A Novel Modeling Method of Nonideal Buck-Boost Converter in DCM

A new modeling method of Buck-Boost converter operating in discontinuous conduction mode (DCM) is presented. The method is based on the principle of energy conservation and equivalent circuit modeling method. In the modeling, the parasitic components of the Buck-Boost converter and the MOSFET delay are considered. Large signal averaged, dc and small signal circuit models of the Buck-Boost converter are derived. The open loop transfer functions are educed. Based on it, the instruction of the parameter optimization and control loop design can be given. The simulation results show that: (1) The parasitic components have influence on the transfer functions, time domain and frequency domain characteristics. (2) The MOSFET delay has effect on high-frequency performance and loop stability. In addition, the method is characteristics of high precision and small computing quantity.