Observe & Perturb

The PO-method is the most commonly used algorithm for finding the MPP, its operation is explained using the state diagram from control flow diagram . First of all, the voltage $V_{pv}$ and current $I_{pv}$ at the solar module are measured and processed, then the current power is calculated, the power delta $P_{pv}$ and the voltage dela $V_{pv}$ with respect to the previous run. Then it can be checked whether the power delta has changed positively or negatively. If the power delta is larger, the next step is to find out if the voltage delta has also changed, and the reference $V_{ref}$ can be increased or decreased by the step size $dV$ accordingly. The algorithm runs on the microcontroller in an infinite loop, continuously optimizing the performance of the solar panel.

During implementation, it turns out that the PO-algorithm does not work together with the PI controller from chapter pid. When the maximum current flows out of the solar module, and then the duty cycle of the boost converter is further increased, the voltage at the solar module collapses because not enough current can be supplied, but the PI controller continues to increase the duty cycle to regulate to reference voltage, further worsening the situation. This leads to an unusable operating state, which the controller cannot leave by itself. For this reason, the duty cycle $d$ is set directly.

Control Flow Diagram