Passivity-Based Control Of Buck-Boost Converters

With the continuous development and advancement of technology and society,people are increasingly demanding the quality of power output from power electronic devices.In particular,today the country calls for the development of new energy sources,which can convert sustainable energy sources such as wind energy and solar energy into electricity for people to use.However,such energy sources have various interference problems or wide-ranging fluctuations.In order to obtain stable and high-quality electric energy,the control method of switching power supply has become a research hotspot of various scholars in recent years.Compared with the linear control method,the nonlinear control method has better robustness and stability.The passivity-based control method is widely applied because it is simple in structure,easy to implement,strong in robustness,high in stability,good in dynamic performance.The Buck-Boost DC-DC converter is used as the research object to study the passivity-based control method.The passivity-based control methods originate from network theory and other branches of physics,and designed the controller mainly from the perspective of energy.Based on the definition of passive and dissipative,combined with its correlation with stability,the controller is designed based on the port-controlled dissipative Hamiltonian system.Firstly,the basic working principle of Buck-Boost converter is analyzed in detail by the equivalent circuit method.According to whether the inductor current is continuous,the two working modes are derived.Based on this,the large signal model,small signal model and state space average model of the Buck-Boost converter in the continuous mode of inductor current are established.In order to get better performance of Buck-Boost converter system,the mathematical model of Bcuk-Boost converter is first transformed into PCHD model form.By adopting interconnection and damping assignment passivity-based control method,The passivity-based controller based on PCHD model of Buck-Boost converter is designed and stability of system is verified.Then the effectiveness of the control method is verified by Matlab/Simulink simulation software.Aiming at the influence of the injection damping coefficient on the system in the passivity-based controller based on PCHD model,the control effects under different values are analyzed.A novel second-order tracking differentiator is designed to make the injection damping coefficient change smoothly and continuously,so that a larger injection damping coefficient can be given to accelerate the convergence speed when the system starts,and a smaller injection damping coefficient is given to reduce the steady-state error of the system when the system is close to the steady state.So the variable damping passivity-based controller based on PCHD model is obtained,which further improves the dynamic performance and static performance of the Buck-Boost converter.Finally,according to the design control scheme,the experimental platform of the system is built with DSP as the control microprocessor.In the CCS integrated development environment,the software is programmed,debugged and downloaded according to the control algorithm studied.The superiority of variable damping passivity-based control is verified by comparison with the constant damping passivity-based control.