Buck-type converter cascade system stability analysis method based on gyrator model

Abstract

The invention discloses a Buck type converter cascade system stability analysis method based on a gyrator model, and belongs to the technical field of power electronics and control. The method comprises the following steps: 1, selecting an inductive current and an output voltage as state variables, establishing a large signal model of the converter in a continuous conduction mode, and obtaining a differential equation about the inductive current and the output voltage; 2, deriving a state-space equation according to the differential equation in combination with PI control, voltage feedback and a gyrator model, and performing derivation; 3, popularizing the matrix to a converter cascade system to derive a state space matrix of the cascade system, and deriving; and 4, observing the stability of the cascade system through the complex plane characteristic value trajectory diagram and the characteristic value discrimination theorem, and obtaining the influence of the change of each parameter on the stability. On the basis of a traditional large-signal model, a gyrator model and a complex plane characteristic value trajectory diagram are adopted, a transfer function does not need to be calculated, a Baud diagram does not need to be drawn, and the stability change when a certain parameter changes can be directly observed.

Description

technical field [0001] The invention belongs to the technical field of power electronics and its control, and more particularly relates to a method for analyzing the stability of a cascaded system of buck converters based on a gyrator model. Background technique [0002] In the DC distributed power system, the cascade structure is one of the basic connection forms, and the stability is the most important operating index of the DC-DC converter cascade system. May become unstable due to interaction with each other. Most of the traditional stability analysis and improvement methods are proposed in the frequency domain based on the impedance model of the system. However, the impedance formula proposed based on engineering experience is relatively conservative and the impedance calculation is complex, so it is difficult to generalize to a cascaded system with more than three stages, and is mostly used in a two-stage cascaded system. Most of the current stability improvement met...

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Problems solved by technology

[0020] Aiming at the difficult calculation and complex analysis of the existing DC-DC converter cascaded system impedance, and the situation that it cannot be applied to multi-level cascaded systems, the present invention proposes a buck-type converter cascaded system stability based on the gyrator model Analysis method; on the basis of the traditional large signal model, the invention adopts a gyrator model that can convert output voltage and input current, output current and input voltage to each other, and calculates the gyratory conductance from this, combined with PI control and Voltage feedback control constructs the state space equation, and obtains the Jacobian matrix after derivation

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