Modeling And Analysis Of Multi–Phase Permanent Magnet Synchronous Machines: Direct–Drive Electric Vehicle Application

In commercially existing electric vehicles (EVs), power is transferred from the motor to the wheels through a fixed gear mechanical transmission system. However, such a transmission system contributes to a power loss between 2% to 20% of output power of the motor depending on the operating speed and torque of the motor. Therefore, by removing the transmission, a direct–drive EV configuration is obtained with lower component count, improved motor to wheel efficiency and frequency dependent losses. However, challenges in developing a single on–board permanent magnet synchronous machine (PMSM) for such a configuration include high torque density, low torque ripple and high torque per permanent magnet (PM) volume. Therefore, this dissertation proposes a novel PMSM addressing the aforementioned challenges for a direct–drive application. Initially, the design targets, stator and rotor configuration and phase numbers of the PMSM are chosen to satisfy the requirements of a direct drive application. A novel torque and torque ripple model based on multiple reference frames is proposed, in which the torque ripple from spatial harmonics of flux, inductances and the time harmonics of stator currents are included. Using the analytical model, optimal slot–pole combination of the machine is selected based on adaptive gradient descent algorithm. A new consequent pole rotor topology is proposed to improve the torque density and torque per PM volume thereby reducing the usage of expensive rare earth magnets. The proposed PMSM with novel rotor is further improved in terms of torque density, losses and cost by performing an intensive structural optimization based on novel hybrid analytical model, finite element analysis and supervised learning. The optimized PMSM is then analyzed for various drive cycles and performance in terms of torque, speed and efficiency are discussed. A scaled–down prototype of the proposed PMSM is developed and comprehensive experimental analysis in terms of torque ripple, torque–speed characteristics and efficiency are performed under different speeds and load conditions and are compared with the results obtained from proposed analytical model

On the Modeling, Analysis and Development of PMSM: For Traction and Charging Application

Permanent magnet synchronous machines (PMSMs) are widely implemented commercially available traction motors owing to their high torque production capability and wide operating speed range. However, to achieve significant electric vehicle (EV) global market infiltration in the coming years, the technological gaps in the technical targets of the traction motor must be addressed towards further improvement of driving range per charge of the vehicle and reduced motor weight and cost. Thus, this thesis focuses on the design and development of a novel high speed traction PMSM with improved torque density, maximized efficiency, reduced torque ripple and increased driving range suitable for both traction and integrated charging applications. First, the required performance targets are determined using a drive cycle based vehicle dynamic model, existing literature and roadmaps for future EVs. An unconventional fractional–slot distributed winding configuration with a coil pitch of 2 is selected for analysis due to their short end–winding length, reduced winding losses and improved torque density. For the chosen baseline topology, a non–dominated sorting genetic algorithm based selection of optimal odd slot numbers is performed for higher torque production and reduced torque ripple. Further, for the selected odd slot–pole combination, a novel star–delta winding configuration is modeled and analyzed using winding function theory for higher torque density, reduced spatial harmonics, reduced torque ripple and machine losses. Thereafter, to analyze the motor performance with control and making critical decisions on inter–dependent design parameter variations for machine optimization, a parametric design approach using a novel coupled magnetic equivalent circuit model and thermal model incorporating current harmonics for fractional–slot wound PMSMs was developed and verified. The developed magnetic circuit model incorporates all machine non–linearities including effects of temperature and induced inverter harmonics as well as the space harmonics in the winding inductances of a fractional–slot winding configuration. Using the proposed model with a pareto ant colony optimization algorithm, an optimal rotor design is obtained to reduce the magnet utilization and obtain maximized torque density and extended operating range. Further, the developed machine structure is also analyzed and verified for integrated charging operation where the machine’s winding inductances are used as line inductors for charging the battery thereby eliminating the requirement of an on–board charger in the powertrain and hence resulting in reduced weight, cost and extended driving range. Finally, a scaled–down prototype of the proposed PMSM is developed and validated with experimental results in terms of machine inductances, torque ripple, torque–power–speed curves and efficiency maps over the operating speed range. Subsequently, understanding the capabilities and challenges of the developed scaled–down prototype, a full–scale design with commercial traction level ratings, will be developed and analyzed using finite element analysis. Further recommendations for design improvement, future work and analysis will also be summarized towards the end of the dissertation

Adaptive control of the interior permanent magnet synchronous motors

Thesis contains: pages – 117, drawings – 38, tables – 23. The goal of the of the thesis lies in development of the control methods of the IPMSM with the purpose of its research and improvement of efficiency and performance of the electromechanical system. In this thesis, analytical review of the inductance determination methods for the IPMSM is presented. After that two tests for inductance determination of the interior permanent magnet synchronous motors are proposed, analyzed and experimentally verified. Four methods are proposed to use to obtain static and dynamic inductances from the tests data. Speed and position control algorithms are derived basing on the non saturated model of the motor and its effectiveness was researched by means of experiment and simulation for small saturated motors. After that position control algorithm with adaptation to the mechanical parameters is designed and tested via simulation. Stability is proved using the second Lyapunov method. Derived algorithms provide asymptotic tracking of the controlled coordinates, and decoupling of the direct current component and mechanic coordinate control subsystems.Магістерська дисертація містить: 117 сторінок, 38 рисунків, 23 таблиці. Метою роботи є розробка та розвиток методів керування явнополюсними синхронними двигунами з постійними магнітами, спрямований на покращення ефективності електромеханічної системи. В роботі представлено аналітичний огляд методів визначення індуктивностей IPMSM. Запропоно та експериментально впроваджено два тести для визначення індуктивностей. Отримані в тестах данi пропонується обробити чотирьма методами для отримання значень статичної та динамічної індуктивностей. Розроблено алгоритми керування швидкістю та подоженням на основі моделі, що не враховує насичення. Ефективність алгоритмів досліджена шляхом моделювання та експериментально для двигуна з низьким рівнем насичення. Після цього синтезовано алгоритм керування положенням з адаптацією до механічних параметрів. Стабільність системи доведена за допомогою другого методу Ляпунова. Отримані алгоритми забезпечують асимптотичне відпрацювання контрольованих координат та розв’язку підсистеми керування прямою компонентою струму та підсистемою керування механічними координатами