Input Current Regulation Mechanism Of Power Factor Correction Device Under Continuous Current Control

Power electronic devices often exhibit pulse-type current waveforms at the AC input. Rectifier circuits and capacitor filtering structures can generate instantaneous large currents near the peak grid voltage. power factor device By continuously drawing current, the peak input current is reduced, making the current waveform closer to a sinusoidal shape, while simultaneously reducing harmonic components. This regulation method is widely used in the design of switching power supplies and power conversion systems, with the core objective of improving the quality of the input current waveform.

Continuous Current Drawing Mode Current Regulation Mechanism

power factor improvement device By continuously drawing current to reduce the peak input current, continuous current mode (CCM) is typically used in control strategies. In this operating state, the inductor current changes continuously throughout the switching cycle, and the current waveform does not drop to zero. The inductor's energy storage and release process remains stable in each switching cycle, resulting in a smooth change in the current drawn from the grid at the input.

The continuous current drawing structure changes the traditional method of concentrated power drawing near the voltage peak of the rectifier circuit. The current is distributed over a longer time interval, thereby reducing the amplitude of the instantaneous peak. The input current waveform changes synchronously with the grid voltage, thus reducing the degree of current distortion.

Implementation Path for Reducing Peak Input Current

capacitor bank for power factor improvement reduces the peak input current through continuous current sampling, the key being the control of the inductor current trajectory and duty cycle changes. The control chip adjusts the switching transistor drive signal in real time according to the input voltage, making the current envelope curve follow the voltage waveform changes.

In a Boost-type PFC topology, the rectified AC voltage is regulated by the inductor and the switching transistor. Under the action of high-frequency switching, the inductor current forms an approximately sinusoidal input current trajectory. This process changes the peak current structure of the capacitor charging after the original rectifier bridge, making the current uniformly distributed throughout the entire half-cycle.

The design concept of power correction device, which reduces the peak input current by continuously sampling current, is essentially an input current shaping technique. Current waveform adjustment, inductor energy conversion, and the coordinated operation of the control loop together constitute the core mechanism of input-side current regulation.