Non-isolated DC-DC Research Articles

Universal Soft Switching Dual Active Bridge Converter for Electric Vehicle Charging Infrastructure towards Sustainable Electric Transportation

This paper introduces a modified Dual Active Bridge (DAB) converter integrated with an LLC2 resonant converter tailored for Electric Vehicle (EV) charging infrastructure, emphasizing a unidirectional power flow. The converter implements a two-stage power conversion process, leveraging the DAB’s suitability for high-power applications characterized by enhanced efficiency, low voltage stress, and universal soft switching (ZVS) across all switches. Distinguishing itself from conventional isolated and non-isolated DC-DC converters, the DAB-LLC2 configuration is systematically elucidated in terms of its operating principle, soft switching characteristics, steady-state attributes, output features and crucial design parameters. A meticulous design of a 3kW DAB-LLC2 converter is conducted using MATLAB/Simulink software and the comprehensive results are documented, providing valuable insights into the converter’s performance and applicability for EV charging infrastructure for sustainable electric transportation.

Parametric correction in the control system of the electric propulsion of autonomous underwater vehicles affected by random inputs

The paper deals with the problem of controlling a DC propulsion motor of an autonomous underwater vehicle using a bidirectional non-isolated DC-DC converter. An automatic speed control system with a parametric controller was developed in the Matlab / Simulink package. To reduce energy conversion stages, dc-dc converters are often used to control dc motors AUV. The result of the work is an adaptive control system for the speed of the AUV propeller, which would provide high accuracy for a wide range of speeds and at the same time limit the maximum current and voltage at the armature. The indicators of the quality of performance in various modes of operation were determined, maps of the controller settings were compiled, and parametric correction was introduced. The operation of the system is analyzed and drawbacks are eliminated, such as voltage surges when switching from one speed to another, a decrease in overshoot and settling time. The performance of the system is analyzed under the conditions of random inputs from the propeller. The description of the laboratory stand for the study of the control system is given. A description of the laboratory study of the operation of the "DC converter—engine" system under conditions of random fluctuations in the moments on the motor shaft is given. It is shown that the proposed system has shown itself well under laboratory conditions and the experimental results are consistent with modeling in Matlab / Simulink.

A New Zero Voltage Transition Non-Isolated Bidirectional DC-DC Converter

A New Zero Voltage Transition Non-Isolated Bidirectional DC-DC Converter

Design and Performance Analysis of a Non-Isolated DC-DC Converter With a Fractional-Order Output Filtering Capacitor

Design and Performance Analysis of a Non-Isolated DC-DC Converter With a Fractional-Order Output Filtering Capacitor

A Novel Non-Isolated Bidirectional DC-DC Converter with Improved Current Ripples for Low-Voltage On-Board Charging

This paper presents a novel single-phase non-isolated bidirectional buck converter topology. The proposed converter uses a basic switching cell structure with a coupled inductor and an interleaving switching scheme. This article addresses a crucial challenge in bidirectional DC-DC conversion by prioritizing reducing output current ripples and minimizing filter inductor size. The employed method includes using MOSFETs with fast recovery diodes to mitigate reverse recovery and body diode losses. Furthermore, the optimization of the switching frequency of the output inductor to be twice the actual switching frequency contributes to reducing the component size of the converter. The coupled inductor also helps to reduce stress on components by distributing currents among its legs. The experimental result demonstrates the proposed converter has a very low ripple current as compared to the conventional converter. The low current ripples and smaller filter inductor size enabled by high-frequency operation have improved the efficiency and size of the converter. A common ground between input and output terminals ensures robust performance without common mode current concerns. Overall, the proposed converter represents a significant improvement in DC-DC converters, promising enhanced efficiency, reliability, and compactness in bidirectional DC-DC conversion systems. In order to verify the performance of the proposed converter, a 460 W buck converter prototype was built and tested.

Dual input single Output quadratic Boost converter for DC microgrid

DC-DC converters play a critical role in various applications, including DC microgrids, electrical vehicles, data centres and aerospace power systems. This article provides a description of a non-isolated Dual Input Single Output Quadratic Boost DC-DC Converter (DISOQBC) designed for DC microgrids. PV module and battery are low dc voltage power generators. DC microgrid requires high voltage for its operation effectively. By utilizing the proposed converter, the PV module and battery are integrated with separate sources. Achieving a high efficiency and voltage conversion ratio, the proposed converter is distinguished by low components used. The operation of the converter, component design, steady state analysis, and small-signal model has been reported. The proposed converter's benefits include the converter's ability to handle more than one source, deliver more gain than the conventional converter, simple control and reduced losses. The outcome of simulating the converter validates the proposed converter's theoretical operation. The laboratory prototype is ultimately employed to validate and verify the performance of the proposed DISOQBC.

