Analysis Of Dynamic Characteristics Of Bidirectional DC-DC Converter With Constant Power Load

The bidirectional DC-DC converter realizes the bidirectional flow of energy and effectively controls the charge and discharge of the battery,so it is widely used in micro-power grid,new energy vehicle,aviation ship,building power system,submarine power system and other fields.Due to the negative incremental impedance characteristics of constant power load and the nonlinear characteristics of switch,the system will produce abundant nonlinear phenomena such as bifurcation and chaos in the operation process,which will cause the system to produce noise and the system to crash suddenly in the actual work.Therefore,it is of great significance to analyze the nonlinear dynamic characteristics of bidirectional DC-DC converter with constant power load.This paper takes bidirectional DC-DC converter with constant power load as the research object,and uses Filippov method combined with Floquet theory to analyze the dynamic characteristic of the system.The research work carried out in this paper has the following two points:(1)For the bidirectional DC-DC converter with constant power load controlled by peak current,the charging and power supply models of the system in continuous conduction mode are established by using the state space method,and the nonlinear terms of constant power load are linearized by the Taylor series expansion method.In addition,Filipppov method is used to calculate the single value matrix of system power supply and charging modes,and Floquet theory is used to explore the stability of the system when the reference current and power supply voltage change.Finally,the correctness of Filipppov’s method and Floquet’s theoretical analysis are verified by simulation and experimental results.(2)Aiming at the state feedback control of a bidirectional DC-DC converter with a constant power load,the state space method is used to establish a continuous conduction state feedback control model of the system in the power supply mode,and based on the Filipppov method,the single-value matrix of the system power supply mode is obtained.The Floquet theory is used to explore the system’s dynamic characteristic under different state feedback control parameters and input voltage changes.It is also compared with the peak current feedback.Finally,different control parameters are selected through Matlab and experiments for verification.Finally,the correctness of Filipppov’s method and Floquet’s theoretical analysis system are verified by simulation and experiment.