diksha.k
Member level 5
I have already made a buck converter for my solar panel rated at 20V ,75W panel.
I wanted to design MPPT charger and specs are:
220uH inductor toridial iron powder core I have used and usind inductor chart and online calculator have put required turns on inductor well this converter works on 20Khz frequency.
The circuit diagram is shown below where:
555 timer circuit in astable mode is used as doubler circuit which powers tlp250.
It's used to isolate uc signals and power signals also doubler circuit provides sufficient Vgs on voltage for the high end MOSFET(called so because this IRFZ44N mosfet is connected before the load).
My logic for MPPT algorithm analysis as discussed earlier with few edaboard members and also I performed a expt taking a High wattage rheostat and went on loading the panel for maximum power and could find out that for various instants in day the max power delivered by the panel is only and only at a specific voltage of the panel and in my case it turned out to be ""around 14.85V""(though there may be error of +/-0.25V).So, myy algorithm also deals with keeping panel voltage around 14.85V only....
Now my problem is:I have hooked up everything as per diagram and also program is just a simple loop which reduces on time of 50us time period(20Khz frequency) by increasing pwm from 1 to 1022 but, results I have got are improper the word file with results displayed shows pwm is varying but, the voltage sits at open circuit voltage and only at around pwm=900 the voltage reduces to 14.9V or below(can be seen in that pdf).
Now this all was carried out when battery voltage =12.3V also some bulbs via inverter connected which inturn load the panel.
My doubts are:
1) The panel voltage come down if can see from 18V/19V(open circuit) to 14.5V or so. This happens with just one increment in pwm i.e say from 899 to 900.
I also found that tlp250 was supplying 8V for proper turning of mosfet only for pwm =900 and above. Below these when pwm=500 or 300 or 600 etc.. below 900 panel voltage just sat at voc.
Actually the hardware has to precisely follow any voltage in between the desired (14.85V) to open circuit voltage for every pwm change no?I have listed series of collected data in the word file
wm,solar i/p voltage,current,power.
2) This sudden change in voltage doesnot justify my algorithm as well because there is always a collective drop of 1.5V b/w mosfet drains-source+inductor whereas I had designed inductor to sustain drop of around 3-4V which isn't happening and drop is only 50mV.
I suspect that tlp250 isn't giving out voltage properly for desired pwm at a given frequency how can I rectify with such a situation?
I have added image of inductor as well:
though i didnt had the image with 52turns(recent one) but I have wound on same core:
**broken link removed****broken link removed**
image of circuit diagram
pdf of data collected:
**broken link removed**
I wanted to design MPPT charger and specs are:
220uH inductor toridial iron powder core I have used and usind inductor chart and online calculator have put required turns on inductor well this converter works on 20Khz frequency.
The circuit diagram is shown below where:
555 timer circuit in astable mode is used as doubler circuit which powers tlp250.
It's used to isolate uc signals and power signals also doubler circuit provides sufficient Vgs on voltage for the high end MOSFET(called so because this IRFZ44N mosfet is connected before the load).
My logic for MPPT algorithm analysis as discussed earlier with few edaboard members and also I performed a expt taking a High wattage rheostat and went on loading the panel for maximum power and could find out that for various instants in day the max power delivered by the panel is only and only at a specific voltage of the panel and in my case it turned out to be ""around 14.85V""(though there may be error of +/-0.25V).So, myy algorithm also deals with keeping panel voltage around 14.85V only....
Now my problem is:I have hooked up everything as per diagram and also program is just a simple loop which reduces on time of 50us time period(20Khz frequency) by increasing pwm from 1 to 1022 but, results I have got are improper the word file with results displayed shows pwm is varying but, the voltage sits at open circuit voltage and only at around pwm=900 the voltage reduces to 14.9V or below(can be seen in that pdf).
Now this all was carried out when battery voltage =12.3V also some bulbs via inverter connected which inturn load the panel.
My doubts are:
1) The panel voltage come down if can see from 18V/19V(open circuit) to 14.5V or so. This happens with just one increment in pwm i.e say from 899 to 900.
I also found that tlp250 was supplying 8V for proper turning of mosfet only for pwm =900 and above. Below these when pwm=500 or 300 or 600 etc.. below 900 panel voltage just sat at voc.
Actually the hardware has to precisely follow any voltage in between the desired (14.85V) to open circuit voltage for every pwm change no?I have listed series of collected data in the word file
wm,solar i/p voltage,current,power.2) This sudden change in voltage doesnot justify my algorithm as well because there is always a collective drop of 1.5V b/w mosfet drains-source+inductor whereas I had designed inductor to sustain drop of around 3-4V which isn't happening and drop is only 50mV.
I suspect that tlp250 isn't giving out voltage properly for desired pwm at a given frequency how can I rectify with such a situation?
I have added image of inductor as well:
though i didnt had the image with 52turns(recent one) but I have wound on same core:
**broken link removed****broken link removed**
image of circuit diagram
pdf of data collected:
**broken link removed**
Last edited: