Half-bridge LLC Resonant Converter Research Articles

Review Of Control Methods of Dual-Output Half-Bridge LLC Resonant Converter

Dual-output half-bridge LLC resonant converters are widely used in data centres, aerospace, portable electronic devices, new energy vehicles and other fields due to their superior performance of high frequency, high efficiency and high power density. This paper analyses the topology and operating principle of the dual output LLC resonant converter; introduces the traditional control methods and the new control methods in recent years. For each control method, its principle, characteristics, advantages and disadvantages are described. Finally, the future research direction and development trend of dual-output half-bridge LLC resonant converter are outlooked.

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.

Passivity-based control strategy for resonant converter based on Euler–Lagrange model

The LLC resonant converter is a widely used DC/DC converter that offers the benefit of enabling soft switching compared to classical DC/DC converters. However, traditional PI control strategy based on a linear model has drawbacks such as slow dynamic response and poor anti-interference performance. To overcome the shortage, a passivitybased control strategy based on the Euler–Lagrange (EL) model is proposed in this paper to improve the dynamic performance of the half-bridge LLC resonant converter. In addition, the stability of the system based on the proposed strategy is analyzed and verified. Further, the effectiveness and performance of the proposed strategy is verified in the simulation by comparing with the traditional PI controller. Finally, a prototype was built to verify the dynamic performance of the LLC resonant converter based on the proposed control strategy.

A Novel Integrated Electronic Lighting Driver Circuit for Supplying an LED Projection Lamp with High Power Factor and Soft Switching Characteristics

The traditional light source of projection lamps adopts a halogen lamp, which has the advantages of high brightness, but its luminous efficiency is not good and consumes energy. A light-emitting diode (LED) has the characteristics of high luminous efficiency and energy savings and can be used as a new light source for projection lamps. The conventional two-stage electronic lighting driver circuit for supplying an LED projection lamp is composed of an AC-DC converter with power factor correction (PFC) as the first stage and a DC-DC converter for providing rated lamp voltage and current as the second stage. The conventional LED projection lamp driver circuit has more circuit components, a higher cost and limited efficiency. Therefore, this paper proposes a novel electronic lighting driver circuit for supplying an LED projection lamp with PFC function, which integrates a modified stacked dual boost converter and a half-bridge LLC resonant converter into a single-stage power-conversion circuit. The inductor inside the modified stacked boost converter is designed to operate at discontinuous conduction mode (DCM) for the driver circuit achieving PFC. Wide bandgap semiconductor devices silicon carbide (SiC)-based Schottky diodes are utilized to reduce power diode losses, and soft switching is implemented in the proposed LED projector lamp driver circuit to reduce the switching losses of the power switches and thus improve circuit efficiency. This paper has completed a single-stage prototype driver circuit for an LED projection lamp with PFC function, and the prototype circuit has a high power factor (PF > 0.98), low input current total-harmonic-distortion (THD < 6%) and high efficiency (>89%) in the case of an AC input power supply with an RMS value of 110 volts, and both power switches have the characteristics of soft switching.

Novel Half-Bridge LLC Resonant Converter With Variable Resonant Inductor

Novel Half-Bridge LLC Resonant Converter With Variable Resonant Inductor

A high-efficiency primary-side regulation control strategy for half-bridge LLC resonant converter with wide input voltage range

The requirement of the half-bridge LLC resonant converter with a wide input voltage range is becoming higher in photovoltaic applications because of its simple structure and low switching loss. Conventional frequency modulation (FM) requires a wide switching frequency range and a high-quality factor circuit design, leading to reduced efficiency and large component volumes at light loads. To solve the problems, a high-efficiency control strategy using adaptive pulse-width and frequency modulation (APWFM) is proposed. APWFM adjusts the gain by changing the switching frequency and duty cycle simultaneously. When the output power is below the reference value, the switching frequency decreases linearly as the output power decreases, and the duty cycle is simultaneously modulated to achieve constant output voltage, so the switching frequency variation range is smaller than FM. This results in improved light or medium load efficiency in a limited frequency range while keeping a small volume of magnetic components. Also, the proposed control strategy is realized with primary-side regulation (PSR) to eliminate the optocoupler and simplify the control circuit. Experimental results demonstrate a significant improvement in efficiency at medium and light loads compared to FM, and the average efficiency is improved by 5% based on low cost and simple operation.

