DC Carrier Current Communication for Photovoltaic Networks
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Solution Overview
Problem
Existing DC carrier current low-speed communication systems for photovoltaic power supply networks face challenges with reliability and interference resistance, particularly at high temperatures and due to multipath interference from metallic reflectors, and require additional frequency resources and complex installations.
Innovation Solution
A modulated direct current carrier low-speed communication system using a wired bus with transmitters configured to form raw transmission frames, frequency spread using a predetermined spreading factor, and transmitted as a sequence of chips with balanced coding sequences, allowing autonomous start times and error detection, to ensure robustness and simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless communication systems are used in photovoltaic networks, then communication flexibility is improved, but communication reliability deteriorates due to multipath interference from metallic reflectors and masking by photovoltaic panels
Solution Approach 1:
The patent introduces a DC carrier current as an intermediary medium for communication, replacing wireless electromagnetic waves. The communication signals are superimposed on the existing DC power cables, using the power cable as a dual-purpose medium for both power transmission and data communication, thereby eliminating multipath interference issues while maintaining communication flexibility
Solution Approach 2:
The patent replaces the wireless electromagnetic field-based communication system with an electrical current-based communication system. By substituting radio waves with modulated DC carrier currents transmitted through conductive power cables, the system eliminates the harmful effects of multipath interference and masking while achieving more reliable communication
2Reliability
If commercial communication transmitters and receivers with classic modulations are used, then communication capability is achieved, but device complexity and cost increase
Solution Approach 1:
The patent makes the existing DC power cables serve multiple functions: both power transmission and data communication. By superimposing communication signals on the DC carrier, the system eliminates the need for separate communication wiring and complex commercial communication modules, thereby reducing device complexity and cost while maintaining communication capability
Solution Approach 2:
The patent merges the power transmission function and data communication function into a single DC carrier current system. The communication signals are combined with the power transmission current, allowing both functions to be performed through the same physical medium (power cables), thus simplifying the overall system architecture
3Reliability
If commercial communication modules with FSK modulation are used, then communication is enabled, but temperature resistance deteriorates as operating range is limited to 85°C while photovoltaic modules reach 95-100°C
Solution Approach 1:
The patent employs a simplified communication protocol and modulation scheme that can be implemented with basic electronic components rather than expensive commercial modules. This approach uses simpler, more robust components that can withstand higher temperatures, effectively replacing temperature-sensitive commercial modules with temperature-resistant custom-designed components
Solution Approach 2:
The patent changes the communication approach by using DC carrier current modulation instead of FSK modulation in commercial modules. This parameter change allows the system to operate reliably at higher temperatures by using simpler electronic components with wider temperature operating ranges, eliminating the 85°C limitation of commercial modules
4Reliability
If additional wiring is installed for communication, then communication reliability is improved, but installation complexity and cost increase
Solution Approach 1:
The patent makes the existing DC power cables serve multiple functions: both power transmission and data communication. By superimposing communication signals on the DC carrier, the system eliminates the need for separate communication wiring, thereby reducing installation complexity and cost while maintaining communication capability through the existing power infrastructure
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
The system reliably transmits data asynchronously at average frequencies with improved resistance to high temperatures and interference, reducing complexity and cost while maintaining high reliability and adaptability to varying numbers of photovoltaic modules.
Implementation Method 1
modulating and transmitting on the wired bus the chips of the second spread frame into a transmitted communication signal according to a predetermined modulation
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a system for low data-rate communication over a modulated direct carrier current, having one or more communication transmitters (6, 8), a communication receiver (10), and a wire bus (12) forming a shared transmission channel. Each communication transmitter (6, 8) is configured to form a first raw staggered transmission frame according to a second staggered transmission frame, said staggered transmission frames using a set of separate basic chip-encoding sequences. The basic encoding sequences for staggering the symbols used by all the communication transmitters (4, 6) are identical, and the times of the initial transmission of the second staggered frames produced by each transmitter (6, 8) are autonomously and freely determined by each transmitter (6, 8), without taking into account any synchronization signal external to the transmitter (6, 8).