Resonant Bridge Research Articles

Railway vibration – fast physics-based models for the prediction of ground vibration and the identification of track damage

The following applications of machine learning/AI for railway vibration will be discussed: 1. The prediction of the wave propagation from a railway line (completely physics based for surface lines, for tunnel lines (partially) physics-based ML for surface lines). 2. The track behaviour for the emission of train-induced ground vibration (physics based for homogeneous soil, ML for layered soil). 3. Track damage detection and quantification from FRF and moving load response. 4. Bridge damage detection and localisation from modal analysis and moving load response. 5. The use of axle-box acceleration for the identification of track/sub-soil condition and bridge resonances. Prediction calculation of railway vibration usually needs time-consuming finite element, boundary element and wavenumber domain calculations. For a user-friendly prediction software, fast calculations are needed. Several time-consuming detailed calculations should be used to develop simpler and fast models. The dynamic stiffness of isolated or un-isolated railway tracks from detailed calculations with a continuous soil is approximated with the simpler Winkler soil. The vehicle-track resonance (P2 resonance) rules the effect of the mitigation measures, and it can also be used for the on-board monitoring of the track and sub-soil condition. For the identification of track damage such as gaps between sleepers, track slabs and layers, detailed models with a continuous soil have been updated to get the best fit to the measured frequency response functions from hammer tests and the deformation pattern from the moving load response. Whereas the track damage can be locally identified, this is more difficult for bridges where the modal analysis gives mainly global information. The influence lines of the inclination for statically passing vehicles (locomotive, truck, compaction ) have been used to localise bridge damage (stiffness variations). The on-board monitoring of rail bridges needs special conditions (regular trains with special speeds) to excite and measure the bridge resonance.

Research on High-Precision Resonant Capacitance Bridge Based on Multiple Transformers.

The Taiji program is dedicated to the detection of middle and low-frequency gravitational waves, targeting the 0.1 mHz to 1 Hz frequency band. The project requires an acceleration residual sensitivity of 3 × 10-15 ms-2/Hz1/2, which necessitates a capacitance sensing resolution of 1 aF/Hz1/2 for the capacitive sensing system within the specified frequency range. The noise level of the resonant bridge significantly influences the resolution. Addressing the challenges in enhancing transformer performance parameters in existing resonant capacitance bridges and the constraints on improving the characteristics of resonant capacitance bridges, this study introduces a novel approach to reduce bridge thermal noise without optimizing existing parameters. The simulation results demonstrate that this scheme can reduce the noise to 0.7 times the original level and further reduce bridge thermal noise when other parameters affecting noise are optimized. This not only mitigates the demands for other performance parameters but also increases the range of maximum acceptable resonant frequency deviations and reduces its sensitivity to such variations. Experimental validation confirms that the proposed scheme effectively reduces noise by 0.7 times and improves the resolution of capacitance sensing to 0.6 aF/Hz1/2, thereby advancing the Taiji program gravitational wave detection capabilities.

Modeling and Control of an Inductive Power Transmitter Based on Buck–Half Bridge–Resonant Tank

In this paper, a previously proposed converter to be used for inductive wireless power transmission is modeled and a control strategy is proposed. The converter topology combines into a single stage, two buck converters and a half-bridge converter to feed a resonant stage. This simple and symmetrical topology is straightforward to design; only a buck converter and a parallel resonant tank must be specified. It would be desirable for the converter to feed a wide range of loads and be robust under input voltage variations. These objectives can not be attained with a linear model and control. For this reason, in this paper, a nonlinear converter model is derived step by step and controller strategy is developed without relying on system linearization. The proposed controller does not measure the output but only its peak value. This can be conducted because it takes advantage of the square current pulse fed into a resonant tank; it outputs an approximately sinusoidal signal. The control strategy is completed with a scheme to build the required pulse at the input of the resonant tank. The resulting nonlinear controller has a fast closed-loop performance; furthermore, it is robust under parameter uncertainty, and load and input voltage variations. Despite its features, the controller is fairly simple to implement.

Noise and thermal performance of a sub-attofarad capacitance sensor for precision measurements, with applications in gravitational wave detectors.

