Continuous Current Extraction Mechanism: Redefining The Capacitor Requirements Of Power Factor Correction Devices

In today's pursuit of high power density and long system life, the electrolytic capacitor bank in traditional power factor device systems has become a technological bottleneck. As topologies evolve from intermittent to continuous current draw, can this capacitor dependency be overcome?

Design Paradox: To achieve a high power factor, large-capacity electrolytic capacitors are necessary for energy buffering; however, the short lifespan of these capacitors directly restricts the reliability of the entire system. The theoretical breakthrough of the power factor improvement device device, which can reduce capacitance through continuous current draw, is driving a fundamental change in this situation.

Topology Innovation in Continuous On-Mode

The Boost-type inverterless parallel active filter adopts a direct AC-AC conversion architecture, combined with even-order harmonic modulation technology, which can completely eliminate the bulky electrolytic capacitor on the DC side while achieving reactive power and harmonic compensation. Compared to buck converters, the grid-side current of the boost topology exhibits continuous characteristics, meaning that no additional grid-side filter is required. Leading-edge modulation technology in the control chip further improves the available bandwidth of the PFC error amplifier, significantly reducing the capacitance requirement of the PFC DC bus capacitor.

Engineering Balance Between Capacitor Value and System Reliability

The reduction of output capacitance is not unlimited. By appropriately distorting the input current waveform, the theoretical limit for reducing output capacitance can be derived while meeting the EN 61000-3-2 harmonic standard. For applications such as high-brightness LED drivers, the lifespan of electrolytic capacitors often becomes a bottleneck in the entire system; reducing capacitance means that long-life film capacitors can be used as replacements. Continuous current-taking operation combined with a synchronous reference frame control algorithm allows the power factor correction device to achieve a better balance between dynamic response speed and power density.

The control strategy in continuous conduction mode also affects capacitor selection. The phase lead current reduction technology under light load conditions eliminates the phase lead current effect caused by EMI filters and input capacitors by correcting the average inductor current reference value, maintaining a high power factor over a wide load range while avoiding excessive increase in output capacitance to compensate for dynamic performance.