Three-port Model Research Articles

Three-port impedance model and validation of VSCs for stability analysis

Modern power system is undergoing a paradigm shift from the synchronous generators-based system to the power electronics converters-dominated system. With the high penetration of converters, serious stability problems are provoked, especially the wideband oscillations (e.g., sub-synchronous oscillations, harmonic oscillations, etc). Various studies have been conducted in this respect, while most of them separate the ac-side stability with the dc-side stability. However, for the stability analysis of the hybrid AC/DC grid, it is necessary to consider the converter's ac-side and dc-side, simultaneously. In this paper, the stability analysis of voltage source converters (VSCs) considering both ac and dc dynamics is carried out. At first, the threeport AC/DC admittance model of VSCs is established, and the corresponding measurement method from simulations is presented to validate its accuracy. Secondly, based on such three-port model, two stability analysis methods are presented: the one is based on the system open-loop model, where the stability can be judged via the Generalized Nyquist Criterion (GNC); the other one is based on the system closed-loop model, whose stability can be predicted through the pole-zero calculation. At last, a test AC/DC system is built in MATLAB/Simulink, by which the effectiveness of the three-port model-based stability analysis is validated.

Wideband Dual Circularly Polarized Antipodal Septum Antenna for Millimeter-Wave Applications

A millimeter-wave (mm-Wave) wideband dual circularly polarized (CP) antipodal septum antenna is proposed. By introducing two antipodal septum blames in widened rectangular waveguide and the corresponding feeding network, the operating bandwidth of the septum antenna is enhanced. The working principle of the generation process of dual CP is explained by a three-port model with three excitation conditions. In addition, the asymmetrical radiation pattern of the classical polarizer consisting of square waveguide and single septum caused by the high-order modes is explained and eliminated. To verify the design, the proposed antenna has been fabricated and measured. An operating bandwidth of 37.4% for reflection coefficients less than −13.8 dB, isolation better than 22 dB, and axial ratio (AR) value less than 3 dB is achieved.

Six-Plate Capacitive Coupler to Reduce Electric Field Emission in Large Air-Gap Capacitive Power Transfer

This paper proposes a six-plate capacitive coupler for large air-gap capacitive power transfer to reduce electric field emissions to the surrounding environment. Compared to the conventional four-plate horizontal structure, the six-plate coupler contains two additional plates above and below the inner four-plate coupler to provide a shielding effect. Since there is a capacitive coupling between every two plates, the six-plate coupler results in a circuit model consisting of 15 coupling capacitors. This complex model is first simplified to an equivalent three-port circuit model, and then to a two-port circuit model which is used in circuit analysis and parameter design. This six-plate coupler can eliminate the external parallel capacitor in the previous LCLC topology, which results in the LCL compensation and reduces the system cost. Due to the symmetry of the coupler structure, the voltage between shielding plates is limited, which reduces electric field emissions. Finite element analysis by Maxwell is used to simulate the coupling capacitors and electric field distribution. Compared to the four-plate horizontal and vertical structures, the six-plate coupler can significantly reduce electric field emissions and expand the safety area from 0.9 to 0.1 m away from the coupler in the well-aligned case. A 1.97 kW prototype is implemented to validate the six-plate coupler, which achieves a power density of 1.95 kW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a dc-dc efficiency of 91.6% at an air-gap of 150 mm. Experiments also show that the output power maintains 65% of the well-aligned value at 300 mm X misalignment, and 49% at 300 mm Y misalignment.

Noise and conversion performance of a high-Tc superconducting Josephson junction mixer at 0.6 THz

This letter presents both theoretical and experimental investigations on the noise and conversion performance of a high-Tc superconducting (HTS) step-edge Josephson-junction mixer at the frequency of 0.6 THz and operating temperatures of 20–40 K. Based on the Y-factor and U-factor methods, a double-sideband noise temperature of around 1000 K and a conversion gain of −3.5 dB were experimentally obtained at 20 K. At the temperature of 40 K, the measured mixer noise and conversion efficiency are around 2100 K and −10 dB, respectively. The experimental data are in good agreement with the numerical analysis results using the three-port model. A detailed performance comparison with other reported HTS terahertz mixers has confirmed the superior performance of our presented mixer device.

