Multiport Network Research Articles

Systems Theory Approach to Stabilization of Multiport Networks

Systems Theory Approach to Stabilization of Multiport Networks

An improved time marching simulation of distributed multiport networks loaded with nonlinear devices

AbstractIn this paper, we present a method for obtaining stable time marching equations of distributed multiport networks with nonlinear loads. This method allows to highly decrease the number of frequency samples required by other stable TM methods. Stability is analyzed and ensured in the Z‐domain.

Single‐port and multi‐port frequency‐dependent network equivalents with numerically stable branches

This study proposes new methods for finding frequency-dependent network equivalents of power systems. Since stability of the time-domain solution is a major concern, additional constraints are added to ensure the stability in both single-port and multi-port network equivalents. For single-port problem, an equivalent circuit consisting of only passive elements is estimated to ensure passivity and, consequently, stability of the time-domain solution. For multi-port case, additional stable branches are added to fit the frequency response data with high accuracy while maintaining stability of the equivalent. Several case studies are considered to evaluate the performance of the proposed approaches. The simulation results prove the efficacy of the proposed methods for finding stable equivalent circuits with high accuracy.

On Existence of Equilibria of Multi-Port Linear AC Networks With Constant-Power Loads

In this paper we give an answer to the following question. Given a multi-port, linear ac network with instantaneous constant-power loads identify a set of active and reactive load powers for which there is no steady-state operating condition of the network—in this case, we say that the power load is inadmissible . The identification is given in terms of feasibility of simple linear matrix inequalities, and hence it can be easily verified with existing software. For one- or two-port networks, the proposed feasibility test is necessary and sufficient for load power admissibility with the test for the former case depending only on the network data. Two benchmark numerical examples illustrate our results.

Asynchronously coupled resonant junctions for diplexers and multiport filtering networks

AbstractThis article proposes the use of asynchronously coupled resonator junctions in the design of diplexers. This is to ease the control and implementation of the external couplings at the common port of an all‐resonator‐based diplexer. A comparison study has been performed between a conventional diplexer and the proposed diplexer. To further explore the possibilities of the proposed junction technique, a four‐port multiport filtering networks was proposed and designed to function as a double diplexer. Good agreements have been achieved between the measurements of the prototype devices and the simulations.

Advancements in the identification of passive RC networks for compact modeling of thermal effects in electronic devices and systems

AbstractWe deal with the problem of identifying the parameters of an equivalent lumped RC multiport network from time domain tabulated data of a corresponding distributed real eigenvalues problem, as obtained from either measurements or accurate simulation tools. A novel step response matrix identification procedure is proposed, based on the combination of an outer nonlinear least squares iteration for the relocation of time constants, and an inner convex programming cycle for the identification of the corresponding residue matrix terms, able to guarantee a priori the passivity property of the equivalent RC network. The structure of the algorithm and its principal functions connections are shown, and the mathematical features of the proposed formulation of the identification problem are accurately described and commented. Moreover, the possibility of getting direct synthesis of a Foster generalized concretely passive multiport, as a consequence of the optimal identification of a passive real eigenvalues model from data, is discussed. Since the technique is well suited (although not limited) to the reduced analysis of typical electro‐thermal problems, a set of significant case studies in this area is considered. In this way the algorithm present implementation is validated, also comparing it to previous well assessed methods, evidencing its large potential and value.

A Linear Multiport Network Approach for Elastically Coupled Underactuated Grippers

This paper presents a framework based on multiport network theory for modeling underactuated grippers where the actuators produce finger motion by deforming an elastic transmission mechanism. If the transmission is synthesized from compliant components joined together with series (equal force) or parallel (equal displacement) connections, the resulting multiport immittance (stiffness) matrix for the entire transmission can be used to deduce how the object will behave in the grasp. To illustrate this, a three-fingered gripper is presented in which each finger is driven by one of two linear two-port spring networks. The multiport approach predicts contact force distribution with good fidelity even with asymmetric objects. The parallel-connected configuration exhibited object rotation and was more prone to object ejection than the series-connected case, which balanced the contact forces evenly.

