According to my experience, the most appropriate DC/DC converter topology to deal with MPPT systems powered by PV systems, is that the boost type: step up, SEPIC or Cuk. In the following link you will find information that may be helpful to you.
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There is no single best topology ... In general, the converters having continuous input current (like boost converter) are preferable from the PV array point of view. Depending upon the application at hand, you may or may not want to have galvanic isolation as well.. that also affects the life of PV array ..
For the same power, the transistors have a (2x) bigger peak to peak voltage, so there are more switching losses. Also more losses in the inductive components and capacitors.
The galvanic insulation is also an additional loss. This is as 4 times more transistores are needed at the same Ipeak*Vpeak rating to make AC compared to a chopper.One can also protect against contact with a residual current detector.
A galvanic insulation can be made using a soft switch converter.
Dear Mohammed, There are many converter topologies and every topology is analyzed researchers under various situations. Among the topologies Boost converter topology with MPPT is mostly adapted.
You should first decide your load and PV. According to the ratings of PV and load the converter may vary. Check the following link where the buck converter with MPPT is explained.
www.blueskyenergyinc.com/.../BSE_What_is_MPPT.pdf
Read the article to know about boost converter.
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There are a lot of topologies for PV applications. All of them have advantages and disadvantages. You'd better to choose from them in consideration of power levels, voltage levels and isolation requirement. Boost is OK when the voltage gain is less than 3.
For all MPPT strategies is important to have the possibility to control the input current of the converter, in order to obtain the MPP (you will find a lot of paper with the procedure to obtain this point).
So, the proper converter structure results from the input voltage you have from PV and the necessary output DC voltage (for storage, or for DC-AC conversion).
For high conversion ratio you can implement the "hybrid structures", Z converters etc. You can find such structures in our paper (attached in RG, with full text).
There is a difference between power extracted and power delivered to the grid...Indeed buck-boost can always follow, but has a bad efficiency: The voltage on the transistor in the buck-boost is the sum of input and output voltage, and so are the switching losses. Also the rms voltage on the inductor is larger, one needs a larger inductor, so also losses and costs there. The reason why MPPT uses the input power is that it is easier to program. In fact one should track the power to the grid. The converter efficiency is not constant.
Well the best option is to control the the amount of input current in the converter so as to achieve great MPPT thereby boost converter seem to be suitable for this purpose. Somewhat there are still remains some issues of of efficiency