Autonomous converter control for hybrid energy storage system (HESS) in active buildings

Abstract

Hybrid Energy Storage Systems (HESS) have evolved as a promising solution for managing dynamic power demands in active buildings by combining high-power density and high-energy density storage devices. Nevertheless, the design of efficient, high-gain, and compact bidirectional DC-DC converters remains a critical challenge. Conventional buck-boost converters struggle with achieving high voltage gain and efficient bidirectional power flow. To address these limitations, this thesis presents a new non-isolated bidirectional DC-DC converter design that delivers a high voltage gain of 25 at a low duty cycle, using a minimal number of switching components. The proposed converter supports an input voltage range of 25V to 45V, delivers a rated output voltage of 625V, making it suitable for high-voltage energy storage integration. A Proportional-Integral-Derivative (PID) based voltage control scheme is developed for output regulation. The proposed design utilizes voltage sensor to create a costeffective and straightforward control system. This feedback is then used to compare against a reference voltage the error signal is fed into the PID controller which processes it and generates a control signal which is then fed into a pulse width modulation generator, which produces switching signals to achieve desired output. Another voltage mode control is developed using a Type-II compensator to enhance dynamic performance and stability. Furthermore, the paper elucidates the mathematical modeling and operational modes of the converter. Simulation results validate the converter’s high voltage gain and improved transient response under dynamic load conditions.