Half-bridge Converter Research Articles

A Comprehensive Performance Comparison between Segmental and Conventional Switched Reluctance Machines with Boost and Standard Converters

This paper presents the comparisons between two types of switched reluctance machines (SRMs) and SRM converters. An SRM with a segmental rotor is compared with a conventional SRM (CSRM), and an SRM converter containing a passive boost circuit is compared with a conventional asymmetric half-bridge (AHB) converter. The segmental SRM has an asymmetric rotor with a segmented structure. The four rotor segments are made of steel laminations. Two segments are misaligned with the other two by 15 degrees. The torque ripple of the SRM with this structure is decreased, and the static torque is increased compared to a conventional SRM. The boost converter comprises a front-end circuit and a conventional AHB converter. The front-end circuit boosts the voltage level. The boosted voltage accelerates the rising and falling progress of the phase current. In this way, the SRM can obtain a greater speed and a smaller torque ripple. The comparison is conducted in simulation and validated through the experimental results. The experiment results have demonstrated that the segmental SRM obtains a maximum 7% torque ripple reduction at a low-speed range, compared to the CSRM. With the boost converter, both the CSRM and the segmental SRM can achieve a lower torque ripple and a higher maximum speed.

Gate-Source Voltage Analysis for Switching Crosstalk Evaluation in SiC MOSFETs Half-Bridge Converters

Measuring the gate-source voltages of wide bandgap (WBG) devices in half-bridge converters provides useful information about susceptibility to crosstalk, which can cause uncontrolled cross-conduction and excessive gate-oxide stresses. However, parasitic elements of the printed circuit board (PCB) and device packaging can compromise measurement accuracy, causing unreliable results. Here we describe how this shortcoming can be addressed using devices in packages that have a Kelvin source pin, allowing a more accurate analysis.

High-Efficiency Asymmetrical Half-Bridge Converter With Linear Voltage Gain

A conventional asymmetrical half-bridge (AHB) converter is one of the widely used topologies in low to medium power applications. However, when it is designed in a wide input voltage range, it operates with a low duty ratio at nominal input voltage. In addition, it has disadvantages, such as a dc offset of magnetizing current, an unbalanced average current of the diode, and a nonlinear voltage gain due to asymmetrical operation. To solve these disadvantages, an AHB converter with linear voltage gain is proposed. The proposed converter has a structure in which a capacitor is added as a voltage source to obtain a symmetrical operation by extending the commutation period. Therefore, it has a narrow range of operating duty ratio and a zero dc offset of magnetizing current. Due to the zero dc offset of magnetizing current, it has a small size transformer and improved zero-voltage switching conditions of the primary-side switches. In addition, it has a low primary rms current and a balanced average current of the diode. Consequently, the proposed converter has high efficiency under the entire load conditions. A 300–400 V input and 48 V/400 W output prototype is tested to verify the feasibility of the proposed converter.

A Series Resonant Three-Port DC–DC Converter With Decoupling Function and Magnetic Integration

In this article, a new resonant three-port dc–dc converter with dual half bridges plus one full bridge is proposed, which can realize bidirectional power flow between each port. The resonant capacitor has three functions in the circuit: the resonant capacitor can improve the magnetic bias of half bridge converter, and therefore, the transformer saturation can be avoided; the resonant capacitor is introduced to make the inductor current close to sine wave, so that the eddy current loss of the transformer can be reduced; by setting the resonant frequency of one of the three ports equal to the switching frequency, the mutual interference between the other two ports can be reduced, so that the hardware decoupling effect is achieved. First, the operation principle of the three-port converter is analyzed. Second, the steady-state model of the converter is established, and the power transmission characteristics and soft-switching characteristics are analyzed. Third, the cause of the power coupling between ports is analyzed and the hardware decoupling method is proposed. Finally, the number of magnetic elements is reduced through magnetic integration, and the correctness of the theoretical analysis is verified by simulation and prototype experiments.

