Low-harmonic resonant CLL-type AC/DC converter

A new resonant AC/DC converter is presented. It has been shown that the ser ies parallel CLL topology is particularly useful in resonant rectifier appl ications. The transformer may be designed to replace one or both the induct ances used in the resonant network. The converter is operated only in the l agging power factor mode, dispensing with the need of an external device sn ubber. Such a converter is analysed and simulation results are obtained by using MATLAB. Two new control strategies are proposed. Both control schemes are implemented and compared. Scheme 1 requires reduced hardware and no cu rrent sensor, but scheme 2 uses a current sensor and an additional PI contr oller. Scheme 2 performs better than scheme 1 in terms of total harmonic di stortion (THD) of the converter input current. A laboratory prototype has b een fabricated and excellent performances have been confirmed.