A Hybrid Control Strategy Based on Model Predictive Control Approach for the Rectifier Stage of Solid-State Transformer

This paper focuses on studying the Solid-State Transformer (SST) and proposing a control strategy for its input stage. The conventional low-frequency transformers suffer some drawbacks such as uncontrolled voltages and currents, high sensitivity to harmonics, low voltage quality in saturation conditions and so on. The solid-state transformer consists of several power electronic converter stages and as it is designed to be utilized as the power supply in electric train applications in this research, it is considered to be step-down and only has a DC output. Therefore, the studied configuration only consists of rectification and DC-DC step-down conversion stages. The main contribution of this paper is to propose a hybrid method based upon the Model Predictive Control (MPC) approach in order to balance the capacitor voltages and also control the power factor of input rectifier. The suggested strategy provides some advantages compared to other methods such as simple algorithm, significantly lower computational burden (compared to the conventional predictive control method) and simultaneous control of the input current, power factor and also the output voltage. Finally, the feasibility of the proposed method is verified through conducting simulations in the MATLAB/Simulink environment.