Wide Input Voltage Isolated Dc-Dc Converters With Interleaving Control

In this thesis, a novel interleaving control strategy for dc/dc converters is proposed and applied to a new isolated dc-dc converter configuration with two paralleled half-bridge structure at the primary side and a new rectification method at the secondary side of the transformers, aiming at to optimize the design of transformers and reduce the rectifier diodes voltage stresses when input voltage range is wide. The concept of this new control scheme is to interleave the gate signals with an angle in two identical PWM controlled half-bridges, which leads two half-bridges working alternatively when input voltage is high, but in series when input voltage is low. Due to the halved transformer primary voltage, the rectifier diode voltage stresses are reduced distinctly.Moreover, different PWM control methods including symmetric PWM control and DCS PWM control can be used for the two half-bridge. These two control strategy leads to the same transformer design, the same switches stresses and the same rectifier diodes voltage stresses. But the interleaving control based on DCS PWM control leads two in four main switches achieve ZVS by using the energy tapped in the leakage inductance, which provides a possibility to reduce the switching losses. Therefore, the proposed converter has a potential to operate at higher efficiencies and switching frequencies.The principle of operation and features of the new interleaving control scheme, the proposed topologies and the small signal model based on state average method for both topologies are illustrated and verified experimentally on 100-400V input voltage, 50V/10A output prototypes. The experimental results show that the proposed approach is feasible.