{'fraction_non_alphanumeric': 0.02375, 'fraction_numerical': 0.0, 'mean_word_length': 5.114503816793893, '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}}
Free Oscillation Analysis of Multi-coil MC-WPT System

In this paper, a second-order time domain model of multi-coils magnetic coupling wireless power Transfer (MC-WPT) system is established. The undamped free oscillation and damped free oscillation of the MC-WPT system are studied. It is proved that the undamped free oscillation frequencies of the system are the natural frequency and the damped free oscillation frequencies are equal to resonance frequencies. Calculation method of the natural frequencies and resonance frequencies of any multi-coil system is presented. The damping state of the system is divided, and theoretical analysis shows that n-coil system has at most n natural frequencies and resonant frequencies. Finally, the correctness of the theory is verified through experiments.