Single Ended Primary Inductance Converter Research Articles

Non‐isolated high step‐up/step‐down quadratic converter for light‐emitting diode driving

SummaryThis work presents an alternating current–direct current (AC–DC) single‐switch quadratic single‐ended primary inductance converter (SEPIC) for applications involving light‐emitting diodes (LEDs). The proposed topology is basically composed of two cascaded SEPIC stages, where the first one provides input power factor correction (PFC) and the second one allows obtaining power control (PC) for dimming purposes. It is also capable of providing high step‐up or step‐down without requiring the use of extreme duty ratios. A detailed qualitative analysis is derived, from which it is possible to obtain a consistent design procedure. Experimental results from a laboratory prototype are thoroughly discussed aiming at validating the theoretical assumptions.

GaN-Based ZVS Bridgeless Dual-SEPIC PFC Rectifier With Integrated Inductors

This article investigates the gallium nitride based bridgeless dual single-ended primary inductor converter (SEPIC) power factor correction (PFC) with full input voltage range zero-voltage-switching (ZVS) turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> for the application of step down ac–dc converter. The operation principle for the bridgeless Dual-SEPIC PFC and the theoretical analysis for the ZVS operation has been investigated. Furthermore, a new magnetic integration has been proposed to assemble all three inductors, including one input inductor and two output side inductors into one E-I-E core. The integrated inductor reduces the total ferrite volume and makes the converter more compact. The inductance design for ZVS SEPIC PFC and the magnetic reluctance modeling for the E-I-E core with the coupled inductor has been analyzed. The effective equivalent inductance of the input inductor can be implemented with a much less number of turns by a carefully designed coupling coefficient. Finally, a 300 W GaN-based MHz bridgeless dual-SEPIC PFC with the integrated inductors is developed and tested with full–range ZVS, 97% peak efficiency based on the ZVS extension strategy.

Fuzzy Logic-Based Duty Cycle Controller for the Energy Management System of Hybrid Electric Vehicles with Hybrid Energy Storage System

Due to increasing fuel prices, the world is moving towards the use of hybrid electric vehicles (HEVs) because they are environmentally friendly, require less maintenance, and are a green technology. The energy management system (EMS) plays an important role in HEVs for the efficient storage of energy and control of the power flow mechanism. This paper deals with the design, modeling, and result-oriented approach for the development of EMS for HEVs using a fuzzy logic controller (FLC). Batteries and supercapacitors (SCs) are used as primary and secondary energy storage systems (ESSs), respectively. EMS consists of the ultra-power transfer algorithm (UPTA) and FLC techniques, which are used to control the power flow. The UPTA technique is used to charge the battery with the help of a single-ended primary inductor converter (SEPIC) during regenerative braking mode. The proposed research examines and compares the performance of FLC with a proportional integral (PI) controller by using MATLAB (Simulink) software. Three scenarios are built to confirm the efficiency of the proposed design. The simulation results show that the proposed design with FLC has a better response as its rise time (2.6 m) and settling time (1.47 µs) are superior to the PI controller.

Design and Analysis of High-Efficient Driver Model for LED Luminaires

LED luminaires need a driver circuit for working properly. Most of the drivers have disadvantages such as losses during operation. This issue becomes more important while supplying with limited sources such as renewables. To overcome the problem, this study proposes a novel energy efficient driver for LED luminaires based on zero voltage switching (ZVS) single-ended primary inductance converter (SEPIC) technology. Driver and hence luminaires were designed to be fed from photovoltaic (PV) panels. In addition, an adaptive MPPT algorithm was developed to obtain optimum efficiency from supply system. SEPIC approach was preferred for MPPT application due to its advantages such as non-reversing polarity. This feature allows energy efficiency in corporation with ZVS. Proposed model was designed under PSIM platform with all components; PV panels, ZVS, SEPIC, and LED luminaires. A detailed analysis was performed by using system graphs under various operating conditions as different irradiance levels. Results show that proposed model is energy efficient and modular because of its low-volume structure. Therefore the model can lead smaller driver circuits with minimum losses.

