PLC Interface Circuit Using Magnetic Ring Isolation
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Solution Overview
Problem
The direct capacitor coupling method in power line communication for solar power generation systems imposes strict requirements on capacitor selection, leading to increased costs and safety concerns due to high voltage differences and signal attenuation issues.
Innovation Solution
A magnetic ring coupling method is introduced, where power lines connected to capacitors pass through the magnetic ring, and a signal line connects the inverter, reducing the need for multiple capacitors and lowering safety and design complexities by isolating high voltages from the modulation circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct capacitor coupling method is used to transmit PLC signal, then signal transmission can be achieved, but strict requirements on capacitor selection are imposed leading to increased costs and safety concerns
Solution Approach 1:
The patent introduces a magnetic ring as an intermediary component to couple the PLC signal from the power line to the signal line. The magnetic ring acts as a mediator that transfers the high-frequency PLC signal while blocking the direct transmission of high voltage DC, thereby eliminating the need for high-voltage-rated capacitors and reducing component selection complexity
Solution Approach 2:
The patent replaces the direct electrical coupling method (using capacitors) with a magnetic coupling method. By using electromagnetic induction through the magnetic ring, the PLC signal is transferred without direct electrical connection, substituting a mechanical/electrical system with an electromagnetic field-based system that simplifies component requirements
2Reliability
If direct capacitor coupling method is used, then PLC signal can be transmitted, but high voltage difference (up to 1500V) imposes strict safety requirements on capacitor selection
Solution Approach 1:
The magnetic ring serves as an intermediary that isolates the high-voltage power line from the low-voltage signal line. It allows the PLC signal to pass through magnetic coupling while blocking the high-voltage DC from reaching the modulation circuit, thereby eliminating the safety hazard of high voltage impacting sensitive electronics
Solution Approach 2:
The patent replaces direct electrical connection (which exposes the modulation circuit to high voltage) with electromagnetic coupling through the magnetic ring. This substitution creates galvanic isolation, preventing high voltage from directly impacting the modulation circuit while still allowing signal transmission
3Reliability
If direct capacitor coupling method is used, then PLC signal transmission is possible, but signal attenuation becomes excessively severe
Solution Approach 1:
The patent replaces the capacitor-based electrical coupling with magnetic coupling through the magnetic ring. This substitution reduces signal attenuation because the magnetic coupling provides a more efficient path for high-frequency PLC signals, minimizing energy loss and improving signal transmission quality
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 solution reduces the specification requirements for capacitors, improves safety performance, and lowers the overall costs of the solar power generation system by using a single magnetic ring for power line communication, while maintaining effective signal transmission.
Implementation Method 1
the power line connected to either end of the plurality of capacitors passes through the magnetic ring; and the signal line passes through the magnetic ring
Data Source
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AI summary
Embodiments of this application disclose an interface circuit, a string, and a system that are applied to power line communication, to lower device specifications, for example, a safety specification and a capacitance value, and reduce design difficulty. The system includes: an inverter, an optimizer group, a capacitor, a magnetic ring, power lines, and a signal line. An optimizer in the optimizer group is configured to adjust a size of a direct current output by a photovoltaic module connected to the optimizer. Two ends of the signal line passing through the magnetic ring are connected to the inverter. Two ends of a power line passing through the magnetic ring are respectively connected to the capacitor and the optimizer group. An interface circuit including the signal line, the magnetic ring, the power lines, and the capacitor is configured to transmit a power line communication PLC signal. By using the foregoing interface circuit, a high voltage of a direct current output by the optimizer group is prevented from being introduced into the inverter, thereby reducing a specification requirement and design difficulty of a device such as a capacitor.