Compound Nonlinear Control Of DC/DC Converter With Constant Power Load

With the rapid development of new energy,distributed power systems have been widely used and studied.The energy conversion between the distributed power supply and the DC bus requires a DC/DC converter,so the stability of the DC/DC converter has an important impact on the performance of the entire system.The negative impedance characteristic of constant power load can easily lead to instability of the DC/DC converter system bus voltage.As the reliability requirements of the DC/DC converter become higher and higher,the traditional linear control theory is difficult to meet the demand.This paper takes Boost converter with constant power load and multi-level Boost converter with constant power load as the research objects,and proposes different nonlinear control strategies respectively.The main research contents are as follows:1.Aiming at the Boost converter with constant power load,a compound nonlinear control strategy combining fuzzy adaptive control and backstepping sliding mode control is proposed.First,the nonlinear model is transformed into a linear model by precise feedback linearization,and the fuzzy adaptive control method is added to the design of the backstepping sliding mode controller,the system gain is updated in real time according to the fuzzy adaptive control system,and the system stability is proved by the Lyapunov stability theory.Finally,the control system is verified by simulation and experiment and compared with PI control,which shows that the proposed control strategy has better dynamic performance.2.Aiming at the multi-level Boost converter with constant power load,a composite nonlinear control is proposed.A large-signal model of the system is established,and on this basis,the nonlinear model is accurately feedback linearized into a linear model,and then nonlinear disturbance observer and adaptive control method are introduced into the sliding mode controller,and the stability theory is used to prove the stability of the entire system.The control system is simulated and experimented,and the results show that compared with PI control,the proposed control strategy has better large-signal stability characteristics.