Research On Input Voltage Feedforward Control Of Buck Converter With State Observer

In recent years,with the rapid development of strong smart grid and UHV technology in China,power system automation control devices have been widely used.The stable output of DC voltage in relay protection control device is very important to ensure the safe and stable operation of power system.At present,buck circuit is widely used in substation automation DC control system.For single-phase buck converter,because the front stage is a single-phase rectifier topology,the inherent secondary pulsation in its power results in the DC side ripple with twice the grid frequency fluctuation.Therefore,we design and study buck converter(without LC filter)and find a new strategy to suppress the secondary ripple voltage.Firstly,this paper investigates the research status at home and abroad,analyzes the working principle of single-phase buck converter,and through the analysis of the influence path of the secondary pulse voltage in the later stage buck converter,it is concluded that the secondary ripple can affect the output voltage of the converter through the control loop and the front loop of the equipment hardware,and its influence will eventually flow into the output terminal of the converter.At the same time,through the simulation in MATLAB,the correctness of the theoretical analysis is verified.Secondly,aiming at the deficiency of voltage output quality of front-end single-phase rectifier and back-stage buck converter,a controller is designed to suppress the secondary ripple voltage,which increases the stability of DC power supply of power grid protection device and control device.Another feed-forward channel of output interference voltage is added in this paper.On this basis,the input voltage feedforward method of buck converter is designed to further eliminate the influence of secondary ripple on output voltage.Finally,through MATLAB simulation,the proposed method is compared with the traditional control methods such as proportional integral and input voltage feedforward,and the effect of the two methods on the suppression of secondary ripple is compared.The results show that the proposed method is feasible and effective in suppressing the influence of secondary ripple on the converter.