Sharif Digital Repository

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.... 

Single-phase, outer-rotor squirrel cage induction motors are widely used in ceiling fan applications. Furthermore, they can be employed for pumps, and in-wheel hub drives. In this article, an analytical model based on magnetic equivalent circuit is proposed to evaluate the performance of the motor. The influence of rotor slots' skewing, stator end windings, slots' leakage inductance, and core saturation are included in the model. Furthermore, the windings' copper losses and the core's iron losses are calculated using the proposed model. The results of the presented model are compared with those of time variant finite element analysis (TVFEA) and experimental measurements close agreement... 

Variable Reluctance (VR) resolver is an angular position sensor that is commonly used in the automotive industry. In this paper, A general method for determining the winding configuration of VR resolvers is proposed, that eases the manufacturing process. At first, the operational principle of conventional winding has been presented using mathematical formulations. Following that, the non-overlapping tooth coil winding method, as the ideal winding option for VR resolver, has been extended that can be applied to the VR resolver with arbitrary poles and stator tooth numbers. The method of determining the reference and signal windings presented and used to determine the winding for a 2, 6, and 8... 

Variable reluctance (VR) resolver is an angular position sensor, which is commonly used in the automotive industry. In this article, a general method for determining the winding configuration of VR resolvers is proposed, which eases the manufacturing process. At first, the operational principle of conventional winding has been presented using mathematical formulations. Following that, the nonoverlapping tooth coil winding method, as the ideal winding option for VR resolver, has been extended, which can be applied to the VR resolver with arbitrary poles and stator tooth numbers. The method of determining the reference and signal windings presented and used to determine the winding for a two,... 

In this study an analytical model based on solving Maxwell equations in the machine layers is presented for linear resolver (LR). Anisotropy, field harmonics, slot effects, number of slots per pole per phase and the effect of tooth skewing are considered in the model. The proposed method is a design oriented technique that can be used for performance prediction and design optimisation of the LR due to its acceptable accuracy and fast computation time. Two- and three-dimensional time stepping finite element method (FEM) is employed to validate the results of the proposed model. Good correlations between the results obtained by the proposed method and the FEM confirm the superiority of the... 

Using linear position sensors is necessary in linear motion control systems. In this paper the influence of winding's pole pairs on the accuracy of linear resolver is studied. 2-D and 3-D time stepping finite element method (FEM) is used to calculate the performance characteristics of the resolver. The effect of finite mover's length, transverse edge effect and the end windings length are discussed in detail. Then a prototype of the studied resolver along with its experimental test setup is built. Good correlation between simulation and experimental results verified the simulation process. © 2017 IEEE  

Axial flux variable reluctance (AFVR) resolvers have substantial benefits that make them suitable for motion control drives. However, they suffer from insufficient accuracy, especially in high-accuracy applications. Hence, optimizing the AFVR resolver structure is necessary for improving its commercial usage. However, its accurate modelling needs three-dimensional (3-D) time stepping finite element analysis (TSFEA) that is computationally expensive and unsuitable for co-usage with optimization algorithms. The aim of this paper is to establish an accurate, yet computationally fast, model suitable for optimal design of AFVR resolvers. The working of the proposed model is based on magnetic... 

Cost, durability and reliability are three critical issues in electrical/hybrid electrical vehicles (EV/HEV). In this regard, resolvers are often used as position and speed sensors in such applications. In this paper design and analysis of a novel multi-turn resolver is discussed to address all the mentioned issues. The proposed resolver has got one stator core and one rotor core. Double sets of signal windings on the stator and a special excitation winding on the rotor are designed to achieve both absolute and multi-speed operations. Mathematical model of the proposed resolver is verified using time stepping finite element analysis and experimental measurements. © 1967-2012 IEEE  

Multi-turn resolvers are employed in the applications that high reliability; high accuracy and absolute position measurement are required, simultaneously. They are basically consisted of two individual resolvers in a common frame. In this paper a novel sinusoidal air-gap length multi-turn resolver is proposed. The rotor shape and the winding configuration are designed to achieve single-speed and multi-speed operations using a single rotor and a single stator core. Furthermore, some constraints are laid down and discussed in such a way that the performance of two resolvers has no interference with each other. All the mathematical calculations are validated using time stepping finite element... 

