Resonant Bridge Research Articles

Dynamic Modelling of The Series Resonant Converter Operating in Discontinous Conduction Mode And its Application in Space

The Series Resonant Full Bridge operating in Discontinuous Conduction Mode (DCM) at fixed frequency, SRFB-DCM, is an interesting topology to provide isolation in the interface to main buses while having high efficiency thanks to Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS). As this converter cannot be regulated, usually, it is more interesting for regulated buses or in case there is post-regulation. This converter finds application in Power Processing Units for Electrical Propulsion and in any secondary high power front-end converter.Despite its simple design without regulation, in general, the dynamic behaviour of resonant converters is difficult to predict. A model is necessary to predict compatibility with input and output interfaces (stability, output impedance, start-up in-rush,…), avoiding late discovery of oscillations, for example.This paper presents a method to obtain the theoretical dynamic model of the SRFB-DCM with fixed frequency and duty cycle which seems easier to understand but surprisingly not treated in literature. Results are contrasted with simulations.

Comparative studies of global and targeted control of walkway bridge resonant frequencies

In this paper, three controllers are investigated for active vibration control of a pedestrian walkway structure. They comprise direct velocity feedback, observer-based and independent modal space controllers that are implemented in single-input single-output (SISO), multi-SISO and multiple-input multiple-output (MIMO) configurations. The objective of the SISO controller schemes is to compare vibration mitigation performances arising from global control versus selective control of structural resonant frequencies in a given frequency bandwidth. The objectives set out for the multi-SISO and MIMO controllers are to realize global control within the same frequency bandwidth considered in the SISO studies. A novel aspect of these latter studies is the independent control of selected resonant frequencies at different locations on the structure with the aim of imposing global control. Vibration mitigation performances are evaluated using frequency response function measurements and uncontrolled and controlled responses to a synthesized walking excitation force. In the SISO studies, selective control of specific resonant frequencies has a slight degradation in the global vibration mitigation performance, although it reflects better performance around the target frequencies. For the multi-SISO and MIMO controller studies, the selective control of the two lowest and dominant frequencies of the structure at two different locations still offers comparative vibration mitigation performances with the controllers considered as global in the sense that they target both structural frequencies at both locations. Attenuations of between 10 and 35 dB are achieved.

Size-dependent role of gold in g-C3N4/BiOBr/Au system for photocatalytic CO2 reduction and dye degradation

Surface plasmon resonance (SPR) and Z-scheme bridge are the most important roles of noble metal nanoparticles for photocatalysis. In this study, the size-dependent role of gold (Au) in Au/g-C3N4/BiOBr system was studied for photocatalytic CO2 reduction and dye degradation. The results revealed that big Au nanoparticles mainly displayed Z-scheme bridge role, and g-C3N4/BiOBr/Au-B showed higher photocatalytic activity than g-C3N4/BiOBr under 380nm monochromatic light irradiation. Small Au nanoparticles mainly displayed SPR role, and g-C3N4/BiOBr/Au-S showed higher photocatalytic activity than g-C3N4/BiOBr under 550nm monochromatic light irradiation. The size-dependent role of Au nanoparticles for photocatalytic system should be due to the SPR effect of small Au nanoparticles and electron transfer center of big Au nanoparticles. This finding can guide us to prepare high photocatalytic activity noble metal loaded photocatalysts.

A Partially Wettable Micromechanical Resonator for Chemical- and Biosensing in Solution

The presented micromechanical bridge resonator exhibits a comparatively small mass-to-quality factor ratio if operated in solution and is thus adequate for in situ chemical- and biosensing. The mandatory reduction of viscous losses was achieved by partial wetting – that is the significant reduction of the liquid-resonator interfacial area. Featuring a selective excitation of the basic torsional mode using Lorentz forces, the presented resonator could be incorporated as a frequency determining element into an oscillator circuit. Thus a time resolution in the millisecond range was obtained, while mass changes of a few femtogram can be monitored in solution. As proof of concept the adsorption of silica nanobeads and plant viruses was investigated.

A Dual-Active Bridge Topology With a Tuned <italic>CLC</italic> Network

This paper proposes a resonant dual-active bridge (DAB) converter, which uses a tuned capacitor–inductor–capacitor network. In comparison to the conventional DABs, the proposed topology significantly reduces the bridge currents, lowering both conduction and switching losses and improving the bridge power factors. A mathematical model, which predicts the behavior of the proposed system, is presented to show that both the magnitude and direction of the power flow can be controlled through either relative phase angle or pulse width modulation of voltages produced by the bridges. The viability of the proposed concept is verified through simulation. Experimental results of a 4- kW prototype converter, which has an efficiency of 95% at rated power, are also presented with discussions to demonstrate the improved performance of this topology.

