Design and Analysis of High Gain Bidirectional Converters for PMBLDC Motor in Electric Vehicle Application

Abstract

The depletion of fossil fuel resources, the adverse environmental impact of greenhouse gases, and the advent of power electronics have increased the interest in Electric vehicles (EVs). The culminated effect of the price hikes in fuel and easy availability of cheap electric power has motivated the public acceptance of this emerging era of EVs. In EVs, the internal combustion engine is replaced by an electric motor. Switched reluctance motor, induction motor, and Permanent magnet brushless DC (PMBLDC) motor are the most popular drivers in the powertrain of EVs. Among these, PMBLDC motors are being used extensively due to their high starting torque, less maintenance, high torque density, and high efficiency. newlinePMBLDC motors have added advantages of easy control and regenerative braking capability. The EVs have a low battery voltage of 24-48 Volts. Thus, operating motors at these low voltage levels increase the operating current leading to increased heating and losses in the system. A DC-DC converter can be employed to boost the battery voltage in order to get a high voltage DC link to drive the PMBLDC motor. To perform regenerative braking on the motor a bi-directional buck-boost converter is required to fulfill the demand of bidirectional power flow. Conventional buck-boost converter can not provide high voltage gain at a low duty cycle, which leads to newline newline an increased conduction loss and newline reverse recovery problem in the diode. newline newlineThus, quadratic gain bidirectional buck-boost converters can be used to alleviate the above-mentioned problems. A vast literature survey on recently proposed topologies of bidirectional buck-boost converters is included in the thesis. Finally, three novel quadratic bidirectional buck-boost converter topologies are presented for electric vehicle application. newline newline