Active damping control for active power filter

Abstract

An active damping control device for an active power filter includes a filter circuit having an inductor and a capacitor for suppressing noise in the active power filter; a first current sensor for sensing a three phase capacitor current of the filter capacitor; a second current sensor for detecting a three phase load current; and an active power filter controller for extracting the fundamentals of the capacitor and load currents and calculating a reference current for the active power filter. The active power filter controller can include a phase locked loop device or a notch filter for receiving a grid voltage and providing a corresponding voltage angle; first and second discrete fourier transform devices for using the voltage angle and the capacitor and load currents for extracting the fundamentals of the capacitor and load currents, respectively, and providing respective first and second output currents; and a subtractor for subtracting the first output current from the second output current to obtain the reference current. The active power filter can further include, situated between the first discrete fourier transform device and the subtractor, a multiplier for multiplying the first output current by a predetermined factor and a high pass filter for filtering the first output current. The filter circuit can include a circuit breaker coupling the inductor, the capacitor, and the first current sensor to the load for providing overcurrent protection to the filter circuit.