Two-port Network Theory Research Articles

Remaining Opportunities in Capacitive Power Transfer Based on Duality With Inductive Power Transfer

Wireless power transfer (WPT) has proven to be an effective solution for electric vehicle charging. As two mainstream near-field WPT technologies, inductive and capacitive power transfer (IPT and CPT) have many similarities. This paper aims to explore the remaining opportunities in CPT systems, not yet reported in existing literature, based on duality with the mature IPT technology. First, a generic modeling method based on two-port network theory is proposed, which contributes to unified modeling and analysis for both inductive and capacitive couplings. Then, power transfer mechanism of IPT and CPT couplers is compared, and unified transfer efficiency is derived, promoting CPT theory developments. Last, the duality between existing IPT and CPT circuits is demonstrated in two aspects: compensation circuit configuration and resonant relationship. 14 CPT topologies are derived based on duality with the existing 7 mainstream IPT circuits, of which 11 circuits do not exist in literature, offering future opportunities in CPT. Detailed comparison and evaluation of the derived 14 CPT circuits are conducted, and high-performance circuits are recommended. As a demonstration, a case study of a 2.1kW 3MHz CPT system is implemented in hardware based on the newly proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SS</i> topology. This example system achieves a peak efficiency of 93.19% with the predicted circuit properties of load-independent constant-voltage (CV) output and zero-phase-angle (ZPA) property.

Resonance magnetoelectric effect analysis and output power optimization of nonlinear magnetoelectric transducer model

Magnetoelectric composites comprised of piezoelectric and magnetostrictive materials, are widely used in magnetic field sensing, energy harvesting, and transducers. This work establishes a finite element model of a laminated magnetoelectric transducer coupled with magneto-elastic-electric fields based on the constitutive equation of the nonlinear magnetostrictive material. Then, the resonant magnetoelectric effect under different biased magnetic fields is studied. Based on the equivalent circuit model and the two-port network theory, the magnetoelectric coefficient and the equivalent source impedance under the resonant state are completely solved for the first time. Introducing optimized L-section matching networks between the magnetoelectric transducer and the load resistor can increase the load power and expand the operating bandwidth. The simulation results are consistent with the data in the literature, thus confirming the accuracy and effectiveness of the model. The simulation results demonstrate that the magnetoelectric coefficient reaches 51.79 V/(cm·Oe) at 51.4 kHz and 450 Oe bias magnetic field, and the ultimate output power of –3.01 dBm at 50.4 kHz and 350 Oe bias magnetic field. To ensure the load power, the power increase of 2.30 dB and the bandwidth expansion of 2.27 times are achieved by optimizing the matching network. The nonlinear finite element model in this work takes into account of the magnetoelectric effect under the acoustic resonance state and quantifies the ultimate output power. The magnetoelectric transducer model can obtain high magnetoelectric coefficient, load power, and power density in a small volume, providing a significant advantage in terms of equilibrium. The research results are of great importance in guiding the design and performance improvement of miniaturized magnetically coupled wireless power transfer systems.

Failure quantitative assessment approach to MOSFET power device by detecting parasitic parameters

With the emerging wide bandgap (WBG) semiconductor development, the increasing power density and efficiency of power electronic converters may cause more switching oscillation, electromagnetic interference noise, and additional power loss, further increasing the probability of device failure. Therefore, determining and quantifying the failure of a metal-oxide-semiconductor-field-effect transistor (MOSFET), which assembled using WBG semiconductor in some applications, is crucial to improving the reliability of a power converter. This study proposes a novel failure quantitative assessment approach based on MOSFET parasitic parameters. According to the two-port network theory, MOSFET is equivalent to some second-order RLC circuits composed of independent inductances, capacitances, and resistances in series. Then, the frequency-domain impedance associated with the physical failure of MOSFET is identified through frequency domain reflectometry. Accelerated aging and bond wires cut-off experiments are employed to obtain various quality states of the MOSFET device. Result shows that the MOSFET quality level and its number of bond wire lift-offs can be quantified effectively. Drain-to-source on-resistance (RDS(on)) that normally represents the MOSFET quality shows a positive linear function relationship on drain-to-source parasitic resistance (RD + RS) during the quality degradation proceeding. This finding matches with the correlation established between RDS (on) and RD + RS in theory. Meanwhile, source parasitic inductance (LS) increases with the severity of bond wires faults, and even the slight fault shows a high sensitivity. The proposed approach would be an effective quality screening technology for power semiconductor devices without power on treatment, which can effectively avoid the impact of junction temperature and test conditions (current and voltage) on test results, and does not need to design additional test circuits. The test frequency range we used in this approach was 10–300 MHz, which to some extent is suitable for providing an on-line quality monitoring technology for high-frequency WBG power devices manufacturing.

