Capacitor-Less Buck Converter Using Integrated Planar Electromagnetic Components

Electric vehicles (EVs) encounter reliability challenges primarily originating from the reliability of semiconductor devices and dc-link capacitors commonly used in onboard chargers. Capacitors are especially prone to wear-out mechanisms and failure modes, leading to increased monitoring and replacement costs for these systems. Traditionally, stray capacitance in power electronics has been viewed as unavoidable and undesirable. However, this paper challenges this conventional view by advocating for the integration of stray capacitance as intrinsic components within the system’s topology, particularly in dc-dc converters. By utilizing alternative materials with high dielectric constants, such as calcium copper titanate (CCTO), specific parasitic components, notably inter capacitance, are intentionally enhanced. This innovative approach reduces the reliance on external discrete capacitors and facilitates the development of highly reliable converters for EVs. To demonstrate this concept, a dc-dc buck converter, typically employed on the low voltage side of EVs to supply low voltage loads, is presented along with a comprehensive circuit model, validated through finite element analysis. The robustness of the proposed circuit model is verified through two crucial tests: firstly, varying the duty cycle from 50% to 90%, and secondly, examining the load transient response by adjusting the load from 10Ω to 20Ω. The results from both tests affirm the accuracy of the proposed circuit model and its consistency with finite element analysis outcomes. Specifically, the suggested converter holds promise for EV applications in electric power transmission and serves as a reliable power supply for 12V electronics within the vehicle.