Electrical measurement technology firm LEM has designed an automotive-grade residual current monitoring (RCM) type B sensor for bidirectional onboard EV chargers (OBCs).

The new RCM type B sensor is designed to enable EV system engineers to progress towards transformer-less OBCs in a single unit while speeding up design architecture as it is ISO26262 Automotive Safety Integrity Level B (ASIL B) ready. This type of RCM is suitable for complex electrical systems, especially those found in EVs with DC components, and it can detect potentially hazardous leakage currents.

The sensor is suitable for use with bidirectional OBCs that allow vehicle-to-everything (V2X) applications, including vehicle-to-load (V2L), powering external devices, vehicle-to-grid (V2G), supplying energy to the grid and vehicle-to-vehicle (V2V), enabling communication between vehicles.

LEM’s new CDT detects differences in current between two points, identifying faults such as short circuits and enabling rapid isolation of faulty sections to prevent damage. It works in combination with the RCM type B for bidirectional OBCs, where residual currents are detected and monitored, including AC and DC leakage currents.

If the DC fault current is greater than 6 mA in an OBC, there is the potential to compromise the detection and tripping capabilities of a Type A RCD, which could increase the risk of electric shock. A Type B RCM can measure and detect AC and smooth DC. The new CDT sensor has been designed to meet this demand by combining automotive grade with a high level of accuracy of ± 0.5 mA @ 5 mA, enabled by LEM’s multi-patented fluxgate technology.

LEM’s latest sensor also features advanced functions on the secured Serial Peripheral Interface (SPI) bus including dynamic fault selection, monitoring of T° C, leakage value and supply monitoring. Additional features include advanced diagnostic functions and the ability to work equally effectively with single-phase and three-phase AC.

“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,” said Clément Amilien, LEM’s Head of Global Product Management Automotive.

Source: LEM International