Half-bridge Converter Research Articles

Double Bus Provider Asymmetrical Half Bridge Converter With a Resonant DCX-Derived Auxiliary Circuit to Supply a LED-Based VLC Postregulator

The wide and settled use of Light-Emitting Diodes (LEDs) in lighting has made Visible Light Communication (VLC) an interesting option. Given the way LEDs are driven in VLC, the Two-Input Buck converter fits perfectly as a post regulator for VLC-LED lamps. Its main drawback is that it needs two input voltages with specific requirements tied to the VLC feature. One needs to be regulated according to the LEDs knee voltage thermal drift, while the other needs to be constant. With the objectives of avoiding complex circuits with cross regulation and using two converters performing the bus provider, the present work proposes a converter with two outputs that meet those voltage requirements. This converter is the integration of an Asymmetrical Half Bridge converter and a resonant unregulated Half Bridge converter. This integration is achieved thanks to the primary side similarity of both converters and the integration of both transformers in one magnetic core, achieving a solution with fewer components. In addition, one output can be fully regulated by a standard control variable while the other remains naturally constant, and is independent from any control variable. This greatly simplifies the control stage, avoiding cross regulation while fully complying with the application requirements. This work presents the circuit concept and how it relates to the intended application. The principle of operation will be explained and used to define the wide operational region where the topology meets the requirements imposed by the application. To validate the proposed topology, a 45-W prototype is built and tested, archiving the output voltage requirements and an overall efficiency near 94%.

Highly Efficient Nonisolated Constant Output Current LCC Resonant Converter With Wide Input Voltage Range

This paper proposes a simple structure highly efficient low-element-count non-isolated constant output current resonant converter for wide input voltage range and high-efficient applications. The converter is developed by combining a basic buck-boost converter with a half-bridge LCC resonant converter to improve the adjustable voltage conversion ratio. In the proposed structure, most of the output power is fed directly, which reduces the conduction power losses and increases efficiency by reduction of the processed power and the switches and rectifier diodes voltage stress is significantly decreased due to cascaded outputs structure. It operates at the resonant frequency to achieve a constant output current feature for applications such as LED drivers and battery chargers and the output current is regulated by the pulse-wide modulation (PWM). The proposed converter can achieve zero-voltage switching (ZVS) operation for all switches and zero-current switching (ZCS) operation for all diodes over a wide range of the input voltage and load conditions. The proposed structure is analyzed in detail. To verify the proposed converter performance, a 21 W laboratory prototype is realized and tested for the wide input voltage range of 12–40 V to provide 350 mA output current. The proposed converter achieves high peak efficiency of 98.15%.

A Fault-Tolerant LLC Converter With High Reliability and Low Cost for Two-Stage Converters

The popularity of electric vehicles is getting higher, and a large number of DC-DC converters are deployed. LLC converters have witnessed a rapid deployment due to their remarkable merits, often employed as the isolation stage in two-stage converters. However, the contradiction between the increasing demand for reliability and the limited space is becoming prominent. Therefore, ensuring fault tolerance capacity with fewer devices is highly desired. A fault-tolerant LLC converter, which can keep working after multiple unexpected faults, is designed to take over half-bridge LLC converters. The pre-fault converter behaves like a full-bridge LLC converter and would be reconstructed to retain uninterrupted power output after faults. The reconstructed converter after the first fault behaves like two parallel half-bridge LLC converters and would be further reconstructed into a single half-bridge converter after the second fault. The faults can both be handled, including short-circuit faults and open-circuit faults. The transition processes of reconstruction are extremely short. The spike current during the transition processes is well limited, and the output voltage has slight fluctuation. The proposed converter could drastically reduce the need for redundancy and has obvious cost advantages. Finally, a prototype is developed to verify the superiority of the proposed converter.

A 99.74% Efficient Capacitor-Charging Converter Using Partial Power Processing for Electrocalorics

This work combines a 99.2% efficient GaN-based low-voltage fast-switching half-bridge converter with a Si-based high-voltage slow-switching and almost lossless switched capacitor multiplexer using a partial power processing approach to a six-level prototype with 99.74% efficiency. A loss breakdown shows how the ideal partial power processing efficiency is theoretically increased to 99.84% by using four additional voltage levels, but then reduced to the measured efficiency by the additional static and dynamic losses of the multiplexer. For electrocaloric heat pumps, an emerging technology for cooling and heating applications with zero global warming potential, such high charging efficiencies enable a high heat pump system coefficient of performance (COP). Based on available data of electrocaloric lead magnesium niobate (PMN)-based samples, and based on a first-principle and best-case analysis for Carnot-like cycles, it is predicted that the 99.74% electrical charging efficiency in combination with the electrocaloric material data enables to surpass 50% of the thermal Carnot limit (for cooling with a heat pump). Ultra-high efficiency of power converters thus pave the way towards future electrocaloric heat pumps of competitive system performance.

