Research On Topology And Generation Methodology For High Gain Non-isolated Boost Converters

In recent years, green renewable sources of energy such as solar and fuel cells, have been more and more important with global warming and the gradual depletion of non-renewable energy in the world. In general, these renewable sources of energy generate low DC voltage output which normally changes over a wide range, and therefore DC-DC converters with high voltage gain are widely required in many renewable energy applications to meet the grid or the load requirements. In addition, the high gain DC-DC converter has been used in HID, communication power, electric cars, medical equipment and other industries. In this context, some fundamental and exploratory researches to achieve high voltage gain, high-performance non-isolated Boost converter are proposed. The contents are shown as follow:Firstly, structural mechanism of basic tapped inductor Boost converter(TI-Boost) is researched in this dissertation on summary of the intrinsic relationship of traditional Boost and TI-Boost. Then the concept of a composite tapped inductor cell structure(CTI) is proposed. This structure integrates a variety of functions: it not only helps to enhance the voltage gain, but also to recovery and utilization of the leakage inductance energy; meanwhile it also has the role of clamping switch voltage which can effectively reduce the switch voltage stress. The composite switching-tapped inductor Boost(CSTI-Boost) and voltage source-tapped inductor Boost converters(CVTI-Boost) are constructed based on the CTI, which can achieve higher voltage gain without the limited duty cycle, and help to depress big spikes of the switch voltage stress. A quadratic composite switching-tapped inductor Boost converter(Q-CSTI-Boost) is also studied, which provides a feasible idea to achieve a higher voltage gain, and continuous input current as the conventional Boost converter.Then, the rectifier circuit composed of the diode-capacitance cell and alternating current transformer(DCC-TR) is analyzed and summarized. The working mechanism and generality of the DCC-TR structure is extracted. On that basis, three diode-capacitance cells(DCC) are discovered for the voltage multiplier rectifier applied to AC pulse sources. The basic Boost converter is divided into three basic parts containing a pulse source, energy buffer portion and output portion, revealing the similarity between DCC-TR and basic Boost converter(B-Boost). On this basis, an idea of topological transformation from DCC-TR to the Boost topology combined with DCC(DCC-Boost) is proposed. A series of DCC-Boost converters with single switch are derived. At the same time, several input parallel DCC-Boost converters with dual switches(IP-CDCC-Boost), and some input series output series DCC-Boost converters(ISOS-DCC-Boost) based on interleaving control, are deduced. The simulated and experimental verification have been conducted for the typical converters proposed.According to innovation idea of modular combination, a novel high voltage gain Boost converter in parallel at the input and in series at the output(IPOS Boost-Boost) is proposed by integrating two basic Boost converters tightly. The IPOS Boost-Boost converter will not only extend the voltage gain for the series output capacitors, but also reduce the input current and output voltage ripples for the interleaving input. Moreover, the switch voltage stress can be reduced to half of the B-Boost converter. At the same time, a high step up input parallel and output series Boost-Sepic converter(IPOS Boost-Sepic) is proposed by the optimal combination of the conventional Boost and Sepic converters. On this basis, a series of IPOS Boost-Sepic converters using coupled inductor(IPOS CI-Boost-Sepic) are derived. Moreover, the IPOS CI-Boost-Sepic converters are further simplified into single switch converters, which is called ICOS CI-Boost-Sepic converter because the Boost converter and the Sepic converter have common input and connect in series at the output. The simulated and experimental results show that these converters have some advantages including high voltage gain, low switch voltage stress and contious input current.In order to derive high step up input-parallel Boost converters based on three state switching cell and dual coupled inductors(TSSC-DCI-Boost), the general laws of an interleaved Boost converter associated with two coupled inductors are drawn. According to the mechanism of coupled inductor for extending voltage gain, the injected voltage source units(IVSU) composed of the two coupled inductors and diode-capacitors are reviewed and summarized. The idea is proposed that IVSU will be respectively inserted into three state switch Boost converters in different position for deducing new topologies with high voltage gain. Based on the mentioned consideration, some input-parallel TSSC non-isolated Boost converters are derived, including the high-end superposition type, low-end superposition type, mixed superposition type, IVPS enhancement type in which the input voltage and the primary winding and secondary winding of coupled inductors are connected in series(IVPS) in a switch mode, and IVS enhancement type in which the input voltage and the secondary windings of coupled inductors are connected in series(IVS) in a mode.The input current ripple will result in serious electromagnetic interference on the first stage converter or power supply, and make power generation less efficient. A series of reduced input current ripple single switch non-isolated Boost converter based on the coupled inductor(RR-CI-Boost) is proposed. Under the proper duty ratio, the high voltage gain can be achieved by adjusting the turn ratio of the coupled inductor, and the voltage stress of the switch is reduced. In addition, the proposed converter can nearly achieve zero input current ripples, and suppress the electromagnetic interference(EMI) on the input power supply circuit.