Analysis, design and implementation of a generalized step-up/step-down solid state transformer using PWM switching

The solid state transformer has many advantages over the conventional transformer, the most important of which is superior line and load regulation under transient conditions and an electronically adjustable turns ratio.;The solid state transformer is based on Buck-Boost converter topology and uses pulse width modulation (PWM) switch-mode technology. The solid state transformer accepts alternating current (AC) input voltage and delivers regulated AC output voltage by using bi-directional switches so that the transformer achieves bi-directional energy transfer. It is also capable of step-up/step-down performance. Theoretical analysis and control loop design are presented. A prototype solid state transformer was implemented for 1kW power performance. Experimental results of the transformer and hardware implementation issues are also discussed and promise the advantages of line and load regulation in the closed loop system.