Showing papers on "Rectifier published in 2021"

Compact Dual-Band, Wide-Angle, Polarization- Angle -Independent Rectifying Metasurface for Ambient Energy Harvesting and Wireless Power Transfer

Abstract: A dual-band and polarization-angle-independent rectifying metasurface (MS) with a miniaturized dimension and a wide incident angle range are presented in this article. The proposed structure consists of a single layer of periodic cell arrays with integrated diodes, a $dc$ feed, and a load. A novel method of incorporating surface-mount components (e.g., diodes) into the texture is developed to simplify the structure. The matching network between MS and the nonlinear rectifier can be eliminated directly due to the multimode resonance and adjustable high-impedance characteristics of the MS. Moreover, the proposed MS can maintain high conversion efficiency by using different diodes without changing the overall topology. In addition, the proposed design can effectively capture incoming waves with arbitrary polarizations and a wide incident angle range of 60°. The $4\times 4$ MS array is fabricated and measured. Experimental results show that the proposed structure can achieve maximum efficiency of 58% at 2.4 GHz and 50% at 5.8 GHz with an input power of 0 dBm under different polarizations and incident angles. Importantly, it is also shown that the rectifying MS can maintain high efficiency over a wide power range from −3 to 10 dBm. The proposed design concept is very suitable for the adaptive wireless power supply of portable devices.

Omnidirectional Dual-Polarized Low-Profile Textile Rectenna With Over 50% Efficiency for Sub- μ W/cm 2 Wearable Power Harvesting

Abstract: Despite the recent advances in textile antennas, in complete systems such as a rectenna, the efficiency of fully textile solutions has been over 46% lower than hybrid textile/rigid implementations. This article presents a fully textile rectenna for ultralow-power sub- $\mu \text{W}$ /cm2 applications. A dual-polarized omnidirectional low-profile textile antenna is presented. The rectenna is based on a compact inductively matched rectifier. The textile-based rectifier occupies 0.22 cm2 and achieves a state-of-the-art power conversion efficiency (PCE) of 41.8% at −20 dBm, at 820 MHz, despite its lossy substrate. A triple-band rectifier is then designed and fabricated to show the scalability of the matching approach. The rectifier is characterized using a new figure of merit “average PCE” over a time period while charging a capacitor. Time-varying S-parameters are used to quantify the impact of the capacitor’s charge on the impedance matching. The rectifier directly charges a 1.32 mF capacitor up to 1 V in 0.41 and 4.5 s from 10 and 0 dBm, respectively. Wireless testing of the proposed rectenna demonstrates over 50% and 40% (PCE) below $1~\mu \text{W}$ /cm2 in space and on-body, respectively. The rectenna efficiently receives power from mismatched polarization and with a 360° half-power beamwidth.

A Multiport DC–DC Converter Based on Two-Quadrant Inverter Topology for PV Systems

Abstract: This article presents an isolated high-frequency (HF) multiport dc–dc converter for photovoltaics (PV) interfacing systems In the proposed multiport converter, an HF transformer with multiple input windings and single output winding is utilized Each input port is based on a proposed two-quadrant inverter topology, which connects a PV module to the HF transformer The output port is tied to a dc bus using a rectifier The proposed two-quadrant inverter topology prevents current flow from the ac side to the dc side This action prevents circulating currents between different ports Each two-quadrant inverter is controlled to harvest maximum power from its associated PV module The analysis and operation scenarios of the proposed multiport converter are discussed PSCAD/EMTDC software package is used to simulate the proposed PV interfacing system to investigate the operation of the proposed multiport converter topology and to examine the dynamic system behavior In addition, an experimental prototype is developed to validate the operation scenarios of the proposed multiport dc–dc converter and to examine the performance of the presented PV interfacing system

Power Density Optimization of 700 kHz GaN-Based Auxiliary Power Module for Electric Vehicles

Abstract: This article proposes a high-power density 1.8 kW auxiliary power module (APM) for electric vehicles (EVs) based on gallium nitride devices. A design procedure for the high-frequency phase-shift full-bridge with current-doubler rectifier using printed circuit board (PCB)-based planar magnetics is proposed. Leakage inductance analysis of the high-frequency pulsewidth-modulation converter is given to achieve both regulation and zero-voltage-switching turn- on . Then, the magnetics optimization procedure for the customized planar core is proposed with a magnetic figure-of-merit concept to meet the high-power density target. Technical considerations are detailed to meet the extreme temperature constraint imposed on the EVs components. Finally, the proposed APM is demonstrated with a switching frequency of 700 kHz and a power density of 8.1 kW/L (132.8 W/in3).

