An AC Z-Source Converter Based on Gamma Structure With Safe-Commutation Strategy

This paper proposes a novel single-phase ac-ac Z-source converter based on the Γ-structure. The proposed converter uses a coupled transformer to produce the required gain. The obtained gain can be tuned by varying the turn ratio γ
_Γ
of the transformer within the narrow range of 1 <; γ
_Γ
<; 2. Also, the gain factor increases with decrease of the transformer turns ratio, γ
_Γ
. Small transformer turn ratio results in more practical topology in some voltage gains. It makes the transformer design easier and reduces construction cost. Also, in the proposed topology, the input and output voltages share the same ground. In order to avoid voltage and current spikes on the switches, a commutation strategy is proposed and safe commutation is achieved without using a snubber circuit. The operating principles and steady-state analyses are presented to verify the operational concept of the proposed topology. Also, experimental results are given to verify the validation of the proposed converter.