Low voltage active power filter APF

RAPF is a new power electronic device with high controllability and fast response, which can automatically track the harmonic changes of power grid. It can be used to dynamically suppress harmonics, compensate reactive power, and compensate harmonics and reactive power with varying size and frequency. APF overcomes the shortcomings of traditional passive filter, such as poor filtering effect, easy to resonate and can only compensate fixed order harmonics. APF can play a better filtering and compensation effect for all kinds of fast transient impulse loads.

Advantage comparison between APF and passive filter


Passive filter


Basically no maintenance required

Replace the capacitor regularly

Compensation efficiency


60~70%, it is greatly affected by power grid parameters

Filtering order

2~50th harmonics can be compensated, and each harmonic compensation capacity can be set

Fixed order harmonic compensation


No resonance

Nonlinear load is easy to resonate, leading to harmonic amplification, and capacitor is easy to bulge or even burn out

Reactive power compensation accuracy

High accuracy and continuous adjustment

Generally, there are several tens of kvar, which are prone to be over compensation or under compensation

Compensation capacity

Inductive 100% - capacitive 100%, not affected by grid voltage

Only capacitive reactive power can be compensated, and the actual compensation capacity is about 80% of the nominal capacity

Product technology advantages

NPC type three-level topology, lower loss, smoother output waveform

Independent air duct design. Greatly increase the heat dissipation efficiency of the system, and significantly enhance the adaptability of the system to dust and salt mist

Resonance suppression and monitoring. Active damping algorithm and passive damping design are simultaneously used to suppress resonance.

Harmonic compensation of each order can be set independently

The fan can adjust speed automatically. The cooling fan automatically adjusts the wind speed according to the compensation current and IGBT temperature, which greatly improves the fan life and effectively reduces the system noise

Over temperature automatic capacity reduction. When the IGBT temperature exceeds the threshold, the system will automatically reduce the compensation current to ensure the safety of the system under the extreme working conditions such as fan blocking, filter net blocking and excessively high ambient temperature.

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