Dynamical Analysis of Switching Frequency Reduction-Induced Nonlinear Behavior in Bipolar SIDO Boost Converters with Peak Current Mode Control

There exists stronger multipath power flow interaction in bipolar Single-Inductor Dual-Output (SIDO) converters than in unipolar ones, which leads to more complex nonlinear dynamical behaviors. In practical applications, switching frequency reduction always appears in one-cycle controller, whereas it rarely does in Peak Current Mode (PCM) control. Surprisingly, switching frequency reduction occurs in PCM bipolar SIDO converters, which severely degrades system performance. In this paper, nonlinear behaviors induced by switching frequency reduction in a bipolar SIDO Boost converter with PCM control are thoroughly investigated. First, a unified discrete mapping model is proposed to describe the entire dynamical transition process within multiple clock cycles. Then the dynamical evolution of nonlinear behaviors induced by switching frequency reduction is studied numerically and theoretically. Two types of dynamical mechanisms of switching frequency reduction are uncovered. It is found that for Type I mechanism, border collision between Modes AII and BII gives birth to switching frequency reduction, and for Type II mechanism, the second border collision between Modes BII and BIII, inspired by period-doubling bifurcation, gives birth to switching frequency reduction. Besides, relative eigenvalue sensitivity and correlation factor are utilized to evaluate the relationship among parameters, eigenvalues and state variables. To provide more information for design-oriented optimization, stability regions are obtained to guide system optimal design. Finally, these PSpice circuit experiment results are used to verify the theoretical results.