Showing papers on "Flyback transformer published in 2020"

A Hybrid Boost–Flyback/Flyback Microinverter for Photovoltaic Applications

Abstract: For photovoltaic applications, the flyback microinverter with pseudo-dc-link is popular as a simple topology but brings large transformer turns ratio and thus large leakage inductance, which would deteriorate the converter efficiency. To solve this issue, based on the nonisolated pseudo-dc-link structure, this paper proposed a hybrid boost–flyback/flyback (BF/F) microinverter. This new topology is operated at the BF mode for the most segment of a half grid cycle and the F mode for the rest. During the BF mode, high voltage gain with low voltage stress is easily available in minimized transformer turns ratio. Besides, the leakage energy is recycled and the turn- off voltage spike of the main switch is clamped, as a result of a passive snubber inherently contained in this mode. Given that the BF mode is lack of step-down function, the F mode is developed to regulate the output voltage even for values lower than the input voltage. The operation and characteristic of the hybrid BF/F microinverter in boundary conduction mode are analyzed in detail, and the mathematical expression of reference current is derived theoretically to guarantee high power quality. Finally, a 240 W prototype was implemented to validate the theoretical analysis and the benefits of the proposed topology.

Advances of Modeling and Reduction of Conducted and Radiated EMI in Flyback Converters

Abstract: Recent years have witnessed evolutions of topologies and applications of wide bandgap devices in flyback converters, in order to improve efficiency and power density. However, due to the increased topology diversity, and the increased high frequency noise, unprecedented EMI challenges are created. Those challenges lead to advances of EMI modeling and reduction techniques, to be generalized for different topologies, and to be effective at higher frequency ranges. The emerging flyback EMI challenges and research advances are analyzed in this paper. Future challenges and development of EMI in flyback converters are discussed.

Investigate and Reduce Capacitive Couplings in a Flyback Adapter With a DC-Bus Filter to Reduce EMI

Abstract: In consumer electronics, high power density power adapters are designed to minimize the adapter size. As a result, the components are getting very close and the near-field coupling issue tends to be severe. This compromises the performance of electromagnetic interference filters, especially at high frequencies. This article investigates near-field capacitive couplings and the reduction techniques in a high power-density power adapter with a dc-bus filter. The parasitic capacitive coupling theory is developed and parasitic coupling capacitances are experimentally extracted. The common-mode (CM) noise model with parasitic capacitive couplings is developed and the techniques to reduce the CM noise due to parasitic capacitive couplings are explored. Simulation and experiments were conducted to verify the analysis and the proposed techniques.

Analysis and Optimal Design of High-Frequency and High-Efficiency Asymmetrical Half-Bridge Flyback Converters

Abstract: The asymmetrical half-bridge (AHB) flyback converter is capable to achieve zero voltage switching and has lower voltage stress compared to the active clamp flyback converter. This topology gives much margin for components selection and transformer turns ratio design. It is well adapted to voltage step-down applications. However, the optimal design for AHB flyback converter taking current dip effect causing by components parasitic capacitances, and each component effect to power loss into consideration has never been explored. This article gives detailed operation and mathematical analyses of this effect. The optimal design procedure with the consideration of each circuit parameter is presented in this article. The transformer benefits low power loss from interleaving winding layout. A 56 W/inch3 1 MHz 65 W prototype with 100–250 V input is built to verify the feasibility of the converter. Experimental results show the peak efficiency 96.5% is achieved with 127 V input and the whole system efficiency under the entire input voltage range is above 93%.

A Soft-Switched Power Module With Integrated Battery Interface for Photovoltaic-Battery Power Architecture

Abstract: In conventional photovoltaic (PV)-battery systems, a centralized battery storage system (BSS) is typically connected through a separate bidirectional converter at the common dc link to support the PV system. It is known that a bidirectional converter typically requires more switches than a unidirectional converter, and hence, a complete PV-battery power interface will result in a high-cost system and will suffer high power losses. This paper proposed an integrated battery storage interface with soft-switching capability for module-integrated PV systems. In the proposed system, a multi-input converter (MIC) structure that consists of an integrated soft-switched quasi-resonant (QR) Cuk- and flyback-based circuit is presented. In this approach, the battery charging circuit is integrated with the input side of the PV power optimizer while the battery discharging circuit of the proposed system shares the output filter of the PV power optimizer, resulting in a compact and efficient system. The proposed converter is capable of tracking the maximum power point (MPP) and following the charging profile (constant voltage and constant current) of the battery. Moreover, all the switches in the proposed converter are able to achieve soft-switched turn on and turn off for different operating conditions. The operating principles and the theoretical analysis of the proposed system are presented. Experimental results on a 175-W proof-of-concept prototype are presented to demonstrate the features of the proposed converter.

