Closed-loop Stability Analysis Method of llc Resonant Converter

Abstract

The present invention discloses a closed-loop stability analysis method for an LLC resonant converter based on the Floquet theory, which includes the following steps: performing linear modeling on the LLC resonant converter through extended description function modeling to obtain the system state equation group and the steady-state operating point ; By applying a disturbance at the steady-state operating point, the linear terms of the Taylor expansion of the state equations are obtained to obtain the perturbation equations of the system; the system state transfer matrix is ​​obtained by solving the Jacobian matrix of the perturbation equations, so that the system The state transfer matrix is ​​used as a stability analysis model; the stable range of the closed-loop control parameters of the LLC resonant converter is determined by analyzing the modulus length of the largest eigenvalue of the state transfer matrix. This method can accurately give the stable range of the closed-loop control parameters of the LLC resonant converter system, judge the critical stable state of the LLC resonant converter system, and the analysis process is completely based on the time domain, avoiding the solution of the high-order transfer function of the LLC resonant converter. The complexity of the stability judgment of the LLC resonant converter is effectively reduced, and the result is accurate.

Description

technical field [0001] The invention relates to the technical field of PFM (Pulse Frequency Modulation, pulse frequency modulation) type resonant converter, in particular to a closed-loop stability analysis method of an LLC resonant converter. Background technique [0002] With the development of power electronics technology, LLC resonant converters are widely used in electric vehicle charging piles, photovoltaic system DC converters, data center DC converters due to their inherent soft switching capability, high power density, low switching loss, and easy magnetic integration. power supply system. For the resonant converter, because its control method mainly adopts frequency conversion control, and the fundamental wave mainly relies on the energy transmission in the resonant network, the traditional state-space average modeling method cannot be applied. Subsequently, many modeling and stability methods of resonant converter systems appeared, such as the extended descriptio...

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Problems solved by technology

The time-domain simulation method obtains the amplitude-frequency curve and phase-frequency curve of the system through frequency sweep modeling on the simulation platform, and the physical model is not clear, and its timeliness and accuracy are limited by the simulation software

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