Conventional Single-ended Primary Inductor Converter Research Articles

Investigation of a power factor correction converter utilizing SEPIC topology with input current switching

The single-ended primary-inductor converter (SEPIC) is a popular converter topology that can be employed in diverse application fields where the needed output voltage is greater or lesser than the input voltage. The non-inverted output voltage of a SEPIC converter provides additional advantages when compared to a buck-boost or Ćuk converter. Furthermore, the position of the capacitor in the SEPIC converter provides inherent isolation and circuit safety. One drawback in the conventional bridge-diode SEPIC AC-DC converter is the lack of controllability which can be overcome by adding extra active switch(es) or by replacing the passive diode(s) with active switch(es). However, introducing more active switches increases the control complexity and may increase the requirement for additional driver circuits. To address this trade-off, this article proposes a single-phase AC to DC modified SEPIC converter with input current-switching capability without adding any extra active switch(es). The existing active switch of the DC-DC SEPIC converter was shifted towards the input side and thus no additional switch has been introduced. This allows the option of input-current switching without any additional complexity in the control or driver circuit. The circuit topology, principles of operation, and ideal voltage gain equations for the suggested circuit have been derived and included in this research work. The proposed circuit has been simulated in both open-loop conditions and closed-loop control with varying duty cycles and output load. Results from the simulation show that the proposed converter provides better efficiency (∼90 %) and lower total harmonic distortion (THD) (10 %) for varying duty cycles when compared to a conventional converter. The converter also shows good dynamic response. A low-power 15V hardware prototype has been built to experimentally validate the performance of the proposed converter. Experimental results illustrate that the suggested converter can improve the power factor by up to 0.968 while operating at an efficiency above 75 %. This converter topology can be suitable for applications where high output voltage gain, high power factor, and lower THD are needed without isolation requirements.

Contribution to the Development of a Smart Ultrasound Scanner: Design and Analysis of the High-Voltage Power Supply of the Transmitter

A smart ultrasound scanner plays an important role in the transition to point-of-care imaging. DC–DC bipolar converters are essential in the generation of the ultrasound burst signal as they power the piezoelectric transducer. The conventional bipolar converter has minimal output gain and high-voltage stress, and the longer duty cycle on the semiconductors produces high conduction losses and reduces the efficiency of the system. The transmitter supply voltage is minimal, necessitating the use of high-gain bipolar converters. This proposed study is concerned with the development of an improved high-output voltage gain symmetric bipolar DC–DC converter topology which may be suitable for applications such as powering a smart ultrasound scanner transmitter. The proposed converter combines the conventional single-ended primary inductor converter (SEPIC) with a voltage multiplier cell (VMC) to improve voltage gain, transistor duty cycle, efficiency, and reliability. The present study describes the working principle of the proposed converter. The analysis of the voltage gain is carried out in continuous current mode (CCM) and discontinuous current mode (DCM), taking into account the nonidealities of the device. The simulation of the proposed system is carried out in the numerical environment Matlab/Simulink in order to verify its characteristics. A prototype model is realized and the experimental study presented validates the theoretical arguments and simulations. Due to the advantages of continuous input current, self-balancing bipolar outputs, and small component size, the proposed converter is a suitable choice for smart ultrasound transmitters.

A Bidirectional Charger for Low-Voltage-Powered Battery Vehicles

A battery charger with bidirectional operability for a low-voltage battery-powered vehicle is discussed in this work. A notable advantage of the presented charger is the effective performance with a wide output voltage range. Hence, this charger facilitates the user to charge a 48 V battery-powered vehicle as well as a 120 V battery-powered vehicle from a single-phase AC supply. Keeping this in view, the presented battery charger utilizes a modified single-ended primary inductor converter (SEPIC) as the back-end DC/DC converter. The modified SEPIC has significantly improved bidirectional operation with a wide voltage ratio of the output voltage and the input voltage. Hence, it effectively regulates the battery current of both a 48 V battery-powered vehicle and a 120 V battery-powered vehicle. Unlike the conventional SEPIC, the modified SEPIC utilizes switches with identical ratings. Thus, the manufacturing complexity reduces. Performance verification is carried out through the experimental analysis of the designed battery charger on a 1.1 kW hardware setup in the laboratory environment. The effectiveness of the battery charger is tested amid diverse operating conditions. Moreover, the conduct of the battery charger during the vehicle-to-grid (V2G) operation is discussed. Lastly, a comparison of the modified SEPIC with its counterparts, based on operational features, is made.

