{'fraction_non_alphanumeric': 0.023255813953488372, 'fraction_numerical': 0.0, 'mean_word_length': 5.455555555555556, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Improved Control of Symmetrical Half-Bridge based Second-Order Harmonic Active Filters

DC systems connected to single-phase AC/DC converters are subject to a second-order harmonic ripple affecting the DC-bus voltage. Such ripple can be neutralized through an active filter circuit. This paper presents an improved control algorithm for a symmetrical half-bridge based active filter architecture. Contrarily to standard control approaches, the proposed solution does not require any external measurement other than the voltages and current internal to the active filter itself. This makes the analyzed active filter architecture suitable for a plug-and-play solution, meaning that it can be connected to the DC-bus terminals of a pre-existing system without any additional modification. The proposed control algorithm is based on multiple cascaded feedback loops, and the frequency and phase synchronization with the second-order harmonic component to be eliminated is based on an internally developed Phase-Locked-Loop (PLL). The developed approach has been numerically tested and validated in different operating conditions, showing satisfactory performances.