An Interleaved Soft Switched High Step-Up Boost Converter With High Power Density for Renewable Energy Applications

In this article, a novel soft switched interleaved boost structure with a simple auxiliary circuit is proposed which is suitable for stand-alone loads or ac grid applications. In this topology, coupled inductors and switched capacitor cells of parallel modules are merged to obtain high voltage conversion ratio. The converter also has the capability of adding extra switched capacitor cells to attain very high voltage gain. To provide soft-switching condition in the wide range of output power, a new zero-voltage transition auxiliary circuit is employed which is responsible for soft switching of both phases and benefits from low conduction losses, the minimum number of semiconductor elements, and only one auxiliary gate-driver. These merits provide very high efficiency at both full-load and light loads. More importantly, no auxiliary magnetic components are utilized by taking advantage of the leakage inductance of coupled inductors for the resonant network. All semiconductor components operate under soft switching alleviating the reverse recovery problem and switching losses. Besides, the converter benefits from common ground between input and output which simplify voltage feedback. The experimental results of the interleaved converter prototype with 400-V output voltage at 400 W and 100 kHz switching frequency are provided. The full load efficiency of 98% was achieved and the power density was observed 1.9 W/Cm3

Performance Improvement of AC-DC Power Factor Correction Converters For Distributed Power System

In present situation, the increase in the utilization of computers, laptops,uninterruptable power supplies, telecom and bio-medical equipments has become uncontrollable as its growth is rising exponentially. Hence, increase in functionality of such equipments leads to the higher power consumption and low power density which provided a large market to distributed power systems (DPS). The development of these DPS posed challenges to power engineers for an efficient power delivery with stringent regulating standards; this is the motivation and driving force of this research work. The objective is to minimize the switching losses of front-end converters employed in DPS, with the primary aim of achieving nearly unity power factor operation of converters.Single-phase and three-phase rectifiers are increasingly used in the field of alternating current – direct current (AC-DC) power converters as front-end converters in DPS. For power factor correction (PFC) stage, conventional single-phase AC-DC PFC boost converter is the most suitable topology because of its inherent advantages. These PFC boost converters exhibit poor dynamic regulation of output voltage owing to low pass filter in the voltage feedback loop. Research effort has been made to mitigate this problem of AC-DC PFC boost converters. An extended pulse width modulation switching technique has been investigated and proposed especially for single-phase and three-phase AC-DC PFC boost converters to improve the dynamic response of output voltage during transient periods

Robust Control of a Multi-phase Interleaved Boost Converter for Photovoltaic Application using µ-Synthesis Approach

The high demand of energy efficiency has led to the development power converter topologies and control system designs within the field of power electronics. Recent advances of interleaved boost converters have showed improved features between the power conversion topologies in several aspects, including power quality, efficiency, sustainability and reliability. Interleaved boost converter with multi-phase technique for PV system is an attractive area for distributed power generation. During load variation or power supply changes due to the weather changes the output voltage requires a robust control to maintain stable and perform robustness. Connecting converters in series and parallel have the advantages of modularity, scalability, reliability, distributed location of capacitors which make it favorable in industrial applications. In this dissertation, a design of µ-synthesis controller is proposed to address the design specification of multi-phase interleaved boost converter at several power applications. This thesis contributes to the ongoing research on the IBC topology by proposing the modeling, applications uses and control techniques to the stability challenges. The research proposes a new strategy of robust control applied to a non-isolated DC/DC interleaved boost converter with a high step voltage ratio as multi-phase, multi-stage which is favorable for PV applications. The proposed controller is designed based on µ-synthesis technique to approach a high regulated output voltage, better efficiency, gain a fast regulation response against disturbance and load variation with a better dynamic performance and achieve robustness. The controller has been simulated using MATLAB/Simulink software and validated through experimental results which show the effectiveness and the robustness

An Interleaved Configuration of Modified KY Converter with High Conversion Ratio for Renewable Energy Applications; Design, Analysis and Implementation

In this paper, a new high efficiency, high step-up, non-isolated, interleaved DC-DC converter for renewable energy applications is presented. In the suggested topology, two modified step-up KY converters are interleaved to obtain a high conversion ratio without the use of coupled inductors. In comparison with the conventional interleaved DC-DC converters such as boost, buck-boost, SEPIC, ZETA and CUK, the presented converter has higher voltage gain that is obtained with a suitable duty cycle. Despite the high voltage gain of the proposed converter, the voltage stress of the power switches and diodes is low. Therefore, switches with low conduction losses can be applied to improve the converter efficiency. Moreover, due to utilization of interleaving techniques, the input current ripple is low which makes the suggested converter a good candidate for renewable energy applications such as PV power system. Operation principle and steady-state analysis of the proposed converter in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are discussed in detail. Also, theoretical efficiency of the proposed converter is calculated. Finally, in order to evaluate the proposed converter operation by a renewable energy source such as a PV, the simulation results are presented. Moreover, a 220W prototype of the presented DC-DC converter is designed and implemented in the laboratory to verify its performance