Two-port network theory applied to multi-body scattering

We have previously shown how Thevenin’s theorem may be used to help solve problems in linear acoustic scattering from a mobile body, by forming the solution as a superposition of the field scattered from the body when held immobile and the solution for radiation from the body in an otherwise quiescent field. For problems involving acoustic scattering from multiple mobile bodies, the basic approach can be extended by using multi-port network formalism, commonly used in engineering circuit analysis, to decompose the problem into a set of simpler problems. In this presentation we will first review two-port network theory, and then illustrate the approach using the problem of scattering from a pair of mobile, rigid spheres in an ideal plane progressive wave. In addition to solving for the velocities of the spheres, the resultant pressure field will also be determined. Finally, extension to higher-order systems will be discussed.

Bandwidth Analysis of Multiport Radio-Frequency Systems—Part II

We analyze the bandwidth over which power can be transferred from multiple radio-frequency sources to multiple loads through a passive multiport matching network. This is the second part of a two-part paper. In the first part, we introduce broadband multiport matching upper bounds and apply them to determine the bandwidth of loads and network structures whose scattering parameters can be expressed analytically with rational functions. In this second part, we apply the bounds to loads, such as antennas, whose scattering parameters are obtained by measurement or simulation. We focus on the effects of coupling on bandwidth. Since the bounds require frequency responses that are rational functions, we provide guidelines on how to obtain rational approximations for arbitrary loads. Complete derivations of the bounds are also provided.

Bandwidth Analysis of Multiport Radio Frequency Systems—Part I

When multiple radio frequency sources are connected to multiple loads through a passive multiport matching network, perfect power transfer to the loads across all frequencies is generally impossible. In this two-part paper, we provide analyses of bandwidth over which power transfer is possible. Our principal tools include broadband multiport matching upper bounds, presented herein, on the integral over all frequency of the logarithm of a suitably defined power loss ratio. In general, the larger the integral, the larger the bandwidth over which power transfer can be accomplished. We apply these bounds in several ways. We show how the number of sources and loads, and the coupling between loads, affect achievable bandwidth. We analyze the bandwidth of networks constrained to have certain architectures. We characterize systems whose bandwidths scale as the ratio between the numbers of loads and sources. The first part of this paper presents the bounds and uses them to analyze loads whose frequency responses can be represented by analytical circuit models. The second part analyzes the bandwidth of realistic loads whose frequency responses are available numerically. We provide applications to wireless transmitters where the loads are antennas being driven by amplifiers. The derivations of the bounds are also included.

ANÁLISIS Y OPTIMIZACIÓN DE LA ARQUITECTURA DE INTERCONEXIÓN MULTI-RAMALES BASADA EN LA MATRIZ DE TRANSFERENCIA MULTI-PUERTO

Multi-branch interconnect architecture (MBIA) is an effective way to achieve ultra-high-speed and ultra-high-integration electrical systems. However, the increasing frequency and complexity of operation result in critical signal integrity (SI) issues. The majority of existing studies focuses on modeling and analyzing the architecture itself but ignores corresponding termination effects thereby resulting in inaccurate analysis and ineffective optimization. To analyze and optimize MBIA accurately and effectively, the present study proposed a multi-port transfer matrix (MPTM) that considered termination effects into account, and a hybrid time-frequency domain strategy based on MPTM was also developed. First, MBIA was modeled as two cascaded generalized multi-port networks that respectively represented MBIA and its terminations. Second, MPTM was defined and MPTM-based strategy was derived. Finally, the principle and performance of the proposed strategies were demonstrated through an eight-DDR3 address interconnect of fly-by topology with a line rate of up to 667 Mbps. The simulation results verifies that the proposed MPTM represents a complete MBIA by considering termination effects and provides effective bias for analysis and optimization. By employing MPTF-based strategy, the eye height of DDR3 address signal in the case study attains an average growth rate of 80% of the original design. The results obtained in this study can be applied to obtain the optimal performance and stability of electrical systems involving MBIA. Keywords: Multi-branch interconnect, multi-port, transfer function,scattering matrix, termination effects

