PFC Bus Bar Voltage Equalization via Fan Speed Control
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Solution Overview
Problem
Power Factor Correction (PFC) circuits face challenges in maintaining balanced bus bar voltages during uncontrolled rectification or lightly loaded conditions, where the biased voltage loop's ability to adjust and equalize voltages is weakened, leading to unbalanced voltages.
Innovation Solution
A method and apparatus that calculate the voltage difference between positive and negative bus bars and increase the rotation speed of a fan within the PFC circuit until the voltages are equalized, enhancing the biased voltage loop's ability to adjust and balance the bus bar voltages without adding hardware or altering the original circuit structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a biased voltage loop is adopted to control bus bar voltage equalization, then the voltages of positive and negative bus bars can be equalized under normal operating conditions, but the equalization ability is weakened when the PFC circuit operates in uncontrolled rectification or lightly loaded conditions
Solution Approach 1:
The patent applies dynamics by making the fan rotation speed adjustable rather than fixed. The control module dynamically changes the fan speed based on real-time voltage difference detection, allowing the system to adapt to different operating conditions (uncontrolled rectification, light load, normal operation) and maintain effective voltage equalization across all scenarios
Solution Approach 2:
The patent implements feedback control by continuously detecting the voltage difference between positive and negative bus bars and using this information to adjust the fan rotation speed. The detection module monitors voltage equality status and feeds this information back to the control module, which then adjusts the fan speed accordingly to maintain voltage balance
2Reliability
If the fan rotation speed is increased to improve output power and PWM wave transmission, then the biased voltage loop's ability to equalize voltages is improved, but additional hardware or structural changes would be required
Solution Approach 1:
The patent applies universality by making the fan serve multiple functions: it provides both cooling for the PFC circuit and acts as a variable load to influence output power and PWM wave transmission. By controlling fan speed, the system simultaneously achieves thermal management and voltage equalization without requiring separate dedicated components for each function
Solution Approach 2:
The patent implements self-service by using the fan, which is already an integral part of the PFC circuit structure, to achieve voltage equalization. The system leverages the existing fan component and its control mechanism to perform the additional function of voltage balance adjustment, eliminating the need for separate equalization hardware
Data Source
AI summary
An automatic equalization method and apparatus for bus bar voltages of a Power Factor Correction (PFC) circuit. The method includes calculating a difference in voltages of a positive bus bar and a negative bus bar, and increasing the rotation speed of a fan in the PFC circuit according to the difference in voltages of the positive bus bar and the negative bus bar until the voltages of the positive and negative bus bars are equalized. The apparatus includes a voltage difference module configured to calculate a difference in voltages of a positive bus bar and a negative bus bar, and a rotation speed control module configured to increase a rotation speed of a fan in the PFC circuit according to the difference in voltages of the positive bus bar and the negative bus bar, until the voltages of the positive and negative bus bars are equalized.