Efficient, High Power Density, Modular Wide Band-gap Based Converters for Medium Voltage Application

Recent advances in semiconductor technology have accelerated developments in medium-voltage direct-current (MVDC) power system transmission and distribution. A DC-DC converter is widely considered to be the most important technology for future DC networks. Wide band-gap (WBG) power devices (i.e. Silicon Carbide (SiC) and Gallium Nitride (GaN) devices) have paved the way for improving the efficiency and power density of power converters by means of higher switching frequencies with lower conduction and switching losses compared to their Silicon (Si) counterparts. However, due to rapid variation of the voltage and current, di/dt and dv/dt, to fully utilize the advantages of the Wide-bandgap semiconductors, more focus is needed to design the printed circuit boards (PCB) in terms of minimizing the parasitic components, which impacts efficiency. The aim of this dissertation is to study the technical challenges associated with the implementation of WBG devices and propose different power converter topologies for MVDC applications. Ship power system with MVDC distribution is attracting widespread interest due to higher reliability and reduced fuel consumption. Also, since the charging time is a barrier for adopting the electric vehicles, increasing the voltage level of the dc bus to achieve the fast charging is considered to be the most important solution to address this concern. Moreover, raising the voltage level reduces the size and cost of cables in the car. Employing MVDC system in the power grid offers secure, flexible and efficient power flow. It is shown that to reach optimal performance in terms of low package inductance and high slew rate of switches, designing a PCB with low common source inductance, power loop inductance, and gate-driver loop are essential. Compared with traditional power converters, the proposed circuits can reduce the voltage stress on switches and diodes, as well as the input current ripple. A lower voltage stress allows the designer to employ the switches and diodes with lower on-resistance RDS(ON) and forward voltage drop, respectively. Consequently, more efficient power conversion system can be achieved. Moreover, the proposed converters offer a high voltage gain that helps the power switches with smaller duty-cycle, which leads to lower current and voltage stress across them. To verify the proposed concept and prove the correctness of the theoretical analysis, the laboratory prototype of the converters using WBG devices were implemented. The proposed converters can provide energy conversion with an efficiency of 97% feeding the nominal load, which is 2% more than the efficiency of the-state-of-the-art converters. Besides the efficiency, shrinking the current ripple leads to 50% size reduction of the input filter inductors

Review on State-of-the-Art Unidirectional Non-Isolated Power Factor Correction Converters for Short-/Long-Distance Electric Vehicles

Electrification of the transportation sector has originated a worldwide demand towards green-based refueling infrastructure modernization. Global researches and efforts have been pondered to promote optimal Electric Vehicle (EV) charging stations. The EV power electronic systems can be classified into three main divisions: power charging station configuration (e.g., Level 1 (i.e., slow-speed charger), Level 2 (i.e., fast-speed charger), and Level 3 (i.e., ultra-fast speed charger)), the electric drive system, and the auxiliary EV loads. This paper emphasizes the recent development in Power Factor Correction (PFC) converters in the on-board charger system for short-distance EVs (e.g., e-bikes, e-trikes, e-rickshaw, and golf carts) and long-distance EVs (passenger e-cars, e-trucks, and e-buses). The EV battery voltage mainly ranges between 36 V and 900 V based on the EV application. The on-board battery charger consists of either a single-stage converter (a PFC converter that meets the demands of both the supply-side and the battery-side) or a two-stage converter (a PFC converter that meets the supply-side requirements and a DC-DC converter that meets the battery-side requirements). This paper focuses on the single-phase unidirectional non-isolated PFC converters for on-board battery chargers (i.e., Level 1 and Level 2 charging infrastructure). A comprehensive classification is provided for the PFC converters with two main categories: (1) the fundamental PFC topologies (i.e., Buck, Boost, Buck-Boost, SEPIC, C k, and Zeta converters) and (2) the modified PFC topologies (i.e., improved power quality PFC converters derived from the fundamental topologies). This paper provides a review of up-to-date publications for PFC converters in short-/long-distance EV applications.Qatar National Research FundScopu

