This paper proposes a novel nonisolated single-input dual-output three-level dc–dc converter (SIDO-TLC) appropriate for medium- and high-voltage applications. The SIDO-TLC is an integration of the three-level buck and boost converters, whose output voltages are regulated simultaneously. Reducing voltage stress across semiconductor devices, improving efficiency, and reducing inductors size are among the main merits of the new topology. Moreover, due to the considerably reduced volume of the step-down filter capacitor, a small film capacitor can be used instead, whose advantages are lower equivalent series resistance and a longer lifespan. A closed-loop control system has been designed based on a small-signal model derivation in order to regulate the output voltages along with the capacitors’ voltage balancing. In order to verify the theoretical and simulation results, a 300-W prototype was built and experimented. The results prove the aforementioned advantages of the SIDO-TLC, and the high effectiveness of the balancing control strategy. Furthermore, the converter shows very good stability, even under simultaneous step changes of the loads and input voltage.

A Novel Single-Input Dual-Output Three-Level DC–DC Converter

The automobile companies are focusing on recent technologies such as growing Hydrogen (H2) and Fuel Cell (FC) Vehicular Power Train (VPT) to improve the Tank-To-Wheel (TTW) efficiency. Benefits, the lower cost, ‘Eco’ friendly, zero-emission and high-power capacity, etc. In the power train of fuel cell vehicles, the DC-DC power converters play a vital role to boost the fuel cell stack voltage. Hence, satisfy the demand of the motor and transmission in the vehicles. Several DC-DC converter topologies have proposed for various vehicular applications like fuel cell, battery, and renewable energy fed hybrid vehicles etc. Most cases, the DC-DC power converters are viable and cost-effective solutions for FC-VPT with reduced size and increased efficiency. This article describes the state-of-the-art in unidirectional non-isolated DC-DC Multistage Power Converter (MPC) topologies for FC-VPT application. The paper presented the comprehensive review, comparison of different topologies and stated the suitability for different vehicular applications. This article also discusses the DC-DC MPC applications more specific to the power train of a small vehicle to large vehicles (bus, trucks etc.). Further, the advantages and disadvantages pointed out with the prominent features for converters. Finally, the classification of the DC-DC converters, its challenges, and applications for FC technology is presented in the review article as state-of-the-art in research.

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Survey of DC-DC Non-Isolated Topologies for Unidirectional Power Flow in Fuel Cell Vehicles

In this paper, a new topology of two-stage cascaded switched-diode (CSD) multilevel inverter is proposed for medium-voltage renewable energy integration. First, it aims to reduce the number of switches along with its gate drivers. Thus, the installation space and cost of a multilevel inverter are reduced. The spike removal switch added in the first stage of the inverter provides a flowing path for the reverse load current, and as a result, high voltage spikes occurring at the base of the stepped output voltage based upon conventional CSD multilevel inverter topologies are removed. Moreover, to resolve the problems related to dc source fluctuations of multilevel inverter used for renewable energy integration, the clock phase-shifting (CPS) one-cycle control (OCC) is developed to control the two-stage CSD multilevel inverter. By shifting the clock pulse phase of every cascaded unit, the staircase-like output voltage waveforms are obtained and a strong suppression ability against fluctuations in dc sources is achieved. Simulation and experimental results are discussed to verify the feasibility and performances of the two-stage CSD multilevel inverter controlled by the CPS OCC method.

Novel Cascaded Switched-Diode Multilevel Inverter for Renewable Energy Integration

In order to obtain a high step-up voltage gain, high-efficiency converter, this paper proposed a dual switches dc/dc converter with three-winding-coupled inductor and charge pump. The proposed converter composed of dual switches structure, three-winding-coupled inductor, and charge pump. This combination facilitates realization of high step-up voltage gain with a low voltage/current stress on the power switches. Meanwhile, the voltage across the diodes is low and the diode reverse-recovery problem is alleviated by the leakage inductance of the three-winding-coupled inductor. Taking all these into consideration, the efficiency can be high. This paper illustrated the operation principle of the proposed converter; discussed the effect of leakage inductance on voltage gain; the conditions of zero current shutting off of the diodes are illustrated; the voltage and current stress of the power devices are shown; a comparison between the performance of the proposed converter and previous high step-up converters was conducted. Finally, a prototype rated at 500 W has been established, and the experimental results verify the correctness of the analysis.

Dual Switches DC/DC Converter With Three-Winding-Coupled Inductor and Charge Pump

Regarding the inherent structure of some nonpolluting resources such as fuel cell (FC) stacks and photovoltaic (PV) panels, the output exhibits a low voltage, which cannot be employed in the common conventional utilizations. Accordingly, an interference dc–dc converter is extremely required. This paper demonstrates the feasibility of using an ultra-high-voltage-gain dc–dc converter in either the FC or the PV applications. While keeping the high voltage gain, the proposed topology illustrates low switches’ voltage stress resulted in high efficiency. The continuous and discontinuous conduction operation modes, as well as efficiency analysis, are investigated. The prototype setup of 250 W and 400 V output voltage is implemented. The proposed dc–dc converter merits involving ultra-high-voltage ratio, low switches’ voltage stress, and high efficiency are verified via experimental results.

