Single Ended Primary Inductance Converter Power Factor Correction Research Articles

A High-Performance Isolated Bridgeless Resonant SEPIC PFC Converter at Medium Line Frequencies

Due to the characteristics of high power factor and low total harmonic distortion (THD) in discontinuous conduction mode (DCM), the power factor correction (PFC) converter based on isolated single-ended primary-inductor converter (SEPIC) is more suitable for medium-line-frequency avionics applications. However, the inherent defects of isolated SEPIC PFC converter such as the voltage-spike issue and the hard-switching operations of semiconductor components severely limit the utilization of such topologies. In this paper, a high-performance isolated bridgeless resonant SEPIC PFC converter is proposed. Instead of typical SEPIC-type operational mode, the proposed converter operates in resonant mode, and hence, all switches and diodes in this topology can achieve soft switching and the voltage-spike issue is effectively solved. Moreover, different from the existing isolated SEPIC PFC converters, the transformer in this topology can transfer energy through the whole switching cycle, which greatly improves the core utilization. The overall performance of the proposed topology is illustrated in terms of its working principles, control scheme and the parameter design considerations. Finally, the analysis is validated by a 400-Hz experimental prototype with soft-switching capability.

Bridgeless isolated sepic PFC for EV battery charging using ANN controller

The power quality of an Electric Vehicle (EV) battery charger is improved in this work using a bridgeless isolated single ended primary inductance converter (SEPIC). Owing to the excessive amount of conduction losses associated with the conventional Diode Bridge Rectifier (DBR) based Power Factor Correction (PFC) circuit; a Bridgeless circuit model is preferred in this work. The safe functioning of the PFC circuit is further ensured by selecting an isolated topology over a non-isolated converter topology. With the use of an artificial neural network (ANN) controller, the converter's operation is improved in terms of rising time, overshoot, steady state error and settling time. Distortions in the input current are curtailed with the aid of Hysteresis Current Controller (HCC). The entire work of the proposed converter in terms of design equations and several operating modes is detailed elaborately. The input current displays functioning with a unity power factor for the full charging period. The proposed Bridgeless Isolated SEPIC PFC's efficacy in improving the power quality of the EV charger system is determined using simulation results from MATLAB and hardware implementation utilising a DSP30F411 controller.

A Novel Variable On-Time Control Scheme for Boundary Conduction Mode SEPIC PFC Converter

Power factor correction (PFC) can be achieved by a single-ended primary inductor converter (SEPIC) operating in boundary conduction mode (BCM) with conventional constant on-time (COT) control, but it is challenging to achieve low total harmonic distortion (THD) and high-power factor (PF), particularly at high input voltage. A variable on-time (VOT) control strategy for BCM SEPIC PFC converter without input voltage feedforward and multiplier circuits is proposed to realize unity PF in this paper. By using a variable slope sawtooth generator whose slope is controlled by the duty cycle of the main switch to adjust the conduction time of the main power switch of the converter, the proposed VOT control scheme can use a simple and easy-to-implement circuit to enhance the PF and decrease the THD significantly, especially at high input voltage. The simulation model and 100W experimental prototype are built to verify the feasibility of the suggested control method. Simulation and experiment results demonstrated that the novel VOT control scheme remarkably enhances PF and decreases THD without affecting the efficiency by contrast with the conventional COT control.

Analysis of a new SEPIC AC–DC PFC converter for light emitting diode applications

Active power factor correction (PFC) converters are used to increase the power factor and improve the total harmonic distortion as a result of reducing the harmonics in the current. In this paper, a new bridgeless single-ended primary inductor converter (SEPIC) topology used in light emitting diode (LED) load is proposed to obtain near-unity power factor. By eliminating the input bridge in the bridge PFC converter, the total harmonics distortion is improved and a lower cost is obtained. The reactive power control is used to generate the reference current signal in the proposed converter to control the LED current. To demonstrate the applicability of the proposed topology and to compare its performance with the bridge SEPIC topology, PSIM circuit simulation was used, and an experimental prototype was performed. In the experimental study, 25 Vrms input voltage was applied, and 10 V DC voltage was obtained at the output. Using the proposed converter, the total harmonic distortion value was reduced from 5.722% to 1.837%, and the power factor was increased to 0.999. The experimental and simulation results showed that the total harmonic distortion value of the input current improved and that the proposed SEPIC PFC converter for low-power circuits, particularly in LED applications, is a very good option.

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.

Performance comparison and stability analysis of ACM and ENLC controlled SEPIC PFC converter

In this study, a detailed comparison between two power factor correction (PFC) controls, viz., average current mode (ACM) control and enhanced non-linear carrier (ENLC) control for single-ended primary inductance converter (SEPIC) are made. In ACM control, a linear current reference, generated using the conventional method is compared with the inductor current. In ENLC control, a non-linear carrier current reference, generated using passive components is compared with switch current. The proposed ENLC control uses reduced components and sensors compared to ACM and conventional non-linear carrier control methods. The evolving of nonlinear phenomena during load variation is investigated along with the electromagnetic interference (EMI) study with power spectral density estimation. For stability enhancement and EMI mitigation, a detailed simulation study is performed using MATLAB/Simulink platform. Mathematical bifurcation analysis, by deriving critical phase angle is carried out to obtain a better insight of stability boundaries in order to access the system behaviour. Owing to the advantages of ENLC, an experimental setup of ENLC controlled SEPIC PFC converter was built to support the results.

