Online Embedded Impedance Measurement Using High-Power Battery Charger

Yong-Duk Lee,Sung-Yeul Park,Soo-Bin Han IEEE 2015 IEEE transactions on industry applications Vol.51 No.1

<P>This paper presents a new functionality for high-power battery chargers by incorporating an impedance measurement algorithm. The measurement of battery impedance can be performed by the battery charger to provide an accurate equivalent model for battery management purposes. In this paper, an extended control capability of the onboard battery charger for electric vehicles is used to measure the online impedance of the battery. The impedance of the battery is measured by the following: 1) injecting ac current ripple on top of the dc charging current; 2) transforming voltage and current signals using a virtual α-β stationary coordinate system, a d-q rotating coordinate system, and two filtering systems; 3) calculating ripple voltage and current values; and 4) calculating the angle and magnitude of the impedance. The contributions of this paper are the use of the d-q transformation to attain the battery impedance, theta, and its ripple power, as well as providing a controller design procedure which has impedance measurement capability. The online impedance information can be utilized for diverse applications such as the following: 1) a theta control for sinusoidal current charging; 2) the quantifying of reactive current and voltage; 3) ascertaining the state of charge; 4) determining the state of health; and 5) finding the optimized charging current. Therefore, the benefit of this method is that it can be deployed in already existing high-power chargers regardless of battery chemistry. Validations of the proposed approach were made by comparing measurement values by using a battery charger and a commercial frequency response analyzer.</P>

다채널 미세전극칩 임피던스 분석을 위한 자동 스위칭 시스템: 한계점 및 개선 방안

이석영,남윤기,Lee, Seok-Young,Nam, Yoon-Key 대한의용생체공학회 2011 의공학회지 Vol.32 No.3

Electrode impedances are measured to quantitatively characterize the electrode-electrolyte or cell-electrode interfaces. In the case of high-density microelectrode arrays(MEAs) that have been developed for brainmachine interface applications, the characterization process becomes a repeating and time-consuming task; a system that can perform the measurement and analysis in an automated fashion with accuracy and speed is required. However, due to the large number of channels, parasitic capacitance and off-capacitance components of the switching system become the major factors that decreased the accuracy for the measurement of high impedance microelectrodes. Here we investigated the implementation of automatic impedance measurement system with analyzing the causes of possible measurement-related problems in multichannel switching configuration. Based on our multi-channel measurement circuit model, we suggest solutions to the problems and introduce a novel impedance measurement scheme using electro-mechanical relays. The implemented measurement system could measure |Z| < 700 $k{\Omega}$ of impedance in - 10% errors, which can be widely applicable to high density neural recording MEAs.

A Novel Impedance Measurement Method for Three-Phase Power Electronic Systems

Qingyu Dou,Zeng Liu,Jinjun Liu,Weihan Bao 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Power electronic systems could be unstable due to the interaction between converters. Impedance-based stability analysis is an effective approach to predict stability and to provide design criteria. Therefore significant are impedance measurement techniques, which have been well established for DC systems, but need to be improved for AC systems nevertheless. This paper proposes a novel AC impedance measurement method which injects bipolar pulse at current zero-crossing point. Compared with existing methods, it enhances accuracy and reduces distortion. Simulation and experimental results demonstrate the effectiveness of the novel method.

Design and Implementation of Novel Impedance Measurement using Digital Sine-wave Oscillator with Optimum Phase and Amplitude

Sukanya Praesomboon,Thitaphan Jongsataporn,Surapun Yimman,Fusak Cheevasuvit 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

This paper proposed the AC bridge circuit, which can be used to measure unidentified impedance of the system. The AC bridge circuit takes the advance of both a digital sine-wave oscillator, which can promptly adjust the phase of generated signals, and a successive approximation technique, which can profoundly search for the unknown impedance. Therefore, the optimum phase and the suitable amplitude can be immediately determined for the AC bridge circuit. In this study, the unknown impedance were calculated by the AC bridge circuit at these following frequencies 50Hz, 100Hz, 300Hz, 500Hz, 750Hz and 1kHz. When compared with the LCR meter (Agilent 4284A), the result of the measured impedance from the AC bridge circuit has revealed the impedance with estimate 1% average error, which suggested that AC bridge circuit is a perfectly innovation method for identifying the unknown impedance.

Improvement of electrical blood hematocrit measurements under various plasma conditions using a novel hematocrit estimation parameter

Kim, Myounggon,Kim, Ayoung,Kim, Sohee,Yang, Sung Elsevier 2012 Biosensors & bioelectronics Vol.35 No.1

<P><B>Abstract</B></P> <P>This paper presents an electrical method for measurement of Hematocrit (HCT) using a novel HCT estimation parameter. Particularly in the case of electrical HCT measurements, the measurement error generally increases with changes in the electrical conditions of the plasma such as conductivity and osmolality. This is because the electrical properties of blood are a function not only of HCT, but also of the electrical conditions in the plasma. In an attempt to reduce the measurement errors, we herein propose a novel HCT estimation parameter reflecting the characteristics of both the changes in volume of red blood cells (RBCs) and electrical conditions of plasma, simultaneously. In order to characterize the proposed methods under various electrical conditions of plasma, we prepared twelve blood samples such as four kinds of plasma conditions (hypotonic, isotonic, two kinds of hypertonic conditions) at three different HCT levels. Using linear regression analysis, we confirmed that the proposed parameter was highly correlated with reference HCT (HCT<SUB>ref.</SUB>) values measured by microcentrifugation. Thus, the HCT measurement error was less than 4%, despite considerable variations in the conductivity and osmolality of the plasma at conditions of the HCT<SUB>ref.</SUB> of 20%. Multiple linear regression analysis showed that the proposed HCT estimation parameter also yielded a lower measurement error (1%) than the other parameter previously used for the same purpose. Thus, these preliminary results suggest that proposed method could be used for accurate, fast, easy, and reproducible HCT measurements in medical procedures.</P> <P><B>Highlights</B></P> <P>▸ We propose an electrical measurement method of blood hematocrit (HCT) within a 3D type measurement cell based on a novel parameter. ▸ The proposed parameter is independent of the electrical conditions (conductivity, osmolality) of blood plasma and this method dramatically reduces (<1%) a HCT measurement error compared with the ones previous reported electrical HCT measurement methods (2.5–16.3%). ▸ Thus we believe that the demonstrated method in this paper is promising one for accurate, fast, easy, and reproducible HCT measurements.</P>