Performance numerical evaluation of modified single-ended primary-inductor converter for photovoltaic systems

<span lang="EN-US">Single-ended primary-inductor converter (SEPIC) was considered a good alternative to a DC-DC converter for photovoltaic (PV) systems. The SEPIC converter can operate with an input voltage greater or less than the regulated output voltage, or as a step-up or step-down. As a step-up converter, SEPIC boosts PV voltage to specific levels. However, gain limitation and voltage stress continue to reduce the efficiency of conventional SEPIC converters. Because of this, researchers created a modified SEPIC converter to improve performance. In this paper, six modified SEPIC converters were compared and evaluated. To compare fairly, all modified SEPIC converters are non-isolated and use a single switch. Power simulator (PSIM) software was used to simulate each converter with a BISOL BMO-250 PV module and maximum power point tracking (MPPT) P&O controller. The converter with the highest static voltage gain and lowest duty cycle has been identified. It results in up to ten times voltage increment with a 0.8-duty ratio. All topologies have the same voltage stress, with maximum and minimum values of 30.1 and 29.5 V, respectively. On the other hand, each topology produces different average efficiencies, with the highest and lowest efficiency at 99.5% and 97.2%, respectively.</span>

A three‐level isolated dc‐dc SEPIC converter with parallel‐connected output

AbstractThis paper presents a comprehensive theoretical analysis and experimental results for three‐level isolated dc‐dc converter based on the single‐ended primary‐inductance converter (SEPIC) topology. The main advantage of this structure is the reduction of voltage stress on semiconductors comparing it to the conventional SEPIC converter. Voltage stress is the major challenge associated with the conventional SEPIC structure, and contributions in this area can extend the range of applications for the family of SEPIC converters. The analyzed structure contains two switches, and their commands can be either equal or phase‐shifted by 180°. This provides four different modes of operation in discontinuous conduction mode (DCM), which have different operating stages, waveforms, and design equations. In this paper, the topology with parallel‐connected output and the static and dynamic theoretical analysis in DCM, for the four command signal profiles, are presented. The advantages and disadvantages, control strategy, experimental results, and a comparative analysis with the conventional SEPIC converter are discussed. The dc‐dc SEPIC converter was verified by experimental results from a proof‐of‐concept prototype with 500 W rated power, 400 V input voltage, 120 V output voltage, and 50 kHz switching frequency. The converter achieved 94.72% efficiency at rated power.

Design and Implementation of Bridgeless AC/DC PFC Sepic Converter with Valley-Fill Circuit

The continuous requirement to improve power quality has motivated the proposal of several PFC circuit topologies. The conventional AC/DC SEPIC has increased conduction loss due to the presence of bridge rectifier. In order to reduce the conduction loss and to improve the efficiency this research work deals with a bridgeless SEPIC (single ended primary inductance converter) AC/DC PFC integrated valley-fill circuit (VFC). The number of components is reduced compared to the existing topologies. The bridgeless topology results in reduced conduction loss, reduced current stress and improved system performance compared with the traditional SEPIC and the existing topologies. The circuit configuration of the suggested topology has been simulated using MATLAB/SIMULINK. The functional parameters of the projected AC/DC integrated VFC is compared with the conventional SEPIC (Con-SEPIC), con-SEPIC integrated VFC and bridgeless SEPIC in terms of passive component count, output voltage ripple, input current ripple, supply power factor, Total Harmonic Distortion. From the simulation outcomes, it is concluded that the bridgeless topology provides high power factor, reduced ripple and reduced supply current harmonics. The results are validated.

Steady State Behavior of a Single-Switch Non-isolated DC-DC SEPIC Converter Topology with Improved Static Voltage Gain

This paper presents the analysis of steady state behavior of a single switch non-isolated Single Ended Primary Inductance Converter (SEPIC) topology for achieving high DC voltage gain using diode-capacitor voltage multiplier. A voltage boosting module consisting of inductor and capacitor in addition with two diodes is introduced in the conventional SEPIC configuration in order to derive the DC-DC conversion technology proposed in this work. The voltage gain of the converter is extended using a diode-capacitor voltage multiplier cell. The converter suggested in this work has a single controlled switch. Hence, the conduction losses and the control complexity of the switch are very much reduced. The open loop configuration of the proposed non-isolated converter is described under continuous inductor current mode. The voltage boosting capability of the presented converter is compared with that of the existing modified SEPIC structure. The presented positive output converter topology has low switch voltage-current stress compared to the existing modified SEPIC topology given in the literature. The inductor and capacitor components of the suggested converter are so chosen that the DC output voltage and current waveforms show very low percentage of ripples. A DC voltage level of 24 V is given as input to the proposed converter. The DC voltage obtained across the load terminals is around 370 V which is achievable with low duty ratio (= 0.7) of the active switch. The voltage conversion ratio is very much influenced by the variation of the duty cycle of the power switch. In this work, the converter topology is presented and its various modes of operation are explained with equivalent circuits. The PSIM software platform is effectively and efficiently utilized to validate the performance of the converter. The obtained results convey that the proposed DC-DC conversion technology with extended voltage gain has the capability to maintain the steady-state output voltage and current profiles with almost negligible amount of ripples owing to the use of suitably designed non-dissipative elements in LC filter.

