Digital power controller with sensorless DCM operation

This paper presents a sensorless digital controller method that is able to detect the switching power converter´s inductor current zero-crossing point and operate in discontinuous conduction mode without the need for sensing the inductor current. The presented controller is based on minimizing the duty cycle of the upper side switch of the DC-DC buck power converter while perturbing the lower side switch turn off time. Since the inductor current sensing and its zero-crossing point detection are eliminated, the associated noise and ringing issues are eliminated and there is no need for high speed sensing and sampling of the inductor current, which is of advantage especially at high switching frequencies and when digital controller is used. An algorithm to realize this concept is discussed and experimental results are presented.