Power Factor Correction Circuit Switching Frequency Control
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Solution Overview
Problem
Existing power factor correction circuits in power converting modules face efficiency decreases due to increased switching loss and reduced input current when input voltage is low, leading to inefficiencies in power factor correction.
Innovation Solution
A power factor correction circuit that adjusts the switching frequency by using a reference wave with a slope based on a first or second signal, and an error voltage to control the main switching element, limiting the switching frequency when the input voltage is low, thereby maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If boundary conduction mode is used for ease of zero voltage switching implementation, then zero voltage switching is achieved, but switching loss increases and efficiency decreases when input voltage is low
Solution Approach 1:
The patent dynamically switches between two conduction modes (CCM and DCM) based on operating conditions. When input voltage is high, it operates in CCM with continuous inductor current; when input voltage is low, it transitions to DCM with discontinuous inductor current, optimizing efficiency across different voltage ranges while maintaining ZVS capability
Solution Approach 2:
The patent changes the conduction mode parameter based on input voltage levels. By detecting input voltage conditions and switching between CCM and DCM operation, the system adapts its working parameters to minimize switching loss at low voltages while preserving the ease of ZVS implementation
2Power
If switching frequency increases when input voltage is low, then power conversion is maintained, but switching loss increases and efficiency decreases
Solution Approach 1:
The system dynamically adjusts its operation by transitioning from CCM to DCM when input voltage drops. This dynamic mode switching allows the converter to maintain power conversion capability while operating at lower switching frequencies in DCM, thereby reducing switching loss and improving efficiency at low input voltages
3Reliability
If input current average value is increased to correct power factor, then power factor correction is achieved, but switching frequency increases when input voltage is low
Solution Approach 1:
The patent employs dynamic mode switching between CCM and DCM to achieve power factor correction. By transitioning to DCM at low input voltages, the system can increase the average input current for effective power factor correction while operating at reduced switching frequencies, thus avoiding the trade-off between correction effectiveness and switching frequency increase
Data Source
AI summary
There is provided a power factor correction circuit capable of correcting a power factor of a power converting module through increasing an input current by switching a main switching element of a power converting module on the basis of a first reference wave having a slope based on a first signal and an error voltage, in particular, by limiting a switching frequency on the basis of a first reference wave having a slope based on a second signal lower than a first signal and an error voltage when the switching frequency of the main switching element increases because an input voltage of the power converting module is low.