DC Power Converter Research Articles

Super twisting approach of a higher order sliding mode controller for a flyback DC–DC converter in photovoltaic applications

SummarySolar photovoltaic (SPV) modules are frequently utilised to produce electricity. The output voltage and load power in SPV‐based applications are variable and strongly reliant on the operating conditions of solar energy, such as irradiance and ambient temperature. They offer additional challenges for the robust design of power converters, and DC–DC power converters provide the power bus with a constant voltage. Properties of a nonlinear system and load patterns necessitate a more robust control design for the power converter. This paper gives robust control of high‐order sliding mode (HOSM) control in isolated flyback converters for solar photovoltaic applications. The proposed HOSM technique is contrasted with the conventional PI control technique. The proposed HOSM control approach outperforms traditional PI control strategies under uncertainty and disturbance settings. This paper also presents a method for preventing chattering in flyback converters (FCs) using modified super twisting sliding modes.

Design of Integrated Simultaneous Information and Power Receiver for WIPT Application

This letter presents the design and fabrication of a multifunctional simultaneous information and power receiver (SIPR) considering a multitone time-modulated array as wireless information and power transfer (WIPT). The proposed SIPR with Wilkinson power divider delivers power to information processing and DC generating blocks. The fabricated SIPR receives information in horizontal and vertical polarizations. A voltage-doubler-type rectifying circuit is designed for DC generation with a microstrip line model for the lumped parameter. DC generating block generates a maximum of 76% RF to DC power conversion. Furthermore, the bit error rate (BER) performance graph supports the use of the receiver for the digital modulation schemes.

A new modulation strategy on isolated battery charger with wide input and output voltage range

AbstractA new wide voltage operation range isolated battery charger, which is composed of an asymmetric T‐type AC–DC power rectifier and a modified re‐configurable half bridge DC–DC power converter, is proposed in this paper. The asymmetric T‐type rectifier adopts different modulation strategies under different AC bus voltage amplitudes and different battery voltages for increasing power conversion efficiency. As the isolated DC–DC power stage, a modified re‐configurable half bridge converter applies a three‐winding transformer to achieve a wide output operation range. The proposed battery charger operates over a wide AC input voltage range and wide DC output voltage range. A 3.2 kW hardware battery charger prototype is built to adapt AC voltage between 85 and 265 V. Both constant current and constant voltage modes are implemented experimentally to charge the battery up to 6.5 A from 50 to 500 V. The experimental results prove that the proposed asymmetric T‐type rectifier adopts different modulation strategies under different AC bus voltage amplitudes and different battery voltages can increase the power conversion efficiency, the proposed DC–DC converter can output the DC voltage from 50 to 500 V and the proposed battery charger can achieve around 94% efficiency.

Automated Solar PV Simulation System Supported by DC–DC Power Converters

Solar photovoltaic simulators are valuable tools for the design and evaluation of several components of photovoltaic systems. They can also be used for several purposes, such as educational objectives regarding operation principles, control strategies, efficiency, maintenance, and other aspects. This paper presents an automated solar photovoltaic simulation system with the capability to generate automated tests considering different parameters of solar photovoltaic panels and different operation conditions. The proposed simulator is composed of three buck-boost DC–DC power converters controlled in such a way that will behave similarly to solar photovoltaic panels. It allows to introduce additional variable loads and maximum power point tracker algorithms similar to real systems. Some converters are controlled by a DSP microcontroller connected to a single programmable logic controller which generates the automated tests. Thus, using the presented solution, it is possible to implement the I-V and P-V characteristic curves of solar photovoltaic panels and evaluate different maximum power point tracker algorithms considering different meteorological conditions and load variations, being a useful tool to teach subjects related to renewable energy sources and related applications. Several simulation results using Matlab/Simulink and experimental results are presented to validate the operation of the proposed solution. Experimental results achieve a ripple between 2% and 5% of the desired average current in MPP conditions.

