Digital Control of Hard Switched Converters by Phase Modulated Pulse Width Modulation PMPWM

Abstract:
The small signal models of hard switched buck and boost converters are depending on their operating point and operation mode such as Discontinuous Conduction Mode (DCM), Continuous Conduction Mode (CCM) as well as different variants of PWM implementations. This forces the control loop to be adaptive or to compromise on performance versus stability margin. By expanding the power switch control from PWM to the Phase Modulated PWM scheme, as presented in this paper, it is possible to set up switching wave forms showing a constant linear small and large signal behavior to the control loop. This unleashes maximum control loop performance and stability while saving output capacitance as well as the converter’s physical voltage and current safety margin.