In this article, field-reconstruction method (FRM) is proposed for predicting the performance of different types of rotational resolvers, including wound-rotor (WR) and variable reluctance (VR) ones. The main features of the developed method are comparable accuracy with that of the finite element method (FEM) as well as much less computational burden. The deviation of the developed model in the prediction of position error of WR and VR resolvers is less than 3%. However, the computational burden of the proposed method for different type of resolvers is from 30 up to 150 times less than that of FEM. Accordingly, the proposed model can be used for the design and optimization of different... 

Winding configuration is a crucial factor that highly affects the accuracy of resolvers. A nonoptimal winding could also make the manufacturing process complicated and costly inefficient. In this article, an approach to determine the optimal winding configuration for the resolvers is proposed. This method is applicable for both wound rotor (WR) and variable reluctance (VR) resolvers, and significantly simplifies the winding configuration of resolvers with different pole pairs and teeth numbers. Based on the proposed approach, the winding configuration of multiturn resolvers, which are generally more complicated than single-turn resolvers, is simplified for WR and VR type resolver with... 

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 (WR) resolvers, Variable Air-gap Length Variable Reluctance (VAGL-VR) resolvers, and Sinusoidal Rotor Variable Reluctance (SR-VR) resolvers. Regardless of the resolvers’ configurations, including linear, cylindrical and disk type, finite element analysis (FEA) is inseparable part of design and 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 volt-age... 

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... 

Four 5-, 10-, 20- and 30-story moment frames, representing low-, mid-, and two high-rise structures, were subjected to a great number of idealized directivity pulses. The amplitudes and periods of pulses vary from 0.02 g to 1.0 g and 0.5 to 12 sec, respectively. Over 1400 nonlinear dynamic analyses of low- to high-rise moment frames were performed which were feasible through using modified fish-bone model. The distribution of interstory drift along the height was studied and two applied contours were proposed: (i) the maximum interstory drift contour, and (ii) the critical story contour. These contours were demonstrated versus the ratio of natural period of the structure to the pulse period... 

In this article singular points of a parallel manipulator are obtained based on a novel geometrical method. Here we introduce the constrained plain method (CPM) and some of its application in parallel mechanism. Given the definition of constraint plane (CP) and infinite constraint plane (ICP) the dependency conditions of constraints is achieved with the use of a new theorem based on the Ceva geometrical theorem. The direction of angular velocity of a body is achieved by having three ICPs with the use of another theorem. Finally, with the use of the above two novel theorems singularities of the 3UPF_PU mechanism are obtained. It should be emphasized that this method is completely geometrical,... 

An analytical model is proposed to study the effect of particle size on melting enthalpy and entropy of metallic nanoparticles (NPs). The Mott's and Regel's equations for melting entropy in the combination of core average coordination number (CAC) and surface average coordination number (SAC) of freestanding NPs are considered. Clusters of icosahedral (IC), body centered cubic (BCC), and body centered tetragonal (BCT) structure without any vacancies and defects are modeled. Using the variable coordination number made this model to be in good agreement with experimental and molecular dynamic (MD) results of different crystal structures. The model predicts melting entropy and enthalpy of... 

Grinding is widely used for manufacturing of components that require fine surface finish and good dimensional accuracy. In this study a thermo-mechanical finite element analysis is conducted to find out how grinding parameters can affect temperature and residual stress distribution in the workpiece. Results of parametric study presented in this work indicate, by carefully selecting the grinding parameters, minimum thermal and mechanical damage can be achieved. Higher workpiece velocities produce higher surface residual stress. By increasing depths of cut, depth of tensile residual stresses increases. Convection heat coefficient does not have any considerable effect on surface residual stress... 

Adaptive Noise Cancellation (ANC) is a well-known technique for background noise reduction in automobile and vehicular environments. The noise fields in automobile and other vehicle interior obey the diffuse noise field model closely. On the other hand, the ANC does not provide sufficient noise reduction in the diffuse noise fields. In this paper, a new multistage post-filter is designed for ANC as a solution to diffuse noise conditions. The designed post-filter is a single channel Linear Prediction (LP) based speech enhancement system. The LP is performed by an adaptive lattice filter and attempts to extract speech components by using intermediate ANC signals. The post-filter has no...