A study on the HBML inverter using the cascaded transformers

In this paper, an efficient switching pattern to equalize the size of transformer is proposed for a multi-level inverter using cascaded transformers. It bases on the prior selected harmonic elimination PWM (SHEPWM) method. Because the maximum magnetic flux imposed on each transformer becomes exactly equal each other, all transformers can be designed with the same size regardless of their position. Therefore, identical full-bridge inverter units can be utilized, the modularity can be more efficient and the manufacture can be easier