Resonance Characteristics of the LLC Resonant Half-Bridge Converter for the Rapid Charging of Personal Mobility Device Smart Batteries

This study discusses the resonance characteristics of the LLC resonant half-bridge converter and smart battery charging for the fast charging of personal mobility devices (e.g., electric kickboards, segways, hoverboards, electric bicycles, and electric motorcycles), whose use is rapidly increasing. Through the analysis of resonance characteristics, this study aims to validate that fS > f0 is the most appropriate correlation in the relationship between resonant frequency (f0) and switching frequency (fS) that is suitable for the rapid charging of batteries of personal mobility devices. Additionally, the proposed half-bridge converter does not charge the battery from discharge or misconnection based on the detection of the battery voltage for the batteries of personal mobility devices. Therefore, the proposed converter suggests a charging system based on battery state detection that stably performs rapid charging of the batteries of personal mobility devices by equalizing the battery voltage and the charger voltage through a pre-charge operation.

Design and Comparative Analysis of an Ultra-Highly Efficient, Compact Half-Bridge LLC Resonant GaN Converter for Low-Power Applications

For low-power applications, this paper presents the development and design of a compact and ultra-highly efficient half-bridge LLC resonant converter. By using Galium Nitride (GaN) devices and high-efficient magnetics, the efficiency and power density of resonant converters can be improved. Compared to Silicon MOSFETs, GaN high-electron-mobility transistors (GaN HEMT) have a lower output capacitance and gate charge, resulting in lower driving loss and shorter dead times. Consequently, the proposed LLC converter based on GaN devices has excellent performance characteristics such as ultra-high efficiency, low switching losses, compact size, high voltage endurance, high operating temperature and high operating frequency. Furthermore, the proposed resonant converter features soft switching properties that ensure that the switches and diodes on the primary side are always switched at zero voltage and current. By doing so, LLC resonant converter switching losses are significantly reduced by up to 3.1%, and an overall efficiency of 98.5% is achieved. The LLC resonant converter design with GaN HEMT has great advantages over Si MOSFET solution regarding efficiency, overall losses, switching loose and power factor correction. A 240 W, 240 V to 60 V half-bridge GaN HEMT LLC resonant converter is simulated with a switching frequency of 75 KHz, along with the comparative analysis of the Si metal oxide semiconductor field effect transistor (MOSFET) solution. Moreover, the design and analysis of highly efficient magnetics with a power factor of 0.99 at full load is presented. A 240-Watt single stage LED driver with power factor correction is also designed to verify and compare the performance of proposed LLC resonant converter.

Research on the development and intelligent application of power environmental protection platform based on big data

Abstract In order to improve the practical effect of the power environmental protection platform, this paper combines the big data technology to develop and design the power environmental protection platform. In this paper, a power factor correction (PFC) and resonant half-bridge joint controller is used to combine the traditional two-level topology into one-level topology. Moreover, this paper adopts a fixed frequency half-bridge LLC resonant converter with a simple control circuit to obtain a stable resonant half-bridge controller with a fixed output voltage. The choice of this overall power topology architecture can not only meet the design requirements, save costs and simplify the control of the circuit, but also improve the efficiency of the whole machine and the performance of the power environmental protection platform. The experimental research shows that the power environmental protection platform based on big data proposed in this paper can effectively improve the effectiveness of power environmental protection strategies.

