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Thermal Management of Electric Motors / Permanent Magnet Synchronous Motors (PMSMs) have garnered widespread adoption in electric vehicles owing to their exceptional characteristics, including high power density, robust torque capability, and superior efficiency compared to conventional electric motors. Implementing permanent magnets facilitates the absence of a heat source on the rotor side, contributing significantly to their exceptional performance. However, despite these advantages, the heightened vulnerability of permanent magnets necessitates rigorous thermal management and analysis for PMSMs, particularly during short-duration peak performances and steady-state continuous operations. Operating under such conditions can potentially adversely affect the permanent magnets, winding insulation, and overall motor performance. Therefore, addressing thermal concerns associated with PMSMs emerges as a critical endeavor. This research tackles these thermal challenges by employing a combined approach of Lumped Parameter Thermal Network (LPTN) and Computational Fluid Dynamics (CFD) for accurate and cost-effective thermal modeling. A CFD analysis is performed to analyze the effect of water jacket and oil splash cooling and to calculate the heat transfer coefficients resulting from these two methodologies. A conjugate heat transfer CFD model is used to analyze the water jacket with the aid of a multi-phase CFD model to simulate the effect of the oil splash on end-windings. CFD heat transfer coefficients are then integrated into an LPTN model to calculate the temperature distribution of the motor. Furthermore, a comparative analysis is used to show the difference between integrating CFD-derived heat transfer coefficients and the analytical heat transfer coefficients in the LPTN model. VI In summary, this research underscores the importance of effective thermal management in maximizing the performance and longevity of PMSMs in electric vehicles. By leveraging advanced modeling methodologies, it seeks to address the intricate thermal concerns associated with PMSMs, paving the way for significant advancements in electric vehicle technology and inspiring sustainable transportation solutions. / Thesis / Master of Applied Science (MASc) / Electric vehicles are crucial for the future of sustainable transportation, offering a cleaner alternative to conventional combustion-engine cars and helping reduce greenhouse gas emissions. Permanent Magnet Synchronous Motors (PMSMs) are key to their performance, providing high efficiency and power density. However, their effectiveness can be hindered by thermal issues, particularly during peak performance or continuous operation. This research addresses these thermal challenges by combining Lumped Parameter Thermal Network (LPTN) models with Computational Fluid Dynamics (CFD) simulations. By analyzing water jacket and oil splash cooling systems, the study calculates heat transfer coefficients and integrates these into the LPTN model to assess motor temperature distribution. The research highlights the critical role of effective thermal management in enhancing PMSM performance and longevity, aiming to advance electric vehicle technology and support sustainable transportation solutions.

The frequency of a Pulse Width Modulated (PWM) power source can be adjusted to control the speed of an AC machine. Machine response in this mode of operation depends strongly on the quality of the chosen PWM switching strategy. Several methods of PWM waveform synthesis are presented and new methods are introduced. A novel Relaxed Spectrum (RS) algorithm based on a Fourier series expansion of the PWM signal is presented. The algorithm computes sinusoidal and non-sinusoidal switching patterns from a specified set of harmonic coefficients. The RS method is suitable for both full- and half-bridge PWM invertors. Unwanted harmonics inherent in a PWM signal, are exploited to induce excitation into the rotor of a synchronous machine. Rotor mounted diodes are used to rectify the induced currents. 'Rvo novel induced excitation methods are presented which permit accurate control of excitation levels. Whilst the first method uses a single Excitation Harmonic Voltage (EHV) for rotor excitation, an EHV pair is used in the second method to obtain improved machine response. The RS algorithm is applied to obtain a PWM waveform which approximates closest to a given specification. PWM switching patterns are obtained for most possible excitation conditions. Voltage Control Limit Functions (VCLF) are computed which define control limits for several excitation schemes. The response of a computer simulated machine model to an Ideal Test Voltage (lTV) is investigated to assess the performance of the new methods of machine excitation. Simulation reveals that the use of an EHV pair minimises motor torque pulsation. Optimum excitation ratios are then defined in terms of the harmonic indices of a given EHV pair. These ratios are shown to be largely independent of machine parameters. The RS method is used t(] compute generalised sets of PWM switching sequences which can subsequently be applied to a wide range of differently rated machines. Analogue Symmetrical Sample (SS) PWM waveform synthesis methods for induce( excitation are compared with their digital equivalents. It is shown that digital P~ techniques compare favourably and can provide higher excitation levels when a largl fundamental drive voltage is required.

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No description available.

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No description available.