This thesis is comprehensively dedicated to the theoretical and experimental reevaluation of the Synchronous Reluctance Machine (SynRM). A simple approach to derive the SynRM main characteristics and behavior is followed. An introduction to an evaluation of the different control strategies in is given. Finding suitable rotor geometry for the SynRM has been a subject for major investigation since 1923. This thesis will investigate the interior barrier rotor structure of the SynRM using the Finite Element Method (FEM) based sensitivity analysis. The Permanent Magnet assisted SynRM (PMaSynRM) is studied. The main aim here is to address accurately, qualitatively and quantitatively the main characteristics of such a machine. A heat-run test has been done on a prototyped SynRM and its corresponding IM and Interior Permanent Magnet (IPM) Machine to investigate the potential of the SynRM, under variable speed drive (VSD) supply conditions. This gives the state-ofart based on these measurements on the prototype SynRM and benchmarks its performance. The main behavior and characteristics of an anisotropic structure, suitable for high performance SynRM rotor geometry design, is distinguished and discussed. The carefully selected general rotor shape and some optimum distribution rules are used to develop a novel FEM-aided fast rotor design optimization for SynRM. Torque ripple minimization of SynRM is discussed. This is done by the development of a general method that minimizes the ripple independent of the stator structure. The torque ripple and interconnection to iron losses are briefly discussed. Based on these design tools, a design that is a compromise between the final machine?s performance and simplicity of the rotor structure is studied as the improved machine design. The fine tuned most promising design is prototyped and its performance compared with IM. Naturally, to have an anisotropic structure the q-axis flux must be blocked and simultaneously the d-axis flux must flow smoothly. One possibility is to align the barrier edges along the d-axis natural flux lines in the solid rotor. A prototype of the final optimized machine design SynRM is manufactured. The performance of this machine is measured and compared with the improved machine design. The effect of the number of poles on SynRM performance is discussed. Some of the most important secondary effects in SynRM are studied. Skew and torque quality, the possible effects of alternative voltage or current source supplies on torque and iron losses, the start-up and short-circuit locked rotor tests performed on the standard IM and the prototype SynRM and the effect of eccentricity are investigated. An overview comparison between IM and SynRM is given. For this purpose, a high performance rotor structure for SynRM with standard sizes of 3kW, 15kW and 90kW is designed. The thermal performance of the SynRM is discussed by analyzing the measured machine temperatures. A detailed picture regarding the thermal performance of the SynRM machine is presented. A full scale performance evaluation of the SynRM in comparison to its counterpart the IM is given. All IM and SynRM motors have the same standard stator for each size. The MTPA control strategy is used. Finally, all reported measurements in this thesis are summarized and analyzed.

Synchronous Reluctance Machine (SynRM) in Variable Speed Drives (VSD) Applications

In the paper, a space-vector pulsewidth-modulation (SVPWM) inverter is proposed for constant-power operation of a two-phase induction motor. The operating principle of SVPWM is described, and the algorithm for constant-power operation is presented. Analysis for dynamic operation using a simple scalar control scheme is carried out and parameters for implementation of the scheme are obtained. Experimental investigation of the scheme is carried out and comparative analysis of the performance of the scheme is presented.

Space-vector Modulation in a two-phase induction motor drive for constant-power operation

The growth of electric and hybrid electric vehicles has drawn more attention toward the development of high power density electrical machines. The materials used in the fabrication of electrical machines play a crucial role in enhancing their power density. In this paper, the significance of advanced magnetic materials for lamination, nano-material based conducting materials, and high energy product permanent magnets (PMs) is discussed in detail. Finally, a case study has been presented with a 5 kW PM synchronous machine in order to understand the advantages of the discussed materials.

High Power Density Electrical Machines for Electric Vehicles—Comprehensive Review Based on Material Technology

For a reliable dynamic system and significant amount of savings in energy usage, adjustable speed drives (ASD) can play a vital role. The proper control of motor drives can give a good system response and also increase the efficacy of the drive. Recently the direct torque control (DTC) strategy has drawn great attention for motor drives due to its simplicity, insensitivity to the motor parameters, high reliability and improved dynamic response. Many control strategies have been developed for the improvement of conventional DTC drives focusing specifically on torque and flux. A number of techniques have been formulated and successfully implemented for induction motor (IM) control. This paper aims to provide a substantial updated review, albeit by no means complete, for those who are interested in keeping track of the present state-of-the-art in this field and working further. The review focuses on different control algorithms of DTC IM drives and their applications to minimize the energy losses and improve the system efficacy.

A review of reliable and energy efficient direct torque controlled induction motor drives

The first and the most important step in solving the environmental problems created by cars with internal combustion engines is research and development of electric vehicles. Selection of a proper drive and optimal control strategy of electric vehicles are the major factors to obtain optimal energy management in order to extend the running distance per battery charge. This paper presents a brief review of direct torque control (DTC) of induction motors (IM) as well as its implementation for electric vehicle (EV) applications. First, the basic DTC technique based on hysteresis controllers will be introduced, and then an overview of the major problems in a basic DTC scheme will be presented and explained, as well as some efforts for improving the technique. The main section presents a critical review of DTC for EV applications, taking into consideration the vehicle mechanics and aerodynamics of electric vehicles. The review is very important to provide guidelines and insights for future research and development on the DTC of IM drives for sustainable reliability and energy efficient EV applications.