Fault Diagnosis for Power Converter in SRM Drives Based on Current Prediction

This article proposes an online diagnosis scheme for transistor faults of asymmetric half-bridge converter (AHBC) in switched reluctance motor (SRM) drives. In order to extract more information from the phase current to identify faults, based on the conventional current measurement method, two novel current measurement methods are presented by reconstructing current sensors. According to the novel current measurement methods, a current prediction method is raised. The phase current at the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> th sampling time is available so that the estimated current can be calculated. The fault can be detected and located by analyzing the given and actual switching states, which are deduced by comparing the measured and estimated currents. Compared with existing methods, the proposed scheme can be applied to diagnosis of multiple faults in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -phase AHBC, which can operate at various control strategies and chopping modes. With a single current sensor in each phase, the scheme will not increase the cost and complexity of the SRM drive. Furthermore, the scheme does not require complicated computation, making it easy to implement online. The experimental results confirm the effectiveness and flexibility of the proposed scheme.

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.

Design and implementation of real-time simulation module for non-isolated bidirectional half-bridge DC–DC converter

With the rapid development of new energy technology, the number of grid-connected systems and switching control frequency are also increasing. It makes the operation state of the power grid more complicated. Therefore, a small step real-time model is urgently needed to monitor the operation of power grid. Based on the existing computing hardware, FPGA has the characteristics of high concurrency and multi-pipeline computing, which ensures the real-time performance of the simulator. Because non-isolated bidirectional half-bridge DC–DC converter is widely used in power grid system, the real-time simulation design based on FPGA is carried out in this paper. This paper proposes an improved Associated Discrete Circuit (ADC) method and derives the formula of the optimal conductivity parameters. By using the transient initialization method, the accuracy of the ADC modeling method is promoted. The simulation model of the non-isolated bidirectional half-bridge converter is built on FPGA with a time-step of 1μs. Under the premise of real-time performance, the relative error of the proposed simulation module is controlled at about 3%.

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.

Quantitative Modeling and Analysis of Switching Oscillations of Cascode GaN Devices in Half-Bridge Converters

Having high efficiency and power density, the motor drives based on wide bandgap (WBG) devices can better meet the requirements for developing more electric aircraft (MEA). However, the fast switching characteristic of gallium nitride (GaN) devices has led to undesirable voltage and current oscillations during turn-ON and turn-OFF processes, thus decreasing the reliability of the electric drive system. The complicated structure of cascode GaN devices and various parasitic parameters in the device and the half-bridge converter make the switching oscillation modeling of cascode GaN device comparatively complex. In this article, an equivalent circuit approach in consideration of nonlinear characteristics in voltage-dependent junction capacitances is presented to model the switching oscillation for high-voltage (650 V) cascode GaN-based half-bridge converters. Quantitative mathematical models are derived to provide a theoretical analysis of the switching oscillation for turn-on and turn-off processes of cascode GaN devices. Furthermore, the influences of device and circuit parameters on the oscillation are investigated in detail, offering a reliable guidance to the gate driver and print circuit board design. Finally, experimental studies on the basis of cascode GaN and custom cascodes are carried out to validate the modeling approach. The results have proved that one of the root causes of the oscillations is how the different parasitics interact.

AlScN-Based SAW Magnetic Field Sensor for Isolated Closed-Loop Hysteretic Current Control of Switched-Mode Power Converters

This letter uses a surface acoustic wave magnetic field sensor for measurement and closed-loop current control of the inductor current in a GaN-based dc-dc power converter. The sensor is based on aluminium scandium nitride thin films with relatively high Sc concentration of 32% and fabricated on low-cost 8-in silicon substrate, with a magnetostrictive FeCoSiB film on top of a SAW delay line. The device has dc and bidirectional current measurement capability (derived from the magnetic flux density around a current trace) and is operated electrically isolated above the current trace. With permanent magnets as magnetic bias, the setup has a usable bidirectional current range of ±5 A. A phase detector IC measures the phase shift between the 296 MHz, 19 dBm input, and 35 dB attenuated output signal of the delay line sensor. The active sensor area has a distance of 2.5 mm from the current trace. In a 1.2 mT bias, the sensor is operated with a sensitivity of 18.28°/mT and bipolar current range of up to ±5 A. The sensor signal is enhanced by an analog filter to compensate the over 1 µs delay from the delay line and readout circuit. Finally, the sensor is used as the input of an analog hysteretic current control loop. The closed-loop current control operation is demonstrated using a 48 V GaN-based half-bridge dc-dc converter with 16 kHz triangular inductor current.

