ABSTRACT
The switched-mode DC-DC converters are some of the most widely used power electronics circuits for its high conversion efficiency and flexible output voltage. These converters used for electronic devices are designed to regulate the output voltage against the changes of the input voltage and load current. This leads to the requirement of more advanced control methods to meet the real demand. Many control methods are developed for the control of DC-DC converters. This thesis presents an interleaved buck DC-DC converter using zero current switching (ZCS) resonant additional inductor and capacitor that mainly used for battery charger application. This converter has a two MOSFETs as a switches along with an interleaved inductor (ZCS) call is added. This allows the proposed interleaved buck DC-DC converter to have higher efficiency and operate with higher switching frequency. The proposed novel interleaved buck DC-DC converter has advantages with the simplicity, low cost, high efficiency and with the behavior of easy control under the (ZCS) condition accordingly reducing the switching losses. The most important advantage is that it offers a lower switching losses and a higher power density. To improve the performance of the converter system coupled inductors are used. This coupled inductors reduce the magnetic size and also improves the converter’s transient performance without increasing the steady-state current ripple. The detailed study of operating principle and design considerations is performed. The calculated efficiency is ensured about 91.11% which is substantially considered being satisfactory performance as achieved in this thesis. Finally, the effectiveness of the proposed control scheme is demonstrated through PSIM simulations. The proposed interleaved buck DC-DC converter using (ZCS) has a straightforward structure, low cost, easy control, and high efficiency. 
As well this thesis presents a novel soft-switching interleaved boost DC-DC converter composed of two shunted elementary boost conversion units and coupled inductors. This converter is able to turn on both the active power switches at zero current switching to reduce their switching losses and evidently raise the conversion efficiency. A DC-DC boost converter is used to step up the voltage. Here, interleaving structure is used to increase the power rating, reduce the input current ripple, output voltage ripple, power loss and to reduce the input current. It uses two feedback loops, similar to current mode control, one for slow outer loop and the other for faster inner PWM control loop. To improve the transient response of the 2-cell converter system, a coupled inductors of energy storage inductors are used. This integrated magnetic design structure reduces size and improves the converter performance, both steady state and transient. The effectiveness of the proposed control scheme is demonstrated through PSIM simulations and experimental work.