Proportional Resonant Control With Phase Correction for Stability and Dynamics Enhancement Under Low Carrier Ratio Conditions

Phase-corrected proportional resonant (PCPR) current controllers are mainly studied under high carrier ratio conditions. When applied to high-power converters with low carrier ratios, the system could be unstable or have poor dynamics without a proper parameter design. In order to illustrate both stability and dynamics to guide parameter design, bilateral Bode plots are tailored in this article that considers the correct negative jump direction at resonant frequencies. Then, this analysis tool verifies the feasibility of the phase correction angle set over 90°, especially under a carrier ratio below six. With the designed phase correction, the stability region of the carrier ratios is characterized as extending to the theoretical limit of one. Moreover, the resonant gain of PCPR is quantitatively designed considering the variation of carrier ratios by maximizing the bandwidth under guaranteed stability and margins. Finally, the simulations and experiments verify the enlarged stability region with the phase correction and improved dynamic performance with the proposed resonant gain design method.