Single Ended Primary Inductance Converter Research Articles

Experimental evaluation of global maximum power point techniques under partial shading conditions

Shading plays an important role in the operation of photovoltaic (PV) systems, especially when one of the cells or modules in the string is submitted to lower irradiance levels due to partial shading (PS). As a result of this condition, the cells or modules absorb the power generated by the unshaded parts, thus causing hot spots that can irreversibly damage the device. In order to mitigate this problem, bypass diodes (BDs) are often connected in parallel with the cells or modules to limit the reverse voltage and the power loss as a consequence. However, the occurrence of multiple peaks in the power versus voltage (P-V) curve is observed. Although conventional maximum power point tracking (MPPT) algorithms are successfully used when PV arrays operate under uniform irradiance conditions, they may fail to determine the global maximum power point (GMPP) if PS comes to occur. Considering that several MPPT algorithms for the operation under PS have been proposed during the last few years, this work presents a detailed analysis of some techniques dedicated to global maximum power tracking (GMPPT), aiming at defining which one presents the best performance. A dc-dc single-ended primary inductance converter (SEPIC) associated with microprocessor ATmega328P is employed to track the GMPP and assess the operation of each technique experimentally. The performance of the well-known perturb and observe (P&O) algorithm is also evaluated under PS condition for comparison purposes.

A PFC Based EV Battery Charger Using a Bridgeless Isolated SEPIC Converter

Conventional power factor correction (PFC) circuits in electric vehicle (EV) battery chargers have the efficiency limitation due to high conduction loss associated with a diode bridge rectifier (DBR) at the input. To mitigate this issue, a bridgeless (BL) single ended primary inductance converter (SEPIC) with improved power quality, is presented in this article. The input current shows a unity power factor operation over the entire charging duration. Due to elimination of DBR and the current conduction through relatively less number of devices, conduction losses are significantly reduced. This, in turn, improvises the charger efficiency as compared to conventional BL SEPIC converter. The overall performance of proposed charger is illustrated with the help of various operating modes, design equations, simulation-based performance and experimental validation under steady state as well as over wide fluctuations in ac mains voltage. The EV battery is charged at constant current/ constant voltage control mode, which provides satisfactory results for improved efficiency and inherent PFC, thus, improving overall performance of the charger.

Mitigation of Commutation Current Ripple in the BLDC Motor Drive Based on DC-DC Converter Using PR Compensator

Abstract Mitigation of commutation current ripple (CCR) in the brushless direct current (BLDC) motor drive using DC-DC converter based topologies are achieving widespread popularity. However, undesired alternating current (AC) components are presented in the DC-link voltage across the capacitor of the DC-DC converter which leads to a destabilization of the power supply during the commutation interval. In addition, undesired speed regulation and audible noise occur which deteriorates the motor performance. In order to encounter this problem, different conventional compensation techniques based on the low-pass filter (LPF) has been proposed. However, LPF requires a close relation between dynamic coupling and active compensation. In view of the limitation, this paper proposes a proportional-resonant (PR) compensator to stabilize the DC-link voltage. Performance of the PR compensator is tested on a combination of modified single-ended primary inductor converter (MSEPIC), DC-link voltage selector circuit is used in the proposed current ripple mitigation technique for BLDC motor drive. The PR compensator is utilized to stabilize the DC-link voltage whereas the DC-link voltage selector circuit is employed to achieve a regulated DC voltage from the MSEPIC converter for efficient current ripple suppression during the commutation interval. Simulation and experimental results verify the effectiveness of the proposed compensation scheme for current ripple mitigation technique of BLDC motor drive. The simulation and experimental results clearly reveal that the PR compensator effectively stabilized the DC-link voltage, which alleviates the CCR.

