| The large-scale promotion of energy saving technology and the increasing demand of power supply device,driving the rapid growth of the market for electronic load.The energy-feedback electronic load has the advantages of low energy consumption and flexible load matching,therefore is becoming the mainstream product among the loads.But the promotion of the energy-feedback electronic load is restricted by the high cost of equipment and the low-quality of feedback power.Therefore,the economical and efficient solution with high-quality of feedback power and fast dynamic response becomes the research hotspots of energy-feedback DC electronic load.Taking energy-feedback DC electronic load as the research object,the paper analyzes the technical status and development trend of energy-feedback electronic load,focusing on the efficient hardware topology and control strategy of high-precision load simulation as well as the feedback of high-quality power.Finally,a practical experimental platform is set up to test the property of energy-feedback DC electronic load prototypes.The main content of the thesis is shown as follows:(1)The hardware system for energy feedback electronic load is analyzed and designed.Taking the cost and the efficiency into consideration,the topology of “Boost and Full-Bridge” and the chip of TMS320F2808 are adopted.The former is chosen for the power transformation circuit and the latter is used in the control core of the high accuracy sampling circuit.The experimental results show that the maximum reference error of the signal sampling is only 2.032%,and the overall efficiency is as high as 96.03% when the input power is 2000 W.(2)A load simulation control strategy based on fuzzy control is proposed.It is available to adopt a kind of control program using “digital outer loop and analog inner loop”.The introduction of fuzzy control rule into the control system could optimize the response speed and steady-state accuracy of the load simulation and decrease the input current overshoot.When it works in 15 A constant current mode based on fuzzy control,the simulation shows that the adjustment time is reduced by 75.2%,the steady-state error is reduced by 60%,and the overshoot decreased from 28.3% to 7.47%.(3)An improved deadbeat control strategy based on “interpolation prediction and on-line inductance identification” is proposed.Aiming at the delay problem of deadbeat control,an improved interpolation prediction algorithm is proposed to compensate it.Besides,to correct the inductance deviation,an on-line inductance identification algorithm based on double frequency sampling is also adopted,which can effectively improve the control accuracy and the quality of grid-connected power.It is indicated that an output constant current of 10 A situation is available with the deadbeat control relative error of only 0.2%,the grid-connected power factor of up to 0.9999,as well as the output current's total harmonic distortion of only 2.37%.(4)A high-efficiency energy-feedback DC electronic load prototype is developed,and the experimental platform is built for the testing of signal sampling accuracy,load simulation accuracy,grid-connected power quality and overall efficiency.The experimental results show that the high-efficiency energy-feedback DC electronic load prototype can work normally,which proves the design scheme is correct and feasible;the load simulation is held out to be accurate for the fact that the maximum relative error of the constant current load mode is only 4.50%,and the dynamic response performance meets the requirement of dynamic load simulation;the response time of the system fault protection is only 72.0?s,which ensures the safety of the equipment;the quality of grid-connected power is good,the output current's total harmonic distortion of 2800 W input power is as low as 2.403%,and the power factor is as high as 0.998;The overall efficiency of prototype is up to 96.03%,so as to minimize energy consumption and cost during the test. |
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