Control device applied in power factor correction power converter and control method thereof

Abstract

The invention relates to a control device applied in a power factor correction power converter and a control method thereof. The control device is used for reducing the change rate of a reference signal with an ascending part and a descending part when an input voltage approaches zero potential. When a main winding releases approximately all stored energy and the descending part of the reference signal reaches a condition, the control device turns on a changeover switch to increase the stored energy of the main winding.

Description

technical field [0001] The present invention relates to an AC to DC converter architecture, in particular to an AC to DC converter architecture with power factor correction (power factor correction, PFC). Background technique [0002] In most AC-to-DC converters, it is desirable to have the entire circuit exhibit a purely resistive behavior with respect to the AC input voltage. For this reason, many active PFC architectures have been developed today, and these PFC architectures can generate a corresponding AC input current when receiving an AC input voltage. [0003] For PFC, it is very important to generate a sine wave current with very low total harmonic distortion (THD). THD and power factor represent the operational performance of the PFC circuit. The highest value of power factor is 1, and in general practice, THD is acceptable as long as it is lower than 15%. [0004] For example, US Patent Nos. 7,375,995, 7,397,678, re40016, and 7,295,452, etc. all disclose part of...

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Problems solved by technology

[0007] However, even if the on-time increases slightly with the shortening of the off-time, once the off-time is too short, it will cause unnecessary high-frequency switching energy loss (switching loss)

Moreover, the on-time changes with the off-time (off-time), which may increase the THD instead

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