A novel control strategy for AC/AC converters with high frequency AC link

In recent years, many researches have been done on AC/AC converters with high frequency AC link to make the equipment cheaper, lighter and smaller. And many problems have been solved such as zero voltage switching, low total harmonic distortion of the output voltage, low audio noise etc. However, it's hard to realize no static error tracking when the output voltage is alternate, and double-loop PI regulator is difficult to be used. In this paper, a novel control strategy based on single-phase dq coordinate transformation and feed-forward harmonic compensation is employed. As a result, ac voltage output with arbitrary amplitude and no static error tracking can be realized. While the advantages which proposed above will be retained. The converters' averaging model, and the output characteristic curve are given. The theoretical analysis and simulation results of 5kVA 220V±10% 50Hz/220V±1% 50Hz ac prototype have shown the effectiveness of the proposed control strategy when applying to power line conditioning and it also has other advantages, such as good dynamic characteristics and strong adaptability to various loads.