A Constant Current Control Scheme for Primary-Side Controlled Flyback Controller Operating in DCM and CCM

Abstract: Primary-side regulation (PSR) flyback converters operating in discontinuous conduction mode (DCM) are widely used in low-power applications. In DCM, the peak current control method for PSR flyback is generally adopted to achieve constant current (CC) output. However, there are few effective schemes suitable for DCM and continuous conduction mode (CCM) operation of PSR flyback converters due to the difficulty in estimating the output information correctly, especially in the case of analog circuit control. In this article, a control scheme based on midpoint sampling method is proposed to achieve a high-precision CC control, which operates seamlessly as the operating mode switched between DCM and CCM. In order to verify the feasibility and performance of the proposed control, a control IC with the proposed CC control scheme has been implemented in 0.18 μ m 5 V/40 V BCD process. The experimental results show that the deviation of the output current is within ±1.93% under different input and load conditions.

The Optimal Design of A High-Temperature PCB-Embedded Transformer GaN-Based Gate-Drive Power Supply with A Wide-Input Range

Abstract: This paper presents the optimal design of a wide-input range, dual-output 10 W isolated active-clamp flyback (ACF) gate-drive power supply (GDPS) for high-temperature automotive applications Detailed analysis and comparison between Critical Conduction Mode (CRM) and Continuous Conduction Mode (CCM) are provided to select the operating mode A printed-circuit-board-embedded (PCB-embedded) transformer is carefully designed and it significantly improves the power density of the power supply A 10 W, GaN-based converter prototype switching at 1MHz has been developed to demonstrate the attained power density (532 W/in3), peak efficiency (897%), input voltage range (85 V to 28 V), maximum operating ambient temperature (105 °C at 85 V and 115°C at 28 V), and transformer input-output capacitance (97 pF)

A Digital Control Scheme for PSR Flyback Converter in CCM and DCM

Abstract: Due to the simple structure and low cost, the primary-side-regulation (PSR) flyback converter is widely used in small power applications. As the output voltage is sampled from auxiliary winding in PSR flyback converter, some sampling error exists, especially when continuous conduction mode (CCM) is introduced for higher power. To improve the constant voltage accuracy, a novel digital controlled sampling strategy is proposed. This scheme uses a digital ramp sampling method to sample output voltage in both discontinuous conduction mode (DCM) and CCM, and proposes a voltage adjustment strategy to adjust sampling errors in CCM without weakening the stability in the load-switch process. Finally, the experimental results validate the presented scheme and show that the output voltage error is less than 0.6% in a 20-V, 5-A PSR flyback prototype.

Sampled-Data Modeling for PCM and ZVS Controlled Critical Conduction Mode (CrCM) Active Clamp Flyback (ACF) Converter at Variable Switching Frequency

Abstract: Critical conduction mode (CrCM) active clamp flyback (ACF) converter is regarded as a good candidate for low power adaptor applications. However, the most adopted control strategy of variable-frequency peak current mode (VF-PCM) and discrete zero voltage switch (ZVS) control makes it difficult to get the accurate small signal model. Therefore, by using sampled-data modeling method, this paper proposes an exact small signal model of CrCM ACF converter for the first time. In the modeling process, the influence of discrete-ZVS control is firstly considered. The conduction time of power switch is regarded as the control signal, which is different from constant-frequency converter. The total current close-loop transfer function is simplified by the linear combination of single VF-PCM and discrete-ZVS control model. After considering the sampling effect and the modulator gain from the derived sampled-data model respectively, the control-to-output transfer function of CrCM ACF converter is developed. The analytical results are analyzed by comparing with single VF-PCM and the widely used average model. Finally, to validate the accuracy of the proposed model, a 65W 20V output CrCM ACF converter is simulated and measured. The verification shown that the proposed sampled-data model is basically agreement with the simulation and experimental results.

