Mismatched Disturbance Compensation Enhanced Robust H$_\infty$ Control for the DC-DC Boost Converter Feeding Constant Power Loads

A new control scheme to enhance the robustness and disturbance rejection ability of a DC-DC boost converter feeding constant power loads (CPLs) is proposed in this paper via introducing mismatched disturbance compensation into the robust ${H_\infty}$ control. In cascaded DC power converter systems, the load side converters, when tightly controlled, behave as CPLs for their source side converters, where the nonlinearities could result in severe instability. Besides, for power converters in DC microgrids, both the uncertainties/disturbances and the unpredictable load access could result in severe challenges to achieving higher control performance. In particular, the unknown CPLs must be considered as part of disturbances that form the so-called mismatched disturbances. To counteract these negative factors, a practical exact feedback linearization method is used to transform the control problem of a nonlinear system into that of a linear system, and the compensation of mismatched uncertainties/disturbances is introduced into the robust ${H_\infty}$ control design. Moreover, sufficient conditions to ensure the asymptotic stability and robustness of system are established. Both simulation and experimental results confirm the efficiency.