Design of a simple modular active power electronic transformer

The current project was originally initiated by the marine industry, where bulky low-frequency transformers have become a growing problem and the need for a more flexible solution is growing. The active power electronic transformer (APET) is likely to be the most suitable candidate. Modular power electronic building blocks (PEBB) enable complex power electronics systems to be built and reconfigured quickly and reliably. As a result, reduced costs, losses, weight, size and less engineering effort could be achieved. In this paper a new type of the PEBB for the APET is proposed. The input and output stages were constructed from the half-bridge sub-modules of the modular multilevel converter while the isolation stage consists of the conventional dual half-bridge. To balance the voltage of input capacitors a simple control algorithm was proposed. The performance of the system was verified by computer simulations using PSIM simulation software. Finally, a 3D model of the demonstrator is presented.