Power Factor Correction Circuit THD Reduction
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Solution Overview
Problem
Existing power factor correction circuits face challenges in reducing total harmonic distortion (THD) across varying load conditions, requiring complex compensation strategies that are not universally applicable.
Innovation Solution
A power factor correction circuit and control method that adjust the on-time of the main switch based on measured THD, using a controller to inversely superimpose predetermined harmonic components on the input current, thereby minimizing THD without specialized compensation for specific factors affecting the THD index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If complex compensation control strategies are used to decrease total harmonic distortion, then THD reduction is achieved, but device complexity increases
Solution Approach 1:
The patent extracts and compensates only the predominant harmonic components (5th and 7th harmonics) rather than attempting to compensate all harmonics. By identifying and targeting the most significant harmonic sources, the control strategy achieves effective THD reduction while maintaining manageable complexity.
Solution Approach 2:
The patent applies different compensation strategies for different harmonic components based on their specific characteristics. The 5th and 7th harmonics receive targeted phase and amplitude adjustment, while other harmonics are handled through general PFC control, creating localized optimization without system-wide complexity.
2Object-generated harmful factors
If specialized compensation for specific factors is implemented, then THD decreases under certain conditions, but adaptability across varying load conditions deteriorates
Solution Approach 1:
The patent implements a universal compensation framework that handles multiple harmonic components (5th, 7th, and other predetermined harmonics) through a single control architecture. This multi-functional approach allows the system to adapt to varying load conditions while maintaining consistent THD reduction performance across different operating points.
Solution Approach 2:
The patent employs dynamic adjustment of harmonic compensation parameters based on real-time operating conditions. The controller continuously monitors and adjusts the phase and amplitude of compensation signals to match changing load characteristics, ensuring consistent performance across light, medium, and heavy load conditions.
3Reliability
If fast input current closed-loop adjustment is used to achieve power factor correction, then power factor improves, but total harmonic distortion increases under light load conditions
Solution Approach 1:
The patent applies preliminary harmonic compensation by injecting counter-phase harmonic signals before they can significantly distort the input current. By anticipating and preemptively compensating for harmonic generation, the system maintains both high power factor and low THD across all load conditions, including light load scenarios where conventional PFC struggles.
Data Source
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AI summary
A power factor correction circuit, a control method and a controller are disclosed. On-time of a main switch of a switching-type regulator is adjusted based on the measured total harmonic distortion, to decrease total harmonic distortion while performing power factor correction, without special compensation for a certain type of factors that affect a total harmonic distortion index, such that the control method is simplified.