Three-Port Model of a Modern MOS Transistor in Millimeter Wave Band, Considering Distributed Effects

Distributed nature of an MOS transistor becomes significant in high frequencies, especially in the millimeter wave band. Two types of distributed effects are encountered in an MOS transistor: the distributed effect along the transistor channel, referred as nonquasi static (NQS) effect, and the distributed effect along the gate finger. We denote the former as lateral distributed effect and the later as longitudinal distributed effect (LDE). Lateral distributed effect has been studied in many works and has been considered either accurately or approximately in the available MOS small-signal models. However, LDEs have not accurately been accounted for, except for few works in which an MOS transistor has been analyzed using transmission line approach to derive two-port ${Y}$ parameters of the transistor. Unfortunately, the two-port distributed model is not useful when the transistor is used in common gate, common drain, or cascode configurations. In this paper, we have developed a new three-port distributed model of an MOS transistor to accurately capture the LDEs. Furthermore, the proposed model can be used in conjunction with new Berkeley short-channel IGFET model (BSIM) radio frequency (RF) small-signal models, such as BSIM4.7 and BSIM6. To evaluate the proposed model, we have used Taiwan Semiconductor Manufacturing Company 90 nm RF-CMOS technology parameters. Our results show that LDE is considerably more significant than NQS effect in millimeter wave band, in the case of a short channel MOS transistor with long gate finger. This reveals the importance of LDEs in RF MOS transistor models, especially in millimeter wave band applications.

High-Tc superconducting Josephson mixers for terahertz heterodyne detection

We report on an experimental and theoretical study of the high-frequency mixing properties of ion-irradiated YBa2Cu3O7 Josephson junctions embedded in THz antennas. We investigated the influence of the local oscillator power and frequency on the device performances. The experimental data are compared with theoretical predictions of the general three-port model for mixers in which the junction is described by the resistively shunted junction model. A good agreement is obtained for the conversion efficiency in different frequency ranges, spanning above and below the characteristic frequencies fc of the junctions.

Research on the beam-wave interaction theory of folded waveguide traveling wave tubes based on three-port network model

A general equivalent model for slow-wave structure is established in this paper, if the unit cell of the periodic slow-wave structures is represented by a three-port network and the parameters of the equivalent model are determined by a high frequency structural simulator. In this method, there is no need to find a complicated equivalent circuit, and the fields in the tunnels can be calculated by the high frequency software directly. Therefore, the three-port network model is simpler than the analytic method and no more complex than the common equivalent circuit model. A one-dimensional nonlinear beam-wave interaction theory suitable for the folded-waveguide traveling wave tubes (TWTs) is accomplished based on the three-port network model. And a one-dimensional nonlinear beam-wave interaction code, which complies with the MATLAB language, is used to simulate a folded-waveguide TWT. The difference between the results obtained from the code and the experimental data is less than 10%. This theory can be used in the design of novel folded-waveguide TWTs and research on nonlinear simulations.

Resonant pressure wave setup for simultaneous sensing of longitudinal viscosity and sound velocity of liquids

Increasing demands for online monitoring of liquids have not only resuted in many new devices relying on well-established sensing parameters like shear viscosity but also initiated research on alternative parameters. Recently, the longitudinal viscosity has been evaluated as a promising candidate because the devices arising enable the bulk of the liquid to be probed rather than a thin surface layer. We report on a multi-purpose sensor which allows simultaneous measurement of the sound velocity and longitudinal viscosity of liquids. The device embodiment features a cube-shaped chamber containing the sample liquid, where one boundary surface carries a flush-mounted PZT transducer. In operation, the transducer induces standing, resonant pressure waves in the liquid under test. We studied the influences of sound velocity and longitudinal viscosity on the generated pressure waves by means of the Navier–Stokes equation for adiabatic compressible liquids and exploited both parameters as the basic sensing mechanism. Furthermore, a three-port network model describing the interaction of the transducer and sample liquid was developed in order to be applied for extracting the parameters of interest from the raw measurement data. Finally, we demonstrate the device and method by carrying out and discussing test measurements on glycerol–water solutions.

Toward terahertz heterodyne detection with superconducting Josephson junctions

We report on the high-frequency mixing properties of ion irradiated YBa2Cu3O7 Josephson junctions. The frequency range, spanning above and below the characteristic frequencies fc of the junctions, permits a clear observation of the transition between two mixing regimes. The experimental conversion gain was found to be in good agreement with the prediction of the three-port model. Finally, we discuss the potential of the junctions to build a Josephson mixer operating in the terahertz frequency range.

