The Research Of Fused Silica Furnace Soft-switching Power Supply Based On APFC

There are many problems in fused quartz power supply, such as heavy equipment, energy consumption, the low efficiency and so on. Compared with the traditional thyristor controlled rectifier power supply, high-frequency soft switching power supply has the advantages of small size transform, low switching losses, high efficiency and the stable output. In this paper, fused quartz furnace power supply is selected as the research object. The three-phase double switching active power factor correction technology and the control strategy are researched and innovated. Main circuit and control circuit of the phase-shifted full-bridge zero-voltage and zero-current switching converter are researched.Main circuit of the power supply is divided into two stages: the forward stage is a three-phase double switching APFC circuit, which can reduce harmonic pollution effectively and improve power factor of the circuit; the backward stage is a phase-shifted full-bridge ZVZCS circuit, the high frequency design reduces the volume of the transformer, the soft switching technology is used to reduce switching losses to zero. Since the traditional fused quartz furnace power supply is low power factor and serious pollution to grid by using three-phase uncontrolled rectifier, APFC technology is researched, main circuit and control circuit of the three-phase double-switch APFC converter are analyzed detailedly. In order to solve the problem of the traditional algorithm is complicated and not conducive to real-time control, a novel single-cycle control strategy is proposed, which has advantages of simple control principle, low component and low cost. Since the traditional fused quartz furnace Power supply transformer is bulky and has much copper and iron losses, a fused quartz furnace soft switching Power supply is designed. Main circuit and control circuit of the ZVZCS converter are analyzed detailedly, small-signal model of the converter is study and the transfer function of the main circuit is derive, the current and voltage double-loop control is achieved in the control circuit by using a UC3875chip. A three-phase double switching APFC circuit and a phase-shifted full-bridge ZVZCS conversion circuit simulation models are built by using SIMULINK of MATLAB, the simulation results proved the correctness of the theoretical analysis. The experimental prototype of high-power soft-switching power supply is built based on the theoretical study and simulation experiments. Experimental results show that the power factor can be improved, the switch can achieve soft switching. Theoretical analysis and prototype experiments have demonstrated the validity of the power supply.