Non-Isolated Bidirectional DC-DC Converter Design And Low Power Application for EV Charging Station

Today, the negative impact of charging on the grid is becoming a major concern as the number of electric vehicles increases. The charging topologies such as V2G, V2H and V2V are being studied to solve this problem. The most critical issue in this context is the design and use of appropriate infrastructure and equipment. In this study, firstly a low-cost and high-efficiency non-isolated bidirectional DC-DC converter suitable for DC charging stations is designed. The designed converter was analysed both by analytical methods and by operating at low powers. Secondly, a real-world implementation of V2V and V2H topologies has been performed using these designed converters. In the application study, a DC charging station model was created by using 4 of these converters as charging units. The 90-minute operation of the designed charging station was realised according to a rule-based algorithm. Accordingly, it has been shown that the efficiency of the non-isolated bidirectional DC-DC converter designed is 95%. It is also proved that 54.16% of the EVs load can be shifted to off-peak time period using V2V topology in real world application. According to the results, it is understood that the isolated and high-power version of the designed converter is suitable for charging stations.

Modeling, design and validation of DC-DC landsman converter for low-power electric vehicle battery charging applications

As the world moves towards sustainable development, the reduction of air pollution is considered an important factor. Consequently, the transportation sector is moving from conventional internal combustion engine vehicles to electric vehicles (EVs). To encourage EV usage, governments are working towards installing more public charging systems. These systems invariably use a DC-DC converter to ensure the supply of an appropriate voltage to charge the battery. In developing countries, the majority of users prefer electric bikes and electric rickshaws, which require low power. Therefore, it becomes necessary to use low-power converters suitable to charge these batteries. In such systems, non-isolated DC-DC converters play an important role. This work is intended to explore the use of the Landsman converter for EV battery charging. The motivation behind the work is explained, and the state of the art of EV battery charging research is reviewed to show the research gap. The operation of the proposed converter is explained in detail with its dynamic loop and nodal equations. The gain equation and the memory elements design are detailed with the corresponding equations. The model of the proposed converter is provided with the loss calculation. The system is simulated on MATLAB R2022b software, and the simulation results are provided to show the behavior of voltage and current in each component. To validate the design, a 100 W hardware prototype is implemented using discrete components to supply a resistive load, and to charge a 48 V Li-ion battery. The corresponding results are provided to validate the design and operation. A comparison of the proposed converters’ performance parameters with other non-isolated converters is provided. The topology is seen to provide an instantaneous efficiency of 88% during the prototype testing for resistive load, and an efficiency of 89.6% while charging a 48 V Li-ion battery, wherein, the efficiency magnitudes are the experimental values obtained through real-time measurements on Keysight IntegraVision Power Analyzer PA2203A, during the testing of the hardware prototype, as presented in section . Consequently, Landsman converter is seen to be an attractive converter for EV battery charging applications.

Modulation of Wide Voltage Range Interface DC-DC Converter in DC Distribution System

Bipolar DC distribution systems rely on various power sources like photovoltaics and distributed energy storage, each with its unique voltage characteristics. To accommodate these fluctuations, interface converters must adjust over a wide voltage range. The bipolar non-isolated DC-DC converter emerges as a promising solution due to its versatile modulation capabilities, reduced switch voltage stress, and cost-effectiveness. This article explores how wide voltage range regulation is achieved in bipolar DC-DC converters interfacing with bipolar DC power grids. It delves into the operational strategies and modulation techniques employed, ensuring stable output despite varying input voltages. Design considerations and challenges associated with implementing such converters are also discussed. An experimental platform was constructed to validate the proposed methodology. Through rigorous testing and analysis, the effectiveness of the topology's operation mode was confirmed. Real-world data from the experimental setup provided insights into the converter's performance under different operating conditions, supporting its applicability for bipolar DC distribution systems. In summary, this article provides a comprehensive examination of wide voltage range regulation in bipolar DC-DC converters, highlighting their potential to enhance efficiency and reliability in bipolar DC power grids. Through theoretical discussions and practical validation, it contributes to the advancement and adoption of these converters in modern energy systems.