Three-port impedance model of a piezoelectric bar element: Application to generation and damping of extensional waves

A straight bar element containing piezoelectric members is viewed as a linear system with one electrical and two mechanical ports where it can interact with external electrical and mechanical devices through voltage, current, forces and velocities. A generalized force vector, with one voltage and two forces as elements, is expressed as the product of an impedance matrix and a generalized velocity vector, with one current and two velocities, as elements. Due to symmetry and reciprocity, this matrix is defined by four of its nine elements. Two applications are considered for a piezoelectric bar element (PBE) that constitutes a part of a long elastic or viscoelastic bar, viz. generation and damping of extensional waves in the bar. In the first, the PBE is driven by a given input voltage or by the output voltage from a linear power amplifier. In the second, the PBE supplies an output voltage to an external load. In numerical simulations carried out for a specific laminated PBE, an elastic bar, a serial RL load and a bell-shaped incident wave, the highest fraction of wave energy dissipated was 8.1%. This is much less than the 50% achievable for a harmonic wave under condition of electrical impedance matching.

Damping of elastic strain waves by means of a piezoelectric bar element feeding an external RL circuit

Damping of elastic strain waves in an aluminum bar by means of a pair of piezoelectric members bonded to the bar and loaded by an external RL circuit is studied. Experimental results are compared with theoretical results based on a three-port impedance model for the laminated piezoelectric bar element (PBE). According to this model, the PBE is viewed as a linear system with one electrical and two mechanical ports at which interactions with external devices, e.g., the external parts of the aluminum bar, can take place. The two constitutive equations of the piezoelectric material, the dynamics of the piezoelectric members and the bar, and the dynamics of the resistive-inductive load are taken into account. The experimental results are below the theoretical ones by a few percent for the reflected and transmitted strain waves, by 6–11% for the voltage and current generated, and by 12–19% for the power and energy delivered to the load. This indicates that there are energy losses in the PBE and the external parts of the bars that have not been accounted for in the model. Such losses may be due to, e.g., viscoelastic shear, dielectric losses and generation of bending waves.

Characterization of the Body Node in PD SOI MOSFETs Using Multiport VNA Measurements

This paper describes, for the first time, how the use of multiport vector network analyzer measurements can be exploited to provide a full small-signal characterization of body-contacted partially depleted silicon-on-insulator (SOI) MOSFETs. By combining information that was obtained from both three-port (with one body connection) and four-port (with two body connections) devices, the method successfully determines the value of the body resistance and the intrinsic and extrinsic body capacitances in these devices for any given bias condition. A complete three-port model including the body node is therefore obtained and shown to closely match with ac measurements. The extraction technique is shown to be accurate, straightforward, and time effective, which makes it an ideal characterization tool, for instance, to parameterize compact models or investigate the quality of new SOI technologies.

Three-port electrical and optical model for LiTaO3 electro-optic probe with CPW test structure

A three-port electrical and optical model of LiTaO3 probes with a high-bandwidth coplanar waveguide (CPW) test structure is developed in this paper. The three-port model is constructed by combining the full wave field simulation and the neural network techniques. The three-port model has the same accuracy as the full wave modeling, but its characteristics are directly obtained from the neural network weighting parameters rather than the complicated full wave simulation. With this model, both invasiveness and waveform distortion in the external E-O sampling can be de-embedded.

A theoretical three-port coaxial-line rectangular-waveguide model and its application to millimeter-wave structures

A theoretical three-port model for a coaxial-line rectangular-waveguide junction is described and evaluated using several different realistic millimeter-wave mount structures. The model is found to be usable with good accuracy over a large variation in mount dimensions. The model is specifically applied in calculations of the embedding impedance seen by the diode in a millimeter-wave frequency multiplier. The three-port model is an improvement over simpler models hitherto used for devices such as millimeter-wave frequency multipliers because it takes into account all parameters in the mount.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Harmonic mixing in a superconducting tunnel junction

A theoretical analysis of harmonic mixing in a quasiparticle tunnel junction at Vbias=0 shows that harmonic mixing for submillimeter frequencies is a viable alternative to fundamental mixing. It is also shown that the signal gain from the first harmonic above the pump frequency to the intermediate frequency is independent of the embedding admittance at the pump frequency. In fact, we show that the five-port model reduces to the three-port model as a result of the inversion symmetry of the I-V curve and, moreover, no large-signal analysis is necessary. Full simulations of harmonic mixing using a five-port model confirm these results. The simulations have been done for the case of a superconductor-insulator-normal junction in which there is no pair current interference. For this type of harmonic mixer we show that the local oscillator (LO) power requirement can be less than a fundamental mixer operating at the same signal frequency, which is particularly useful in circumventing the problems of high-frequency LO power generation.

