Power optimizer is an end equipment that usually used along with string inverter. The power optimizer provides module level monitoring function, rapid shut down function and module level MPPT function which improves the PV system safety and helps generate more power for the whole PV strings, especially when the strings are in partially shaded and other abnormal situations.

Power optimizer uses common topologies of Buck and 4-switches Buck-Boost. The buck topology usually uses low-side current sampling by shunt resistor and amplifier. While the 4-switches Buck-Boost usually uses high-side current sampling. The input of optimizer is connected to one PV panel or two PV panels in series, the common-mode voltage can be up to 150V with 2 PV panels in series. In-package hall-effect current sensor is a good choice for the 4-switches Buck-Boost optimizer, as shown in Figure 2-11. The inductor current is sampled for current loop control and protection purposes.

Figure 2-11 4-Switches Buck-Boost Optimizer Block Diagram With Hall-effect current Sensor