boost converter not working with pv source

[crimo]

my boost converter works well with dc supply
but doesnt work properly with a solar panel instead the voltage is reduced instead of increasing.i used IR2101 for the mosfet driver
and using an N channel 19N20 mosfet for swithcing

 

[KlausST]

Hi,

just giving the dirver name and the MOSFET name is no meaningful information for us.

We need a schematic, specifications, voltages, currents, frequencies, duty cycle ... and so on. A picture of your PCB is also good.

Klaus

 

[FvM]

Presumed the boost converter is working well (without excessive losses), you may be simply operating the solar panel below the maximum power point.

 

[crimo]

input voltage 17.3v
output voltage 24v
D=0.27
frequency 20khz (using arduino uno)
L=243.4μH
C=10μF

this is a prototype so designed on a bread board. the results are almost perfect with dc power supply but with the pv panel which it reduces the voltage. i understand that if you try to implement MPPT with this topolgy you cannot track if the voltage is close to the open circuit so i have varies the light source so the input voltage is low around 8v but the result is the same

 

[BradtheRad]

input voltage 17.3v
output voltage 24v
D=0.27

In a boost converter, the power supply is always in the loop of current flow. Therefore the PV panel is always providing current. Does the PV panel produce sufficient Amperes? Even if it does, the likelihood is that you need to increase the duty cycle.

To look at it another way: The PV panel has an internal resistance. If it is high, you will not get much watts out of it.

 

[crimo]

I have tried varying the duty cycle but as I increase the duty cycle the voltage is reduced more.

 

[dick_freebird]

Have you looked at the input voltage with a 'scope to
see whether the panel is sagging against the inductor
current ramp? Maybe you need more bulk input decoupling
to ride out the inductor charging phase, that just might
happen to show up for free with the power supply? Do
you measure inductor and input and output currents
in all of this?

More duty increases inductor current, but off time is when
that current is transferred to the load. Too little off time
(more duty) can decrease the transfer of all that inductor
current goodness rather than increase it. This is a bad thing
for a classical control loop, effectively a phase inversion
(more duty = less voltage being the opposite of the intent
and the control loop paradigm). There is a sweet spot that
wants figured out, and control loop windup past this point
prevented.

 

[Easy peasy]

you have lots of issues, firstly you need very bright illumination of your PV, how many watts is it? unless you have good MPPT control of you booster you run the risk of trying to draw too much power which will pull the PV volts down always.

you need a manual control from 0% PWM up so you can see for your self the V & I out of your panel....and a constant resistance (but adjustable) load, from slight load to full power of the PV panel.

 

[treez]

also, linear.com have smps control chips which are for solar panel input..they can pass power to output based on regulating either their input voltage , or input current.

 

[FvM]

I don't believe that it's a problem of using a specific "chip". Need to understand the requirements imposed by the solar panel power source and implement a suitable control method.

The reports are lacking many essential informations:
- solar panel I/V characteristic at actual irradiation level
- boost converter design details, e.g. does it have a sufficient input capacitor
- load

To verify correct operation of the boost converter, you should determine input and output DC current along with the voltages and calculate efficiency.

 

[treez]

True, does OP appreciate that solar panels have a considerable output resistance, when OP realises that, I think OP will be fine.

 

[crimo]

Yep just realized about the resistance and was only measuring output voltage before and after turning on mosfet driver.not realizing the input voltage was less after turning the mosfet driver with a fixed 10 volts dc supply.hence the need for MPPT.thanks for all the advice