Proposed Converter Topology Research Articles

Design and verification of a low-power AC/DC converter

Abstract This paper deals with the development and experimental verification of a low-power AC/DC converter. The proposed solution is aimed at the sub 0.5 W output power domain, commonly encountered in applications such as always-on wireless sensing nodes. To implement the proposed converter topology, a prototype application specific integrated circuit was designed and manufactured in a high voltage 0.35 µm CMOS technology, able to handle the maximum voltage of up to 120 V. The proposed design was first analyzed by transistor-level simulations showing high power efficiency and low no-load consumption of the developed converter. To facilitate experimental verification and measurement, an printed circuit board with the necessary external components was developed, as the available technology is unable to handle the AC line voltage directly. While the developed converter operated well with decreased input AC voltage, reliability issues arose during operation with the full AC line voltage of 230 Vrms. These are linked to digital control circuitry of the implemented chip and could be addressed in the second manufacturing run in the future.

Analysis of a High Step-Down DC/DC Converter Topology with a Single Inductor

This paper presents a novel high step-down dc/dc converter topology with a single inductor for 48V data center applications. Distinguished from conventional dc/dc converter topologies with a single inductor, the proposed converter topology is designed by series connecting a step-down cross-connected Fibonacci converter with a buck converter. By combination of these converter modules, the proposed converter topology offers a high voltage gain, viz. 1/48×, without cascade connection. Hence, high power efficiency is provided by the proposed single inductor topology. The characteristics of the proposed converter topology are investigated by theoretical analysis, computer simulations, and experiments. In the given theoretical analysis and the performed simulations, the proposed converter topology demonstrates higher power efficiency than the conventional converter topologies with a single inductor. Furthermore, the validity of the proposed topology is confirmed by the experiments.

Quasi‐Z‐source ‐based bidirectional DC‐DC converters for renewable energy applications

This article presents a design, analysis, and implementation of a novel impedance-source-based bidirectional DC-DC converter. The proposed converter employs an impedance network to the existing dual-active-bridge (DAB) circuit. It inherits all the advantages of the DAB converter along with extra benefits. Compared with the traditional isolated DC-DC converter, the proposed converter improved the boost ability of the converter. Also, the converter can withstand the shoot-through phenomenon in an H-bridge, improving the reliability. The converter can work in the normal buck/boost DAB mode when extra boost is not required. The bidirectional feature is inherent along with soft switching capability. It is therefore well-suited for the applications, where wide range of voltage gains are required such as renewable energy systems. The topological configuration and control strategy of the proposed topology in both operational modes are discussed. Simulation and experiments have been carried out to demonstrate the effectiveness of the proposed converter topology. The peak efficiency 97% was observed at the rated load of 500 W.

Novel high voltage gain dc–dc converter with dynamic analysis

This study proposes a non-isolated dc–dc converter based on a coupled inductor and switch-capacitor–boosting techniques. The goal of the proposed topology is to increase the voltage gain with low-duty cycle, so voltage stresses are decreased across power switches and diodes. The power switches are controlled by pulse width modulation. The common ground of input and output of the proposed converter makes it suitable for many applications such as photovoltaic systems. The proposed converter topology is discussed in continuous and discontinuous operation modes. A dynamic analysis of the proposed converter is also provided. Simulation and experimental verifications are presented to prove the effectiveness of the proposed topology.

High-Gain Switched-Capacitor DC-DC Converter With Low Count of Switches and Low Voltage Stress of Switches

This paper presents a novel concept of a high-voltage-gain DC-DC converter. The converter is made up of switched capacitors and passive resonant branches. A significant reduction in the count of switches and low voltage stress on the switches is achieved in this proposed converter topology, in comparison to that of a classical SC series-parallel converter. It is essential from the cost, volume, and efficiency of the converter standpoint. The reduction in the count of switches is threefold. The highest voltage stress on the switches depends on the output voltage and is decreased in the proposed converter as well, as the output voltage is divided into two series-connected capacitors. The presented results demonstrate the operation of the converter with the use of resonant branches, its switching strategies, voltage stresses of switches, efficiency, voltage gain, and output voltage regulation as well as the zero-voltage switching (ZVS) operation. The paper also presents novel issues related to analytical loss modeling, extended concepts of topology, converter start-up, and operation during transient states. The demonstrated concept of the converter, the analytical discussion and its design, as well as the experimental setup and results clearly demonstrate the optimization achievements.

