Title :
Fast-Transient Integrated Digital DC-DC Converter With Predictive and Feedforward Control
Author :
Huey Chian Foong ; Yuanjin Zheng ; Yen Kheng Tan ; Meng Tong Tan
Author_Institution :
Sch. of Electr. & Electron. Eng., Nanyang Technol. Univ., Singapore, Singapore
fDate :
7/1/2012 12:00:00 AM
Abstract :
This paper introduces a dual-mode digital dc-dc converter combining the predictive and feedforward control with the conventional PID controller to achieve fast transient response and low overshoot. An additional predictive or jerk component is added to the conventional PID controller to speed up the transient response and reduce the settling time by approximately 50%. This predictive term is based on the second derivative of the error signal and introduces zero to the loop response which leads to increased bandwidth and improved phase margin. In addition, a feedforward control is also employed to further improve the transient by evaluating the change in the inductor current during the on and off time of the power transistors. Theoretical analysis and simulations were carried out to analyze the proposed design and algorithm. The proposed design is verified on silicon with a prototype of a digital dc-dc converter fabricated in CMOS 0.18 μ m process. The digital dc-dc converter achieved a settling time of 4 μs and an overshoot of 15 mV for a step-load transient of 450 mA, which are improved significantly as compared to the prior arts.
Keywords :
CMOS integrated circuits; DC-DC power convertors; control system synthesis; feedforward; power transistors; predictive control; three-term control; CMOS process; conventional PID controller; current 450 mA; dual-mode digital dc-dc converter; error signal; fast transient response; fast-transient integrated digital dc-dc converter; feedforward control; inductor current; jerk component; loop response; low overshoot; phase margin; power transistors; predictive component; predictive control; second derivative; size 0.18 mum; step-load transient; time 4 mus; voltage 15 mV; Clocks; Computer architecture; Delay; Feedforward neural networks; Microprocessors; Pulse width modulation; Transient analysis; Digital dc-dc converter; fast-transient; feedforward control; predictive control;
Journal_Title :
Circuits and Systems I: Regular Papers, IEEE Transactions on
DOI :
10.1109/TCSI.2011.2177012