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.

Design and Analysis of a Repetitive Current Controller for a Single-Phase Bridgeless SEPIC PFC Converter

This paper studies a repetitive controller design scheme for a bridgeless single-ended primary inductor converter (SEPIC) power factor correction (PFC) converter to mitigate input current distortions. A small signal modeling of the converter is performed by a fifth-order model. Since the fifth-order model is complex to be applied in designing a current controller, the model is approximated to a third-order model. Using the third-order model, the repetitive controller is designed to reduce the input current distortion. Then, the stability of the repetitive controller is verified with an error transfer function. The proposed controller performance is validated by simulation, and the experiment results show that the input current total harmonic distortion (THD) is improved by applying the proposed controller for an 800 W bridgeless SEPIC PFC converter prototype.

An Improved Bridgeless SEPIC Converter Without Circulating Losses and Input-Voltage Sensing

In order to overcome the drawbacks of conventional bridgeless single-ended primary inductance converter (SEPIC) power factor correction (PFC) circuits, an improved bridgeless SEPIC PFC circuit is introduced by adding an additional output diode and an inductor. The undesired capacitive coupling loop and the circulating loss are removed. Thus, the high efficiency can be achieved. The operation principle and design consideration of the proposed converter are introduced in detail. Furthermore, a novel control method is employed to control the current continuous mode bridgeless SEPIC PFC circuit without input-voltage sensing. Meanwhile, the UCC28019-based modified hardware implementation circuit is designed and described. A 100-W prototype with 90–135 Vrms input line voltage and 60-V output voltage is built and tested. The corresponding experiment shows the validity of the proposed circuit topology and control strategy. A peak efficiency of 94% and power factor above 0.99 are achieved under 65-kHz switching frequency operation condition.

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.

Variable on‐time controlled boundary conduction mode single‐ended primary inductor converter power factor correction converter

A variable on-time (VOT) control strategy for boundary conduction mode (BCM) single-ended primary inductor converter (SEPIC) power factor correction (PFC) converter with high power factor (PF) and low total harmonic distortion (THD) is proposed. By utilising output voltage and input voltage to modulate the turn-on time of the switch of BCM SEPIC PFC converter, the unity PF and lower THD can be achieved. The operating principles of the VOT controlled BCM SEPIC PFC converter are analysed. The experimental results based on 100 W prototype demonstrate that the PF and THD of proposed VOT controlled BCM SEPIC PFC converter are better than those of traditional BCM SEPIC PFC converter.

A SiC-Based High-Efficiency Isolated Onboard PEV Charger With Ultrawide DC-Link Voltage Range

In LLC-based onboard battery charging architectures used in plug-in electric vehicles (PEV), the dc link voltage can be actively regulated to follow the battery pack voltage so that the LLC converter can operate in proximity of resonant frequency and achieve high efficiencies over the wide range of battery pack voltage. However, conventional boost-type power factor correction (PFC) converters are unable to provide ultrawide dc link voltages since their output voltages should always be larger than their input voltages. This paper proposes a Silicon Carbide (SiC)-based onboard PEV charger using single-ended primary-inductor converter (SEPIC) PFC converter followed by an isolated LLC resonant converter. With the proposed charger architecture, the SEPIC PFC converter is able to provide an ultrawide range for dc link voltage, and consequently enhance the efficiency of the LLC stage by ensuring operation in proximity of resonant frequency. A 1-kW SiC-based prototype is designed to validate the proposed idea. The experimental result shows that the SEPIC PFC converter achieves unity power factor, 2.72% total harmonic distortion, and 95.3% peak conversion efficiency. The LLC converter achieves 97.1% peak efficiency and always demonstrates a very high efficiency across the ultrawide dc-link voltage range. The overall efficiency of the charger is 88.5% to 93.5% from 20% of the rated load to full load.

A Unique SEPIC converter based Power Factor Correction method with a DCM Detection Technique

This paper presents a unique Single-Ended Primary Inductor Converter (SEPIC) based power factor correction method with discontinuous conduction mode detection. The SEPIC power factor correction (PFC) converter with the advent of digital control, powerful control techniques are used to achieve low-harmonic input current. An analog SEPIC based PFC converter is modified into a digitally controlled equivalent; thus provides flexibility for further implementations. The voltage and current sensing circuit design, compensator topology, the critical interrupt service routines, and the Digital Signal Processor (DSP) control is presented. The proposed SEPIC converter is contributes with a Discontinuous Conduction Mode (DCM) detection method using DSP for the purpose of power factor correction close to unity. The proposed detection technique has easy computation steps, and requires very small or almost null modification in existing SEPIC based PFC converters using DSP control techniques. The SEPIC-PFC converter analyse the effectiveness of the proposed detection approach over traditional detection techniques for power quality improvements. A new adaptive Mixed Conduction Mode (MCM) control technique is applies in the proposed SEPIC converter to realize optimal power factor and reduced total harmonic distortion contents in the output over a conventional controllers.

