A technique for duty-cycle prediction using the next change-in current and error

A duty-cycle prediction technique for current mode digital control DC-DC converter is presented. An equation for a duty-cycle prediction is derived using the correlation between the estimated change-in instantaneous current and the present sampling error. A small-signal model is used as the control design model for the voltage-loop control. The voltage-loop control provides the controlled reference for the current-loop control. Unlike the previous prediction technique, the instantaneous inductor current is not assumed to reach the reference value within one or two sampling periods. Also, the previous value is not included in this prediction technique, but the estimated future value. With this technique, high frequency switching noise appears on the inductor current waveform can be reduced significantly. Both the simulation and the experimental results are presented to evaluate the idea. This technique can be applied for other DC-DC converters.