A Single-Stage Bridgeless Isolated AC–DC Conversion System for Light Electric Vehicles Charging Application

A 1- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\phi $ </tex-math></inline-formula> single-stage ac–dc power conversion unit employing bridgeless isolated modified single-ended primary inductor converter (BLIMSEPIC) is presented in this work for the light electric vehicles (LEVs) charger applications. Unlike the existing SEPIC and Cuk high-power factor (HPF) ac–dc converters, the presented BLIMSEPIC HPF ac–dc converter incorporates continuous input and output current features while operating under discontinuous current mode (DCM) condition. Therefore, it demonstrates excellent applicability in charging applications. The DCM operation considerably simplifies overall control architecture, as the presented BLIMSPEIC ac–dc converter exhibits inherent power factor correction capability under DCM operation, and therefore, significantly reduces the cost of control implementation. Besides, the continuous input and output currents attribute lessen the filter’s size and associated losses. Furthermore, the reduced voltage stress and zero current switching of semiconductor devices, together with the front-end bridgeless structure, considerably improve the conduction and switching losses of the charger. The operation, design, control, and performance of the BLIMSEPIC HPF ac–dc converter are experimentally verified, and corresponding results are presented to justify its efficacy for LEVs charging applications.

Experimental Validation of a Bidirectional Multilevel dc–dc Power Converter for Electric Vehicle Battery Charging Operating under Normal and Fault Conditions

This paper presents a bidirectional multilevel dc–dc power converter for electric vehicle (EV) battery charging. The operating principle of the power converter was presented, analyzed, and experimentally validated under normal and fault conditions. The topology under study was integrated into a bipolar dc grid through the split dc-link of the bidirectional multilevel dc–dc power converter. Considering the failures that can occur in the bipolar dc grid, i.e., in each wire of the bipolar dc grid (positive, negative, and neutral), it was experimentally verified that the dc–dc power converter ensures that the EV battery-charging process continues, regardless of the occurrence or absence of open-circuit failures. In light of this fact, the proposed control algorithms and the presented topology were validated through a set of considerable simulation and experimental results, analyzing the distinct states of the power semiconductors, which compose the bidirectional multilevel dc–dc power converter, for distinct conditions of operation. The developed laboratory prototype of the bidirectional multilevel dc–dc power converter for EV battery charging, which was implemented to obtain the experimental results, is described in detail in this paper. The experimental validation was carried out for the main different fault conditions in the bipolar dc grid in terms of open-circuit failures and, moreover, considering the steady-state and transient-state operations of the dc–dc power converter. The experimental analysis demonstrated that even in the presence of failures in the positive, negative, or neutral wires of the bipolar dc grid, the bidirectional multilevel dc–dc power converter guarantees the correct EV battery-charging operation.

Power Quality Diagnosis Due to Integration of Renewable Energy Source at Utility Grid

Article outlines hybrid energy sources for fulfil supply demand through proposed approach. The hybrid renewable energy sources generation capacity of 6 kW as solar power and 50 kW power as solid oxide fuel cell plant with storage system are interfaced to the DC bus in proposed paper for performance diagnosis on the basis of power demand as per utility load application by conversion of DC power to AC power and power quality of grid/load parameters collected on PCC, which affected by RE source integration at utility bus in terms of power quality parameters as per event ON/OFF grid mode. For this study design a two-bus test system, first bus is DC bus for integration of solar PV plant and solid oxide fuel cell power plant to generate hybrid DC power which convert to AC power by using inverter technology and deliver to the second bus of utility load bus in proposed test system for application of utility load as well as utility grid as per event proposed. A low pass LC filter is modeled to remove high frequency harmonics from the inverter output which is fed to grid as well as test system of utility network.

Average Current Mode Control of a DC–DC Boost Converter to Reduce the Decoupling Capacitance at the PV Array Output

Due to the full-wave AC–DC power conversion, second-order frequency oscillations of current and voltage are created in single-phase PV-grid-connected inverters. These oscillations propagate toward the input and adversely affect the PV power utilization ratio. Large power decoupling capacitors are the preliminary solution for coping with voltage ripples across PVs, and they decrease the lifetime of the overall system. This paper proposes the average current mode control (ACMC) of the input inductor in a DC–DC boost converter in a double-stage PV power conversion system. Through extensive explanations of the modeling and control of a DC–DC boost converter, it is shown that the ACMC reduces the propagation of the second-order frequency components (SOFCs) toward the input PV array. Two controllers—a proportional–integral controller and an integral single-lead controller—are considered to adjust the average value of the PV output current in a single-loop control structure. This control approach is simple to implement and exhibits high impedance to current oscillatory components, which, in turn, reduces the size of the required capacitance.

