Powered Device Power Transition Circuit
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Solution Overview
Problem
The IEEE 802.3af standard for PoE technology results in communication interruptions during power transitions due to the delay in resuming normal power supply from the PSE, as it takes up to four seconds to detect and classify functioning PDs, leading to an idle mode that disrupts continuous power delivery.
Innovation Solution
A powered device (PD) with a first and second conversion circuit, diodes, a power switch control circuit, and a constant current source is designed to manage power transitions by maintaining a normal power supply mode through a maintain power signal, ensuring continuous operation by drawing at least 10 mA from the PSE when the local power fails, and disabling power transmission to reduce consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PSE detects and classifies PDs during power transition, then power supply reliability is improved, but communication continuity deteriorates due to up to four seconds interruption
Solution Approach 1:
The patent applies preliminary action by pre-classifying the PD during normal operation before power failure occurs. The PSE maintains classification data ready in advance, so when power failure happens and the PD reconnects, the PSE can immediately resume normal power supply mode without performing detection and classification again, thereby eliminating the 4-second communication interruption.
2Loss of energy
If the PSE remains in idle mode during local power supply operation, then power consumption is reduced, but power delivery speed deteriorates when switching to PSE power
Solution Approach 1:
The PSE performs preliminary classification of the PD during normal operation before local power failure occurs. This pre-classification allows the PSE to maintain classification data ready, so when switching to PSE power supply after failure, the resumption is immediate without detection delays, thus improving power delivery speed while the PSE can remain in a low-power state during stable local power operation.
3Stability of the object's composition
If the PSE performs detection and classification every two seconds, then power supply stability is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by completing the detection and classification process during normal operation before power failure occurs. The PSE maintains the classification data ready in advance, eliminating the need for repeated detection and classification cycles after failure. This reduces the control complexity while maintaining power supply stability, as the pre-performed classification ensures immediate resumption without requiring continuous monitoring cycles.
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 ensures uninterrupted communication and reduced power consumption by maintaining the PSE in a normal mode during local power failures, minimizing service interruptions and optimizing power usage.
Implementation Method 1
A first diode is connected between the local power source and a first input of the first conversion circuit, and a second diode is connected between the PSE and a second input of the first conversion circuit
Implementation Method 2
A first conversion circuit is configured for converting a voltage input by a first input into a rated working voltage of the powered device
Data Source
AI summary
An exemplary powered device (PD) connected to a local power source and a power sourcing equipment (PSE) includes a constant current source drawing at least 10 mA direct current from the PSE when the local power source is in operation. The PD includes a first conversion circuit, a first diode, and a second diode. The first conversion circuit comprises a first input and is configured for converting a voltage input to the first input into the rated working voltage of the PD. The positive terminal of the first diode is connected to the local power source and the negative terminal thereof is connected to the first input. The voltage of the local power source is higher than that of the PSE.