MODELLING, ANALYSIS AND CONTROL OF TRISTATE DC-DC CONVERTERS FOR LOW POWER CIRCUITS

Abstract

In the realm of DC-DC converters, boost and buck-boost converters serve a significant role. These converters are extensively utilized in various applications due to their proficiency in modulating and transforming voltage levels. Boost converters are commonly employed in photovoltaic systems, electric vehicles, and portable electronic devices to elevate low input voltages to higher levels, ensuring an adequate power supply. Buck-boost converters are essential in battery-powered systems, including laptops and mobile devices, providing both step-up and step-down voltage regulation. Both varieties are crucial for augmenting the efficacy and reliability of power management systems. A significant issue with both boost and buck-boost converters are the presence of the right-hand plane zero, which impacts their stability. The advent of the Tristate converter in boost and buck-boost configurations has mitigated this problem by eradicating the right-hand plane zero, thereby enhancing the stability of both converters. Consequently, the Tristate converter is used to modulate the voltage of the DC grid. This project investigates the performance of the Tristate boost converter with two different types of controllers: PI controllers and Type II compensators. An analogous analysis is conducted using a boost converter. Additionally, the development of the Dual Output Tristate Boost Converter is investigated. This converter features an incorporated output: the main output exhibits the characteristics of a Tristate boost converter, while the auxiliary port produces a buck characteristic. The secondary port is controlled through a buck-boost converter affixed to the auxiliary port's output. A comparative analysis between the buck-boost converter and the Tristate buck-boost converter is presented, concentrating on steady-state output voltage gain and stability conditions illustrated through bode plots and root locus. This comparison emphasizes the superiority of the Tristate buck boost converter over the standard buck-boost converter. The only disadvantage of the Tristate converter is its steady-state output gain, which is addressed by the high-gain Tristate converter. The chapter on the high-gain Tristate converter details its derivation in buck-boost and boost configurations and portrays its steady-state performance. The report concludes with a segment on future scope, delineating potential advancements for the Tristate converter.