PWM Current Controlled Permanent Magnet Brushless Dc Motor Drive for Electric Vehicle Application

Abstract

Electric Propulsion drives are gaining popularity as a technology for battery operated vehicles. This technology has the inherent advantage of energy conservation and being environmental friendly. The objective of the present work is to design and develop a controller for Permanent Magnet Brushless DC (PMBLDC) Motor to be used in electric vehicle. Based on the literature survey on the existing converter topologies and the control algorithm, VSI based PWM controlled PMBLDC Motor is proposed for the present study, the control algorithm has been implemented using hard switching. Since this algorithm can be effectively used in battery-operated drive and also provides the advantage of compactness. PMBLDC Motor having a trapezoidal back e.m.f requires rectangular stator currents to produce constant torque. Because of non-sinusoidal variation of the mutual inductances between the stator and the rotor in PMBLDC motor, abc phase variable model is used for the modeling. The control algorithm has been simulated and implemented. Implementation of the controller includes the design and fabrication of three-phase MOSFET based battery operated voltage source inverter and the control algorithm. The control circuit has been fabricated using operational amplifier and logic gates. The control algorithm has been first verified for a 10 Ω, 500 W, star connected three-phase resistive load. Then after the control logic has been verified with PMBLDC motor. The phase displacement of the Hall position sensors has been determined. The accelerator output has been used to generate a PWM signal (1 kHz). The rotor position feedback and the PWM signal have been used to derive the switching commands for the six-inverter switches. By changing the modulation index at a given switching frequency of 1 kHz, the speed of the motor can be varied. The proposed control algorithm is implemented on the resistive load and then it is applied to the PMBLDC motor under study. However the control strategy used in this work, results in high acoustic noise in the motor operation and this issue can be considered as a scope of further work.