New Industry Products

Inductive Coupler “Listens” for CSS Communication in EV Charging Cables

May 11, 2023 by Mike Falter

The MICU 300A-SLF series of inductive couplers supports high-voltage EV charging cable sniffing/CSS listening to help with charging system design, operation, and interoperability.  

For any electrical system, accurately monitoring power line communications (PLC) is essential for proper operation and control. But high-voltage systems, like EV charging or power distribution, present unique challenges due to the power levels involved. 


MICU 300A-SLF Series for EV cable sniffing

MICU 300A-SLF Series for EV cable sniffing. Image used courtesy of PREMO

As one might infer from the name, sniffing is a clever technique that circumvents these limitations by using the principles of inductive coupling to measure PLC data communications without direct contact with the cable. With the proliferation of EVs and other high-voltage systems, accurate sniffing, or listening, is an increasingly important method to monitor PLC data transmitted via high-voltage cables.

To meet the growing need, PREMO has launched the MICU 300A-SLF series of inductive couplers designed specifically for the requirements of PLC data monitoring in EV charging cables.  

The series offers an extended frequency range with minimal narrowband insertion loss up to 600 kHz. 

Weighing less than 2.5 kg, a mechanical latch allows easy installation on cables up to 45 mm thick, which can conduct up to 300 A of current.  


Cable Sniffing for EV Charging

Communications between an EV and a charging station are dictated by the combined charging system (CSS) digital communication protocol per the ISO 15118-2 standard. The CSS protocol defines how EVs and charging stations communicate with each to ensure the safe charging of an EVs powertrain battery. To enable communications, the EV and charging station each have an internal, inductively coupled PLC transceiver that encodes and decodes system data, following the protocol, for bi-directional communication across the charging cable.     

Cable sniffing via an inductive coupler, like the MICU 300A-SLF, allows engineers to “listen in” and monitor real-time CSS communications between the vehicle and charging station without a direct connection to the high-voltage cable. 

Accessing CCS data directly from the cable is useful for both new platform developments (EVs and charging stations) and troubleshooting EVSE (EV supply equipment) systems already deployed in the field for issues like interoperability or interrupted charging. Real-time monitoring of CSS data from charging cables is an important capability to ensure the safe operation and design of these high-voltage systems and to identify potential problems early on before they become more serious. Access to this data is also important for system designers (EV and EVSE) to help improve the design, performance, and interoperability of EV charging operations.  

Charge system data collected by the inductive coupler is transmitted to the CSS listening hardware through an integrated BNC connector or other connector option. 

V charge cable sniffing with the MICU 300A-SLF

EV charge cable sniffing with the MICU 300A-SLF. Image used courtesy of PREMO


Other PLC Monitoring Applications

In addition to monitoring CSS communications in EV charging cables, other PLC monitoring applications for inductive couplers include AMR (automated meter reading), electric power distribution systems, and overhead power lines. 


Inductive coupler in MV/LV substation

Inductive coupler in MV/LV substation. Image used courtesy of PREMO


According to PREMO, their inductive couplers are manufactured with high permeability and performance materials to help mitigate saturation problems at high currents. 

For safety, the MICU 300A-SLF series is rated at more than 4.7 kV of insulation, meets IEC 60950 standards for safety isolation, and is water resistant to IP65 standards.