An Independently Controlled Two Output Half Bridge Resonant LED Driver

In this research work, an independently controlled two output half-bridge resonant LED driver is proposed. Half bridge series converters will be providing power to two LED lamps. The devices in half-bridge converter are switched at zero voltage using LC resonant circuit. Therefore, switching transition power losses are minimized which increases the LED driver efficiency. Each LED lamp’s ripple current is decreased by adding an inductor in series with it, eliminating the need for an electrolytic capacitor and extending the life of the resonant LED driver. Both regulating and dimming operations use asymmetrical duty cycle (ADC) control. Numerical simulations are conducted to examine the suggested resonant converter topology’s steady state performance as it sources LED applications. Using the OrCAD/PSPICE tool for universal AC mains, 25 W and 29 W LED driver analysis, design, modeling, and simulation are carried out. The proposed driver needs to provide high efficiency even at reduced illumination.

An AC-DC LED Integrated Streetlight Driver with Power Factor Correction and Soft-Switching Functions

The use of light-emitting diodes (LEDs) in street lighting applications has been greatly welcomed with the current trends of energy saving, environmental protection, carbon reduction, and sustainable development. This paper presents a novel AC-DC LED integrated streetlight driver that combines an interleaved buck converter with a coupled inductor and a half-bridge series resonant converter with a full-bridge rectifier into a single-stage power conversion topology with power factor correction (PFC) and soft switching capabilities. The PFC is achieved by designing the coupling inductor in the interleaved buck converter sub-circuit in discontinuous conduction mode. In addition, the resonant tank in the half-bridge series resonant converter sub-circuit is designed to be similar to an inductive load, thus giving the power switch a zero-voltage switching (ZVS) function, decreasing switching losses and increasing the overall efficiency of the proposed circuit. A prototype circuit of the proposed LED integrated streetlight driver with a power rating of 165 W (235 V/0.7 A) and 110 V input utility voltage has been developed and tested. According to the measurement results, a power factor greater than 0.98, a total harmonic distortion coefficient of the input current less than 3%, and an efficiency greater than 89% were obtained in the AC-DC LED integrated streetlight driver. Therefore, the experimental results are satisfactory and demonstrate the functionality of the proposed AC-DC LED integrated streetlight driver.

A Fast Protection Relay for MMC-Based DC Grids Robust to Cyber-Physical Anomalies

Half-bridge modular multilevel converters (HBMMCs) are widely applied in modern DC grids, where converter substations have a cyber-physical structure similar to that of a typical intelligent substation. One major issue for HBMMCs is the lack of sufficient fault interruption capability. Hence, a reliable protection relay is necessary. However, conventional relays need a very robust cyber-physical system, and unintended events are not rare in intelligent substations. In this paper, several types of cyber-physical anomalies and their impacts on protection relays are first analyzed. Then, a novel protection relay is proposed based on the difference between the theoretical and the calculated modal measurements. To eliminate inter-substation asynchronization, the Bhattacharyya distance is introduced to quantify the above graphic feature in a sliding time window with high robustness to noise contamination; also, historical data is employed to identify and erase upcoming abnormal samples in real time. Case studies validate the robustness against external faults, power order change, and cyber-physical anomalies. Additionally, the proposed protection relay is highly sensitive to internal faults. Discussions are also conducted to investigate the quantitative capability against abnormal samples, to determine the scope of applications for different DC lines and to compare the proposed protection relay with several state-of-the-art methods.

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.

Characteristics analysis of micro-source half-bridge converter series Y-connection based microgrid systems

Characteristics analysis of micro-source half-bridge converter series Y-connection based microgrid systems

Impedance Phase Based Active Injection Protection for Radial VSC-HVDC Grid

Effective DC fault identification is very important for a half-bridge modular multi-level converter (HB-MMC) based high voltage direct current (HVDC) grid. The performance of the traditional protection principles lacks reliability and sensitivity, and there is a further limitation under the current limiting strategies. To address the problem, a scheme coordinating the control and protection is proposed, which actively creates the known feature for fault identification and limits the fault current at the same time. In this paper, the characteristics of the input impedance phase under different faults are analyzed in various frequency bands. Based on the analysis of the input impedance phase, the converter switches the control mode and generates a characteristic signal at a particular frequency after fault detection. Then, the Prony algorithm is employed to acquire the phase information at the injection frequency. Finally, the faulty zone can be identified by the value of the input impedance phase. This active injection protection scheme is applicable to identify different faults, verified in PSCAD/EMTDC, and tested by hardware-in-the-loop simulation in RTDS.

