Polar Coordinate Decoupling Power Flow Control for Triple Active Bridge Converter

A triple active bridge converter can play a role of energy management in dc grids and help to construct them including distributed power systems and loads. However, the control system of a triple active bridge converter is a 2-input 2-output system. Therefore, a decoupling control is necessary. In a conventional control method, the decoupling matrix is designed as an inverse of the small signal transfer function matrix. However, the transfer function matrix is developed by approximation, causing the errors in the decoupling matrix. There has a little interference by using this conventional decoupling control method. This paper proposes a novel decoupling power flow control method for triple active bridge converters. The polar coordinate directly determines the phase shifts between the ports by utilizing the amplitude and the phase angle represented by the sum and the difference of transmission powers. This method is expected to get faster responses by using feedforward control and to achieve precise decoupling. The experimental results validate these expectations.