Research On High Frequency Soft Switching Electrolytic Industry Power Supply With Three-phase APFC

Abstract:With the continuous development of the high power switching device in recent years, the high frequency switching power supply has been studied and applied in electrolytic power supply field. Compared with the traditional thyristor rectifier supply, the high frequency switching power supply has the advantages of small volume, high efficiency and wide range of voltage regulation. But some problems exist in the high frequency switching power supply at present, for example, the power factor is low and the soft switch cannot achieve the good effect. Therefore, the research on improving the power factor and reducing the switching loss of high frequency switching power supply is of great significance.In this paper, a three-phase power factor correction converter (APFC) is added in front of the traditional single-stage full bridge DC/DC converter to constitute two levels DC/DC converter series structure. In order to meet the needs of the high power applied in eletrolysis industry, a three-phase double switch interleaved APFC circuit topology is constructed; meanwhile, a controller which meets the topology is designed through improving the one cycle control in this paper,and the condition of realizing soft switching for the converter is analysed.The simulation results show that the harmonic content is reducing, the power factor is increasing, and the output voltage is constant by adding the three-phase double switch interleaved APFC.The later DC/DC converter of two levels DC/DC converter uses the full bridge LLC resonant converter. In this paper, the equivalent modeling of the converter is established with the simplified fundamental analysis method and then the controller of full bridge LLC resonant converter with one cycle control is designed. The simulation shows that, through the optimization designing of the converter’s parameters, the switch tube of full bridge achieves zero voltage switching and the rectifier diode achieves zero current switching, the switching loss decreases obviously, and the efficiency of the converter is improved. After an independent equivalent analysis of the two level DC/DC converters, based on cascaded two levels DC/DC converters, the circuit topology structure of high frequency switching power supply is constructed and then the stability of power supply based on two levels DC/DC converter is analyzed. The analysis of the impedance ratio stability criterion shows that the power supply can work steadily by joining the DC bus capacitor between the two levels of DC/DC converter.In this paper, on the basis of the traditional high frequency switching power supply, a three-phase APFC is added, improving the power factor of the power. At the same time, the LLC resonance technology is brought into the full bridge DC/DC converter, achieving a better effect of soft switching, providing certain theory basis for the high frequency switching power supply used in electrolysis industry. This thesis has fifty-six Figures, one table and sixty-four references in total.