This paper reviews the possibility of implementing a buck-boost AC/AC converter with a changeable configuration, which ensures quasi-sinusoidal characteristics of source and load current. Load is made up of active and inductive components, with a parallel-connected smoothing capacitor whereas at the input stage a current-smoothing LC input filter is applied. The process is controlled by four bidirectional semiconductor switches, from which two are active in each of the operation modes. An explanation of electromagnetic processes in both of the operating modes is given, in order to show how the mathematical description of the circuit functionality is acquired. Computer simulation results are introduced as well, providing a comparison of calculated and simulated parameters at both the buck and boost operation cases.