A New Primary PWM Control Strategy for CCM Synchronous Rectification Flyback Converter

Abstract: A new primary PWM (pulsewidth modulation) control strategy for continuous conduction mode (CCM) synchronous rectification (SR) flyback converter is proposed in this letter. The PWM signal for the primary switch has been divided into two pulses in a switching period (dual-pulse PWM, DP-PWM). The first pulse is a fixed narrow pulse, which is used to turn off the SR, whereas the second pulse is a regulated pulse for output voltage regulation. With the proposed DP-PWM control scheme, the shoot-through currents exist on both the primary side and secondary side of the CCM SR flyback converter can be effectively reduced. Meanwhile, the efficiency has been improved obviously. Detailed theoretical analysis has been presented and verified by a 12 V/2.5 A CCM flyback experimental prototype.

A New CCM/DCM Hybrid-Mode Synchronous Rectification Flyback Converter

Abstract: A new continuous conduction mode (CCM)/discontinuous conduction mode (DCM) hybrid-mode synchronous rectification (SR) flyback converter is proposed in this paper. This converter is realized by adding a combined switch in parallel with the auxiliary winding of the flyback transformer. The added switch is controlled to conduct a short period before the primary switch turns on , which shorts the windings of the transformer. The drain-source voltage of SR arises rapidly to reach the turn- off threshold voltage inside SR controller and the SR is turned off before the primary switch conducts. In this way, the overlapped period existed in a conventional CCM SR flyback converter is eliminated. Meanwhile, the normal operation of SR flyback in DCM is not affected. Detailed theoretical analysis has been presented and verified by a $12\,\text{V}/ 2.5\,\text{A}$ CCM/DCM hybrid-mode flyback experimental prototype. The results prove that the efficiency of the proposed SR method in CCM can be improved compared with the conventional one.

The Novel Quasi-Resonant Flyback Converter With Autoregulated Structure for Parallel/Serial Input

Abstract: In this paper, a novel quasi-resonant flyback converter that mainly comprises two modules of flyback converters is proposed. A relay is connected in series to the input terminals of two transformers, and the transformer input structure is adjusted according to the input voltage to improve the conversion efficiency. In addition, a novel frequency-limiting quasi-resonant control strategy for solving the limitations of the conventional quasi-resonant control strategies is proposed, wherein the switching frequency is increased under light load conditions. Here, the current-mode pulsewidth modulation IC is used as the core controller. The operating principle and design parameters of the converter are analyzed and discussed in detail. The experimental results prove the feasibility of the proposed circuit.

An Adaptive Sensorless Control Technique for a Flyback-Type Solar Tile Microinverter

Abstract: This article presents a novel sensorless control system for a solar tile microinverter employing the flyback topology. The elimination of current sensors from the circuit lowers the overall cost and reduces measurement noise introduced into the control system. The proposed control system eliminates both the high frequency inductor current measurement as well as the photovoltaic (PV) module current measurement. Additionally, an inductance observer is combined with the proposed technique to increase the accuracy of the high frequency inductor current estimation. A stability analysis proves the system to be stable. The proposed control system is experimentally validated on a microinverter prototype. Simulation and experimental results affirm the feasibility and performance of the control system. The experimental setup includes a grid simulator and a PV module simulator to test the system at varying irradiance levels. The proposed control system is also compared to methods presented in previous literature to demonstrate its superior characteristics.

A Constant Current Digital Control Method for Primary-Side Regulation Active-Clamp Flyback Converter

Abstract: Active-clamp flyback converter is now widely used because higher efficiency is obtained with soft-switching technique. However, opto-coupler is always applied in the feedback loop to acquire the output signal. To avoid the non-linearity and temperature drift of the opto-coupler, a constant current digital control method with peak current control is proposed for primary-side regulation active-clamp (PSRAC) flyback in this paper. Considering the charge balance principle, the output current can be calculated and controlled with primary-side control and only one low speed digital to analogy converter (DAC), two comparators and a digital unit are required in discontinuous conduction modulation (DCM) mode. Based on the proposed method, constant output current is realized. The proposed control scheme was verified by a FPGA controlled 2.00-10.00V/2.00A ac-dc PSRAC flyback converter.

