To achieve the goal of “carbon peaking and carbon neutrality”, energy is the main battlefield, and the solar technology industry is a key area to help my country achieve the “dual carbon” development goal. According to relevant reports, if my country achieves carbon neutrality in 2060, nuclear energy will be more than 5 times that of today, wind energy will be more than 12 times that of today, and solar energy will be more than 70 times that of today! Due to the ever-increasing power density in solar inverters and the need for energy storage balancing, the new generation of solar power requires extensive monitoring of all elements of the solar system.
In addition to following the trend towards smaller and lighter electrical systems, next-generation solar systems must be designed with market requirements in mind, especially to meet increasingly stringent Electromagnetic Compatibility (EMC) specifications. As a result, a compact solution that can meet both safety and EMC requirements is a key strategy for solar system designers. ADI’s isolated RS-485 transceiver, the ADM2867E, has low EMI and can meet EMC compliance requirements with minimal board rework and budget overruns. Compared to the previous generation, this transceiver features a simplified PCB layout and a small SOIC form factor, allowing more functionality to be integrated in applications where space is limited.
Why use RS-485 with isolation?
RS-485 is a multidrop communication network defined by the TIA-485-A/EIA-485-A standard specifying up to 32 drivers and 32 receivers on a single (2-wire) bus, modern transceivers have been improved to allow 256 nodes are supported on the same bus. The differential signaling scheme and wide common-mode tolerance provide excellent noise immunity for high-speed communications over long distances and harsh environments. For solar photovoltaic applications, the inherent noise immunity of RS-485 communication makes it useful. For the controllers of solar Inverter installations, where both DC/DC controllers and DC/AC controllers are used, communication between the controllers is necessary to ensure the efficient operation of the entire system. However, the DC/DC controller is usually electrically isolated from the DC/AC controller, or at least there is a high probability of a large common-mode Voltage between the two grounded systems. Therefore, the communication between the two processors must be electrically isolated. ADI’s iCoupler isolated RS-485 is a robust drop-in solution with proven EMC robustness to reduce field failures.
In addition, the enhanced EMC robustness reduces the design and testing time of interface circuits, thereby accelerating time-to-market for solar PV networks. ADI’s iCoupler family of digital isolation products has been tested and certified by multiple regulatory agencies, including UL, CSA, VDE, TüV, CQC, ATEX, and IECEx, where testing has demonstrated that the product meets the required level of safety, making the product Unaffected by high voltage transients and surges that can occur in solar PV environments with harsh electrical conditions.
How to meet EMC compliance requirements?
When designing an EMC communication interface, circuit designers are often faced with iterative cycles of design and test. Circuit design must comply with system-level EMC standards and customer requirements. EMC’s requirements are like being a good neighbor – not making too much noise and being able to tolerate the noise of neighbors. EMC is divided into two aspects; immunity and emission. Emissions can be further divided into conducted and radiated emissions, while immunity can be divided into conducted immunity, radiated immunity, transient immunity and fault tolerance. Once the system design is complete, EMC problems can be very difficult to solve because as the design progresses, fewer and fewer techniques are available to solve EMC problems. Therefore, EMC design must be considered from the beginning of the project to minimize the time spent on board iterations, while also reducing design time and project costs.
ADI’s iCoupler isolated RS-485 transceiver, the ADM2867E, integrates isolation robustness and EMC protection to significantly save printed circuit board (PCB) space for solar PV communication port interfaces. The device integrates ADI’s low EMI IsoPower technology and uses an isolated DC-DC converter, so there is no need to design an external power supply. The integration of the DC-DC converter allows the integration of an extremely compact isolated RS-485 board in these space-constrained applications, improving EMI and simplifying compliant designs for applications critical to maintaining low manufacturing costs. development, including double-layer circuit boards.
For higher voltage applications, such as solar string inverters, isolation is required for voltages well above RMS. The ADM2867E can provide lifetime isolation for devices with system voltages higher than 1500V DC. The integrated protection device provides Class 4 insulation protection against system-level ESD events in accordance with IEC standards, eliminating the need for external protection devices and providing smart cable inversion capabilities. Cable polarity can be calibrated remotely, solving wiring problems without returning to the installation site.
As IsoPower technology continues to advance, the ADM2867E minimizes electromagnetic emissions, allowing system designers to easily meet stringent Class B standards. The ADM2867E tested on a standard double-layer PCB under load conditions showed that the headroom met the EN 55032 Class B limit requirements without the need for complex EMI suppression techniques such as bypass capacitors to pass Class B certification. Additionally, the device is rated to withstand 5.7kV RMS and has a creepage distance and clearance greater than 8mm, making it ideal for applications requiring reinforced insulation.
With continued advancements in solar technology and cost efficiency, the future of renewable energy is boundless, and new technologies are a major factor in enabling the safe and efficient production of renewable energy. ADI’s interface and isolation portfolio has several options for isolating RS-485 interfaces. The iCoupler isolated RS-485 ADM2867E provides a complete system-level EMC solution, providing system designers with a better solution that significantly reduces design complexity and ensures better EMC testing and compliance. Importantly, it meets IEC 61000 surge, EFT and ESD standards and is immune to conducted, radiated and magnetic field disturbances commonly found in harsh solar PV environments, dramatically reducing time to market for designs that need to meet stringent regulatory targets.