PoE PSE Voltage Drop Compensation via PD Load Control
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Solution Overview
Problem
In Power over Ethernet (PoE) systems, a fixed output voltage from Power Sourcing Equipment (PSE) can result in unsatisfactory voltage delivery to Powered Devices (PD) due to excessive line voltage drops across network cables, affecting normal operation and potentially leading to power failures.
Innovation Solution
The PSE determines the line voltage drop across the network cable and sends Ethernet packets to the PD with instructions to reduce load power consumption when the drop exceeds a threshold, thereby managing power control to ensure the required voltage is met, and also monitors network cable temperature to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PSE supplies power at a fixed output voltage, then the power supply system is simple and stable, but the voltage received by PD becomes unsatisfactory due to excessive line voltage drop
Solution Approach 1:
The PSE detects the line voltage drop by measuring impedance and current, then sends Ethernet packets to the PD with instructions to reduce load power consumption when the voltage drop exceeds a threshold. This closed-loop feedback mechanism dynamically adjusts the PD's power consumption to compensate for line losses, ensuring reliable power delivery despite cable losses.
Solution Approach 2:
The system changes the operating parameters of the PD by instructing it to adjust its load power consumption level. When line voltage drop is detected, the PD reduces its power consumption to match the available voltage, thereby resolving the contradiction between fixed output voltage and variable line losses.
2Reliability
If PSE increases output voltage to compensate for line drop, then PD receives sufficient voltage, but network cable temperature increases causing overheating
Solution Approach 1:
The PSE monitors both voltage drop and cable temperature, using feedback control to adjust PD power consumption. When temperature exceeds thresholds, the system reduces power delivery to prevent overheating, balancing voltage requirements with thermal safety.
Solution Approach 2:
The system dynamically adjusts the power delivery level based on real-time conditions. Rather than using a fixed high voltage, the PSE modulates the power output to match actual network conditions, ensuring sufficient voltage delivery while preventing cable overheating through adaptive control.
3Productivity
If PD maintains high load power consumption, then PD operates at full performance, but voltage received becomes insufficient affecting normal working
Solution Approach 1:
The PSE provides feedback to the PD about the actual power delivery conditions. When line voltage drop is detected, the system communicates this to the PD, which then adjusts its performance level to match the available power, ensuring stable operation at reduced but sufficient performance levels.
Solution Approach 2:
The PD adjusts its operating parameters (power consumption level) based on the power delivery conditions. By dynamically changing its load characteristics, the PD can operate reliably within the available voltage budget while maximizing performance under the given constraints.
4Reliability
If PSE monitors and controls power consumption, then power delivery reliability improves, but system complexity increases
Solution Approach 1:
The PSE utilizes existing Ethernet communication infrastructure to convey power control instructions, making the existing data network serve a dual function. This multi-functionality approach adds power management capability without requiring separate dedicated control channels or infrastructure, thereby limiting the increase in system complexity.
Solution Approach 2:
The PD autonomously adjusts its own power consumption based on instructions from the PSE, without requiring complex external control mechanisms. This self-service approach simplifies the overall system architecture by distributing the control intelligence to the endpoint device rather than requiring centralized complex control.
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 ensures the PD operates normally by adjusting power consumption based on voltage drops and temperature, preventing power failures and maintaining network reliability and safety.
Implementation Method 1
determining, by the PSE, impedance of the network cable before supplying power to the PD
Implementation Method 2
determining, by the PSE, network cable temperature according to power consumption of the network cable
Data Source
AI summary
A PoE-based power supply method and PSE. The method includes: after PSE supplies power to a PD, determining, by the PSE, a line voltage drop across a network cable between the PSE and the PD; and when the line voltage drop across the network cable is greater than a line voltage drop threshold, sending, by the PSE, a first Ethernet packet to the PD, so that the PD decreases load of the PD according to instruction information instructing the PD to decrease load power consumption and included in the first Ethernet packet. This ensures that a voltage received by the PD can satisfy a power requirement of the load of the PD, and further ensures that the PD can work normally.