Phase Shift Mode Research Articles

Analysis, Modeling and Cascade Operation of Wind Energy Fed Dual Active Bridge Converter Operating in Extended Phase Shift and Single Phase Shift Modes: A Comparative Study

In this work, cascade control of wind energy conversion System (WECS) fed Dual Active Bridge (DAB) converter is presented. The Permanent Magnet Synchronous Generator (PMSG) is used to feed the DAB. The real time wind speed data of Muppandal, Tamilnadu, India is fed to the PMSG. The DAB is operated in Extended Phase Shift (EPS) and Single-Phase Shift (SPS) control modes. An outer voltage controller in cascade with an inner current controller is used for closed loop operation of the DAB. The proposed controller is tested for small wind speed variations (13 m/s to 10 m/s) with a step load change and wide changes in wind speed (13 m/s to 8 m/s) accompanied with a step load change. DAB controls the power flow from the WECS to resistive load and its power carrying capability when controlled via the proposed controller is exhibited in the presented work. The proposed configuration controlled via the new cascade EPS controller draws lower power (100 Watts) and offers superior efficiency (85.10%) when compared with cascade SPS controlled microgrid configuration. The cascade controller is tested in MATLAB/Simulink environment and a prototype of DAB is developed in lab for which the cascade controller is tested through the TI-Piccolo-F280049 microcontroller.

A two-phase unwrapping three-dimensional measurement method based on phase shift coding

The periodic misalignment of the wrapping phase and fringe order based on the phase-shift + coding method is known to occur easily, leading to jump errors in absolute phase recovery. This paper proposes a two-phase unwrapping method based on shifting-phase coding. This approach encodes the fringe order information and the wrapping phase into the four-step phase shift mode. It generates four composite fringe patterns to directly resolve the wrapping phase and fringe order, thus improving the measurement speed by reducing the number of fringe projections. The interleaved wrapping phases are then constructed by a sequence that changes the initial wrapping phase. The two-phase unwrapping becomes the absolute phase, so the phase error is avoided and the measurement accuracy is improved. The proposed strategy’s effectiveness is proved by the comparison experiments of different methods. Similarly, the suggested method’s reliability is verified by the measurement experiments of several discontinuous objects.

K‐band CMOS low‐noise amplifier with 180° phase shift function using cascode structure

AbstractIn this study, a K‐band CMOS low‐noise amplifier (LNA) with a 180° phase shift function is presented to reduce the chip area of the beamforming system. The proposed LNA is composed of three stages, and the last stage is designed with a differential cascode structure for 180° phase shift function. The 180° phase shift function was implemented by dividing one cascode transistor into two transistors. As a result, it is possible to equip the 180° phase shift function without an additional chip area. The LNA was designed with a 65‐nm CMOS process to verify the feasibility of the proposed technique. The core size was 0.66 × 0.41 mm2. The measured phase difference between 0° and 180° phase shift modes was approximately 178° in the operating frequency of 22.0 GHz. The measured noise figure and gain were 3.8 and 12.7 dB, respectively.

Design of K-Band Power Amplifier with 180-Degree Phase- Shift Function Using Low-Power CMOS Process

In this study, a K-band complementary metal oxide semiconductor (CMOS) power amplifier was designed using a low-power (LP) process to improve the integration of the beamforming system. In order to reduce the overall system size, a 180° phase-shift function was mounted. It was designed in a four-stage structure to secure sufficient gain. In addition, we propose a way to secure wideband characteristics by utilizing the gains of each of the four stages. The power amplifier was designed with a 40-nm LP CMOS process to verify the feasibility of the proposed technique. The measured P1dB for 0° and 180° phase-shift modes were 15.25 dBm and 14.30 dBm, respectively, at the operating frequency of 25.0 GHz. The measured phase difference between the two modes was 217° at the 25.0 GHz.

