Theoretical design of compact multi-phase interleaved buck DC-DC converter for automotive power applications

Theoretical design of a multiphase interleaved buck DC-DC converter is introduced based on corresponding requirements from automotive industry. Particularly, multiphase interleaved topology is adopted to prevent much heat generated in devices and large voltage ripple in the load. Ceramic capacitors will be used to replace electrolytic capacitors in order to meet the requirement of long life-time. Control strategy in the converter is mainly based on formulas derived for calculating duty cycle of PWM signals in both continuous mode and discontinuous mode. PID control is also included to correct the error generated from the difference in duty cycle between the ideal condition and the actual one as well as to realize fast recovery of nominal output during variation of working condition, such as variation of input voltage and variation of load. All control functions will be realized by means of a single microcontroller. The theoretical design has been tested through simulation in Simulink model, in which particular sampling frequency and control frequency of the actual microcontroller were taken into account.