A novel buck-boost AC-AC converter with inverting and non-inverting operation and no commutation problem

In this paper, a new type of ac-ac converter is proposed which can operate as traditional non-inverting buck and boost converter or inverting buck-boost converter. The proposed converter is immune from shorting of voltage source even when all switches are turned on simultaneously, and therefore, PWM switching dead-times are eliminated to produce high quality output waveform. Owning to the benefit that only two switches are switching at high frequency, the switching losses are reduced which allow the high frequency operation with reduced passive filter requirements. Compared to the traditional non-inverting buck and boost ac-ac converter which can only step-down or step-up the input voltage respectively, the proposed topology has both step-down and step-up operations with or without voltage inversion. Moreover, while operating as non-inverting buck and boost converter, it has lower switch voltage stresses, lower inductor current stress and ripple current than the traditional inverting buck-boost ac-ac converter. A detailed topology analysis is presented followed by experimental results to prove the advantages of the proposed converter.