Asymmetric Bidirectional Capacitive Power Transfer Method With Push–Pull Full-Bridge Hybrid Topology

Bidirectional capacitive power transfer technology makes it possible for energy sharing among multiple electronic devices. This article proposes an asymmetrical bidirectional power conversion topology to satisfy different input and output characteristics’ requirements and increase load variation tolerance. A π–T ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLC</i> – <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> ) resonant topology is designed for this bidirectional conversion mode with constant output voltage characteristics in both directions. A hybrid power flow regulation strategy is proposed by integrating multiple zero-voltage switching soft-switching operating points switching and phase-shifted mode. This method overcomes the problem of mixing two different type topologies (push–pull and full bridge) with two different power regulation modes (switch soft-switching operating points and phase shift), which provide a way to make two different chargers compatible. Simulation and experimental results verified the proposed method.

Phase-shift mode of the East Asian trough from December to February: Characteristic and possible mechanisms

The East Asian trough (EAT) is an important member of the East Asian winter monsoon system, profoundly influencing the local climate in winter. In this study, we report the phase-shift mode of the monthly EAT variations from December to February based on the extended empirical orthogonal function (EEOF) method. Associated with the phase-shift mode are the noticeable opposite air temperature anomalies over East Asia between December and February, consistent with the recently reported warm early winter and cold late winter (or vice versa). Possible mechanism analysis indicates that the EAT phase-shift mode is closely linked with the anomalous North Atlantic Oscillation (NAO). By exciting a zonal Rossby wave train in December, an anomalous NAO could lead to significantly simultaneous changes in the EAT. However, in January, the NAO-excited Rossby wave train could hardly reach East Asia and has a weak influence on the EAT. In contrast, anomalous NAO in January can significantly influence Arctic Sea ice, causing significant sea ice anomalies over the Barents-Kara (BK) Sea. The BK Sea ice anomalies can persist to the following February, which further excites a Rossby wave train propagating to East Asia, leading to the opposite anomalous EAT in February relative to that in December. Therefore, through the exciting Rossby wave train in December and its resultant BK Sea ice anomalies in February, the NAO contributes to the phase shift of the anomalous EAT from December to February.

A reconfigurable balanced loaded‐line phase shifter based on slot line

A reconfigurable balanced phase shifter is designed in this paper, which can achieve stable differential mode (DM) phase shift and high common mode (CM) suppression. The proposed balanced phase shifter is mainly composed of micro strip/slot line transition structure and π-shape slot line. The U-shaped micro strip line and the stepped impedance slot line are employed to form the differential input and output ports, which can make the DM response and the CM one are independent. By switching the PIN diode on or off, a stable 180° DM phase shift difference is achieved between two states. In order to verify the design, a 180° balanced phase shifter with a central frequency of 4.7 GHz was simulated and fabricated. DM insertion loss of the design is 1.1 dB, DM phase deviation range is ±5°, 10 dB DM impedance matching fractional bandwidth is 45%, and phase fractional deviation bandwidth is 42%. Meanwhile, the CM rejection can reach about 35 dB. The simulation and measurement are in good agreement with the theory.

Research and Design of LC Series Resonant Wireless Power Transfer System with Modulation Control Method for Supercapacitor Charging in Linear Motion Systems

With the hot topic of “Carbon Neutrality”, energy efficiency and saving practices such as reducing fuel consumption, vigorously advocating new energy power and modern rail are now becoming the main research topics of energy conversion technologies. Supercapacitors, with their ability of higher power density, fast charging, and instantaneous high current output, have become an indispensable energy storage element in modern traction systems for modern rail. This proposal introduced wireless power transfer technologies by using LC series resonant technology for charging the supercapacitors. To match the voltage and current level of the supercapacitor, a four-switch buck-boost converter was applied on the secondary side of the load-matching converter. To regulate the wireless transfer power and charging power of the supercapacitor, the active modulation control method was introduced on both the primary and secondary sides of the transfer system. On the primary side, the power is controlled by controlling the current in resonant inductance through the phase shift control method, while on the secondary side, the charging power is controlled by regulating the input voltage of the four-switch buck-boost converter followed by inductance current control. The theoretical analysis under phase shift mode for the primary side and pulse width modulation for a four-switch buck-boost converter with a supercapacitor load (voltage source) were proposed in detail, and the state-space model of the load matching converter was established for controller design to obtain precise voltage and current control. Both open loop and closed loop simulation models were built in the MATLAB/SIMULINK environment, and simulations were carried out to evaluate the system characteristics and control efficiency. The experimental platform was established based on a dsPIC33FJ64GS606 digital controller. Experiments were carried out, and the results successfully verified the effectiveness of the system.