Design of control system for solar power generation based on an improved bat algorithm for an island operation

Abstract Solar energy is sustained using the principle of photovoltaic effect through a solar photovoltaic (PV) system as the main receiver of sunlight for the island. The use of photovoltaic (PV) systems to generate power from solar energy has increased in recent years due to its availability and sustainability. The proposed bat algorithm provides a very quick confluence and high accuracy since it interactively merges with the exploration advancements with the substantial distinctive signal search during the maximum power point tracking process from the PV array. The improved bat algorithm proposes a signal search method to increase the speed and tracks more power at a longer distance by using the signal between the bat and its prey. An energy storage system (ESS) stores solar energy and releases it into the system for use when energy generation from the source is low. DC to DC converter controls and regulates the output generated voltage from the PV array. DC to AC converter converts DC power produced to AC power to be supplied to the island for use. The design and simulation were performed in MATLAB Simulink and the result shows the effectiveness of the proposed design.

Bidirectional AC–DC Modular Multilevel Converter With Electric Spring Functions for Stabilizing Renewable AC Power Grid at the Distribution Voltage Level

Bidirectional ac–dc power converters are essential in emerging smart grids with increasing renewable energy penetration. This article presents a bidirectional ac–dc power converter system comprising modular multilevel converters (MMCs) and dual active bridges (DABs) with medium-frequency transformer isolation designed for linking an ac distribution voltage of 6.6 kV to a dc grid of 800 V for future electric vehicle (EV) charging infrastructure. The novel contributions include: 1) a modular method to power EV charging infrastructures in multistorey carparks without mains-frequency transformers and 2) the incorporation of a front-end control with electric spring (ES) functions that enable the dc power grid with battery energy storage to interact dynamically with the ac power grid at the distribution voltage level to achieve instantaneous power balance and hence system stability. The long-term aim is to use large EV charging infrastructures to stabilize increasing intermittent renewable energy via the proposed ac–dc converter, consequently accelerating the adoption of large-scale renewable energy and EV as a complementary solution to combat climate change. This article focuses on the bidirectional ac–dc converter of this overall idea based on the MMC and DAB technologies as an example. Results on the power converter operation level and ac microgrid level are included.

Nonisolated DC–DC Power Converter Synthesis Using Low-Entropy Equations

There is a growing demand for novel nonisolated dc–dc power converters with the deployment of dc power distribution systems integrating renewable sources and energy storing elements. The load and source of these applications have different input and output voltage levels, and it is vital to avoid operating the interfacing power converters at extreme duty ratios. Therefore, engineers and researchers explore the power converter synthesizing techniques since the mid-1970s, fulfilling the above requirement besides the nonpulsating input and output current. Among them, the analytical synthesis method has gained popularity, although it gives rise to high-entropy equations. This article shows a simple yet powerful topology synthesis method based on the low-entropy equations that reveal the connection between the energy storing elements and switches. To this end, a set of design rules have been introduced in this article to realize the voltage-second balance equations obtained by decomposing the voltage gain polynomial using design-oriented analysis. Moreover, different decomposition levels of the gain polynomial have been discussed to embed inductors at either input or output or both ports. Furthermore, the synthesis of multitopology converters using low-entropy equations has been demonstrated. The applicability of the proposed method is validated using motivational examples and using experimental results of the selected converters.

