Power Factor Correction Circuit Over-Voltage Detection
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Solution Overview
Problem
Existing power factor correction circuits face issues with slow control response leading to over-voltage, which can damage components and increase production costs due to the need for additional parts to prevent over-voltage, especially when using resistor elements for voltage division.
Innovation Solution
A power factor correction circuit that detects over-voltage without using resistor elements, employing an inductor, power switch, auxiliary inductor, and a power factor correction controller with an over-voltage protector that generates input peak voltage and duty voltage to determine over-voltage conditions based on clamping current and control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor element is used to divide the output voltage for feedback, then the feedback voltage can be adjusted within a suitable voltage range, but power consumption increases and production costs increase due to the need for very large resistors and additional parts
Solution Approach 1:
The patent extracts the over-voltage detection function from the traditional resistor-based voltage division circuit. By using a capacitor to directly detect output voltage and compare it with a reference voltage, the system eliminates the need for large resistor elements, thereby reducing power consumption while maintaining over-voltage protection capability
Solution Approach 2:
The capacitor in the patent serves multiple functions: it acts as a filtering capacitor for the output voltage, simultaneously functions as a detection element for over-voltage conditions, and provides a voltage signal for comparison with the reference voltage. This multi-functionality eliminates the need for separate resistor-based voltage division circuits
2Reliability
If additional resistor elements are connected to the output terminal to prevent over-voltage, then over-voltage protection is improved, but production costs increase due to increase in power consumption and expense of additional parts
Solution Approach 1:
The patent removes the need for additional resistor elements by extracting the over-voltage detection function and implementing it through a capacitor-based voltage detection circuit. The control circuit directly monitors the capacitor voltage and compares it with a reference voltage to detect over-voltage conditions, eliminating the need for extra protective components
Solution Approach 2:
The capacitor naturally charges to the output voltage and serves as a self-contained detection element. When the output voltage exceeds the reference voltage, the capacitor voltage automatically reflects this condition, and the control circuit detects it without requiring additional protective parts or complex detection mechanisms
3Device complexity
If the control response of the power factor correction control circuit is slow, then the circuit is simpler, but the output voltage becomes over-voltage which can damage components
Solution Approach 1:
The patent implements preliminary over-voltage detection by continuously monitoring the capacitor voltage against a pre-set reference voltage. This allows the control circuit to detect potential over-voltage conditions before they cause damage, enabling preventive action while maintaining a relatively simple circuit structure
Solution Approach 2:
The patent establishes a feedback mechanism where the control circuit monitors the output voltage through the capacitor and reference voltage comparison, and adjusts its operation based on the detected voltage level. This feedback loop enables the simple control circuit to respond to voltage changes and prevent over-voltage damage
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces power consumption and eliminates the need for additional parts, effectively preventing over-voltage without direct output voltage detection, thereby reducing production costs and component damage.
Implementation Method 1
an auxiliary inductor (L2), which generates an auxiliary voltage according to an input voltage
Implementation Method 2
a clamping unit (25), which maintains a zero current detection voltage at a predetermined clamping voltage by using a clamping current
Implementation Method 3
generates an input peak voltage corresponding to the peak of the input voltage by using a clamping current for maintaining a zero current detection voltage
Data Source
AI summary
The present invention relates to a power factor correction circuit and a driving method thereof.The power factor correction circuit includes: an inductor for receiving an input voltage and supplying output power; a power switch connected to the inductor to control an inductor current flowing through the inductor; an auxiliary conductor coupled to the inductor with a predetermined turn ratio; and a power factor correction controller that controls the output power by controlling the switching operation of the power switch and determines whether or not the output voltage of the output power is an over-voltage. The power factor correction controller generates an input peak voltage corresponding to the peak of the input voltage by using a clamping current for maintaining an auxiliary voltage, which is the both-end voltage of the auxiliary inductor, at a predetermined clamping voltage during the turn-on period of the power switch so as to prevent the auxiliary voltage from becoming a negative voltage, generates a duty voltage corresponding to the duty of the power switch, and determines whether or not the output voltage is an over-voltage according to a result of comparison between the input peak voltage and the duty voltage.