Design, Analysis, and Equivalent Circuit Modeling of Dual Band PIFA Using a Stub for Performance Enhancement

Hojin Jung,Kwangho Kim,Wansoo Nah,Jawad Yousaf 한국전자파학회JEES 2016 Journal of Electromagnetic Engineering and Science Vol.16 No.3

This work presents a new method for enhancing the performance of a dual band Planer Inverted-F Antenna (PIFA) and its lumped equivalent circuit formulation. The performance of a PIFA in terms of return loss, bandwidth, gain, and efficiency is improved with the addition of the proposed open stub in the radiating element of the PIFA without disturbing the operating resonance frequencies of the antenna. In specific cases, various simulated and fabricated PIFA models illustrate that the return loss, bandwidth, gain, and efficiency values of antennas with longer optimum open stub lengths can be enhanced up to 4.6 dB, 17%, 1.8 dBi, and 12.4% respectively, when compared with models that do not have open stubs. The proposed open stub is small and does not interfere with the surrounding active modules; therefore, this method is extremely attractive from a practical implementation point of view. The second presented work is a simple procedure for the development of a lumped equivalent circuit model of a dual band PIFA using the rational approximation of its frequency domain response. In this method, the PIFA’s measured frequency response is approximated to a rational function using a vector fitting technique and then electrical circuit parameters are extracted from it. The measured results show good agreement with the electrical circuit results. A correlation study between circuit elements and physical open stub lengths in various antenna models is also discussed in detail; this information could be useful for the enhancement of the performance of a PIFA as well as for its systematic design. The computed radiated power obtained using the electrical model is in agreement with the radiated power results obtained through the full wave electromagnetic simulations of the antenna models. The presented approach offers the advantage of saving computation time for full wave EM simulations. In addition, the electrical circuit depicting almost perfect characteristics for return loss and radiated power can be shared with antenna users without sharing the actual antenna structure in cases involving confidentiality limitations.

Modeling and Analysis of the Fractional Order Buck Converter in DCM Operation by using Fractional Calculus and the Circuit-Averaging Technique

Faqiang Wang,Xikui Ma 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6

By using fractional calculus and the circuit-averaging technique, the modeling and analysis of a Buck converter with fractional order inductor and fractional order capacitor in discontinuous conduction mode (DCM) operations is investigated in this study. The equivalent averaged circuit model of the fractional order Buck converter in DCM operations is established. DC analysis is conducted by using the derived DC equivalent circuit model. The transfer functions from the input voltage to the output voltage, the duty cycle to the output voltage, the input impedance, and the output impedance of the fractional order Buck converter in DCM operations are derived from the corresponding AC-equivalent circuit model. Results show that the DC equilibrium point, voltage ratio, and all derived transfer functions of the fractional order Buck converter in DCM operations are affected by the inductor order and/or capacitor order. The fractional order inductor and fractional order capacitor are designed, and PSIM simulations are performed to confirm the correctness of the derivations and theoretical analysis.

Circuit Model for the Effect of Nonradiative Recombination in a High-Speed Distributed-Feedback Laser

Bowen Nie,Zhijuan Chi,Qing-an Ding,Xiang Li,Changqing Liu,Xiaojuan Wang,Lijun Zhang,Juan Song,Chaofan Li 한국광학회 2020 Current Optics and Photonics Vol.4 No.5

Based on single-mode rate equations, we present an improved equivalent-circuit model for distributedfeedback (DFB) lasers that accounts for the effects of parasitic parameters and nonradiative recombination. This equivalent-circuit model is composed of a parasitic circuit, an electrical circuit, an optical circuit, and a phase circuit, modeling the circuit equations transformed from the rate equations. The validity of the proposed circuit model is verified by comparing simulation results to measured results in the literature. The results show that the slope efficiency and threshold current of the model are 0.22 W/A and 13 mA respectively. It is also shown that increasing bias current results in the increase of the relaxation-oscillation frequency. Moreover, we show that the larger the bias current, the lower the frequency chirp, increasing the possibility of extending the transmission distance of an optical-fiber communication system. The results indicate that the proposed circuit model can accurately predict a DFB laser’s static and dynamic characteristics.

