The Art of Voltage Boosting Part I: Boosting Switched Capacitor Converter Part II: Hybrid Boosting Converters
Voltage boosting is required in many energy conversion applications, ranging from front-end solar energy system to Medium-Voltage DC (MVDC)-grid system, and from headlamp ballast of automobile to fuel cell powered system. This dissertation is dedicated to the development of voltage boosting technology. New circuits were found both in switched capacitor converters and inductor-based power converters. The former has the potential of full integration while the latter has combined the merits of conventional magnetic components and switched capacitor stages, leading to a new hybrid converter category. These contributions are captured in two major parts respectively: The first part discusses the switched capacitor converters and new discovery in voltage boosting technology as well as modeling technique. The second part introduces a number of new topologies and extensions in hybrid boosting converters.
Switched Capacitor Converter (SCC) is a special branch of power electronics converters which is composed of capacitors and switches without the participation of inductors/transformers. It potentially has lower electromagnetic interference (EMI), lighter weight, lower cost, higher energy density, and the promise for full integration.
In this part, a family of "Two-switch Boosting Switched-capacitor Converters (TBSC)" is introduced, which distinguishes itself from the prior arts by its symmetrical interleaved operation, reduced output ripple, low yet even voltage stress on components, and systematic expandability. Along with the topologies, a modeling technique based on charge-balance transient-calculation is formulated, which provokes the converter regulation method through duty cycle and frequency adjustment. The design guideline for high efficient TBSC is provided and regulation under high power condition is explored.
In addition, an enhanced accurate modeling technique considering the output capacitor effect is developed for simple two-phase SC converters.
Built upon the momentum of the "Two-switch Boosting Switched-capacitor Converters (TBSC)" circuit structure, another family of Hybrid Boosting Converters (HBC) is developed, featuring wide regulation range, symmetrical configuration, low component voltage stress, small output voltage ripple, and expandable structure. It integrates the inductive switching cores of various functionalities and control strategies with Bipolar Voltage Multiplier (BVM), resulting in the new breed of hybrid converters: Hybrid Boosting Converters (HBC). The proposed HBC family includes the basic HBC, symmetrical HBC, Isolated HBC, and tapped inductor HBC, all of which are analyzed in details and design considerations are provided.
In addition, the 3D DC-DC converter concept for high power application, inverter configuration and DC micro-grid based on HBC converters are developed.
The proposed HBCs are applicable in many areas such HID lamp driver, X-ray system, ion pumps, front-end photovoltaic energy system, and energy storage systems.