We describe the design principles, fabrication, and characterization of a precision AC resonant capacitance bridge (RCB) sensor, based on a resonant differential planar printed circuit board transformer with a solid (ungapped) MnZn ferrite core, demonstrating a short-term sensitivity at 293K of 0.225 ± 0.005 aF/√Hz at around 120kHz resonance frequency and 1Hz Fourier measurement frequency. At 120K, the RCB short term noise sensitivity is 0.118 ± 0.005 aF/√Hz. We compare the ungapped configuration to five different RCBs: three with a core gap of 65 μm and two with a core gap of 130 μm. Their average room temperature short term noise sensitivities are 0.30 ± 0.01 and 0.45 ± 0.01 aF/√Hz, while the cryogenic operation of these transformers at 120K resulted in averaged sensitivities of 0.23 ± 0.01 and 0.36 ± 0.01 aF/√Hz, respectively. Multi-hour room temperature runs, with one core of each of the three gap types, proved the stability of their long-term sensitivities of 0.234 ± 0.005, 0.338 ± 0.009, and 0.435 ± 0.010 aF/√Hz for the ungapped (40-h duration) and the 65 and 130 μm (28-h duration) cores, respectively. At 0.1mHz, a critical frequency for space gravitational wave detectors, the respective sensitivities are 0.25 ± 0.02, 0.35 ± 0.02, and 0.53 ± 0.07 aF/√Hz. Measurements with the ungapped transformer configuration for temperatures from 325 to 349K further validate the dependence of the noise model on temperature and permeability. The performance of our RCB with an ungapped core matches the calculated performance value and shows an improvement in signal-to-noise ratio of two or more compared with capacitance bridges developed for similar applications. A further factor of about two noise reductions is achieved by cooling to 120K.

Current Driven Bi-Frequency Resonant Dual Active Bridge Converter for Optimal Battery Charging

Current Driven Bi-Frequency Resonant Dual Active Bridge Converter for Optimal Battery Charging

The effect of electrical parameters of eddy current sensor on metal film thickness measurement performance and the optimization method.

Eddy current sensors have been widely used in the field of micro- and nano-measurements. The detection circuit is a key part of eddy current sensors. In particular, the electrical parameters in the signal conversion circuit have an important effect on the measurement performance. It is necessary to study the effect of the electrical parameters on the measurement performance and propose an optimization method. In this study, a simulation model of the eddy current sensor is established by coupling a magnetic field and a circuit field. The circuits include the LC parallel resonance, the AC bridge, and three combination circuits of the LC resonant and AC bridge. The output voltage variation with the thickness of copper film is calculated, and the effect of the electrical parameters on sensitivity Ki is obtained. In the LC parallel resonant circuit, it' is revealed that K1 is maximum when the parallel capacitance CP is equal to the resonant capacitance C0. An optimization method of adjusting resistance RS in different thickness intervals is proposed. In the AC bridge circuit, it' is revealed that there exists an optimal RS, which makes K2 maximum. In three combination circuits, K3, K4, and K5 are the maximum when the capacitances (C1, C2, and C3) reach the resonant capacitance C0. In addition, the sensitivity of each combination circuit is improved compared with that of the AC bridge. The relevant analysis results are further verified by a series of experiments. According to the calculation results and the experimental analysis, the optimization method for electrical parameters is further proposed.

The Effect of Arc Discharge Plasma Duration to Obtain Graphene Nano Sheet (GNs) From Coconut Shell Charcoal Powder by a Half Bridge Resonance Inverter Circuit as a High Voltage Generator

The Effect of Arc Discharge Plasma Duration to Obtain Graphene Nano Sheet (GNs) From Coconut Shell Charcoal Powder by a Half Bridge Resonance Inverter Circuit as a High Voltage Generator

Enhanced linearity through high-order antisymmetric vibration for MEMS DC power sensor

