Methods of Implementing DC PLC Protocols

DC PLC communication mainly controls and monitors the condition of solar panels and energy storage systems. Additionally, DC PLC technologies are applied in industrial settings to supply power to electric motors and control them using a single pair of wires. All these applications suggest that the units responsible for communication over the power line are typically integrated into the corresponding devices (solar panel controllers, machines, and robots). Therefore, many automation system developers must understand how PLC protocols over DC power lines are implemented.

G3-PLC

The G3-PLC protocol is maintained by the international organization G3-Alliance.

Chipsets for this protocol generally comprise two microchips: an analog device for interfacing with the transmission line and a specialized microcontroller (SoC). In addition to signal processing, the microcontroller also handles encryption of the data transmitted over the line. The chipset may include a third chip responsible for converting the G3-PLC signal to one of the wireless protocols and back. Typically, this is the G3-Hybrid protocol designed for wireless networks to work alongside PLC. This protocol uses the 868 and 915 MHz frequency bands (which are not allowed for use in all countries).

The chipsets and their firmware must be certified by the G3-Alliance to bear the G3-PLC label. However, such certification does not negate the need to certify G3-PLC solutions with national communications authorities if required by local regulations.

At least three manufacturers of G3-PLC chipsets are known: Maxim Integrated (a division of the US-based Analog Devices), STMicroelectronics (a European company headquartered in the Netherlands), and Vertexcom Technologies (China).

PLC-Lite

The implementation of this protocol is governed by TI's internal documents. The TMS320F28035 universal signal processor is used for signal processing. In addition, the receiver and transmitter must include the AFE031 line interface chip. The chipset also includes execution devices LM34910 and TPS62170.

IEEE 2847-2021

At the time of writing, a South Korean startup was producing devices supporting IEEE 2847-2021 (HPDS-PLC); the protocol is used in an LED lighting controller and a servo drive. Information about the components used for their development is not publicly available.

Data Transmission from Vehicle Batteries Sensors

A new technology that optimizes electric vehicle charging based on the battery's parameters and its wear level. Wireless sensors are installed on the battery. The wires inside the vehicle through which the charging current flows act as antennas. The signal passes through the electric vehicle charging connector. It continues to propagate along the charging cable as a guided medium. This solves the problem caused by the inability of radio waves to pass through the vehicle's metal body. A transceiver is connected to the cable at the charging station.

This solution uses one of the wireless protocols from the IEEE 802.15.4 family. The most widespread and cost-effective in this family is the Zigbee protocol. Therefore, it makes sense to use a chipset specifically for this protocol. Zigbee uses the 2.4 GHz band, and the frequency data transmission occurs along the charging station's cable. It should be noted that this solution is only possible for DC charging because, in this mode, the wires from the charging connector go directly to the battery.

Is software implementation of PLC algorithms possible?

For G3-PLC, using a general-purpose processor instead of a specialized microcontroller would require more chips than just two. Large production volumes and significant market competition produce relatively low prices for G3-PLC chipsets. These chips are manufactured across different regions—America, Europe, and Asia—ensuring a diversified supply. Therefore, developing a custom G3-PLC solution using general-purpose chips is not economically viable.

In PLC-Lite, a different company's signal processor can be used instead of TI's. However, new firmware would need to be written for it, which is quite costly. The TMS320F28035 is well protected from reverse engineering, so third parties cannot read the firmware stored in its memory.

No specialized chips are being produced yet for the IEEE 2847-2021 protocol, so its signal-processing algorithms must be implemented through the software on general-purpose microcontrollers.

The Zigbee protocol is implemented with a single chip that includes a microcontroller and a transceiver operating in the 2.4 GHz band. Using a general-purpose microcontroller would require a separate radio module, and interfacing these two units would be a highly complex task.

In conclusion, specialized chipsets are more cost-effective for PLC systems (except those using the IEEE 2847-2021 protocol).