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SM72445EVM: Why does the SM72445EVM can not approach the maximum power

user4869738
Prodigy 20 points
Part Number: SM72445EVM


Hi，

I wish to track the maximum power of Thermoelectric Generator(TEG).(Voc=17V I=200mA) The output is connected with an Electronic Load。

First，I connected the Thermoelectric Generator(TEG) with Electronic Load directly。I changed the resistance value of  Electronic Load （it worked at constant resistance mode），and found that the maximum output power of TEG was 2.42W，the value of resistance was about 40Ω。

Then ，I connected the TEG with the input of the SM72445EVM。The output of the EVM was connected with Electronic Load。When Electronic Load worked at constant voltage mode，the EVM can not enter MPPT mode until the load voltage was below 7V。In MPPT mode the load power changed rapidly，and can just approach 1.05W; When Electronic Load worked at constant resistance mode,the EVM can not eater MPPT mode until the load resistance is about 20Ω.The load can not approach the ideal power。I want to know why，and how can I use this EVM?

Thanks for your help. This project is very important for me

Shuo Wang

 

  • 0
    TI__Guru* 78630 points
    Do you mean you operate the 300W EVM with <3W power? You have to scale the current resistor value up a lot to have reasonable signal magnitude, or it will not work well owing to resolution limit.
  • 0 in reply to Youhao Xi
    Prodigy 20 points

    Thanks for your reply。 According to your answer，I would like to know：

    1、How to scale the current resistor value？ I have changed the  current resistor in output（R10 in EVM）from 0.004Ω to 0.2Ω，but the EVM still work not well。

    2、I an going to use constant voltage source to simulate Thermoelectric Generator(（TEG） as input source，is it reasonable？ My colleague think that  the output current of constant voltage source may be increasing to keep its output voltage of constant ，what do you think of it？

    Looking forward to your reply，thanks again

    Shuo Wang