APPARATUS FOR IMPROVING ELECTRIC QUALITY USING PASSIVE FILTER TO REMOVE PREDETERMINED HARMONIC CURRENT COMPONENTS

摘要

PURPOSE: An apparatus for improving electric quality is provided to reduce a response time to a harmonic current induced by a nonlinear load by using a passive filter for removing predetermined harmonic current components. CONSTITUTION: A current-voltage converter(20) detects a source current of an AC voltage source and a harmonic current generated by a nonlinear load and converts them to AC voltage signals. A first filter(30) includes plural band pass filters and performs band pass filtering on the AC voltage signal to output corresponding harmonic frequency signals. A second filter(40) includes plural passive filters which are parallel-connected between the AC voltage source and the current-voltage converter. The second filter removes the harmonic current generated at the nonlinear load. A control signal output unit(50) receives the output of the first filter and converts the received signal to DC voltage signals. The control signal output unit includes plural switching controllers for outputting switching control signals which are activated when the converted DC voltage reaches a predetermined voltage. A switch(60) includes plural control switches which receive the switching control signals and are turned on/off by the activation status of the switching control signals. The switch controls the passive filters according to the on/off status of the plural control switches.