A New Dual-Buck Five-level Inverter with Coupled Inductors

• Main Authors: Ming-KaiChuang, 莊銘凱
• Other Authors: Hong-Tzer Yang
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/30675287382179477219

碩士 === 國立成功大學 === 電機工程學系 === 102 === The input capacitors used in conventional multilevel inverters commonly experience a voltage-imbalance problem. Accordingly, the thesis proposes a new dual-buck inverter with coupled inductors to realize a five-level inverter, consisting of single input capacitor, a dual-buck module, and a full-bridge module. With the coupled inductors, the inverter ensures an improved sinusoidal voltage to the load. In addition, the dual-buck module enhances system reliability by solving the shoot-through problem existing in conventional circuits. The proposed dual-buck module, comprising two diodes and two power switches, generates a three-level voltage which is then converted to a five-level sinusoidal voltage by the full-bridge module. A modulation method is developed accordingly for the proposed inverter with various switching patterns analyzed. Via the presented modulation method, no dc offset exists in the magnetizing inductor currents, and problems of core saturation can thus be avoided. The performance of the proposed converter is evaluated by the implemented prototype circuit with an input dc voltage of 380 V, an output ac voltage of 220 Vrms, and an input power of 1.5 kW. The experimental results show that the output voltage total harmonic distortion (THD) of 1.2 % at full load condition and a highest efficiency of 94.7% have been achieved to validate the feasibility and effectiveness of the proposed multilevel inverter.