An Adaptive Droop Control Scheme Based on Sliding Mode Control for Parallel Buck Converters in Low-Voltage DC Microgrids

Droop control is a widely used method in DC microgrid to solve the problem of the current sharing errors. However, it is difficult to trade off the current sharing errors and bus voltage deviation in parallel converters microgrids. This paper designs an improved droop control scheme based on adaptive droop control and sliding mode control (SMC). The droop coefficient is adjusted adaptively by proportional integral (PI) control loop to minimize the current sharing errors and the bus voltage deviation is compensated adaptively by another PI control loop, through the acquisition of the bus voltage and current. Moreover, the SMC is used to control the output voltage of each converter instantaneously. Finally, a simulation model of three parallel buck converters is built based on MATLAB/Simulink, which verifies the feasibility and effectiveness of the designed scheme in this paper. This scheme only needs power lines to transmit data, which reduces the communication burden. It is suitable and reliable for small and medium-sized DC microgrid.