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.

Design of coupled inductors using split winding scheme for bridgeless SEPIC

A bridgeless single-ended primary inductance converter (SEPIC) is a highly preferred single-stage front-end AC–DC converter for applications requiring a wide variation of DC voltage because it also gives improved performance in terms of the quality of supply current. This study presents the design of coupled inductors for the bridgeless SEPIC using the split winding scheme. With coupling incorporated the required value of self-inductances of the input and output inductors for the same performance is reduced. Also, they can be wound on the same core, thereby resulting in a reduction in size. The conventional method of tuning the coupling coefficient by adjusting the air-gap is tedious. A split winding scheme for the distribution of windings over three limbs of E-core for obtaining the desired coupling coefficient is presented. The split winding scheme for the design of coupled inductors for bridgeless SEPIC converter rated for 500 W, 20 kHz is illustrated. The effect of coupling on the volume, weight, cost, and efficiency of the converter is compared with the conventional SEPIC converter without coupling for a similar performance. The performance of the proposed converter is evaluated using MATLAB/Simulink simulation and experimental results with a laboratory prototype rated for 500 W.

Experimental investigation of PV based modified SEPIC converter fed hybrid electric vehicle (PV‐HEV)

SummaryThis paper presents a high gain modified three‐port dual boost single‐ended primary‐inductor converter (SEPIC) converter operated hybrid photovoltaic (PV)/battery electric vehicle to improve the power transfer capability and efficiency of the power conversion stage. The proposed three‐port dual boost high gain SEPIC converter accepts wide voltage range of input then the conventional single stage SEPIC converter. The three‐winding high frequency coupling transformer integrates the two input sources and step‐up the input voltage. The theoretical and experimental analyses are presented to validate the performance of the proposed modified SEPIC converter in boosting the wide range of input voltage. A 6 kW, 12 to 600 V of experimental model has been developed and tested. The efficiency obtained from the designed model is around 94.11%.

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.

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.

Wide-range dimmable LED lighting based on QL-SEPIC converter

ABSTRACTThis paper proposes quadratic-like single-ended primary inductance converter (SEPIC) converter, a DC/DC converter suitable for wide-input voltage range. This circuit can be gated at higher duty ratio compared with conventional SEPIC converter, while the voltage conversion ratio is low. This feature is beneficial for high-input voltage because it prevents the controller from falling into extremely low duty ratio limitation. A prototype circuit is implemented with Pulse-Width-Modulation (PWM) control to drive the Light emitting diode (LED) strings for demonstration of the circuit application. Recent studies have advocated LEDs as efficient and durable technology for lighting applications. A stabilized output converter is required to regulate the current flowing through the LED lamp. The dimming control of the LED light output is implemented by the controller. This converter can be powered from either a 24-Vdc battery or from the universal AC input voltage (up to 360 Vdc). Such a wide-input voltage application can be found in emergency lighting in which the light is possibly powered either from battery or AC input voltages. Experimental results prove the feasibility of the circuit topology and theoretical analysis.

Modified Bridgeless SEPIC Rectifier for Power Factor Correction with Reduced Switch Stress Operating in Continuous Conduction Mode

In this paper, a high performance single-phase modified bridgeless AC–DC converter with reduced switch voltage stress for power factor correction (PFC) is introduced. The proposed converter is based on a single-ended primary-inductance converter (SEPIC) to meet the demands of PFC to unity and output voltage regulation. To reduce the number of components, the input bridge is combined with the SEPIC converter since the conventional SEPIC PFC is suffering with high conduction losses. It offers many advantages, such as fewer semiconductor devices in current flowing path which lead to improve the thermal management, low stress on each component, improved efficiency, high power factor compared to classical converter. Detailed analysis and design equations of the converter are presented. Simulation and experimental results are discussed for a 300[Formula: see text]W prototypeunder the universal input voltage (85–235[Formula: see text]V) to validate the performance of the converter.

Modelling, design and stability analysis of an improved SEPIC converter for renewable energy systems

ABSTRACTIn this paper, a detailed modelling and analysis of a switched inductor (SI)-based improved single-ended primary inductor converter (SEPIC) has been presented. To increase the gain of conventional SEPIC converter, input and output side inductors are replaced with SI structures. Design and stability analysis for continuous conduction mode operation of the proposed SI-SEPIC converter has also been presented in this paper. State space averaging technique is used to model the converter and carry out the stability analysis. Performance and stability analysis of closed loop configuration is predicted by observing the open loop behaviour using Nyquist diagram and Nichols chart. System was found to stable and critically damped.

