Cascade DC-DC converter stability analysis method based on describing function method

Abstract

The invention discloses a cascade DC-DC converter stability analysis method based on a describing function method. The cascade DC-DC converter stability analysis method includes the following steps: performing linear modeling on a linear part in a single-stage DC-DC converter in a cascade system through a small signal modeling method to obtain a first linear transfer function; performing nonlinear modeling on a switch link of the DC-DC converter through a describing function method to obtain a describing function; performing equivalent processing on a source converter through a converter equivalent method to obtain a second linear transfer function, and determining the stability range of a two-stage cascade DC-DC converter according to a relation between the second linear transfer function and the describing function; and performing equivalent processing on a load converter through the converter equivalent method to obtain a third linear transfer function, and determining the stability range of the two-stage cascade DC-DC converter according to a relation between the third linear transfer function and the describing function. The method of the invention can accurately determine the critical stable state of a converter system and effectively improve the accuracy of judgment results.

Description

technical field [0001] The present invention relates to the technical field of cascaded PWM (Pulse Width Modulation, pulse width modulation) type DC-DC converters, in particular to a cascaded DC-DC converter stability analysis method based on a description function method. Background technique [0002] With the development of power electronics technology, DC-DC converters are widely used in systems such as computers, electric vehicles, photovoltaic power generation, and aerospace. For a single converter module, although its individual operation is stable, it cannot guarantee the stability of the entire system after integration. Later, many methods for judging system stability appeared, such as Middlebrook impedance criterion, state space averaging method, etc. . However, these methods process the system based on linearization and averaging methods, resulting in certain errors in the judgment results. [0003] In the related art, a solution to the problem of instability in ...

AI Technical Summary

Problems solved by technology

The stability criterion of the descriptive function method was first applied to the DC converter to analyze the stability of a single boost converter, but it has not been applied in the DC-DC converter cascaded system because the PI regulated There are two nonlinear links in the DC-DC converter cascaded system, so they need to be dealt with and need to be solved

Images