Comparison of High Frequency Square Wave and Sinusoidal Wave Signal Injection Methods for IPMSM Sensorless Drive Application

Ahmadreza Alaei(라쉬디),Dong-Hee Lee(이동희),Jin-Woo Ahn(안진우),Sayed Morteza Saghaeian Nejad(세헤이안) 대한전기학회 2017 대한전기학회 학술대회 논문집 Vol.2017 No.7

Inverse Scattering of Two-Dimensional Objects Using Linear Sampling Method and Adjoint Sensitivity Analysis

Ahmadreza Eskandari,Mohammad Reza Eskandari 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

This paper describes a technique for complete identification of a two-dimensional scattering object and multiple objects immersed in air using microwaves where the scatterers are assumed to be a homogenous dielectric medium. The employed technique consists of initially retrieving the shape and position of the scattering object using a linear sampling method and then determining the electric permittivity and conductivity of the scatterer using adjoint sensitivity analysis. Incident waves are assumed to be TM (Transverse Magnetic) plane waves. This inversion algorithm results in high computational speed and efficiency, and it can be generalized for any scatterer structure. Also, this method is robust with respect to noise. The numerical results clearly show that this hybrid approach provides accurate reconstructions of various objects.

Sensorless Control of IPMSM with a Simplified High-Frequency Square Wave Injection Method

Ahmadreza Alaei,Dong-Hee Lee,Jin-Woo Ahn,Sayed Morteza Saghaeian Nejad 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

This paper presents a sensorless speed control of IPMSM (Interior Permanent Magnet Synchronous Motor) using the high-frequency (HF) square wave injection method. In the proposed HF pulsating square wave injection method, injection voltage is applied into the estimated d-axis of rotor and high-frequency induced q-axis current is considered to estimate the rotor position. Conventional square wave injection methods may need complex demodulation process to find rotor position, while in the proposed method, an easy demodulation process based on the rising-falling edge of the injected voltage and carrier induced q-axis current is implemented, which needs less processing time and improves control bandwidth. Unlike some saliency-based sensorless methods, the proposed method uses maximum torque per ampere (MTPA) strategy, instead of zero d-axis command current strategy, to improve control performance. Furthermore, this paper directly uses resultant d-axis current to detect the magnet polarity and eliminates the need to add an extra pulse injection for magnet polarity detection. As experimental results show, the proposed method can quickly find initial rotor position and MTPA strategy helps to improve the control performance. The effectiveness of the proposed method and all theoretical concepts are verified by mathematical equations, simulation, and experimental tests.

Effect of Gradation Curve and Dry Density on Collapse Deformation Behavior of a Rockfill Material

Ahmadreza Tabibnejad,Ali Akbar Heshmati,Hossein Salehzadeh,Saeed Hashemi Tabatabaei 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.3

Rockfill material, such as other coarse grained materials, undergoes rapid or sudden settlements of relatively large values, withoutany changes in the applied loads and only because of submerging. In the literature this phenomenon is called collapse deformation. The effects of gradation curve and dry density on the collapse deformation behavior of a rockfill material were explored and thechanges in the strength and deformability parameters of this material caused by submerging were determined. Two large scale triaxialequipments with three different sample diameters of 20, 30 and 80 cm were employed and a set of dry-saturated tests wereconducted. Specimens with different gradation curves and various initial dry densities were tested. The results indicate that in all ofthe dry-saturated tests, sudden reductions in the shear strengths and volumes of the specimens were observed during the submergingprocess. The effects of material maximum particle size, fines content and initial dry density on the value of sudden shear strengthreduction, internal friction angle reduction caused by saturation (Δφc), the change in elasticity modulus of the material due tosubmerging, i.e., (Ewet/Edry), and also the saturation-induced sudden volumetric strain (εvc) were evaluated and discussed.

Comparisons of The High Frequency Signal Injection Algorithms for PMSM Sensorless Drive

Ahmadreza Alaei(알라이),Dong-Hee Lee(이동희),Jin-Woo Ahn(안진우),Sayed Morteza Saghaeian Nejad(세헤이안) 대한전기학회 2017 대한전기학회 학술대회 논문집 Vol.2017 No.4

In this paper, comparison of HF signal injection algorithms for PMSM sensorless drive and some design considerations on these methods is presented. The most famous methods, i.e. HF rotating injection in the stationary reference frame and pulsating injection in the estimated synchronous reference frame are compared. Some advantages and disadvantages of these methods as well as some problems affecting on sensorless algorithm performance such as phase delay in demodulation process, time delay due to the PWM unit and A/D converter, the effect of voltage amplitude and frequency of injected signal will be explained. All the Mathematical equation and concepts of theory are simulated and validated by MATLAB/SIMULINK software.

Assess the Effectiveness of SMA on Response of Steel Connection with PT Strands

Ahmadreza Torabipour,Azam Abdollahi,Shaghayegh Yaghoubi 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.12

Using the post-tensioned (PT) elements can significantly plummet the persistent damages and the relevant costs to post-earthquake repair and maintenance, facing earthquake hazards. Rooted in a PT self-centering steel connection, the deformation and residual drift of the main members are limited to the linear elastic branch derived from existence of steel strands by omitting the gap between beam-column connections. The shape memory alloys (SMA) material has super elastic property according to the conversion of austenite to martensite phases due to changes in the temperature and stress. In this research, a nonlinear behavior of PT steel connection with top-and-seat angles was analyzed due to vulnerability of the connection during the cyclic loading, so that the connection was equipped with stiffened angles and SMA material in order to improve seismic behavior of the steel connection. The results illustrated that the using the equipped angles with SMA property flourish a logical performance in the steel connection under cyclic loading, by which the connection witnesses an appropriate energy dissipation (ED) capacity and dramatically effect on initial stiffness.

