Date of Award
Vijaia Narapareddy, Ph.D.
Mohammad Matin, Ph.D.
Cuk converter, DC-DC converters, Photovoltaic, Switched-capacitor, Switched-inductor
Renewable energy sources, such as solar energy, are desired for both economic and ecological issues. These renewable energy sources are plentiful in nature and have a terrific capability for power generation. The only drawback of solar energy, which is one of the best forms of energy sources, is that the output has a low voltage and needs to be stepped up in order to be inserted into the DC grid or an inverter for AC applications. To overcome this drawback, a high gain DC-DC power converter is required in this kind of system. These power converters are needed for a better regulation capability with a small density volume, lightweight, high efficiency, and low cost.
In this dissertation, different topologies of a non-isolated high gain step-up Cuk converter based on switched-inductor (SL) and switched-capacitor (SC) techniques for renewable energy applications, such as photovoltaic and fuel cell, are proposed. These kinds of Cuk converters provide a negative-to-positive step-up DC-DC voltage conversion. The proposed Cuk converters increase the voltage boost ability significantly using the SL and SC techniques compared with the conventional Cuk and boost converters. Then, a maximum power point tracking (MPPT) technique is employed in the proposed Cuk converter to get the maximum power point (MPP) from the PV panel.
The proposed Cuk converters are derived from the conventional Cuk converter by replacing the single inductor at the input, output sides, or both by a SL and the transferring energy capacitor by a SC. The main advantages of the proposed Cuk converters are achieving a high voltage conversion ratio and reducing the voltage stress across the main switch. Therefore, a switch with a lower voltage rating and thus a lower RDS-ON can be used, and that will lead to a higher efficiency. For example, the third topology of the proposed Cuk converter has the ability to boost the input voltage up to 13 times when D=0.75, D is the duty cycle. The voltage gain and the voltage stress across the main switch in all topologies have been compared with conventional converters and other Cuk converters used different techniques. The proposed topologies avoid using a transformer, coupled inductors, or an extreme duty cycle leading to less volume, loss, and cost.
The proposed Cuk converters are analyzed in continuous conduction mode (CCM), and they have been designed for 12V input supply voltage, 50kHz switching frequency, and 75% duty cycle. A detailed theoretical analysis of the CCM is represented, and all the equations have been derived and matched with the results. The proposed Cuk converters have been simulated in MATLAB/Simulink and the results are discussed.
Almalaq, Yasser, "Design And Analysis Of A Non-Isolated High Gain Step-Up Cuk Converter" (2019). Electronic Theses and Dissertations. 1558.
Received from ProQuest