A robust two-dimensional deadbeat current control method by using adaptive line enhancer for active power filter

An effective system control method using a three-phase current-source PWM converter with a finite time settling controller for active power filters (APF) is presented. In a shunt-type configuration, the APF is controlled such that the current drawn by the APF from utility is equal to the current harmonics and reactive current required for the load. To attain the time-optimal response of the APF supply current, a 2D deadbeat control scheme is applied to the APF current control. Furthermore, in order to cancel both the delay in the 2D deadbeat control scheme and the one in DSP control strategy, an adaptive line enhancer (ALE) is introduced for the purpose of predicting the desired value of three sampling periods. ALE also provides the robustness to the deadbeat control system. Due to ALE the settling time in a transient state is made short. On the other hand, the steady state total harmonic distortion ratio,of source currents can be reduced comparable to the case of ideal identification of the controlled system. The experimental results obtained from a DSP-based APF are reported. The compensating ability of this APF is very good in terms of accuracy and responsiveness.