ANALYSIS AND CONTROL OF DC DC CONVERTER

Abstract

The work presented in this dissertation is the study of non-isolated dc-dc converters and their control to provide a regulated output dc voltage with least ripples and fluctuations with the change in circuit parameters. Steady state modeling of dc-dc converters in continuous conduction mode using state space averaging is discussed. This provides with a clear insight into the behavior of dc-dc converters. The circuits that are considered in this dissertation are buck converter, elementary Luo converter, self-lift Luo converter, super-lift Luo converter and ultra-lift Luo converter. Further, to control the outputs of these converters, PI control technique is implemented to improve the system performance and create fewer fluctuations during parameter changes to the circuit. A sliding mode controller is proposed and implemented on these converters that reduces the ripples in output voltage and can achieve better dynamic response than PI controllers. MATLAB-Simulink models of these converters are designed and PI control and the proposed sliding mode control are implemented. Presented assay of proposed SMC can enact steady frequency of switching with reduced ripples in output . Error in steady state of the converters is reduced and the output tracks a desired reference voltage despite disturbances caused in the supple voltage and resistance at load. The devised sliding mode controller in this dissertation aims at achieving minimum steady state error & chattering in the converters. The results from an uncontrolled and PI controlled converter is compared with that of SMC and conclusions are drawn.