Design of Dual-Sampling and Adaptive Predictive PID Controller for Buck DC-DC Converters

摘要

In this paper, based on the combination scheme of dual-sampling and adaptive predictive PID control, a digital controller for improving the transient performance of Buck DC-DC converters is designed. Due to the inherent loop delay in analog-to-digital (A/D) conversion, the calculation process of the digital controller and digital pulse width modulator (DPWM) of conventional digitally-controlled Buck DC-DC converters limits the system bandwidth and this makes the transient response lower. The designed digital controller can reduce the delay time in analog-to-digital converter (ADC), the digital controller and DPWM of digitally-controlled Buck DC-DC converters. Adaptive predictive control is used to eliminate the delay time of ADC and the digital controller, while dual-sampling scheme is used to reduce the delay time of DPWM in this paper. These are two new control schemes, and they show better performance in improving the transient response than other existing control schemes. Both simulation and experimental results demonstrate that the designed digital controller based on dual-sampling and adaptive predictive PID control is effective in improving the transient performance of Buck DC-DC converters. During experimental verification, for a load step between 0.5 A and 1.0 A, the fastest transient recovery time and the overshoot voltage are found to be 102 ps and 120 mV, respectively. Compared with the conventional digital PID controller, the transient recovery time and the overshoot voltage of the digital controller designed in this paper are decreased by 40.0% and 27.3%, respectively.