A new undervoltage load shedding method to reduce active power curtailment

Summary This study presents a new undervoltage load shedding (UVLS) method to reduce the amount of power curtailment in emergency conditions. At first, the effect of temperature is considered in an existing multiport network model. Then, a new centralized method called 2-factor UVLS is proposed. The proposed method considers the load reactive power and the multiport network model to determine the effective location of the UVLS. So as to take the actual conditions into account, the main challenges related to the centralized applications are evaluated and then a solution is introduced to overcome these challenges. The proposed 2-factor method and the multiport network model are implemented in the IEEE 57-bus test system, IEEE 118-bus test system, and a real 341-bus power system. Moreover, a comparison is made between 2-factor and sensitivity-based methods. The results show that the proposed 2-factor UVLS method needs less active power shedding than the multiport network model and sensitivity-based method.

The Minimum Norm Least-Squares Solution in Reduction by Krylov Subspace Methods

In recent years, model order reduction (MOR) of interconnect system has become an important technique to reduce the computation complexity and improve the verification efficiency in the nanometer VLSI design. The Krylov subspaces techniques in existing MOR methods are efficient, and have become the methods of choice for generating small-scale macro-models of the large-scale multi-port RCL networks that arise in VLSI interconnect analysis. Although the Krylov subspace projection-based MOR methods have been widely studied over the past decade in the electrical computer-aided design community, all of them do not provide a best optimal solution in a given order. In this paper, a minimum norm least-squares solution for MOR by Krylov subspace methods is proposed. The method is based on generalized inverse (or pseudo-inverse) theory. This enables a new criterion for MOR-based Krylov subspace projection methods. Two numerical examples are used to test the PRIMA method based on the method proposed in this paper as a standard model.

Impulse Response Optimization of Band-Limited Frequency Data for Hybrid Field-Circuit Simulation of Large-Scale Energy-Selective Diode Grids

Recently, large-scale diode grids have received much attention with regard to spatial electromagnetic (EM) field protection of electronic systems. The distributed nature of diode grids and the large number of elements (usually hundreds or even more) pose a challenging problem for numerical modeling. In this paper, a hybrid field-circuit simulation combining the method of moments and a causal convolution technique is proposed for transient analysis of such diode grids. Emphasis is put on the treatment of causality and passivity violations caused by incorporation of a frequency-dependent distributed multiport network into a circuit solver. Specifically, when considering a large-scale multiport network, an enhanced causal correction approach with minor passivity violations is proposed to improve the simulation accuracy and stability. For validation, $\text{3} \times \text{3}$ and $\text{9} \times \text{9}$ grid arrays excited by incident fields are investigated, and the results provided by the proposed method are compared to the simulation results of commercial software. Furthermore, an EM application example with a $\text{15} \times \text{15}$ diode grid is demonstrated. The simulations show a field-intensity-dependent transmission of diode grids which is suitable, e.g., for EM protection of communication systems with sensitive electronics.

An Integrated Filtering Antenna Array With High Selectivity and Harmonics Suppression

In this paper, a new design of an antenna array with integrated functions of filtering, harmonics suppression, and radiation is proposed. The device employs a multi-port network of coupled resonators, which is synthesized and designed as a whole to fulfill the functions of filtering, power combination/division, and radiation. The 50- $\Omega $ interfaces between the cascaded filter, power divider, and antenna in traditional RF front-ends are eliminated to achieve a highly integrated and compact structure. A novel resonator-based four-way out-of-phase filtering power divider is proposed and designed. It is coupled to the patch array, rendering a fourth-order filtering response. The coupling matrix of the resonator network is synthesized. The physical implementations of the resonators and their couplings are detailed. Compared to a traditional patch array, the integrated filtering array shows an improved bandwidth and frequency selectivity. In addition, the harmonic of the antenna array is suppressed due to the use of different types of resonators. To verify the concept, a $2\times 2$ filtering array at S-band is designed, prototyped, and tested. Good agreement between simulations and measurements has been achieved, demonstrating the integrated filtering antenna array has the merits of wide bandwidth, high frequency selectivity, harmonics suppression, stable antenna gain, and high polarization purity.