Equivalent circuit model of a rectangular RF driven hydrogen ion source for impedance matching network design

Huh, Sung-Ryul,Park, Min,Jung, Bong-Ki,Chang, Doo-Hee,Kim, Tae-Seong,Kim, Sun-Ho,Jeong, Seung Ho Elsevier 2018 Fusion engineering and design Vol.136 No.2

<P><B>Abstract</B></P> <P>KAERI is presently developing a rectangular RF driven deuterium ion source for both neutron source and fusion applications. For a model-based design of a reliable impedance matching network for the ion source, we extend an equivalent circuit model of the ion source system by allowing effects of an isolation transformer and a Faraday shield on the system to be reflected in our previous model (Huh et al., 2017 <I>Fusion Eng. Des.</I> <B>121</B> 337). In this paper we use the model to investigate the trends in external electrical characteristics of the ion source system (e.g., voltage and current across and through an RF antenna coil and the impedance matching network circuit components) with RF power of up to 50 kW. The model results provide criteria for the impedance matching network design and data for an assessment of the ion source performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An equivalent circuit model of a rectangular radio frequency driven hydrogen ion source is developed. </LI> <LI> This model predicts electrical characteristics of the ion source equipped with an isolation transformer and a Faraday shield. </LI> <LI> The model is used to design of an impedance matching network for the KAERI rectangular radio frequency driven ion source. </LI> </UL> </P>

광대역유도분극 이상 자료의 해석을 위한 새로운 등가회로 모델

신승욱 ( Seung Wook Shin ),박삼규 ( Samg Yu Park ),신동복 ( Dong Bok Shin ) 한국지구물리·물리탐사학회 2014 지구물리와 물리탐사 Vol.17 No.4

Spectral induced polarization (SIP) is a useful technique, which uses electrochemical properties, for explorationof metallic sulfide minerals. Equivalent circuit analysis is commonly conducted to calculate IP parameters from SIP data. An equivalent circuit model, which indicates the SIP response of rock, has a non-uniqueness problem. For this reason,it is very important to select the proper model for accurate analysis. Thus, this study focused on suggesting a new model,which suitable for the analysis of an anomalous SIP response, such as ore. A suitability of the new model was verifiedby comparing it with the existing Dias model and Cole-Cole models. Analysis errors were represented as a normalizedroot mean square error (NRMSE). The analysis result using the Dias model was the NRMSE of 10.50% and was theNRMSE using the Cole-Cole model of 17.03%. Howerver, because the NRMSE of the new model is 0.87%, it isconsidered that the new model is more useful for analyzing the anomalous SIP data than other models.

An Equivalent Circuit Model for a Dumbbell-Shaped DGS Microstrip Line

Taek-Kyung Lee,Duk-Jae Woo 한국전자파학회JEES 2014 Journal of Electromagnetic Engineering and Science Vol.14 No.4

This paper presents an equivalent circuit model for a dumbbell-shaped defected ground structure (DGS) in a microstrip line. The effects of equivalent circuit elements of a dumbbell-shaped DGS and their magnetic coupling to the host transmission line are modeled as a simple lumped-element circuit. In addition, simple approximate expressions to determine the main circuit parameters for this model are presented. The transfer characteristic calculated by the proposed circuit model is compared with the results of EM simulation and measurement.

Study on Joint Simulation of Very Fast Transient Overvoltage and Transient Enclosure Voltage in 1000 kV GIS

Zhang Yan-Ze,Chen Xiao-Yue,Si Jun-Jie,He Ze-Yu,Wen Xi-Shan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