Biotelemetry and Wireless Powering of Biomedical Implants Using a Rectifier Integrated Self-Diplexing Implantable Antenna

Abstract: This article proposes an efficient and complete wireless power transfer (WPT) system (WPTS) for multipurpose biomedical implants The WPTS is composed of a self-diplexing implantable antenna, efficient rectifier, and WPT transmitter (WPT Tx) The proposed system is capable of simultaneously transmitting recorded data and recharging the batteries of the devices (so as to elongate the implant life) The WPT Tx occupies dimensions of $50 \times 50 \times 16$ mm3 and is optimized to effectively transfer power at 1470 MHz to a 55-mm deep implantable device An efficient and compact ( $34 \times 67$ mm2) rectifier is used at 1470 MHz to convert the harvested RF power into a useful direct current (dc) power The proposed rectifier circuit exhibits a high conversion efficiency of 50% even at an input power of −14 dBm and maximum efficiency of 761% at 2 dBm The proposed self-diplexing implantable antenna occupies small dimensions (94 mm3) and operates at 915 and 1470 MHz by exciting ports 1 and 2, respectively The biotelemetry operation is performed using a 915 MHz band (port 1), and the rectifier circuit is connected to port 2 (1470 MHz) to perform wireless powering The simulated results are validated by examining the individual elements (WPT Tx, rectifier, and self-diplexing antenna) and overall WPTS in a saline solution and minced pork The results prove that the proposed scheme is suitable for biotelemetry and wireless powering of biomedical implants

LCCL-LC Resonant Converter and Its Soft Switching Realization for Omnidirectional Wireless Power Transfer Systems

Abstract: Recently, omnidirectional wireless power transfer (WPT) systems have been studied intensely, due to their improved flexibility as compared to their planar counterparts. The LCCL-LC resonant converter topology is selected due to its current source characteristics in this article. The system frequency is pushed to megahertz (MHz) to increase the spatial charging freedom. In a megahertz WPT system, the reactance of the full bridge rectifier can no longer be neglected; therefore, an analytical model of the full bridge rectifier input impedance is built. Furthermore, zero-voltage switching (ZVS) of the switching devices is essential in reducing the switching loss and noise in a megahertz system. A design methodology of the LCCL-LC circuit is proposed to achieve the ZVS operation in the case of one transmitter and one receiver. Then, the ZVS analysis is extended to the scenario of multiple transmitter coils and one receiver coil. Finally, a 6.78-MHz wireless charging system is built according to the proposed design methodology. Experimental results validate the accuracy of the ZVS analysis, and the ZVS operation is well achieved under different coupling and load conditions. The peak system efficiency of 82% at 5-W output power is achieved.

A Dual-Sided Control Strategy Based on Mode Switching for Efficiency Optimization in Wireless Power Transfer System

Abstract: Transfer efficiency of a wireless power transfer (WPT) system is tightly related to the load, which varies greatly in a wide range during the charging process. Generally speaking, dual-sided control strategies are commonly applied to overcome the load variation and improve system efficiency. However, the system may suffer from hard switching, high control complexity, and auxiliary dc/dc converters. In this article, a dual-sided control strategy based on mode switching is proposed to approach an optimal load impedance, zero-voltage switching of all mosfet s in WPT system, and a required output. In this control strategy, the output voltage of the inverter is adjusted in a wide range by switching the operation mode of the inverter to approach the optimal load impedance. The output current/voltage is regulated by the active rectifier control. Besides, a novel phase-locked method is proposed for the semi-bridgeless active rectifier control, which is simpler compared with the traditional phase-locked method. Finally, a 500-W prototype is built to verify the theoretical analysis, and the peak system efficiency of 93.9% is gained with k = 0.23.

