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Farid Tootoonchian - One of the best experts on this subject based on the ideXlab platform.
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A New Variable Reluctance PM-Resolver
IEEE Sensors Journal, 2020Co-Authors: Mahmoud Bahari, Farid Tootoonchian, A. Davoodi, Hamid Saneie, Zahra Nasiri-gheidariAbstract:Resolvers as position sensors need a high frequency AC excitation voltage, and the induced voltage in their 2-phase perpendicular windings are amplitude modulated (AM) signals. For calculating the position, it is required to demodulated the output signals and calculate their envelopes. Then, inverse tangent can be used for calculating the position. Despite the advantages of Resolvers, there are some drawbacks in their application. Calculating the envelopes is always one of the deep concerns in using Resolvers. Furthermore, due to low-amplitude of the excitation flux, the performance of the Resolvers is strongly affected by electromagnetic interference by the stray fields of motor and brake. Complicated winding process is the next challenge of Resolvers. The last concern is referred to the high speed applications where to maintain the accuracy of the sensor it is required to increase the excitation frequency. While, the maximum frequency of excitation is limited by the frequency response of the employed ferromagnetic core and the employed resolver to digital converter (RDC). To overcome all the mentioned worries, a new permanent magnet (PM) resolver is proposed in this paper. The presented resolver has no copper winding and no need to the high frequency excitation. It is equipped by low-price Hall Effect sensors to measure the magnetic flux density and has a robust performance in high electromagnetic disturbance environments. All the analysis is done using time stepping finite element method (TSFEM) and verified by experimental measurements on a built prototype.
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optimal winding selection for wound rotor Resolvers
Scientia Iranica, 2019Co-Authors: Mohammad Mohammadyari, M Safari, Ramin Alipoursarabi, Zahra Nasirigheidari, Farid TootoonchianAbstract:Wound-rotor (WR) Resolvers are the most commercially used Resolvers in industrial applications. In this paper, the effect of different winding arrangements on the accuracy of WR Resolvers is discussed. Three windings are proposed for the stator of the resolver that are involved on-tooth overlapping winding, distributed lap winding and distributed concentric winding. Those windings are also applied to the rotor. All the rotor windings are assumed to be single phase and two-phase. Therefore, the effect of damper winding is also studied in the paper. The analysis is done using time stepping finite element method and the most accurate resolver is built and tested. Close agreement between the experimental measurements and the finite element results confirms the obtained results.
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challenges of finite element analysis of Resolvers
IEEE Transactions on Energy Conversion, 2019Co-Authors: Hamid Saneie, Zahra Nasirigheidari, Ramin Alipoursarabi, Farid TootoonchianAbstract:Nowadays, position sensors are increasingly used in many applications. One of the most commonly used sensors are Resolvers. There are different types of Resolvers including wound rotor Resolvers, variable air-gap length variable reluctance Resolvers, and sinusoidal rotor variable reluctance Resolvers. Regardless of the Resolvers’ configurations, including linear, cylindrical and disk type, finite element analysis (FEA) is inseparable part of design and the performance evaluation of these magnetic sensors. The scope of this study is to discuss challenges in the FEA of Resolvers. The influence of mesh quality, time steps, stop time, excitation methods including voltage source and current source and signal processing methods are investigated in detail. Then, a key question in analysis of Resolvers is answered. The question is Is total harmonic distortion of induced voltages’ envelopes a suitable criterion for the performance evaluation of Resolvers? Finally, four prototypes of different types of Resolvers are used for experimental tests. Good agreements are obtained between simulation and test results indicating the accuracy of following discussions.
