A nonlinear control strategy for hybrid active power filter

To improve the harmonic current compensation performance of the active power filter (APF) and reduce its active part ratting, a hybrid active power filter (HAPF) of a lower dc bus voltage is studied, which composes of a passive filter and an active power filter in series. On the basis of mathematical model which includes both the passive filter and an active power filter, a Lyapunov function is constructed, and then an appropriate control law is presented to make its leading function negative definite, so that the steady tracking for harmonic current is realized. The turning range and the optimization goal of the control gain are also given by derivation from the robustness and tracking performance perspective. At last, the simulation analysis and experiment verify the feasibility and the superiority of the proposed control strategy.