Magnetic noise reduction of in-wheel permanent magnet synchronous motors for light-duty electric vehicles

This paper presents study of a multi-slice subdomain model (MS-SDM) for persistent low-frequency sound, in a wheel hub-mounted permanent magnet synchronous motor (WHM-PMSM) with a fractional-slot non-overlapping concentrated winding for a light-duty, fully electric vehicle applications. While this type of winding provides numerous potential benefits, it has also the largest magnetomotive force (MMF) distortion factor, which leads to the electro-vibro-acoustics production, unless additional machine design considerations are carried out. To minimize the magnetic noise level radiated by the PMSM, a skewing technique is targeted with consideration of the natural frequencies under a variable-speed-range analysis. To ensure the impact of the minimization technique used, magnetic force harmonics, along with acoustic sonograms, is computed by MS-SDM and verified by 3D finite element analysis. On the basis of the studied models, we derived and experimentally verified the optimized model with 5 dBA reduction in A-weighted sound power level by due to the choice of skew angle. In addition, we investigated whether or not the skewing slice number can be of importance on the vibro-acoustic objectives in the studied WHM-PMSM.Postprint (published version

High Temperature Superconducting Partial Core Transformers

The thesis begins by providing an introduction to transformer theory. An ideal transformer is examined first, followed by full core transformer theory. The partial core transformer is then introduced and compared to the full core design. An introduction to superconductors is then presented where a simplified theory of superconductivity is given. High temperature superconductors are then examined including their physical structure, superconducting properties and the design of the superconducting wire. The early development of high temperature superconducting partial core transformers at the University of Canterbury is then examined. Early partial core development is discussed followed by some material testing at cryogenic temperatures. This work lead into the development of the first high temperature superconducting partial core transformer. This transformer failed during testing and an examination of the failure mechanisms is presented. The results of the failure investigation prompted an alternative winding insulation design which was implemented in a full core superconducting transformer. The modelling used to design a high temperature superconducting partial core transformer is then presented. Based upon the reverse design method, the modelling is used to determine the components of the Steinmetz equivalent transformer circuit. The modelling includes a combination of circuit theory and finite element analysis. An ac loss model for high temperature superconductors is also presented. A new 15 kVA, 230-230V high temperature superconducting partial core transformer was designed, built and tested. The windings are layer wound with first generation Bi2223 high temperature superconductor. The modelling was used to predict the performance of the transformer as well as the ac losses of the high temperature superconductor. A series of electrical tests were performed on the transformer including open circuit, short circuit, resistive load, overload, ac withstand voltage and fault ride through tests. The test results are compared with the model. The transformer was found to be 98.2% efficient at rated power with 2.86% voltage regulation

Correlation of solar power prediction considering the nominal operating cell temperature under partial shading effect

The steadily rising efficiency together with the accuracy of prediction in solar photovoltaic (PV) energy requires a deterministic reliability in the realistic PV characteristic’s prediction subject to climatic changes. This empirical-based research validates IEC 61853 and improves output power prediction of a solar PV module with considering nominal operating cell temperature (NOCT) using online infrared thermal camera at short range outside. The impact of NOCT consideration is investigated, in which the error can be as high as 10.4¿°C in comparison to non-NOCT. The objective is minimizing the power prediction error for the PV module, the significant parameters of the maximum power point tracking (MPPT) controller are used to evaluate the changes followed by the climatic-related parameters under partial shading condition. A set of non-parametric correlations are calculated using Spearman’s ¿ and Kendall t rank statistical methods to avoid experimental measurement difficulties and cost for an advanced output power prediction. Finally, the differences on the heat distribution of each cell, and its impact in the annual power prediction have been numerically and experimentally verified.Peer ReviewedPostprint (author's final draft

Correlation of solar power prediction considering the nominal operating cell temperature under partial shading effect

The steadily rising efficiency together with the accuracy of prediction in solar photovoltaic (PV) energy requires a deterministic reliability in the realistic PV characteristic’s prediction subject to climatic changes. This empirical-based research validates IEC 61853 and improves output power prediction of a solar PV module with considering nominal operating cell temperature (NOCT) using online infrared thermal camera at short range outside. The impact of NOCT consideration is investigated, in which the error can be as high as 10.4¿°C in comparison to non-NOCT. The objective is minimizing the power prediction error for the PV module, the significant parameters of the maximum power point tracking (MPPT) controller are used to evaluate the changes followed by the climatic-related parameters under partial shading condition. A set of non-parametric correlations are calculated using Spearman’s ¿ and Kendall t rank statistical methods to avoid experimental measurement difficulties and cost for an advanced output power prediction. Finally, the differences on the heat distribution of each cell, and its impact in the annual power prediction have been numerically and experimentally verified.Peer Reviewe