One-Pair PoE Automotive Wiring via Chassis Return
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Solution Overview
Problem
In automotive networks, the use of Power over Ethernet (PoE) with a 12V battery source requires higher current levels, leading to increased power losses and voltage drops in cabling due to the lower voltage source, which complicates the implementation and increases the weight of wiring harnesses.
Innovation Solution
Implementing a one-pair PoE system where the forward path current is split between two conductors of a single twisted wire pair, with the return path current carried by the chassis of the automotive vehicle, reducing power losses and voltage drops by utilizing transformers or inductors for coupling and DC blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If Power over Ethernet is implemented with a 12V battery source in automotive networks, then power delivery is achieved, but higher current levels cause increased power losses and voltage drops in cabling
Solution Approach 1:
The patent segments the return current path from the forward current path. The forward current travels through the twisted wire pair conductors to the powered device, while the return current travels through the vehicle chassis ground. This segmentation allows the high current return path to use the low-resistance chassis rather than the high-resistance cabling, significantly reducing I²R power losses in the Ethernet cable.
2Power
If Power over Ethernet is implemented with a 12V battery source in automotive networks, then power delivery is achieved, but higher current levels cause increased voltage drops in cabling
Solution Approach 1:
The patent segments the return current path from the forward current path. The forward current travels through the twisted wire pair conductors to the powered device, while the return current travels through the vehicle chassis ground. This segmentation allows the high current return path to use the low-resistance chassis rather than the high-resistance Ethernet cable, significantly reducing voltage drops in the cabling.
Solution Approach 2:
The vehicle chassis acts as an intermediary conductor for the return current path. Instead of using the Ethernet cable for both forward and return currents, the chassis serves as a low-resistance intermediary that carries the return current, thereby maintaining voltage levels and reducing voltage drops in the powered device.
3Power
If conventional two-pair PoE cabling is used in automotive applications, then power delivery is achieved, but the weight of wiring harnesses increases
Solution Approach 1:
The patent merges the PoE power delivery function with the existing single twisted wire pair data communication infrastructure. By using one pair for forward current and the vehicle chassis for return current, the system eliminates the need for separate power and data wiring, reducing the overall weight of the wiring harness while maintaining both data and power delivery capabilities.
Solution Approach 2:
The vehicle chassis serves multiple functions: it acts as the return current path for PoE power delivery, provides electrical grounding, and serves as the structural framework of the vehicle. This multi-functionality eliminates the need for dedicated return conductors, reducing wiring harness weight while maintaining electrical safety and power delivery.
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 reduces power losses and voltage drops by half, simplifying wiring and reducing the weight of the wiring harness, while maintaining effective power delivery for automotive network devices.
Implementation Method 1
the power sourcing equipment is connected to the single conductor pair via a transformer. In another embodiment, the power sourcing equipment is connected to the single conductor pair via an inductor.
Implementation Method 2
utilizing transformers or inductors for coupling and DC blocking
Data Source
AI summary
System, method and apparatus for one-pair power over Ethernet in an automotive application. In one embodiment, a power sourcing equipment transmits a forward path current to a powered device via a single conductor pair and receives a return path current from the powered device via a chassis of an automotive vehicle.