Optimization of Power Sharing and Switching Frequency in Si/WBG Hybrid Half-Bridge Converters Using Power Loss Models

The Si/WBG hybrid half-bridge (HHB) coordinates the hybrid-frequency operation and power-sharing ratio between the low-frequency Si phase and the high-frequency WBG phase to offer the same WBG benefits but with a much-reduced cost, in comparison to a full WBG solution. However, no generalized methodology has been reported so far to realize the full-scale optimization of switching frequency and the power-sharing ratio between those phases. In this paper, we first develop a generalized power loss model for Si/WBG HHB with total power loss as output and switching frequency and power-sharing ratio as a continuous input variable. And then develop a dynamic power-sharing ratio and switching frequency control to achieve minimum power loss over a wide load range. A 3-kW prototype of the Si/SiC HHB-based DC/DC converter is built to validate the power loss model and proposed control strategy. In comparison with several fixed parameters, the dynamic parameters obtained by the proposed power loss model achieve a 6-18% total power loss reduction without sacrificing power quality performance.

Control strategy for plug-in electric vehicles with a combination of battery and supercapacitors

Abstract Research proposes an optimal power distribution approach for application of electric vehicle (EV) with use of hybrid energy storage system (HESS). HESS protection structure includes dual isolated-based soft-switching symmetrical coupling with half-bridge bidirectional converters to the system of battery and supercapacitors (SCs). The bidirectional converter properly controls the charging process of the battery and SC as well. Besides, spiral wound SCs of mesoporous electrode material have been used in EVs. In the drive cycle of EVs, the operation of SC relates to the functionality of the allocated scheme under “peak load transfer” at 2i sc ∼ 3i bat current profile carried out. New energy allocation strategies under SOC control enable SC charging and discharging at peak currents of around 4i bat. The comparison of the mode of the battery system showed that the performance acceleration built under EVs has been improvised at a certain rate of 50% with a loss of energy minimised to 69%. As a result, the technique adapts different load curves, thus enhancing the utilisation of energy with reduced aging of the battery. The simulation results show that the proposed scheme meets the power demand of a typical driving cycle, for testing vehicle performance, and various energy management system have been assessed based on hydrogen consumption, overall efficiency, state of charge of SCs and batteries, stress on hybrid sources, and DC bus stability. The proposed strategy reduces hydrogen consumption by 8.7% compared to other strategies.

Direct Instantaneous Torque Control of SRM Based on a Novel Multilevel Converter for Low Torque Ripple

The torque ripple of a switched reluctance motor (SRM) limits its application in electric vehicles. This paper proposes a DITC system for SRMs based on a novel multilevel converter (MLC), which aims at the problem that the torque ripple cannot be effectively suppressed for the conventional direct instantaneous torque control (DITC) of an SRM due to the limitation of the DC bus voltage in the asymmetric half-bridge converter (AHBC) and the single control strategy formulated in the commutation region. Based on the advantages of fast excitation and fast demagnetization for the proposed MLC and the torque distribution characteristics for each phase winding in the commutation region, a novel torque hysteresis control strategy is developed to improve the torque-following ability of the DITC and achieve the purpose of minimizing the torque ripple in the commutation region. In addition, multiobjective optimization control of the motor is carried out to improve the efficiency of the DITC system while suppressing the torque ripple. The effectiveness of the proposed SRM drive scheme is verified by experiment, which is of great significance for the application of SRMs in electric vehicles.

Bipolar power converter and control of switched reluctance generator system for renewable energy storage

PurposeBecause of the shortage of energy, the development of green and reliable energy is particularly important. As a green and clean energy, wind power is widely used. As the core component of wind power generation, it is particularly important to choose generators with high reliability. Switched reluctance machine is widely used as generators because of its strong fault tolerance and high reliability. Therefore, this paper aims to propose a power converter and its control strategy to improve the efficiency of switched reluctance generators.Design/methodology/approachIn this paper, a full-bridge power converter (FBPC) instead of the asymmetric half-bridge power converter (AHBPC) is adopted to drive the switched reluctance generator (SRG) system. Compare the FBPC with the AHBPC, the FBPC has several advantages including low cost and modularization, and operation process of SRG winding current direction is variable.FindingsThe results show that the SRG system can keep smooth operation by the FBPC with relatively high efficiency.Originality/valueThe FBPC is suitable to drive the SRG system. Meanwhile, this paper introduces two excitation modes of the FBPC as three-phase three-beat mode and six-phase six-beat mode. When the six-phase six-beat control strategy is adopted, the dead band time of the converter can be avoided. At the same time, the SRG has higher efficiency.

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.