An On-Board Charger Integrated Power Converter for EV Switched Reluctance Motor Drives

Abstract: This article presents a power converter topology with integrated driving and charging capability of switched reluctance motor (SRM) drive for electric vehicle (EV) application. In the driving mode, the bus voltage can be adjusted flexibly by the front-end buck converter, which meets the requirements of the speed open-loop and closed-loop control. Besides, higher voltage demagnetization can be achieved by connecting the upper freewheeling diodes of the asymmetric half-bridge converter to the battery bank, thus can accelerate the demagnetization process, extend the dwell angle, and enhance the output of the motor. In battery charging mode, a bridgeless rectifier converter is constructed by utilizing two-phase windings of the SRM and the existing power devices of integrated power converter, without additional inductors and charging units. The battery charging and power factor correction control can be realized by closed-loop control of charging current. Detailed analysis and experiments on a 1 kW 12/8 structure prototype SRM validate the effectiveness of the proposed technologies.

Current-Source Inverter Integrated Motor Drives Using Dual-Gate Four-Quadrant Wide-Bandgap Power Switches

Abstract: Four-quadrant (FQ) switches that have both bidirectional current and reverse-voltage blocking (RVB) capabilities are appealing candidates for use in current-source inverters (CSI) to significantly reduce the switch conduction losses. However, the FQ characteristics of these switches can create problems during switching events by causing transient overcurrent pulses that damage the inverter. Commutation methods for FQ switches in CSI topologies that address these challenges are presented in this article. Several key aspects of the performance and implementation of these commutation methods are explored for a high-power density 3 kW integrated motor drive incorporating both a current-source active rectifier and inverter stage that has been developed using these FQ switch methods. Experimental results demonstrate the benefits of implementing these commutation methods in CSIs that use FQ switches. The benefits include substantial efficiency improvement compared to the conventional CSI implemented with series power diodes as well as reduced mass and volume of passive components due to the high switching frequency (100 kHz).

Analysis of Impedance Tuning Control and Synchronous Switching Technique for a Semibridgeless Active Rectifier in Inductive Power Transfer Systems for Electric Vehicles

Abstract: In inductive power transfer (IPT) systems, load, and magnetic coupling variations cause an impedance mismatch. Impedance mismatch is one of the most serious problems in IPT systems for electric vehicles (EVs) because an EV is not always parked in the same location. Therefore, an impedance tuning control for semibridgeless active rectifiers (SBARs) is proposed in this article to compensate for this mismatch. The proposed impedance tuning control is achieved by adjusting the turn- on point and duty of the SBAR without using any additional component. Moreover, a technique for detecting the voltage-rising edge of the SBAR switch is proposed to extract the switching frequency and to synchronize the SBAR with the primary system. A 3.3-kW prototype of the IPT system with the SBAR is manufactured, and the proposed impedance tuning control is verified through experimental results according to the coupling coefficient. The proposed control can achieve an efficiency improvement of 6.4% under the impedance mismatch.

Maximum Power Point Tracking for Wind Turbine Using Integrated Generator–Rectifier Systems

Abstract: Offshore wind is a rapidly growing renewable energy resource. Harvesting offshore energy requires multimegawatt wind turbines and high efficiency, high power density, and reliable power conversion systems to achieve a competitive levelized cost of electricity. An integrated system utilizing one active and multiple passive rectifiers with a multiport permanent magnet synchronous generator is a promising alternative for an electromechanical power conversion system. Deployment of the integrated systems in offshore wind energy requires maximum power point tracking (MPPT) capability, which is challenging due to the presence of numerous uncontrolled passive rectifiers. This article shows feasibility of MPPT based on a finding that the active-rectifier $d$ -axis current can control the total system output power. The MPPT capability opens up opportunities for the integrated systems in offshore wind applications.

High Power Density 1 MHz 3 kW 400 V-48 V LLC Converter for Datacenters with improved Core Loss and Termination Loss

Abstract: Power consumption of data centers is increasing rapidly over recent years. Recently, 48V power architecture has attracted more interest in data centers as it offers more efficient architecture. This paper focuses on the implementation of the DC-DC stage of the 3 kW power supply unit. Full-bridge regulated LLC converter is designed with a matrix of two transformers. This paper focuses on the magnetic design of the PCB-based transformer and resonant inductor of the LLC converter. The dimensional effects on core loss are discussed and evaluated. A matrix of two transformers implemented on UI core with rectangular core shape is proposed to minimize the eddy core loss of the transformer core. The termination of the secondary Full-bridge rectifier is also optimized to reduce the conduction loss of the transformer. A low-profile prototype of the designed converter is demonstrated with a peak efficiency of 98% and power density of 700W/in3.