Directional element evaluation applied to half-wavelength transmission lines

In this paper, a careful analysis of directional element behavior applied to a half-wavelength transmission line (HWL) is presented. Single line-to-ground (SLG) faults were applied, varying loading conditions and fault resistance. A commercial relay was used. Two directional elements were considered: 32QG and 32V. With the aim of obtaining directional element setting parameters, a Python program based on two-port network theory was developed. The simulations were also performed in a hardware-in-the-loop (HIL) environment. It was observed that only the element 32V operated properly throughout the system during SLG fault conditions. It can be concluded that the conventional directional element algorithm can be applied to a system with a half-wavelength transmission line under the above-mentioned fault condition.

Brass instruments as a cascade of two-port networks: Transfer functions, chain parameters, and power efficiency in theory and practice.

This paper investigates how two-port network theory as a means for system identification can be applied to the analysis of brass instruments. A special focus is placed on the energy conversion efficiency as this is limited by inner damping, which receives much attention by expert players and makers of brasses. Theory suggests that a reconstruction of the 2 × 2 matrix representing the network requires input impedance and transfer function for two different boundary conditions. Besides the normal case of free sound radiation, instruments are also analyzed with the bell closed by a spherical cap. For this purpose, a customized 3D-printed spherical cap was fabricated and attached to the bell. Four measured spectra and the passivity condition over-determine the set of system equations. It is shown how to take advantage of this freedom when analyzing wind instruments. Measurements and simulations of a trumpet and a trombone are presented and compared.

LCC-S-Based Integral Terminal Sliding Mode Controller for a Hybrid Energy Storage System Using a Wireless Power System

Unlike the plug-in charging system, which has safety concerns such as electric sparks, wireless power transfer (WPT) is less-time consuming, is environmentally friendly and can be used in a wet environment. The inclusion of hybrid energy storage systems (HESSs) in electric vehicles (EVs) has helped to increase their energy density as well as power density. Combined with static wireless power transfer, a WPT–HESS system is proposed in this article. The HESS system includes a battery and supercapacitor (SC) connected to a WPT system through DC–DC converters. To ensure a stable DC bus voltage, an inductor–capacitor–capacitor series (LCC-S) compensation network has been implemented in the WPT system. Utilizing the two-port network theory, the design equations of the LCC-S compensation network are derived in order to realize the maximum efficiency point for the WPT system. To ensure that the WPT system operates at this maximum efficiency point and that the SC is charged to its maximum capacity, an energy management system (EMS) has been devised that generates reference currents for both the SC and battery. An integral terminal sliding mode controller (ITSMC) has been designed to track these reference currents and control the power flow between the energy storage units (ESUs) and WPT system. The stability of the proposed system is validated by Lyapunov theory. The proposed WPT–HESS system is simulated using the MATLAB/Simulink. The robustness of the ITSMC against the widely used proportional–integral–derivative (PID) and sliding mode controller (SMC) is verified under abrupt changes in the associated ESU resistance and reference load current. Finally, the simulations of the WPT–HESS system are validated by controller hardware-in-loop (C-HIL) experiments.

Fundamental Issues in Magnetoelectric Transducers: Magnetic Field Sensing Versus Wireless Power Transfer Systems

This paper presents theoretical analysis on fundamental performances of two configurations of magnetoelectric transducers that are used the most in practice, longitudinal-longitudinal and longitudinal-transverse modes, with a focus on magnetic field sensing and wireless power transfer applications. Based on equivalent circuit models and two-port network theory, we derive explicit closed-form solutions for the magnetoelecitric voltage coefficient and the power delivered to a load. We reveal that although the former configuration exhibits some advantages of utilizing as a sensing system, there is no difference in the maximum output power obtained from the two methods. The question on how to reach the upper bound on transferred power is also discussed. The findings can be used as a generalized framework to design an optimal system, depending on desired applications.

Two-Port Network Modeling and Stability Analysis of Grid-Connected Current-Controlled VSCs

Converter–grid interactions tend to bring in frequency-coupled oscillations that deteriorate the grid stability and power quality. The frequency-coupled oscillations are generally characterized by means of multiple-input multiple-output (MIMO) impedance models, which requires using the multivariable control theory to analyze resonances. In this article, instead of the MIMO modeling and analysis, the two-port network theory is employed to integrate the MIMO impedance models into a single-input single-output (SISO) open-loop gain, which is composed by a ratio of two SISO impedances. Thus, the system resonance frequency can be readily identified with Bode plots and the classical Nyquist stability criterion. Case studies in both simulations and experimental tests corroborate the theoretical stability analysis.