Closed Loop Analysis of Bridgeless SEPIC Converter for Drive Application

In this paper closed loop analysis of Single phase AC-DC Bridgeless Single Ended Primary Inductance Converter (SEPIC) for Power Factor Correction (PFC) rectifier is analyzed. In this topology the absence of an input diode bridge and the due to presence of two semiconductor switches in the current flowing path during each switching cycle which will results in lesser conduction losses and improved thermal management compared to the conventional converters. In this paper the operational principles, Frequency analysis, and design equations of the proposed converter are described in detail. Performance of the proposed SEPIC PFC rectifier are carried out using Matlab Simulink software and results are presented.

Modeling and PID Control of Single Switch Bridgeless SEPIC PFC Converter

This paper proposes the modeling of Single Ended Primary Inductor Converter (SEPIC) for Power Factor Correction (PFC) and PID control for the converter using various tuning methods. The SEPIC is capable of operating from an input voltage that is greater or less than the regulated output voltage. A small signal dynamic model for SEPIC PFC converter is obtained using state space averaging technique which provides a fifth order transfer function. The complete model of the converter is simulated using MATLAB (SIMULINK). Then the PID controller is designed for the SEPIC PFC converter and various tuning methods were adopted using SISO tool in MATLAB.

A Bridgeless SEPIC PFC Rectifier with Reduced Conduction Losses

A bridgeless single-ended primary inductor converter (SEPIC) power factor correction (PFC) rectifier is introduced in this paper. In order to maximize its efficiency more than a conventional bridgeless SEPIC PFC Rectifier, a new driving scheme is proposed. In the proposed converter, conduction losses are reduced by eliminating bridge diodes. In addition, the impedance of the return current paths is lowered and conduction losses are reduced by applying a gate-on signal which is maintained during half line cycle to inactive switches. Consequently, the conduction losses of the proposed converter are significantly reduced and high efficiency is achieved. Besides high efficiency, the proposed converter provides high power factor (PF) and a continuous input current. Input current ripple can be easily removed by a simple filter capacitor. The operational principles, steady-state analysis and design equations of the proposed converter are described in detail. Experimental results from a 130 W prototype at a constant switching frequency of 100 kHz are presented to verify the performance of the proposed converter.

Design and Implementation of a Photovoltaic High-Intensity-Discharge Street Lighting System

This paper presents a photovoltaic (PV) high-intensity-discharge (HID) street lighting system. A single-ended primary inductance converter (SEPIC) is studied for maximum power point tracking (MPPT) and battery charging. High conversion efficiency and high MPPT accuracy can be achieved under different atmospheric conditions. A pulse-current-charging scheme with an adaptive rest-period is also applied to avoid battery overcharging. An electronic ballast circuit is also designed to release the solar energy stored in battery for powering HID lamps. The studied PV HID street lighting system is connected to the ac-line utility with a SEPIC power factor correction converter. High input power factor can be achieved when energy is drawn from the ac-line utility to drive the HID lamp and to prevent the battery from over-discharging. The proposed PV HID street lighting system has the advantages of high power density, simple circuit, and long lifetime. The operating principle and design considerations were analyzed and discussed in detail. A laboratory prototype was implemented and tested. The experimental results were shown to verify the feasibility of the proposed scheme.

Modeling and simulation of a new Bridgeless SEPIC power factor correction circuit

A new Bridgeless PFC circuit based on Single-Ended Primary Inductance Converter (SEPIC) is proposed in this paper. The new topology has less component count and less conducted component during each mode of operation within one switching period. The small-signal and steady-state model of the circuit operated in Discontinuous Conduction Mode (DCM) is derived using the Current Injected Equivalent Circuit Approach (CIECA). The large-signal model based on state-space and switch model are also developed to verify the large-signal behavior. The simulation results of the proposed converter show that the output voltage of the proposed converter is successfully regulated to its desired value while the input current regulation is inherent.

Bridgeless SEPIC Rectifier With Unity Power Factor and Reduced Conduction Losses

In this paper, a new bridgeless single-phase AC-DC converter with an automatic power factor correction (PFC) is proposed. The proposed rectifier is based on the single-ended primary inductance converter (SEPIC) topology and it utilizes a bidirectional switch and two fast diodes. The absence of an input diode bridge and the presence of only one diode in the flowing-current path during each switching cycle result in less conduction loss and improved thermal management compared to existing PFC rectifiers. Other advantages include simple control circuitry, reduced switch voltage stress, and low electromagnetic-interference noise. Performance comparison between the proposed and the conventional SEPIC PFC rectifier is performed. Simulation and experimental results are presented to demonstrate the feasibility of the proposed technique.