Modeling and simulation of an integrated octagonal planar transformer for RF systems

Abstract: The work presented in this paper concerns the modeling of an integrated transformer in monolithic technology for high frequencies containing coils of planar type and magnetic circuit made of several layers of materials. Circular, square, and polygonal shapes of the planar coils are the important difference regarding transformer topologies. In this work, we have chosen the stacked octagonal form of coils. The transformer will be integrated into a converter of type flyback. We have opted for the Wheeler method and the S-parameters for determining the geometrical and the electrical parameters. The electrical π model presented summarizes perfectly the various parasitic effects generated by stacked layers of different materials constituting the transformer. The electromagnetic simulation, by using COMSOL Multiphysics 4.3 software, illustrates the current density and the distribution of magnetic field lines. We have also used software PSIM 6.0, to validate the equivalent electrical circuit of the transformer in flyback converter.

Stability Analysis of Constant Current Controlled Primary-Side Regulation Flyback Converter

Abstract: In low power applications, primary-side regulation (PSR) flyback converter with discontinuous conduction modulation (DCM) mode is widely used to realize constant output current for its simple structure and low cost. In peak current control method, the output current can be predicted from the primary peak current, the demagnetization time and the switching period. Based on the current prediction, a pulse width modulation (PWM) mode and a pulse frequency modulation (PFM) mode are used. However, as the output current cannot be sampled directly in PSR flyback converter, traditional small-signal modelling method based on the control and output variables cannot be used. And there is no stability analysis for these constant current (CC) controlled PSR flyback converters. In this paper, a discrete matrix analysis method is proposed to analyze the stability of CC controlled PSR flyback converter. An iterative matrix of the control and output variable perturbations is obtained and the stability can be acquired from the eigenvalues. Oscillation occurs in above PWM mode and stable control is realized in PFM mode. An improved PWM mode is thus proposed and analyzed for stable control. The analysis is verified in a PSR flyback converter with 1.92A.

Flyback Converter for Solid-State Lighting Applications with Partial Energy Processing

Abstract: The main contribution of this paper is to show a new AC/DC converter based on the rearrangement of the flyback converter. The proposed circuit only manages part of the energy and the rest is delivered directly from the source to the load. Therefore, with the new topology, the efficiency is increased, and the stress of the components is reduced. The rearrangement consist of the secondary of the flyback is placed in parallel with the load, and this arrangement is connected in series with the primary side and the rectified voltage source. The re-arranged flyback is only a reductive topology and with no magnetic isolation. It was studied as a power supply for LEDs. A low frequency averaged analysis (LFAA) was used to determine the behavior of the proposed circuit and an equivalent circuit much easier to analyze was obtained. To validate the theoretical analysis, a design methodology was developed for the re-arranged flyback converter. The designed circuit was implemented in a 10 W prototype. Experimental results showed that the converter has a THDi = 21.7% and a PF = 0.9686.

Zvs control circuit for use in a flyback power converter

Abstract: A ZVS (zero voltage switching) control circuit for use in a flyback power converter includes a primary side controller and a secondary side controller. The primary side controller generates a switching signal to control a power transformer through a power transistor to generate an output voltage. The secondary side controller generates an SR (synchronous rectifier) signal to control an SR transistor at a secondary side of the power transformer. The SR signal includes an SR-control pulse and a ZVS pulse. The SR-control pulse controls the SR transistor according to a demagnetizing period of the power transformer. The ZVS pulse determines the starting timing of the switching signal to achieve zero voltage switching for the power transistor. The secondary side controller generates the ZVS pulse after a delay time from when the power transformer is demagnetized. The delay time is determined according to an output load of the output voltage.

High-Efficiency Three-Phase Single-Stage Isolated Flyback-Based PFC Converter With a Novel Clamping Circuit

Abstract: This article analyzes a three-phase single-stage isolated flyback-based power factor correction converter and presents a novel clamping circuit to capture the transformers leakage inductance energy. The converter unity power factor operation is obtained by using the inherent resistance property of discontinuous conduction mode. Thus, the input current shaping circuit is eliminated and resulted in a single-loop control system. Therefore, the converter control circuit requires only one sensor, which decreases the system cost, and also increases the system robustness to high-frequency noise. With the proposed clamping circuit, the transformers leakage inductance energy is successfully captured in clamping capacitor, and thereby, it is fed to the dc load by using an auxiliary two-switch forward converter which enhanced the overall operating efficiency of a converter. The converter detailed steady-state operation and the design considerations are presented. Each power component voltage stress expressions are derived to simplify the converter design, and the converter small-signal model is presented to help the controller design. The novelty and performance of the converter is verified by both simulation and experimentation.