Development of novel non-isolated unidirectional DCDC multistage power converter configurations for renewable energy applications- hardware implementation and investigation studies

Abstract: In the last decades, there is a rapid development towards new energy sources due to the increasing demand of energy and cost of the fossil fuels. Renewable energy sources getting more popular day by day due to government support and carbon dioxide (CO2) emission reduction policy to reduce greenhouse gas emissions. Photovoltaic energy generation is the excellent example of energy generation through various serious parallel arrangement of a small voltage generating cells or modules. There are directly use of synchronous generators to transfer power to grid from hydro energy plant, geothermal energy plant, bio-fuel energy plants. However, the photovoltaic energy generation systems requires the power electronic converters system to satisfy the demand of realtime application or electric grid. Therefore, for real-time applications or before feeding energy to the grid via inverter, photovoltaic systems linked with DC-DC converters, which have high-voltage conversion ratio capability. Thus, DC-DC power converter is the paramount constituent in the photovoltaic power conversion stage. This research work carried out in focusing on hardware implementation and investigation studies of novel non-isolated unidirectional DC-DC multistage power converter configurations for renewable energy application. The comprehensive review of various unidirectional non-isolated DC-DC multistage power converters are presented and it is found that not all of them have the capability to convert low voltage into high voltage, thus not suitable for photovoltaic energy applications. It is investigated that there is a scope to design new DC-DC multistage power converter topologies configurations with high voltage conversion ratio by employing a new arrangement of reactive elements and semiconductor devices. A new breed of DC-DC multistage power converters called “X-Y converter family” proposed for photovoltaic application by utilizing the switchedinductor, the switched capacitor, the voltage lift switch capacitor and modified voltage lift switched capacitor, voltage doubler and multiplier boosting techniques. The derivation of voltage conversion ratio, advantage of each converter of X-Y family and hierarchy of X-Y family is discussed. The research work also proposed a new DC-DC multistage power converter without a magnetic component for photovoltaic application by utilizing the concept of switched capacitors. An original Transformer and Switched Capacitor (T-SC) based multistage power converter proposed for high-voltage/lowcurrent photovoltaic applications by combining the feature of the boost converter, transformer and switched capacitor. New Nx IMBC (Nx Interleaved Multilevel Boost Converter) or Cockcroft Walton (CW) Voltage Multiplier based Multistage/Multilevel Power Converter (CW-VM-MPC) converter topologies are presented to achieve maximum voltage conversion ratio by utilizing the feature of Cockcroft Walton (CW) voltage multiplier. Moreover, the proposed multistage power converter compared with each other as well as recently proposed multistage power converters in term of voltage conversion ratio, number of devices and costs.D.Eng. (Electrical and Electronic Engineering

An Adaptable Interleaved DC-DC Boost Converter

A.H. Weinberg presented his classic boost topology in his 1974 publication intended for use in satellites. It comprises minimal external components and uses multiple coupled coil systems to provide a boost of up to 2x. Its simplicity makes it inherently robust and reliable as minimal components means lower chance of failure. While its simplicity makes it attractive it has limited boost capability which makes it unsuitable for many modern day applications. No significant investigation has been carried out on adapting the Weinberg topology for high boost operation so far as can be ascertained. An investigation into adapting the Weinberg converter for high boost operation is presented in this thesis. A novel topology is developed which preserves the simplicity, reliability and efficiency of the Weinberg design while achieving boost ratios >2x. An analysis of the proposed topology is provided and mathematical expressions are derived to quantify the voltages and currents in relevant component for a given set of operating conditions. All coupled windings share a single core and are arranged so the magnetic flux does not reverse direction which further reduces loss in the magnetic core material. The coupled coils clamp the MOSFET drain voltage to an amount much lower than the output voltage which allows lower breakdown versions with lower intrinsic ON-resistance to be used leading to reduced conduction losses. Modelling of circuit losses and their sources allows optimal selection and positioning of components and finds wound component and MOSFET conduction losses contribute around 70% of the total circuit loss. Modelling and trialling of wound component geometries is carried out to optimise magnetic coupling and reduce leakage inductance. Working prototypes are developed and used to verify the mathematical claims through experimentation. Overall system efficiency of 94.1% is achieved at a boost ratio of 8.8x and an output power of 257W. Overall system losses are reduced from 11% to 6% by simply optimising the magnetic assembly. However optimisation of the magnetic assembly is more involved and may be less tolerant to variation which may hinder repeatability but the results are very positive despite crude, hand-wound magnetic coils and standard quality silicon components being used; which is a promising sign