An Electrolytic-Capacitor-Less PFC LED Driver With Low DC-Bus Voltage Stress for High Power Streetlighting Applications

This paper presents a single-stage, soft-switching, high power factor, flicker-free LED driver without any electrolytic capacitors for streetlighting application. The proposed LED driver consists of a buck-boost type power factor correction (PFC) circuit integrated with an asymmetric half-bridge LLC resonant converter. The buck-boost type PFC circuit provides a high power factor, low input current harmonics, and low dc bus average voltage. Unlike other methods that use the first harmonic approximation (FHA) analysis or the differential equations in time domain to analysis the LLC circuit, in this paper, a Fourier series-based analysis is proposed. The proposed method provides better accuracy in comparison with the FHA while being simpler than the time domain analyze method. The half-bridge LLC resonant converter is designed such that ZVS is obtained for the entire input voltage range (185 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 265 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$V_{rms}$</tex-math></inline-formula> ), and for 20% to 100% of the full-load power. In addition, a magnetic integration technique is utilized to increase efficiency and reduce converter size. The designed control system enables lowering the output current ripples without using any electrolytic capacitors. To verify the feasibility of the proposed LED driver, a 200 W prototype is implemented. The proposed LED driver achieves maximum efficiency of 94.6%, high PF, and a maximum of 15% output current ripples.

Long Life Power Factor Corrected LED Driver with Capacitive Energy Mechanism for Street Light Applications

Conventional switch-mode LED drivers have problems such as poor performance in harmonic distortion, flickering, power factor correction, stresses on the switches, high switching losses, large size, and high cost. To resolve these problems, we propose a long-life LED driver with the ability of power factor correction. The proposed system is based on the integration of a half-bridge LLC resonant converter and two boundary-conducted boost converters. Both boost converters share a common inductor designed in such a way that both boost converters work in boundary conduction mode to attain the natural power factor correction. Half-bridge LLC resonant converter has soft switching characteristics, which assure the zero-voltage switching (ZVS) of primary-side switches and zero-current switching (ZCS) of diodes on the secondary side. This significantly reduces switching losses and improves the overall efficiency of the system. Voltage divider capacitors are used on the input side, which minimizes the bus voltages. The proposed system has two identical secondary windings with a coupled inductor to eliminate the mismatch between them, which powers two independent LED strings. The simulation of a 100-watt 240 V AC converter yields the approximate sinusoidal shape of the input current. It shows that the switches on the primary side are operated in ZVS and the diodes in ZCS. At 240-volt AC input, the efficiency is 87.4%, the total harmonics distortion (THD) is 10.98%, and the power factor (PF) is 0.98.

Efficiency Considerations of LLC Resonant Converter for Induction Heating Application

Due to the high efficiency, high power density and low EMI provided by the LLc resonant converter, it has been widely used by researchers in many fields such as induction heating (IH). This converter is based on a resonant circuit consisting of a capacitor (Cr) and two inductors Lr, Lm operating in wide output load regulating ranges for the purpose of achieving good efficiency for very high power systems using a high operating frequency. This paper aims to present a half-bridge LLC resonant converter based on power supplies for IH applications. The analysis contains five components: half bridge inverter, resonant tank, high frequency transformer, rectifier and coil. The switching bridge generates a square waveform to excite the LLC resonant tank, which will produce a resonant sinusoidal current which is transferred to the secondary of the converter through a high-frequency transformer. as it scales the voltage up or down according to the output requirements. The load represented by the equivalent circuit of the coil and work-piece is fed by the current transformed by the rectifiers. This paper provides an improved knowledge of the control of the output power for high-temperature applications through numerical simulation Considering that the load parameters and resonant frequency vary substantially throughout the system operation. The results of testing demonstrated that the proposed scheme and assembly has good efficiency, and it is well suited for magnetic induction heating systems.

High-Power-Density DC–DC Converter Using a Fixed-Type Wireless Power Transmission Transformer with Ceramic Insulation Layer

In this study, we propose the use of a short-distance and fixed-type wireless power transmission transformer via a half-bridge LLC resonant converter. A ceramic insulating layer was used instead of an air gap, meaning that the heat generated from the transformer core and the PCB winding was quickly transferred to the external metal case, with the ceramic insulating layer acting as a heat pipe. In order to stabilize the output voltage, we proposed the use of IR photo tunnel technology, and it was applied to two ceramic insulating layers so that the voltage error signal of the secondary output voltage could be transmitted as light to the primary side. As a result, it was possible to physically separate the primary and secondary sides of the power circuit centering on the ceramic insulating layer. The experiment was carried out with the input voltage of 400 V, the output voltage of 54 V, the maximum output power of 1 kW, and the switching frequency of 1.3 MHz or higher. As a result, the maximum operating frequency was 1.83 MHz, and the output voltage stability to the load was 0.49% or lower. The power density of the experimental circuit was 380 W/in3 or higher, and the maximum power conversion efficiency was approximately 93% or higher.