Power Factor Corrected Single Stage AC-DC Full Bridge Resonant Converter

Power Factor Corrected Single Stage AC-DC Full Bridge Resonant Converter

Geometrically tuned wettability of dynamic micromechanical sensors for an improved in-liquid operation

Partial wetting is a vital tool to improve the quality factor of dynamic micromechanical sensors operated in liquids owing to the reduced viscous damping. This technique employs meniscus formation which so far could only be stabilized for a hydrophobic sensory surface excluding biosensing applications. Here, we report on the geometrically tuned wettability of particular hybrid bridge resonators (HBR) with an integrated overhang structure. This allows low-loss operation irrespective of the sensory surface material. The impact of the overhang structure on wetting is explained in a simplified model. Experimental evidence is adduced operating the HBR coated with hydrophilic thin films in water. With an in-liquid quality factor Q of 91 and a small mass m≈5 ng of the HBR, the m/Q-ratio, which is proportional to the limit of detection for mass sensing, was significantly improved in comparison to immersed resonators presented so far.

Air damping of micro bridge resonator vibrating close to a surface with a moderate distance

The vibration of micro resonators is strongly influenced by the hydrodynamics of the surrounding fluid in the vicinity of a rigid wall. While most prior efforts to model this hydrodynamic loading have focused on squeeze film damping with very narrow gaps, in many practical applications, the resonators vibrate close to a surface with a moderate distance. Two recently developed models which deal with this problem are reviewed. Experiments by using a micro bridge resonator with a big range of gaps are performed at controlled gas pressures, and are compared with predictions from these theoretical models. The unsteady Navier–Stokes model yields the best agreement with experiments.

A System Based on Capacitive Interfacing of CMOS With Post-Processed Thin-Film MEMS Resonators Employing Synchronous Readout for Parasitic Nulling

Thin-film MEMS resonators fabricated at low temperatures can be processed on CMOS ICs, forming high-sensitivity transducers within complete sensing systems. A key focus for the MEMS devices is increasing the resonant frequency, enabling, among other benefits, operation at atmospheric pressure. However, at increased frequencies, parasitics associated with both the MEMS-CMOS interfaces and the MEMS device itself can severely degrade the detectability of the resonant peak. This work attempts to overcome these parasitics while providing isolation of the CMOS IC from potentially damaging sensing environments. To achieve this, an interfacing approach is proposed based on capacitive coupling across the CMOS IC passivation, and a detection approach is proposed based on synchronous readout. Results are presented from a prototype system, integrating a custom CMOS IC with MEMS bridge resonators. With the MEMS resonators fabricated in-house at 175°C on a separate substrate, readout results with multiple different resonators are obtained. In all cases, the IC enables detection with >20 dB SNR of resonant peaks that are only weakly detectable or undetectable directly using a vector-network analyzer (VNA).

An Improved Topology for the Current Fed Parallel Resonant Half Bridge Circuits Used in Fluorescent Lamp Electronic Ballasts

An improvement in the current fed parallel resonant half bridge (CFPRHB) circuits used in fluorescent lamp electronic ballasts is provided in this paper. The CFPRHB belongs to the self-oscillating family which includes the current fed push-pull and series resonant inverters, most of which are used in instant-start applications. However, many failure modes are related to the bypass capacitor according to an analysis of failed samples. In this paper, the operating functions of the existing topology in the steady state are analyzed and the main root cause of failure modes has been found. Comparisons between the two topologies are conducted in terms of the voltage stress of the bypass capacitor as well as the thermal and performance of the ballasts to verify the advantages of the proposed topology. It is found that the improved topology is capable of enhancing the reliability and reducing the cost of products without having a negative influence on the system performance.