Unified CACSD Toolbox for Hybrid Simulation and Robust Controller Synthesis with Applications in DC-to-DC Power Converter Control

The current article presents the design, implementation, validation, and use of a Computer-Aided Control System Design (CACSD) toolbox for nonlinear and hybrid system uncertainty modeling, simulation, and control using μ synthesis. Remarkable features include generalization of classical system interconnection operations to nonlinear and hybrid systems, automatic computation of equilibrium points for nonlinear systems, and optimization of least conservative uncertainty bounds, with direct applicability for μ synthesis. A unified approach is presented for the step-down (buck), step-up (boost), and single-ended primary-inductor (SEPIC) converters to showcase the use and flexibility of the toolbox. Robust controllers were computed by minimization of the H∞ norm of the augmented performance systems, encompassing a wide range of uncertainty types, and have been designed using the well-known mixed-sensitivity closed loop shaping μ synthesis method.

SEPIC converter of Automatic Power Factor Correction by improved traditional linear control

With increasing using of nonlinear electronic equipment at a wide range, total harmonics distortion (THD) in the line current has grown to be a considerable problem. The methods that include reducing harmonics in line current and power factor correction are required. Therefore, the essential target of this proposed work is to reduce the harmonics produced in the line current and improve the power quality of the load by the output voltage regulation and power factor correction (PFC). This paper presents a Single-Ended Primary Inductance Converter (SEPIC) at Discontinuous Conduction Mode (DCM) for automatic power factor Correction (APFC). The SEPIC converter is modeling by utilizing Current Injected Equivalent Circuit Approach (CIECA). The control system is applied by traditional linear control (TLC). The TLC has been modified by an optimization algorithm (OA) and adds an (inner or current). The proposed design of SEPIC-PFC is implemented by MATLAB and Simulink. According to the simulated dynamic behavior results, a unity power factor and 15% of total harmonics distortion (THD) reduction have been obtained comparing with previous work. Besides, a regulated DC output voltage has been achieved. The proposed control system has a low overshoot, small settling time, and steady-state error close to zero

Plotting Characteristic Curves of Photovoltaic Modules: A Simple and Portable Approach

This work presents a simple and low-cost curve tracer for the analysis of photovoltaic (PV) modules. The proposed system allows the plotting of current versus voltage (I-V) and power versus voltage (P-V) characteristics in a fast and straightforward approach employing a dc-dc single-ended primary inductance converter (SEPIC) topology. Thus, it is possible to obtain variable impedance seen from the PV source by properly adjusting the duty cycle imposed to the active switch and consequently, by plotting several points that accurately define the aforementioned curves. The curve tracer is analyzed through simulation and experimental tests while its performance is evaluated considering uncontrolled environmental conditions and also the eventual occurrence of partial shading.

A current sensor based adaptive step‐size MPPT with SEPIC converter for photovoltaic systems

Efficient maximum power point tracking (MPPT) is an important problem for renewable power generation from photovoltaic systems. In this work, a current sensor based MPPT algorithm using an adaptive step-size for a single ended primary inductance converter (SEPIC) based solar photovoltaic system is proposed. Due to lower sensitivity of power to current perturbation as compared to the voltage one, such a scheme is shown to yield better efficiency at steady-state. A new adaptation scheme is also proposed for faster convergence of the MPPT technique. Hence, the proposed scheme yields better transient as well as steady-state performance. A prototype converter is used along with digital implementation of the proposed MPPT technique to demonstrate the superiority of the proposed algorithm over the fixed step-size and voltage based ones. Simulation and experimental results corroborates the same.

Load voltage-based MPPT technique for standalone PV systems using adaptive step

This paper presents a load voltage based (LVB) maximum power point tracking (MPPT) technique using adaptive step-size (ASS) for standalone photovoltaic (PV) systems. The technique improves the convergence speed of the MPPT using a single voltage sensor to measure the load voltage (VL) regardless of the nature of load type. The ASS of the MPPT controller is varied according to the slope dVLdD of VL versus duty ratio (D) characteristic. The effectiveness of the proposed technique is tested for different insolation level conditions. This ASS based control scheme improves the convergence performance over fixed step-size (FSS) scheme under varying insolation condition. A single-ended primary inductance converter (SEPIC) is used for interfacing the PV system with the resistive load, which increases the operating range of the PV system. The tracking performance of the proposed technique is compared with FSS MPPT, perturb and observe (P&O) and incremental-conductance (IncCond) techniques by simulation. Experimental verification using a developed laboratory prototype is also carried out.

