| Switching power converter combines the nonlinear power switches and somestorage elements and its working property performs time-domain piecewise linearcharacteristics, therefore behaving a strong nonlinear system. As a result, it will not onlyinject a large amount of harmonics into the power supplies, but also cause theemergence of abundant instabilities, such as sub-harmonic oscillation (fast scale),low-frequency oscillation (slow scale) and so on. These unexpected instabilities worsenthe working performance of the switching power converter systems. To this end, thispaper takes the peak-current mode controlled swtiching power converter as the researchsubject and focuses on an effective scheme, the proposed dynamic slope compensation(DSC) for suppressing the fast scale instabilities (for example sub-harmonic oscillation)with the typical DC/DC Buck converter and Boost PFC AC/DC converter as our studyobejects, the related theoretical analysis and experimental results are finished. Theachievments could provide technicla solutions for stable and reliable operation of theswitching power converter. The main work and achieved results are categorized asfollows:①In the aspect of stability analysis approach for switching power converter, animproved solution of Jacobian matrix is put forward in this paper. The obtained generalexpression could simplify the analysis of the fast scale instabilities, as also is thetheoretical basis of the subsequent follow-up work.②With peak-current mode controlled Boost PFC converter, this paper studies thecontrol effect and problems of the slope compensation(SC). With the application of theproposed Jacobian matrix solution the stable working range of the ramp parameter ofthe SC is derived, which can guide the selection of the control parameter. Theexperimental results show that the SC can effectively suppress fast scale instabilities.However, it will reduce the peak value of the steady-state inductor current and cause adistortion of the inductor current, especially near zero crossing. As a result, the SCcould worsen the power factor of the original Boost PFC converter system. This part ofthe study work illustrates the problem and reason of the traditional SC. It also illustratesa practical engineering need for the following exploration of the dynamic slopecompensation.③Regarding to the zero-crossing distortion issue of the traditional slope compensation, this paper comes up with a zero-perturbation dynamic slopecompensation scheme, which not only inherits the advantage of the original slopecompensation but also improves the disadvantage of that. With the peak-current singleloop, voltage and current double loop controlled Buck converter and peak-current modecontrolled Boost PFC converter as examples, this paper builds the zero-perturbationdynamic compensation equations repectively. The theoretical operation range of thecontrol parameter is determined using the improved Jacobian matrix solution. Theexperimental results show that the zero-perturbation dynamic slope compensationsuppresses the fast scale instabilities of the system effectively, and solves thezero-crossing distortion issue as well. Therefore, it improves the power factor of thesystem efficiently. |
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