Distributed control strategy for parallel-connected inverters. Sliding mode control approach and FPGA-based implementation

This work presents the design of a circular chain control (CCC or 3C) sliding-mode control scheme for a modular inverter system composed by N parallel-connected buck-based single inverters. AC output voltage regulation and balanced current-sharing among the single inverters is achieved by means of a set of switching surfaces and the corresponding sliding control laws. These control laws have been implemented by means of a FPGA. Additionally a power management strategy determining which inverters are turned on/off according to the power demand, has been also embedded into the FPGA. Simulation and experimental results for three parallel-connected inverters are provided to illustrate the features of the proposed design.