Disconnector operation in GIS generates VFTO and TEV, which threaten device insulation and personnel safety. In order to calculate VFTO and TEV more accurately, this paper proposes a VFTO-TEV joint simulation model. Among them, dynamic arc model is used to reflect the dynamic characteristics of high frequency AC arc. In order to reflect the electromagnetic leakage phenomenon caused by the impedance mismatch of high-frequency electromagnetic waves, and the influence of the transient potential difference formed by the transient electromagnetic field on grounding grid on TEV, the geometric structures of high-voltage bushing, grounding pillars and grounding grid are modeled to obtain their respective frequency-dependent admittance matrices, which are converted into corresponding broadband equivalent circuit models by combining vector fitting method and impedance synthesis method. The above modeling method is applied to the 1000 kV GIS test circuit, and the simulation model is built in the ATP-EMTP electromagnetic transient program, and the joint simulation research of VFTO and TEV is carried out. The results show that at each measurement point of the test circuit, the amplitude error of the VFTO obtained by simulation and actual measurement is mostly less than 7%, and the frequency spectrum both contains the main frequency components of 18 MHz and 25 MHz; Compared with the traditional calculation model of obtaining VFTO/TEV using CIGRE model/Petersen's law, the amplitude of VFTO and TEV obtained by joint simulation model is lower and contains richer high-frequency components. In addition, the opening speed of 0.8 m/s also corresponds to the maximum point of the VFTO amplitude of the test circuit. Finally, based on the above modeling method, the effectiveness of adding ferrite beads to suppress VFTO is verified by simulation. © 2017 Elsevier Inc. All rights reserved.

Equivalent-circuit Analysis of ITO/Alq3/AlOrganic Light-emitting Diode

Dong-Hoe Chung,Tae Wan Kim 한국전기전자재료학회 2007 Transactions on Electrical and Electronic Material Vol.8 No.3

An ITO/Alq3/Al structure was used to study complex impedance of Alq3 based organic light-emitting diodes. Equivalent circuit was analyzed in a device structure of ITO/Alq3/Al with a thickness layer of Alq3 of 100 nm. The obtained impedance was able to be fitted using equivalent circuit model of parallel combination of resistance Rp and capacitance Cp with a small series resistance of Rs.

Small-Size Induction Machine Equivalent Circuit Including Variable Stray Load and Iron Losses

Mateo Ba?i?,Dinko Vukadinovi? 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

The paper presents the equivalent circuit of an induction machine (IM) model which includes fundamental stray load and iron losses. The corresponding equivalent resistances are introduced and modeled as variable with respect to the stator frequency and flux. Their computation does not require any tests apart from those imposed by international standards, nor does it involve IM constructional details. In addition, by the convenient positioning of these resistances within the proposed equivalent circuit, the order of the conventional IM model is preserved, thus restraining the inevitable increase of the computational complexity. In this way, a compromise is achieved between the complexity of the analyzed phenomena on the one hand and the model’s practicability on the other. The proposed model has been experimentally verified using four IMs of different efficiency class and rotor cage material, all rated 1.5 kW. Besides enabling a quantitative insight into the impact of the stray load and iron losses on the operation of mains-supplied and vector-controlled IMs, the proposed model offers an opportunity to develop advanced vector control algorithms since vector control is based on the fundamental harmonic component of IM variables.

Equivalent hysteresis model based SOC estimation with variable parameters considering temperature

He, Yao,Li, Qiang,Zheng, Xinxin,Liu, Xintian The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3

Estimation of the state of charge (SOC) of a lithium-ion battery is one of the key technologies in battery management systems. The accuracy of SOC estimation mainly depends on the accuracy of the battery model. The traditional Thevenin model has limited application due to its fixed parameters. In addition, its accuracy is not high. This paper proposes a variable parameter equivalent hysteresis model based on the Thevenin model. The parameters of this model are regarded as variables that vary with temperature and SOC. They can be identified by hybrid pulse power characteristic (HPPC) experiments. In addition, the model also considers the hysteresis characteristics of the open circuit voltage (OCV) and uses a mathematical recursive equation to describe it. Experimental and simulation results show that the proposed model has a higher accuracy and a wider application than the Thevenin model. On the basis of this model, SOC estimation is carried out based on modified covariance extended Kalman filter (MVEKF) at different temperatures. The results show that the SOC estimation accuracy of the MVEKF method is significantly higher than that of an extended Kalman filter (EKF).