Converter Topology Research Articles

A Multilayer Software-Defined System for High-Performance Electric Vehicle Energy Conversion

A multi-layer software-defined architecture is developed based on a type of elementary power module to improve the energy conversion performance of electric vehicle (EV) system. The proposed structure is composed of three layers: (1) application function layer for the interfaces with various types of electrified loads/sources and the corresponding control functions, such as single/three-phase grid, battery, motor, resistor; (2) elementary module layer for providing desired number of basic power module with local functions of variable frequency soft switching (VFSS) and model predictive control (MPC) to increase the efficiency with better transient performance; (3) interconnection management layer for the coordination and interconnection between the application function layer and elementary module layer to construct the complete power converter topology with desired number of elementary power module for the satisfaction of the interfaced load/source. The merits of the designed architecture include the reconfigurability to be suitable for different types of EV applications, all non-isolated topologies with common mode noise attenuation capability, improved efficiency and dynamic performance by VFSS and MPC of the elementary power module, high accuracy and robustness of the multi-layer control without being influenced by the parametric modeling error from various applications. The proposed multi-layer architecture is validated with experimental tests.

A New Triswitching Double Duty High Voltage Gain Boost Converter for DC Nanogrid Application

The Tri-switching Double Duty Converter (TSDDC) is a new non-isolated high gain DC-DC boost converter topology presented in this paper for 400V PV-based DC Nanogrid application. In a conventional DC nanogrid system, two DC-DC converter has been used, one for stepping up the voltage & the other for maximum power point tracking mechanism (MPPT). The proposed TSDCC can perform both operations in a single stage. The proposed converter has been controlled by two duty ratios ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\delta _{1}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\delta _{2}$</tex-math></inline-formula> ) with the help of three switches. The highlighting feature of TSDDC are i) Controlled on two different duty cycles ii) High voltage gain at low duty ratio iii) Lower voltage stress on switches and diodes. The TSDDC is simulated for 500W power with 400V. The working of the converter is explained in detail for continuous conduction mode (CCM). In addition, design guideline and comparative study are also presented. Furthermore, a control scheme is implemented that controls MPPT(maximum power point tracking). A lab prototype of TSSDC was developed for 21V-400V, 400W and the switching frequency is 50kHZ. The proposed TSDDC converter's operating concept and controllability are verified by the simulation results.

Passive Component Optimization for Current-Source-Inverters

In addition to the actual semiconductor components and the cooling solutions required to dissipate losses, passive components account for a large part of the volume of power electronic converters. This publication presents methods for optimising the volume or occupied PCB board area of the passive components of current source inverters (CSIs). For this converter topology, these are primarily composed of the filter capacitors placed on the output terminals and the DC link inductance acting as the main energy storage device in the DC link. Design equations for the design of these components are presented first. In addition to the basic relationships for determining the capacitance or inductance of the respective components, other constraints for their design are also taken into account. Furthermore, an optimisation process is given for both the filter capacitors and the DC link inductance, with which the volume or the occupied board area of the respective components can be designed as small as possible. On the basis of the optimisation results for various input parameters, analytical relationships are then determined that can be used to quickly and easily estimate the volume and area at the beginning of a converter design process.

Efficient Wireless Power Transfer Topology for Phone Charging Application

Abstract: Wireless power transfer scheme used on phone chargers are expected to have high efficiency, and reliability. However, existing AC-DC converter schemes were shown to be susceptible to leakage inductance and have lower regulation or excessive power losses. Output voltage regulation is a concern for wireless power converter topologies due to the need for additional shunt devices at DC output. In this paper, literature survey on various wireless power transfer scheme is performed with specific focus on phone charging applications. A modified topology using impedance matching transformer is presented with circuit analysis and LT spice simulation results. It is shown that the proposed topology can deliver better output voltage regulation at various coupling coefficients indicating a superior circuit performance for various separation distances between transmitting and receiving coil.