Ultralow Emittance Thermal Radiation Barrier Achieved by a High-Contrast Grating Coating

Thermal radiative emission in vacuum is minimized using metal-backed flexible “space blankets” that have a theoretical minimum infrared emittance of 0.03. However, their presence under oxygenated and degradation-prone environments rapidly increases emittance due to metal oxidation, surface pitting, and implantation of contaminants. A monolithic dielectric coating composed of microscale periodic metasurface gratings on multilayers and metal thin film can achieve sub-1% total emittance. The minimum emittance can be tailored to any temperature-function blackbody emission, so long as the selected dielectric coating materials have near-zero absorption. Using computational optimization and theoretical understanding of high-contrast grating phase-shift mode conditions, we identified characteristic at-wavelength germanium gratings and a near-quarter-wave layer above a low-refractive-index infrared-transparent Fabry–Pérot multilayer interference cavity. This dual mechanism can achieve a room-temperature total emittance of 0.0085, paving a new theoretical minimum multilayer insulation effective conductance. As multilayer insulation, this coating offers total effective emittance of 0.0032 per pair of optimally mismatched grating surfaces. This ultrahigh reflection coating design can also be relevant in thermal management of refrigeration and electronic components.

Terabyte capacity-enabled (10 x 400 Gbps) Is-OWC system for long-haul communication by incorporating dual polarization quadrature phase shift key and mode division multiplexing scheme

Inter-satellite optical wireless communication (Is-OWC) links can become promising solutions to realize the next-generation high-speed communication services. The operation of Global Navigation Satellite Systems can be improved with the use of Is-OWC links through ranging and communication services. However, the key challenge in Inter-satellite link (ISL) is its effective range which is limited due to pointing errors. In this work, we propose to develop a high-capacity and long-reach Is-OWC link by incorporating hybrid mode division multiplexing (MDM) and wavelength division multiplexing (WDM) schemes to transmit ten independent channels over 40000kms Is-OWC link. Each channel is capable of carrying 400Gbps data which is encoded by the dual polarization quadrature phase shift key technique with required signal to noise ratio (SNR) and received power. The proposed Is-OWC link satisfies the enhanced communication within Geostationary Earth Orbit (GEO) and Low Earth Orbit (LEO) satellites. The proposed Is-OWC is further evaluated under the impact of space turbulences, particularly transmitter and receiver pointing errors. The result reported that the proposed Is-OWC link can transmit 4Tbps data over 16000kms with the transmitter pointing error of 2μrad and receiver pointing error of 1μrad.

Review of integrated magneto-optical isolators with rare-earth iron garnets for polarization diverse and magnet-free isolation in silicon photonics [Invited

Passive optical isolators are needed in silicon photonics but unavailable due to challenges in rare-earth iron garnet processing and integration. Material challenges include incompatibility with silicon and high annealing temperatures, and design challenges include a need for polarization diversity and a preference for no external magnetic bias. These challenges have restricted optical isolation to discrete modules that require physical pick and place of bulk garnet pieces. This review presents developments in the processing of magneto-optical garnets on Si and the enhancement of their Faraday rotation that enables small footprint isolators on silicon waveguide structures. For example, seedlayers and/or new garnet compositions have enabled monolithic Si integration, and in some cases, hybrid integration of garnet-on-garnet or transfer-printed garnet nanosheets enable reduced on-chip thermal processing. Integrated isolators that utilize non-reciprocal phase shift (NRPS) or non-reciprocal mode conversion (NRMC) have been demonstrated to have isolation ratios up to 30 dB, insertion loss as low as 9 dB, polarization diversity and magnet-free operation in the desired telecommunication wavelengths. The advances in materials, processing techniques, and isolator designs shown here will pave the way for on-chip isolators and novel multi-lane photonic architectures.

Polymer Stabilization of Uniform Lying Helix Texture in a Bimesogen-Doped Cholesteric Liquid Crystal for Frequency-Modulated Electro-Optic Responses.