High Gain Single Ended Primary Inductor Converter With Ripple Free Input Current for Solar Powered Water Pumping System Utilizing Cost-Effective Maximum Power Point Tracking Technique

This paper presents a new configuration of high gain (HG) single ended primary inductor converter (SEPIC) with a ripple-free input current to maximize the efficiency of the PV panel for standalone water pumping system (WPS). The ripple eliminating circuit combined with the HG SEPIC converter to achieve reduced ripples in photovoltaic (PV) current is independent to the duty cycle control and hence, it can be easily integrated to the main power circuit of configuration. This circuit does not need any active switches, control, or drive circuit for its execution. The ripple eliminating circuit yields a complete removal of the electrolytic capacitor connected across the PV array and significantly reduces the inductance of the HG SEPIC converter. It also improves the response and power density of the dc–dc converter. The large gain of dc–dc converter enables the use of low-voltage PV panel and minimizes the partial shading and parasitic capacitance effects on PV array source. Due to the substantial compatibility between natural characteristics of switched reluctance motor (SRM) drive and WPS, a four-phase SRM drive is utilized in the proposed scheme. In addition, a single current sensor based maximum power point tracking technique is utilized in the proposed system, which helps to reduce the cost and improve the accuracy of the overall system. Analytical, simulated, and experimental results of the developed system are presented to demonstrate the performance of the system.

Analysis of Power Electronic Converters for Electric Vehicle Applications

this work presents a performance analysis of various power electronic converters with RL load to reduce the total harmonic distortion. The power converters inspected are: ZETA converter, single-ended primary inductance converter, often written SEPIC converter and Z SOURCE converter. The objective is to analyze which power electronic converter exhibits less total harmonic distortion (THD) and more efficiency in order to select the suitable converter for electric vehicle propulsion system. Three above mentioned converters are designed, modeled, and simulated. The zeta converter is advantageous over other converters inspected and have reduced total harmonic distortion, higher output power and hence improved efficiency. The simulations are done with MATLAB/SIMULINK and the results are presented.

Fuzzy Logic Controlled SEPIC Re-Lift Converter System - A Comparative Study

Voltage lift cascaded DC/DC converters are generally used to feed low power DC drives and batteries. This paper deals with the modelling, the simulation and the comparison of voltage lifted Single Ended Primary Inductor Converter (SEPIC) cascaded soft switched converter systems. The objective of this work is to improve the voltage gain and the efficiency of the voltage lifted SEPIC converter. Auxiliary switch with capacitor clamping is added in order to obtain the soft switching. SEPIC in self-lift and re-lift modes are simulated and the corresponding results are presented. The performance of the converter is studied in terms of output power and ripple voltage. Design and simulation results are presented in order to identify a cascaded system with high power output. The comparative study is presented in order to demonstrate the reduction in the ripple in the output voltage. The advantages of the proposed converter are high voltage gain, reduced switching loss and low electromagnetic interference (EMI). The open loop systems with fluctuating input voltages are simulated. Closed loop systems with proportional integral controller and Fuzzy Logic Controller (FLC) are simulated and their results are compared. Comparing the results, it can be observed that the time response has been improved in terms of settling time and steady state error.

Modified single‐switch bridgeless PFC SEPIC structure by eliminating circulating current and power quality improvement

In this study, a modified single-switch bridgeless power factor correction (PFC) single-ended primary-inductor converter (SEPIC) structure is proposed. The major practical drawbacks of the existing structure are the presence of circulating current and high maximum current stress at the input capacitor and line diodes. Therefore, to overcome these problems, the existing structure is restructured by repositioning the line diodes in series with input inductors. Besides, the principle of design parameters optimisation is used based on the balancing energy compensation between input capacitors and output inductor. This structure is designed to operate in discontinuous conduction mode in order to achieve almost a unity power factor. The operation principle and design consideration of the modified structure is introduced in details. The experimental results demonstrate that the total harmonic distortion current is reduced from 56.3 to 4.9% after the optimisation process is performed, and at the same time the dead zones are inherently eliminated. Furthermore, it is shown that the output voltage ripple frequency is always double from the input line frequency of 50 Hz and the output voltage ripple is constantly lower than the maximum input voltage ripple. Thus, the designed parameters of the experimental converter are verified with ∼160 W of the converter output power.

