Hybrid Filters for High-Current Power Supplies Using Deadbeat and Repetitive Control

The paper examines the challenges of supplying high current coils in magnetically confined fusion generators. Such systems use power electronic converters traditionally supplied by grid-connected thyristor-based interfaces. Due to their Megawatt-scale pulsed-power operations, a decoupling storage system is often used. Recently, supercapacitor based storage systems emerged as a promising option. However, the harmonic distortions produced by the switching operation of power electronic converters require the use of passive filters. Due to the large currents (tens of kA) and low switching frequencies (around 1 kHz), their size and volume become a significant challenge. To reduce filter size, the paper proposes the inclusion of active filters on the DC supply side of high-current converters. Unlike conventional linefrequency applications, active filters must track higher frequency harmonics, thus a fast and accurate control system is needed. To this aim, a control approach combining deadbeat and repetitive algorithms, implemented on an industrialgrade microcontroller, is presented and validated through real time hardware in the loop tests. A volume and cost comparison with the traditional solution confirms the effectiveness of the proposed approach.