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proposal of an analytical model for performance evaluation of wr Resolvers under short circuit fault
Iranian Conference on Electrical Engineering, 2019Co-Authors: Hamed Lasjerdi, Zahra Nasirigheidari, Farid TootoonchianAbstract:Wound-Rotor (WR) Resolvers are the most widely used position sensors in applications with harsh environmental conditions. However, their performance is exposed to failure due to high risk of short circuit (SC) fault. Although the output current of the resolver is negligible, its thin copper wires increases the probability of the short circuit fault. To avoid the propagation of the turn-to turn SC fault to the whole coil and undesirable performance of the motion control drive, it is necessary to diagnose it at the very beginning of its development. Meanwhile, the first step of diagnosing faults is their modeling. Time stepping finite element analysis is the most accurate, but computationally expensive method for modelling the electromagnetic devices. Therefore, it is required to establish an accurate, yet computationally fast model. In this regards, an analytical model based on d-q axes theory is proposed. Then, the success of the proposed model is validated by experimental tests on the studied sensor.
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accuracy improvement in variable reluctance Resolvers
IEEE Transactions on Energy Conversion, 2019Co-Authors: Hamid Saneie, Zahra Nasirigheidari, Farid TootoonchianAbstract:Variable reluctance (VR) Resolvers are widely used in many industrial applications. The conventional winding method for variable air-gap length Resolvers is overlapping, variable turn, on-tooth winding. However, it is not possible to distribute the turn function exactly in accordance with a sinusoidal function. Because, there are a finite number of slots in the stator and only integral number of conductors can be included in each slot. So, in this paper, the influence of rounding off the turn numbers on the accuracy of VR Resolvers is investigated. To minimize that error, an initial angle is defined for the starting of the sinusoidal turn function on the teeth. Meanwhile, the effect of maximum number of turns is studied. It is shown that there is an optimal value for the starting angle of the turn function and the maximum turn numbers to minimize the position error. Furthermore, it is proved that considering the stator slot and rotor pole combinations, there is more than two applicable rotors for a wound stator. All the analysis is verified using time stepping finite element method and experimental tests on a prototype resolver.
Zahra Nasiri-gheidari - One of the best experts on this subject based on the ideXlab platform.
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A New Variable Reluctance PM-Resolver
IEEE Sensors Journal, 2020Co-Authors: Mahmoud Bahari, Farid Tootoonchian, A. Davoodi, Hamid Saneie, Zahra Nasiri-gheidariAbstract:Resolvers as position sensors need a high frequency AC excitation voltage, and the induced voltage in their 2-phase perpendicular windings are amplitude modulated (AM) signals. For calculating the position, it is required to demodulated the output signals and calculate their envelopes. Then, inverse tangent can be used for calculating the position. Despite the advantages of Resolvers, there are some drawbacks in their application. Calculating the envelopes is always one of the deep concerns in using Resolvers. Furthermore, due to low-amplitude of the excitation flux, the performance of the Resolvers is strongly affected by electromagnetic interference by the stray fields of motor and brake. Complicated winding process is the next challenge of Resolvers. The last concern is referred to the high speed applications where to maintain the accuracy of the sensor it is required to increase the excitation frequency. While, the maximum frequency of excitation is limited by the frequency response of the employed ferromagnetic core and the employed resolver to digital converter (RDC). To overcome all the mentioned worries, a new permanent magnet (PM) resolver is proposed in this paper. The presented resolver has no copper winding and no need to the high frequency excitation. It is equipped by low-price Hall Effect sensors to measure the magnetic flux density and has a robust performance in high electromagnetic disturbance environments. All the analysis is done using time stepping finite element method (TSFEM) and verified by experimental measurements on a built prototype.
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Longitudinal End Effect in a Variable Area Linear Resolver and its Compensating Methods
Electrical Engineering (ICEE) Iranian Conference on, 2018Co-Authors: Mahmoud Bahari, Zahra Nasiri-gheidariAbstract:Linear permanent magnet machines are increasingly used in industrial applications where they need position sensors to improve their performance. Variable Reluctance Resolvers are one the best position sensors that can be used in unfriendly environment conditions, with high mechanical vibration, wide temperature variation and polluted environments. However, conventional VR Resolvers suffer from complicated winding process, undesirable performance under eccentricities, and high position error in two-pole applications. So, in this paper a new linear resolver is proposed based on the sinusoidal variation of common area between the moving and the stationary parts. Then, the influence of longitudinal end effect on the accuracy of the sensor is discussed and finally three compensating methods are proposed. All the simulations are done using 3-D time stepping finite element analysis (3-D TSFEA). Then, the out signals are imported into Matlab in order to calculate the position error.