A Review and Comprehensive Study on DC-DC Converters

Background: DC-DC converters are used in various applications based on their required voltage capabilities ranging from milli volts to thousands of volts. Methods: This review paper discusses various voltage boosting techniques, such as buck-boost, switched inductor, switched capacitors, isolated converters, etc., and provides a detailed evaluation of the literature and comparison of different DC-DC converters. Results: This study reports a number of storage elements included, such as inductors and capacitors as well as switches and diodes. Their features along with methodologies, merits, complexity, efficiency, and voltage gain have been tabulated. A comprehensive study, converter classification based on the characteristics, and a detailed analysis of isolated and non-isolated DC-DC converters have also been provided. Conclusion: As this study provides a comparison of each isolated and non-isolated converter's comprehensive gain, this research may help in future topology optimization for the choice of the ideal converter for applications. In addition, the examination of each isolated and non-isolated converter's comprehensive gain comparison has also been presented in this paper.

Robust digital voltage mode control of buck converter with enhanced tracking performance

The digital voltage controller of power converters is used because it has many advantages over its analog counterparts. Thus, in this paper, a controller of digital voltage mode is designed and analyzed for a non-isolated DC-DC buck converter in continuous conduction mode (CCM). First, an analog controller is designed using a Bode plot to achieve the desired stability margins in the frequency domain. Next, the analog controller is discretized using bilinear transformation with the pre-warping method. The characteristics of the discretized compensator can be maintained close to the corresponding analog compensator as long as a proper sampling time is selected. The digital control scheme is simulated with a nonlinear DC-DC buck converter model in MATLAB/Simulink to investigate the controller performance. The simulation results demonstrated the validation of the proposed digital voltage-mode control design approach. The developed digital controller eliminates DC error by tracking the reference voltage, achieving a fast transient response, maintaining specified stability margins, and effectively rejecting large disturbances.

A non-isolated synchronous buck DC-DC converter, ZVS topology under CCM and DCM conditions

Today, the main challenge of miniaturization and integration of power converters is reducing the volume of parts, eliminating capacitors and inductors.This paper proposes a non-isolated synchronous buck converter (NSBC) under soft switching practice. This converter uses the zero voltage switching (ZVS) topology, which not only provides soft-switching conditions for the converter switches but also prevents the voltage kicking off the two ends of the main switches from being off-state due to self-resonance. To achieve the highest voltage gain in different working cycles, complementary switching approach and use of non-isolated Dc-Dc converter for simultaneous switching of two switches will be used.The non-isolated synchronous buck DC-DC converter with ZVS is to use in some parts of the converter for providing a purpose range of output voltage. In addition, the implementation of the proposed converter control circuit is conducted very simply and needs lower costs. To confirm relations in converter theory, the results of a laboratory sample in the discontinuous and continuous modes are examined. It should be noted that the proposed converter can operate under different levels of voltage, which requires a protection heat policy. The proposed converter implements under the nominal 30-V input and 40 KHz switching frequency, which touches on issues on both sides of discontinuous conduction mode (DCM) and the continuous conduction mode (CCM) conditions and experiment as an example two rates of power 30W and 20W respectively, and also has an acceptable interest rate, which will be evaluated and compared with three different types of similar modes.

SPICE Modelling-Assisted evaluation of dynamic on-resistance characterization in Schottky p-GaN HEMTs amid synchronous buck transient instabilities

This study addresses the critical gap in dynamic on-resistance characterization for GaN HEMTs within the initial unstable state in a non-isolated DC-DC converter, where the output voltage and currents fluctuate and exhibit overshoots or undershoots before stabilizing to their steady-state values, a domain within solar photovoltaic (PV) Maximum Power Point Tracking (MPPT) implementations which is crucial yet insufficiently examined. The authors present a novel multi-pulse test circuit within a synchronous buck converter configuration, complemented by SPICE simulation. This combination allows for the accurate assessment of clamping circuits' performance during transient states, significantly improving the precision of RDS(ON) measurements in unsteady phases. The approach deviates from conventional methods by merging empirical data with simulation insights to validate the efficacy of clamping circuits. The experimental results affirm the methodology's precision, with the highlighted Circuit V showcasing a marginal deviation of 2.32 % from existing benchmarks. This finding substantiates the method's dependability and practicality contributing to the GaN power electronics field. In addition, this research provides a powerful analytical tool for RDS(ON) evaluation, culminating in the design of a test PCB that synergizes with both simulated and empirical evidence, contributing future research in GaN HEMT power converter applications.