Reliability evaluation on SRG with full-bridge power converter considering thermal stress

PurposeQuantitative reliability analysis can effectively identify the time the driving system needs to be maintained. Then, the potential safety problems can be found, and some catastrophic failures can be effectively prevented. Therefore, this paper aims to evaluate the reliability of the switched reluctance generator (SRG) driving system.Design/methodology/approachIn this paper, a method considering different thermal stresses and fault tolerance capacity is proposed to analyze the reliability of an SRG. A full-bridge power converter (FBPC) instead of the asymmetric half-bridge power converter (AHBPC) is adopted to drive the SRG system. First, the primary fault modes of the SRG system are introduced, and a fault criterion is proposed to determine whether the system fails. Second, the thermal circuit model of the converter is established to quickly and accurately obtain the junction temperature of the devices. At last, the Markov models of different levels are established to evaluate the reliability of the system.FindingsThe results show that the two-level Markov model is the most suitable when compared to the static model and the one-level Markov model.Originality/valueThe driving system of SRG will be more reliable after the reliability of the system is evaluated by the Markov model. At the same time, an FBPC is adopted to drive the SRG. The FBPCs have the advantages of fewer switching devices, higher integration and lower cost. The proposed driving strategy of the FBPC avoids the current reversal and the generation of dead zone time, which has the advantage of reliable operation. In addition, a precise thermal circuit model of the FBPC is proposed, and the junction temperature of each device can be obtained, respectively.

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.

Meta Heuristic Optimization Algorithm based Rectifier Control in Switched Reluctance Generator

A simple, robust, economical and highly efficient 8/6 switched reluctance (SR) generator is connected to a wind turbine to increase the amount of power extracted from the wind. Output power of the generator is fed to the PWM rectifier via a four-phase asymmetric half-bridge (AHB) converter and maximum power point tracking (MPPT) of the rectifier is assisted with torque ripple minimization to present an effective control as it allows torque ripple suppression arising from the SR generator nature while capturing maximum wind power. The wide range of speed variation of the SR generator is minimized using the combination of PI and hysteresis current controller. Further, the output of the AHB converter is directed to the conventional PWM rectifier. The purpose of this research is to deliver ripple-free dc power to a dc grid/load or battery. Hence, in this paper, the GWO-based optimized PI controller is implemented as an MPPT method to maintain the constant dc bus voltage. The inherent ability of GWO optimization-based control of the rectifier system ensures better dynamic control. The simulation is performed in a MATLAB environment for a power rating of 1000W standalone system and tested using an FPGA controller. This paper carries out a stability analysis of the system by varying the wind velocity.

Adaptation of Inductive Power Transfer to Small Household Appliances That Can Operate on Induction Heating Cooktops: Wireless Electric Kettle

In this paper, an inductive power transfer (IPT) system without compensation elements is presented for small house appliances. The proposed system’s transmitter side is an independent induction heating cooktop. IPT can be achieved when the kettle with the receiving coils is placed on the transmitter coil. The coils are designed with a high coupling coefficient. The magnetic system model consisting of aligned transmitter and receiver coils is created in the Maxwell program. In the created model, the analysis depends on the air gap and frequency, which are the variables that affect the wireless power transfer. The electronic circuit simulation uses the coil model to examine the system’s dynamic behavior. The design of the transmitter/receiver coils of the IPT system is made with a cylindrical coil with a diameter of 145 mm, taking into account that it is compatible with the dimensions of the existing kettle and induction heating cooktops coil. A half-bridge series resonant converter circuit is used to adjust the power transferred to the load. To verify the simulation results and test the designed system, an experimental circuit using a 2200 W kettle is carried out. In the experiments, the air gap between the coils is kept constant at 7 mm, and measurements are taken for different powers. Experimental results confirm the magnetic model and simulation results. As a result, wireless power transfer is realized in a wide range without loss of performance in the kettle. System efficiency is greater than the 90% specified in the Ki cordless kitchen standard, and the harmonic currents drawn from the mains are lower than the values determined by the IEC 61000-3-2 standard.

A Closed-Loop High-Frequency Current Shaping Method to Achieve Trapezoidal Transformer Current in a Current-Fed Dual Active Half-Bridge Converter for Minimum RMS Current and Wide-Range ZVS

This article proposes the use of primary and secondary side duty ratio control along with the phase shift control in a current-fed dual active half-bridge (DAHB) converter to achieve trapezoidal transformer current, which results in zero voltage switching (ZVS) of all the switches and minimum rms current even at light loads, for a wide range of input voltage. The high-frequency transformer current is directly sensed at specific transition instants by a delay-adjusted sampling strategy to be used as control variables in a current control structure. This is better because the voltage control of capacitor voltages would have required more expensive sensors. A simple and accurate small-signal model of the converter is developed, and the relevant transfer functions are derived. The controller design details are provided. Finally, experimental results on a 1-kW laboratory prototype demonstrate the effectiveness of the closed-loop duty ratio control in achieving trapezoidal transformer current resulting in improved efficiency and ZVS of the switches, compared to a simple phase shift control.