The Bifurcation And Its Control In Current-mode Controlled Boost Converter

Current-mode Controlled Boost Converter is a kind of voltage conversion equipment, which is widely used in various types of electrical installations. Compared with voltage-mode controlled Boost converter, Current-mode controlled Boost converter has many advantages, including quicker dynamic response, simplified compensation circuit, larger gain wideband, smaller output inductor and easier to average current, etc. Furthermore, it can't be replaced in the field of active power factor correction for the advantages of its circuit structure, and these is disputable facts. However, it also has disadvantages. As current-mode controlled Boost converter is a strongly nonlinear system, it's easier to be unstable during working due to the inappropriate choice of circuit parameters or external disturbances, which seriously affects the normal use of all kinds of electrical installations. Therefore, the instability has become a important bottleneck to the application of such system.Current-mode control is divided into the peak current control and average current control. When the peak current control is used as well as the duty circle is more than fifty percent, the system open-loop unstable, prone to harmonic oscillation, and its anti-jamming ability, especially when small inductor ripple current components, this situation is even more serious. At present, most projects adopt the method of slope compensation by superposing ramp signal over induct current to achieve the purpose of controlling the stability of the system. Currently, however, the choice of the parameter (slope m values) mainly depends on the experience and repeated trials, the system operation can not be observed vividly and objectively.This paper, based on the chaos theory and other nonlinear theories, studies the instability behavior of the Boost converter, especially makes a detailed analysis and derivation on the nonlinear phenomenon of the Current-mode controlled Boost converter. It's at present a cutting-edge research method to study the field of nonlinear circuit by using the nonlinear theory. There are many control means in view of the stability study of the Boost converter, which can be generally divided into feedback control and non-feedback control method. Non-feedback control method is widely used, as it is very useful and mature, but it also has its inherent defects, such as the low control efficiency, narrow applied face and difficult to grasp the control accuracy, etc. Although frequently used in projects, slope compensation method needs to adjust the control parameter according to the experience, which greatly increased the workload of design process and the difficulty of operation, thus limiting the application of this method. This paper will use the non-feedback control method to study and analyze the two-dimensional bifurcation of the current-mode controlled Boost converter under the action of disturbance intensity and phase disturbance, which allows us easily observe and summarize the operating rules of the current-mode controlled Boost converter, making it easier for engineering staff to choose more accurate control parameter on the basis of understanding the system operating rules, reducing the workload of design process and the difficulty of the operation. Therefore, the study of this paper is very practical in the engineering.