Research On Redundancy Technology Of IPOS Structure DC Electronic Load System

Electronic load system,a new type of power conversion system which simulates real loads by controlling the current of the tested dc power port,plays a very important role in the production and test of various kinds of power equipment.For the detection of power supply with low-voltage and high-power,the existing dc electronic load system is mostly a single device with very low reliability.Therefore,in case there is someting wrong,the load test of the power supply will be stopped.Aiming at resolving the problem of low reliability of dc electronic load system,a dc electronic load technology with modular structure and redundant function is proposed.Based on the analysis of several basic series parallel combination topology and their characteristics in modular power transformation system,combined with cold redundancy backup technology,finally determine the overall structure of inputparallel-output-series(IPOS)dc electronic load system with redundant functions.And with the help of reasonable theoretical analysis,it is proved that the reliability of the system is greatly improved by the modular redundancy technology.The redundant DC electronic load system with IPOS structure designed in this paper is composed of normal working modules and redundant electronic load modules.Every module is separated from the others,but all have the same circuit topology and working principle.The electronic load module mainly consists of two parts: load analog circuit and inverter circuit.The former part realizes the accurate simulation of various types of loads,and the latter part realizes the feedback of energy.The former part of every module tracks and controls the load current with the method of forced current sharing and PI controller,and that realizes the current balance of every module.The latter part with series output,adopts the controlling method of double closed-loop,combined with phase-shifted carrier modulation technology,to feedback energy to the system.The working status of the load analog circuit and the inverter circuit is emphatically analyzed,and the corresponding fault characteristics of each link are analyzed according to the changes of current and voltage parameters in the circuit.So that the input port current detection and single sensor multi-voltage detection are proposed for troubleshooting.And the redundant operation scheme of the system are designed to ensure the realization of the redundant function of the system and enhance the reliability of the system.Finally,the simulation software,MATLAB/SIMULINK,is used to model and simulate IPOS DC electronic load system with redundant functional structure,andthe simulation results are consistent with the theoretical results,which verifies the feasibility of the overall design scheme of the system.On the basis of that,the equivalent experimental platform is built,and the design process of hardware circuit and software function is introduced.The feasibility of redundancy design of multi-module DC electronic load system proposed in this paper is verified by experiments.