Active DC‐link balancing and voltage regulation using a three‐level converter for split‐link four‐wire system

The integration of the distributed generation to the unbalanced loads or the grid requires a three-phase four-wire inverter. The three-phase four-wire inverter could be of three-leg or four-leg topology. However, both the topologies have their drawbacks. The three-leg inverter topology with a split capacitor suffers from poor DC link voltage regulation and poor DC link voltage utilisation. The four-leg inverter topology suffers from poor electromagnetic compatibility. To solve these problems, the split link inverters with active balancing capabilities are studied by many researchers. The split link inverter with an active balancing inverter requires a constant DC link voltage and has less flexibility regarding the variation of the DC link voltage. In this study, a new converter topology is proposed, which provides the controllable DC link voltage to split link inverter with active balancing capability and also reduces the voltage stress to semiconductor switches to half DC link voltage. The detailed description of the proposed converter topology, design of the controller, and control hardware-in-the-loop verification are presented in this study.

Energy transmission control for a Gridconnected modern power system Non-Linear loads with a Series Multi-Stage Transformer Voltage Reinjection with controlled converters

The effective way of energy transmission plays a key factor in improving the overall transmission systems efficiency. Many methods are proposed to control the reactive power flow, voltage fluctuations and power factor improvement, The proposed converter topology gives a much significant improvement in transmission systems performance which includes multistage transformers control with the controlled converters along with the series active filters. The overall control strategy which involves the Multistage Voltage Re-Injection Transformer Controlled Converters (MSVRITCC) to reinject the voltages into the grid to compensate the voltages and remaining parameters and power flow control. The proposed topology improves the grid security, flexibility in reaching the desired load requirements with grid adaptability and reduces THD values into a significant values and made the control of power conditioning circuit flexible and easy to perform the voltage compensations in grid to load connected applications. The binary control is used to trigger the power converter circuits which made the controlling much simpler.

A modified inverter topology for fault-tolerant direct torque control induction motor drive

ABSTRACT A modified fault-tolerant voltage source inverter-fed induction motor drive to maintain normal operation during open-circuit or short-circuit of power devices is proposed. The proposed inverter topology consists of a single capacitor at dc-link to eliminate the voltage-balancing issue in conventional fault-tolerant topology and a boost converter at the front end of inverter to operate the drive in full-rated condition during post-fault operation. Current control technique for boost converter and direct torque control for induction motor drive is implemented. The proposed topology reduces the stator current THD, torque and stator flux ripple when compared with the conventional fault-tolerant topology. Analysis of the proposed converter topology, modelling, simulation and experimental results are presented and also compared with the conventional fault-tolerant topology to highlight the eminence of the proposed scheme.

A Performance of a Novel Three Port Converter for Solar PV Storage Systems

This research work is generally emphasize to show and estimate the performance of a new three port converter by connecting a a battery port ,PV port, and also load port all collectively connect in a power system then a original three port converter named bidirectional buck with buck boost converter is projected. The chief advantage of the proposed converter topology is the one-stage power conversion which improve the overall success of the converter. The presentation of the proposed system is simulated in MATLAB and its efficiency based on overall module count, losses and competency is evaluated. Finally to validate the performance of the proposed converter, it is compared with other conservative converters and the evaluation results confirm the dynamic performance of the proposed system. The comparison of various power converters with MPPT technique are made and the simulation result proves the necessity of a suitable converter to be accepted for tracking the highest PowerPoint in solar PV systems.

Isolated three-port DC–DC converter employing ESS to obtain voltage balancing capability for bipolar LVDC distribution system

A bipolar low-voltage DC (LVDC) distribution system used in residential and building applications requires AC–DC converters and voltage balancers that balance the two DC bus polarities. The bipolar DC bus voltage level only relies on the voltage balancer tied with the AC grid. An isolated DC–DC converter for an energy storage system (ESS) with the voltage balancing capability is proposed to prevent the bipolar voltage level collapse caused by the failure of the grid-tied voltage balancer. The proposed converter topology is an enhanced three-port dual-active-bridge (DAB) converter which can balance the bipolar DC voltage level without complex control. Furthermore, it has less current stress in power switches than that of the conventional three-port DAB converter. The effectiveness of the proposed converter is verified with a 3-kW prototype converter.