A polymer network (PN) can sustain the uniform lying helix (ULH) texture in a binary cholesteric liquid crystal (LC) comprising a calamitic LC and a bimesogenic LC dimer. Upon copolymerization of a bifunctional monomer with a trifunctional monomer at a concentration of 5 wt% to create the desired polymer network structure, the PN-ULH was obtained with high stability and recoverability even when cycles of helical unwinding-to-rewinding processes were induced after the electrical or thermal treatment. Utilizing dielectric spectroscopy, the flexoelectric-polarization-dominated dielectric relaxation in the PN-ULH state was characterized to determine two frequency regions, f < fflexo and f > fdi, with pronounced and suppressed flexoelectric effect, respectively. It is demonstrated that the cell in the PN-ULH state can operate in the light-intensity modulation mode by the flexoelectric and dielectric effects at f < fflexo and phase-shift mode by the dielectric effect at f > fdi. Moreover, varying the voltage frequency from f < fflexo to f > fdi results in a frequency dispersion of transmittance analogous to that of flexoelectric-polarization-dominated dielectric relaxation. The unique combination of the bimesogen-doped cholesteric LC with a stable and recoverable PN-ULH texture is thus promising for developing a frequency-modulated electro-optic device.

Evaluation of Arc Stability in Double-Wire DP-GMAW of Aluminum Alloy Based on U-I Graph

Abstract Severe arc interference in double-wire double pulsed gas metal arc welding (DP-GMAW) can affect the stability of the welding process. In this study, voltage and current waveforms during double-wire DP-GMAW of aluminum (Al) alloy in the 0 deg and 180 deg phase shift modes were recorded. The relationship between arc voltage and welding current was investigated through the output voltage-current (U-I) graph. In addition, arc load characteristics and variation of voltage and current during the DP switching process were analyzed. The arc behavior was recorded throughout the welding process using a high-speed photography system, and the relationship between the U-I graph characteristics and arc stability was further investigated. The experimental results demonstrate that the arc is more stable in the 180 deg phase shift mode. In both phases, the leading arc impedance is more capacitive, and the trailing arc impedance is more resistive.

Interleaved Single-Stage LLC Converter Design Utilizing Half- and Full-Bridge Configurations for Wide Voltage Transfer Ratio Applications

Automotive on-board dc-dc converters are required to operate over a wide input and output voltage range depending on the state of charge of the input and the output battery. Conventionally, the unidirectional power transfer between these batteries is enabled by a two-stage converter concept. A first-stage nonisolated dc-dc converter regulates the input voltage of the galvanically isolated second-stage dc-dc converter such that the second-stage converter operates in its optimum operating point. This article presents a single-stage interleaved LLC resonant converter of 3.6 kW for this purpose. While LLC converters are usually not suitable to cover such a wide voltage range (the input voltage between 240 and 420 V and the output voltage between 8 and 16 V), this LLC converter is operated in a full-bridge mode for large gains and in a half-bridge mode for low gains. For intermediate gains and loads, the LLC employs the phase-shift mode. To operate the interleaved LLCs at equal switching frequencies enabling output current ripple cancellation to reduce the output capacitor, again, the phase-shift mode is utilized to balance the power transfer during the full-bridge mode while the asymmetrical duty-cycle mode is proposed for power balancing during the half-bridge mode. This article analyzes the converter design for these modes of operation and provides a comprehensive design procedure allowing the designer to simultaneously analyze all stress values for various resonant tank designs. A 3.6-kW prototype employing Si superjunction MOSFETs achieves a power density of 2.1 kW/L. The maximum efficiency reaches 96.5%, while for most operating points, it is kept well above 90%. The experimental measurement results validate the analysis and show that phase-shift operation and asymmetrical duty-cycle modulation can be utilized for power balancing for full-bridge and half-bridge configurations, respectively, such that a much smaller output capacitor can be employed.

