Switching Power Supply Capacitor Failure Detection Circuit
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Solution Overview
Problem
Existing switching power supplies using electrolytic capacitors for filtering face reliability issues due to low and high-temperature service life limitations, leading to premature failures and increased costs from redundant designs and inability to forecast capacitor failures.
Innovation Solution
A direct filtering type switching power supply with an indicating circuit comprising a light emitting unit and a first inductor, where the current direction of the direct current input through the inductor is opposite to the conducting direction of the light emitting unit, allowing for early indication of electrolytic capacitor failure before complete failure occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If electrolytic capacitors are used for filtering in switching power supplies, then the power supply can operate with simple circuit topology, but the capacitors have limited service life at low and high temperatures leading to premature failures
Solution Approach 1:
The patent applies preliminary action by adding an indicating circuit that detects capacitor health status before complete failure occurs. The circuit monitors the capacitor's equivalent series resistance (ESR) and provides early warning through a light emitting diode when the capacitor approaches failure, allowing proactive replacement before the power supply fails completely.
Solution Approach 2:
The patent implements feedback by creating a monitoring system that continuously checks the capacitor's condition and provides visual feedback through the LED indicator. This feedback mechanism allows the system to alert users about capacitor degradation, enabling timely maintenance and improving overall system reliability.
2Device complexity
If electrolytic capacitors are used for filtering, then the power supply structure remains simple, but the inability to forecast capacitor failures leads to increased costs from redundant designs
Solution Approach 1:
The patent uses an intermediary approach by introducing a monitoring circuit as a mediator between the capacitor and the user. This intermediary circuit measures the capacitor's ESR and translates the invisible degradation process into visible LED signals, providing information about capacitor health without adding complex monitoring systems.
Solution Approach 2:
The patent applies self-service by enabling the power supply to autonomously monitor and report its own health status. The indicating circuit automatically detects capacitor degradation and provides warnings without external intervention, allowing the system to inform users about its own condition and reduce the need for redundant design measures.
3Ease of manufacture
If no indicating circuit is added to monitor capacitor health, then the power supply remains cost-effective, but premature failures occur without warning leading to increased losses
Solution Approach 1:
The patent employs this principle by using inexpensive components (resistors, LEDs) for the indicating circuit that can easily replace the expensive consequence of power supply failure. The low-cost monitoring circuit provides valuable failure warning capability, preventing much larger losses from unexpected power supply failures.
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
The solution provides a low-cost, efficient, and reliable method to predict electrolytic capacitor failure, reducing the need for redundant designs and minimizing losses by emitting a light or isolated signal when the capacitor is nearing failure, thus enabling proactive maintenance.
Implementation Method 1
the indicating circuit is formed by connecting a light emitting unit having unidirectional conductivity with a first inductor in parallel
Data Source
AI summary
A direct filtering type switching power supply is provided, for an occasion including pulsating direct current, including a filter circuit, a main power stage and an indicating circuit. A direct current input is connected to the filter circuit through the indicating circuit. The filter circuit and the main power stage are connected in parallel. The indicating circuit is formed by connecting a light emitting unit with an inductor in parallel, and make sure that the direction of the direct current input passing through the inductor is opposite to the conducting direction of the light emitting unit. The filter circuit at least includes an electrolytic capacitor. When the electrolytic capacitor is normal, an excitation current of a switching transistor in the main power stage basically does not appear in the inductor, and an LED in the light emitting unit does not emit light. When the Equivalent Series Resistance of the electrolytic capacitor rises greatly, the excitation current of the switching transistor appears in the inductor. Furthermore, when the switching transistor is switched off, the excitation current flowing through the inductor, which cannot be changed abruptly, freewheels through the LED, and drives the LED to emit light, so as to notify a user or a circuit that the electrolytic capacitor may have the risk of complete failure. The LED may also be a light emitter of a photocoupler. The switching power supply is low in cost, has unchanged efficiency and is easy to implement.