Small-Signal Model of the Five-Level Unidirectional T-Rectifier

In this paper, a small signal model is proposed for the new unidirectional three-phase T-type rectifier topology known as five-level T-Rectifier (5L T-RECT). The proposed model is obtained starting from the large signal analytical representation of the 5L T-RECT configuration. The derived equations have been simplified using the synchronous reference frame transformation; to this purpose, the average values over the fundamental period T₀ are considered for the input phase voltages. After that, the converter steady-state and dynamic models are derived by means of the local linearization around the desired operating point. The transfer functions related to the inputs and outputs of the system are, therefore, obtained and depicted. The achieved 5L T-RECT model has been first verified using the linear analysis tool in the _MATLAB/Simulink environment starting from the detailed switching model. Theoretical results exhibit a very good accuracy between the small-signal, the large-signal, and the switching models. Then, experimental activity is depicted to further validate the proposed small-signal model.