An Active Power Filter (APF) is a new type of power electronic device used for dynamically suppressing harmonics and compensating reactive power. It can compensate for harmonics of varying magnitudes and frequencies, as well as reactive power fluctuations, hence the name "active."

The Active Power Filter is a new type of power harmonic control equipment, manufactured using modern power electronic technology and digital signal processing techniques based on high-speed DSP devices. It consists of two main parts: the command current computation circuit and the compensation current generation circuit. The command current computation circuit monitors the current in the lines in real-time, converts analog current signals into digital signals, and sends them to a high-speed digital signal processor (DSP) for processing. It separates harmonics from the fundamental wave and outputs driving pulses to the compensation current generation circuit in the form of pulse-width modulation (PWM) signals. These signals drive IGBT or IPM power modules, injecting a compensating current into the grid with an amplitude equal to the harmonic current but opposite in polarity, thereby compensating or canceling out harmonic currents and automatically eliminating power harmonics.

The input and output terminal connection mechanism of the active power filter: composed of flame-retardant ABS terminals, copper bars, and fixing screws. Fixed screws are used to securely connect the flame-retardant ABS terminals with the corresponding grade of copper bars; the copper bars are equipped with both internal and external mounting holes; these holes are used to mount the mechanism onto the outer frame of the converter within the active filter, serving as an internal-external connection. This innovative structure is concise, cleverly designed, logically arranged, and offers a firm and stable connection. It boasts safe and reliable performance with flexible operability, demonstrating significant effectiveness.