LEM introduces the first automotive-grade residual current monitoring (RCM) type B sensor for bi-directional on-board chargers (OBCs), designed to meet ISO5474 Part 2 standard for AC power transfer. The new CDT sensor enables EV system engineers to create transformer-less OBCs while ensuring compliance with safety standards, improving efficiency, and reducing weight and cost.
Key Highlights:
- Bi-Directional OBC Safety: Supports vehicle-to-everything (V2X), including vehicle-to-load (V2L), vehicle-to-grid (V2G), and vehicle-to-vehicle (V2V) applications.
- ISO26262 ASIL B Ready: Speeds up design architecture, meeting automotive safety integrity level requirements.
- Compliance with ISO5474 Part 2: Ensures safety and functionality for AC power transfer between vehicles and external circuits.
- Fluxgate Technology: Provides high accuracy of ± 0.5 mA @ 5 mA for effective leakage current detection.
- Advanced Diagnostics: Features dynamic fault selection, temperature monitoring, and SPI bus secured communication.
The new CDT sensor from LEM is the first automotive-grade RCM type B sensor with ASIL B capabilities, tailored for bi-directional OBCs. It addresses critical safety challenges inherent to these OBCs, allowing engineers to monitor leakage and comply with stringent safety standards. The CDT sensor also meets the requirements of the ISO5474 Part 2 standard for AC power transfer, an essential guideline for electrically propelled road vehicles. The standard outlines the functional and safety requirements for transferring power between a vehicle and an external circuit using AC, covering conductive charging for modes 2 and 3, reverse power transfer, and voltages up to 1000V AC.
The bi-directional OBC design brings new challenges, such as high voltage safety, which includes leakage monitoring and compensation. LEM’s CDT sensor provides a solution that meets these safety requirements while enhancing design flexibility, reducing weight, and maintaining cost efficiency. This new sensor is crucial for enabling V2X applications, where the vehicle battery serves as an energy source not only for the vehicle itself but also for external devices, the electric grid, and other vehicles.
The CDT sensor’s high precision fluxgate technology offers an unprecedented level of accuracy (± 0.5 mA at 5 mA), enabling precise detection and rapid isolation of faults such as short circuits. Fluxgate sensors are particularly suitable for environments where precise magnetic field measurements are essential, providing stable measurements across a wide range of temperatures and environmental conditions.
Other key features of the CDT sensor include advanced diagnostic capabilities via a secured Serial Peripheral Interface (SPI) bus, which ensures encrypted and authenticated data transmission. This enhances the overall safety of the system by enabling real-time temperature monitoring, leakage value tracking, and supply monitoring. The sensor can operate effectively with both single-phase and 3-phase AC power sources.
According to Clément Amilien, LEM’s Head of Global Product Management Automotive, “The new ISO5474 Part 2 standard for AC power transfer relates to using an EV as an AC energy source. This means it is essential to have the capability of monitoring leakage currents in vehicles. The standard also dictates that V2L applications require safety protection for socket outlet usage through RCM. Our new CDT sensor has been designed to ensure safety for V2X functions with automotive ready RCM type B. It has an ASIL B ready option and is intended to satisfy all EV system designers’ OBC challenges in a single, easy to design-in package. This new sensor will help them to accelerate their time to market while complying with all security and safety regulations for V2X applications.”
LEM will showcase its portfolio for automotive, including motor control, Battery Management Systems (BMS), and residual current monitoring solutions, at Electronica in Munich, from November 12 to 15, 2024, in hall B3, booth 441.
About LEM: LEM is a global leader in electrical measurement technology, developing solutions to ensure energy and mobility systems are optimized, reliable, and safe. With over 1,800 employees across 17 countries, LEM focuses on megatrends such as renewable energy, mobility, automation, and digitization. LEM has been listed on the SIX Swiss Exchange since 1986 under the ticker LEHN. For more information, visit www.lem.com.
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