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Linearized Resolver
2018Co-Authors: Ramin Alipour-sarabi, Farid Tootoonchian, Zahra Nasiri-gheidari, Ashknaz Oraee, Fateme ZareAbstract:Resolvers are used in position estimation systems. These electromagnetic sensors, take the benefits of electrical machines. In comparison with encoders, they are robust and more reliable. However, their accuracy is questioned when one of the output voltages is in the peak position. In these situation the other signal is about zero. Therefore, the rate of signal to noise is too low and more susceptible to be affected from environmental disturbances. To overcome this inefficiency, a new winding scheme is suggested in this paper. The proposed winding arrangement that is carried out on a disk type variable reluctance resolver has its own merits: compact size, fault tolerate capability, high accuracy and easy to manufacture. Finite element analysis verify the analytical expressions. Finally, a prototype of proposed resolver is fabricated. Both the finite element analysis and experimental results confirms the excellence of new winding configuration over the custom one.
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Design, Performance Analysis, and Prototyping of Linear Resolvers
IEEE Transactions on Energy Conversion, 2017Co-Authors: Zahra Nasiri-gheidariAbstract:Linear position sensors are widely used in linear motion-control systems. In this paper, the design, optimization, performance analysis, and prototyping of a linear resolver (LR) are discussed. Mathematical model of the proposed structure is presented based on a simple, design-oriented method. Then, a comprehensive iterative design algorithm considering design constraints of linear electromagnetic sensors is proposed. All resistances and inductances of the designed LR are calculated based on the design parameters. Then, 3D time-stepping finite-element method (3D TSFEM) is used to validate the design, optimization, and analytical model. Finally, a prototype of the sensor is built and tested. Comparison between the results of simulation and experimental tests verified the success of the proposed structure.
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Twelve-slot two-saliency variable reluctance resolver with non-overlapping signal windings and axial flux excitation
IET Electric Power Applications, 2017Co-Authors: Farid Tootoonchian, Zahra Nasiri-gheidariAbstract:© The Institution of Engineering and Technology 2016. In this study, a new 12-slot two-saliency variable reluctance (VR) resolver with simple non-overlapping windings is proposed. The excitation winding in the proposed resolver is replaced with one axial coil that is perpendicular to the signal windings. Both distributed and non-overlapping concentric windings with uniform coil turns are used. The rotor has two upper and lower saliencies located in front of each other. The shape and width of each saliency are determined based on the optimisation. Compared with conventional 12-slot VR Resolvers, the proposed resolver has a simpler rotor structure and the advantages of two-saliency Resolvers against eccentricity, absolute output position, and higher accuracy. The operation principle of the proposed resolver is analytically shown. Then, a three-dimensional time-stepping finite-element method (FEM) is used for the design, analysis, and optimisation of the proposed sensor. After optimisation, a prototype of the most accurate resolver is built. The good agreement obtained between the FEM and the practical results verifies the design and optimisation process.
Zahra Nasirigheidari - One of the best experts on this subject based on the ideXlab platform.
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optimal winding selection for wound rotor Resolvers
Scientia Iranica, 2019Co-Authors: Mohammad Mohammadyari, M Safari, Ramin Alipoursarabi, Zahra Nasirigheidari, Farid TootoonchianAbstract:Wound-rotor (WR) Resolvers are the most commercially used Resolvers in industrial applications. In this paper, the effect of different winding arrangements on the accuracy of WR Resolvers is discussed. Three windings are proposed for the stator of the resolver that are involved on-tooth overlapping winding, distributed lap winding and distributed concentric winding. Those windings are also applied to the rotor. All the rotor windings are assumed to be single phase and two-phase. Therefore, the effect of damper winding is also studied in the paper. The analysis is done using time stepping finite element method and the most accurate resolver is built and tested. Close agreement between the experimental measurements and the finite element results confirms the obtained results.
