Design and Analysis of a Non-Isolated High Gain Step-Up Cuk Converter

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

Integrated CMOS Energy Harvesting Converter with Digital Maximum Power Point Tracking for a Portable Thermophotovoltaic Power Generator

This paper presents an integrated maximum power point tracking system for use with a thermophotovoltaic (TPV) portable power generator. The design, implemented in 0.35 μm CMOS technology, consists of a low-power control stage and a dc-dc boost power stage with soft-switching capability. With a nominal input voltage of 1 V, and an output voltage of 4 V, we demonstrate a peak conversion efficiency under nominal conditions of over 94% (overall peak efficiency over 95%), at a power level of 300 mW. The control stage uses lossless current sensing together with a custom low-power time-based ADC to minimize control losses. The converter employs a fully integrated digital implementation of a peak power tracking algorithm, and achieves a measured tracking efficiency above 98%. A detailed study of achievable efficiency versus inductor size is also presented, with calculated and measured results.Interconnect Focus Center (United States. Defense Advanced Research Projects Agency and Semiconductor Research Corporation

An Overview of Fully Integrated Switching Power Converters Based on Switched-Capacitor versus Inductive Approach and Their Advanced Control Aspects

This paper reviews and discusses the state of the art of integrated switched-capacitor and integrated inductive power converters and provides a perspective on progress towards the realization of efficient and fully integrated DC–DC power conversion. A comparative assessment has been presented to review the salient features in the utilization of transistor technology between the switched-capacitor and switched inductor converter-based approaches. First, applications that drive the need for integrated switching power converters are introduced, and further implementation issues to be addressed also are discussed. Second, different control and modulation strategies applied to integrated switched-capacitor (voltage conversion ratio control, duty cycle control, switching frequency modulation, Ron modulation, and series low drop out) and inductive converters (pulse width modulation and pulse frequency modulation) are then discussed. Finally, a complete set of integrated power converters are related in terms of their conditions and operation metrics, thereby allowing a categorization to provide the suitability of converter technologies