A hybrid bridgeless AC‐DC converter topology

SummaryBridgeless ac‐dc converters are the optimal choice for many applications, as they offer many advantages such as low distorted supply current, high power factor, and improved efficiency. This paper presents a new topology for a single‐phase bridgeless ac‐dc converter. The proposed hybrid topology is based on integrating the inverting and non‐inverting buck‐boost dc‐dc converters that are connected to the ac supply through an LC filter. To insure sinusoidal supply current, the proposed hybrid bridgeless ac‐dc converter is operated in discontinuous current mode. The proposed converter has many merits, such as a reduced number of components, enhanced efficiency, and soft start‐up capability. The operation modes and design of the proposed converter are presented. In addition, a design method is proposed for the input LC filter to minimize the voltage stress across switches. Moreover, a small signal model for the proposed converter is developed. The proposed converter topology is simulated to evaluate the dynamic behavior and verify the accuracy of the presented small signal model. Furthermore, an 850 W prototype is developed to validate the features of the proposed converter experimentally. Tight voltage regulation, sinusoidal supply current, and near‐to‐unity power factor operation are observed from the results, regardless of supply or load disturbances.

Isolated Zvs-Pwm DC-DC Converter Based on the Variable Capacitor Technique

This paper introduces a new static power conversion principle, based on the variable capacitance of a capacitor arrangement. As an example of the proposed technique, an isolated ZVS-PWM dc-dc converter topology is proposed. Circuit operation and theoretical analysis, with emphasis on the soft-commutation process, are included in the paper. To validate the theoretical analysis and verify the operation of the converter, a proof-of-concept experimental prototype with 960W power rating, 400 V input voltage, 48 V output voltage and 100 kHz switching frequency was designed, constructed and tested in a laboratory. An additional attribute of the proposed technique is the reduction of the voltage across the power semiconductors to two-thirds of the dc bus voltage, when the duty cycle is equal to 0.5. The proposed technique can be extended and used to generate several other topologies of isolated and nonisolated dc-dc converters.

Part II: State-of-the-Art Technologies of Solar-Powered DC Microgrid with Hybrid Energy Storage Systems: Converter Topologies

Over the past few years, there have been significant advancements in Microgrid (MG) systems, particularly in the field of power electronics. These advancements aim to address the needs of the grid and loads, while integrating low-voltage, non-linear, and highly sensitive power sources, such as solar PV modules, batteries, and supercapacitors. It is crucial to select the appropriate converter configuration and power converters in MG systems, as they greatly impact their optimal performance. To achieve the best results, numerous architectures and converter configurations have been suggested for integrating different energy sources. As a result, a considerable number of research articles have been published, necessitating a thorough review. This article continues studies of Part I and presents a comprehensive overview of various architectures based on the arrangement of different sources and provides a detailed analysis and discussion of these architectures. This article covers thirty-three different categories of DC-DC converters, both isolated and non-isolated. These converters are divided into subcategories, such as conventional type, switched-capacitor type, soft-switching type, multi-phase type, and multilevel type. The article also evaluates the suitability of these topologies based on factors such as high conversion gain, power decoupling, efficiency, isolation, power handling capabilities, and compact design. The critical examination and comparative study presented in this work can be valuable for industry professionals and academics in selecting the most suitable architectural and power converter topologies for optimal performance.

A Modular Multilevel Converter-Based Pulsed Electric Field Generator Design for Electroporation Applications

After a short historical background and mentioning common application areas and different clinical modalities of pulsed electric fields and the phenomena such as electro permeabilization and electroporation are introduced based on the concept of the basic mechanism. Subsequently, pulse generation (PG) and the adapted modular multilevel converter (MMC) topology that is to be covered are introduced including the operating principles and very basic analysis. Finally, performance of the proposed MMC with four half bridge submodules is tested on a prototype built in laboratory. A bidirectional voltage is produced with 80 V amplitude pulsating at 100 kHz operation frequency.

