Practical implementation of high power and efficiency dc-dc full-bridge PWM boost converter

Design and simulation problems of high power full-bridge boost converter with 175...320 VDC supply voltage are considered. The converter under investigation consists of a full-bridge inverter, a boost high-frequency transformer, a diode rectifier connected to a capacitive filter and an active load. Additional inductance, connected in series with the transformers primary winding, is brought in the converters structure to achieve soft commutation of power switches and limitation of the current switched by them, in order to improve the reliability of the device and increase its efficiency of energy conversion. Selection of the additional inductance value is an important task, because too much of it could not allow to provide load power requirements, and too small of it could bring about defects of expensive power semiconductor elements. The choice of additional inductance is also complicated by the difficulty of measuring the transformer leakage inductance with sufficient accuracy. This problem is solved using the proposed method of selection the additional inductance value, based on an analysis of the mathematical model and on an analytical description of the output inverter current curve. We also propose increasing of energy transformation efficiency by variation of the PWM carrier frequency. The curves that measured on real device 100 kW (175 ... 320V / 610V) show correctness of the model and the proposed method of selection of the carrier frequency and the additional inductance value.