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FPGA implementation of field oriented control forpermanent magnet synchronous motor

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2019
Irmak, Gizem
The thesis study focuses on the fully operational FPGA implementation for the current/torque control of a Permanent Magnet Synchronous Motor. 3-phase synchronous motors with permanent magnets can be categorized into two categories as Permanent Magnet Synchronous Motor (PMSM) and Brushless Direct Current (BLDC) motor. The main difference between PMSM and BLDC is the shape of the induced back-EMF voltage. While BLDC motors have trapezoidal shaped back-EMF, PMSMs have a sinusoidal back-EMF. In order to take advantage of PMSM, the waveform of motor phase currents should also be created as sinusoidal waveform. For this purpose, Sinusoidal Commutation (SC) and Field Oriented Control (FOC) are the most common strategies in the literature. FOC with Space Vector PWM (SVPWM) is superior to SC in terms of wider speed operation range and higher torque efficiency and hence is the focus of this thesis. Within the scope of our study, Proportional Integral (PI) and Linear Quadratic Regulator (LQR) current and speed controller alternatives are designed. These alternatives are compared in a simulation environment for the considered PMSM. In order to analyze the performance, a detailed system model of the considered PMSM is also created. Matlab/Simulink is used for the construction and test of the simulation models. For the hardware validation and performance evaluation of the design, the PI current/torque controller is implemented in FPGA using VHDL language. Hardware experimental work is conducted on a custom design electronic board. Torque tracking ability of the current controller is analysed by using a number of test setups. Additionally, comparative performance analysis of the two competing commutation methods, namely the FOC and trapezoidal implementations, has been done. Apart from a fully functional FPGA realization, our study demonstrates the superiority of FOC over trapezoidal commutation in terms of reduction in both torque ripple and required sampling rate.