A stability improvement method for LLC resonant converter with additional resonant current peak proportion control

LLC resonant converter is widely used in DC-DC conversion of switching power supply with its inherent soft switching and low loss performance, and its stability is particularly important. Recently, some scholars applied the stability method based on Floquet theory in the time-domain to the stability analysis of LLC resonant converter. The stability margin of the original control maybe insufficient when LLC resonant converter work under different operating conditions. Therefore, it is necessary to improve the stability margin of LLC resonant converter system. In this paper, on the basis of the time-domain Jacobian matrix model of LLC system according to the Floquet theory, combining with eigenvalue sensitivity analysis and matrix elementary transformation, the stability improvement method of additional resonant current peak proportion control is proposed. Secondly, the stable range of the newly added control parameter is analyzed based on Floquet stability criterion. Finally, theoretical analysis and PSIM simulation verify the effectiveness of the proposed additional control method and improve the stability margin of the control parameter of original system.

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