| Ripple-current control is widely used in a variety of switching power converters because of its excellent characteristics,including a fast transient response,a simple structure and low cost,and so on.However,there are still some defects.In traditional double-loop structure of ripple-current control,its dynamic performance of system would limit by bandwidth size of outer-loop compensator.Otherwise,the control is limited in the use of current-controlled precisely occasions due to poor current-controlled accuracy.In addition,sub-harmonic oscillation and other fast variable behaviors prone to happen in ripple-current control.To this end,a current-ripple-compensation control is researched in this paper.The main idea is to retain all the advantages of ripple current control and remedy its shortcomings,and furtuer combine the advantages of high current control accuracy in average current control mode.Thereby,ripple-compensation average current control is prosed in this paper.Furthermore,the specific applications of prosed control in a DC-DC converter and an AC-DC converter are studied to verify the effectiveness of prosed control.The main work and achieved results are categorized as follows:First of all,a ripple-compensation average current control is proposed to solve the shortcomings of traditional ripple current control and further improve its work performance of switching power converters.The current reference of current-inner-loop is given by a new way.Thereby the integral link of outer-loop compensator can be canceled to get a faster transient response.At the same time,feedforward control must be introduced to ensure no error output in steady-state.Combining with high current precision of average current control,a ripple compensation control is introduced in prosed control to achieve average current control in current-inner-loop.At the same time,the introducing of ripple-compensation signal could also suppress sub-harmonic oscillation effectively and enhance its stablility of the system.This part proposes the ripple-compensation average current control strategy,which provides a feasibility control scheme to enhance their performance of switching power converters furtherly.Secondly,the prosed control is applied in specific experimental circuits to verify its validity of prosed control.In DC-DC converter,Buck converter is used as the main research object.The specific control structure is given directly and simplified further.And then the corresponding control equations are constructed.Furthermore,the optimization of control parameters is analyzed on the basis of small signal model.In AC-DC converter,Boost PFC converter is used as the main research object.The reference current of inner-loop is reconstructed based on law of power conservation.The selection of control parameters is based on small signal model and a plenty of simulation experiments.The final simulation and experimental results verify the validity of proposed control and the correctness of theoretical analysis.This part of research content provides theoretical guidance for the prosed control used in practical engineering occasions. |
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