Preliminary study of phase-shifting strobo-stereoscopy for cutting tool monitoring

Monitoring cutting tool quality in the machining process is essential to the success of part manufacturing. To directly monitor the information of cutting tools under the drilling or milling operations, this paper presents a novel 3D imaging technique to enable direct cutting tool geometry measurement. This method combines stroboscopy and stereoscopy, this strobo-stereoscopy, which synchronizes the stroboscopic illumination system with the spindle control system and enables in-situ reconstructing 3D images of cutting tools. For the phase-locked mode, this technique can lock the image of the cutting tool while in motion. On the other hand, for the phase-shifting mode, all facets around the cutting tool will be scanned by shifting the phase of the light signals while collecting dimensional target information. Experimental studies of phase-locked and phase-shifting modes for monitoring an end mill tool and a wood rolling pin were presented. The directly measured maps and whole 3D images on the target tools verify the capability of the geometry identification of the proposed strobo-stereoscopic imaging technology. Lastly, the potential applications of the proposed technology were discussed.

Contrast simulation in the phase shift dynamic magnetic force microscopy depending on the MFM probe geometry and materials

The gradient of the magnetic force caused by the interaction of various shapes magnetic nanoprobes with magnetic materials has been simulated. Because the force gradient is proportional to the phase shift in probe oscillations the data obtained allow us to compare the contrast of dynamic magnetic force microscopy images for probes with various shapes. A comparison of standard pyramidal probes and probes with cylinder-shaped nanowiskers with different aspect ratios has been carried out. The probes with optimal parameters such as the shape, the thickness and type of the magnetic coating giving the maximum phase shift and as a result giving the best quality visualization of magnetic fields on the sample surface in the phase shift mode have been selected.

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Four‐kilowatt homogeneous microwave heating system using a power‐controlled phase‐shifting mode for improved heating uniformity

For homogeneous microwave heating in a microwave cavity with multiple 2.45 GHz microwave generators, power-controlled phase-shifting mode is proposed in this Letter. The proposed microwave heating system consists of a multimode microwave cavity in which dielectric materials are placed to be heated, four phase-shifting WR-340 waveguides for different phase excitation, four 1 kW magnetrons that produce microwave power at 2.45 GHz, and a power supply with a system controller for the magnetron output power controls. Using the proposed power-controlled phase-shifting mode, uniform heating distribution is achieved by reducing the hot and cold spots in the microwave cavity. The proposed experiments demonstrated that in comparison to a conventional mode with simultaneous multiple inputs, the proposed mode can achieve an improved heating uniformity of 64.4.

Integrated Control Strategy for Inductive Power Transfer Systems with Primary-Side LCC Network for Load-Average Efficiency Improvement

An inductive power transfer (IPT) system has lower peak efficiency and significantly lower load-average efficiency over the entire range of output power than typical power conversion systems because it transmits power wirelessly through magnetically coupled coils. In order to improve the load-average efficiency of the IPT system, this paper proposes an integrated control strategy consisting of full-bridge, phase-shift, and half-bridge control modes. The coupling coefficient and output power conditions for each control mode are theoretically analyzed, and the proposed control algorithm is established. In order to verify the analysis results, a 3.3 kW IPT system prototype is constructed, and it is experimentally verified that the load-average efficiency is improved by up to 3.75% with respect to the output power when using the proposed control scheme. In addition, the proposed control has the additional advantage that it can be directly applied to the existing IPT system without changing or adding hardware.

Review and comparative analysis of dual active bridge isolated DC to DC converter with different control techniques

Bidirectional energy transfer capability is the central part of a lot of modern power conversion systems. Preferably, for reduction of size, weight and cost, these systems use a single high efficiency power electronic conversion system. A dual active bridge converter having two DC-AC converters connected back to back through an AC inductor/transformer is a common topology used for obtaining high efficiency bidirectional power conversion. Some characteristic features of the DAB converter topology are bidirectional power flow capability, inherent soft switching, high power density, high efficiency, galvanic isolation and low number of passive components. In this paper, circuit operation, design, and comparison of efficiency, switch stress, and closed-loop operation of a dual active bridge (DAB) converter for step load variations are discussed and simulated, dual active bridge converter is simulated with closed-loop controller and efficiency is obtained in simulation. Also, switch stress is calculated in simulations. Various control strategies like single phase shift, dual phase shift, extended phase shift and triple phase shift are compared and respective waveforms are shown. Dual active bridge is simulated in MATLAB in single phase shift, extended phase shift, dual phase shift and triple phase shift modes and waveforms are obtained via simulations.