Method for realizing dc/ac power conversion and power line carrier communication by sharing inverter circuit

Abstract

The invention discloses a method for achieving DC / AC power conversion and power line carrier communication by sharing an inverter circuit. According to the method, ripple signals are superposed at anoutput port by using components of a grid-connected inverter, and all devices connected to the output port in parallel can detect the signals, so that data can be sent without adding any device through adoption of the method, and a certain signal-to-noise ratio is ensured. Compared with the prior art, the self structure of the grid-connected inverter is directly utilized, extra data sending hardware is not needed, the cost is saved, the data transmission distance is longer, the influence of electromagnetic interference of the inverter is not likely to happen, and the safety and the reliabilityare better; and moreover, when a certain inverter works abnormally, other devices cannot be damaged through a communication line. In addition, the communication ripple amplitude can be adjusted, andthe communication quality can be obviously improved.

Description

technical field [0001] The invention belongs to the technical field of grid-connected inverters, and in particular relates to a method for realizing DC / AC power conversion and power line carrier communication by sharing an inverter circuit. Background technique [0002] The grid-connected inverter is a special kind of inverter, which converts direct current into alternating current and feeds it back to the mains; the grid-connected inverter has a wide range of applications in life and production, among which the photovoltaic grid-connected inverter is the Typical representatives, photovoltaic grid-connected inverters are divided into centralized inverters, string inverters and micro inverters in terms of implementation. In a grid-connected inverter system, it is usually necessary to monitor the parameters of each inverter, that is, to exchange data with each inverter through the host computer software, so the inverter needs to have a reliable communication function. [0003...

AI Technical Summary

Problems solved by technology

[0003] Currently commonly used data communication methods include: The first method is to use wireless communication, such as Bluetooth, but if Bluetooth is installed in the inverter, it will cause serious data interference, because the inverter is a power transmission module, and the It contains a switch tube, which will cause serious electromagnetic interference when the switch tube operates. If Bluetooth is placed close to the inverter, it will affect the quality of communication. The ideal situation is that Bluetooth and the inverter can reserve a distance of more than 1m, but At this time, long wires need to be drawn from the inverter, which increases the cost and floor space; at the same time, Bluetooth is sensitive to distance. If the two communication devices are far apart or there is a wall or building in the middle, the communication will be seriously affected. signal strength

[0004] The second method uses wired communication. The common way is to use the communication method combining RS-485 communication line and network cable, such as figure 1 As shown, the reason for using the 485 bus is that it transmits data through differential signals and has a strong ability to resist common-mode interference; similarly, because of the electromagnetic interference of the inverter, the RS-485 communication line uses a twisted-pair shielded cable, and the network cable uses Cat5e twisted-pair shielded network cable, this solution has higher cost due to higher requirements on cable quality

Taking a micro-inverter as an example, 20 micro-inverters need to be equipped with 20 wireless communication modules or 20 RS-485 communication lines for communication, and at the same time, it is necessary to reserve a part of the space in the micro-inverter for these communication modules The interface is not the best choice in terms of cost and floor space

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