Development of a nonlinear control strategy for the DC power transferring system

This paper presents a detailed control strategy to a PWM bidirectional DC-DC transferring system designed for high voltage, high power applications. The objective is to realize precise bidirectional power flow control between two DC grids, where the half bridge topology is adopted for the connection between them. By using the averaging technique, the system´s nonlinear average model is derived, based on which the nonlinear control algorithm is proposed, to realize the current control. The proposed circuit and control strategies are simulated using SimPowerSystems and a comprehensive synthesis of the control algorithms is conducted, from the viewpoint of rapidity, robustness and system cost. It is verified that the proposed nonlinear control algorithm has a fast response, competent disturbance rejection ability and low cost. Although the structure studied here is the half bridge bidirectional converter, however, the controller design methods and the relative conclusions can be promoted to any type of structure in power transferring systems.