Modelling and Control of Single Phase VIENNA Rectifier

Compared with the traditional two-level or three-level unidirectional rectifier, VIENNA rectifier is the favorite choice for its advantages such as only half numbers of the switches, simple structure, high power density and ability to realize unity power factor with appropriate control strategy. However, it's difficult to analyze the system and design the controller since the model of the rectifier is non-linear. Using small-signal model can transfer the non-linear model to a linear no-time varying model. In this paper, average current mode control is used in the decoupled three-phase four-wire VIENNA converter, and neutral-point potential balance is included. Small signal model based on control strategy of single phase VIENNA rectifier is bulit. The transfer functions are derived and their Bode plots are drawn. Double PI controllers for outer voltage loop and inner current loop are designed with the help of the transfer functions, and the simulation result proves the validity of the model.