Development and Analysis of Snubber Networks for the Primary Side Transistors of a Three-Phase, Galvanically Isolated, Single Stage Push-Pull Pulse Rectifier

Inhalt:
This paper presents an AC/DC front-end converter for direct, galvanically isolated integration into industrial and building DC distribution grids. A key design challenge lies in the parasitic leakage inductances of the transformer, which cause high voltage spikes when the transistors are turned off. These overvoltages threaten the integrity of the MOSFETs and the overall system reliability. To address this, a snubber network is developed to safely redirect the leakage energy and minimize voltage stress. The snubber is dimensioned to ensure both effective protection and low power loss. Design equations are derived and validated through PLECS simulations that reflect realistic switching behavior. A MATLAB based analytical model supports a detailed power loss analysis. These results form the basis for the optimized snubber design. Hardware implementation on a dedicated PCB and subsequent measurements confirm the simulation outcomes and demonstrate reduced drain-source overshoot. As a result, the electrical stress on the MOSFETs is lowered, which extends their service life. The proposed converter thus enhances the robustness and reliability of modern DC grid infrastructures and forms a scalable foundation for future extensions such as BiRectifier operation for bidirectional energy transfer and modular power architectures.