Synchronous Rectification Scheme Research Articles

High-Performance Light Emitting Diode Lighting Circuits and Their Interior Design Applications

This study explores the application of the half-bridge Inductor-Inductor-Capacitor (LLC) resonant converter in Light Emitting Diode (LED) lighting driver power supplies, with a specific focus on improving efficiency and dimming capabilities. The investigation begins with an analysis of the sliding mode control (SMC) method, utilizing a constant-current design with a fixed switching frequency (FWF). A novel fuzzy frequency-selective SMC dimming strategy is proposed to recognize the challenge of significant output voltage ripple during dimming under a FSF. To address the ripple issue during dimming, an electromagnetic filtering circuit is designed, and a zero-voltage turn-on Metal—Oxide—Semiconductor (MOS) tube is introduced, incorporating a synchronous rectification scheme to mitigate losses in the secondary-side rectification diode. The study comprehensively considers a current-mode self-driven method, specifically tailored to the LLC circuit’s different operating modes. The LLC resonant circuit, along with the subsequent synchronous rectification circuit, is meticulously designed for a 252 W LED driver power supply prototype. A closed-loop simulation circuit model is developed using PSIM software in experimental validation. The feasibility of SMC based on a FSF is affirmed through a comparative analysis of SMC signal waveforms, steady-state output current (OC) models, and resonant tank current waveforms. The investigation into the OC under various SMC conditions demonstrates the half-bridge LLC resonant converter’s ability to achieve stable output with minimal ripple. The designed LED lighting circuit is applied to indoor design, providing adjustable LED brightness and switch status at different power levels. Although obstacles slightly impact the communication quality of the circuit, it remains suitable for the majority of users’ needs.

Geometrical State-Plane-based Synchronous Rectification Scheme for LLC Converter in EVs

Geometrical State-Plane-based Synchronous Rectification Scheme for <i>LLC</i> Converter in EVs

Fundamental impedance-based digital synchronous rectification scheme for bidirectional CLLC resonant converters

Fundamental impedance-based digital synchronous rectification scheme for bidirectional CLLC resonant converters

A Novel Synchronous Rectification Scheme With Low Computational Burden for LLC Resonant Converter in EV Charger Applications

In EV charger applications, high voltage level and high computational burden caused by multiple charging modes bring serious challenges to the synchronous rectification (SR) of LLC resonant converter. Conventional SR schemes can be classified as current sensing-based, voltage sensing-based and sensorless, which are limited by high cost of current sensing, difficulty of high voltage sensing, narrow operating range or high computational burden, respectively. To deal with these problems, this paper proposes a novel SR scheme for LLC resonant converter in EV charger applications. In this scheme, SR control signals are tuned only by main control signal, output voltage and output current, which are naturally available from main controller in EV charger. To this end, no additional signal sensing is required and the cost for SR is reduced. Moreover, the SR tuning principle is on the basis of Kirchhoff's law and phase relationship between main control signal and secondary-side current, which no longer needs to calculate complicated models. Meanwhile, the foresaid tuning process of SR control signals can be implemented by analog circuits. With these effects, this scheme can tune SR control signals effectively over a wide operating range with low computational burden. Furthermore, a virtual current injection strategy is designed to suppress the inversion current of synchronous rectifier. It can guarantee no inversion current and low body diode conduction (BDC) loss. A 600-V input 200 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 300-V output LLC prototype converter is built to verify the proposed SR scheme.

Universal Synchronous Rectification Scheme for LLC Resonant Converter Using Primary-Side Inductor Voltage

In recent years, many advanced modulation strategies have been applied in LLC resonant converters, resulting in the increased demand for the synchronous rectification (SR) schemes without modulation strategy limitation. However, the conventional universal SR schemes are mainly on the basis of primary/secondary side current or drain-source voltage of synchronous rectifiers, which are limited by high cost of current transformer (CT) and loss of duty cycle caused by parasitic inductance, respectively. To deal with these problems, this paper proposes a novel SR scheme for LLC resonant converter. Firstly, a SR analysis method on the basis of the idea of power transmission is proposed. It can decouple SR from modulation strategy. Based on this method, this paper proposes a universal SR scheme using primary-side inductor voltage. The scheme is no longer restricted by the modulation strategy of converter. Meanwhile, no CT is required, thereby reducing the cost and conduction loss. Thanks to the large signal sensing-based, this scheme has good noise immunity. Moreover, it eliminates the negative effect of parasitic inductance by integral operation. With these effects, it has high accuracy of SR. Furthermore, an easily-debugged analog implementation is designed, which only needs to adjust one component parameter. Finally, experimental results show that the proposed scheme is compatible with different modulation strategies, and it has higher efficiency than the commercial SR scheme in a wide range of operating conditions.