High Precision On-Line Impedance Measurement for a Li-Ion battery

S M Rakiul Islam,Sung-Yeul Park 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents a highly precise battery impedance measurement algorithm. The proposed algorithm consists of fast Fourier transformations, peak, and phase difference estimations. Additional offset clipping and amplifying circuits expand the range of the signal measurement. An opamp based offset clipping circuit increases the ac ripple to DC voltage ratio without phase delay. Amplifying circuit gives more resolution to the ripple voltage. These proposed instrumentation ensure the precise measurement of ripple voltage and current. The proposed algorithm determines the peak magnitude of ripple voltage with tolerance of 0.12mV, and the phase difference tolerance is 0.2%. To validate the proposed approach, a 40Ah 13.6V Li-Ion battery charger was built using a Opal-RT controller, a synchronous buck converter, and offset clipping and amplifying circuits.

A Handheld Electronics Module for Dielectrophoretic Impedance Measurement of Cancerous Cells in the Microchip

Ngoc-Viet Nguyen,Jih-Hao Yeh,Chun-Ping Jen 한국바이오칩학회 2018 BioChip Journal Vol.12 No.3

This study proposes a handheld electronics module integrated with the microchip that utilizes dielectrophoretic (DEP) impedance measurement for characterizing of cancerous cell lines. The microchip consists of circle-on-line-shaped interdigitated microelectrodes, which were used for DEP concentration and impedance sensing of cells within a chamber, patterned by standard microfabrication processes. The handheld electronics module was built for measuring impedance of cancerous cells in the microchip. It can provide sinusoidal electrical signals in a large range of frequencies. The analyzed results demonstrate a high-sensitivity impedance measurement. Meanwhile, the linear relationships between the admittance variation and the number of cell were observed for both two human lung cell lines, namely A549 human lung carcinoma cells and MRC-5 human lung epithelial cells. The difference in the slopes of these characteristic lines could be used to distinguish two stages of lung cells. The proposed device is simple to operate, has high sensitivity, inexpensive and portable.

A method for in-situ measurement of grid impedance and load impedance at 2 k – 150 kHz

Junzhe Tan,Dongsheng Zhao,Braham Ferreira 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

A new approach to measure the grid and load impedance of converters in-situ at frequency range 2 k ? 150 kHz has been developed. It is called three-probe approach. This approach allows impedance measurements of power supplies and electric appliances without interrupting their normal operations. The measurement accuracy is improved by proper Fast Fourier Transform (FFT) process to obtain both amplitude and phase information in the measurement. With the proposed setup, the equivalent model consisting of both resistive and reactive components can be derived to represent the grid and load in this frequency range. Grid impedance at different locations and load impedance of various solid state lamps and a SMPS are measured and the results are shown in the paper.

유도 가열 시스템의 실시간 임피던스 계측을 통한 용기의 온도 추정 기법

정지훈,김현지,허경욱 대한전기학회 2022 전기학회논문지 Vol.71 No.9

Recently, induction heating (IH) technologies are widely applied in home cooking appliances due to characteristics such as fast heating, energy-saving, and high efficiency. In the IH systems, load impedance variations depend on switching frequency, pot material, operating temperature, and alignment between the pot and the induction coil. The pot’s temperature estimation using the impedance measurement of the resonant network can be used to improve the efficiency of the IH system and to make the IH cooking safe without additional temperature sensors. In this paper, a time-split method is proposed to measure a real-time impedance and to estimate the pot’s temperature by using the regression model of the impedance. The proposed temperature estimation technique is verified using a 2-kW series resonant inverter prototype.

Wind farm resonance characteristics analysis based on harmonic impedance measurement method

Yang, Yude,Yuan, Lili,Qin, Zhijun,Liu, Hui The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.4

Recently, subsynchronous oscillation (SSO) has been captured in direct-drive permanent magnetic synchronous generator (PMSG) based wind farms in many areas without series compensation in nearby power grids. However, there are fewer reports related to this new type of SSO. In addition, an analysis of the new SSO based on existing methods is computationally cumbersome, and the control effect of the converter was generally simplified in previous studies, which lead to serious errors. This paper proposes a method for analyzing the resonance characteristics of wind farms based on impedance measurement to simplify calculations and improve accuracy. The correctness and effectiveness of the proposed method are validated through the IEEE first benchmark model. A time-domain simulation model of a direct-drive PMSG is established and analyzed by harmonic impedance measurement. The results show that SSO exists when direct-drive PMSGs are connected to a weak AC system. The converter of the direct-drive PMSG exhibits a small negative value at the oscillation mode frequency. This means that the converter behaves like a capacitor with negative impedance. The capacitive impedance of the converter forms a resonant loop with the inductance of the AC grid and causes unstable SSO.