Enhanced Power Factor Correction and Torque Ripple Mitigation for DC–DC Converter Based BLDC Drive

A novel approach to the design of power factor correction (PFC) and torque ripple minimization in a brushless direct current (BLDC) motor drive with a new pulse width modulation (PWM) technique is demonstrated. The drive was designed to have a better power factor (PF) and less torque ripple. On the other hand, the modified Zeta converter is used to enhance the power factor of the proposed system. The modified Zeta converter is operated in discontinuous inductor current mode (DICM) by using a voltage follower technique, which only needs a voltage sensor for power factor correction (PFC) operation and DC-link voltage control. The output voltage of the VSI is determined by switching patterns generated by the PWM-ON-PWM switching strategy, and it reduces the torque ripples. The proposed drive is developed and simulated in a MATLAB/Simulink environment. The power factor of 0.9999 is produced by the PFC modified zeta converter topology and the PWM-ON-PWM scheme reduce the torque ripple in the commutation region by 34.2% as compared with the PWM-ON scheme. This demonstrates the effectiveness of the suggested control method.

Influence of compressive stress on the magnetic characteristics of grain-oriented material under non-sinusoidal excitation

Electric machines are subjected to mechanical stress during their operation, which significantly affects the magnetic characteristics of the core material. Furthermore, as the converter topologies evolve, the induced harmonic content increases. The analysis of magnetic properties due to both magnetomechanical effects and harmonics is rarely addressed. This work provides a deeper insight into the core loss behavior by analyzing the impact of mechanical stress on the hysteresis characteristics of magnetic materials subjected to non-sinusoidal excitation. A qualitative analysis based on the measured characteristics is presented to study the material behavior under sinusoidal and non-sinusoidal excitations. An analytical approach based on the Lavers’ formula and loss separation theory is presented.

A comprehensive review of single-phase converter topologies with 2ω-ripple suppress

A comprehensive review of single-phase converter topologies with 2ω-ripple suppress

Modeling and Control of a Hybrid-Fed Triple-Active Bridge Converter

In general, the structures of Multi-Active Bridge (MAB) converters that can be found in the literature are usually based on voltage converters. However, in some cases, it could be interesting to have a current-fed input due to load characteristics or operation constraints. This leads to a hybrid MAB structure mixing both current-fed and voltage-fed bridges. In this paper, a new hybrid-fed, fully coupled Triple-Active Bridge (TAB) converter topology with two voltage-fed ports and one current-fed port is studied, modelled and controlled. In the first place, a generalized average model (GAM) is developed for this system. After that, a reduced-order model is elaborated in order to simplify the behavioral study and control of this coupled system. A control strategy was also proposed in this paper, based on the developed mathematical model. Simulation results using Matlab/Simulink are presented to validate this study.

Part I—Advancements in Power Converter Technologies: A Focus on SiC-MOSFET-Based Voltage Source Converters

Power converter technologies have become vital in various applications due to their efficient management of electrical energy. With the growing prominence of renewable energy sources such as solar and wind, the high penetration of power electronic converters has been justified. However, ensuring power quality has emerged as a significant challenge for grid-connected power converters. The divergence from the ideal sinusoidal waveform in terms of magnitude and frequency impacts both grid-side currents and voltages. Several studies have proposed solutions to address power quality issues at the load side. The advancement of power converters has been fueled by the development of high-performance microprocessors and the emergence of high-speed switching devices, such as SiC-MOSFETs. This paper focuses on the design of voltage source converters, particularly those based on SiC-MOSFET semiconductor devices. The article presents the design of H-Bridge cells, discusses two-level voltage source converters based on cascade H-Bridge cells in a parallel configuration with experimental fault analysis, addresses the seven-level voltage source converter topology, and explores the design and experimental results of the matrix converter. The findings underscore the importance of considering the entire converter design for improved performance at high switching frequencies. The article concludes by summarizing the main outcomes and implications of this research.

