A Five-Switch Single-Phase Buck-Boost AC-AC Converter with Inherent Commutation and Continuous Input Current

In this paper, a five-switch single-phase buckboost AC-AC converter with inherent commutation and continuous input current is proposed. The proposed converter only requires five switches, which sets it apart from other nonisolated AC-AC buck-boost converters that have been presented so far. Additionally, the number of energy storage elements in this converter has been reduced. Also, the output frequency can be changed as a multiple or fraction of the input frequency by symmetric non-inverting and inverting operations of the proposed converter. The converter solves the commutation problem without the need for snubber circuits or safe commutation methods. It achieves inherent commutation without dividing the circuit structure into positive and negative switching cells. Another advantage of this converter is that it maintains a continuous input current and does not require an input LC filter. Comparing and analyzing the total switching devices power (SDP) index and component volume, it can be concluded that this converter improves power density while reducing switching losses, size, and cost. The operating principle of the converter is explained through various operational modes, and the relevant relationships are calculated. The paper provides a theoretical analysis and includes experimental validations conducted on a laboratory prototype with Po = 260W and fs = 50kHz.