US 5,691,626 A · 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.

Claims15

Dependent claims

An active damping control device for an active power filter, the device comprising:

a filter circuit comprising an inductor and a capacitor for suppressing noise in the active power filter, and a first current sensor system for sensing a three phase capacitor current of the capacitor;
a second current sensor system for detecting a three phase load current;
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 to dampen high frequency components of the active power filter.

An active power filter system comprising:

an active power filter;
and
an active damping control device comprising:
a filter circuit comprising an inductor and a capacitor for suppressing noise in the active power filter;
a first current sensor for sensing a capacitor current of the capacitor;
a second current sensor for detecting a load current;
an active power filter controller for calculating a reference current for the active power filter to dampen high frequency components of the active power filter, the active power filter controller including:
a voltage processing device for receiving a grid voltage and calculating a corresponding voltage angle;
first and second transform systems, each of the first and second transform systems for extracting the respective fundamentals of the capacitor and load currents, each of the first and second transform systems including
a first transformation device for transforming a three phase current into a stationary reference frame using the voltage angle and providing two transformed current signals representative of real and reactive power;
two low pass filters for filtering the high frequency components of the transformed current signals and providing filtered current signals;
two filter subtractors for subtracting a respective filtered current signal from a respective transformed current signal to obtain a respective differential current signal;
and
a second transformation device for transforming the differential current signals to a three phase output current;
and
a subtractor for subtracting an output current of the first transform system from an output current of the second transform system.

13 more elements

Dependencies are inferred from the claim text.

Active damping control for active power filter

Life of this patent

Active damping control for active power filter

Life of this patent

Abstract

Claims15