Scalable-flexible architecture and power management strategy for a rural standalone DC community grid

Roof-top solar PV and battery systems at individual homes form standalone DC nanogrids to electrify off-grid remote locations. To improve the reliability and sustainability of these installations, interconnections are required, forming a DC Community Grid (DCCG). A novel 380 V DCCG with 72 V nanogrid (home) members is proposed for this low voltage standalone DCCG. It is also proposed to adopt a decentralized power management strategy which utilizes the concepts of DC bus signaling and adaptive droop control. Power flow algorithm based on adaptive droop equations are developed for individual converter interfaces so that each of the subsystems operate independently but in coordination. Only local measurements of input/output currents and voltages of the particular interface are required. Therefore, these are applicable to any of the converter topologies used as an interface for the renewable sources, batteries and nanogrid interconnections. The decentralized approach will mitigate the dependencies of DCCG on the communication network. With the proposed architecture and power management strategy, addition or removal of loads, sources, or storage units at nanogrid level or community level can be done as plug-and- play without modifying the existing system. The system has been extensively simulated and analyzed using MATLAB/Simulink R2021b and further experimentally verified with closed loop operation using Spartan – 6 XC6SLX25 FPGA in FTG256 package. The experimental verification proves that the bus voltage variation is within the limits set by the power management algorithm while desired power sharing is achieved.

A Review on Recent Advances in Matrix Converter Technology: Topologies, Control, Applications, and Future Prospects

Matrix converters (MCs) are AC-AC power conversion topologies widely explored and applied in the industry for their attractive features of sinusoidal input and output currents, considerable size reduction, and reliable operation due to the omission of bulky passive components. Considerable research has made this technology a serious contender to the indirect AC-DC-AC topologies in industrial applications. This paper comprehensively reviews the state-of-the-art MC technology and its prospects. Furthermore, it presents the advancements in the topological structures of direct/indirect MCs and their modulation and control algorithms over the past decade. It also reports the recent progress in multiphase direct/indirect MC structural and control structures. This paper is aimed at providing comprehensive information to the researchers and engineers on MC technology’s current industrial applications and the research scope as the world moves towards AI and digitalization.

A New Isolated Topology of DC–DC Converter Based on Piezoelectric Resonators

This paper presents a new isolated topology of DC-DC converter based on piezoelectric resonators. Contrary to most existing topologies, the proposed one uses the natural isolation of piezoelectric resonators to isolate the converter's output from the input and vice-versa. Considering the resonators' constraints, our study focuses on the most efficient isolated conversion cycle with zero-voltage switching (ZVS) operations. The case studied is a highly efficient step-down isolated DC-DC converter with a gain ranging from 0 to 1 and an input voltage up to 360 V. The converter uses two piezoelectric resonators working in series. The conversion principle is validated thanks to a prototype operating at a frequency around 95 kHz. Experimental measurements are made on a wide range of input voltage from 12 V to 360 V with a conversion ratio of 0.0165 to 0.95. The output power reaches either 179.1 W with an 89% efficiency at 360 V input voltage and 346 V output voltage, or 4.5 W with a 97.2% peak efficiency for a 48 V to 45.8 V conversion, using a 25 mm piezoelectric disc with a thickness of 2 mm and 1 mm respectively. An efficiency higher than 80% is measured over a wide range of operating points.

Comparative Analysis and Evaluation of the Different Active Cell Balancing Topologies in Lithium Ions Batteries

Series connected batteries must have their cells balanced whenever charging and discharging to extend battery lifespans, assure safe operation, and increase battery pack useful capacity. It also causes charge imbalance issues, which will result in battery cell damage and battery life loss. Several charge/discharge equalization circuits have been suggested however, presently there has been no work regarding the comparison and evaluation of the speed and efficiencies in both modes. In this study, cell balancing on dc-to-dc buck-boost converter and interleaved flyback converter topologies operating in discontinuous current mode are analyzed, designed, and implemented. A simulation model of the converter-based topologies of an active cell balancing system is proposed and designed along with a power loss analysis, efficiencies, and control technique. With the purpose of establishing an energy storage application, the system’s cells are grouped into 8 series cells for SOC balancing and 2 series cells for voltage balancing circuit design. Power loss analysis is performed to analyze the efficiency of these two converter topologies to identify which system performs better. In SOC balancing in charging mode, the buck-boost and interleaved flyback converters’ power efficiencies are 85.596% and 65.1521% respectively and during voltage balancing 93.9078% and 73.1506% respectively.

