Abstract

Future computer and telecommunication power distribution systems require the power source to be high frequency ac type and be combined with line current Power Factor Correction that satisfies IEC 1000-3-2 standard. In addition, low power applications require high efficiency, high power density and cost effectiveness. This thesis provides a solution to low power ac-ac inverter for the future computer and telecommunication power distribution systems, which complies with the above requirements. The proposed high frequency ac-ac inverter operates under Zero Voltage Switching (ZVS) throughout the whole range of the line voltage and load. Hence, high efficiency can be realized under high switching frequency. A unified controller is introduced in the proposed ac-ac inverter to control the dc-ac stage and the PFC stage at the same time. The controller is simple and the DC bus voltage can be well limited for A line and load conditions. Hence, cost effectiveness can be realized. In the thesis, two types of PFC stage converters (Boost and Buckboost) are presented to compare the performance of the ac-ac inverter. Principle of operation and steady state analysis of the proposed topology are given. Performance characteristics, design procedures and computer simulation results are presented to guide the design. Experimental results from a prototype of 100kHz, 30V ac /250W output, 90-265V ac input, are presented to confirm the analysis and performance of the proposed ac-ac inverter.