CIRCUTOR AFQ Series - Manual (Page 36)

AFQ-4W
36 Instruction Manual
4.1.5.- OPERATING PRINCIPLE
Active filters are based on the following principle:
I
FILTER
= I
MAIN
- I
LOAD
Equation 6: Operating principle
In other words, they detect the difference between the required current sine
wave (I
MAIN
) and the signal deformed by the harmonics (I
LOAD
). And they inject
the difference between both waves (I
FILTER
).
Figure 32 show the wave shapes of the currents injected by the active filters.
These show the required wave, the existing deformed wave and the filter current
(I
FILTER
).
Figure 32: Current in the load, in the filter and in the mains.