{'fraction_non_alphanumeric': 0.01632302405498282, 'fraction_numerical': 0.0, 'mean_word_length': 5.036269430051814, '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}}
The Multiple Degree of Freedom based Neutral Point Potential Control of Three Level Neutral Point Clamped Converters

Although the virtual space PWM and the dual wave modulation (DWM) method can eliminate the low frequency neutral point potential (NPP) fluctuation, which appears in some NPP control based on the nearest three vector PWM essentially, they will increase the switching frequency and fade the control ability of the NPP drift problem. In this paper, a novel multiple degree of freedom based NPP control with the strong control ability of low frequency NPP fluctuation and NPP drift problem is proposed for three level converter. The traditional DWM method sacrifices many control domains of neutral point current (io) to keep io zero, by setting the zero sequence voltage to an appropriate value. On the contrary, the proposed method introduces three degree of freedom to control the NPP, which makes it have the largest NPP control domains. The comparison on the control domains of io for DMW method and proposed method is discussed at first. Then, some simulation are also carried out to verify the correctness and effectiveness of proposed method.