Comprehensive Review of Solid State Transformers in the Distribution System: From High Voltage Power Components to the Field Application

This paper presents a systematical and progressive appraisal of the technology since the inception of AC-AC conversion, which is seen to be an indispensable and vital for the advancement of the Solid State Transformer (SST) in a distribution system. Special attention is given to the concepts/topologies and architecture of the SST, the DC-DC conversion devices in the isolation facet, the inversion gadget in the bridge arrangement and their integration in the development of an economically viable and efficient SST design. For the purpose of this article, a number of research papers, research proposals and research dissertations/studies have been accessed that mostly cover work related to this device and brief discussions about several aspects. The various sections of this article are correspondingly devoted to the review of SST design and its various configurations, the significant stages of the DC-DC converter from a transformer-specific perspective and lastly the high-frequency inverter. In critical appraisal, the SST in a three-stage perspective, the dual half-bridge converter and high-frequency half-bridge inverter are the most viable and promising means, offering tremendous advantages over other configurations with emphasis on economy, high flexibility and control performance; thereby weighed as the most workable, practical and realistic solutions. The foremost potential application of this expedient includes a vital component of the power grid.

Monopolar Fault Reconfiguration of Bipolar Half Bridge Converter for Reliable Load Supply in DC Distribution System

This article proposed the concept of monopolar fault reconfiguration for bipolar dc distribution system realized with Bipolar Half Bridge (BiHB) converter. Monopolar fault reconfiguration oriented from bipolar high voltage direct current (HVdc) transmission grid. For dc distribution, the operation aim is to provide uninterrupted power supply to critical load under monopolar fault. It requires interfacing circuit with fault-tolerant capability as well as control design considering both bipolar and monopolar working mode. The proposed BiHB converter achieves mode switching by reconfiguring the converter switching pattern. Considering both monopolar and bipolar working mode, a bipolar modulation method is proposed for coordinate circuit design. Key influence factors relating to the transient voltage spikes have been identified, including the fault detection delay and the modulation method. Besides, to suppress the voltage spikes caused by monopolar fault, feed-forward compensation is adopted for smooth mode transition. The proposed BiHB converter and control strategy have been comparatively evaluated under fault protection and restoration. Uninterrupted power supply of load has been attained, in validation of the proposed monopolar fault reconfiguration concept.

Inertia emulation with the concept of virtual supercapacitor based on SOC for distributed storage systems in islanded DC microgrid

One of the main crises that the world will face is the over pollution of the environment due to the use of fossil fuels. This problem will be solved by replacing renewable energy sources (RESs). DC microgrids (DCMGs) provide the ability to exploit all the potential of RESs. But, high penetration of these sources reduces the inertia and damping of the DCMGs. Therefore, it makes DCMG vulnerable to fluctuations and disturbances. This challenge can be addressed by using distributed energy storage systems (DESS) in DCMGs and inertial simulations. To improve the inertia as well as to balance the charge/discharge of the DESS, the concept of a virtual supercapacitor based on the state of charge (SOC) is introduced. Under the proposed control strategy, DCMG inertia is provided and the SOC balance is maintained in charge and discharge mode. Due to the bidirectional power transmission capability, symmetrical structure and considering the protection purposes of dual half-bridge converter (DHB) can be selected. A small signal has also been investigated to analyse the role of virtual inertia in stability. The simulation results in MATLAB/Simulink show the correct performance dynamics and high impact of the proposed scheme compared to conventional schemes.