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challenges of finite element analysis of Resolvers
IEEE Transactions on Energy Conversion, 2019Co-Authors: Hamid Saneie, Zahra Nasirigheidari, Ramin Alipoursarabi, Farid TootoonchianAbstract:Nowadays, position sensors are increasingly used in many applications. One of the most commonly used sensors are Resolvers. There are different types of Resolvers including wound rotor Resolvers, variable air-gap length variable reluctance Resolvers, and sinusoidal rotor variable reluctance Resolvers. Regardless of the Resolvers’ configurations, including linear, cylindrical and disk type, finite element analysis (FEA) is inseparable part of design and the performance evaluation of these magnetic sensors. The scope of this study is to discuss challenges in the FEA of Resolvers. The influence of mesh quality, time steps, stop time, excitation methods including voltage source and current source and signal processing methods are investigated in detail. Then, a key question in analysis of Resolvers is answered. The question is Is total harmonic distortion of induced voltages’ envelopes a suitable criterion for the performance evaluation of Resolvers? Finally, four prototypes of different types of Resolvers are used for experimental tests. Good agreements are obtained between simulation and test results indicating the accuracy of following discussions.
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proposal of an analytical model for performance evaluation of wr Resolvers under short circuit fault
Iranian Conference on Electrical Engineering, 2019Co-Authors: Hamed Lasjerdi, Zahra Nasirigheidari, Farid TootoonchianAbstract:Wound-Rotor (WR) Resolvers are the most widely used position sensors in applications with harsh environmental conditions. However, their performance is exposed to failure due to high risk of short circuit (SC) fault. Although the output current of the resolver is negligible, its thin copper wires increases the probability of the short circuit fault. To avoid the propagation of the turn-to turn SC fault to the whole coil and undesirable performance of the motion control drive, it is necessary to diagnose it at the very beginning of its development. Meanwhile, the first step of diagnosing faults is their modeling. Time stepping finite element analysis is the most accurate, but computationally expensive method for modelling the electromagnetic devices. Therefore, it is required to establish an accurate, yet computationally fast model. In this regards, an analytical model based on d-q axes theory is proposed. Then, the success of the proposed model is validated by experimental tests on the studied sensor.
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accuracy improvement in variable reluctance Resolvers
IEEE Transactions on Energy Conversion, 2019Co-Authors: Hamid Saneie, Zahra Nasirigheidari, Farid TootoonchianAbstract:Variable reluctance (VR) Resolvers are widely used in many industrial applications. The conventional winding method for variable air-gap length Resolvers is overlapping, variable turn, on-tooth winding. However, it is not possible to distribute the turn function exactly in accordance with a sinusoidal function. Because, there are a finite number of slots in the stator and only integral number of conductors can be included in each slot. So, in this paper, the influence of rounding off the turn numbers on the accuracy of VR Resolvers is investigated. To minimize that error, an initial angle is defined for the starting of the sinusoidal turn function on the teeth. Meanwhile, the effect of maximum number of turns is studied. It is shown that there is an optimal value for the starting angle of the turn function and the maximum turn numbers to minimize the position error. Furthermore, it is proved that considering the stator slot and rotor pole combinations, there is more than two applicable rotors for a wound stator. All the analysis is verified using time stepping finite element method and experimental tests on a prototype resolver.
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design considerations of multi turn wound rotor Resolvers
International Conference on Power Electronics and Drive Systems, 2019Co-Authors: S Hajmohammadi, Zahra Nasirigheidari, Ramin Alipoursarabi, Farid TootoonchianAbstract:Multi-turn Resolvers are consisted of two individual Resolvers in one housing. Due to use of both single speed and multi-speed Resolvers in one frame, multi-turn Resolvers are supposed to provide the benefits of higher accuracy and absolute position measurement, simultaneously. In this paper, after presenting different configurations of wound-rotor (WR), multi-turn Resolvers, their design considerations are discussed. Winding function (WF) method is used for finding appropriate slot-pole combinations, and winding configurations. Then time stepping finite element analysis is applied to evaluate the performance of the designed Resolvers. Finally, experimental measurements validate the simulation results.
