Research on Sensorless control strategies for Vehicle stability using Fuzzy based EDC

This paper presents an efficient and robust control scheme of Fuzzy Logic Electronic Differential Controller (FLEDC) for sensorless drive based electric vehicle. The proposed system consists of two Brushless DC motors (BLDC) that ensure the drive of the two back driving wheels of an electric vehicle. Electronic differential controller (EDC) ensures the maximum torque and it can control both the driving wheel independently to turn at different speeds in any curve according to the steering angle. The sensorless control strategies include back EMF zero crossing detection and third harmonic voltage integration. Fuzzy logic based EDC is used on these sensorless control strategies which optimizes the slip rate within the specified limit and thus enhances the vehicle stability The performances in terms of slip rate, current, Torque, back EMF are obtained by the proposed method and are compared with those obtained using conventional control method. By this comparative investigation, a suitable control strategy has been identified. The effectiveness and substantiation of these analysis are ascertained in the MATLAB/Simulink environment and also experimentally validated. I. INTRODUCTION Environmental and economical issues are the major driving forces in the development of electric vehicles (EVs).The selection of the right electric motor is the primary importance to the EVs. Several types of electric motors have been used in the past for EV applications. However from efficiency point of view, BLDC motor drives are the best choice for EV is explained in [1]. In particular, the BLDC motor of the hub type is used in this work to avoid mechanical transmission losses. BLDC motors with their electromagnetic force (EMF) requires six discrete rotor position information for the inverter operation. These are generated by Hall-effect sensors placed within the motor. However it is a well known fact that these sensors have a number of drawbacks. So, sensorless control is the only viable option to operate the motor for applications in harsh environments. Thus many of the drawbacks can be eliminated or reduced with position sensorless operation based on the back EMF of the motor. Many research works on sensorless control technique for BLDC have been conducted and reported in [6]. A deep overview of back EMF sensing methods of BLDC motor which includes terminal voltage sensing, third harmonic voltage integrations and Terminal current sensing techniques are briefly analyzed in [7]. Further, Electronic Differential Controller (EDC) is used in this research work to avoid mechanical differential system. EDC based …