Integrated Inductors and Capacitors with Co-Located Electric and Magnetic Fields

Abstract

Passive components such as inductors and capacitors are fundamental components needed in all power electronics converters, and in many designs, they comprise a significant portion of the total weight and volume of the converter. As more renewable energy is added to the grid, and hybrid and electric powertrains become more common in the automotive industry, power electronic systems to convert energy between different types of sources and loads will be of increasing importance. In order to improve upon power electronic conversion circuits, this thesis presents an innovative method for decreasing the cost, size, and weight of power electronic converters by integrating the electric field of a capacitor with the magnetic field of an inductor into a common volume. In this new method, the parallel plates of a stacked or rolled film capacitor are also utilized as the permeable laminations of the inductor core. This two terminal capacitor can then be wound with a separate two terminal inductor winding. This device is dissimilar from existing integration techniques, which integrate the terminals and arrange the discrete electric and magnetic fields in close proximity to each other. The proposed device improves upon existing technologies by allowing the possibility of volume reduction, weight reduction, and packaging efficiencies, while keeping the two inductor and two capacitor terminals galvanically isolated. The proposed device is analytically modeled and the fields in the core are analyzed. While the terminals are galvanically isolated, cross coupling of the fields is examined. Two different proof-of-concept prototypes are constructed and tested to verify the analytical models. One of the devices is tested in boost converter circuit application. A basic design procedure is developed for the proposed device that allows the use of a volume minimization routine to reduce the overall size. Several tradeoffs and material and geometry issues are discussed. Finally, several candidate manufacturing processes are evaluated.