Analysis and design of single‐stage, two‐mode AC/DC converters for on‐board battery charging applications

On-board battery chargers (OBCs) offer the feasibility of charging electric vehicles or plug-in hybrid electric vehicles with a standard household power supply. In this study, an OBC using two-mode topology (step-up or step-down) is presented. One of the main concern with two-mode topologies is the hard transitions of the converter operating from boost mode to buck mode or vice versa, which can deteriorate the performance of converter. This study provides smooth transitions between the modes and can have an output that could be more or less than the peak of input voltage. The detailed analysis of operating modes involved in the converter are analysed in the study. Moreover, the stress analysis on the components is also detailed in this study and the results are compared with existing two-mode converters. A simple dual-loop control structure with the proposed modulation technique eliminates the sub-harmonic oscillations and stabilizes the output voltage is also presented in the study. Experimental validation is performed for a 1.0 kW laboratory prototype and the results obtained are detailed in the study. This proposed converter topology can be applied as a single-stage OBC or as a power factor correction converter with variable DC link voltages in isolated two-stage OBC.

A Magnetic-Linked Multilevel Active Neutral Point Clamped Converter With an Advanced Switching Technique for Grid Integration of Solar Photovoltaic Systems

Nowadays, the grid-connected solar photovoltaic (PV) system has been drawing significant attention due to the rapid development and the decreasing cost of solar panels. The efficiency and reliability of a grid-connected PV system mainly depend on the power conversion system and the control strategy. This article presents a new magnetic-linked 7-level active neutral point clamped (ANPC) converter, which requires less number of flying capacitors and also reduces the control complexity of the grid-connected PV system. The proposed converter topology utilizes the input dc bus voltage better than the traditional ANPC multilevel converter and also provides galvanic isolation to the grid-connected PV systems. The lack of galvanic isolation is one of the biggest problems faced by the power frequency transformerless grid-connected PV systems. The proposed magnetic-linked power converter is also validated through simulations in MATLAB/Simulink and through tests in a laboratory test platform.

Inherently Non-Pulsating Input Current DC-DC Converter for Battery Storage Systems

With an ever-growing number of batteries being integrated into the electric grid, bidirectional converters with non-pulsating dc input current are required to replace the existing bidirectional converters so as to extend the lifetime of such dc power suppliers. Bidirectional DC-DC converters are increasingly used in a variety of applications including uninterruptable power supplies, electric vehicles and renewable energy systems. In this study, we propose a new topology of bidirectional dc-dc converter with inherently non-pulsating input current (NPIC), which is intended to be used for battery energy storage systems. With simple modifications from the conventional converters, the proposed NPIC converter has no inherent pulsating input current in the step-down (buck) mode under both continuous and boundary conduction modes (CCM and BCM), whereas in the step-up (boost) mode, the proposed NPIC converter retains the desired voltage gain. Underpinning theories, operating principles and steady-state performances are analyzed and presented in detail, which are then corroborated by simulation and experimentation. The proposed converter topology, with simple design principle and ease for implementation, is likely to have wide-ranging applicability in interfacing electrochemically functioned dc sources to modern power systems.

A New Modular Multilevel AC/AC Converter Using HF Transformer

This paper proposes a new modular multilevel AC/AC converter using high-frequency (HF) transformer, which has the advantages of modular design, easy expansion, high power density, no circulation current, good output voltage waveform quality and low cost. This converter has broad application prospects in the fields of high-voltage and high-power wind power generation, fractional frequency power transmission (FFTS) and power electronic transformer. The proposed converter topology can connect two three-phase AC systems with different frequencies and amplitudes directly. By introducing HF transformer, the direct series connection of input and output modules can be realized simultaneously, and the expensive industrial frequency transformer with large volume and weight can be removed. In order to achieve HF electrical isolation, the HF inversion of the output pulse is carried out at the inverter side to realize the HF output of the fundamental wave. After passing the HF transformer, the pulse is restored to the low-frequency output wave by the cycloconverter. Aiming at the problem of freewheeling of HF link, the method of common state conduction is introduced, which can effectively reduce the switching loss. The modulation scheme, control strategy and typical parameter design are developed. Furthermore, the feasibility of the proposed converter is verified by simulation results.

Experimental evaluation of direct torque-controlled 3-phase induction motor under inverter faults

ABSTRACTIn this paper, analysis and design of fault-tolerant converter topology for direct torque-controlled (DTC) induction motor (IM) drive suitable for low, medium and high power applications is proposed. The proposed converter topology can restore normal operation of the drive after the occurrence of open-circuit or short-circuit of power switches in the inverter. It consists of a current-controlled three-level boost converter (TLBC) to boost the dc-link voltage at input terminals of an inverter during post-fault, balance the voltages at dc-link capacitors and retains all the advantages of the conventional IM drive. Simulation and experimental results are presented for pre- and post-fault operation. The results are compared with conventional fault-tolerant DTC of the drive to highlight the merits of proposed converter.

