Direct Synthesis Based Centralized PI Controller Design for Single Inductor Multioutput (SIMO) Buck Converter to Alleviate Cross Regulation

The main control challenge in the single inductor multioutput buck converter (SIMOBC) is the cross-regulation in the output voltages. To alleviate this cross-regulation, a centralized frequency domain PI controller design methodology based on direct synthesis for SIMOBC is presented. In this method, the controller parameter is evaluated by comparing the closed loop transfer function (CLTF) matrix of the SIMOBC model with the desired CLTF matrix. The desired CLTF is considered as a diagonal matrix to achieve no cross-regulation in the output voltages. The diagonal element of the desired CLTF matrix is selected to have the desired closed-loop dynamics of the individual output of the SIMOBC. The controller is further approximated as a PI controller by frequency response matching at low frequency point. To validate the proposal, two cases are considered, i.e., single inductor dual output and single inductor three output buck converter. The performance of the proposed scheme is investigated using both MATLAB simulations and hardware experiments involving both the converters. Results verify the effectiveness of the proposed control scheme.