An active power filter is a new type of power electronic device used for dynamically suppressing harmonics and compensating reactive power. It can compensate for harmonics that vary in both magnitude and frequency, as well as reactive power fluctuations.
An active power filter is essentially a power source that provides the harmonic current required by the load, thereby reducing its impact on the power grid and other equipment. As awareness of the hazards of harmonic currents grows, virtually all new projects now incorporate active power filters. Moreover, with the increasingly compact structural design and higher power density of APF technology, the modular products like the iNAS-MA series are now widely recommended in the construction sector. Individual compensation capacities include 30/50/75/100/150, etc.

Based on the difference in the energy storage elements on the DC side of the main circuit of the active power filter, the types of APF (Active Power Filter) can be divided into: voltage-type APF and current-type APF.

An Active Power Filter (APF) is a new type of power electronic device used for dynamically suppressing harmonics and compensating reactive power. It can quickly track and compensate harmonics of various sizes and frequencies. The term "active" refers to its ability to actively control and output the magnitude, frequency, and phase of current, as opposed to passive LC filters that can only absorb fixed-frequency and magnitude harmonics. The APF achieves this by sampling load current and separating different harmonics and reactive power, thereby actively offsetting the corresponding current in the load, enabling dynamic tracking compensation. It can also compensate for harmonics, reactive power, and unbalance simultaneously.

Active filters are available in three types: cabinet-style, wall-mounted, and modular.
Active Filter: Composed of an operational amplifier and R, C elements, featuring advantages such as no inductors, small size, and light weight. The operational amplifier has a high open-loop voltage gain and input impedance, with a low output resistance. After forming an active filter circuit, it also provides certain voltage amplification and buffering functions. However, due to the limited bandwidth of the operational amplifier, the working frequency of the current active filter circuits is difficult to achieve high frequencies.