MODELLING AND SIMULATION OF ANFISBASED MPPT FOR PV SYSTEM WITH MODIFIED SEPIC CONVERTER

This paper presents modelling and simulation of artificial neuro-fuzzy inference system (ANFIS)-based maximum power point tracking (MPPT) algorithm for PV system with modified SEPIC converter. The conventional existing MPPT methods are having major drawbacks of high oscillations at maximum power point and low efficiency due to uncertain nature of solar radiation and temperature. These mentioned problems can be solved by the proposed adaptive (ANFIS)-based MPPT. The proposed work involves ANFIS and modified single ended primary inductor converter (SEPIC) to extract maximum power from PV panel. The results obtained from proposed methodology are compared with other MPPT algorithms such as perturb and observe (P&O), incremental conductance (INC) and radial basis function network (RBFN). The improvement in voltage rating of modified SEPIC is compared with conventional SEPIC converter. The result confirms the superiority of the proposed system.

An isolated bridgeless AC-DC PFC converter using a LC resonant voltage doubler rectifier

ABSTRACTThis paper proposed an isolated bridgeless AC–DC power factor correction (PFC) converter using a LC resonant voltage doubler rectifier. The proposed converter is based on isolated conventional single-ended primary inductance converter (SEPIC) PFC converter. The conduction loss of rectification is reduced than a conventional one because the proposed converter is designed to eliminate a full-bridge rectifier at an input stage. Moreover, for zero-current switching (ZCS) operation and low voltage stresses of output diodes, the secondary of the proposed converter is designed as voltage doubler with a LC resonant tank. Additionally, an input–output electrical isolation is provided for safety standard. In conclusion, high power factor is achieved and efficiency is improved. The operational principles, steady-state analysis and design equations of the proposed converter are described in detail. Experimental results from a 60 W prototype at a constant switching frequency 100 kHz are presented to verify the performance of the proposed converter.

A Modified Bridgeless Converter for SRM Drive with Reduced Ripple Current

<p>Single Phase Switched Reluctance Motor is more popular in many industrial purposes for high speed applications because of its robust and rugged construction. For low cost and variable speed drive applications SRM are widely used.Due to doubly salient structure of motor, the torque pulsations are high when compared to other sinusoidal machines. The major drawback in using SRM drive is torque pulsations and increased number of switching components. In order to overcome these drawbacks, a bridgeless Single Ended Primary Inductor Converter (SEPIC) is proposed. The major advantages of this converter are continuous output current,smaller voltage ripple and reduced semiconductor current stress when compared to the conventional SEPIC converter. The ripple free input current is obtained by using additional winding of input inductor and auxiliary capacitors. To achieve high efficiency, active power factor correction circuits (PFC) are employed to precise the power factor. Further, the unity power factor can be obtained by making the input current during switching period proportional to the input voltage is proposed. The proposed system consists of reduced components and it is also capable of reducing the conduction losses. The working principles and the waveforms of proposed converter are analyzed. To analyze the circuit operation, theoretical analysis and simulation results are provided. Finally, the comparison between the waveforms of conventional SEPIC and proposed system is presented by using MATLAB/Simulink tools.</p>

A DC-DC converter topology for multiple-input photovoltaic configurations

The voltages generated from renewable sources, such as wind and solar energy, often vary because of environmental changes. When the input voltage drops to a value lower than that of the battery, it will fail to recharge. Cascaded buck-boost converters are conventionally used to step-up or step-down the input voltage, but these are relatively complex and costly. This paper describes a new battery charging system based on a non-inverting buck-boost converter. The proposed two-switch converter requires one less inductor and capacitor compared with the conventional SEPIC (single-ended primary inductor converter) to achieve the non-inverted output voltage. The model is validated through simulation results from one and multiple sources with constant and variable input voltages. Test results show stable operating performance under both steady-state and transient conditions. A maximum power point tracking algorithm is successfully applied to the proposed multiple input converter configuration. The system is suitable for both low-voltage portable charging devices and grid-connected photovoltaic/battery systems.

Analysis and Design of Single Phase AC-DC Modified SEPIC Converter

Power electronic devices with front-end rectifier are widely used in industry, commerce and transportation, which result in low power factor. Though there are several proposed solutions to this, Single Ended Primary Inductance Converter (SEPIC) converter was the most successful one. But the conventional SEPIC converters suffer from high switching losses. Hence in this paper, a modified SEPIC converter is used to improve the power factor at the mains side. This paper presents the simulation and analysis of single phase single-switch, converter topologies of AC-DC SEPIC converter and modified SEPIC converter for Continuous Conduction Mode (CCM) of operation with 48V, 100W output power. The results of SEPIC converter and modified SEPIC converter are compared for closed loop analysis in simulation which is done in PSIM. It is found that modified SEPIC converter has high regulated output voltage and high power factor.