Zero-Voltage Switching Full-Bridge Converter With Reduced Filter Requirement and Wide ZVS Range for Variable Output Application

In this article, a novel zero-voltage switching (ZVS) full-bridge converter is proposed to overcome the disadvantages of traditional phase-shifted full-bridge (PSFB) converter. In the proposed converter, a half-bridge (HB) converter with center-tap rectifier (CTR) is integrated into the traditional PSFB converter by sharing the lagging-leg switches and output filter. The HB converter operates with full duty cycle to ensure continuous energy transmission and the output voltage is regulated by adjusting the phase-shifted time of full-bridge (FB) converter. The proposed converter has many advantages such as reduced filter requirement, wide ZVS range and low primary circulating current. In addition, the rectifier in the proposed converter is composed of a full-bridge rectifier section and a CTR section. This feature makes the proposed converter well appropriate for the medium output voltage applications. Key operation principle and characteristics are fully discussed in this article. The effectiveness of proposed converter is verified using a 1.2 kW prototype circuit with 280 V input voltage and 60–120 V output voltage.

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.

Bidirectional Resonant Converter With Minimized Switching Loss Over Wide Operating Voltage Range

In this article, we propose a bidirectional resonant converter having minimized switching loss in a wide operating voltage range. This converter serves as a pulse-width-modulation (PWM) full-bridge resonant-boost converter in the forward operation and a PWM half-bridge resonant-buck converter in the reverse operation. It can then achieve wide voltage gain range even in the reverse operation. By employing a T-type active voltage doubler, we can attain almost zero voltage switching at the turn-off instants, and so switching loss occurred at all active switches becomes negligible. Moreover, the circuit experiences very little instantaneous reactive current under wide voltage variations. Therefore, the proposed converter can accomplish a wide range of voltage gains in both power flow directions and high efficiency over a wide range of operating voltages. We present circuit operation and steady-state analysis in detail. We built a 3.3-kW/400-V prototype that copes with 250~415 V inputs and tested to demonstrate the superior quality of its circuit design.

An Improved Submodule Topology of MMC With Fault Blocking Capability Based On Reverse-Blocking Insulated Gate Bipolar Transistor

The missing capability of DC fault current limitation is an inherent disadvantage in the typical half-bridge modular multilevel converter (MMC), which restricts its application in long-distance high voltage direct current (HVDC) systems. The full-bridge submodule (FBSM) and clamped double submodule (CDSM) topologies allow for fault current self-clearing, but also suffer from additional hardware cost and power losses. In this paper, an improved submodule topology utilizing the new reverse-blocking insulated gate bipolar transistor (RB-IGBT) is proposed to improve system economy without compromising its performance. The operating principles and DC fault characteristics of the proposed topology are analyzed in details, including comparison with various topologies in terms of cost, losses, fault current clearing speed and thermal. Compared with the traditional CDSM topology, the proposed RBSM can clear DC faults faster with reduced cost of switching devices. A DC fault protection strategy for MMC-HVDC system is also presented. Simulation results under normal operating, permanent and transient fault conditions are carried out to verify the effectiveness of the proposed topology.

Single-Phase Isolated AC-AC Converters Based on the Dual Active Bridge Converter

This article presents three single-phase isolated ac–ac converters based on the dual active bridge (DAB) converter and interleaved transformers. The structures allow obtaining filter elements with reduced dimensions, as well as bidirectional power flow and high efficiency over a wide load range. Multilevel voltage waveforms exist in the input and output sides of the symmetrical converters, resulting in reduced harmonic content. The possible arrangements include a symmetrical half-bridge converter (SHBC), a symmetrical full-bridge converter (SFBC), and a symmetrical interleaved full-bridge converter (SIFBC). The introduced topologies can be regarded as prominent solutions for applications involving solid-state transformers, dynamic voltage restorers, and uninterruptible power supplies. A thorough mathematical analysis of the SHBC is carried out and experimental results are presented to investigate the converter performance in steady-state and transient conditions.

PV based electric vehicle battery charger using resonant converter

PV based electric vehicles battery charging voltage is regulated using converter to the desired range using power electronic converters. The power which is extracted from the solar panel is stored in batteries using a half-bridge resonant converter. A resonant LC converter with soft-switching provides good voltage regulation and better efficiency at high frequency of operation. During the battery operation, the mode of operation is decided by the state of charge of the battery. The battery is charged at a regulated voltage level at a constant current even when the input voltage is varied from the PV panel. The experimental results were validated to prove its performance using 30W solar panel connected with a 24W LED lamp and a battery of 26 Ah.