Power Line Communication Choke Circuit Design
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Solution Overview
Problem
Existing devices are ineffective in reducing common mode current levels in power line communications systems, as they are not suitable for the working voltages and attenuations required, and existing common mode chokes are not designed to handle differential mode effectively, leading to electromagnetic interference and inefficiencies.
Innovation Solution
A process involving a common mode choke circuit with braided signal cables mounted around a toroidal magnetic core is used to minimize differential mode inductance, allowing the common mode choke to be located internally or externally to the communications equipment, particularly at the injection point into the mains network, increasing common mode loop impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If existing common mode chokes are used to reduce common mode current, then common mode attenuation is achieved, but differential mode performance deteriorates and electromagnetic interference increases
Solution Approach 1:
The patent applies different structural characteristics to different parts of the choke circuit. The braided cable configuration provides high common mode attenuation while the toroidal core geometry minimizes differential mode inductance. This local optimization of structural properties allows the device to selectively attenuate common mode currents while preserving differential mode signal integrity.
Solution Approach 2:
The patent employs an asymmetric magnetic core structure (toroidal shape) combined with symmetric braided cable arrangement. This asymmetric core design creates a magnetic path that preferentially couples common mode currents while presenting minimal inductance to differential mode signals, thereby achieving selective common mode rejection without affecting differential mode performance.
2Object-generated harmful factors
If common mode current is reduced using existing devices, then electromagnetic interference decreases, but injected power must be reduced which worsens coverage and efficiency
Solution Approach 1:
The patent extracts and targets only the common mode current component for attenuation while leaving the differential mode power transmission unaffected. By using the braided cable configuration around a toroidal core, the device selectively couples with common mode currents and dissipates them, while the differential mode signals pass through with minimal loss, thereby reducing EMI without sacrificing injected power or coverage.
3Object-generated harmful factors
If conventional common mode chokes are used, then common mode attenuation is provided, but device complexity increases and they are not suitable for power line communications working voltages
Solution Approach 1:
The patent designs a choke circuit that serves multiple functions simultaneously: the braided cable provides both mechanical strength and electromagnetic coupling, the toroidal core provides magnetic flux confinement and minimizes leakage inductance, and the overall structure handles both the required working voltages and common mode attenuation in a single integrated component, reducing overall device complexity.
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 effectively reduces common mode signal levels without decreasing injected power, thereby maintaining communication system efficiency and coverage, as it specifically targets common mode emissions in power line communications equipment.
Implementation Method 1
braided signal cables belonging to the common mode choke circuit mounted around a toroidal magnetic core
Implementation Method 2
increasing the impedance of the common mode loop
Implementation Method 3
common mode choke is described as being that device capable of attenuating or reducing the level of the common mode current
Data Source
AI summary
A method including receiving power, from a power line, at a device configured to communicate via the power line. The power from the power line is received at the device via a power cord of the device being connected, via a connector, to a power outlet from which the power of the power line is supplied. The connector is coupled to a first end of the power cord. The device is coupled to a second end of the power cord. The method further includes supplying a signal generated by the device to a choke located on the power cord. The choke is located closer to the first end of the power cord than to the second end of the power cord. The method further includes transmitting the signal from the choke to the power line for communication via the power line.