Development Of A Limited Double- Bipolar Soft Switch Welding Power Supply

With the rapid development of power electronics technology,the power level of power equipment is higher and higher,the corresponding frequency is higher and higher,and the application field of high voltage DC / DC converter is more and more extensive.Because of the high voltage,high power and high frequency,the design of high voltage DC converter and the selection of components are very difficult.Therefore,the softswitching technology is used to realize the high frequency of the power conversion elements.The output power of DC-DC converter can reduce the loss of switch greatly and improve the transmission efficiency and reliability.The finite bipolar control strategy is selected as the final scheme.Compared with the shift control strategy,the finite bipolar hysteresis arm(ZCS)fundamentally solves the problem that the hysteresis arm in the shift control strategy is not good at realizing ZVS.Because no inductor is needed,the duty cycle loss problem is also solved.The primary side series isolation capacitance,the original side circulation greatly reduced.Due to the complexity of welding power supply and the frequent change of load in the short-circuit-load-no-load state,in order to reduce the loss and improve the reliability,the realization of soft switching in the full load range is the most important task.In this paper,we choose two mature soft-switching full-bridge topologies,both of which adopt the finite bipolar control,the super-forearm realizes zero-voltage switch and the lag-arm realizes zero-current switch.The original side of transformer adopts series saturation inductance and insulation capacitor scheme.The output power of the converter is 20 kW and the frequency 20KHZ-50 KHZ is used to design the converter.The control principle and sequence of the converter topology are analyzed respectively,and the parameters of welding power source are designed.The parameters of the designed components are created by PSpice simulation software,and the hardware circuit simulation is carried out.Adjust the components and circuits according to the results,so as to achieve the best results.Then the soft-switching inverter power supply is debugged and tested.The temperature rise and transfer efficiency are detected in the hard switching state,the overarm ZVS and the lag arm ZCS are detected in the full load range under the soft switching condition,and the temperature rise and transfer efficiency are tested in this state.Secondly,the soft and hard switching is compared.Finally,from the angle of different switching frequency and different circuit structure,the two kinds of soft-switching topology are compared and analyzed,and some conclusions are drawn,which is instructive to follow-up research.