We present an electric power meter that capitalizes on the interaction of electrothermal strain and mechanical vibration in a micro-electro-mechanical systems (MEMS) beam undergoing the antisymmetric mode of vibration. This is achieved by using a resonant bridge driven with an electrothermal modulation technique. The change in electrical power is monitored through the alteration in the mechanical stiffness of the structure, which is tracked electrostatically. The observed deflection profile of the beam under the influence of electrothermal effects shows that the deflection geometry due to buckling exhibits similar trends as the first symmetric vibrational mode, in contrast to the antisymmetric mode. Therefore, we compare two distinct vibrational modes, converting the compressive thermal stress generated by the input electrical power via Joule heating into a shift in the resonance frequency. By employing antisymmetric vibrational mode, the output of our device is consistently monotonic to the input electrical power, even when the microbeam is experiencing buckling deflections. In addition, the sensing operation based on antisymmetric modes yields only a 1.5% nonlinear error in the response curve, which is ten times lower than that of symmetric modes. The observed deformation shape of the resonator agrees with the results obtained from multi-physics finite simulations. Finally, this approach has the potential to be extended to other frequency-shift-based sensors, allowing for higher linearity.

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%.

Perturbation Observation Method-Based Optimization Seeking Control of Soft-Switching and No Backflow Power for LCL Resonant-Type Dual Active Bridge DC–DC Converters

LCL-type resonant dual active bridge (LCL-DAB) DC-DC converters feature high gain, high power density, and low reactive current. To further improve the efficiency, based on the dual-phase shift (DPS) modulation method, the operating characteristics are firstly derived and the design regions of soft-switching and no backflow power are established, and then a perturbation observation method based optimization seeking control of soft-switching and no backflow power is proposed in this paper. In the starting process, the system firstly tracks the reference voltage according to the relationship between the inner and outer phase shift ratio obtained by the first harmonic approximation. Then, the outer phase shift ratio is perturbed based on the characteristics of soft-switching and backflow power, approaching the target phase shift ratio stepwise, while the inner phase shift ratio is calibrated to hold the output voltage. Both H bridges can operate in soft-switching mode, and on this basis, the backflow power was eliminated to the maximum extent. Finally, the simulation and experimental results verified the feasibility and effectiveness of the proposed method.

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.

Solid-State Transformer Based on Naturally Cell Balanced Series Resonant Converter With Cascaded H-Bridge Cells Switched at Grid Frequency

This paper proposes a closed-loop control architecture for a three-stage (MV, isolated DC/DC, LV) Solid State Transformer (SST) system and a modulation technique for the MV stage that shows better performance over existing solutions in terms of control simplicity, semiconductor loss, and cost. A simple and effective closed-loop control architecture is proposed for the entire SST system using the natural cell balancing ability of the Series Resonant Dual Active Bridge (SRDAB) converters in the DC/DC stage. In order to reduce semiconductor losses and cost, Si IGBT and SiC MOSFET devices are introduced properly in the MV stage of the SST power architecture, and the proposed modulation technique switches these devices appropriately according to their merits. The proposed modulation scheme ensures more than 50% semiconductor loss reduction in the MV stage. A circulating logic is proposed to achieve equal power sharing among cells in the MV stage and associated components. Detailed dynamic modeling, closed-loop control architecture, and modulation scheme are discussed in this paper. The proposed control technique and modulation scheme are verified experimentally in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{600}~V/100~V, \text{5}~kW$</tex-math></inline-formula> SST system.

Trajectory-Switching-Modulation-Based Fast Power Transient Control Strategy for a Bidirectional Hybrid Modular DC Transformer

The hybrid modular DC transformer (HMDCT) combining the series resonant dual active bridge (SR-DAB) and phase-shift dual active bridge (PS-DAB) has the advantages of high efficiency and bidirectional power regulation. However, due to the unregulated SR-DAB resonant tank inertia and limited PS-DAB output power, the dynamic response of HMDCT is slower than the pure PS-DAB based DC transformer, which could lead to a larger output overshoot. To address the problems, first, a novel trajectory-switching-modulation (TSM) method is proposed to control the SR-DAB resonant tank to track the desired state-trajectory rapidly by using SR-DAB switch-states. Compared with the conventional LLC trajectory control, TSM is more suitable for the SR-DAB in the bidirectional HMDCT because TSM is available under bidirectional power flow without changing the topology or increasing magnetizing losses. Then, a TSM based fast power transients control strategy is proposed to improve the bidirectional HMDCT dynamic performance by controlling the PS-DAB and SR-DAB simultaneously. Besides, PS-DAB current stress can also be reduced during the load transients. Experimental results show that the proposed strategy has better dynamic performance than the classic proportional-integral feedforward based strategy.

