Research On Multiphase Interleaving Buck Converters With Low Ripple

For some specific occasion,converters are required to output voltage with low ripple,high power and continuous tunableness,while the multi-phase interleaved technology has some advantages in this case.This tchnology is widely used in low voltage and high current applications,such as PC converter.The technology makes the converter output low ripple voltage with high frequency,and improve the filter network.It can be used in the laboratory power supply,high-precision DC steady power supply etc.The low ripple of this converter is achieved by interleaving the currents of each phase.It's difficult for hardware circuit produces high accurate interleaved phase angle.So the accuracy can be generated by digital controller.The output ripple and phase sharing current of multiphase converter are studied in depth,which can improve the performance of low ripple and high power converter.In this paper,six interleaved parallel Buck circuit is selected as the main power topology,and the same filter capacitor is connected among each phase to the load.According to the interleaving principle,the mathematical expressions between the two-phase converter are deduced,and the relation between the output ripple of the polyphase converter and the phase number and duty cycle is analyzed theoretically.The output filter capacitor should be redesigned,when the inductance of the capacitor is not satisfied and the voltage ripple requirement is same.So in this paper the state space averaging method is adopted as the model of multiphase converter.Based on the two phase small signal model,an internal loop regulator is designed,and the results of simulation and experiment verify the current sharing effect.The zero crossing technique is used to correct the ripple of the phase current ripple,which can significantly reduce the amplitude of the ripple in the transient and the time of recovering.By simulation and open loop experiment,the rationality of the designed parameters of converter is verified.A prototype of six interleaved parallel Buck converter is built.Closed loop experiment of multi interleaved Buck converter is carried out by using inner loop regulating current sharing method.The experiment results show that the designed converter satisfies the performance of phase sharing current and low output voltage ripple.