Dynamic WPT system for EV charging with integrated energy storage

Wireless power transfer (WPT) can be used to charge electric vehicles (EVs) safely and efficiently. Dynamic wireless EV charging systems to charge EVs while moving has been developed but this technology is not yet widespread. One of the key challenges of dynamic charging is the pulsed nature of the transferred power, which may negatively impact battery life and the utility grid. Hybrid energy storage systems have been demonstrated as a potential solution, at the expense of a dedicated converter to interface with the energy storage element. This study presents a possible solution to the problem of adsorption and conditioning of high-power pulses, in the form of a novel converter topology that combines inductive WPT and super capacitor energy storage without the need for an additional converter stage. A suitable switching pattern is presented along with a steady-state mathematical model based on inductive power transfer, providing insight into the operation of the system. Experimental results of a prototype bi-directional WPT system are shown to validate the model and demonstrate the applicability of the proposed converter topology.

Multisource Switched Capacitor Based Boost Multilevel Inverter for Photovoltaic-Based Systems

In this paper, a multisource switched capacitor based boost multilevel inverter is proposed. The proposed topology features less number of components, high gain, self-charging capability of capacitors, reduced size of filter components. The modes of operation of the proposed converter and design guidelines of converter components are discussed. A comprehensive comparative study of the proposed converter topology with the topologies in the literature is given. Analytical expression for capacitor energy utilization (CEU) factor for the proposed topology is derived and the feasibility of the proposed converter with respect to CEU for the designed power rating is verified. The analytical performance of the proposed converter topology is verified through simulation studies. The common mode voltage and leakage current in the proposed topology are analyzed. Experimental prototype of the proposed converter topology with two sources and two capacitors for power rating of 500 W is developed and tested with resistive, inductive, and nonlinear loads. The experimental and simulated results are in close agreement with the analytical steady-state performance of the proposed converter.

Enhanced Buck-Boost dc–dc Converter with Positive Output Voltage

In this paper, a new transformerless buck-boost converter is presented. The voltage gain of the converter is higher than the classic boost converter, classic buck-boost converter, CUK and SEPIC converters. The proposed converter advantage is buck-boost capability. The proposed converter topology is simple; therefore, the converter control is simple. The converter has one main switch. Hence, the switch with low switching and conduction losses can be used. The stress of the main switch is low; therefore, switch with low on-state resistance can be selected. The principles of the converter and mathematic analyses are presented. The validity of the accuracy of calculations is verified by the experimental results.

A Non-Isolated Bridge-Type DC–DC Converter for Hybrid Energy Source Integration

The implementation of a non-isolated dual input bridge-type dc–dc converter for hybrid energy source integration is discussed in this paper. The proposed converter accommodates two sources using an inductor, a capacitor, two insulated-gate bipolar transistors (IGBTs) without the anti-parallel diode and two IGBTs with the anti-parallel diode. The different modes of operation of the converter are explained with detailed analytical waveforms and equivalent circuits. From the analysis, the steady-state output equation of the converter is derived. The boundary condition between the continuous conduction mode and discontinuous conduction mode operations is also derived. The dynamics of the converter is analyzed in detail with the help of a small signal model. The step response of different transfer functions is discussed. The computer simulations of the proposed converter topology have been carried out using MATLAB/Simulink. An experimental prototype of the proposed converter is also built and tested successfully in the laboratory environment. Performance comparison of the proposed converter is carried out with the conventional converter topologies in terms of component counts, efficiency, loss breakdown, and power density.

Modular multilevel converter with DHB energy‐balancing channels for medium‐voltage adjustable‐speed drives

This paper presents a modular multilevel converter (MMC) configuration that utilises energy exchange between submodules (SMs) of upper and lower arms, for energy rebalancing. The configuration is applicable to mediumvoltage high-power variable-speed drives with any number of motor phases, where the traditional MMC topology experiences challenging shortcomings. With the out-of-phase alternation of the fundamental ripple power in upper and lower arms, the proposed MMC configuration decouples this ripple power by employing dual half-bridge modules linking opposite SMs in upper and lower arms of the same MMC-leg. This counter-balances arm ripple-power through bidirectional power transfer between opposite SMs, resulting in a reduction in the SM capacitance and the MMC system stored energy. The proposed MMC configuration solves the problem of wide SM capacitor voltage fluctuation, especially at low operating frequencies, where the SM capacitor voltage ripple profile is almost constant, independent of the operating frequency. Therefore, the configuration is able to drive multi-megawatt machines from stand-still to the rated speed, at rated torque. The operation of the proposed converter topology is elucidated in detail, and its effectiveness is verified through simulation and experimentation.