A Resonant Gas Sensor With Functional Composite Stress Generator

A bridge resonator consisting of a micro beam and a functional composite membrane is proposed in this work for gas detection. The gas molecules adsorbed onto the membrane will generate an axis compressive stress on the micro clamped-clamped beam to decrease the bending stiffness by expanding the designed silicon slits structure, as well as increase the effective mass of the resonator. The resonant frequency shift of the proposed sensor is thus greater than those based only on mass change or stiffness change, showing a higher gas sensitivity. The bridge structure of the sensor was successfully fabricated for experimental study. To explore the response of the proposed sensor to humidity, various relative humidity produced in a designed measuring system are applied to a test chamber. The evaluation results showed that the resonant frequency of the sensor decreases with the increase of humidity. Significantly, there is an apparent linear relationship between resonant frequency and relative humidity of 28 Hz per 1% relative humidity with negligible deviations and the linear goodness of fit can reach 99.65%, when the relative humidity is lower than 12%. The results indicate a high sensing resolution of 0.5% and high repeatability. Besides, the detection of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S gas with a low concentration of 5 ppm is demonstrated by this proposed resonant gas sensor. With the proper selection of the functional membrane, an array of sensors is potential to be applied in detecting various volatile gas components in human breath and in atmosphere.

A wide zero-voltage-switching range with low reactive power modulation strategy for LCL resonant three-phase dual active bridge DC–DC converter in renewable energy generations

LCL resonant three-phase dual active bridge (LCL-TPDAB) dc–dc converter is progressively used in renewable energy systems due to the advantages of low circulating reactive power and wide voltage regulation. Conventional dual-phase-shift (DPS) modulation can effectively reduce the circulating reactive power of the converter, but it cannot achieve zero-voltage-switching (ZVS) of all switches, which increases switching losses and generates electromagnetic interference. To solve the above problems, an optimized modulation strategy based on phase-shift plus duty cycle (PSPDC) control is proposed in this paper. Firstly, the mathematical model of the LCL-TPDAB converter with the PSPDC modulation is established by harmonic analysis. Then, the relationship between the ZVS boundaries and the control variables is determined by analyzing the soft-switching characteristics. In order to accurately describe the ZVS boundaries, the impact of switch junction capacitance is considered in the analysis. Further, an optimized modulation strategy is proposed, which can achieve ZVS for all switches and low reactive power in the whole operating range. Furthermore, the offline particle swarm optimization (PSO) algorithm is introduced to acquire the optimal control variables in the operation of the converter. Finally, a 1.5 kW experimental prototype is applied to verify the effectiveness and excellence of the proposed optimized modulation strategy, where the efficiencies are improved in the whole operating range.

Multifunctional Resonance Bridge-Mediated Dynamic Modulation of Perovskite Films For Enhanced Intrinsic Stability of Photovoltaics.

The improving intrinsic stability, determining the life span of devices, is a challenging task in the industrialization of inverted perovskite solar cells. The most important prerequisite for boosting intrinsic stability is high-quality perovskite films deposition. Here, a molecule, N-(2-pyridyl)pivalamide (NPP) is utilized, as a multifunctional resonance bridge between poly(triarylamine) (PTAA) and perovskite film to regulate the perovskite film quality and promote hole extraction for enhancing the device intrinsic stability. The pyridine groups in NPP couple with the phenyl groups in PTAA through π-π stacking to improve hole extraction capacities and minimize interfacial charge recombination, and the resonance linkages (NCO) in NPP dynamically modulate the perovskite buried defects through strong PbO bonds based on the fast self-adaptive tautomerization between resonance forms (NCO and N+ CO- ). Because of the combined effect of the reduction defect density and improved energy level in the perovskite buried interfaces as well as the optimized crystal orientation in perovskite film enabled by the NPP substrate, the devices based on NPP-grown perovskite films show an efficiency approaching 20% with negligible hysteresis. More impressively, the unencapsulated device displays start-of-the-art intrinsic photostability, operating under continuous 1-sun illumination for 2373 h at 65°C without loss of PCE.

