Research On Key Aspects In Integrated Power Electronics Modules For High Power Applications

In high power applications, the structures and topologies are not as many as that in the low power applications. The main converters used usually are with the same structure, therefore it's possible to use the standardized modules to built the main circuit. In the industry, it already becomes a trend to develop basic modules for high power applications. This dissertation mainly focuses on some key issues in development of High Power Integrated Power Electronics Module (HVIPEM).The multilevel technology has been employed in the high power application for many years, such as in STATCOM, UPFC, DVR, and APF etc. The structure of the multilevel topology has the character of "building block", and has the potential to be built with several basic IPEMs. From the point of view of the generalized multilevel inverter topology, the dissertation analyzes various topologies in multilevel applications, and gets two main methods to form a multilevel converter: combination and simplification. These topologies formed by combination are suit for design with basic IPEMs.In this dissertation, a new cascaded multilevel converter with self voltage balancing is proposed. With this new topology, only one DC source is needed for multiple outputs. The voltage across the capacitor in each cascaded cell can be balanced without special control, and independent of the load type. Compared to the traditional multilevel topologies, the new one has advantages in lower cost, simpler control and better performance in low modulation. The new topology also can be extended for DC-DC applications.A new 1 kW 42/14 V flying capacitor converter is proposed and designed for 42 V automotive system, the proposed converter has no requirement for magnetic components. The main circuit of the DC-DC converter is analyzed and its control scheme is presented in this dissertation. Besides, a new design method for DC-DC converter with flying capacitor technology is presented in this dissertation. The new method can reduce the high pulse current which usually causes serious problem in traditional flying capacitor DC-DC converters. The experimental results show the new converter can achieve a peak efficiency of 98% and 96% at full load. The experimental results verified the analysis and demonstrate the advantages.Two HVIPEMs were successfully designed in this dissertation: one three-level 50 kVA inverter module and one 1.5 MVA integrated inverter module. Several key issues were discussed in the development of the HVIPEMs. With software simulation and experiment test, the dissertation compared different bus bar types and preferred the laminated bus bar. An optimized bus bar and an optimized water cooled heatsink were designed for the 1.5 MVA inverter module. Both 50 kVA and 1.5 MVA inverter modules have the capability to be extended in the cascaded system for higher voltage and higher power level. The dissertation discusses various applications with the designed module, such as electric traction, Unified Power Quality Conditioner (UPQC), and wind turbine.