LCC-S Based Discrete Fast Terminal Sliding Mode Controller for Efficient Charging through Wireless Power Transfer

Compared to the plug-in charging system, Wireless power transfer (WPT) is simpler, reliable, and user-friendly. Resonant inductive coupling based WPT is the technology that promises to replace the plug-in charging system. It is desired that the WPT system should provide regulated current and power with high efficiency. Due to the instability in the connected load, the system output current, power, and efficiency vary. To solve this issue, a buck converter is implemented on the secondary side of the WPT system, which adjusts its internal resistance by altering its duty cycle. To control the duty cycle of the buck converter, a discrete fast terminal sliding mode controller is proposed to regulate the system output current and power with optimal efficiency. The proposed WPT system uses the LCC-S compensation topology to ensure a constant output voltage at the input of the buck converter. The LCC-S topology is analyzed using the two-port network theory, and governing equations are derived to achieve the maximum efficiency point. Based on the analysis, the proposed controller is used to track the maximum efficiency point by tracking an optimal power point. An ultra-capacitor is connected as the system load, and based on its charging characteristics, an optimal charging strategy is devised. The performance of the proposed system is tested under the MATLAB/Simulink platform. Comparison with the conventionally used PID and sliding mode controller under sudden variations in the connected load is presented and discussed. An experimental prototype is built to validate the effectiveness of the proposed controller.

Modeling the AC–DC Transfer Difference of Wideband Cage-Type Current Shunts

A cage-type, current-shunt construction design was adopted in this article as prospectively having a wide bandwidth. A lumped equivalent circuit model for current shunts assembled according to this design is described here. The ac–dc transfer differences of shunts with the nominal currents from 0.5 to 20 A are computed using standard two-port network theory. Cage-type current shunts were constructed and tested to validate the model. The measured ac–dc current transfer differences agree with the predicted values within the standard uncertainties in the whole frequency range of interest (10 Hz–100 kHz).

Two-port network model of fixed-speed wind turbine generator for distribution system load flow analysis

Load flow analysis has always been used in determining the steady-state operation of an electric power or distribution system. For conventional power system without wind turbine generator, the method for load flow analysis has been well established. However, for modern system embedded with wind turbine generator, the investigation of analysis method is still an active research area. This paper proposed a new method to integrate fixed-speed wind turbine generator into distribution system load flow analysis. The proposed method is derived based on two-port network theory where the parameters of induction generator of the wind turbine generator are embedded in general constants of the two-port network. The proposed method has been tested and verified using a representative electric distribution system.

Performance estimation and analysis of power line communication using single-ended loop testing

Using the electricity infrastructure for broadband data transmission is known as power line communication (PLC). The quality of broadband connectivity over a power line is a strong function of the line topology. Two-step hybrid single-ended loop testing (SELT) to estimate the open port loop topology of power lines is discussed in this paper. Correlation time domain reflectometry (CTDR) at different sockets is used to construct the initial topology. Optimization-based frequency domain reflectometry (FDR) is employed to ascertain more accurate power line topology. The discussed method has the advantage of reusing the existing DSL modem for the measurement and no prior knowledge is needed for the topology estimation. This method is validated for a wide range of line topologies with different numbers of bridge taps. The performance of the estimated topology is calculated using two-port network theory and the influence of the bridge taps on the performance of the line is analyzed.

An Analysis and Optimization on Circuit Characteristics of Non-Contact Wireless Charging System for Electric Vehicles with the TS Resonant Network

The load characteristics of non-contact wireless charging system to electric vehicle are exploited in this paper to improve the output power and transmission efficiency of the system. Firstly, this paper makes a mathematical modeling for the TS-S wireless charging system based on Two-Port Network theory. Then, the features of constant voltage output, output power, and transmission efficiency are discussed later. The results show that TS resonant compensation network could improve the system’s output power, and transmission efficiency. After that, the system’s frequency and load resistance in the optimal working state are calculated. Finally, simulations and experimental results are presented to verify the correctness from theoretical derivations.

Modeling of duct acoustics in the high frequency range using two-ports

Design of duct networks is challenging because the design should consider the required flow rate, acceptable noise levels, and minimum pressure drop to achieve optimum performance. This paper presents acoustic analysis in high frequency range using sound power two-ports applied to Heating, Ventilation, and Air Conditioning (HVAC) systems. To simulate the acoustic behaviour one need to model three mechanisms; the sound power generated from sound sources (e.g. Fans), the regenerated sound power caused by the flow in different elements in the network (e.g. junctions), and the sound power loss across different elements of the network. The general approach considered here is based on two-port theory that divides the duct network into two-port elements. Each element can be described by 2 × 2 scattering matrix where the state variables are the acoustic power flow in both up and downstream directions. Junctions and branching are described by multi-port elements depending on the number of elements connected to this multiport. This algorithm is compared to measurements of HVAC system located in an academic building that shows good agreement. An advantage of this approach is the ability to use the same formalism of the two-port network theory to analyse the acoustic behaviour in both low and high frequency ranges beside the flow distribution and the pressure drop.