A review of direct torque control of induction motors for sustainable reliability and energy efficient drives

This paper presents two new rotor configurations for the line start permanent-magnet synchronous motors (PMSMs). The first configuration proposed here uses inset consequent magnet pole arrangement with double cage, and results into improved starting performance when compared to the other rotor configurations previously used. The second configuration proposed uses a combination of circumferentially and radially magnetized magnets (hybrid rotor), with induced magnet poles, which results into improved synchronous performance. Two-dimensional finite-element analysis has been employed in the analysis of transient and steady-state performances. The experimental prototypes for the second configuration are built and tested extensively. To demonstrate the effectiveness of the hybrid rotor configuration, an additional prototype is made that employs the circumferentially magnetized magnets (spoke magnet type rotor), and performance of the proposed rotor is benchmarked with this. Analysis, simulation, and experimental results indicate that the proposed rotor configuration leads to improved steady-state performance, by utilizing 10% less magnet volume than the benchmarked spoke rotor. The proposed configurations are also suitable for inverter-fed brushless dc, and PMSMs.

Rotor Configurations for Improved Starting and Synchronous Performance of Line Start Permanent-Magnet Synchronous Motor

In this study, wide overview of the existing line start permanent magnet synchronous motors literature is presented. The treatment of the subject has been effectively sub-divided in to five sections; (i) rotor topologies and design, (ii) steady state analysis, (iii) transient state analysis, (iv) parameter estimation and (v) high efficiency standards. Although, there are numerous papers published in each category, only those important papers which have made significant contributions in the developments and thus triggered research in this field are discussed here.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-epa.2013.0241

Overview of research evolution in the field of line start permanent magnet synchronous motors

This study presents a rotor structure, for a line start permanent magnet synchronous motors (LSPMSMs), which can be applied to other types of inverter driven motors, such as brushless dc and permanent magnet synchronous motors. In this development, the magnet configuration is a combination of both circumferentially (spoke) as well as radially magnetised (embedded) magnets which are so arranged that induced poles are generated in alternate positions in the heteropolar structure, thereby reducing the quantity of permanent magnets in the rotor. Both the transient as well as steady-state performances of the machine have been analysed by using time-stepping finite element method. For experimental demonstration a prototype which uses spoke magnets (P1), plus two prototypes (P2 and P3) of the proposed magnet arrangement have been built. The former (P1) is used for benchmarking the performance of the proposed configuration. Results have indicated that the rotor configuration reported here (P2) with reduced magnet volume gives better performance than the spoke magnet rotor LSPMSM. Also, the performances of prototype LSPMSMs are compared with that of the standard induction motor of the same frame size and physical dimensions.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-epa.2013.0223

Induced pole rotor structure for line start permanent magnet synchronous motors

In this work, an Artificial Neural Network (ANN) is developed to improve the performance of Space Vector Modulation (SVM) based Direct Torque Controlled (DTC) Induction Motor (IM) drive. The ANN control algorithm based on Scaled Conjugate Gradient (SCG) method is developed. The algorithm is tested on MATLAB Simulink platform. Results show smooth steady state operation as well as fast and dynamic transient performance. This is due to the SCG training algorithm of ANN which has the benchmarked performance against the standard Back-propagation (BP) algorithm. BP uses gradient descent optimization theory which has user selected parameters; learning rate and momentum constant. The network is trained offline and has fixed parameters. This leads to extra control effort and demands for online tuning of the parameters. SCG algorithm tunes these parameters with the use of second order approximation. Additionally, it takes less learning iterations and hence results in faster learning. Robustness to parameter variations and disturbances is the basic advantage of ANN, thus effectively controlling inherently non linear IM.

https://hal.inria.fr/hal-01557626/document

Scaled Conjugate Gradient Based Adaptive ANN Control for SVM-DTC Induction Motor Drive

This paper presents the design of Direct Torque Controlled (DTC) Induction Motor drive that incorporates Artificial Neural Network (ANN) based controller. The control algorithms are employed to improve control performance, and to reduce torque and flux ripple. A new control strategy for Space Vector Modulation based DTC (SVM_DTC) using ANN to generate control vector is proposed. The paper investigates application of ANN to Conventional DTC (C_DTC) and SVM_ DTC. Simulation studies show that the intelligent control technique is able to reduce the torque and flux ripples and to improve the performance of the drive especially at low speed. Proposed ANN_SVM_DTC is less complex, requires a single ANN controller for decoupled torque and flux control, and improves the performance.

B. N. Chaudhari

Papers

Rotor Configurations for Improved Starting and Synchronous Performance of Line Start Permanent-Magnet Synchronous Motor

Overview of research evolution in the field of line start permanent magnet synchronous motors

Induced pole rotor structure for line start permanent magnet synchronous motors

Scaled Conjugate Gradient Based Adaptive ANN Control for SVM-DTC Induction Motor Drive

ANN based intelligent control of Induction Motor drive with Space Vector Modulated DTC