High-Performance Active-Clamped Isolated SEPIC PFC Converter With SiC Devices and Lossless Diode Clamp

An isolated active-clamped single-ended primary-inductor converter (SEPIC) power factor correction (PFC) converter based on SiC devices is presented. The impact of the resonant inductance on the switch voltage stress and range of zero-voltage switching is analyzed. Analytical expressions for the operating points of the switches over the line cycle are derived and used to evaluate the switching loss. Resonant inductance and snubber capacitance are chosen based on the analysis to reduce the switching loss without overstress of the switches. Lossless diode clamp circuits are designed for the output diode so that the peak voltage and extra losses due to device parasitics-induced oscillation are significantly reduced. The analysis is validated with a 2-kW single-phase PFC rectifier module with a peak efficiency of 96.56% at the 200-kHz switching frequency, total harmonic distortion (THD) < 2%, and power density of 58 W/in3.

Intelligent Control of a Photovoltaic Pumping System

This paper presents the application of the Adaptive Neuro Fuzzy Inference System (ANFIS) to track the maximum power of a photovoltaic generator that feeds a motor-pump group unit through a Pulse Width Modulation (PWM) inverter powered by a Single Ended Primary Inductance Converter (SEPIC) installed in the laboratory. The ANFIS control is trained in different temperatures and irradiances and the maximum power point tracking system varies automatically the duty cycle of the SEPIC converter. The performance of the MPPT controller is tested in simulations in Matlab/Simulink.

A Fast GMPPT Algorithm Based on PV Characteristic for Partial Shading Conditions

Photovoltaic (PV) modules experience some partial shading conditions (PSC) due to some various factors. In that kind of a condition, a few maximum power points (MPPs) possibly appear on the power-voltage (P-V) curve, which increases the tracking difficulties. It is known that maximum power point tracking (MPPT) may not be realized by hill climbing (HC) based conventional MPPT algorithms under PSCs. In this context, this paper presents a novel micro converter based algorithm that was developed by using P-V characteristics of PV modules. Unlike voltage or duty ratio scanning techniques, this paper introduces a new deciding method to determine the correct global MPP (GMPP) region. For this, the proposed method uses some duty ratios that were calculated corresponding to each MPP region. Thus, the initialization of duty ratio is done properly, which results in high tracking speed and accurate tracking of the GMPP. The other advantages of the proposed algorithm are structural simplicity, less computational burden, and ease of implementation with a basic microcontroller. The simulation results show that this algorithm has fast tracking capability and it manages to track GMPP for PSCs correctly, since it includes an artificial scanning procedure. Single ended primary inductance converter (SEPIC) is built in order to validate the proposed global maximum power point tracking (GMPPT) algorithm. The performance of the proposed GMPPT technique is verified by experimental studies. The results show that the proposed GMPPT technique is fast by up to five times than an adaptive full scanning strategy and improved IC algorithm. Furthermore, the proposed algorithm can be commercially used in micro converters, since it is compatible with small number of bypass diodes in a module.

Sliding Mode Control of the Isolated Bridgeless SEPIC High Power Factor Rectifier Interfacing an AC Source with a LVDC Distribution Bus

This paper deals with the analysis and design of a sliding mode-based controller to obtain high power factor (HPF) in the bridgeless isolated version of the single ended primary inductor converter (SEPIC) operating as a single-phase rectifier. In the work reported here, the converter is used as a unidirectional isolated interface between an AC source and a low voltage direct current (LVDC) distribution bus. The sliding-mode control is used to ensure the tracking of a high quality current reference at the input side, which is obtained from a sine waveform generator synchronized with the grid. The feasibility of the proposal is validated using simulation and experimental results, both of them confirming a reliable operation and showing good static and dynamic performances.

