Current Tracking Control of Triple Active Bridge DC/DC Converter Under Varying DC-Bus Voltage Conditions

A triple active bridge (TAB) converter consisting of three full-bridge inverters and a three-winding transformer has been researched to improve its power conversion performance as a bi-directional isolated multiport converter. Previous research established a current control method using a decoupling system to solve the complex power transmission structure of the TAB converter. However, it is challenging to integrate voltage factors into the decoupling system because DC-bus voltages of the TAB converter are assumed to be constant. Active bridge control against voltage variations has become essential to achieving high-performance DC/DC power conversion systems using high-frequency transformers such as a TAB converter. This paper proposes a TAB converter control method, which is an expansion of the conventional method, to integrate the DC-bus voltage variation into the control model. Model predictive control is used to achieve tracking control by incorporating voltage variation factors into the control method using an established model structure as a basis for predictive calculations. Simulations were conducted to verify that the proposed method improves the output responses compared to the conventional methods when the DC-bus voltages change. Also, experiments using a prototype converter show that the proposed control method can achieve current tracking control during the voltage variation.