Current balancing in Parallel Connected Buck Converter

Abstract

Dependency on high-power renewable energy sources such as photovoltaic system increases the need for parallel-connected converters. The main challenge in the parallel-connected converter is balancing the electrical current among the converter units. In this paper, a parallel-connected buck converter designed for high-power applications. Pulse width modulation is used as the converter switching technique. Using high-frequency pulse width modulation simplifies the control of the converter output voltage. In addition, the high-frequency pulse width modulation reduces the size of the passive filter needed to filter the ripple from the output signal.     Two units of buck converter are connected in parallel to study the current sharing among them.  A control technique using a proportional–integral controller PI controller is used to balance the current between the two buck converters. The tuning of the PI controller is made by using the Ziegler Nucleus method. Closed-loop and open-loop control systems were tested and simulated in SIMULINK.

Keywords- Buck converter; closed-loop control; current balancing;parallel connected converter.