Compensator design for digital controlled switched-mode power supplies

In switching power supply system, compensator in feedback loop plays an indispensable role in system stability and performance improvement. While digital controlled power converter, due to the quantization effect, brings new challenge to compensator design. This paper presents a complete design process for a digital compensator, which begins from designing an analog compensator, then going through a conversion from s-domain to z-domain to obtain discrete time equivalent transfer function. As a key point, constrain brought by limit cycle oscillation, error introduced by approximate conversion and comparison of different structures of compensator are all under consideration. All conclusions are illustrated by simulation results based on simulink model.