HARMONIC REDUCE SYSTEM AND UNINTERRUPTIBLE POWER SUPPLY INCLUDING SAME

Some aspects of the present disclosure provide a harmonic reduce control system for controlling an inverter, including a phase-locked loop controller, a voltage sum loop controller, a repeative controller, a current loop controller, and a harmonic obtaining module. The harmonic obtaining module detects a harmonic value of a load current. The control system generates an inverter current reference value based on a first current value output by the voltage sum loop controller and the harmonic value, calculates a real-time frequency value based on a voltage of the power grid, obtains, through calculation, a repeative controller output value based on the inverter current reference value, the inverter output current, and the real-time frequency value, and outputs a first duty cycle based on the repeative controller output value. The control system limits the inverter output current based on the first duty cycle.