Modeling And Simulation Of Nonideal DC-DC Converters

Modeling analysis of DC-DC switching converters is the key step to study, analyze and design switching power supplies. This dissertation is devoted to study on modeling and analyzing DC-DC switching converter. The research results are helpful to optimize behavior and improve design efficiency of switching power supplies.A circuit averaging method exemplified by Boost converter is put forward to model nonideal basic converters operating in the continuous conduction mode(CCM). Steady-state and dynamic small-signal analysis are discussed based on the derived models. Simulation analysis and experiment verification are performed. Parasitic components and current ripples existed in actual converters are included into the derived models, which are intuitive and of clear physical meaning.The circuit averaging modeling method of nonideal converters operating in the discontinuous conduction mode (DCM) is presented. A duty ratio constraint which leads to a full order model is introduced. The method is exemplified by modeling nonideal Boost converter. Based on DC circuit model and small-signal equivalent circuit model, steady-state analysis is performed, transfer functions are obtained, small-signal characteristics are studied in detail with simulation and theory analysis. Models of nonideal converters operating in CCM and DCM are combined.The modeling method of soft switching converters which is exemplified by ZVZCS full bridge converter is presented. Each state of the half switching period has been studied in detail, in which the voltage of block capacitor and current of leakage inductance of main transformer and keeping time of each state have been discussed. In term of effective duty ratio, the model of the converter is founded. Then small-signal transfer functions and step response are simulated.Finally exemplified by nonideal Boost converter operating in DCM, PID compensation networks topology and parameters are founded. Then the closed loop performance of the whole switching power supply system is simulated. The results show reasonableness of the presented modeling method which gives guidance for designing circuit.