High Performance Reluctance Motor Drives with Three-phase Standard Inverter

摘要

Electric motors perform electromechanical energy conversion within a motor driven system. These electromechanical systems are the most significant type of electrical loads utilizing around 45% of global energy, the vast majority of which is consumed by the electric motor itself. Efficiency improvement of this largest consumer of electricity is critical for saving both energy and environment. In the industrial sector, induction motors (IMs) dominate the motor market. High cost, supply volatility, and detrimental environmental impact of mining rare-earth permanent magnet (PM) materials and simplicity, robustness of IMs have made them the largest shareholder in the field of electrical loads.;Promoting a competitive motor market transformation towards improved efficiency can lead to significant reduction to energy consumption and greenhouse gas emission. In this direction, International Electrotechnical Committee (IEC) has approved a new international efficiency standard to globally harmonize motor energy efficiency. In addition to revisiting the existing IE3 class efficiency, equivalent to premium efficiency class according to National Electrical Manufacturers Association (NEMA), this new IEC standard defines IE4 (superpremium) and IE5 (ultra-premium) class efficiencies. Moreover, compared to line-fed motors, its variable speed drive (VSD) alternative is advantageous in improving overall system level efficiency under variable loads and VSD fed systems are being widely adopted in newly installed motors. This newer technology trends toward improved efficiency motivates the search for low-cost, rare-earth-free, and higher efficiency alternatives to induction motors.;Realizing the need, this dissertation aims at designing reluctance motors (RMs) that have no PMs or secondary windings in its rotor and operate through the principle of magnetic reluctance. As a result, RMs have cooler rotor without any PM or rotor conduction losses. This provides an opportunity in improving the power conversion efficiency with RM drives. This dissertation presents the design, modeling and performance improvement of two RM topologies utilizing three-phase standard voltage source inverters (VSIs) as its drive. Performances of the designed motors have been verified with analytical and semi-numerical models, finite element analysis (FEA), and experimental testing.;A novel design of segmented rotor switched reluctance motor (SSRM) has been developed having compact structure with tooth-wound concentrated windings. The designed SSRM achieves its mutual inductance variation through rotor segments enabling the use of threephase standard VSI. Moreover, with increased contribution from each phase the designed motor has improved torque density compared to conventional SRMs. The major torque ripple sources in SSRM have also been identified and a new rotor segment design is proposed with segmental dip for torque ripple minimization. Finite element analysis (FEA) based multidimensional design optimization including mechanical stress and acoustic noise studies are performed and a prototype SSRM is built and tested. With the application of standard VSIs and conventional motor control, proposed SSRM topology overcomes the major challenge of conventional SRM's commercial adoption.;Design of a synchronous reluctance motor (SynRM) using a new multilayer (ML) distributed winding has been developed. Compared to conventional distributed windings, the ML winding yields a more sinusoidal stator MMF with shorter end-winding length. This translates into the reduction of space harmonics and reduced stator ..2.. losses in the motor. The ML winding is optimized to design an IM (MLIM) and a SynRM (MLSynRM) under a commercial premium efficiency benchmark IM (BMIM) and prototype motors are built. Performance of the test motors are evaluated following the IEEE 112 standard for loss separation and rated efficiency determination. Compared to the premium efficiency BMIM, the designed MLIM and MLSynRM can attain super-premium and ultra-premium efficiencies, respectively under the same frame size and cooling type. This new multilayer winding configuration can be a technology trend in gaining efficiency improvement with low cost non- PM designs under the standard frame sizes.