Corrections to “Synthesis of Multiport Networks Using Port Decomposition Technique and Its Applications”

In the above paper [1] , Fig. 4 is incorrect and should be replaced with the version published in this Letters.

다단자망 알고리즘을 이용한 급전시스템의 무효전력 보상 모델링 및 시뮬레이션

The power supply system in Korean electrified railway has adopted AT feeding. If a fault occurs in some substation for any reason, the vicinity substation must feed electric power on the outage substation through catenary. So, the feeding distance grows twice of the normal state at extended feeding condition. If substation’s feeding distance is longer than normal condition, the catenary impedance and train to supply electric power from the substation. Therefore, the severe voltage drop can occur and power supply shall be not allowed. This paper presents the model of compensator against voltage drop using multi-port network algorithm. Whole traction power supply system can be analyzed with this model. Computer simulation including this model is performed based on real train schedule and increased schedule in case studies.

Synthesis of Multiport Networks Using Port Decomposition Technique and its Applications

A systematic approach to synthesize multiport ( $N$ -port) network with desired characteristics, for a given network topology, has been proposed. The heart of the algorithm lies with a novel port decomposition technique introduced here, wherein a reduced two-port network (2PN) is obtained by short-circuiting the remaining $N-2$ ports of the original topology. This reduced network is easily analyzed in terms of its unknown design parameters and can be compared with the known characteristics to provide a subset of design equations. Iteratively proceeding with this approach, one can obtain the required synthesis equations for any multiport network, even when there exists no plane of symmetry. Utilizing this algorithm, four theorems pertaining to multiport network synthesis have been proposed. The first and second theorems establish the synthesis guidelines of an arbitrary-phased rat-race and branch-line type coupler having unequal (or equal) power division at the output ports, with a ring type topology consisting of arbitrary building blocks. The third theorem deals with the synthesis of a five-port network, and the final one provides the design equations for arbitrary phase difference coupler involving coupled lines.

Extraction of High-Frequency Phase-to-Phase Coupling in AC Machine Using Mixed-Mode Network Parameters

This paper proposes a method that extracts the phase-to-phase coupling of the three-phase stator winding of an ac motor for high-frequency characterization. Under the assumption of a symmetric structure, the multiport network parameters are obtained by the conversion of two-port mixed-mode network parameters. The proposed method simplifies the calculation to extract the impedance parameters of the three-phase winding structure without the full six-port measurement. Using the extracted parameters, we can construct a T-equivalent circuit and the corresponding transmission line model of a phase line, where the phase-to-phase coupling is distinguished from the self-coupling terms. Through the constructed equivalent circuit, the effect of the phase-to-phase coupling is clearly observed by comparing the high-frequency transmission line parameters. To verify the proposed method, the calculated input impedance is compared with the measured data.

Noise Characterization of Differential Multi- Element Multiport Networks - the Wave Approach

Abstract In this paper there is presented and discussed a general analysis method for noise characterization of noisy multielement multiport differential networks. It is based on mixed mode, differential and common mode, noise waves representation of noise, generalized mixed-mode scattering parameters and generalized mixed-mode noise wave correlation parameters for the network. There are derived analytical relation between the noise figure for a given output port and the noise matrix and the scattering parameters of the network, as well as the correlations between the input port noise waves. The signal to noise ratio degradation factor is derived and discussed, too. Presented results can be implemented directly in a CAD software for noise analysis of differential microwave multi-element multiport networks with differential as well as with conventional single ended ports.