A Single-Stage Dual-Active-Bridge AC–DC Converter Employing Mode Transition Based on Real-Time Calculation

Abstract: In this article, a double degree-of-freedom variable control strategy with fixed frequency is proposed for a single-phase single-stage ac–dc rectifier based on dual active bridges. The proposed modulation strategy can achieve power factor correction without inner current ac current loop. In addition, the two control variables are calculated in real time without using look-up tables, and their combination not only achieves wider zero voltage switching range for switches but also lowers transformer current stress. The mode transition, the soft switching range, and working mode composition are analyzed. Besides, a 1-kW experimental prototype was built to verify the effectiveness of the control strategy.

Second Harmonic Current Reduction for Two-Stage Inverter With DCX- LLC Resonant Converter in Front-End DC–DC Converter: Modeling and Control

Abstract: In a two-stage inverter, the instantaneous output power pulsates at twice the output frequency (2 f o), generating the second harmonic current (SHC), which will propagate into the front-end dc–dc converter. This article aims for suppressing the SHC in the front-end dc–dc converter with dc transformer (DCX)- LLC resonant converter. The small-signal model of the DCX- LLC resonant converter is proposed, and based on which, the unified small-signal model of the preregulator+ LLC converter is built. Then, the basic ideas for reducing the SHC are proposed, including the determination of the filter capacitors in the preregulator+ LLC converter and the control approach. After that, from a perspective of output impedance, the control schemes for reducing the SHC in the front-end preregulator+ LLC converter are proposed. By inserting a notch filter in the voltage loop and/or introducing a virtual impedance in series with the output rectifier of the LLC resonant converter, the output impedance of the preregulator+ LLC converter at 2 f o is increased and, thus, the SHC can be reduced. Finally, a 6-kVA two-stage three-phase inverter with boost+ LLC converter as the front-end dc–dc converter was fabricated and tested. The experimental results are provided to verify the proposed control schemes.

A Family of Dual-Boost Bridgeless Five-Level Rectifiers With Common-Core Inductors

Abstract: In this article, a family of dual-boost bridgeless five-level rectifiers with common-core inductors is proposed, which is composed of two coupled inductors, one bidirectional switch unit, and the dual-boost bridgeless power factor correction (PFC) rectifier. A bidirectional switch unit is embedded in the midpoint between the two capacitors and the bridge arm of the dual-boost bridgeless PFC (DBBL-PFC) to directly generate the five-level waveforms in each line cycle. The proposed topologies have the characteristics of lower voltage/current stresses and low total harmonic distortion. Additionally, the proposed five-level rectifiers employ a pair of common-core coupled inductors at the input side to replace the inherent independent inductors to improve the core utilization and the power density. First, the characteristics of the proposed topologies are analyzed and compared, and one of the topologies is taken as an example to illustrate its operating principle. Second, the modulation strategy with strong topology applicability and control system is designed for the proposed topologies. The advantage of the proposed pulsewidth modulation method is that it only needs to change the pulse distribution of the five-level topology to realize the five-level rectification, and the program debugging is simple. Then, the coupled inductors are designed, compared, and analyzed by the equivalent model in detail. Finally, a rated output of 1 kW/400 V experimental prototype is built, and the experimental results are presented to demonstrate the performance and effectiveness of the proposed topologies.

A Self-Powered S-SSHI and SECE Hybrid Rectifier for PE Energy Harvesters: Analysis and Experiment

Abstract: A self-powered hybrid rectifier based on the association of series synchronized switch harvesting on inductor (S-SSHI) and synchronous electric charge extraction (SECE) is proposed for piezoelectric (PE) energy harvesters, aiming to achieve a good balance between the rectifier peak output power (RPOP) and optimal rectified voltage range (ORVR). The theory and simulation of the hybrid rectifier are presented with a good agreement. The measurements demonstrate that the prototyped hybrid rectifier can output the peak power of 0.28 mW and obtain the maximum end-to-end efficiency of 72.8% under PE open-circuit voltage of 6 V. It can achieve 1.55 times the RPOP of the SECE rectifier and 4.58 times the ORVR of the S-SSHI rectifier. The balance between the two indexes grasped in the hybrid rectifier is better than the others in the test. According to the estimation of FoM, $\text{BW}_{0.9}$ , and $\text{RoI}_{0.9}$ factors, the overall performance of the hybrid rectifier is at the same level compared to state-of-the-art rectifiers. Additionally, the hybrid rectifier is easy to implement with some simple discrete components, which can be an alternative rectifier solution for PE harvesters.

