Hybrid Phase-Shift Control in Interleaved PFC Converters for EMI
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Solution Overview
Problem
Existing interleaved power factor correction (PFC) converters face challenges in effectively reducing electromagnetic interference (EMI) due to fixed phase-shift angles that fail to suppress differential mode noise across varying switching frequencies, particularly in critical conduction mode operations.
Innovation Solution
Implementing a hybrid phase-shift control method that dynamically adjusts the phase-shift angle based on switching frequency thresholds, using different phase-shift angles (θA and θB) to suppress specific harmonic currents, thereby reducing differential mode EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed phase-shift angle is used in interleaved PFC converters, then the control method is simple, but differential mode noise cannot be effectively suppressed across varying switching frequencies
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed phase-shift angle to a dynamic, frequency-dependent phase-shift angle. The controller adjusts the phase-shift angle between first and second interleaved PFC converters based on the detected switching frequency, enabling the system to adapt to varying operating conditions and effectively suppress differential mode noise across different frequency ranges.
Solution Approach 2:
The patent implements parameter changes by modifying the phase-shift angle parameter according to switching frequency thresholds. When the switching frequency exceeds a threshold, the controller changes the phase-shift angle from a first value to a second value, optimizing noise suppression performance across different operating frequencies.
2Object-affected harmful factors
If the phase-shift angle is dynamically adjusted based on switching frequency, then differential mode noise is suppressed effectively, but the control system complexity increases
Solution Approach 1:
The patent employs feedback by using the controller to detect the switching frequency of the interleaved PFC converter and adjust the phase-shift angle accordingly. This closed-loop feedback mechanism enables automatic adaptation to frequency variations while maintaining effective noise suppression.
Solution Approach 2:
The patent applies segmentation by dividing the frequency range into different segments with distinct phase-shift angle settings. The controller compares the detected switching frequency against thresholds and applies appropriate phase-shift angles for different frequency segments, simplifying the control logic while maintaining effectiveness.
3Device complexity
If fixed phase-shift angles are used, then device structure is simple, but EMI performance is insufficient across varying operating conditions
Solution Approach 1:
The patent transforms the static device structure into a dynamic system where the phase-shift angle can be adjusted in real-time based on switching frequency. This dynamic capability enables the device to maintain optimal EMI performance across varying operating conditions without requiring complex hardware modifications.
Solution Approach 2:
The patent achieves multi-functionality by enabling the same device structure to operate effectively across different frequency ranges through controlled parameter adjustment. The interleaved PFC converter with frequency-dependent phase-shift control can suppress differential mode noise at various switching frequencies, making the device universally applicable across different operating conditions.
Data Source
AI summary
A method of operating a circuit is disclosed. The method includes providing an interleaved power factor correction (PFC) converter circuit; determining a switching frequency of the interleaved PFC converter circuit; setting a phase shift of the interleaved PFC converter circuit at a first phase shift when the switching frequency of the interleaved PFC converter circuit is below or at a first switching frequency; setting the phase shift of the interleaved PFC converter circuit at a second phase shift when the switching frequency of the interleaved PFC converter circuit is greater than the first switching frequency but less than a second switching frequency; and setting the phase shift of the interleaved PFC converter circuit at the first phase shift when the switching frequency of interleaved the PFC converter circuit is greater than the second switching frequency.