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In this thesis, it is aimed to reduce the torque ripples occurring during commutation of phase currents of brushless direct current motors (BLDCM) operating at both low and high speeds by using direct current (DC) link voltage control technique. This technique is achieved by placing a DC-DC converter in front of the inverter to obtain the voltage level required to equalize the slopes of the incoming and outgoing phase currents during commutation at the maximum level. A mode selector circuit is designed for this operation. The mode selective circuit was used in the commutation times. Except for commutation time was used the normal source voltage of the BLDCM. The simulation studies carried out under different load and different speed conditions. When the simulation results are compared with those of the traditional BLDCM, it was observed that the torque ripples occurring in commutation decreased considerably.
In this thesis, a novel Energy Management System (EMS) has been proposed for Electric Vehicles (EVs) with Battery and Supercapacitor Hybrid Energy Storage System (HESS). This method is fundamentally based on separating the load current into low and high frequency components with the help of a Low Pass Filter (LPF) and allocating it to the sources. To filter the load current, the adaptive AGF is designed according to the amplitude of the load current and the supercapacitor state of charge. In addition, the battery current has been made adaptive by limiting it to a specific operating percentage according to the supercapacitor state of charge. Double adaptive power allocation is achieved by adapting the filter cut-off frequency and the battery current. The proposed method has been designed and examined both by simulation and experimentally. When the results obtained are compared with the load current filtering methods presented in the literature, it has been observed that the method proposed in this thesis has higher energy efficiency because it requires lower battery current and can use the energy stored in the supercapacitor more effectively.