Sharif Digital Repository

Variable reluctance resolver (VR-Resolver) is a robust electromagnetic sensor that provides position information for closed-loop control systems of permanent magnet synchronous motors (PMSMs). For specific motion control applications, an outer rotor structure is presented for the VR-Resolver in this article with a nonoverlapping tooth-coil windings configuration to simplify the manufacturing process. The study on the structure of the proposed position sensor is carried out, followed by the description of the working principle. The presented outer rotor VR-Resolver is simulated and its performance is investigated in detail with the aid of transient finite-element analysis (TFEA). Sensitivity... 

Since any error in the rotor angle caused by the resolver affects the entire permanent magnet synchronous motor (PMSM) control drive system, it is necessary to investigate its effect on mechanical vibrations. Torsional vibration is accordingly considered in the following study. Thereby, first, the effect of resolver errors on the harmonic content of motor current and, subsequently, torque ripple (TR) was investigated. Then, dynamical modeling is done for the generator-motor-resolver set to get the mechanical frequency response (FR) resulting from the resolver errors. Based on the above modeling, the dynamic equations (DEQs) of the system were derived, and the mechanical characteristics of... 

This paper investigates the influence of residual bow on the stability of a rotating system consisting of an unbalanced Jeffcott rotor with anisotropy and two nonlinear journal bearing supports. The motion equations of the rotor system are formulated and analyzed considering most common faults and features including coupling effects of unbalance, anisotropy and residual shaft bow, by applying Lagrangian dynamics and Floquet theory. Time varying system properties of stiffness and damping are introduced into the equations of motion affecting the rotor behavior, and the influence is studied with respect to the extent of the bearing nonlinearity and the rotor anisotropy. Increasing area of... 

A common solution for increasing the accuracy of wound-rotor (WR) resolvers is to increase the number of poles. To achieve a compact design, fractional slot concentrated winding (FSCW) is used for multi-pole WR resolvers. However, employing such windings leads to rich sub-harmonics in the induced voltages. To suppress these undesirable sub-harmonics, multi-layer windings with an appropriate shifting angle between the layers are suggested. However, the said shifting angle is limited by the slot pitch so that the capability of the multi-layer winding is not utilized fully. To overcome the mentioned deficiency, a slotless disk type configuration is proposed in this article. Then, an... 

In this paper an integrated core, high reliability, linear-rotational resolver with a simple slotless configuration is proposed. The moving part of the proposed resolver has only one helical winding. While, its stator needs at least two individual windings to be able to determine the linear and angular position in simultaneous linear and rotational, helical, motions. Three different configurations are proposed for the stator's windings: (1) helical and horizontally skewed winding (2) helical and vertically skewed winding (3) horizontally and vertically skewed windings. The influence of the mentioned configurations is discussed in the terms of sensor's accuracy in independent and simultaneous... 

In this paper, a novel six-phase outer rotor induction motor equipped with pseudo-concentrated windings is introduced as a robust, reliable, and low-cost solution. Multiple aspects of the proposed motor structure have been investigated such as a design algorithm and an analytical modeling based on the modified winding function considering the skew effect. The effect of using variable number of turns for the coils has been examined on the pseudo-concentrated windings. An appropriate optimization problem has been also defined to maximize the power factor and efficiency and to minimize the output torque ripple. The designed motor has been fabricated to verify the accuracy of the design... 

Two-degree-of-freedom (2-DOF) electrical machines require position sensors for their motion control. In comparison with using two independent sensors, using a 2-DOF sensor enhances the closed-loop control system's performance. However, due to the 3-D structure of the 2-DOF sensor, its performance evaluation needs 3-D analysis. Also, due to helical motion the accuracy deterioration of the sensor, under mechanical faults needs more attention. Although the finite element method (FEM) is the best way to simulate such sensors, most of the commercial packages for transient finite element simulations are not able to consider two separate motions simultaneously. Furthermore, FEM has a high... 

High-efficiency Permanent Magnet Synchronous Motors (PMSMs) are widely used in industry. Subsequently, resolvers' employment is increasing in the drive of PMSMs. Measuring the rotor angle using a resolver needs a costly Resolver to Digital Converter (RDC). Therefore, a low-cost analog RDC is designed against the conventional Angle Tracking Observers (ATOs) in the following study. The designed RDC has satisfactory accuracy, simplicity, and enduring against excitation frequency. Firstly, an overview of the resolver is shown, and subsequently, the circuit of the designed RC is described thoroughly. Ultimately, the simulations' outcomes are displayed, and comparing our design with others... 

This paper proposes a novel design of the variable reluctance permanent magnet (VRPM) resolvers. It utilizes a slotless stator to reduce the resolver volume. The proposed design overcomes the complex structure of windings by replacing them with magnetic flux measurement units (MFMU). The new design eliminates the computationally-expensive demodulation process of output signals by relying on none-modulated signals. An analytical model based on the nonlinear magnetic equivalent circuit (MEC) method is used to extract the output signals of the proposed resolver design. The accuracy of applied analytical model is verified against the time-stepping finite-element method (TSFEM). An optimization... 

