High Power Density and High Temperature Converter Design for Transportation Applications

The continual development of high-power-density power electronic converters is driven particularly by modern transportation applications like electrical vehicles and more electric aircraft where the space and carrier capability is limited. However, there are several challenges related to transportation applications such as fault tolerance for safety concern, high temperature operation in extreme environments and more strict electromagnetic compatibility requirement. These challenges will increase difficulties for more electrical system adoption in the transportation applications.;In this dissertation, comprehensive methodologies including more efficient energy storage solution, better power electronics devices capability, better packaging performance and more compact EMI filter design are analyzed and proposed for the goal of high power density converter design in transportation applications.;The dissertation is divided into five sections. Chapter 1 describes the motivation and objective of this research. After examining the surveyed results from the literature, the challenges in this area of research are addressed. Chapter 2 presents the energy storage capacitor size reduction by using an active ripple energy storage method in fault tolerance transportation applications. With the minimum ripple energy storage requirement, the feasibility of the capacitor volume reduction is verified. Then, a bidirectional buck-boost converter as the ripple energy storage circuit is proposed which can effectively reduce the capacitor size. Meanwhile, the feed forward control method is implemented with the active circuit. Chapter 3 demonstrates the high temperature converter design in transportation applications. A novel hybrid structure packaging method is proposed to utilize the benefits of both wirebond structure and planar structure. Detailed analysis was conducted for the hybrid structure packaging in terms of parasitic reduction and thermal reliability. Then, a detailed high temperature converter design procedure is proposed together with a multi-chip power module packaged in hybrid structure. The whole converter is capable of working in harsh environment. Chapter 4 shows a more compact EMI filter design procedure including both transfer gain and insertion gain analysis. With the transfer gain analysis, both the low frequency and high frequency attenuation requirement is considered and an optimum number of stages can be derived in terms of minimum volume. Since the EMI noise source and load impedance cannot be treated as ideal cases in the real applications, a frequency domain model based on the impedance measurement is utilized to provide EMI noise attenuation prediction. Mask impedance can then be employed to linearize the EMI noise source impedance. After this, the magnetic component near-field coupling phenomenon is studied. Displacement current influence to the near field distribution is discovered and analyzed in detail. Finally, Chapter 5 presents the summary and conclusions.