The Dc-dc Switching Power Supply Charge Control Mode Applied Research

In recent years, DC-DC converters have been widely used in electrical drive anda lot of else applications. Ordinarily, a DC-DC converter contains a power stage and acontroller. Different control strategies could been used basing on the power stagetopology and the application occasion. DC-DC converters have two basic controlmodes, the voltage control mode and the current control mode. The charge control isa kind of current control. It is an nonlinear control method and has the advantage offast response. The charge control could been used not only for linear loads, but alsofor nonlinear loads.The charge control for DC-DC converters was studied in this paper and theimportant was the charge control for Boost converters with a permanent power loadand the digital realization of the charge control method.Firstly, the basic principle of the charge control for DC-DC converters wasdescribed. The models of the ideal Boost converter and the ideal Buck converter wereintroduced. The dynamic small-signal analysis for the charge controlled convertersystem was done basing on the model of DC-DC converters.Secondly, a quantitative permanent power load model was presented and theBoost converter model with a permanent power load was gotten. The model of thecharge controlled Boost converter system with a permanent power load wasintroduced. Proportional-Integral control and charge control method were analyzedusing Matlab-Simulink. The analysis result indicates that the Proportional-Integralcontrolled Boost converter with a permanent power load could be unstable on someoccasions, while the charge controlled Boost converter with a permanent power loadis stable and has fine dynamic characteristics.The discrete integral was done. The expression transforming output voltagesetting to charge setting was established and a charge controlled multi-loop systemwas gotten. A DSP control program directly corresponding to the discrete integral wasdesigned. The program will arouse the duty jump of adjacent switching periods,which has potential influence to the stability of the system. The improved DSPcontrol program was designed to eliminate the duty jump and improve the controlprecision.A charge control resistance load Boost converter experiment system and a chargecontrol permanent power load Boost converter experiment system were founded. Theresults of the experiments confirmed that the charge control method is applicable forresistance load Boost converter and permanent power load Boost converter.