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Abstract
This thesis provides rotor position estimation and online inductance estimation using the PWM signals used for motor control. The position estimation technique provides an alternative rotor position information that enables to eliminate the backup position sensor hardware needed for safety critical applications. The sensorless position estimation using PWM based excitation provides the methodology to obtain the position information without influencing the motor performance such as audible noise and torque ripple. The techniques provided can be utilized for online estimation of inductance parameters. These inductance parameters are needed in the reference current calculation in a typical motor control scheme. An Extended Kalman Observer is proposed to enhance inductance and position estimation. Fast sampling of motor phase current is needed to calculate the current slope in the PWM excitation scheme for position and inductance estimation. This thesis provides a methodology of fast current sampling using the microcontroller without sacrificing the processor throughput time. A method to improve the accuracy of the current slope calculation is also provided. This thesis also analyzes the effect of position sensor errors on the performance of the permanent magnet motor drive. The error has significant influence on the motor torque ripple. A mathematical analysis and experimental verification at different operating conditions is provided in this thesis.