| Due to new energy power generation system’s output limits of low-voltage and high-current,it is necessary to adopt a suitable boost topology to raise the output voltage to realize further power conversion in the subsequent stage.In this paper,innovative high step-up DC/DC converters are put forward and gradually optimized when combined with interleaved structure,active-network topology and switched-inductor/capacitor-diode units,whose effectiveness is verified by simulation/experimental results.First of all,an active-network DC/DC Boost converter with capacitor-diode units is proposed,in which capacitor-diode units are added across the inductors on the input side of the active-network structure.On the one hand,working modes are clarified in detail from ideal/non-ideal states.On the other hand,the steady-state performance of the proposed topology is analyzed and will be compared with commonly-used boost converters.It is obvious that although the proposed converter features small inductor current and low voltage/current stresses on power devices,its voltage gain is limited.In addition,due to the defect of limited voltage gain in the first topology,an interleaved boost converter with switched-inductor/CD units is put forward by substituting the active-network converter with interleaved boost converter,replacing the inductors on the input side with switched-inductor units and adding a CD(capacitor-diode)unit to the output side.Although the introduced converter indicates the advantage of high step-up voltage gain when retaining the characteristics of small inductor current and low voltage/current stresses on power devices,the efficiency of the entire system is low.Then,due to the disadvantage of low efficiency in the second topology,an interleaved high step-up DC/DC converter with a charge pump is proposed by replacing switched-inductor units with a charge pump structure.Compared with the other two topologies,although its voltage gain is not as high as the second converter,it can satisfy the requirements of pre-stage power conversion of new energy power generation system,whose voltage stresses of the switching tube/output diode are the lowest and theoretical efficiency can reach above 93.4%.On this basis,its closed-loop controller design is carried out according to state-space averaging principle,it is obvious that the output voltage/current can be restored to a given value within 0.018 s with a step change in resistive load variation.Last but not least,hardware circuit design of the third topology is clarified in detail and a150 W experimental prototype of power conversion is established,whose results indicate that experimental values are consistent with theoretical calculations and the introduced topology has higher step-up voltage gain/better antiload disturbance performance in the pre-stage power conversion of fuel cell.When the input voltage is 16 V,the efficiency of the entire system at rated power can reach about 94.2%. |