Selection of Power Semiconductor Switches in Modified Half Bridge Resonant Inverter Fitted Induction Heater in Power Line for Less Harmonic Injection

<p>This paper presents an approach to minimize the harmonics contained in the input current of single phase Modified Half Bridge Resonant inverter fitted induction heating equipment. A switch like IGBT, GTO, and MOSFET are used for this purpose. It analyzes the harmonics or noise content in the sinusoidal input current of this inverter. Fourier Transform has been used to distinguish between the fundamental and the harmonics, as it is a better investigative tool for an unknown signal in the frequency domain. An exhaustive method for the selection of different power semiconductor switches for Modified Half Bridge Resonant inverter fed induction heater is presented. Heating coil of the induction heater is made of litz wire which reduces the skin effect and proximity effect at high operating frequency. With the calculated optimum values of input current of the system at a particular operating frequency, Modified Half Bridge Resonant inverter topology has been simulated using P-SIM software. To obtain the Input current waveforms through it, further analysis has been employed. From this analysis selection of suitable power semiconductor switches like IGBT, GTO and MOSFET are made. Waveforms have been shown to justify the feasibility for real implementation of single phase Modified Half Bridge Resonant inverter fed induction heater in industrial application.</p>

Step-Up DC/DC Transformer Based on LLC Resonant Full Bridge

In view of the LLC series resonant converter topology, it is well known as suitable for small and medium power application, the stabilization of output voltage and the environment of step-dowm. The scheme is proposed for a kind of the step-up DC/DC transformer based on LLC resonant full bridge. The detailed design method is given. The 3KW prototype is built. The experimental results show it has the characteristics of the constant current discharge, wide working frequency and high power desity, as well, the feasibility is verified.

Canonical-ensemble state-averaged complete active space self-consistent field (SA-CASSCF) strategy for problems with more diabatic than adiabatic states: charge-bond resonance in monomethine cyanines.

This paper reviews basic results from a theory of the a priori classical probabilities (weights) in state-averaged complete active space self-consistent field (SA-CASSCF) models. It addresses how the classical probabilities limit the invariance of the self-consistency condition to transformations of the complete active space configuration interaction (CAS-CI) problem. Such transformations are of interest for choosing representations of the SA-CASSCF solution that are diabatic with respect to some interaction. I achieve the known result that a SA-CASSCF can be self-consistently transformed only within degenerate subspaces of the CAS-CI ensemble density matrix. For uniformly distributed ("microcanonical") SA-CASSCF ensembles, self-consistency is invariant to any unitary CAS-CI transformation that acts locally on the ensemble support. Most SA-CASSCF applications in current literature are microcanonical. A problem with microcanonical SA-CASSCF models for problems with "more diabatic than adiabatic" states is described. The problem is that not all diabatic energies and couplings are self-consistently resolvable. A canonical-ensemble SA-CASSCF strategy is proposed to solve the problem. For canonical-ensemble SA-CASSCF, the equilibrated ensemble is a Boltzmann density matrix parametrized by its own CAS-CI Hamiltonian and a Lagrange multiplier acting as an inverse "temperature," unrelated to the physical temperature. Like the convergence criterion for microcanonical-ensemble SA-CASSCF, the equilibration condition for canonical-ensemble SA-CASSCF is invariant to transformations that act locally on the ensemble CAS-CI density matrix. The advantage of a canonical-ensemble description is that more adiabatic states can be included in the support of the ensemble without running into convergence problems. The constraint on the dimensionality of the problem is relieved by the introduction of an energy constraint. The method is illustrated with a complete active space valence-bond (CASVB) analysis of the charge/bond resonance electronic structure of a monomethine cyanine: Michler's hydrol blue. The diabatic CASVB representation is shown to vary weakly for "temperatures" corresponding to visible photon energies. Canonical-ensemble SA-CASSCF enables the resolution of energies and couplings for all covalent and ionic CASVB structures contributing to the SA-CASSCF ensemble. The CASVB solution describes resonance of charge- and bond-localized electronic structures interacting via bridge resonance superexchange. The resonance couplings can be separated into channels associated with either covalent charge delocalization or chemical bonding interactions, with the latter significantly stronger than the former.

Modeling and Control of a Resonant Dual Active Bridge with a Tuned CLLC Network

This paper proposes a linear state-space model for a phase-controlled resonant dual active bridge with a tuned capacitor-inductor-inductor-capacitor network. The proposed model is useful for fast simulation and for the estimation of state variables under large signal variation. The model is also useful for control design because the slow changing dynamics of the dq variables are relatively easy to control. Using the proposed model, a decoupled control scheme was designed which allows for the control of the high frequency link currents while also improving the soft switching range of the converter. Using steady-state relationships between state variables and the system inputs, the controller was simplified from three proportional integral (PI) controllers to a single PI controller. The controller was implemented on a low cost digital signal processor and verified experimentally. The experimental and simulation results showed the proposed model's usefulness for control design and fast simulation.