A Lyapunov-Based Model Predictive Control Design With Reduced Sensors for a PUC7 Rectifier

Abstract: This article proposes a Lyapunov-based model predictive control (MPC) design for a dual output multilevel rectifier. The investigated topology, a seven-level packed U-cell (PUC7) converter, is selected based on its high reliability, compactness, and low cost. The proposed controller has the following advantages over the conventional MPC controllers: First, no gain tuning is required; second, easy implementation; and third, reduced number of sensors (the load currents are estimated using the mathematical model of the PUC7 rectifier). Simulation and experimental results are provided to show the high dynamic performance and effectiveness of the Lyapunov-based MPC controller in tracking the output voltage references under grid change and parameters mismatch conditions.

Study and Design of a 2.45-GHz Rectifier Achieving 91% Efficiency at 5-W Input Power

Abstract: To achieve a high-efficiency microwave wireless power transfer system, a high conversion efficiency rectifier is necessary. Brown (1974) designed rectifiers with approximately 3-W input power achieved 90% conversion efficiency for 2.45 GHz, and it maintains the record for maximum conversion efficiency. In this study, to design a high-efficiency and high-power rectifier, we designed a larger semiconductor metal junction area GaAs Schottky diodes possessing very low series resistance and high breakdown voltage. In addition, we built the SPICE model and package model for the diodes. The designed high conversion efficiency rectifier achieved 91% efficiency at 5-W input power for 2.45 GHz.

Efficient Dual-Band Rectifier Using Stepped Impedance Stub Matching Network for Wireless Energy Harvesting

Abstract: This letter presents an efficient dual-band rectifier using stepped impedance stub matching circuit. Theoretical analysis of the dual-band impedance matching circuit comprising a stepped impedance stub is carried out, which plays a key role in designing the resultant dual-band rectifier. The proposed dual-band matching circuit can achieve wide frequency ratio which is analyzed and predicted by simulation. For demonstration, a dual-band rectifier working at 0.915 and 2.45 GHz is fabricated with dimensions of 21.47 mm $\times18.93$ mm. The measured results show that with a $1500~\Omega $ load, the maximum efficiencies of the rectifier reach 74% and 73% at 0.915 and 2.45 GHz, respectively. Due to the simple but efficient structure of the dual-band matching network, the dual-band rectifier in this work exhibits merits of compact size and high efficiency.

Reversible Half Wave Rectifier Based on 2D InSe/GeSe Heterostructure with Near-Broken Band Alignment.

Abstract: 2D van der Waals heterostructures (vdWHs) offer tremendous opportunities in designing multifunctional electronic devices. Due to the ultrathin nature of 2D materials, the gate-induced change in charge density makes amplitude control possible, creating a new programmable unilateral rectifier. The study of 2D vdWHs-based reversible unilateral rectifier is lacking, although it can give rise to a new degree of freedom for modulating the output state. Here, a InSe/GeSe vdWH-FET is constructed as a gate-controllable half wave rectifier. The device exhibits stepless adjustment from forward to backward rectifying performance, leading to multiple operation states of output level. Near-broken band alignment in the InSe/GeSe vdWH-FET is a crucial feature for high-performance reversible rectifier, which is shown to have backward and forward rectification ratio of 1:38 and 963:1, respectively. Being further explored as a new bridge rectifier, the InSe/GeSe device has great potential in future gate-controllable alternating current/direct current convertor. These results indicate that 2D vdWHs with near-broken band alignment can offer a pathway to simplify the commutating circuit and regulating speed circuit.

