Abstract

Batteries, ultra capacitors (UCs), and fuel cells (FCs) are widely being proposed for electric and plug-in hybrid electric vehicles (EVs/PHEVs) as energy sources. The increasing popularity of EVs and PHEVs can be attributed to the savings in fuel costs, compared to conventional internal combustion engine (ICE) vehicles. EVs and PHEVs save energy due to the employment of reverse regenerating braking, during the deceleration cycle. This recuperated energy can be proficiently stored in batteries and/or ultra-capacitors. In general, the design of an intelligent control strategy for coordinated power distribution is a critical issue for ultra-capacitor supported PHEV energy storage systems. Implementation of several control methods have been presented in related literature, with the goal of improving battery life and overall vehicle efficiency. The control objectives vary with respect to vehicle velocity, power demand, and state-of-charge of both the batteries and ultra-capacitors. Hence, an optimal control strategy design is a critical aspect of an all-electric/plug-in hybrid electric vehicle operational characteristic.
This thesis deals with the detailed analysis and novel hybrid controller design for bidirectional energy management solutions, using smart power electronic DC/DC converter solutions. More specifically, an intelligently designed novel digital control technique is presented for a 4-quadrant switched-capacitor Luo (4Q SC Luo) DC/DC converter. Features of voltage step-down, step-up, and bi-directional power flow are integrated into a single circuit. The novel control strategy enables simpler dynamics, compared to a standard buck converter with input filter, superior regulation capability, lower source current ripple, ease of control, and continuous input current waveform in buck and boost modes of operation. Furthermore, the proposed novel control strategy depicts high converter power density, high efficiency, and simple structure.