Five-level diode-clamped active power filter using voltage space vector-based indirect current and predictive harmonic control

This study presents an active power filter (APF) based on diode-clamped multilevel circuits with auxiliary dc-link voltage balancing circuits and harmonic compensation control. The control algorithm is composed of indirect current loop for active and reactive power control, predictive current loop for harmonic filtering control and independent control for auxiliary balancing circuits. Among these modules, the indirect current along with the predictive current control will generate a combined voltage reference to the module of space vector pulse-width modulation, which could output optimal modulation signals to the voltage control of a diode-clamped multilevel converter. Comparing with traditional dc control for two-level APF, this system takes advantages of indirect current control and multilevel circuits, including improvement in waveform quality, increase in system power rate and reduction in voltage stress and switching frequency on power semiconductors. Simulation and experimental results validate the effective control of the presented system.