Switching power supply device

Abstract: The invention discloses a switching power supply device. The switching power supply device comprises an asymmetric half-bridge flyback converter and a controller; and the asymmetric half-bridge flyback converter is used for converting an input voltage into an output voltage, and comprises a main switch, an auxiliary switch, a transformer and a one-way clamping network used for controlling a negative peak value of an excitation inductive current. A controller is used for controlling the main switch, the auxiliary switch and the one-way clamping network, so that the switching power supply deviceworks in a certain working state. The switching power supply device is characterized in that when the output load current is greater than or equal to a first load current set value, the controller enables the switching power supply device to work in an asymmetric half-bridge flyback mode; and when the output load current is smaller than the first load current set value, the controller enables theswitching power supply device to work in a clamping asymmetric half-bridge flyback mode. Under the condition that the advantages of full load and heavy load high efficiency of the switching power supply device are kept, the current effective value of the power device under light load and no load can be reduced, the light load efficiency is greatly improved, and the no-load loss is reduced.

Average Inductor Current Measure and Control Strategy for Multimode Primary-Side Flyback Converters

Abstract: Primary-side flyback converter (PSR) is widely used among small and medium power applications for its simplicity and cost effectiveness. However, it is hard to measure the current of secondary side due to the special structure characteristic of PSR. Conventionally, a peak current measurement strategy is adopted to measure the current of primary inductor. However, the sampling method is just for one conduction mode and is affected by the propagation delay between the control signal and actual turn- off instant of mosfet . Thus, a compensation circuit is needed to improve the accuracy, which leads to a large area and cost of the controller. In this work, a kind of average inductor current measure and control strategy for multimode is introduced. The average inductor current measurement strategy is based on the Miller stage to recognize the state of the mosfet, which eliminates the error caused by the mosfet . The average current of primary inductor is obtained and there is no need to estimate the rising slope and the peak value of the inductor current. To verify the feasibility of the proposed method, a controller for charging application is fabricated integrated with the proposed method. Hardware experimental results show that the control system can properly operate in multimode. The accuracy of constant output current is ±1% and the line regulation of the system is 1.6% under the input line voltage ranges from 85 to 265 Vac.

An Energy-Based Analysis for High Voltage Low Power Flyback Converter Feeding Capacitive Load

Abstract: Generally, battery-fed capacitive loads are charged to high voltages in series of switching cycles with smaller fragments of energy delivered to the load in every cycle to ensure an efficient charging process. In high voltage low power (HVLP) flyback charging circuit, significant portion of input energy drawn from the source in a cycle is utilized by the effective parasitic capacitance of the HV transformer and semiconductor devices and circulated back to the source at the end of the cycle. This reduces the energy delivered to the load per cycle and hence the net energy delivered in the charging process. In this paper, an energy-based analysis and simplified energy-based model for HVLP charging circuits is derived. An energy-based approach is appropriate to describe and define the HVLP converter behavior in terms of load energy component and circulating energy component. The derived energy-based model is extended to obtain analytical closed-form expressions governing the essential parameters of the charging circuit. The proposed energy-based model and analytical formulation of essential parameters are experimentally validated on a 0–2.5 kV programmable high voltage charging circuit prototype fed from 12 V input battery source.

State Space Modeling and Stability Analysis of the Flyback Converter

Abstract: In this paper, state space and stability analysis are revalued to restructure with the published articles for the practical applications before implementation of the Flyback power converters. The design guidelines and optimizations are espoused in such a manner to heighten high power conversion ratio, transient response, tight regulations, compact dimension, robust reliability and high power density in the converter for the transportable applications

Full-Bridge Active-Clamp Forward-Flyback Converter with an Integrated Transformer for High-Performance and Low Cost Low-Voltage DC Converter of Vehicle Applications

Abstract: This paper presents a full-bridge active-clamp forward-flyback (FBACFF) converter with an integrated transformer sharing a single primary winding. Compared to the conventional active-clamp-forward (ACF) converter, the proposed converter has low voltage stress on the primary switches due to its full-bridge active-clamp structure, which can leverage high performance Silicon- metal–oxide–semiconductor field-effect transistor (Si-MOSFET) of low voltage rating and low channel resistance. Integrating forward and flyback operations allows the proposed converter to have much lower primary root mean square (RMS) current than the conventional phase-shifted-full-bridge (PSFB) converter, while covering wide input/output voltage range with duty ratio over 0.5. The proposed integrated transformer reduces the transformer conduction loss and simplify the secondary structure of the proposed converter. As a result, the proposed converter has several advantages: (1) high heavy load efficiency, (2) wide input voltage range operation, (3) high power density with the integrated transformer, and (4) low cost. The proposed converter is a very promising candidate for applications with wide input voltage range and high power, such as the low-voltage DC (LDC) converter for eco-friendly vehicles.

