Research On The Analog Controller Of PV System Based On Equivalent Impedance Matching Method

Renewable energy has attached great importance all over the world, since the globalenergy security and climate issues are increasingly serious. Because the solar energy is aclean, non-polluting and renewable energy resource, more and more people pay closeattention to it. The photovoltaic power generation is one of the important forms of solarenergy utilization and maximum power point tracking is an effective way to improve theefficiency of the photovoltaic power generation.Firstly, the technology of maximum power point tracking is researched and thedynamic equivalent impedance adaptation method as the final algorithm is chose on thebase of comparing the several algorithms. EIM achieves maximum power point trackingby adjusting the impedance deviation to zero.Secondly, to verify the feasibility of the algorithm, simulate the maximum powertracking algorithm based on EIM algorithm by MATLAB simulation software. Then,considering the possible problems in the simulation, the basic analog circuit modules areconstructed in Pspice. The maximum power point tracking based on EIM is realized by theanalog method. In the paper, not only analyzing the characteristics of the circuit in analogcontrol and the selection of voltage direction in every module circuit, but also learning theanalog chips in the control circuit such as operational amplifiers, multipliers and so on.Furthermore, the parameters of the low pass filter circuit, adder circuit and differentialcircuit in the control strategy are analyzed and designed in detail. On this basis, applyingthe function of the circuit designed in Pspice, the circuits are simulated to verify that theycould achieve the desired control objectives and lay the foundation for experiment.Finally, each module schematic diagram is draw in Altium Designer10.0and themaximum power point tracking experimental platform is built. An MPPT experimentbased on equivalent impedance adaptation method is conducted on four series PV panels.In the experiment, comparing the sampled signal, filtered output signal and differentialcircuit signal with simulation results in order to validate the EIM control strategy iseffective and feasible by analog method. By comparing with the experiment of digital control strategy, prove the analog control is an excellent implementation. On the premiseof reducing costs, analog control has an ideal track performance. So it is worth using andpromoting.