Design, analysis and operation of IPMSMs for HEV applications

Energy conservation and clean environment are the basic driving factors for the development of Hybrid and Electrical Vehicles (HEVs). Efficient electrical machines are one of the key components of HEVs. Interior Permanent Magnet Synchronous Machines (IPMSMs) are getting more room in the vehicle industry due to their high power density, wide speed range and high efficiency. This document presents the different aspects of the design, analysis and operation IPMSMs for HEVs applications. Finite Element Method (FEN) and analytical methods are used for performance analysis. The issues addressed are efficient machine design for a specific driving cycle, quantitative analysis of machine's performance under overload conditions, effect of magnet materials on machine design and an analytical framework for faster calculation of machine losses and torque.;An efficient design of IPMSM is proposed for series hybrid bus based upon the maximization of the Average Driving Cycle Efficiency (ADCE) for a typical urban driving cycle. An optimized machine design is the outcome of many design iterations and procedure involves FEM analysis for every design. Design iterations were tuned for machine geometry and winding topology. Torque speed envelopes and efficiency maps were computed by post processing of the FEM simulations data and Matlab programming. Inverter losses and the power required for machine and inverter cooling was also included in the computation of ADCE.;A method based upon the quantitative analysis is suggested to design and evaluate the performance of an IPMSM under overload conditions with increased cooling. Issues of demagnetization of the magnets and the current magnitude and angle limits were calculated using the FEM. The procedure was demonstrated to design and analyze an IPMSM to maximize the overloading capacity.;An analysis is presented for performance evaluation of high power density IPMSMs for elevated operating temperature using different magnet materials. The effect of change in the characteristics of the permanent magnets with temperature variation is taken into account in the design evaluation. NdFeB and SmCo magnet machines can be designed for a specific temperature range. The availability of rare earth magnet materials (NdFeB and SmCo) across the world at affordable cost, is becoming an issue. In this situation, the ferrite magnets could be the only option for design of high power density PM machines. Different machine designs including IPM and flux squeeze were analyzed and their performance is compared to explore an efficient machine design using ferrite magnets.;FEM takes hours to set up, run and data post-processing of the experiments for every iteration. An iterative method based upon large elements and 'Magnetic Equivalent Circuit (MEC) of the machine is developed to reject out the relatively non-efficient designs at early stage of the design optimization. It encompasses the time stepping transient solution of the magnetic scalar potential of a set of equations derived from the MEC of mum IPMSM Finally, losses and efficiency of the machine were calculated from magnetic scalar potential of MEC nodes in much reduced time than required by the FEM.;Six PMSMs are designed and manufactured during this research work. First IPMSM is in use for various experiments in the machines test laboratory for more than two years. Three more machines are built using different magnet materials (one each of NdFeB, SmCo and ferrite magnets) in the housing of off the shelf induction machines. Two high power, water cooled IPMSMs were designed for the power train of series hybrid bus and their manufacturing was arranged through a vendor.