Hysteresis Current Control with Input Filter Design for High Frequency Series Resonant Full Bridge Inverter

This paper talks about the analysis of a high frequency series resonant inverter for using domestic and industrial induction heating purpose. It is a technique i.e. used for heat conductive materials hard and soft metals. Series Resonant inverters which operate at high frequency preferable for induction heating which normally works in 5-55KHz. High frequency series resonant inverters which is made up of Insulated Gate Bipolar Transistor (IGBT). Power control is obtained by Hysteresis Current Control and filter design is incorporated in the input power supply. Soft switching techniques is performed which minimizes switching losses and proper filter design minimizes harmonic injection in the power supply.

Hysteresis Current Control with Input Filter Design for High Frequency Series Resonant Full Bridge Inverter

Hysteresis Current Control with Input Filter Design for High Frequency Series Resonant Full Bridge Inverter

A New Resonant Bidirectional DC–DC Converter Topology

This paper presents a new resonant dual active bridge (DAB) topology, which uses a tuned inductor-capacitor-inductor (LCL) network. In comparison to conventional DAB topologies, the proposed topology significantly reduces the bridge currents, lowering both conduction and switching losses and the VA rating associated with the bridges. The performance of the DAB is investigated using a mathematical model under various operating conditions. Experimental results of a 2.5-kW prototype, which has an efficiency of 96% at rated power, are also presented with discussions to demonstrate the improved performance of the tuned LCL DAB topology. Results clearly indicate that the proposed DAB topology offers higher efficiency over a wide range of both input voltage and load in comparison to conventional DAB topologies.

Resonant frequency detection and adjustment method for a capacitive transducer with differential transformer bridge.

The capacitive transducer with differential transformer bridge is widely used in ultra-sensitive space accelerometers due to their simple structure and high resolution. In this paper, the front-end electronics of an inductive-capacitive resonant bridge transducer is analyzed. The analysis result shows that the performance of this transducer depends upon the case that the AC pumping frequency operates at the resonance point of the inductive-capacitive bridge. The effect of possible mismatch between the AC pumping frequency and the actual resonant frequency is discussed, and the theoretical analysis indicates that the output voltage noise of the front-end electronics will deteriorate by a factor of about 3 due to either a 5% variation of the AC pumping frequency or a 10% variation of the tuning capacitance. A pre-scanning method to determine the actual resonant frequency is proposed followed by the adjustment of the operating frequency or the change of the tuning capacitance in order to maintain expected high resolution level. An experiment to verify the mismatching effect and the adjustment method is provided.

Magnetostrictive stress reconfigurable thin film resonators for near direct current magnetoelectric sensors

The magnetic response of microdevices is significantly enhanced at structural resonance allowing for improved sensitivity and signal-to-noise ratio. Here, free-standing thin film CoFe bridge resonators have been fabricated and investigated. It is shown that the strong magnetic field dependence of the fundamental resonance frequency is a function of magnetic field orientation due to stress-induced anisotropy. These devices may offer a new approach for developing fully integrated resonant magnetic field sensing technology.

Ammonia binding to the oxygen-evolving complex of photosystem II identifies the solvent-exchangeable oxygen bridge (μ-oxo) of the manganese tetramer

The assignment of the two substrate water sites of the tetra-manganese penta-oxygen calcium (Mn4O5Ca) cluster of photosystem II is essential for the elucidation of the mechanism of biological O-O bond formation and the subsequent design of bio-inspired water-splitting catalysts. We recently demonstrated using pulsed EPR spectroscopy that one of the five oxygen bridges (μ-oxo) exchanges unusually rapidly with bulk water and is thus a likely candidate for one of the substrates. Ammonia, a water analog, was previously shown to bind to the Mn4O5Ca cluster, potentially displacing a water/substrate ligand [Britt RD, et al. (1989) J Am Chem Soc 111(10):3522-3532]. Here we show by a combination of EPR and time-resolved membrane inlet mass spectrometry that the binding of ammonia perturbs the exchangeable μ-oxo bridge without drastically altering the binding/exchange kinetics of the two substrates. In combination with broken-symmetry density functional theory, our results show that (i) the exchangable μ-oxo bridge is O5 {using the labeling of the current crystal structure [Umena Y, et al. (2011) Nature 473(7345):55-60]}; (ii) ammonia displaces a water ligand to the outer manganese (MnA4-W1); and (iii) as W1 is trans to O5, ammonia binding elongates the MnA4-O5 bond, leading to the perturbation of the μ-oxo bridge resonance and to a small change in the water exchange rates. These experimental results support O-O bond formation between O5 and possibly an oxyl radical as proposed by Siegbahn and exclude W1 as the second substrate water.