A DCM High-Frequency High-Step-Up SEPIC-Based Converter With Extended ZVS Range

A discontinuous conduction mode (DCM) high-frequency high-step-up single ended primary inductor converter (SEPIC)-based converter with extended zero voltage switching (ZVS) range is presented in this article. With the incorporation of some components on conventional SEPIC, the proposed converter achieves better performances such as high voltage gain, low voltage stress, and ZVS. The additional components form a resonant cell which enables the switches to work in ZVS, and switching loss is reduced accordingly. In order to achieve ZVS, the converter is designed to work in DCM. Due to inclusion of the resonance stage, traditional pulse width modulation (PWM) or pulse frequency modulation (PFM) control method is unable to regulate the output characteristics and maintain ZVS of the power switches at the same time. Therefore, a hybrid control method is proposed in this article to guarantee ZVS within a specific load range. According to this hybrid control method, the ZVS range is extended effectively. GaN switches and planar magnetic components are also used. Working principles and steady-state analysis are presented in detail. A 1-MHz 36-W prototype with 10 voltage gain has been designed to demonstrate theoretical analysis. Efficiency obtained is up to 91.8% at full load. Experimental results show good agreement with theoretical analysis.

A new approach in design of sliding-mode voltage-controller for a SEPIC

The non-linear structure and non-minimum phase nature of the single ended primary inductor converter (SEPIC) makes it difficult to achieve a robust performance under load variations. For this purpose, this paper presents a novel PI-based sliding mode control scheme combined with a modified sliding variable for a SEPIC operating in continuous current mode. The controller is designed based on the full order model of the converter and formulated using the Lyapunov theory and ensures the existence of the stability in the converter. Then, a linearized model of the controlled system is derived using an equivalent control technique. Unlike the traditional SMC methods and to guarantee the robustness and load disturbance rejection of the controller, a new optimization method is used to synthesize the controller parameters based on the output sensitivity analysis and thereby, the control sensitivity is minimized and the system performance is improved. The proposed controller results in a better performance in comparison with the traditional method. Simulations are presented to confirm the capability and effectiveness of the suggested strategy compared with the conventional method and experimental results are shown to validate the simulations.

Solar powered battery charging scheme for light electric vehicles (LEVs)

Abstract This work is targeted to design an economical and self-reliant solar-powered battery charging scheme for light electric vehicles (LEV’s). The single-ended primary inductance converter (SEPIC) is utilized to enhance the performance of solar power and battery charging at various solar irradiances. Various unique attributes of a SEPIC converter offer the effective charging arrangement for a self-reliant off-board charging system. Further, the continuous conduction mode (CCM) function of the converter minimizes the elementary stress and keeps to maintain the minimum ripples in solar output parameters. A novel maximum power point tracking (MPPT) approach executed in the designed system requires only the battery current to track the maximum power point (MPP) at various weather situations. Both the simulated and real-time behaviors of the developed scheme are examined utilizing a battery pack of 24 V and 100 Ah ratings. These responses verify the appropriateness of the designed system for an efficient off-board charging system for LEV’s.

A DCM Single-Controlled Three-Phase SEPIC-Type Rectifier

A discontinuous conduction mode (DCM) three-phase single-ended primary-inductor converter (SEPIC) is presented in this article. The analyzed converter operates as a high-power factor stage in AC–DC conversion systems. As its main features, it presents three controlled switches and a single control signal with simple implementation and low-current harmonic distortion. The converter topology, its design equations, and its operation modes are presented as well as a simulation analysis considering a 3 kW–220 V three-phase input to 400 V DC output converter. The experimental results are included, considering as an application the rectifier stage in low-power wind energy conversion systems (WECS) based on a 1 kW permanent magnet synchronous generator (PMSG) with variable voltage frequencies. From the analysis performed in the paper and the simulation and experimental results revealed, it is concluded that the converter is indicated to be employed in any AC–DC low-power conversion system, such as DC distribution systems, and distributed generation or hybrid systems containing variable-frequency generation.

