The smaller input voltage satisfying dVout/dVin=-1 is called the input low voltage VIL and the larger input voltage satisfying this condition is called the input high voltage VIH. Both these voltages play significant roles in determining the Noise Margins of inverter circuits.
[pdf] Essentially, a grid-following inverter works as a current source that synchronizes its output with the grid voltage and frequency and injects or absorbs active or reactive power by controlling its output current.
[pdf] Undervoltage protection ensures that the inverter operates within safe voltage limits, thereby avoiding potential issues caused by low voltage conditions. Low voltage can be as damaging as high voltage, leading to improper functioning and reduced efficiency of the inverter and connected devices.
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