• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.142-149
• /
• 2011

This paper presents a new state of charge(SOC) estimation of large capacity of Li-ion battery (LIB) based on the multiple model adaptive estimation(MMAE) method. We first introduce an equivalent circuit model of LIB. The relationship between the terminal voltage and the open circuit voltage(OCV) is nonlinear and may vary depending on the changes of temperature and C-rate. In this paper, such behaviors are described as a set of multiple linear time invariant impedance models. Each model is identified at a temperature and a C-rate. These model set must be obtained a priori for a given LIB. It is shown that most of impedances can be modeled by first-order and second-order transfer functions. For the real time estimation, we transform the continuous time models into difference equations. Subsequently, we construct the model banks in the manner that each bank consists of four adjacent models. When an operating point of cell temperature and current is given, the corresponding model bank is directly determined so that it is included in the interval generated by four operating points of the model bank. The MMAE of SOC at an arbitrary operating point (T $^{\circ}C$, $I_{bat}$[A]) is performed by calculating a linear combination of voltage drops, which are obtained by four models of the selected model bank. The demonstration of the proposed method is shown through simulations using DUALFOIL.

• Journal of Magnetics
• /
• v.17 no.1
• /
• pp.19-26
• /
• 2012

This paper deals with the performance analysis and estimation of the electrical parameters of a permanent magnet synchronous generator (PMSG) for hydrokinetic energy conversion applications using vortex induced vibration (VIV). The analytical solutions for the magnetic fields produced by permanent magnets (PMs) and stator winding currents are obtained using a 2D polar coordinate system and a magnetic vector potential. An analytical expression for the 2D permeance is also derived, which takes into account stator skew effects. Based on these magnetic field solutions and the 2D permeance function, electrical circuit parameters such as the backemf constant and the air-gap inductance are obtained analytically. The performances of the PMSG are investigated using the estimated electrical circuit parameters and an equivalent circuit (EC). All analytical results are validated extensively using 2D finite element (FE) analyses. Experimental measurements for parameters such as the back-emf and inductance are also presented to confirm the analyses.

• Transactions on Electrical and Electronic Materials
• /
• v.17 no.1
• /
• pp.13-17
• /
• 2016

The ampere-hour integral method and the open circuit voltage method are integrated via the extended Kalman filter method so as to overcome insufficiencies of the ampere-hour integral method and the open circuit voltage method for estimating battery SOC. The process noise covariance and the measurement noise covariance of the extended Kalman filter method are simplified based on the Thevenin equivalent circuit model, with a proposed simplified SOC estimating method. Verification of DST experiments indicated that the battery SOC estimating method is simple and feasible, and the estimated SOC error is no larger than 2%.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.345-348
• /
• 2000

변환기의 해석 및 선계에 있어서 측정되어진 데이터로부터 그 변환기의 진기, 기계, 음향적인 특성변수를 추출하는 기술의 확보는 설계되어진 변환기의 검증 및 최적화를 위해서 필수적이다. 이와 관련한 기존의 방법은 측정방법이 번거롭고 그 결과 또한 많은 오차를 포함하고 있는 관계로 변환기의 정확한 특성변수를 추출하는데 어려움이 많았다. 본 연구에서는 전기음향변환기의 정확한 특성변수 추출을 위하여 기존의 방법과는 달리 Levy Method 반복적으로 사용하여 그 오차를 최소화하는 알고리듬을 개발하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.891-895
• /
• 2004

This paper suggests the techniques in determining the values of the steady-state equivalent circuit parameters of a three-phase squirrel-cage induction machine using immune algorithm. The parameter estimation procedure is based on the steady state phase current versus slip and input power versus slip characteristics. The proposed estimation algorithm is of a nonlinear kind based on clonal selection in immune algorithm. The machine parameters are obtained as the solution of a minimization of least-squares cost function by immune algorithm. Simulation shows better results than the conventional approaches.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.8
• /
• pp.1406-1415
• /
• 2010

