Marian K. Kazimierczuk, Ph.D. (Advisor); Raúl Ordóñez, Ph.D. (Committee Member); Saiyu Ren, Ph.D. (Committee Member); Yan Zhuang, Ph.D. (Committee Member); Xiaodong Zhang, Ph.D. (Committee Member)
Doctor of Philosophy (PhD)
The pulse-width modulated (PWM) dc-dc converters play a vital role in several industrial applications that include motor drives, electric vehicles, dc distribution systems, and consumer electronics. The switched-mode power converters step the input voltage up or down based on their typology and provide a regulated output voltage. The stability and regulation performance of a power converter can tremendously be improved via a suitable control design. However, due to the nonlinearity of the power converters and the presence of the line and load disturbances, the design of a robust and low-cost control circuit becomes a challenging task. The sliding-mode control of the dc-dc converters has been studied for decades because of its robustness, design simplicity, and suitability for variable structure systems. Despite the merits of the sliding-mode control method, the linear controllers are still dominant and attractive to the commercial applications since they require less design efforts and can be implemented using simple analogue circuits. This research aims to develop simplified sliding-mode control circuits for the classical PWM dc-dc converters in continuous-conduction mode (CCM). The control objectives are to maintain a constant switching frequency, enhance the transient response, provide wide operating range, and track the desired reference voltage under large disturbances. In order to design and test the control circuit, an accurate power converter model should be derived. Hence, large-signal non-ideal averaged models of dc-dc buck and boost converters in CCM are developed. The models are simulated in MATLAB/SIMULINK and compared with the corresponding circuits in SaberRD simulator for validation purpose. Next, PWM-based simplified sliding-mode voltage and current control schemes are designed for the dc-dc buck and boost converters in CCM, respectively. The design procedure and the analogue realization of the control equations are presented, where the control circuits are constructed with minimal added components. The derivation of the existence and stability conditions is also provided to select the controller gains accordingly. The closed-loop control systems are simulated in MATLAB/SIMULINK and SaberRD under various operating conditions to validate the design approach. The tracking, disturbance rejection, and regulation performance have been investigated. Finally, a PCB prototype of a simplified sliding-mode voltage controlled PWM dc-dc buck converter is designed and tested under large disturbances condition, where the experimental results have showed a good agreement with the simulated results.
Department or Program
Ph.D. in Engineering
Year Degree Awarded
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