Comparison of three- and nine-phase hybrid permanent magnet generators

Escalating worldwide concerns over energy consumption and pollution due to transportation systems have increased the importance of optimizing hybrid electric vehicles (HEV). In series HEVs, which contain hybrid permanent magnet (HPM) instead of conventional brushless permanent magnet generator, the optimum operating region of the internal combustion engine (ICE) in terms of fuel consumption and emission can be realized by levelling of the vehicle energy demand via controlling HPM excitation field that will permit the downsizing of ICE power capability. Efficient and optimum energy transmission from HPM to the dc-link in series HEVs is desired. Therefore, advantages and disadvantages of using multiphase machines with a passive rectifier stage as opposed to an active converter is investigated, since they may or may not permit the achievement of some technical operating merits that present an advantage over their three-phase counterparts. This paper presents a comparative study of three- and nine-phase HPM generator configurations with their passive converter stage at rated conditions. Dynamic models of the proposed machines with their three- and nine-phase power electronic rectification stage are developed and the dynamic behaviour of the system, have been numerically evaluated via Matlab/Simulink. Feasibility of using a smoothing capacitor to improve the quality of dc output voltage ripple in the three-phase configuration case is discussed.