Design and Implementation of a Brushless DC Motor Drive for an Electric Vehicle

Abstract

Since the cost of fossil fuels is gradually increasing day by day as well as government policy is also towards the minimization of atmospheric pollution, it is mandatory for the human being to concentrate more on designing a hybrid vehicle powered by re-chargeable batteries with an efficient technique. Advances in battery technology and significant improvements in electrical motor efficiency have made electric vehicles an attractive alternative, especially for short distance commuting. The aim for this project is to design and implement an efficient controlling of electric powered vehicle using Permanent Magnet Brushless Direct Current (PMBLDC) motor, which is most effective option and with good dynamic control like shunt DC motor. The work presented in this report deals with understanding that why need a dc-dc converter to control the motor although the inverter can control the motor speed itself, the working of the PMBLDC motor and reason to choose this particular motor. The simulation of a tentative designed buck converter to control a PMBLDC motor drive is carried out. The buck converter is used to vary the speed of the motor, which is controlled by changing the duty cycle of the buck converter from 0-95%, which will vary the DC link voltage supplied to the motor. There is a disadvantage of the electrical vehicles, that it draws very high current at the starting, and it draws that much current every time its being started. To get the efficiency, hybridization of the system might help. Today, super-capacitor is being used for the starting purpose, but there is an issue on the cost-effectiveness also. Recent advancement in the hybridization shows the scope in the hydraulic-electric hybrid system. This system uses the hydraulic power which has the best in segment power to weight ratio as well as high power density. It is used in the acceleration of the vehicle, and when the vehicle speed reaches at its desired speed, the load will be shifted on the electric system which is efficient in the cruising mode of operation. For regenerative purpose, the hydraulic power gives the better performance than the electric system as it used mechanical to mechanical power flow. Thesis shows the detailed operation of the electric-hydraulic hybrid system and both, the electric as well as the hydraulic system performance simulated separately.