverter and design related control parameters of the control system, which is studied clearly in the control strategy—switching between voltage loop and current loop according to some certain conditions. Finally, simulation analysis and performance accomplishment of this part are made.In this paper, simulation analysis for this whole system—combination of the 12-pulse wave rectifier based on the axial splitting autotransformer or Three-Phase High-Frequency PWM rectifier topology with Phase-Shift Full Bridge ZVS PWM inverter, are made. A 200A/10kw welding inverter power source prototype, which uses a 12-pulse wave rectifier topology on the basis of the axial splitting autotransformer as the power supply, is developed. Some related experiments are studied on it, and several results are gotten which are for the analysis. According to these experimental results, it is known that both the performances of this power source prototype and the circuit working situation of the rectifier are excellent, which reaches all kinds of performance index requirements of this welding inverter power system.