Summary
- LEM designed an automotive-grade residual current monitoring (RCM) type B sensor for bidirectional onboard EV chargers
- The sensor enables EV system engineers to progress towards transformer-less OBCs in a single unit
- It is suitable for complex electrical systems, especially in EVs with DC components
- The sensor can detect potentially hazardous leakage currents and faults such as short circuits
- The sensor features advanced functions on the secured Serial Peripheral Interface (SPI) bus and ASIL B-ready option
Article
LEM has developed a automotive-grade residual current monitoring (RCM) type B sensor specifically designed for bidirectional onboard EV chargers (OBCs). This new sensor allows EV system engineers to move towards transformer-less OBCs in a single unit, while also accelerating design architecture. The sensor is ISO26262 Automotive Safety Integrity Level B (ASIL B) ready and is ideal for complex electrical systems, especially those found in EVs with DC components. It has the ability to detect potentially hazardous leakage currents within the system.
The RCM type B sensor from LEM is compatible with bidirectional OBCs that support vehicle-to-everything (V2X) applications, including vehicle-to-load (V2L), vehicle-to-grid (V2G), and vehicle-to-vehicle (V2V) communication. This sensor plays a crucial role in detecting and monitoring residual currents, including AC and DC leakage currents. It works in conjunction with a current differential transformer (CDT) to identify faults such as short circuits and enable quick isolation of problematic sections to prevent damage.
In scenarios where the DC fault current exceeds 6 mA in an OBC, a Type A Residual Current Device (RCD) may face challenges in terms of detection and tripping capabilities, increasing the risk of electric shock. The Type B RCM, however, is capable of measuring and detecting both AC and smooth DC currents. LEM’s CDT sensor boasts a high level of accuracy of ± 0.5 mA @ 5 mA, thanks to the company’s patented fluxgate technology, making it a superior solution for addressing these challenges in EV systems.
The new CDT sensor from LEM includes advanced functionalities on the Serial Peripheral Interface (SPI) bus, such as dynamic fault selection, temperature monitoring, leakage value monitoring, and supply monitoring. Additionally, it offers advanced diagnostic functions and can seamlessly work with both single-phase and three-phase AC systems. These features, combined with the automotive-grade reliability and safety of the sensor, make it an ideal solution for ensuring safety in V2X functions and complying with all security and safety regulations for EV applications.
Clément Amilien, Head of Global Product Management Automotive at LEM, emphasized the importance of the new CDT sensor in providing safety for V2X functions with its automotive-ready RCM type B. By offering an ASIL B-ready option and addressing various OBC challenges in a single, easy-to-design package, the sensor enables EV system designers to expedite their time to market while meeting all security and safety requirements for V2X applications. This innovation from LEM is set to streamline the development process for EV charging systems and improve overall safety in the automotive industry.
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