Power Sourcing Equipment Effective Resistance Determination
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Solution Overview
Problem
Current Ethernet-based power over local area networks lack a method to accurately determine the effective resistance between Power Sourcing Equipment (PSE) and Powered Devices (PD), leading to inefficient power allocation and potential waste due to reliance on worst-case scenarios.
Innovation Solution
A method involving the impression of disparate current flow levels between the PSE and PD, measuring voltages at both ends, and calculating effective resistance to accurately allocate power based on actual cable conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is allocated based on worst-case effective resistance, then power allocation is conservative and reliable, but power is wasted due to over-allocation
Solution Approach 1:
The patent replaces the manual or static worst-case resistance assumption with an automated electrical measurement system. The PSE actively measures actual cable resistance by applying test voltages and measuring currents during the classification phase, substituting conservative estimation with precise empirical data to optimize power allocation.
Solution Approach 2:
The patent changes the parameter used for power allocation from a fixed worst-case resistance value to a dynamically determined actual resistance value. By measuring and using the real cable resistance characteristics, the system adjusts power allocation parameters to match actual conditions, reducing waste while maintaining reliability.
2Measurement precision
If multiple current levels are impressed to measure voltage for resistance determination, then effective resistance is accurately determined, but device complexity increases
Solution Approach 1:
The patent makes the existing classification circuitry multi-functional by using it both for device classification and for measuring cable resistance characteristics. The same voltage sources and current measurement capabilities used for power classification are repurposed to determine effective resistance, avoiding the need for separate dedicated measurement hardware.
Solution Approach 2:
The patent performs resistance measurement during the initial classification phase before full power operation begins. By conducting voltage applications and current measurements during this preliminary setup stage, the system determines cable characteristics without requiring additional measurement stages or complex ongoing monitoring infrastructure.
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 allows for precise power allocation, reducing waste by accounting for actual resistance, enabling support of PDs with lower power requirements and optimizing overall network power management.
Implementation Method 1
determining the effective resistance between the PSE and the PD, the effective resistance being primarily a function of cable quality and cable length
Data Source
AI summary
A method of determining an effective resistance between a power sourcing equipment and a powered device, the powered device exhibiting an interface and an operational circuitry, the method comprising: prior to connecting power to the operational circuitry of the powered device, impressing two disparate current flow levels (I1, I2) between the power sourcing equipment and the powered device; measuring the voltage at the powered device interface (VPD1, VPD2) responsive to each of the impressed disparate current levels; measuring the voltage at the power sourcing equipment (VPSE1, VPSE2) responsive to each of the impressed disparate current levels; and determining the effective resistance between the power sourcing equipment and the powered device responsive to the VPD1, VPD2, VPSE1, VPSE2, I1 and 12.