Control Strategy of Half-Bridge Three-Level LLC Resonant Converters With Wide Output Voltage Range

A half-bridge three-level LLC (HBTL-LLC) resonant converter has low voltage stress, high power density, and a large range of soft switching, so it is widely considered and applied, but there are problems such as a small adjustable range of output voltage and difficulty in implementing soft switching. In this article, based on the detailed analysis of the working principle of an HBTL-LLC resonant converter, a three-stage hybrid control strategy is proposed: frequency modulation (FM) control is used when the gain is high, and phase shift control is used when the gain is low. If the phase shift angle achieves the critical value of the soft switch and the gain is still high, variable-frequency burst control is used to expand the adjustment range of the output voltage and improve the power efficiency at low voltage output. Finally, a 500-V, 15-A prototype was designed and analyzed and experimented. The results verified the feasibility and effectiveness of the proposed three-stage hybrid control strategy.

Steady-State Analysis and Optimal Design of an LLC Resonant Converter Considering Internal Loss Resistance

In this paper, a steady-state model of an LLC resonant half-bridge converter with internal loss resistance is proposed, in order to maximize power conversion efficiency, and steady-state characteristic equations of DC voltage gain and input impedance are derived for the optimal design of the converter. First, to confirm the validity of the steady-state characteristic equation and the optimal design process, a prototype converter with a maximum output of 2 kW was designed. Through comparison of simulation, calculation, and experimental results obtained from the prototype test, it is shown that the calculation results proposed in this paper were closer to the experimental results than the calculation results obtained under the lossless condition. In addition, the relationship between the switching frequency and the load current of the prototype was compared, in order to determine the operating range of the switching frequency, which is important in the converter design stage. In this case, it was confirmed that the calculated value reflecting the internal loss showed a close result. In conclusion, we confirm the usefulness of the analysis results reflecting the internal loss resistance proposed in this paper and the optimal design process.

A Hybrid Control Strategy for Half-bridge Three-level LLC Resonant Converter

The half-bridge three-level LLC resonant converter uses the resonant process of the inductance and the capacitance to transfer energy. It has the advantages of low voltage stress on the switch and high efficiency, but there are problems such as narrow voltage gain range. To widen the voltage gain range of the converter, a hybrid control strategy for a half-bridge three-level LLC resonant converter is proposed in this paper. The voltage gain of the converter is divided into three gain intervals: low, medium and high. Burst control is used in the low gain interval, phase shift control is adopted in the middle gain interval, and frequency modulation control is adopted in the high gain interval. The experiment results show that the proposed control strategy can realize a wide range of output voltage gain of the converter.

Voltage Multiplier with High Input/Output Voltage Gain from Center-Tap Rectifier-Voltage Tripler and Quadrupler

This paper proposes new rectifiers in the center-tap transformer to provide higher input/output (I/O) voltage gain with an equal transformer turns-ratio in the LLC resonant converter: a voltage tripler rectifier and a voltage quadrupler rectifier, which have simple structures with one capacitor and two diodes, and three and four times higher I/O voltage gain than a center-tap rectifier, respectively. Each rectifier is compared in terms of the transformer turns-ratio and the magnetizing offset current, and the voltage and current stresses in the capacitors and diodes. The validity of these proposed rectifiers in the half-bridge (HB) LLC resonant converter is confirmed by the experimental results from a 100 V/200 W output prototype.

