PLC Interface Circuit Using Magnetic Ring Isolation
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Solution Overview
Problem
The direct capacitor coupling manner in power line communication for solar power generation systems imposes strict requirements on capacitor selection and increases design complexity and costs due to high voltage differences and signal attenuation, posing safety and efficiency challenges.
Innovation Solution
A magnetic ring coupling method is introduced to transmit PLC signals, bypassing high voltages from the optimizer to the inverter, reducing the need for specific capacitor designs and improving safety performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct capacitor coupling is used to transmit PLC signals, then signal transmission is achieved, but strict requirements on capacitor selection increase design complexity and costs
Solution Approach 1:
The patent introduces a common mode choke as an intermediary component between the power line and the modulation circuit. This choke acts as a mediator that blocks high voltage transients from reaching the modulation circuit while allowing PLC signals to pass through, thereby reducing capacitor requirements and simplifying design without compromising signal transmission reliability
Solution Approach 2:
The patent replaces the traditional capacitor-based high voltage blocking mechanism with a magnetic field-based common mode choke. This substitution uses electromagnetic principles instead of relying on capacitor voltage ratings, thereby reducing design complexity and cost while maintaining effective isolation
2Reliability
If direct capacitor coupling is used, then PLC signal transmission is enabled, but high voltage differences pose safety risks to the modulation circuit
Solution Approach 1:
The common mode choke serves as a protective intermediary that isolates the modulation circuit from high voltage transients generated on the power line during capacitor discharge. This mediator allows normal PLC signal transmission while blocking harmful high voltage spikes, thereby ensuring both communication reliability and circuit safety
Solution Approach 2:
The patent implements protective measures in advance by placing the common mode choke before the modulation circuit. This preemptive protection cushions the modulation circuit against potential high voltage damage from capacitor discharge, preventing safety issues before they occur
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 simplifies capacitor requirements, reduces design complexity, and enhances safety by isolating high voltages from the inverter, while also lowering overall system costs.
Implementation Method 1
The power line connected to either end of the at least one capacitor 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.