As process technology for semiconductor goes beyond the ultra-deep submicrometer regime, interconnect reliability on a chip has become a serious design concern. As process parameters scale, interconnect widths are reduced rapidly while the current flowing through the interconnect does not decrease in a proportional manner. This trend increases current densities in metal interconnects which may lead to poor reliability for electromigration. Hence, it is critical to estimate the current amount passing through the interconnects earlier in semiconductor design stages. The purpose of this paper is to propose a fast yet accurate current estimation technique that can offer not only analysis time equivalent to those offered by the previous approximation methods but also a relatively precise estimation by using closed-form equations. The accuracy of the proposed technique was confirmed to be about 8 times better on average when compared to the previous work.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2004.10a
• /
• pp.21-25
• /
• 2004

This paper suggests the techniques in determining the values of the steady-state equivalent circuit parameters of a three-phase squirrel-cage induction machine using immune algorithm. The parameter estimation procedure is based on the steady state phase current versus slip and input power versus slip characteristics. The proposed estimation algorithm is of a nonlinear kind based on clonal selection in immune algorithm. The machine parameters are obtained as the solution of a minimization of least-squares cost function by immune algorithm. Simulation shows better results than the conventional approaches.

• Journal of Power Electronics
• /
• v.16 no.5
• /
• pp.1981-1989
• /
• 2016

Battery diagnosis is vital to battery-based applications because it ensures system reliability by avoiding battery failure. This paper presents a novel intelligent battery charger with an online diagnosis function to circumvent interruptions in system operation. The charger operates in normal charging and diagnosing modes. The diagnosis function is performed with the impedance spectroscopy technique, which is achieved by injecting a sinusoidal voltage excitation signal to the battery terminals without the need for additional hardware. The impedance spectrum of the battery is calculated based on voltage excitation and current response with the aid of an embedded digital lock in amplifier in a digital signal processor. The measured impedance data are utilized in the application of the complex nonlinear least squares method to extract the battery parameters of the equivalent circuit. These parameters are then compared with the reference values to reach a diagnosis. A prototype of the proposed charger is applied to four valve-regulated lead-acid batteries to measure AC impedance. The results are discussed.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.237-239
• /
• 2018

This paper proposes an on-line estimation algorithm of internal resistance of Li-ion battery based on the recursive least squares method to prevent the overvoltage and undervoltage casing degradation of life cycle of battery. An equivalent circuit model with single time constant is adopted, and under assumptions that the terminal voltage, current and SOC are measured accurately, the discrete time based nonlinear equation of the model can be converted to the linear equation which can be applied to recursive least squares method. Since the coefficients of the discrete time linear equation can be expressed by the parameters of the equivalent circuit model, it is shown that an internal resistance (Ri) can be estimated in real time using the least square method.

• Progress in Superconductivity and Cryogenics
• /
• v.23 no.4
• /
• pp.44-48
• /
• 2021

In order to obtain ultra-high resolution MRI images, research and development of 11 T or higher superconducting magnets have been actively conducted in the world, recently. The high-temperature superconductor (HTS), first discovered in 1986, was very limited in industrial application until mid-2010, despite its high critical current characteristics in the high magnetic field compared to the low-temperature superconductor. This is because HTS magnets were unable to operate stably due to the thermal damage when a quench occurred. With the introduction of no-insulation (NI) HTS magnet winding technology that does not burn electrically, it could be expected that the HTS magnets are dramatically reduced in weight, volume, and cost. In this paper, a 6 T-class NI HTS magnet for basic characteristic analysis was designed, and a distributed equivalent circuit model of the NI coils was configured to analyze the charging current characteristics caused by excitation current, and the charge delay phenomenon and loss were predicted through the development of a simulation model. Additionally, the critical current of the NI HTS magnets was estimated, considering the magnetic field, its angle and temperature with a given current. The loss due to charging delay characteristics was analyzed and the result was shown. It is meaningful to obtain detailed operation technology to secure a stable operation protocol for a 6T NI HTS magnet which is actually manufactured.