Current Mode Power Line Communication via Transformer
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Solution Overview
Problem
Transmission of communication signals over DC power lines is challenging due to the capacitive nature of loads and sources, which causes low impedance and noise issues, differing from AC power grids, and existing solutions like series inductive filters are costly and inefficient.
Innovation Solution
The use of current transformers, specifically with Rogowski coils, to convert current mode AC signals for communication, combined with capacitors and ferrite filters to manage impedance and noise, allowing effective transmission of AC communications signals over DC power lines by leveraging the capacitive nature of the bus and minimizing signal attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If series inductive filters are used to manage impedance and noise on DC power lines, then noise suppression is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a current transformer as an intermediary device that couples the DC power line to the communication system. This transformer mediates between the capacitive DC bus and the voltage-mode communication signals, enabling signal transmission without requiring complex series inductive filters throughout the entire power line. The transformer handles impedance matching and noise isolation at a localized point.
Solution Approach 2:
The patent changes the fundamental parameter of signal mode from voltage-mode to current-mode transmission. By transmitting communication signals as current variations rather than voltage variations on the DC bus, the system exploits the capacitive nature of DC loads to its advantage, eliminating the need for complex filtering while maintaining signal integrity and reducing noise susceptibility.
2Productivity
If voltage-mode AC signals are transmitted over DC power lines, then communication is enabled, but signal attenuation increases due to low impedance
Solution Approach 1:
The patent fundamentally changes the transmission parameter from voltage-mode to current-mode. By encoding communication signals as current variations on the DC bus, the system leverages the low impedance characteristic of capacitive loads to transmit signals efficiently. The current transformer converts these current-mode signals to voltage-mode for processing, achieving communication without significant signal attenuation.
Solution Approach 2:
The current transformer serves as an intermediary that bridges the gap between current-mode transmission on the DC bus and voltage-mode processing. It converts the current variations carried on the low-impedance DC bus into proportional voltage signals, enabling effective communication while minimizing signal loss that would occur with direct voltage-mode transmission.
3Adaptability or versatility
If DC-DC converters are used on DC bus, then voltage level conversion is achieved, but noise emission increases
Solution Approach 1:
The current transformer acts as an intermediary that isolates the communication signals from the noisy DC-DC converter circuitry. By coupling the DC bus through the transformer rather than directly connecting communication devices to the bus, the transformer provides galvanic isolation and shields the communication signals from high-frequency noise generated by power conversion operations.
Solution Approach 2:
The patent extracts the communication signal transmission function from the noisy DC-DC converter environment. By using the current transformer to couple communication signals onto the DC bus at a point away from the converter, and by transmitting signals as current variations rather than voltages, the system separates the communication function from the noise-generating power conversion function.
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 enables reliable and cost-effective transmission of AC communications signals over DC power lines with minimal signal loss, avoiding the need for large, expensive inductive filters and maintaining low impedance, thus supporting applications like solar panel monitoring and direct current power distribution systems.
Implementation Method 1
A current transformer is coupled to the power bus adjacent the solar panel
Implementation Method 2
A capacitor, coupled to the power bus, is connected in parallel with the solar panel
Implementation Method 3
the current transformer includes the high current wire line as a primary winding and a Rogowski coil as a secondary winding
Data Source
AI summary
An apparatus and method includes a solar panel. A power bus is coupled to the solar panel, and supports transmission of AC communication signals. The power bus includes a high current power wire. A current transformer is coupled to the power bus adjacent the solar panel. A capacitor, coupled to the power bus, is connected in parallel with the solar panel, and connected between the solar panel and the current transformer.