Adaptive tuning of digitally controlled switched mode power supplies based on desired phase margin

This paper presents an online adaptive tuning technique for digitally controlled switched-mode power supplies (SMPS). The approach is based on continuous monitoring of the system crossover frequency and phase margin, followed by a multi-input multi-output (MIMO) control loop that continuously and concurrently tunes the compensator parameters to meet crossover frequency and phase margin targets. Small-signal models are derived and the MIMO control loop is designed to achieve stability and performance over a wide range of operating conditions. Using modest hardware resources, the proposed approach enables adaptive tuning during normal closed-loop SMPS operation. Experimental results demonstrating system functionality are presented for a synchronous buck SMPS.