Isolated bidirectional DC-DC Converter: A topological review

Bidirectional DC-DC converters (BDCs) are certainly an important power electronic converter for managing bidirectional power flow in various applications. It offers the ability to flow power in both directions, which is useful in systems with renewable energy sources and energy storage. BDCs are becoming increasingly important in various applications, including renewable energy systems, electric vehicles, and energy storage. The development of new BDC topologies and control strategies is expected to further improve their efficiency and performance. Non-Isolated Bidirectional DC-DC Converters (NBDCs) and Isolated Bidirectional DC-DC Converters (IBDCs) are the two main types of BDCs with different isolation properties and trade-offs in terms of size, cost and performance. Topological classification of BDCs further distinguishes various BDC types based on their configurations and voltage-boosting techniques. IBDCs are preferred over NBDCs due to high-power applications, and wide voltage range with higher efficiency; the performance of IBDCs is improving day by day. To provide a framework for comparison in implementing novel configurations or identifying the best converter for a given application, this study is concentrated on each topology and its usual applications. Soft switching converters are also discussed pointed to Resonant Power Converters (RPCs) for the application into Electric Vehicles (EVs). It is worth noting that the choice of BDC depends on the specific requirements of the application, such as power level, voltage range, efficiency, and cost. A detailed comparison, application, advantage and disadvantage table can be useful in comparing the characteristics of different BDCs and selecting the most suitable one.

Review, Properties, and Synthesis of Single-Switch Non-Isolated DC-DC Converters with a Wide Conversion Range.

The cascaded connection of power converters extends conversion ranges but requires careful consideration due to high component count and efficiency concerns, as power is processed redundantly. Furthermore, using several active switches that must be turned on simultaneously may introduce significant drive and control complexity. To overcome this limitation, single-switch quadratic DC-DC converters have been proposed in the literature as a prominent choice for various applications, such as light-emitting diode (LED) drivers. Nevertheless, the motivation behind the conception of such topologies, beyond extending the conversion ratio, remains unclear. Another unexplored issue is the possibility of obtaining single-switch versions of cascaded converters consisting of multiple stages. In this context, this work investigates the synthesis of single-switch non-isolated DC-DC converters for achieving high step-down and/or high step-up based on the graft scheme. Key issues such as the voltage gain, additional stresses on the active switches, component count, and behavior of the input current and output stage current are addressed in detail. An in-depth discussion is presented to identify potential advantages and shortcomings of the resulting structures.

A Novel Soft Switching Non-Isolated Bidirectional dc–dc Converter Without Any Extra Auxiliary Switch

In this paper, a new zero-voltage-switching (ZVS) non-isolated bidirectional DC-DC converter without any extra auxiliary switch is introduced. In the proposed converter, by applying an auxiliary circuit, soft switching condition is provided for all semiconductor elements regardless of the power flow direction and without any extra voltage stress. Each of the main switches provides soft switching conditions for the other switch. Additionally, each of the switches can be used as a synchronous rectifier switch in both power flow directions. The auxiliary circuit only consists of two coupled inductors with the converter main inductor and two diodes, which operate with a zero-current-switching (ZCS) condition. Since, all of the converter inductors are implemented on a single core, the presence of coupled inductors doesn’t increase the converter volume considerably. The detailed operating analysis of the proposed bidirectional converter and the design method of the main circuit is presented. Also, the theoretical analysis of the proposed bidirectional converter is verified with a 100W experimental prototype converter.

Review of DC-DC Partial Power Converter Configurations and Topologies

The Partial Power Processing (PPP) concept has garnered attention as it enables the down-sizing of converter and component ratings. Unlike conventional power processing, PPP addresses a portion of the transferred power, leading to a reduction in conversion losses. Throughout this paper, the state of the art of isolated and non-isolated DC-DC converter topologies will be revised. Partial Power Converter (PPC) systems represent one of the main streams of PPP, which, based on isolation requirements and converter connections, can further be divided into isolated converters, such as: Input-Parallel-Output-Series (IPOS), Input-Series-Output-Parallel (ISOP), and, Input-Series-Output-Series (ISOS), or non-isolated converters. This work intends to evaluate and differentiate the characteristics of each type of topology while developing analytically possible connections that may require further research and reviewing metrics that help in fair comparisons of different PPC arrangements, operating under different conditions. A thorough revision is provided for DC-DC converter topologies due to their increased importance in present-day applications, such as energy storage, Electric Vehicles (EVs), and Photo-Voltaics (PVs).

