DOI: https://doi.org/10.15368/theses.2021.2
Available at: https://digitalcommons.calpoly.edu/theses/2252
Date of Award
3-2021
Degree Name
MS in Electrical Engineering
Department/Program
Electrical Engineering
College
College of Engineering
Advisor
Taufik
Advisor Department
Electrical Engineering
Advisor College
College of Engineering
Abstract
This thesis entails the stability analysis of the Multiple Input Single Output (MISO) DC-DC converter developed for the DC House Project at Cal Poly. A frequency domain control system model of the MISO converter was designed and constructed using MATLAB Simulink. Transfer functions were derived and modeled for each stage of the converter to best fit the converter circuit system used in the original MISO circuit. Stability metrics such as overshoot, undershoot, rise time, phase margin and gain margin were measured to evaluate and analyze the stability of the converter. These metrics were measured with the original model including the current sharing network that allows load sharing between multiple MISO modules. The simulation results demonstrate that based on the existing model, the system is stable with a gain margin of infinity and phase margin of around 40 degrees at crossover frequency of 47kHz with nominal input voltage of 24V. Another compensator was proposed to overcome the shortcomings of the original compensator model with respect to the overshoot and phase margin. The new compensator model improved the phase margin at the same crossover frequency with a higher rise time and lowered percent overshoot. Additional improvements and tradeoffs are further discussed to help with the decision when designing a compensator for DC-DC converter that uses the current mode control technique.