The behavior of a Jeffcott rotor with lateral-torsional coupling is investigated in the presence of internal and external damping and eccentricity. The governing equations are derived based on the Lagrange method. Also, the Laplace method and linearization is used to solve the governing equations for free vibrations analysis. For a rotor with unbalance, the instability occurs when the real part of eigenvalues has positive values, and at the same time, it is the intersection point between the lines of natural frequencies. The instability speed increases with increasing the external damping, yet dependent on the internal damping and unbalance. Also, it is demonstrated that the rotor critical... 

High-efficiency Permanent Magnet Synchronous Motors (PMSMs) are widely used in industrial applications. Subsequently, resolvers as position sensors experience increasing usage in the drive of PMSMs. Measuring the rotor's position using a resolver needs a costly Resolver to Digital Converter (RDC). Therefore, in this paper, a software-based, low-cost RDC is presented against the conventional Angle Tracking Observers (ATOs). The proposed RDC is a high-Accuracy two-stage Deep Neural Network (DNN)-based one. In this regard, an overview of the resolvers' function and the general methodology to DNN training is given. Then, the case study is done on the gathered data from the set of the resolver... 

This work studies the nonlinear oscillations of an elastic rotating shaft with acceleration to pass through the critical speeds. A mathematical model incorporating the Von-Karman higher-order deformations in bending is developed and analyzed to investigate the nonlinear dynamics of rotors. A flexible shaft on flexible bearings with springs and dampers is considered as rotor system for the present work. The shaft is modeled as a beam with a circular cross-section and the Euler Bernoulli beam theory is applied. The kinetic and strain energies of the rotor system are derived and Lagrange method is then applied to obtain the coupled nonlinear differential equations of motion for 6° of freedom.... 

This work studies the nonlinear oscillations of an elastic rotating shaft with acceleration to pass through the critical speeds. A mathematical model incorporating the Von-Karman higher-order deformations in bending is developed to investigate the nonlinear dynamics of rotors. A flexible shaft on flexible bearings with springs and dampers is considered as rotor system for this work. The shaft is modeled as a beam and the Euler-Bernoulli beam theory is applied. The kinetic and strain energies of the rotor system are derived and Lagrange method is then applied to obtain the coupled nonlinear differential equations of motion for 6 degrees of freedom. In order to solve these equations... 

Multispeed resolvers are used in the applications that need higher accuracy. However, they suffer from losing absolute position information. To overcome this challenge and improve the reliability of detecting position, the use of multiturn resolvers is recommended. The conventional configuration of multiturn resolver is using two individual resolvers on one shaft and into a common frame. Using such configuration needs special care on setting the distance between two resolvers. In this article, a new structure based on a dual side configuration is proposed. The performance of the double-sided resolver is analyzed and optimized using an analytical model based on a magnetic equivalent circuit.... 

Resolver, as an electromagnetic sensor, is widely used in different industrial applications such as servo motor feedback applications because of its reliable performance in the presence of undesired external factors in a harsh environment. Among different types of resolvers, variable reluctance (VR) resolvers draw attention due to their robust structure with a winding-less solid rotor and low-cost manufacturing. In this article, analytical modeling based on the magnetic equivalent circuit (MEC) is employed to investigate the output signals of the proposed toroidal winding arrangements for VR resolver with a 5-X rotor. Time-stepping finite element analysis (TSFEA) is used for all the... 

In this paper static eccentricity (SE) fault diagnosis in wound rotor (WR) resolver is considered and a new noninvasive index is proposed. Using the proposed index not only leads to SE detection but also, helps to precisely determine the eccentricity level. Furthermore, the location of the fault is determined using two search coils. In this regard, a mathematical model based on the winding function method is proposed. In the proposed model the influence of non-uniform air-gap length on calculating the inductances is considered. Then, time-stepping finite element method (TSFEM) is used for approving the success of the proposed index. Finally, experimental tests are done to validate the... 

The performance of the resolver as a position sensor is significantly influenced by electrical and mechanical faults. Among different faults, short circuit in the stator windings has more destructive effect than others on accuracy of resolver. Furthermore, due to thin wires of the stator it is highly likely to occur. Therefore, in this paper a robust design is proposed for wound-rotor resolvers to not only suppress the influence of short circuit fault in the stator/rotor winding, but also improve the accuracy of the sensor under mechanical faults. The effectiveness of the proposed robust design is demonstrated by an analytical model based on winding function method and then approved by time... 

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... 

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... 

This work studies the nonlinear oscillations of an elastic rotating shaft with acceleration to pass through the critical speeds. A mathematical model incorporating the Von-Karman higher-order deformations in bending is developed and analyzed to investigate the nonlinear dynamics of rotors. A flexible shaft on flexible bearings with springs and dampers is considered as rotor system for the present work. The shaft is modeled as a beam with a circular cross-section and the Euler Bernoulli beam theory is applied. The kinetic and strain energies of the rotor system are derived and Lagrange method is then applied to obtain the coupled nonlinear differential equations of motion for 6° of freedom....