Digitally controlled GaN-based MHz active clamp flyback converter with dynamic dead time optimisation for AC–DC adapter

Abstract: The active clamp flyback (ACF) converter utilising gallium nitride (GaN) devices with high-switching frequency and high efficiency is impressive in system miniaturisation for AC–DC adapters. Owing to poor reverse conduction of GaN devices, the improper dead time between two switches can cause large power consumption in high frequency. This study proposes a dynamic dead time optimisation technique for GaNs ideal zero-voltage switching (ZVS) to address the issue. It adjusts the clamp switch on time to avoid large reverse conduction voltage stress on the main switch in different loads conditions. In addition, a new control scheme for clamp switch is introduced for enhancing efficiency in light to medium load. These techniques are experimentally verified on a 45 W (20 V/2.25 A) prototype of an ACF converter with a field-programmable gate array. The controller enables the system to operate at 1 MHz and dynamically modulates the dead-time under universal input and full load. With the light load ZVS control scheme, the system can achieve a maximum efficiency of 94.12 and 80.23% in the worst case. The prototyped converter can achieve power density (exclude case and controller) of 18 W/in 3 .

Multitransformer Primary-Side Regulated Flyback Converter for Supplying Isolated IGBT and MOSFET Drivers

Abstract: This paper presents primary-side voltage regulated multitransformer quasi-resonant flyback converter (MTFC) for supplying isolated power switch drivers. The proposed topology offers distinct advantages over frequently used flyback converter possessing one high frequency transformer with isolated multiple outputs. Particularly, when a large number of separate dc supply units is required, then MTFC enables improved regular distribution of magnetic coupling between the common primary and the multiple secondary transformers’ windings providing a high degree of galvanic and electromagnetic isolation between multiple outputs. Primary side voltage regulation is based on the average output voltage estimation using auxiliary RDC circuit mounted across the primary windings. Operation principles of MTFC are enhanced with analytical study of cross regulation of multiple output voltages at unbalanced load conditions, indicating reduced voltage deviation of multiple outputs by applying the primary-side average voltage regulation. Experimental results of prototype 2-, 3-, and 6-transformer quasi-resonant flyback converters confirmed their cross regulation quality and application potential for independent multiple output supplies.

Control and monitoring of a Flyback DC-DC converter for photovoltaic applications using embedded IoT system

Abstract: In this article, the authors present an Internet of Things (IoT) solution for controlling and monitoring a low power photovoltaic system (250 W). Power conditioning is performed by a DC-DC Flyback converter with active clamping. An ESP32 microcontroller is used to implement an output voltage control loop and to communicate, online and in real time, with an internet server. The effectiveness of voltage regulation is proven with experimental results and the authors present evidence that the IoT features work properly.

Analysis of the Input Current Distortion and Guidelines for Designing High Power Factor Quasi-Resonant Flyback LED Drivers

Abstract: Nowadays, LED lamps have become a widespread solution in different lighting systems due to their high brightness, efficiency, long lifespan, high reliability and environmental friendliness. The choice of a proper LED driver circuit plays an important role, especially in terms of power quality. In fact, the driver controls its own input current in addition to the LED output current, thus it must guarantee a high power factor. Among the various LED drivers available on the market, the quasi-resonant (QR) flyback topology shows interesting benefits. This paper aims at investigating and analyzing the different issues related to the input current distortion in a QR flyback LED driver. Several effects, such as the distortion caused by the ringing current, crossover distortion due to transformer leakage inductance and crossover distortion due to the input storage capacitor have been experimentally reported. These effects, not previously studied for a high power factor (Hi-PF) QR flyback, have been analyzed in depth. Finally, some practical design guidelines for a Hi-PF QR flyback driver for LED applications are provided.