Research On Input-Parallel Output-Series DC/DC Converter Applied In High Voltage Collection For PV Generation

With the increasingly serious environmental pollution.It's quiet important for people to seek a clean and non-pollution green energy.So the photovoltaic power generation technology has brought people's attention.At present,China has built a number of photovoltaic power stationes in Qinghai province,Gansu province and other western regions.However,the problem of PV power generation is that the power generation capacity of PV panels can be affected by various uncertain factors such as sunshine intensity and sunshine duration.The photovoltaic array boards can not work at the maximum power point all the time,which makes each photovoltaic array board is an unstable power supply,resulting in a very serious phenomenon of photovoltaic abandonment.The power grid output channel capacity can not match the development of photovoltaic power stations,which directly leads to the low efficiency of photovoltaic power plants.Input Parallel Output Series Converters are suitable for high power applications where the input side voltage is low and the output voltage is relatively high.reducing the requirements for transformers in DC/DC converters.Which means the input parallel output series DC/DC converter can be used in photovoltaic power generation technology.This paper introduces the input parallel output series DC/DC combinational converter which is used in high voltage photovoltaic DC flooding.In this paper,the DC/DC converter uses dual active bridge(DAB)bidirectional DC/DC converter as the submodule.This paper introduces the topology of dual active bridge DC/DC converter and deduces the operation principle of dual active bridge DC/DC converter.The circuit parameters of the dual active bridge are designed based on the results of the derivation.Then the paper introduces the topology of input parallel output series converter,analyzes and discusses various factors that affect the input voltage and output voltage sharing.In order to make sure that the photovoltaic array boards can always work at the maximum power point,this paper designes the PI controller parameters to make sure that the output voltage sharing can not be affected by the parameter difference.After the theoretical analysis is finished,the open-loop and closed-loop simulation models of the input parallel output series DC/DC converter are established using Matlab / Simulink simulation software.The theoretical derivation and verification of the dual-active-bridge DC/DC converter are verified according to the simulation results.The simulation results verify the rationality of dual active bridge DC/DC converter,and the IGBT can achieve soft switching.It is verified that the input voltage can be stabilized under the control of the PI controller when the input side voltage fluctuates.It is verified that the output voltage of the combined converter can be divided equally when the sub-module parameters fluctuate.Finally,hardware of the phased control board and the sub-module board has been designed.The input parallel output series DC/DC converter consists two-dual active bridge submodule.Based on the Verilog language,the open loop experiment and closed loop experiments have been done to prove the proposed method.The input voltage and output voltage sharing can be achieved successfully.