Development of digital controller for permanent magnet dc motors with applications

This work concerns with designing and implementing of a system which is competent enough to resist the disturbances on the DC motors, fed by a step-down DC-DC power converter. The electrical component values of the buck converter and its appendix (bootstrap circuit) have been opted minutely in strict range to guarantee the minimal dissipation losses during power conversion. Furthermore, this work involves using an optical speed sensor for feeding back the actual speed into Proportional Integral controller which is implemented on PIC18F4580. For the PI tuning, the fourth order transfer function that describes the whole system precisely has also been derived and converted from the continuous to the discrete domain. At the end, the data was sent via UART pin to an Arduino UNO which works here as a data acquisition with the help of PLX-DAQ software, forming a Microsoft Excel file. The simulation results have been presented in the time domain for checking the DC motor parameters estimation and the relationship between both of the duty cycle and the speed versus the time. In addition, the results have been presented in the frequency domain for testing the stability of the system via bode plot. To show the efficiency of the designed system, both the duty cycle and the output voltage of the buck converter have been presented and analyzed. Moreover; the actual, the desired speed of the DC motor and the error between them for two different speed cased are also presented and discussed.