Dynamic Analysis of a Coupled System of High-Speed Maglev Train and a Flexible Long-Span Continuous Rigid Frame Bridge

The dynamic characteristics, deformation and installation accuracy of the bridge structure will have a greater impact on the response of maglev system. This study performs the dynamic analysis of a flexible long-span continuous rigid frame bridge induced by high-speed maglev train. To achieve this, the spatial coupling analysis model is first established. Then, the influence of track irregularities and speed on the maglev system is analyzed. In addition, the mechanism of vertical resonance of the bridge and vehicle under the action of harmonic loads at low speed is also studied by a semi-analytical approach. The results show that the influence of the long-span bridge deformation on car-body vertical acceleration is greater than that of track irregularity. The resonance exists between train and the long-span bridge at low speed. When the frequency of the harmonic loads is consistent with the basic frequency of the bridge, it will cause the bridge resonance. The resonant speed range of the rigid car-body is 20–40[Formula: see text]km/h. During bridge design, it shall be avoided that the basic frequency of the bridge is consistent with that of the vehicle.

A multi-sensing scheme based on nonlinear coupled micromachined resonators

A new multi-sensing scheme via nonlinear weakly coupled resonators is introduced in this paper, which can simultaneously detect two different physical stimuli by monitoring the dynamic response around the first two lowest modes. The system consists of a mechanically coupled bridge resonator and cantilever resonator. The eigenvalue problem is solved to identify the right geometry for the resonators to optimize their resonance frequencies based on mode localization in order to provide outstanding sensitivity. A nonlinear equivalent model is developed using the Euler–Bernoulli beam theory while accounting for the geometric and electrostatic nonlinearities. The sensor's dynamics are explored using a reduced-order model based on two-mode Galerkin discretization, which reveals the richness of the response. To demonstrate the proposed sensing scheme, the dynamic response of the weakly coupled resonator is investigated by tuning the stiffness and mass of the bridge and cantilever resonators, respectively. With its simple and scalable design, the proposed system shows great potential for intelligent multi-sensing detection in many applications.

Coupled Thin Film Hydrogenated Amorphous Silicon Microresonator Arrays

Mechanically coupled resonators can potentially improve the sensing capabilities of MEMS resonators. This work presents novel weakly and moderately coupled MEMS bridge resonators with up to four degrees-of-freedom (DOF), with thin-film hydrogenated amorphous silicon thin films as structural layers fabricated on glass substrates by surface micromachining at temperatures no greater than 175 °C. The electrostatically actuated coupled resonators exhibited flexural fundamental resonance frequencies near 1 MHz. Coupled resonance modes were simulated by Finite Element Method and characterized using optical and electrical sensing. Laser Doppler vibrometry was used to scan the coupled mode shapes and confirm resonance mode attribution. Coupled resonators with 4-DOF exhibited motional resistances ~25 times lower than single resonators (1-DOF) actuated with identical voltages. Common (in-phase) and independent (out-of-phase) actuation of the coupled resonators was implemented, resulting in distinct dynamic behaviors of the coupled array. The fabrication process presented in this work is easily scalable to higher degrees-of-freedom and to large-area substrates, which makes it a good fit for large-scale sensing applications. [2022-0161]

Power Factor Corrector Control Strategies of a Bidirectional Wireless Battery Charger With an Unfolding Active Rectifier

In this article, two power factor corrector (PFC) control strategies for a bidirectional inductive power transfer (IPT) system are proposed. These control strategies are presented for a novel power circuit without input and output interfaces for a wireless electric vehicle battery charger application. This compact topology comprises: unfolding rectifier, primary resonant bridge, and secondary-side active rectification. Two PFC controls are described in detail: a primary-side PFC control, performed in the primary resonant bridge; and a secondary-side PFC control, implemented in the secondary-side active rectification stage. Both strategies are based on a duty-cycle control operating close to the resonance frequency, integrating different functionalities, i.e., PFC, current shaping (CS), and power control on a single control strategy. We analyze each control strategy, evaluating them for different operating points of the charging process. The performance of the wireless charger applying both control strategies is evaluated in terms of power losses, power factor, harmonic distortion, and bifurcation. Additionally, the theoretical results are validated using a GaN-based experimental prototype. The presented analysis and experimental results clearly identify the advantages and limitations of each control strategy leaving no doubt about their usefulness for the future IPT systems.