PFC Power Supply Control for Capacitor Fault Resonance Prevention
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Solution Overview
Problem
Existing display devices face reliability issues due to capacitor abnormalities, which cause resonance with EMI filters, leading to heat generation and potential damage.
Innovation Solution
A power supply device that controls the switch based on a detection signal from an inductor sensor to identify capacitor abnormalities, preventing resonance by adjusting switching behavior accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switch operates periodically to charge the capacitor, then power factor compensation is achieved, but capacitor abnormality causes resonance with EMI filter leading to heat generation
Solution Approach 1:
The control circuit continuously monitors the detection signal from the sensor to detect capacitor abnormalities before they cause resonance and overheating. By performing preliminary detection and taking preventive action (stopping switch operation), the system avoids the harmful effects of capacitor failure while maintaining normal periodic operation when the capacitor is healthy.
Solution Approach 2:
The system uses a sensor to detect current flowing in the inductor and provides feedback to the control circuit. The control circuit analyzes this detection signal to determine capacitor health status and adjusts switch operation accordingly, creating a closed-loop feedback system that prevents resonance and EMI filter overheating based on real-time capacitor condition.
2Measurement precision
If a separate sensor is added to detect capacitor abnormality, then detection accuracy is improved, but circuit complexity and cost increase
Solution Approach 1:
The sensor originally designed for current detection in the inductor is made multi-functional by using its detection signal for both normal switch control and capacitor abnormality detection. The control circuit processes the same detection signal to identify resonance conditions, eliminating the need for separate detection sensors and reducing overall system complexity while maintaining detection accuracy.
Solution Approach 2:
The patent combines the capacitor abnormality detection function with the existing current sensing mechanism. By merging the detection purposes (current measurement and capacitor health monitoring) into a single sensor and control circuit, the system achieves accurate capacitor status detection without adding separate sensing components, thereby reducing circuit complexity.
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 approach enhances product reliability by accurately detecting capacitor issues and preventing EMI filter heating, thereby reducing the risk of damage.
Implementation Method 1
a sensor that detects current flowing in the inductor
Implementation Method 2
The PFC circuit is provided with a capacitor and a switch used for power factor compensation
Implementation Method 3
If the changed operating frequency resonates with the cut-off frequency of the EMI filter, the EMI filter is heated
Data Source
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AI summary
A power supply device includes an EMI filter, a rectifier for rectifying an AC voltage passing through the EMI filter, a power factor compensation unit for power factor-compensating the rectified voltage and outputting a DC voltage, and a control circuit for controlling the power factor compensation unit. The power factor compensation unit includes a capacitor connected to the output terminal of the rectifier unit, an inductor connected in parallel with the capacitor, and a switch connected in parallel with the inductor. The control circuit acquires whether the capacitor is abnormal based on a detection signal detected from the inductor, and may control the switching of the switch differently depending on whether the capacitor is abnormal.