Adaptive Nonlinear Control of Three-Phase Series Active Power Filters with Magnetic Saturation

The problem of controlling three-phase series active power filters (series APF) is addressed in the presence of nonlinear loads. In previous works, the control design for series APF is generally based on standard models that assume the involved magnetic coil to be linear. In reality, the magnetic characteristics of these components are nonlinear. In this paper, a new model for series APF load system, taking into account for the nonlinearity of coil characteristics, is developed. Based on the new model, a nonlinear adaptive controller is developed, using the backstepping design. The control objectives is twofold: (i) compensating for the harmonic and disturbed voltages components at the point of common coupling, this objective is referred to network voltage quality; and (ii) regulating the inverter DC capacitor voltage. Moreover, the controller is made adaptive for compensating the uncertainty on the switching loss power. The performances of the proposed adaptive controller are formally analyzed using tools from the Lyapunov stability and average theory. The supremacy of the proposed controller with respect to standard control solution is illustrated through simulation.