| Abstract |
Active power filters are used to eliminate ac
harmonic currents by injecting equal but opposite compensating
currents. Successful control of active filters
requires, among other things, an accurate current reference.
In this paper, we introduce a multistage filtering
structure which combines a lowpass prefilter and an adaptive
predictive filter, making it possible to extract the sinusoidal
active current from the distorted waveform without
harmful phase shift; even when the frequency and amplitude
change. Although active filters are typically used to
compensate for the supply harmonics, where the fundamental
frequency remains almost constant, we will show
that our filter structure can also be applied in applications
where the frequency alters rapidly. |
