An active power filter is responsible to provide power to loads while compensating for non-linearities and reactive power, that can degrade the main supply wave-form. It is also able to operate as an uninterruptible power supply
The topology consist of an active rectifier, supplying a battery bank. After that, the three-phase inverter is able to supply a load without reactive power or harmonics from the main.
The control loop is performed by a lead-lag controller.