A Wide-PCE-Dynamic-Range CMOS Cross-Coupled Differential-Drive Rectifier for Ambient RF Energy Harvesting

Abstract: This Brief reports a cross-coupled differential-drive (CCDD) rectifier with a wide dynamic range (DR) in its power conversion efficiency (PCE). Specifically, it features a self-body-biasing technique to reduce the forward Vth, along with the diode-connected MOSFETs to stem the reverse-leakage current while improving the forward current. The merits of our CCDD rectifier are exemplified via two input-capacitor-coupling configurations: shared-capacitor coupling (SCC) and individual-capacitor coupling (ICC) . Fabricated in 0.13- $\mu \text{m}$ CMOS, the SCC-CCDD and ICC-CCDD measure a DR of 13 and 14.5 dB, respectively, for a PCE >40%. Alternatively, the SCC-CCDD exhibits a peak PCE of 83.7% with a sensitivity of −19.2 dBm at 1 V, whereas the ICC-CCDD shows a peak PCE of 80.3% with a sensitivity of −18.7 dBm.

Carrier-based Closed-loop DC-link Voltage Balancing Algorithm for Four Level NPC Converters Based on Redundant Level Modulation

Abstract: Four-level neutral-point-clamped (NPC) multilevel converter topologies have been proposed and actively studied for low/medium voltage applications. As an inherent issue with these topologies, the voltage balancing of dc-link capacitors is challenging, especially when it operates as a single-end inverter/rectifier with high power factors and high modulation indexes. This article proposes a closed-loop voltage balancing algorithm that is effective and simple to implement with regular level-shifted carriers for a four-level NPC converter, e.g., a π-type converter. This approach is based on the redundant level modulation (RLM), which utilizes one additional voltage level in one switching cycle to gain extra controllability of the capacitor voltages without distorting/undermining the fundamental-frequency output voltage. An algorithm based on analytical expressions and logical operations is developed to achieve a dynamic closed-loop voltage balancing with RLM. The proposed method is effective over the full span of linear modulation indexes ( M = 0 ∼ 1.15) and power factors. The proposed algorithm is validated and evaluated in both simulations and experiments.

Effect of probe geometry during measurement of >100 A Ga2O3 vertical rectifiers

Abstract: The high breakdown voltage and low on-state resistance of Schottky rectifiers fabricated on β-Ga2O3 leads to low switching losses, making them attractive for power inverters. One of the main goals is to achieve high forward currents, requiring the fabrication of large area (>1 cm2) devices in order to keep the current density below the threshold for thermally driven failure. A problem encountered during the measurement of these larger area devices is the dependence of current spreading on the probe size, resistance, number, and geometry, which leads to lower currents than expected. We demonstrate how a multiprobe array (6 × 8 mm2) provides a means of mitigating this effect and measure a single sweep forward current up to 135 A on a 1.15 cm2 rectifier fabricated on a vertical Ga2O3 structure. Technology computer-aided design simulations using the floods code, a self-consistent partial differential equation solver, provide a systematic insight into the role of probe placement, size (40–4120 μm), number (1–5), and the sheet resistance of the metal contact on the resultant current-voltage characteristics of the rectifiers.

An Efficient Piezoelectric Energy Harvesting Circuit With Series-SSHI Rectifier and FNOV-MPPT Control Technique

Abstract: This article presents an efficient piezoelectric (PE) energy harvesting (EH) circuit based on the techniques of series synchronized switch harvesting on inductor (Series-SSHI) and maximum power point tracking (MPPT). The MPPT is achieved using the proposed fractional normal-operation voltage (FNOV) method, which is based on the Series-SSHI operating principle. The FNOV method no longer disconnects the PE harvester from the load circuit to measure its open-circuit (OC) voltage. Instead, it measures the peak PE voltage during the normal Series-SSHI operation to enable the continuous EH process. The FNOV-MPPT circuit is implemented based on a variable width hysteresis controller for saving energy. In addition, the prototyped circuit can achieve the figure of merit factor of 2.68 and the maximum MPPT efficiency of 98.1% with the PE OC voltage ranging from 2 to 5 V. The measurements confirm the validity of the proposed FNOV-MPPT solution for the weakly coupled PE harvesters.

2.45 GHz Wi-Fi band operated circularly polarized rectenna for RF energy harvesting in smart city applications

Abstract: This article proposes a single band circularly polarized (CP) rectenna operate at a 2.45 GHz Wi-Fi band, using a hexagonal shape of a microstrip radiator and a voltage doubler rectifier for smart c...

