Active electric filtering device

The utility model discloses an active electric filtering device, comprising a current conversion circuit, an instruction current arithmetic circuit, a compensating current occurrence circuit, an automatic limiter circuit and a display-operating controller. The instruction current arithmetic circuit is composed of a first 2 phases/2 phases coordinate converter and a second 2 phases/2 phases coordinate converter which are respectively connected with a sine occurrence circuit and a cosine occurrence circuit connected in manner of phase-locked loop; a 3 phases/2 phases coordinate converter is connected with a first low-pass filter and a second low-pass filter in parallel by the first 2 phases/2 phases coordinate converter, and the second 2 phases/2 phases coordinate converter is connected with a 2 phases/3 phases coordinate converter; a n-times doubling circuit which is connected in front of the phase-locked loop is also included, the n-times doubling circuit converts power supply voltage ea to frequency signals, the frequency signals magnifies for n times, and n subharmonic currents are obtained.