Nonlinear PID in Digital Controlled Buck Converters

Digital controller provides capability to implement flexible control algorithm. The nonlinear PID function with power coefficients is proposed in this paper, which can be easily applied to digital control of switching dc-dc converters. The buck converter with nonlinear PID compensation is studied and compared with linear PID compensation. The start-up transient and transient response under different load variations are investigated by simulation. The experiment system is also set up on FPGA platform to verify the analysis and simulation results. By comparison, nonlinear compensated converter has much better performance than the linear compensated one.