Single Phase T-Type Multilevel Inverters for Renewable Energy Systems, Topology, Modulation, and Control Techniques: A Review

Multilevel inverters (MLI) consist of a wide range of power converters. They have many designs and have been introduced with different circuit topologies such as neutral point clamped, diode clamped, cascaded H-bridges, and flying capacitors. Some of these MLIs have disadvantages, including design complexity, size, and losses due to the large number of switching devices required when they produce many output voltage levels. They are also bulky in size and may require several DC power sources. This paper presents a review of the various topologies of single-phase T-Type MLIs (T-MLIs). These MLIs are used to convert DC power from renewable energy sources (RES)” into AC with a near-sine waveform and low total harmonic distortion (THD). Simple and complex MLI designs are discussed. The major types of modulation techniques are discussed, including sinusoidal pulse width modulation (SPWM), selective harmonic elimination (SHE), and preprogrammed PWM. Various methods of output voltage control are taken into consideration as well. The aim of this comprehensive survey is to identify T-MLIs for researchers and those interested in the power conversion field, as well as to discuss the many topologies, identifying designs with superior characteristics that can be efficiently implemented with RESs to obtain better AC voltage with enhanced power quality.

Zero-Additional-Hardware Power Line Communication for DC–DC Converters

A power line communication (PLC) solution to provide a data link between two or more dc–dc power converters is proposed. The approach does not require additional analog circuitry or high-sample-rate analog-to-digital converters to be added on top of the original system. A modulation and signal injection method for the transmitter, and a sampling and demodulation strategy for the receiver are developed. The PLC frequency band is placed between the control loop cutoff frequency and the power electronics circuit cutoff frequency, in a region that we identify as the “intermediate frequency band”. The transmitter modulates the converter voltage or current output by injecting perturbations into the control loop at the input to the PWM unit. To tolerate unsynchronized transmitter and receiver clocks, a virtual zero-crossing location algorithm is combined with long/short pulse identification to achieve demodulation at the receiver. The solution is verified experimentally and achieves reliable bidirectional PLC communication at 2 kb/s with an 8 kHz receiver sampling frequency.

High step‐up MIMO DC–DC power converter control‐based pole placement

AbstractThis paper introduces a new high step‐up multi‐input multi‐output (MIMO) DC–DC converter control‐based pole placement suitable for photovoltaic system applications. The suggested topology has a high stability current control. Low element number, high voltage conversion ratio, and low ripple input current are the main advantages of the proposed converter. The capability to use several energy resources with different voltage/current characteristics, increase the number of inputs and outputs arbitrary without duty‐cycle limitation, and control each input unit power switch independently are other advantages. The operation principle of the suggested topology, steady‐state analysis in continuous condition mode (CCM), and parameter design are analyzed. A comparison between the suggested topology and other converters is applied. Two‐input two‐output version of the suggested topology in 200 W at an operating 50 kHz switching frequency is analyzed. Finally, the Typhoon HiL‐404 emulating setup is applied to verify the performance and efficiency of the suggested high‐step‐up MIMO DC–DC power converter.

A Virtual Impedance Enhancement Based Transformer-Less Active EMI Filter for Conducted EMI Suppression in Power Converters

Due to the successive switching actions in a power electronic system, considerable conducted electromagnetic interference (EMI) is generated. This has been a major concern in designing power converters, which requires additional EMI filtering efforts. Passive EMI filters are the most common solutions to EMI reduction but usually consume a large portion of the volume as well as weight in power converters. Active EMI filters (AEFs) or hybrid EMI filters (HEFs) are considered best candidates over traditional passive EMI filters to achieve higher power density in power converters. The utilization of current transformer to sense or to compensate the EMI noise can increase the volume of an AEF. In this article, a transformer-less AEF, sprung from the concept of virtual impedance enhancement, is proposed. The proposed design features feedforward control with current-sensing-voltage-compensating. The operation principle of the proposed AEF is thoroughly introduced, and its performance is evaluated through simulations and experiments. Experimental results with an ac–dc power converter and a dc–ac inverter show that the proposed AEF can be generally applied to reduce conducted EMI on either ac or dc power lines.