A Novel Nonisolated Ultra-High-Voltage-Gain DC–DC Converter With Low Voltage Stress

This paper presents a novel non-isolated switched inductor floating output DC-DC multilevel boost converter. Non-isolated high gain DC-DC converters are essential for fuelcell applications to boost the supply voltage with high conversion ratio. Conventional DC-DC boost converter is not suitable for high gain applications because of high voltage stress and high duty cycle. The proposed converter is non-isolated floating output DC-DC multilevel converter which combines the switched inductor and voltage multiplier functions to achieve high voltage gain. 2N-1 capacitors, 2N+2 diodes, two inductor and only one switch is required to design N-level DC-DC proposed converter. In the proposed converter topology blocking voltage across each device is less; hence proposed converter can be synthesized by using low voltage devices. The main advantage of proposed topology is high voltage gain is achieved without using transformer and extreme duty cycle. The gain of proposed converter is depends upon the number of levels at the output side. The proposed converter has been designed for three levels with rated power 450W, input voltage is 24V, output voltage is 480V and switching frequency is 50kHz. The proposed converter topology is simulated in MATLAB/SIMULINK.

A novel non-isolated switched inductor floating output DC-DC multilevel boost converter for fuelcell applications

This paper presents a novel non-isolated dual output hybrid DC-DC multilevel converter. The proposed converter topology is suitable for photovoltaic applications where two voltages are needed at the same time with opposite polarity. The proposed DC-DC converter topology is the combination of two high gain multilevel DC-DC converters, one is multilevel boost converter and another is multilevel cuk converter. Two output voltages with opposite polarity are achieved by using only single switch and single input supply. Positive output voltage is obtained from multilevel boost converter and negative output voltage is obtained from multilevel cuk converter. The gain of the converter can be increases by adding appropriate number of capacitors and diodes without disturbing the main circuit. The proposed converter has been designed for photovoltaic applications with rated output parameters 200W, 240V and 200W, −228V. The input voltage is 12V and switching frequency is 50 KHz. The Proposed converter topology is simulated in MATLAB/SIMULINK.

Non-isolated dual output hybrid DC-DC multilevel converter for photovoltaic applications

In this paper, a modified cascaded H-bridge multilevel inverter (MLI) is proposed and designed for solar applications. Generally, as the level of conventional multilevel inverter increases, the required number of switches and size increases. The proposed topology is cascade of unit stages which involves 5 switches and two voltage source; moreover a unit stage is capable of generating 5 levels. Also, the detailed analysis of cascaded multilevel inverter is discussed which incorporates three different methodologies involving less number of power devices in order to generate maximum number of levels. This results into reduction in gate drive circuitry and less switching losses. The proposed MLI is designed for power 1.5kW and Inphase level shifting SPWM technique has been incorporated in which 5kHz carrier wave is compared with 50Hz of sinusoidal wave with a modulation index of 0.8. As a result, total harmonic distortion (THD) is achieved as 4.71% with LC-filter for above mentioned multilevel inverter. The circuits are modeled and simulated with the help of MATLAB/SIMULINK.

http://ieeexplore.ieee.org/iel7/6900020/6920919/06922468.pdf

A modified cascaded H-bridge multilevel inverter for solar applications

This paper presents a sepic based dual output DC-DC converter, which is suitable for solar applications where two output voltages are needed at the same time. The proposed converter topology is the combination of sepic converter and high gain multilevel boost converter. Only one input source and switch is required to obtain two output voltages at the same time. One output voltage is obtained through high gain multilevel boost converter and other output voltage is obtained through sepic converter. Sepic converter operates in two modes, step-up or step-down depending on the duty cycle. The output voltage levels of high gain multilevel boost converter can be increases by adding diodes and capacitors without disturbing main circuit. The converter has been designed for 12V input supply with rated output parameters 180W, 230V and 50W, 36V. Switching frequency of applied gate pulse is 50 KHz with 75% duty cycle. Simulation is carried out using MATLAB/SIMULINK.

A novel sepic based dual output DC-DC converter for solar applications

Solar energy is one of the renewable energy which is used to generate electricity with the help of PV arrays. DC-DC converter is used to step up the DC voltage from PV arrays and then it is connected to an inverter for AC applications. Conventional inverters have many issues like non sinusoidal output, high total harmonic distortion (THD), high switching stress and more number of switches. So multilevel inverter (MLI) have gained much importance over conventional inverters for high voltage and high power applications, due to the increased number of voltage levels producing less number of harmonics. In this paper, a cascaded asymmetric multilevel inverter is proposed which contains minimum number of switches and can be employed in AC applications using solar energy. The proposed topology consists of 25 output levels using 10 switches with near sinusoidal output, thereby reducing gate driver circuitry and optimizing circuit layout. Asymmetric multilevel inverter is more advantageous than symmetric multilevel inverter in obtaining more number of output levels using same number of voltage sources. The other advantages of proposed topology are low voltage stress and reduced THD. The THD for proposed inverter circuit is only 4.98%. Modeling and simulation is carried out using MATLAB/SIMULINK.

Mahajan Sagar Bhaskar Ranjana

Papers

A novel non-isolated switched inductor floating output DC-DC multilevel boost converter for fuelcell applications

Non-isolated dual output hybrid DC-DC multilevel converter for photovoltaic applications

A modified cascaded H-bridge multilevel inverter for solar applications

A novel sepic based dual output DC-DC converter for solar applications

A cascaded asymmetric multilevel inverter with minimum number of switches for solar applications