Digital Current-Mode Controller Using Delta Operator and Advance Sampling Predictive Control for High-Frequency DC–DC Switching Converters

Abstract

High-frequency digitally controlled dc–dc switching converters have many advantages, such as very fast transient response and high-power density. However, the studies of control strategies and algorithms specifically for high-frequency digitally controlled dc–dc converters are seldom reported. In this study, we propose a novel digital current-mode controller consisting of both output voltage and inductor current compensators for high-frequency dc–dc switching converters. The voltage compensator is designed based on the delta operator instead of the shift operator, which could improve the control accuracy and reduce hardware costs. Furthermore, the current compensator is designed using an advanced sampling predictive (ASP) control strategy to reduce the requirement of hardware processing speed, and in turn the hardware cost, and to eliminate the influences of noise caused by power switch commutations. Finally, a buck dc–dc switching converter with a switching frequency of 2 MHz is designed and implemented using the proposed digital current-mode controller on a field-programmable gate array (FPGA) platform. Our test results indicate that better control accuracy and lower hardware costs can be realized using the delta operator instead of using the shift operator. In addition, compared with the single digital voltage compensator, the proposed digital current-mode controller has better transient response performances. The control strategy and algorithm proposed in this study are especially effective for digitally controlled high-frequency dc–dc switching converters.