Direct duty ratio control of connected converter in DC microgrid

Abstract

A direct duty ratio control (DDRC) method is proposed in this paper. The method uses the change of DC bus voltage in each control period to predict the inductor current. To make the DC bus voltage work in a definite range, a linear control relationship between the DC bus voltage and the inductance current is established. In order to improve the control precision and dynamic response, the duty ratio of the converter is deduced and predicted by the change of inductor current. In addition, the dynamic performance of the system under impulse disturbance is improved by adding virtual capacitor to the voltage loop and the parameter design of virtual capacitor is provided. Finally, the simulated setup of single-phase inverter in DC microgrid is built and the effectiveness of this method is verified by simulation.