Repalle Kusala Pavan Kumar

Bio: Repalle Kusala Pavan Kumar is an academic researcher from VIT University. The author has contributed to research in topics: Buck–boost converter & Ćuk converter. The author has an hindex of 9, co-authored 10 publications receiving 141 citations.

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

Abstract: 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.

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

Abstract: 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.

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

Abstract: 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 non-isolated high step-up DC-DC converters for photovoltaic applications

Abstract: This paper proposes a novel non-isolated high step-up DC-DC converters for photovoltaic applications, where voltage is needs to be step-up without using transformer and coupled inductors. In this paper three novel DC-DC converter topologies are discussed in detail, which are suitable for photovoltaic applications. In this proposed converters, two similar inductors are charges in parallel when switches S 1 , S 2 are ON and discharges in series when switches S 1 , S 2 are OFF. The steady state analysis of proposed converters for continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are discussed in detail. The proposed converters have been designed with rated power 200W, input voltage is 24V and switching frequency is 50kHz. The output voltage of the converter-I, H, HI is 168V, 192V, 216V respectively. The simulation results will verify the validity of the analytical design of the proposed DC-DC converters. The proposed converter topologies are simulated in MATLAB/SEVIULINK.

A novel high step-up DC-DC multilevel buck-boost converter using voltage-lift switched-inductor cell

Abstract: This paper presents a novel high step-up DC-DC multilevel buck-boost converter using voltage-lift switched-inductor (VLSI) cell. To achieve high conversion ratio cascading of conventional DC-DC converter is not a practical solution. Thus high step-up multilevel buck-boost converters are employed to achieve high conversion ratio. The proposed high step-up DC-DC multilevel buck-boost converter is a non-isolated topology which combines the function of voltage-lift switched-inductors (VLSI) cell and voltage multiplier. In this paper voltage-lift switched-inductor (VLSI) cell is used to advance the boost capability of multilevel buck-boost converter. 2N+3 diodes, 2N capacitors, two inductors and single switch are needed to design proposed N-level buck-boost topology. Proposed DC-DC multilevel buck-boost topology can be synthesized by using low voltage rating devices because voltage stress across each power devices is less. The main advantage of proposed DC-DC multilevel topology is high conversion ratio is achieved without using coupled inductor, transformer and extreme duty cycle. The voltage gain of proposed buck-boost multilevel converter is depends upon the duty cycle and number of levels. The proposed buck-boost multilevel converter has been designed for three levels with rated power 200W and output voltage is 220V Input supply voltage is 12V, duty cycle is 70% and switching frequency is 50KHz. The proposed buck-boost multilevel converter topology is simulated in MATLAB/SIMULINK.

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

Abstract: 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.

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

Abstract: 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.

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

Abstract: 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.

X-Y converter family: A new breed of buck boost converter for high step-up renewable energy applications

Abstract: A New breed of a buck boost converter, named as the XY converter family is proposed in this article. In the XY family, 16 topologies are presented which are highly suitable for renewable energy applications which require a high ratio of DC-DC converter; such as a photovoltaic multilevel inverter system, high voltage automotive applications and industrial drives. Compared to the traditional boost converter and existing recent converters, the proposed XY converter family has the ability to provide a higher output voltage by using less number of power devices and reactive components. Other distinct features of the XY converter family are i) Single control switch ii) Provide negative output voltage iii) Non-isolated topologies iv) High conversion ratio without making the use of high duty cycle and v) modular structure. XY family is compared with the recent high step-up converters and the detailed description of XY converter family and its topologies are presented. The simulation results are provided and it confirms the feasibility, functionality and validity of the concepts of the proposed XY converter family.