A Novel High Voltage Gain Noncoupled Inductor SEPIC Converter

In this paper, a novel noncoupled inductor high voltage gain single-ended primary-inductor converter (SEPIC) is presented. The proposed converter has various advantages, such as lower voltage stress on the switches, noninverting output voltage, high efficiency, and high voltage gain. Also, the introduced converter has a continuous input current which makes it suitable for renewable energy and fuel cell applications. Moreover, high voltage gain is achieved without using any transformer and coupled inductor, thus there is not any voltage overshoot for the switches during the turn- off process. This effect allows low conduction losses by using lower voltage rating switches and also additional clamping circuit is not needed. The control system of the presented converter is simple and the converter can be easily controlled in continuous conduction mode mode operation. Because, the gating pulses for both of the switches are the same and wide output voltage range is achieved only by changing the duty cycle. Furthermore, the number of the components compared to the other noncoupled inductor, SEPIC-based converters which provide near voltage gain to the proposed converter, is reduced. The detailed operation of the introduced converter and design considerations are discussed. Experimental results are presented to verify the performance of the proposed dc–dc converter.

Bridgeless PFC single ended primary inductance converter in continuous current mode

This paper presents bridgeless single ended primary inductor (SEPIC) converter operated in continuous conduction mode (CCM). The converter used in the study offers a lesser conduction loss compared to the other bridgeless SEPIC converter. In order to regulate the required output current and output voltage with high efficiency while achieving high power factor correction (PFC) at the input side, average current mode control (ACMC) is applied. The model is simulated using MATLAB/Simulink and it is found that the converter and the proposed control strategy provide a promising result. The preliminary results obtained from the experimental test-rig shows a good agreement as in simulation. The theoretical analysis of the proposed controller is verified on an output 100V to 300W prototype.

Correction: C. Anuradha; C. Sakthivel; T. Venkatesan; N. Chellammal. Analysis of Non-Isolated Multi-Port Single Ended Primary Inductor Converter for Standalone Applications. Energies 2018, 11, 539

The authors wish to make the following corrections to their paper [...]

Single‐phase hybrid discontinuous conduction mode SEPIC rectifiers integrated with ladder‐type switched‐capacitor cells

In this study, a set of new single-phase pulse-width modulation (PWM) Single-ended primary-inductor converter (SEPIC) rectifiers are proposed, which integrates conventional SEPIC rectifier, three-state switch (TSS) and switched-capacitor (SC) concepts. A conventional ladder-type SC cell is modified so that it can be integrated with the SEPIC rectifier operating in discontinuous conduction mode. The set of new single-phase PWM SEPIC rectifiers are able to provide: (i) lower-voltage stress on the semiconductors; (ii) higher-output voltage; and (iii) a split-capacitor output voltage. The structure employs a TSS and three different implementations are proposed. Two of them are bridgeless versions, which can provide higher efficiencies. Hence, the proposed structures can support using the SEPIC rectifiers as step-up in many applications and thus it can broaden its field of use. The topologies and their topological states, a theoretical steady-state analysis, a theoretical analysis of the ladder-type SC cell integrated with the SEPIC rectifier, a dynamic model for the control and a design example are discussed herein. Furthermore, a 500 W prototype with a 220 V input voltage, two 200 V split-output voltages, 400 V total output voltage and 50 kHz switching frequency was designed to corroborate the theoretical study.

Analysis and design of IMC-PI Controller with faster set point tracking and disturbance rejection for Interleaved DC-DC SEPIC converter based Power Factor Correction

This paper deals with the internal model controller (IMC) - proportional integral (PI) controller for interleaved DC-DC single ended primary inductance converter (SEPIC)-based power factor correction (PFC). The transfer function of the proposed converter exhibits seventh order dynamics with complex right hand plane (RHP) poles and zeros. IMC-based PI controller is used to achieve perfect control since it contains the internal model of the process implicitly or explicitly. The cascade control strategy is implemented for the proposed converter with IMC-based PI controller as inner current and outer voltage controller. The dynamic and steady state performance parameters of the proposed scheme are evaluated using MATLAB/Simulink software. The simulation results reveal that the proposed scheme offers excellent stability characteristics, robustness, faster set point tracking and disturbance rejection for various uncertainties in the process as compared to conventional PI controller.

