APF Principle
Delta’s PQC Series APF is connected in parallel with non-linear loads, and uses one set of current transformers (CT) to detect the load current. It calculates each order harmonic current by FFT algorithms in its DSP microchips, and then generates a compensating current with the same amplitude but opposite phase angles to the detected harmonic current, which cancels out the original load harmonics.

The PQC series APF not only eliminates harmonic current from the load side, but it also mitigates harmonic voltage caused by harmonic currents. The APF system can also improve power factor (PF) and correct load imbalances in the power system.

Note: CT is a critical part of the APF system, and it can be purchased by users themselves, following Delta’s suggestions on CT specification.

PQC APF Principle

APF Structure

Delta PQC Series APF has a modular design, which adopted 3-level inverter topology with 3 pcs modular IGBT and DC capacitor components, and the Delta Active Power Filter system consists of one or several APF modules and a 7'' or 10'' HMI display.

Each APF module is an independent harmonic filtering system, and users can change the harmonic filtering system rating by adding or removing APF modules.

According to the mounting type, Delta PQC series APF can be divided into Modular APF (rack mounting) and wallmounted APF.

APF Module and Cabinet Solutions

According to cable terminal type, a modular APF can be divided into two types:.

Drawer type modular APF (adding pluggable accessories on power cable terminals)
Mixed fixed type modular APF (Power cables are fixed from rear side, Signal cables are fixed from front side)