Planar Magnetic Integration Design Based on LLC Resonant Converter

High power density and high efficiency is a major trend in the development of power converters. The main measure to reduce the size of power converter is to improve the working frequency, and the limiting factor is the size of magnetic components. With the development of new semiconductor devices, the working frequency of power converters has been significantly improved, which gives us the opportunity to apply printed circuit board (PCB) winding planar magnetics. Compared with the traditional high frequency magnetics, planar magnetics not only reduce the size of the magnetic components effectively but also improve reliability through repeatable automated manufacturing, which is convenient for large-scale production. Magnetic integration is another method to reduce the size of the power converter. In this paper, a new magnetic structure based on PCB winding is proposed, which integrates inductance and transformer into one component. And the inductor can be independent of the transformer. In this structure, the inductance of inductor and excitation inductance of transformer can be easily controlled by changing the number of winding turns or the length of the air gap. A 20-W 200-kHz half-bridge LLC resonant converter with a peak efficiency of 94.9% is built to verify the feasibility of the designed planar magnetic integrated structure.

A Single-Stage High Power Factor Power Supply for Providing an LED Street-Light Lamp Featuring Soft-Switching and Bluetooth Wireless Dimming Capability

Light-emitting diode (LED) has the characteristics of environmental protection and energy saving, having become the lighting source of a new generation of street-light lamps. The traditional two-stage power supply for providing an LED street-light lamp is composed of an AC-DC converter with a power-factor-correction (PFC) function at the front stage and a DC-DC converter at the rear stage. The two-stage power supply for an LED street-light lamp has a large number of electronic components and costs, and the circuit efficiency is not high. Therefore, this paper presents a novel single-stage high power factor AC-DC power supply for providing an LED street-light lamp featuring soft-switching and Bluetooth wireless dimming capability through using smart tablets or smartphones to remote control the output power of the LED street-light lamp for achieving energy-saving benefits. The proposed AC-DC LED power supply integrates an interleaved buck converter circuit with coupled inductors and a half-bridge LLC resonant converter circuit into a single-stage power conversion circuit. Moreover, the coupled inductor of the interleaved buck converter circuit is designed to operate in the discontinuous conduction mode, which can naturally achieve PFC. In addition, the two power switches in the novel LED power supply have zero-voltage switching (ZVS) characteristics, which can reduce the switching losses of the power switches. The two output diodes have the characteristics of zero-current switching (ZCS), which can reduce the conduction losses of the power diodes. This paper developed a single-stage prototype circuit for providing an 144 W (36 V/4 A)-rated LED street-light lamp. According to the experimental results of the prototype circuit with an AC input voltage of 110 volts, the presented single-stage LED power supply offers high power factor (PF &gt; 0.99), low input-current total harmonic distortion factor (THD &lt; 3%), and high efficiency (&gt;89%). In addition, this paper used the built-in Bluetooth wireless communication function of a smart tablet or smart phone to fulfill remote dimming control. By changing the duty ratio of the control signal, we could realize remote dimming control of 20% to 100% of the output LED street-light lamp power.

A Novel Polymorphic Topology with Hybrid Control Strategy Based LLC Resonant Converter for Ultra-Wide Input Voltage Range Applications

To realize effective utilization of renewable energy sources, a novel polymorphic topology with hybrid control strategy based LLC resonant converter was analyzed and designed in this paper. By combining the merits of a full bridge LLC resonant converter, three-level half bridge LLC resonant converter, and variable frequency control mode, the converter realizes an intelligent estimation of input voltage by automatically changing its internal circuit topology. Under this control strategy, different input voltages determine different operation modes. This is achieved in full bridge LLC mode when the input voltage is low. If the input voltage rises to a certain level, it operates in three-level half bridge LLC mode. These switches are digital and entirely carried out by the DSP (Digital Signal Processor), which means that an auxiliary circuit is unnecessary, where a simple strategy of software modification can be utilized. Experimental results of a 500W prototype with 100V~600V input voltage and full load efficiency of up to 92% are developed to verify feasibility and practicability. This type of converter is suitable for applications with an ultra-wide input voltage range, such as wind turbines, photovoltaic generators, bioenergy, and other renewable energy sources.