An observer-based digital control system for individually management of active and reactive power of dual-active-bridge DC/DC converter

This paper proposes an observer-based digital control system to manage active and reactive powers in a Dual-Active-Bridge converter. Since they are proportional to the direct and the quadrature components of the transferred current, Id and Iq, respectively, the power management is realized by regulating the two current components. An observer is designed to estimate them from the feedback voltage and the average absolute value of the transferred current. Since all the feedback signals for the observer are DC quantities, the sampling speed is not necessary to be very high. A digital controller is then synthesized to regulate Id and Iq at desired values. In the control system, the bridge shift angle is used to handle Iq, meanwhile the switching frequency is variable to manipulate Id. The current command for Id is calculated from the desired active power, meanwhile, by assigning a positive value for Iq control loop, soft turn on is easily achieved. The performance of the observer as well as the digital control system is validated by a laboratory-scale experiment system