Modular Circuit Synthesis Oriented Modelling Approach for Non-Isolated DC-DC Converters in DCM

The continued and envisioned large-scale integration of renewable energy sources as a reaction to rising global temperatures and climate change will need a readily available DC grid to increase commissioning and operating efficiency. The effective operation of these grids is predicated on the correct control of its main control points. A plethora of DC-DC converters that find use in DC microgrids act as the main control points. DC-DC converters are non-linear and can operate in different modes with completely unique characteristics. To utilise classical control techniques, laborious equivalent linear models are derived for DC-DC converters using averaging modelling schemes. The application and limitations of these modelling techniques are well captured in the available literature. The most common limitation of the available modelling schemes is that more focus is dedicated to converter attributes like order, functionality and operating mode, even when optimal power flow and voltage regulation within the DC network are of more interest. Structure-based modelling techniques like the use of basic building blocks nullify converter attributes in the modelling process which translates to modelling efficiency. In light of the merits seen with the use of basic building blocks when modelling converters in CCM, the current study extends these merits to converters operation in DCM. Similar to modelling converters in CCM, modelling techniques that are available in the literature continue to consider converter attributes in the modelling process for DCM operation. Moreover, the two modes of operation are treated as unique entities and often modelled in a non-unified manner, which compromise modelling efficiency since the same converter can operate in a different state solely based on loading. The aim is to increase modelling efficiency but also nullify operating mode in the modelling process. The same basic building blocks are now modelled as two-port networks for DCM operation and adopted based on the exact configuration of a specified converter to compute its steady-state and dynamic models. All the advantages seen when modelling converters in CCM using basic building blocks are retained and augmented when considering DCM operation. Thus, any converter with well-defined basic building blocks can be easily modelled solely based on the connection of constituent basic building blocks.

A novel SIMIDCBC topology driven PMSM for PEV application

Nowadays, the usage of renewable energy based electric vehicles is increased for reducing CO2 emissions, usage of fossil fuels, energy saving, and transportation cost. As a result, it becomes the most significantly run with combined energy sources and it is good choice which minimizes the energy consumption from charging stations. The available renewable energy is integrated to power-train through power-electronic interface; such interface consists of three-phase inverter with DC-DC boost converter. The combined energy sources like solar-PV/battery are integrated to power-train by employing multi-input non-isolated step-up DC-DC converter for providing continuous power to drive the vehicle. The multi-terminal topologies have efficient, reliable performance, continuous input current, high step-up gain over the conventional DC-DC converters. In this work, a unique framework of combined energy powered switched-inductor based multi-input DC boost converter topology has been proposed to drive the PMSM. The performance of proposed SIMIDCBC topology driven PMSM for PEV application under constant and variable speed conditions are verified by using MATLAB/Simulink tool, simulation results are presented.

High gain interleaved DC-DC converter with ripple-free input current and low device stress

ABSTRACT A non-isolated DC-DC converter which yields high voltage gain and suitable for photovoltaic (PV) applications is described in this research article. The high gain converter proposed in this paper is synthesised by combining several voltage gain extension techniques viz. coupled inductors, voltage-lift capacitor, and diode-capacitor multiplier (DCM) cells. Since the input stage is interleaved, and the switches are operated complimentarily, the source current ripple is nullified and switch current rating is minimised. Due to the hybrid voltage gain extension techniques adopted while synthesising the converter, the voltage stress on the switches is only 10.5% of the output voltage. To validate the proposed concept, experimental results are obtained from 18 V-380 V, 150W prototype converter which is operated at 50 kHz. The proposed converter yields a voltage gain of 21.11 at 92.83% efficiency under full-load condition. During closed-loop operation, the proposed converter quickly settles down to its nominal output voltage of 380 V when the input voltage and load current values are subjected to step variations. The superior features of the proposed converter are highlighted by comparing it with similar and recent state-of-the art high gain converters.