ACTIVE FILTER FOR COMPENSATING POWER CONVERTER-GENERATED HARMONIC CURRENT

摘要

PURPOSE:To improve harmonic compensation effect by controlling an active filter through a signal from a control angle-harmonic current conversion circuit. CONSTITUTION:A control angle-harmonic current conversion circuit 3 generates a harmonic current signal with the magnitude and phase of harmonic which is previously generated in the manner of corresponding to each firing control angle. Then, an active filter composed of firing control angle determination circuit 2, phase inverter 8, hysteresis comparator 5, inverter 6, transistor Tr, injection circuit 9, etc., is controlled by a signal from this conversion circuit 3, and a harmonic current generated by this active filter is injected into a system line 1 to compensate harmonic current generated in a harmonic-generating load 1. Thus, it is possible to eliminate a time lag from the detection of load current to the determination of control angle to improve harmonic compensation effect.