Enhanced control strategy for parallel DC-DC converters based on extended state observer
To further improve the dynamic performance of parallel DC-DC converters under various inner and outer disturbances,an enhanced control strategy based on dual-loop extended state observer(ESO)was proposed.In this strategy,the proportional regulators were combined with ESOs,and then applied to common outer voltage loop and each inner current loop respectively.In no need of extra sensors,the dy-namic current sharing among power units was realized and the ability of input voltage disturbance rejection was also strengthened.Firstly,the expressions of ESO-based inner-loop current control were deduced based on the state equations of parallel converter.After that,according to the poles distribution of closed current loop,the reason why the ESO-based current loop performed better than the proportional-integral-based current loop in terms of input-voltage disturbance rejection was analyzed in theory.Besides,with the help of bode plots,the theoretical evidence that the ESO-based current loop had stronger robustness against mismatched inductances and could effectively remove the dynamic current deviations was given.Finally,a three-phase buck converter was used to conduct the comparative validations of different schemes.The experimental results verify effectiveness and advancement of the proposed strategy in terms of dynamic performance improvement.
parallel DC-DC converterextended state observerdual-loop controlparameter robustnessdisturbance rejectiondynamic current sharing
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