Integrated DC - DC converter design methodology for design cycle speed up

A novel design methodology, enabling extreme design cycle time speed up of DC - DC power converters, is developed. The concept is based on providing high accuracy post-layout RC parasitics aware results, by replacing complicated large RC netlists with small signal approximation models. Scattering parameters analysis is adopted for “on the fly” performance simulation of the power MOSFET switches' routings, which act as large passive linear networks. The RC parasitics aware back end of line (BEOL) S-parameter model is extracted and seamlessly integrated into the schematic testbench, considering the actual circuit as a black box and therefore actively cutting down the design's netlist size to minimum values. Thus, the DC – DC converter performance degradation, that previously could not be simulated, now is accurately predicted and evaluated while the respective simulation time and the number of design iterations needed from layout (physical design) to the schematic and vice versa, are minimized. The proposed methodology is validated using an Integrated Pulse Width Modulation controlled DC - DC converter product vehicle, for light energy harvesting applications, designed, simulated and fabricated in a 0.18 μm CMOS standard process. Experimental results confirm the accuracy and design cycle speed up effectiveness of the proposed novel IC power converter design methodology.

Admissible edge-dependent finite-time ℋ∞ filtering for discrete-time switched systems with average dwell time

Considering that the property of finite-time convergence is of great significance for practical filters, this article is focused on the finite-time ℋ∞ filtering for discrete-time switched systems with average dwell time. Different from the case of the general mode-dependent switching, the information of the admissible switching edge is fully exploited to derive more preferable filtering scheme. In order to further reduce the design conservatism, the multiple discontinuous Lyapunov function approach, which incorporates the concept of admissible edge-dependent average dwell time, is used to analyze the finite-time stability and ℋ∞ performance of the filtering error system. This approach assigns each subsystem of the error system with a discontinuous function rather than a continuous one, so it is less conservative compared to the conventional multiple Lyapunov function approach. First, the finite-time boundedness and ℋ∞ performance is analyzed for general switched nonlinear systems with admissible edge-dependent average dwell time. Then, a sufficient condition of the finite-time boundedness and ℋ∞ performance is derived for the filtering error system based on the obtained criterion. Subsequently, an admissible edge-dependent finite-time filtering scheme is proposed for the underlying system in terms of linear matrix inequalities. Finally, the proposed filter design scheme is applied to a DC–DC power converter circuit, and its effectiveness and superiority are verified by the simulation results.

Automatic Mitigation of Current Imbalance for m-Phase Interleaved LLC Resonant Converter

The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter offers a promising solution for dc power conversion. The input-parallel output-parallel system offers low specification switches to use in high power applications. Moreover, the interleaving of the converters reduces the requirement of input and output passive filters, providing better dynamic performance and higher power density. However, the tolerances in the designed resonant components and the unavoidable mismatch in the circuit parameters lead to unbalanced estimated tank gain characteristics. Consequently, the zero-voltage-switching is lost, a serious imbalance in currents appears, and a thermal runaway is likely to occur. The proposed method utilizes the existing magnetics of resonant inductors and self-alleviates the imbalance in the output, input, and tank currents without increasing active or passive components, dedicated balancing controls, and expensive sensors. A 4 kW four-phase prototype is tested during steady state, transients, and phase-shedding modes to validate the performance of the proposed method.

Performance Comparison of Numerical Methods in a Predictive Controller for an AC–DC Power Converter

The use of model-based predictive control in power converters has substantially increased in recent years. This control technique always needs a discrete system model to be implemented. There are several methods to obtain a discrete model; in this paper, all common methods are examined from a practical point of view. Their precision, simplicity, and implementation requirements are analyzed to establish their advantages and disadvantages. From this analysis, it is shown that different discretization methods result in different closed-loop converter performance. A model-based predictive control AC–DC converter is used to show that different discretization procedures result in different total harmonic distortion. For this evaluation, a simulation of a 1 kW three-phase active rectifier was performed in Matlab-Simulink.

Modeling and Design of Split-Pi Converter

High-power bidirectional dc–dc converters are being widely employed in renewable energy interfacing, energy storage, electric vehicle charging, military, aerospace, and marine applications. Among various bidirectional topologies documented in the literature for dc–dc power conversion, the split-pi converter invites special attention with regard to applications involving multi-phase systems requiring high-power density. This paper endeavors to present the small-signal modeling of the split-pi converter in its various operating modes. Subsequently, the dynamic characteristics of the converter are studied, and appropriate control design is presented for stable operation of the converter. Frequency response plots are illustrated, and a hardware prototype model of the converter is designed and implemented.