An Energy-Efficient Implantable-Neural-Stimulator System with Wireless Charging and Dynamic Voltage Output.

Neural stimulators have become more and more widely used as an effective tool in neural therapies. To address power supply and consumption issues in this application, an energy-efficient Implantable-Neural-Stimulator system composed of a pulse generator and a wireless charger is proposed and implemented in 0.8μm 40V Bipolar-CMOS-DMOS (BCD) process. By adopting a Single Ended Primary Inductor Converter (SEPIC) and optimizing the switching frequency and the gate width of its power MOSFET, the stimulating output voltage range can cover 0~12V with a maximum output ripple of 0.31%. The proposed charger can charge the implantable battery wirelessly by an inductively coupled resonance circuit. In addition, it can adjust the charging voltage to keep it constantly only a little higher than the battery voltage, which reduces the charging headroom voltage and greatly improves the charging efficiency. The measured maximum power efficiencies of these two modules reach as high as 78.04% and 70.67%, respectively.

High‐voltage gain SEPIC‐based DC–DC converter without coupled inductor for PV systems

A new single-ended primary-inductor converter (SEPIC)-based DC-DC converter suitable for photovoltaic (PV) systems is introduced. The proposed converter has the advantage of continuous input current which reduces the input voltage ripple across the PV panels. Furthermore, it can provide a higher-voltage gain at smaller duty cycles when compared with counterpart SEPIC-based topologies which feature the absence of a coupled inductor. A smaller duty cycle for a given voltage gain translates to a lower-current ripple of the inductors, reduced conduction losses, and alleviated voltage stresses of the semiconductor switches. The proposed converter also benefits from a simpler structure and control scheme. The operational principles and the steady-state analysis are studied under both continuous conduction mode and discontinuous conduction mode. A comparative study between the proposed converter and seven counterpart topologies is also included. A laboratory prototype was built and tested. The experimental results are discussed in light of the theoretical analysis.

Intelligent tuned PID controller for wind energy conversion system with permanent magnet synchronous generator and AC-DC-AC converters

This paper presents the intelligent tuned PID controller-based Single Ended Primary Inductor Converter (SEPIC) for Maximum Power Point Tracking (MPPT) operation of Wind Energy Conversion System (WECS). As the voltage and frequency of the Permanent Magnet Synchronous Generator (PMSG) varies with the wind speed changes, Intelligent controlled SEPIC is utilized to maintain the constant DC link voltage. The intelligent tuned PID controller combines the advantages of both conventional and soft controllers. The 1.5MW variable speed WECS (VSWECS) with AC-DC-AC converter is developed using MATLAB/Simulink software. PMSG delivers a load/utility grid through an uncontrolled diode rectifier, intelligent controlled SEPIC and three phase inverter. The real time implementation of the proposed system is done by the DSP processor MSP430F5529. The performance of the SEPIC is tested in both simulation and experiment at different wind speed conditions. The performance of the proposed Intelligent MPPT control of SEPIC are compared with the conventional PID controller. Intelligent tuning of PID controller such as Fuzzy-PID, and ANFIS-PID is implemented in the proposed system and results are compared. The simulation and experimental results reveals that the proposed ANFIS method provide improved performance than the conventional PID method in terms of power quality.

A 1-MHz-Modified SEPIC With ZVS Characteristic and Low-Voltage Stress

A 1-MHz-modified single-ended primary-inductor converter (SEPIC) circuit is presented in this paper as an LED driver for automotive headlights. On the basis of traditional SEPIC, only a diode and two capacitors are added; therefore, the circuit structure is relatively simple and the volume is relatively small. High step-up capability is obtained with moderate duty cycle. Compared with traditional step-up circuit such as boost, low-voltage stress is gained which is beneficial to device selection. Zero-voltage switching is achieved at the same time to reduce switching loss. Planar inductors are used with the advantages of low profile and good thermal characteristic. Operational principle and parameters design process are introduced in detail. A 36-W prototype has been designed to demonstrate theoretical analysis. Obtained efficiency was up to 90.91% at full load.