Full-state-feedback, Fuzzy type I and Fuzzy type II control of MEMS accelerometer

Ahmadreza Najafi,Jafar Keighobadi 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.2

This paper presents classic and knowledge-based intelligent controllers for regulation of a vibratory MEMS accelerometer. The proposed methods comprise Fuzzy type I (FTI), Fuzzy type II (FTII) and Full-state-feedback (FSF) control systems. An ideal model of sensor under FSF controller is used to generate the required reference data to train if-then rule-base and Membership functions (MFs) of both fuzzy controllers. Through feeding the reference data as well as the FTI/FTII output into an Adaptive neural fuzzy inference system (ANFIS), the rules and MFs of the FTI/FTII system are updated. The control systems are realized by adding a Kalman filter (KF) loop to the force-balancing method for estimation of state variables and input acceleration. Stochastic noises are filtered out while keeping good tracking performance of MEMS accelerometer and reducing the displacement of the mass under the closed-loop ANFIS-KF structure.

Optimum Design of Integer and Fractional-Order PID Controllers for Boost Converter Using SPEA Look-up Tables

Ahmadreza Amirahmadi,Mohammadreza Rafiei,Kambiz Tehrani,Giovanni Griva,Issa Batarseh 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

This paper presents a method of designing optimal integer- and fractional-order proportional?integral-derivative (FOPID) controllers for a boost converter to gain a set of favorable characteristics at various operating points. A Pareto-based multi-objective optimization approach called strength Pareto evolutionary algorithm (SPEA) is used to obtain fast and low overshoot start-up and dynamic responses and switching stability. The optimization approach generates a set of optimal gains called Pareto set, which corresponds to a Pareto front. The Pareto front is a set of optimal results for objective functions. These results provide designers with a trade-off look-up table, in which they can easily choose any of the optimal gains based on design requirements. The SPEA also overcomes the difficulties of tuning the FOPID controller, which is an extension to the classic integer-order PID controllers and potentially promises better results. The proposed optimized FOPID controller provides an excellent start-up response and the desired dynamic response. This paper presents a detailed comparison of the optimum integer- and the fractional-order PID controllers. Extensive simulation and experimental results prove the superiority of the proposed design methodology to achieve a wide set of desired technical goals.

Optimal Controller Design for Single-Phase PFC Rectifiers Using SPEA Multi-Objective Optimization

Ahmadreza Amirahmadi,Ali Dastfan,Mohammadreza Rafiei 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

In this paper a new method for the design of a simple PI controller is presented and it has been applied in the control of a Boost based PFC rectifier. The Strength Pareto evolutionary algorithm, which is based on the Pareto Optimality concept, used in Game theory literature is implemented as a multi-objective optimization approach to gain a good transient response and a high quality input current. In the proposed method, the input current harmonics and the dynamic response have been assumed as objective functions, while the PI controller’"s gains of the PFC rectifier (Kpi, Tpi) are design variables. The proposed algorithm generates a set of optimal gains called a Pareto Set corresponding to a Pareto Front, which is a set of optimal results for the objective functions. All of the Pareto Front points are optimum, but according to the design priority objective function, each one can be selected. Simulation and experimental results are presented to prove the superiority of the proposed design methodology over other methods.

Bedside-Friendly Prediction for Presence of Post-Myocardial lnfarction Systolic Dysfunction Using Multimarker Panel: Integrating Salivary Diagnostics into Clinical Practice

Ahmadreza Assareh,Habib Haybar,Hojjat Yoosefi,Mohammadreza Bozorgmanesh 대한심장학회 2013 Korean Circulation Journal Vol.43 No.4

Background and Objectives: We investigated if a combination of plasma or salivary interleukin-2 (IL-2), interleukin-6 (IL-6), tumor necro-sis factor-alpha (TNF-α), transforming growth factor-beta (TGF-β), and troponin can improve estimation of the pretest probability of the left ventricular systolic dysfunction (LVSD). Subjects and Methods: Eighty patients with newly-diagnosed myocardial infarction (MI) were echocardiographically examined for LVSD (ejection fraction ≤40%). Measurements included traditional MI risk factors, plasma and salivary concentrations of troponin, IL-2, IL-6,TNF-α, and TGF-β. With the LVSD as the outcome variable, we developed logistic regression models, starting with a basic model incorpo-rating traditional risk factors and consecutively adding salivary and plasma biomarkers. Models were compared using several criteria, in-cluding (but not limited to) C statistic (discrimination) and net reclassification improvement index (NRI). Results: Apart from troponin, plasma, and salivary values of the biomarkers were correlated: spearman’s ρ was 0.19 (p=0.088) for troponin,0.36 (p=0.001) for IL-2, 0.74 (p<0.001) for IL-6, 0.61 (p<0.001) for TNF-α, and 0.65 (p<0.001) for TGF-β. The predictive performances of the basic model for estimating the pretest probability of the presence of LVSD considerably improved when cytokines were added (salivary added: C-statistic from 0.77 to 0.82 and NRI 77%; plasma added: C-statistic to 0.80 and NRI 134%). Conclusion: Multiple biomarkers added diagnostic value to the standard risk factors for predicting the presence of post-MI LVSD.