Improved Controller and Design Method for Grid-Connected Three-Phase Differential SEPIC Inverter

Single-ended primary-inductor converter (SEPIC) based differential inverters (SEPIC-BDI) have received wide concerns in renewable energy applications due to their modularity, galvanic isolation, decreased power stages, continuous input current, and step up/down capability. However, its design still has several challenges related to component design, the existence of complex right half plane (RHP) zeros, and increased sensitivity to component mismatches. In this context, this paper presents an improved control and enhanced design method for the three-phase SEPIC-BDI for grid-tied applications. A generalized static linearization approach (SLA) is proposed to mitigate the low-order harmonics. It practically simplifies the control complexity and decreases the required control loops and sensor circuits. The mismatch between the SEPIC converters in each phase is highly mitigated due to the independent operation of the SLA in each phase and the output dc offset currents are reduced. The proposed enhanced design methodology modifies the SEPIC open-loop transfer function by moving the complex RHP zeros to the left half-plane (LHP). Therefore, a simple proportional-integral (PI) controller effectively maintains converter stability without adding higher-order compensators in the literature. Moreover, a straightforward integrator in the control loop eliminates the negative sequence harmonic component (NSHC) and provides a low computational burden. Simulations and experimental results based on 200V, 1.6 kW, 50 kHz prototype with silicon carbide (SiC) devices are provided to validate the effectiveness of the proposed work. The results show that the proposed controller and design method achieve pure output current waveforms at various operating points of the inverter and dc voltage variations.

Mitigation of Complex Non-Linear Dynamic Effects in Multiple Output Cascaded DC-DC Converters

In the modern world of technology, the cascaded DC-DC converters with multiple output configurations are contributing a dominant part in the DC distribution systems and DC micro-grids. An individual DC-DC converter of any configuration exhibits complex non-linear dynamic behavior resulting in instability. This paper presents a cascaded system with one source boost converter and three load converters including buck, Cuk, and Single-Ended Primary Inductance Converter (SEPIC) that are analyzed for the complex non-linear bifurcation phenomena. An outer voltage feedback loop along with an inner current feedback loop control strategy is used for all the sub-converters in the cascaded system. To explain the complex non-linear dynamic behavior, a discrete mapping model is developed for the proposed cascaded system and the Jacobian matrix’s eigenvalues are evaluated. For the simplification of the analysis, every load converter is regarded as a fixed power load (FPL) under reasonable assumptions such as fixed frequency and input voltage. The eigenvalues of period-1 and period-2 reveal that the source boost converter undergoes period-2 orbit and chaos whereas all the load converters operate in a stable period-1 orbit. The proposed configuration eliminates the period-2 and chaotic behavior from all the load converters and is also validated using simulation in MATLAB/Simulink and experimental results.

Analysis of a New Soft-Switched Step-Up Trans-Inverse DC/DC Converter Based on Three-Winding Coupled-Inductor

This article introduces a new nonisolated full soft-switching step-up dc/dc converter based on single-ended primary inductor converter (SEPIC) structure. The proposed topology utilizes a three-winding coupled-inductor (TWCI) to increase the voltage gain, but unlike other coupled-inductor-based converters, its voltage gain is increased by reducing its magnetic turns ratio. Moreover, the secondary and tertiary turns ratios of the TWCI can be used as an additional design freedom to extend the voltage gain, which indicates more converter flexibility. Due to the continuous input current, the proposed converter can be used for many types of renewable energy sources. Also, the leakage energy from the TWCI has further been recycled and transferred to the output with the help of a regenerative passive clamp circuit. Due to the soft-switching performance, the proposed converter has no switching losses at the turn- on instant for the power switch and reverse recycling losses of the diodes. Furthermore, the use of a small number of components along with the soft-switching performance offer high efficiency. Steady-state analysis and design considerations are discussed thoroughly. Finally, a 200-W prototype with 200 V output voltage is provided to verify the theoretical analysis.

