Research On Load Transient Performance Improvement Of Multiphase Interleaved Parallel DC-DC Converter

With the continuous development and wide application of micro-processing and communication equipment,the DC/DC converter as a power supply requires low voltage,high current,fast load transient performance and low output voltage ripple.Multiphase interleaved Buck converter is widely used due to its own topological structure advantages.In this paper,the Multiphase interleaved Buck converter is taken as the research object,and on the basis of ensuring the good steady-state current sharing characteristics of the converter,it explores a solution to further improve the load transient performance.Therefore,the minimum time control and topology dynamic adjustment are integrated to explore the minimum time load transient regulation scheme.The main research work completed in this paper is as follows:Firstly,from the control strategy level,the idea of minimum time control is introduced into the Multiphase interleaved Buck converter.The existing traditional average current control strategy works in the same set of control parameters in both dynamic and steady state,so it is difficult to achieve optimal load transient performance.For this reason,the idea of minimum time control is introduced.In steady state,the average current sharing control is used to ensure good steady-state current sharing performance;in transient state,the transient switching sequence is calculated based on the charge balance theory to realize the minimum time regulation trajectory.The simulation and experimental results verify the applicability of the proposed minimum time control strategy to the Multiphase interleaved Buck converter and the effectiveness of improving the load transient performance.Then,from the aspect of optimizing the circuit topology,there are few researches on improving the load transient performance of the Multiphase interleaved parallel Buck converter,based on the minimum time control strategy.For this reason,in view of the unsatisfactory unloading transient of low-voltage and high-current converters,a two-phase interleaved Buck converter topology based on a series equivalent voltage source is proposed.The parallel auxiliary bridge arm structure is introduced to realize the voltage sources in reverse series connection,thereby increasing the voltage across the inductance during the load transient,and increasing the slope of inductance current during unloading transient.The transient operation mode of the proposed two-phase interleaved parallel Buck converter is analyzed.According to the theory of charge balance,the transient switching sequence of the proposed scheme is deduced during unloading transient,and the optimal effect of the unloading trajectory is achieved at the same time.Simulation and experiment results prove that the proposed auxiliary bridge arm scheme can further improve the load transient performance of multi-phase interleaved parallel Buck converter.Finally,from the aspect of optimizing the circuit topology,the phase filter inductance parameters of the Multi-phase interleaved parallel Buck converter are studied,and the load transient performance improvement scheme of the coupled inductance structure is proposed.According to the specific working mode of the proposed scheme,the working principle of the coupled inductor structure is analyzed.By further deriving the steady-state equivalent inductance and transient equivalent inductance of the coupled inductor in reverse connection mode,the influence of the proposed scheme on the steady-state performance and load transient performance of the converter is analyzed.Based on the results of mathematical calculation,the experimental circuit of the proposed scheme is designed reasonably.According to the principle of charge balance,the minimum time control algorithm of the proposed scheme is calculated.It is verified by simulation and experiment that the proposed coupled inductance scheme can further optimize and improve the load transient performance of the multi-phase interleaved parallel Buck converter while ensuring steady-state performance.