Study On Flexible Power Distribution Strategy Of Single-phase Multi-port DC-AC Converter

In the context of the new era of energy conservation and emission reduction,research and development of clean renewable energy are gradually deepening.In recent years,renewable energy power generation technology,especially multi-port generation technology,has developed rapidly.Multi-port converter has received more and more attention and application due to its advantages such as small investment,high environmental protection,excellent cleanliness,high reliability,and flexible power generation methods.Multi-port power based on power electronics technology is of great significance for the development and utilization of new energy.This paper focuses on this topic and designs a 1.1kW single-phase multi-port DC-AC converter.The switching states of the converter and the influence of the current flowing through the DC-side ports and the duty cycle on the DC-side power are analyzed.From the perspective of theoretical analysis,the maximum power throughput of DCside ports is derived,based on which,the analytic expression and modulation strategy of arbitrary power throughput on the DC side are further derived.Finally,the topology principle analysis,DCside power throughput analysis,simulation modeling,programming,and prototype debugging are completed.The magnitude and duty cycle of the current flowing through the DC-side ports are analyzed switching cycle by cycle.The analysis of the port power is converted into the analysis of the current flowing through the ports,and further into the analysis of the duty cycle of the midpoint potential state of the bridge arm.The maximum power throughput of the DC-side ports is analyzed under unidirectional and multidirectional power flow conditions,and at the same time,analytical expressions are derived.On this basis,the flexible power distribution of DC-side ports is achieved by changing the DC-side ports energy throughput from switching cycle to cycle through combining different switching actions to change the duty cycle of the current flowing through each DC ports.So as to achieve the purpose of active and flexible control of power for the converter.The correctness of the proposed modulation strategy and the accuracy of the theoretical derivation are verified by building a Matlab/Simulink model.At the same time,a set of 1.1kW single-phase multi-port DC-AC converter experimental platform is designed and developed and the experimental results and simulation results verify the modulation strategy mentioned above under different DC voltage and power distribution coefficients.