Digital Control of a Shunt Hybrid Power Filter Adopting a Nonlinear Control Approach

This paper proposes a nonlinear derivative-less control approach for controlling a three-phase shunt hybrid power filter (SHPF). The dynamic model of the SHPF system is first elaborated in the stationary frame and then transformed into a “dq” reference frame. The control system is divided into two separate loops, namely the two current dynamics inner loop and the dc voltage dynamic outer loop. The exact feedback linearization technique is used to decouple the inner loop variables. Proportional-integral controllers are utilized to control the SHPF input currents and dc-bus voltage. The proposed nonlinear control is first simulated and then validated on a 2.5-kVA laboratory prototype supported by the DS 1104 digital real-time controller board of dSPACE. Satisfactory results, such as low-ac-current total harmonic distortion, fast step response, and high robustness under load variation, are obtained. Significantly high correlation between the experimental results and the theoretical model, implemented with SIMULINK/Matlab, is obtained.