A new development of an equivalent circuit model for magnetostatic forward volume wave transducers

A three-port equivalent circuit model of microstrip transducers used for the generation and detection of magnetostatic forward volume waves (MSFVW) is derived from fundamental physical considerations. In this circuit model, each microstrip MSFVW transducer is modeled as a three-port circuit incorporating a frequency-dependent series reactance, a frequency-dependent lossless transformer, and a lossy transmission line. Circuit parameters are determined in closed form by the use of solutions of pertinent boundary-value problems. The effects of parasitics, for example, capacities of bonding pads, are easily taken into account. Some typical transducer configurations are analyzed numerically. The three-port model developed is in excellent agreement with experiments. The model can be applied directly to nonuniform arrays of microstrips weighted by varying the separation between strip centers and the widths of successive strips or reversing the current direction of some groups of strips.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Accurate experimental and theoretical comparisons between superconductor-insulator-superconductor mixers showing weak and strong quantum effects

We have made a systematic study of the gain and noise in superconductor-insulator-superconductor mixers employing Ta based, Nb based, and Pb-alloy based tunnel junctions. These junctions displayed both weak and strong quantum effects at a signal frequency of 33 GHz. The effects of energy gap sharpness and subgap current were investigated and are quantitatively related to mixer performance. Detailed comparisons are made of the mixing results with the predictions of a three-port model approximation to the Tucker theory. We have measured mixer performance with a novel test apparatus which is accurate enough to allow for the first quantitative tests of theoretical noise predictions. We find that the three-port model of the Tucker theory underestimates the mixer noise temperature by a factor of about 2 for all of our mixers. In addition, predicted values of available mixer gain are in reasonable agreement with experiment when quantum effects are weak. However, as quantum effects become strong, the predicted available gain diverges to infinity, which is in sharp contrast to the experimental results. Predictions of coupled gain do not always show such divergences.

An Analysis of an Equivalent Circuit Model for an Interdigital Surface-Acoustic-Wave Transducer

This paper presents a new and simplified equivalent circuit model for an IDT. The model developed here provides more accuracy than the well-known crossed field Smith-model, since it contains the energy storage effect in addition to usual secondary effects. By applying the image parameter theory to the new model, the admittance matrix Yij of the equivalent three-port model for an N-pair IDT has been derived in concise closed form. As an application, the relations of the radiation conductances to metallization ratios for an IDT are investigated.

A lattice model of the thickness-mode piezoelectric transducer

Abstmct-The development of a new three-port model of the thickness-mode piezoelectric transducer, employing linear systems theory, is presented. A discrete bidirectional lattice is used to describe mechanical wave propagation and continuous transfer functions to represent the electrical parameters. When presented in block-diagram format, an extremely valuable insight is gained into the nature of piezoelectric interaction. The lattice concept is extended to the analysis of multilayered structures and, when implemented in the discrete time domain, close agreement with experimental data is obtained. A number of experimental and simulation results are included for comparison. I. INTRODUCTION ONVENTIONAL models of the thickness-mode piezoelectric transducer invariably utilize transmissionline analogs in which the electromechanical properties of the system are evaluated by means of electrical network concepts. Examples of this include the equivalent circuits of Mason [l] and the more recent KLM [2] model, which uses a center-tapped transmission line to model acoustic wave propagation. In this form both models are also readily adapted for the analysis of multilayered transducer structures. However, electrical analogs possess some disadvantages which limit their flexibility when applied to piezoelectric transducer modelling [3]. Physical insight into the nature of the transduction process is often masked, and as a'result the influence of external electrical and mechanical load conditions on transducer behaviour is difficult to determine. To overcome this, an alternative strategy has been proposed by Hayward [3] who adopted a systems feedback approach to

Rapid solutions to the transient response of piezoelectric elements by z-transform techniques

Calculation of the transient response of piezoelectric elements by analytical means is only possible for a small range of exciting functions for which simple Laplace transforms exist. Calculation tends to be tedious due to the large number of terms which must be evaluated. A method is presented by which the Laplace transformed three-port model of a piezoelectric element is approximated by a discrete time system by application of the z-transform. A recurrent time domain solution is developed and this is applied in the manner of a digital filter to a variety of exciting functions. The method has the advantage that the response to any real input can be evaluated and it is thus of considerable use in the testing of piezoelectric elements or the measurement of their physical properties in transient tests. Experimental results are presented which show that the technique is reliable and accurate.