PI-like fuzzy based synchronous SEPIC converter control for PV-fed small scale irrigation DC pump

For off-grid, standalone solar-fed water pumping has become a very viable option for small householder farmers. Appropriate configuration and control to suit this specific application are required. Buck, boost, and buck-boost converters are used to ensure impedance adaption between the solar PV generation and the load. However, these converters have switching harmonic problems. This problem is solved by the use of a single-ended primary inductor converter. Thus, a single-ended primary inductor converter is designed to overcome these drawbacks. Therefore, the objective of this paper is to design a single-ended primary inductive converter with a PI-like fuzzy controller. In this paper, synchronous SEPIC converter with PI-like fuzzy controller for PV-fed pumping system is modeled and designed. The system performance at different input conditions is evaluated. PI and PI-like fuzzy controllers have been compared using MATLAB/SIMULINK. PI-type fuzzy controller is less sensitive to input parameters variation than PI due to auto-tuning capability. Less than 2% output variation is recorded between 200 and 1000 W/m2 irradiance. This show that output voltage is less sensitive to the input solar radiation with this SEPIC converter control. The steady-state result obtained in speed and flow rate were 141.4 rpm and 1.56 l/s, respectively, and the voltage error was 1.4 V. Thus, PI-like fuzzy controller was used to reduce the steady-state error. The results obtained with PI-like fuzzy controller in speed and flow rate were 143.6 rpm and 1.624 l/s at 6 m head, respectively. The voltage error is 0.2 V which is less than the PI converter error (1.4 V).

A High-Performance Isolated SEPIC Converter for Non-Electrolytic LED Lighting

This paper proposes a high-performance isolated single-ended primary inductor converter (SEPIC) that is integrated with a non-dissipative snubber for a light-emitting diode (LED) driver. The proposed LED driver employs the snubber circuit to minimize any switching overvoltage caused by parasitic leakage inductance of the high-frequency transformer in the isolated SEPIC converter. This paper also presents a detail theoretical analysis of the proposed LED driver including its operating modes and design calculation. The experimental results of the proposed LED driver at the rated power of 18 W shows that it has a high-power factor, low harmonics, employs non-electrolytic capacitors, low switching stress, high reliability and high efficiency.

A Low Cost Front-End Converter With Maximum Power per Ampere for Rooftop Wind Turbines

Small Permanent Magnet Synchronous Generators (PMSGs) are widely used in small rooftop wind turbines. In order to inject the electric power generated by the PMSG, into the grid, a back-to-back AC/DC/AC converter is required. In this paper, a low cost with high efficiency converter is proposed for the rectifier stage to obtain the maximum power per ampere of PMSG. This structure based on Discontinuous Conduction Mode Single-Ended Primary Inductor Converter (DCM SEPIC) with a single power electronic switch, proposes a converter which is cost-effective and suitable for the small wind turbine used in residential applications. Furthermore, other advantages of the proposed converter include obtaining maximum power delivered per ampere using a simple control method and reducing the size of converter inductive filter by exploiting the PMSG internal synchronous reactance as part of the filter. Unlike the conventional DCM Boost rectifiers, the proposed converter has a continuous input current, which results in lower PMSG conduction loss. Operation principles and various operating modes of this converter are discussed in detail in this paper and verified by closed-loop simulation and experimental results for a 500W/200V prototype.

MODELLING AND CONTROL OF RURAL PV MICRO GRID USING FUZZY LOGIC CONTROLLER

This paper proposes an approach for the hybrid solar photovoltaic and Battery management for stand-alone applications. Battery charging process is non-linear, time-varying with a considerable time delay so it is difficult to achieve the best energy management performance by using traditional control approaches. A fuzzy control strategy for battery charging or discharging used in a renewable power generation system is analyzed in the paper. To improve the life cycle of the battery, fuzzy control manages the desired state of charge. A fuzzy logic-based controller to be used for the Battery SOC control of the designed hybrid system is proposed. This paper presents a general description of the implemented microgrid topology. The exact linearization theory adapted for power converters is applied to both a Single-Ended PrimaryInductor converter (SEPIC) to extract energy from PV modules and to a Boost converter to increase the voltage. The entire designed system is modeled and simulated using MATLAB/Simulink environment.