Ok Gordon, I should have said 'highest converter output current' just to make clear I am not talking panel output current! The converter output voltage and the product power is actually not necessary Isaac! I can already start to see it could be done with optimistcally one op amp and a variety of RC combinations! The pseudocode I think will work: D=3DFeedbackScanVoltageStep (Positive or Negative) F=3DFeedbackVoltage loop: P=3DPreviousOutputCurrent(A) F+=3DD A=3DMeassureOutputCurrent() if(A>P) Direction might be good, continue loop else D=3D-D, continue loop Of course the OpAmp implementation would be analog, one capacitor will hold the seek direction Up or down, via resistor the feedback voltage will have to be integrated on the capacitor on the XL6009 feedback input. one comparator evaluates the tendency in the output current. The output swing of that comparator will have to charge or flip that direction memory capacitor. I am not very efficient though with op amps... Maybe somebody can confirm my ideas or teach me some realism? For example I might have overlooked the dynamic signal content on the feedback pin that is used to deduct the actual PWM width, after all I see no other conversion frequency defining components ... cheers Tobias On 2/23/15, Gordon Williams wrote: > What Harold said is the maximum power point occurs at roughly a constant > *voltage* from the solar panel. That is somewhere between zero and max > voltage output. > > You are talking about highest *current*, which is wrong. The highest > current will be when the solar panel is short circuited and produces no > power. > > What you can do is take you panel and measure voltage and current from > it under various loads to characterize the panel output. Knowing these > two values you can graph the power output and determine the peak power > output voltage under sun and shade conditions. You can then confirm > what Harold is saying is true. You can then use this info to design your > MPP. > > Gordon Williams > > > > > On 15-02-23 08:34 AM, Tobias Gogolin wrote: >> Thanks Harold! >> MPP is definitely is around highest output current, however I see no >> simple way to adjust feedback based on something that must be >> dynamically sought up and down? >> Constant input is just not a given when thinking about the moving >> shades and reflections a moving vehicle is exposed to all the time! >> However you do touch an important issue, as the normal circuit would >> in the effort to achieve output target, possibly drag the input down, >> way out of the MPP range! >> >> Let me see what you guys think about this type of pseudo code for the >> MPPT algorithm: >> >> D=3DFeedbackScanVoltageStep (Positive or Negative) >> F=3DFeedbackVoltage >> loop: >> P=3DPreviousOutputCurrent(A) >> F+=3DD >> A=3DMeassureOutputCurrent() >> if(A>P) Direction might be good, continue loop >> else D=3D-D, continue loop >> >> >> >> On 2/23/15, Harold Hallikainen wrote: >>> One clever thing I learned from Linear Technology is that the maximum >>> power point is very close to a constant voltage out of a solar panel. >>> So, >>> a very simple MPPT converter is a constant voltage converter where you >>> take the feedback from the INPUT instead of the output. The switcher >>> adjusts the duty cycle as required to keep the input voltage constant. >>> >>> Harold >>> >>> >>> >>> >>> -- >>> FCC Rules Updated Daily at http://www.hallikainen.com - Advertising >>> opportunities available! >>> Not sent from an iPhone. >>> -- >>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >>> >> > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 Tobias Gogolin Tel. D1 (49) 0151 5187 5210 Tel. D2 (49) 0152 0839 5060 skype: moontogo messenger: usertogo@hotmail.com You develop Sustainable Ranch Technology at http://tech.groups.yahoo.com/group/SURA-TECH an Open Source Electric Motor/Alternator at http://groups.yahoo.com/group/Performance_Axial_Flux and an Open Source Motor Controller at http://groups.yahoo.com/group/GoBox --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .