I am using boost converter between PV panel and load (RL) acts as an interface to operate at MPP, so the equivalent input resistance (Req) of the converter as seen by the PV module can be obtained as follow
Req = (1-D)² RL Where, D is the duty cycle
So, based in the above equation, whatever the value of RL (where RL > Rmpp), The MPPT will compute a duty cycle which can give a Req equals to Rmpp in order to track the peak power.
I would like to know if that is correct or not ?
Thank you,
Dear Saad Motahhir,
Yes it is correct. Suppose that you're using the classical MPPT technique, that is P&O algorithm. Variation of RL alters the PV power output and as the duty cycle is continuously perturbed by the MPPT algorithm, a decreasing of power will be detected and the algorithm will vary the duty cycle in a way to increase the power and eventually converge to the right Req=Rmpp .
hope my answer was useful.
Yes it is correct. The load resistance (Rl) must be larger than Rmpp at any atmospheric conditions (temperature and radiation).
Thank you all, but how different loads will absorb the same power? because each load can support different value of power !
The load will absorb the maximum power. This power as you know keep changing with the variable atmospheric conditions. Your load must handle the maximum available power at standard test conditions (STC).
Thank you dear,
if we use two loads ( RL= 50 ohm and RL= 30ohm), and they absorb the same maximum available power at standard test conditions (STC). That is correct ?
Yes it is correct. As long as the resistors (30&50) satisfy the condition Rl>Rmpp at STC.
Req = (1-D)² RL is correct when the boost works at the CCM.
When the boost works at the DCM, it is not correct
but what if we want to use DC-AC stage for grid tied application..? because by varying duty cycle, the output voltage will vary. hence dc link voltage will vary. but for grid tied inverter dc link should be constant (if i am not wrong..!). then what should be done..?
The load will absorb the maximum power. This power as you know keep changing with the variable atmospheric conditions. Your load must handle the maximum available power at standard test conditions
Please refer to these articles:
https://www.researchgate.net/publication/309716325_Designing_And_Simulating_Of_Micro-controller_Based_on_PWM_Solar_Charge_Controller
https://www.researchgate.net/publication/315692275_Maximum_Power_Point_Tracking_Control_of_PV_Electronic_System_using_Neural_Network
Article Designing And Simulating Of Micro-controller Based on PWM ...
Conference Paper Maximum Power Point Tracking Control of PV Electronic System...
Dear Saad Motahhir,
it is correct when your converter operating at CCM.
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