Synchronous Rectification Based on Resonant Inductor Voltage for CLLC Bidirectional Converter

Synchronous rectification (SR) is an effective method to reduce the secondary side conduction loss of CLLC bidirectional resonant converter and improve its efficiency, but the SR driving signal in CLLC converter is hard to determine. Existing SR signal generating methods can be divided into three categories: theoretical calculation, voltage detection, and current detection. Compared with the other two methods, the current detection method has wider applicability and is insensitive to parasitic parameters, but usually requires lossy, bulky and costly current sensors, increasing the cost and size of the converter. This article proposed a SR scheme based on resonant inductor voltage. The polarity of the resonant current is obtained indirectly through the inductor voltage, thereby avoiding the use of current sensors. To handle the false pulses problem caused by parasitic oscillation, a corresponding SR control strategy is proposed. The SR driving signal is then adjusted according to the delay and transient requirements. Experimental results on a 380V/270V 3kW CLLC converter prototype were presented to verify the effectiveness of the proposed SR method.

An Optimized Digital Synchronous Rectification Scheme Based on Time-Domain Model of Resonant CLLC Circuit

Uncontrolled rectification on the secondary side of the resonant CLLC circuit causes a large amount of conduction loss. Accurate synchronous rectification (SR) can reduce conduction loss by replacing rectifier diodes with mosfets’ channels exactly. The accuracy of the SR signals depends on the determination of the zero-crossing points of the secondary side resonant current. In this article, an accurate time-domain model is introduced for the resonant CLLC circuit to obtain these zero-crossing points. This modeling method is more accurate than first harmonic approximation and requires less computational effort than extended harmonics approximation. Compared with previous time-domain modeling methods, the proposed time-domain model gives detailed circuit state expressions and covers the entire circuit operating states. Relying on the accurate circuit model, the SR scheme proposed in this article can adaptively generate SR signals in different frequency ranges and has the ability to switch modes smoothly. And this method can be used for the later efficiency optimization of CLLC converters that do not originally have SR function, only through the control program update. Moreover, the robustness of the proposed SR method is analyzed, and the proposed concept is verified through a 3-kW resonant CLLC prototype.

Bi-Directional High-Conversion-Ratio CLLC Resonant Converter with a New Synchronous Rectification Scheme for Low Conduction Loss

Bi-Directional High-Conversion-Ratio CLLC Resonant Converter with a New Synchronous Rectification Scheme for Low Conduction Loss

Efficiency loss breakdown for synchronous rectification scheme for automotive applications

This paper presents a synchronous rectification scheme using a six-phase Lundell alternator and a bespoke MOSFET based active rectifier. The control of the alternatorrectifier system is divided into the hysteresis dc-link voltage control and the switching pattern algorithm. The first allows to keep the dc-link voltage at the required 14 V level, while the latter reproduces the same switching pattern as that of a passive rectifier. The system is tested at three different speeds and the results are compared against the body diodes of the MOSFETs in the active rectifier. The harmonic analysis of the generated waveforms indicates the capability of the control algorithm to generate the same switching pattern of a passive rectifier. Finally, the efficiency measurements illustrate a significant efficiency improvementusingasynchronousrectificationschemeandMOSFETs with low on-resistance.

Self-Driven Synchronous Rectification Scheme Without Undesired Gate-Voltage Discharge for DC-DC Converters With Symmetrically Driven Transformers

This paper proposes a new self-driven synchronous rectification scheme for dc-dc converters with symmetrically driven transformers and wide input voltage range. The driving signals are obtained from the output inductor. Two auxiliary switches are utilized to turn off the main switches properly. Two extra auxiliary switches, which are controlled by a delayed signal from the inductor, are added to avoid the undesired gate discharge. This approach can achieve high efficiency and is suitable for practical applications. Experimental results based on a 36-75 V input, 2.5 V/30 A output prototype are shown to verify the proposed scheme.

Low output voltage AC/DC converter with a new scheme of synchronous rectification that complies with IEC 1000-3-2 regulations

The aim of this paper is to study the performance of an AC/DC converter with low output voltage and low input current harmonic content. In order to obtain low output voltages with a high efficiency, synchronous rectification is mandatory. When the output voltage is low, it is very difficult to use self-driven synchronous rectification and additional windings are used to properly drive the metal oxide semiconductor field effect transmitters (MOSFETs). Besides this, IEC 1000-3-2 regulations impose low input current harmonic contents for power levels higher than 75 W. In this paper, a recently proposed synchronous rectification scheme is combined with a modified input current shaper to design a 100 W, 3.3 V AC/DC converter that complies with IEC 1000-3-2 regulations. The efficiency obtained in the prototype was very high for this application (86%) and both the size increase and the cost increase were quite low in comparison with the original topology with no synchronous rectification and no IEC 1000-3-2 compliance.