Digital Charge Balance Controller to Improve the Loading/Unloading Transient Response of Buck Converters

Abstract

A linear/nonlinear digital controller is presented that allows a Buck converter to recover from a load transient event with near-optimal voltage deviation and recovery time. A novel digital double accumulator calculation block is used to calculate the appropriate pulse width modulation switching time instants. The proposed controller possesses many advantages not demonstrated by a single controller in the previous literature. For example, unlike many previously proposed time-optimal digital controllers, the proposed controller provides an excellent transient response as it is capable of reacting asynchronously to a load transient event. In addition, it is demonstrated that the proposed controller can operate without requiring information pertaining to the Buck converter's output inductor. Furthermore, the proposed controller can be extended to applications that require load-line regulation. Lastly, unlike all previous digital time-optimal controllers, the proposed controller does not require digital multiplier or divider blocks nor does it require 2-D lookup tables. Thus, the controller can be implemented through the use of low-cost field programmable gate arrays or complex programmable logic devices.