I will design MPPT solar charge controller and understand that by manipulating the load impedance seen from the solar panel (reducing the duty cycle of the buck converter), the input voltage to the DC-DC converter (from the solar panel) will increase as the load current will also increase with constant voltage output( the load being the battery). The charge controller will minatan the duty cycle where the load current stop increasing as this is to be the maximum point. The problem is I want the output voltage to be relatively controlled or constant while the load current increasing . How the output voltage is held constant while changing the duty cycle to increase the current? if the answer is by having a feedback loop that change the duty cycle, then this will interfere with reducing producer of the duty cycle to increase the current.
is it by desgening two loops, inner for current regulates the load current, outer loop keeping the output voltage constant?
You cannot simultaneously regulate output voltage while extracting maximum power from the PV array. Think about the energy transfer, and how it interacts with the source and load impedance. With both high source and load impedances, load and output current must be controlled to achieve MPPT and desired output voltage, yet these two are directly linked through the transformation ratio (duty cycle) of the DC/DC converter. In the case of charging a battery, you typically run the MPPT algorithm during bulk charge. Once the voltage reaches the point where you want to regulate at, a voltage control loop takes over, and you no longer operate at the maximum power point.
Mohamed Azab
but how the o/p voltage of dc-dc converter is constant while changing the duty cycle ? changing the input parameters through the duty cycle will also change the o/p voltage, right ? since this output voltage is being changed, then it might damage the battery.
Thank you for first replay.
You cannot simultaneously regulate output voltage while extracting maximum power from the PV array. Think about the energy transfer, and how it interacts with the source and load impedance. With both high source and load impedances, load and output current must be controlled to achieve MPPT and desired output voltage, yet these two are directly linked through the transformation ratio (duty cycle) of the DC/DC converter. In the case of charging a battery, you typically run the MPPT algorithm during bulk charge. Once the voltage reaches the point where you want to regulate at, a voltage control loop takes over, and you no longer operate at the maximum power point.
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