Research On Pulse Train Control Of Continuous Conduction Mode Buck Converter

With the vigorous development of power electronic technology,the requirements for switching power supplies are also increasing.Aiming at the shortcomings of pulse width control,such as slow transient response and poor robustness,pulse train(PT)control technology has emerged at the historic moment.This control technology improves the dynamic response speed and robustness of switching converter,and makes up for the shortcomings of PWM control technology.When the PT controlled switch converter works in the continuous conduction mode,there is the low frequency oscillation phenomenon,which makes the output voltage ripple larger,which can not meet the power requirements of some precision electronic equipment.In order to solve this problem,this paper proposes two solutions: multi pulse sequence control based on capacitive current and the fixed frequency dual carrier pulse train control.The main work of the paper is as follows:(1)This paper expounds the research background and significance of the paper,introduces the research status of the switch converter,and introduces the typical technologies of constant frequency control and frequency conversion control.(2)This paper introduces the theoretical analysis of PT controlled CCM buck converter and the mechanism of low frequency oscillation,analyzes the restraining effect of equivalent series resistance of output capacitor on the low frequency oscillation,classifies and summarizes the current methods to solve the problem of low frequency oscillation,and expounds its working principle,advantages and disadvantages.(3)In order to solve the problem of low frequency oscillation,a capacitor current multi pulse train control technology is proposed in this paper.Taking the Buck converter as an example,introduces its working principle and mechanism of suppressing low frequency oscillation in detail,establish a mapping model of output voltage and inductor current and analyze its dynamic behavior.Finally,thecorrectness and rationality of the capacitor current multi pulse train control method to suppress the low frequency oscillation are verified by simulation experiments and experimental prototypes.(4)In order to solve the problem of low frequency oscillation,the fixed frequency dual carrier pulse train control technology is proposed.This technology has the advantage of a wide input voltage range.Taking the Buck converter as an example,introduces the working principle of the fixed frequency dual carrier pulse train control technology and the mechanism of suppressing low frequency oscillation in detail,and analyzes the pulse control law and the ripple characteristics of the output voltage.Then establish an iterative equation of output voltage and analyze its dynamic behavior.Finally,simulation experiments and experimental prototypes are used to verify the correctness and rationality of the fixed frequency dual carrier PT control technology to suppress low frequency oscillation.