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

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

Line-start synchronous motors (LSSMs) have been recently introduced in the motor market to meet the new efficiency class requirements. They exhibit high efficiency and power factor compared with induction motors (IMs), but the complex design, manufacture, and high cost due to presence of permanent magnets (PM) limit their widespread use. This paper proposes a new approach for the design of LSSMs, in which an important torque contribution is given by the reluctance torque component. Both steady-state and dynamic capabilities are considered. A stochastic optimization is used to determine the parameters that maximize the synchronous torque. The possibility to apply the recent improvements on the synchronous reluctance machine design to LSSMs is discussed. Experimental measurements are carried out on an LSSM prototype achieved from the optimization. The results are compared with the predictions. Two different PM volumes are tested in the same rotor structure, evaluating their impact on motor performance. From the experimental tests, an overview comparison between the IM and LSSM performance is given.

Line-Start PM-Assisted Synchronous Motor Design, Optimization, and Tests

The design and analysis study for the conceptual design of an economical high-efficiency ac motor based on permanent magnets is summarized. Material considerations, design trade-off options as well as transient and steady-state performance under normal and abnormal conditions have been considered. The baseline comparison is the high-efficiency induction motor. The permanent magnet (PM) motor must fit into the same frame size and surpass the induction motor on a life cost basis that includes 2.5 years of operation at a 50 percent duty cycle. The study results indicate that a motor with ferrite magnets meets the objectives of the program in ratings of up to 25 hp. A 7.5-hp motor design is carried through the conceptual design stage.

The ferrite permanent magnet AC motor: A technical and economical assessment

This paper presents an in-depth comparative analysis of the variable speed drive (VSD) performance between an IEC frame size 90 four-pole three-phase induction motor (IM) and the equal line-start interior permanent magnet synchronous motor (LSIPMSM). Employing measurement data from no-load tests, load tests, and temperature-rise tests of the aforementioned motors and different cage materials as well, the motors' no-load and load characteristics are first examined in detail and then the drives' characteristics are analyzed in open-loop volts per hertz (V/f) control by using the same voltage-source inverter and the aforementioned IM or LSIPMSM in both constant torque and constant power operation. It has been established that particularly the motors' current and power factor characteristics have distinct impact on the consequent VSD performance in terms of loss and efficiency. Furthermore, it has been shown that the lower loss of the LSIPMSM enables a significant increase of the VSD's constant power range.

Comparison of Induction Motor and Line-Start IPM Synchronous Motor Performance in a Variable-Speed Drive

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

Direct torque and flux control of ac machines is well established technique getting increasingly adapted in industry This technique like other high performance control methods such as vector control is rarely applied to single phase machines However, development of high performance low power drives is receiving some attention This paper investigates the performance of single phase direct torque controlled induction motor drive Unified modeling approach is used to adapt direct torque control (DTC) of both symmetrical as well as asymmetrical single phase induction motor It is also demonstrated that it is possible to take winding and angle asymmetry into accounts The drive is simulated using Simulink platform and the results are presented

Direct Torque Control of Symmetrical and Asymmetrical Single Phase Induction Motor

This work presents a new interior rotor type permanent magnet synchronous motor with direct on line starting ability, which employs both circumferentially magnetized as well as radially magnetized magnets, and consequent pole concept resulting into better steady state performance. Two dimentional (2D) time-stepping finite element analysis (FEA) has been employed in prediction of transient and steady state performance. The experimental prototypes of line start permanent magnet synchronous motor (LSPMSM) using proposed magnet arrangement in the rotor, have been developed, tested and validated in the laboratory. Simulation and experimental results indicate that the proposed magnet arrangement gives improved performance, than other magnet arrangements previously used for this machine, for a given magnet volume.

R. T. Ugale

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

Direct Torque Control of Symmetrical and Asymmetrical Single Phase Induction Motor

A new rotor structure for line start permanent magnet synchronous motor