A Scalable DC/DC Converter Topology With Modularized Energy Storage for High Energy Physics Applications

This paper presents the design and control of a high-power modular DC-DC converter for electromagnets used in high energy physics applications. The fundamental building modules, herein called bricks, can either be connected to the grid or to separate energy-storage components. The proposed modular converter enables independent power flow control among the bricks under control that is agnostic to mission profiles. In particular, the proposed converter design and control allow for independent control of currents delivered from each brick, while respecting the total voltage constraints, and losses optimisation of the converter without compromising the desired electrical performance. In addition, the cost potential of the converter is briefly analysed. The performance of the proposed modular converter is validated experimentally on a full-scale lab prototype rated at 800 kW. The proposed converter demonstrates how separating the total storage into a number of storage bricks can be beneficial to adapt the design of a modular converter to a large range of profiles and operating constraints. It is shown that up to 30% cost savings can be achieved by eliminating converter components in the storage and grid connection, while the converter performance on the load is maintained and the same amount of energy is recycled.

Analysis and Design of Bidirectional Parallel-Series DAB-Based Converter

Unprecedented expansion of renewable, energy storage and fast charger system applications has diversified the bidirectional converter designs over the past decade. This paper presents a new dual-active bridge (DAB) converter topology which employs parallel and series switches arrangements for low-voltage (LV) bridge configurations. The additional switch inclusion provides high dc conversion gain, which enables attractive fast charger applications. The performance of the proposed DAB-based converter with wide dc range has been investigated through several design techniques and comparisons. The use of use of silicon carbide devices (SiC) in higher power conversion significantly improves switching losses. However, unsupervised design will result in significant switching losses and increased electromagnetic emissions. Since the DAB-based converter's high switching frequency allows operation with smaller magnetics, the system stray capacitance plays a critical role. The common-mode current (CMC) propagated through the system's stray capacitance generates undesired electromagnetic interferences (EMI) and impacts the soft-switching achievable range. To overcome the common-mode current circulation issue, design solutions have been employed to reduce the emergence of system stray capacitance. A harmonic analysis is further discussed along with evaluation of transformer design comparisons. The experimental results show the performance of the DAB-based converter in bidirectional operation and improved common mode current generation with respect to EMI emissions. The simulation and experimental results have been performed using a 5kW rated power DAB-based converter with SiC power semiconductors.

A Hybrid Symmetric Cascaded H-Bridge Multilevel Converter Topology

This paper presents a hybrid symmetric cascaded multilevel converter capable of generating nearly twice the number of output levels as that generated by a conventional symmetric cascaded H-bridge multi-level converter. In the proposed converter topology, each phase comprises one five-level transistor-clamped H-bridge power cell, and the remaining are three-level H-bridge power cells, with all the power cells having equal cell dc-link voltages. Because of the cascade connection of the power cells with equal dc-link voltages, the H-bridge power cells share equal power and is nearly equal to the power shared by the transistor-clamped power cell. The near-equal power sharing condition further helps in effective suppression of the lower-order harmonics present in the input source current waveform if a suitable phase-shifting transformer is employed at the converter input. In this paper, the operating principle and the modulation strategy for the generalized configuration of the proposed topology is explained in detail. The analysis of the capacitor voltages in transistor-clamped H-bridge power cell and converter power loss calculations are also presented. To investigate the performance of the converter system, detailed simulation studies are carried out and the results are validated through experimental results obtained from nine- and thirteen-level laboratory prototypes.