Aiming at the problem that the nonlinear time-varying model of the existing Buck converter is complicated

which is difficult to design the controller

the nonlinear model is transformed into the U model by using the time-varying polynomial

which simplifies the complexity of the nonlinear model controller design. On the basis of traditional proportional-integral-differential（PID） controller

the fuzzy PID controller based on U model is designed by using fuzzy algorithm and U model structure. The controller output is solved by Newton-Raphson iterative algorithm. The new controller maintains the general characteristics of the PID controller

improves the control precision

dynamic performance and adaptive ability to non-linear disturbance of the Buck converter

and provides a new way to solve the design of the Buck converter controller.