Mathematical Model And Simulation Of Voltage Mode Based On Buck Converter

With the development of power electronics, switching converter with full controlled power electronic devices as the core has been widely used in household appliances, computers and industrial control field. Because of full controlled power electronic devices working in switching mode, the conversion efficiency is very high, in order to gradually replace the traditional linear power supply. Switching converter has been in high frequency, high power density, low voltage and high current direction.This paper studies the composition and working principle of the traditional linear power supply, linear power simulation model is established, analysis of the impact of parameters on the voltage ripple, theory and simulation results show that the closed-loop voltage gain is of great significance for the ripple voltage, increasing the closed-loop voltage magnification can reduce the ripple voltage. Linear power adjustment tube in amplification, switch on both ends of the pressure to maintain output voltage stability, which leads to the low efficiency of linear power supply, heating, need the radiator, the size and weight of the large. Based on the study of the linear power supply the Buck converter as the main object of study, analysis of the composition and working principle of Buck converter, a Buck converter simulation model, the simulation waveform of Buck converter with input and output voltage and inductor current and capacitor current and the diode, verify the correctness of theoretical analysis. The mathematical model of Buck converter is built by using the state space averaging method, the voltage negative feedback dynamic structure to form a closed loop system, research the system open loop logarithm amplitude frequency characteristic and phase frequency characteristic, control to output transfer function, input-output transfer function and open loop output impedance. The stability of the system is analyzed and its dynamic performance,simulation results verify the correctness of the theory.Finally, based on the 28 V input voltage 12V/4A output for example, under the steady state according to the requirements of the switching power supply performance index parameters calculation, design of inductance and capacitance, the power stage transfer function analysis, feedback system transfer function and the open-loop transfer function of the system is to meet the design target, establish the simulation model of closed loop control system. The simulation results meet the design requirements.