Study on a New Topology of Power Electronic Transformer

Considering the development of electric vehicle (EV), a new topology of power electronic transformer ( PET) was proposed firstly. The proposed topology consists of three conversion stages:( 1) the input stage adopts MMC structure; ( 2) the dc/ dc converters in isolation stage adopt the connection mode of input serial output parallel;( 3) the output stage includes an inverter module and switchable power modules. The switchable power module can both output dc and ac. By changing the output of the switchable power module, the capacity of ac and dc can switch to use. This topology along with ac/ dc capacity switching technology has advantages of save PET capacity and improving capacity utilization. Then the control strategy of proposed topology was introduced. Finally, a simulation model was built in PSCAD simulation environment. Simulation results show that the proposed topology and its control strategy are feasible.