The main objective of conventional SMR (i.e. shown in Fig.1) is to eliminate these problems so as to maintain unity pf, sinusoidal input current, constant dc voltage and restricted harmonic distortion based on IEEE std. To avoid the separate operation for discontinuous current mode (DCM) and continuous current mode (CCM), a mixed-mode operation  is proposed for wide-range of load variation. Since the ripple content on output capacitor voltage and harmonic contents in input ac current are prime concern, the authors  presented a robust technique to get rid of these problems.
Pradhan, R. N.
"A Modified Switch-Mode Rectifier for Wide Range of Load Variations,"
International Journal of Power System Operation and Energy Management: Vol. 2:
1, Article 7.
Available at: https://www.interscience.in/ijpsoem/vol2/iss1/7