Paralleling of active filters with independent controls
A parallel filter arrangement with at least two filters supplying current in line side sensing configuration and a number of sensors for measuring current. The sensors are used to determine the amount of current being supplied by the filters and the amount of current being supplied by a source. The filters adjust their supplied current in order to reduce or eliminate the amount of reactive or harmonic current being supplied by a source.
1. A method of reducing circulating current between two line side sensing electronic active filters in an electrical system including a current source supplying current to a load, the method comprising:
sensing a current from the source;
generating a first current component and a second current component;
sensing the first current component and the second current component;
determining a difference between the first current component and the second current component;
comparing the difference, the current from the source and a filter reference signal to arrive at a comparison;
adjusting the first current component using the comparison and the sensed first current component; and
adjusting the second current component using the comparison and the sensed second current component.
2. The method of claim 1 , wherein the adjusting the first current component additionally uses the sensed first current component.
3. The method of claim 2 , wherein the adjusting the second current component additionally uses the sensed second current component.
4. A method of filtering a current drawn by a load from a current source providing a current in an electrical system having a first line side sensing electronic active filter and a second line side sensing electronic active filter, the method comprising:
sensing the current from the current source;
generating a fundamental current component and a harmonic current component from the current sensed from the current source,
supplying at least a portion of the harmonic current component from the first line side sensing electronic active filter, by means of supplying a first current component;
supplying at least a portion of the harmonic current component from the second line side sensing electronic active filter, by means of supplying a second current component;
determining a difference between the first current component and the second current component;
comparing the difference, the current from the current source and a filter reference signal to arrive at a comparison signal;
adjusting the first current component using the comparison signal and the sensed first current component; and
adjusting the second current component using the comparison signal and the sensed second current component.