Architecture Analysis of High Performance Capacitors (postprint)

Evolutionary increases in the demand on electrical power systems have resulted in the need to develop the next generation of compact, power dense, electrical systems utilizing robust and efficient high voltage power devices that are operable over an extended temperature range (-55°C to 250°C). In particular, there is a need to investigate novel capacitive architectures as a means to compliment recent advances in SiC power devices and high temperature magnetic and insulation materials. These advanced electrical components have enabled the demonstration of compact, high switch rate power system components that can operate at temperatures in excess of 200°C, but have been limited by current capacitor technology. Of concern with present state of the art capacitors are their volumetric energy density, dissipation factor, thermal stability, parasitic inductance, and failure mechanisms. A modeling and simulation capability will be described herein, which was used to investigate device architecture-electrical performance relationships for wound, collapsed, and stacked devices. Initially, a mathematical model is developed and utilized for both equivalent capacitor circuit analysis and device architecture field analysis, which were then used to identify factors (e.g., electrode, dielectric, contacts, etc.) that affect ESR, ESL, and capacitance. Additionally, finite element analysis of selected device architectures was accomplished to compare magnetic fields and thermal profiles predicted. The predicted electrical properties resulting from these analyses were then utilized as SPICE simulation input parameters to evaluate the performance of the different capacitors in a dc-dc boost converter model. Finally, modeling and simulation results are compared to empirical data sheet information and experimental data. The knowledge gained from this study provides insight into the key capacitor design and packaging parameters yielding optimized voltage, current, DF, and frequency characteristics for designated applications.