Research On Schemes To Improve The Power Inverter's Efficiency

In many important power electronics applications, such as: renewable energy generation, uninterrupted power supply, electric machine drive, active power filter, induction heater, etc. the performance of power inverter is quite crucial. As the requirements for higher power density and output performance, how to keep the inverter at a relative higher efficiency at higher switching frequency is becoming more and more important.This thesis first builded up the loss model of inverter with different modulation methods. According to the loss calculation and verification results, the way to further increase inverter's efficiency is analyzed.Then the loss model is applied to other types of inverter topologies, include Diode Neutral Point Clamped (DNPC) three-level, and Auxiliary Resonant Commutated Pole (ARCP) soft-switching inverter topologies. The three-level and soft-switching inverters' efficiency advantage to traditional inverter is investigated, based on the loss and experimental evaluation. The comparisons of the three inverter topologies were made. Each topology's advantages and disadvantages were summarized.Moreover, this thesis analyzed the resonant process of ARCP soft-switching inverter, as well as the control strategies for auxiliary switches. Then a general resonant parameters selection method was indicated. The fixed and variable timing control strategies used for the auxiliary switches were analyzed. And then a novel divided-fixed timing control method was proposed. Comparisons of this three control methods' current stress in circuit, loss distribution, and inverter efficiency were introduced.Finally, the inverter's efficiency improvement by SiC freewheel diodes and high speed IGBT were researched, and comparisons of different power semiconductor devices' combinations are made.