Theoretical and experimental study of a wireless power supply system for moving low power devices in ferromagnetic and conductive medium

This paper focuses on the design of a wireless power supply system for low power devices (e.g. sensors) located in harsh electromagnetic environment with ferromagnetic and conductive materials. Such particular environment could be found in linear and rotating actuators. The studied power transfer system is based on the resonant magnetic coupling between a fixed transmitter coil and a moving receiver coil. The technique was utilized successfully for rotary machines. The aim of this paper is to extend the technique to linear actuators. A modeling approach based on 2D Axisymmetric Finite Element model and an electrical lumped model based on the two-port network theory is introduced. The study shows the limitation of the technique to transfer the required power in the presence of ferromagnetic and conductive materials. Parametric and circuit analysis were conducted in order to design a resonant magnetic coupler that ensures good power transfer capability and efficiency. A design methodology is proposed based on this study. Measurements on the prototype show efficiency up to 75% at a linear distance of 20 mm.

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.

Analysis of Millimeter-Wave LC Oscillators Based on Two-Port Network Theory

In this brief, a cross-coupled oscillator is analyzed based on the two-port network theory and the $Y$ - parameter model for a transistor. Contrary to the previous works, the proposed analysis shows that LC cross-coupled oscillators have an additional and higher pure imaginary natural frequency at which the circuit cannot oscillate. The analysis investigates the sufficient condition at which the circuit is able to oscillate at this higher frequency. For the oscillation at the higher frequency mode, we propose adding an extra stage and making a three-stage ring oscillator. The equations obtained from this analysis indicate that the oscillation start-up condition depends on the oscillation frequency. Hence, increasing the speed of the oscillator does not satisfy the start-up condition of oscillators. Our analysis shows that the maximum frequency, in which the circuit stops oscillation in the ring oscillator, is higher than the cross-coupled oscillator and this maximum frequency is very close to the maximum frequency of the transistor.

Parameters Calculations of Transformer and its Performance Analysis under Transients

During this study, a high frequency model of transformer is proposed which is capable of eliminating the effects of transients applied on transformer. The conventional transformers use surge arrestors to remove these kind of effects, but they also transfers the effects of transients on secondary side which are hazardous for electrical equipment’s. Our proposed model is capable of eliminating the effects of transients without any major change in secondary voltage. This method is based on two-port network (T model) theory. The results of our method are examined and evaluated by computer simulations based on MATLAB.

Parameters Calculations of Transformer and its Performance Analysis under Transients

During this study, a high frequency model of transformer is proposed which is capable of eliminating the effects of transients applied on transformer. The conventional transformers use surge arrestors to remove these kind of effects, but they also transfers the effects of transients on secondary side which are hazardous for electrical equipment’s. Our proposed model is capable of eliminating the effects of transients without any major change in secondary voltage. This method is based on two-port network (T model) theory. The results of our method are examined and evaluated by computer simulations based on MATLAB.

Computational Cost Reduction for &lt;italic&gt;N+2&lt;/italic&gt; Order Coupling Matrix Synthesis Based on Desnanot-Jacobi Identity

Matrix inversion is routinely performed in computational engineering, with coupling matrix filter synthesis considered here as just one of many example applications. When calculating the elements of the inverse of a matrix, the determinants of the submatrices are evaluated. The recent mathematical proof of the Desnanot-Jacobi (also known as the “Lewis Carol”) identity shows how the determinant of an N+2 order square matrix can be directly computed from the determinants of the N+1 order principal submatrices and N order core submatrix. For the first time, this identity is applied directly to an electrical engineering problem, simplifying N+2 order coupled matrix filter synthesis (general case, which includes lossy and asymmetrical filters). With the general two-port network theory, we prove the simplification using the Desnanot-Jacobi identity and show that the N+2 coupling matrix can be directly extracted from the zeros of the admittance parameters (given by N+1 order determinants) and poles of the impedance parameters (given by the N order core matrix determinant). The results show that it is possible to decrease the computational complexity (by eliminating redundancy), reduce the associated cost function (by using less iterations), and under certain circumstances obtain different equivalent solutions. Nevertheless, the method also proves its practical usefulness under constrained optimizations when the user desires specific coupling matrix topologies and constrained coefficient values (e.g, purely real/imaginary/positive/negative). This can lead to a direct coupling matrix constrained configuration where other similar methods fail (using the same optimization algorithms).