Nael Abu-ghazaleh - One of the best experts on this subject based on the ideXlab platform.
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INFOCOM - Collaborative Client-Side DNS Cache Poisoning Attack
IEEE INFOCOM 2019 - IEEE Conference on Computer Communications, 2019Co-Authors: Fatemah Alharbi, Zhiyun Qian, Jie Chang, Feng Qian, Yuchen Zhou, Nael Abu-ghazalehAbstract:DNS poisoning attacks inject malicious entries into the DNS resolution system, allowing an attacker to redirect clients to malicious servers. These attacks typically target a DNS resolver allowing attackers to poison a DNS entry for all machines that use the compromised resolver. However, recent defenses can effectively protect Resolvers rendering classical DNS poisoning attacks ineffective. In this paper, we present a new class of DNS poisoning attacks targeting the client-side DNS cache. The attack initiates DNS poisoning on the client cache, which is used in all main stream operating systems to improve DNS performance, circumventing defenses targeting Resolvers. Our attack allows an off-path attacker to collaborate with a piece of an unprivileged malware to poison the OS-wide DNS cache on a client machine. We developed the attack on Windows, Mac OS, and Ubuntu Linux. Interestingly, the behaviors of the three operating systems are distinct and the vulnerabilities require different strategies to exploit. We also generalize the attack to work even when the client is behind a Network Address Translation (NAT) router. Our results show that we can reliably inject malicious DNS mappings, with on average, an order of tens of seconds. Finally, we propose a defense against this type of poisoning attacks.
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Collaborative Client-Side DNS Cache Poisoning Attack
IEEE INFOCOM 2019 - IEEE Conference on Computer Communications, 2019Co-Authors: Fatemah Alharbi, Zhiyun Qian, Jie Chang, Feng Qian, Yuchen Zhou, Nael Abu-ghazalehAbstract:DNS poisoning attacks inject malicious entries into the DNS resolution system, allowing an attacker to redirect clients to malicious servers. These attacks typically target a DNS resolver allowing attackers to poison a DNS entry for all machines that use the compromised resolver. However, recent defenses can effectively protect Resolvers rendering classical DNS poisoning attacks ineffective. In this paper, we present a new class of DNS poisoning attacks targeting the client-side DNS cache. The attack initiates DNS poisoning on the client cache, which is used in all main stream operating systems to improve DNS performance, circumventing defenses targeting Resolvers. Our attack allows an off-path attacker to collaborate with a piece of an unprivileged malware to poison the OS-wide DNS cache on a client machine. We developed the attack on Windows, Mac OS, and Ubuntu Linux. Interestingly, the behaviors of the three operating systems are distinct and the vulnerabilities require different strategies to exploit. We also generalize the attack to work even when the client is behind a Network Address Translation (NAT) router. Our results show that we can reliably inject malicious DNS mappings, with on average, an order of tens of seconds. Finally, we propose a defense against this type of poisoning attacks.
Gao Wenxue - One of the best experts on this subject based on the ideXlab platform.
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error analysis and compensation of multipole Resolvers
Measurement Science and Technology, 1999Co-Authors: Liu Mingji, Yao Yu, Zou Jibin, Lu Yongping, Ngoo Livingstone, Gao WenxueAbstract:The signal errors of the multipole resolver and the measurement error incurred due to the signal errors are analysed, and expressions for the errors are determined. Based on the results of the analysis, a compensation method utilizing an analogue circuit for the measurement error is presented. The zero-position error and the amplitude error of the 34-pole resolver are compensated using the compensation circuit presented. The measurement accuracy of the 34-pole resolver is improved significantly from about 15 to 2 min. The correctness of the analysis result and the effectiveness of the compensation method are also verified.