Design Optimization and Electro-Thermal Modeling of an Off-Board Charging System for Electric Bus Applications

Abstract: This paper proposes a co-design optimization procedure of a high-power off-board charger for electric vehicle (EV) applications. The primary purpose is to design a 175 kW SiC DC-charging system with high power density to achieve high efficiency at a wide operating range. For the active part of the DC off-board charger, a three-phase active front end (AFE) rectifier topology is considered in the design optimization and the modelling. The design methodology focuses on the optimal design of the passive filters, accurate electro-thermal modelling of the converter, inductor design, capacitor selection, loss and geometric modelling of the passive filters and control system design. The design optimization of the high-power charging system is performed in MATLAB Simulink using a closed-loop dynamic electro-thermal simulation of the off-board charger. The switching frequency, loss and temperature-dependent efficiency of the charger is investigated in parallel. Through this proposed technique, efficiency greater than 96% is achieved at a switching frequency of 40 kHz, along with a smaller size and lower weight of the system. Moreover, it operates with a current total harmonic distortion (THDi) below 3% and a power factor (PF) above 99% at rated power condition.

A Triband Rectifier Toward Millimeter-Wave Frequencies for Energy Harvesting and Wireless Power-Transfer Applications

Abstract: This letter presents an efficient single-cell triband rectifier matched at millimeter-wave frequencies of 24, 28, and 38 GHz using a novel, compact multiband impedance matching network (IMN). The proposed multiband IMN is scalable and is used to design a miniaturized rectifier at the desired frequencies. The actual impedance of rectifier was measured using through-reflect-line (TRL) calibration for accurate design. A prototype of rectifier was realized on Rogers 5880 substrate. The rectifier is capable of harvesting dc output simultaneously from three different millimeter-wave frequency bands including two 5G communication bands and industrial, scientific and medical (ISM) band at 24 GHz. The maximum simulated efficiencies obtained at 24, 28, and 38 GHz are 44.3%, 42.7%, and 43.6% at an input power of about 15.6 dBm and the measured efficiencies are 44%, 41.3%, and 39.7% at an input power of 17.5 dBm, respectively. This rectifier finds its applications as an energy harvester and wireless power transmitter for self-sustainable low-power batteryless systems.

Minimization of Torque Ripple and Incremental of Power Factor in Switched Reluctance Motor Drive

Abstract: The important drawbacks of the Switched Reluctance Motor (SRM) are torque ripples, acoustic noise, and low power factor. High harmonic current and low power factor arising from the pulsating AC input current and the switching of voltage into the SRM phase winding. It will also lead to high torque ripple and acoustic noise. In the present work, we are using Vienna-type rectifier along with alternate Asymmetric H-Bridge converter for the SRM drive. It provides boosted DC-link voltage and enhancing the quality of the input current. Thus, the power factor (PF) of the SRM drive gets enhanced. This converter configuration also provides lesser Total Harmonic Distortion (THD). Thus, it will address the power quality improvement of the SRM drive. It is even more useful in torque ripple minimization. In this paper, for our analysis, we are considering 8/6 SRM Drive. It is modeled by using the MATLAB/Simulink environment.

Synchronous Push–Pull Class E Rectifiers With Load-Independent Operation for Megahertz Wireless Power Transfer

Abstract: This article presents the analytical modeling of synchronous class E rectifiers with the load-independent operation, which achieves zero-phase-angle input impedance, soft-switching over the entire load range with a constant voltage gain. The optimal design of the synchronous class E rectifier is proposed to realize both zero-voltage-switching turn- on and zero-current-switching turn- off at the expected output power. An $ LCC$ - $S$ compensated MHz-WPT topology, which comprises the push–pull class E inverter and rectifier with the load-independent operation, is proposed to achieve the fully soft-switching and a nearly constant voltage gain over the entire load range. The efficiency improvement of the compensation network is also investigated to provide a design methodology for the proposed topology. A $ 6.78$ -MHz WPT prototype, along with an alternative phase detector using an auxiliary coil to realize phase detection, is built to validate the analytical model and the proposed methodology. The system efficiency reaches $ \text{86.7}\%$ at $ 214$ -W output. The synchronous push–pull class E rectifier maintains soft-switching over the load range, and the rectification efficiency reaches $ 94.6\%$ .