LEM (Switzerland) presents the CAB current transducer for (hybrid) electric vehicle battery packs. The fluxgate sensor delivers measured data via CAN to the vehicle electronics. It offers current measurement capability of up to ±400 A. The Coulomb-counting error over the driving cycle lies under 0,1 %.
THE TRANSDUCER TAKES THE FORM OF a panel-mounted module measuring 71 mm x 52 mm x 21 mm, excluding mountings, that has an aperture through which the primary (battery feed to the vehicle motors) conductor passes. It operates from the vehicle's 12-V power supply, and is rated for operation from -40 °C to +105 ºC. The sensor transmits its data to the vehicle's control circuitry using the CAN networks. Variants delivering data via other interfaces are available on request.
The fluxgate transducer uses a magnetic current-measurement principle. It is galvanically isolated and non-intrusive. No electrical connection to the power circuit is needed. This ensures safe operation and generates no waste heat or losses. To ensure long battery life, EV (electric vehicles) and HEV (hybrid electric vehicle) batteries are typically never fully discharged, or charged, and are therefore over-sized compared to their nominal rating. The sensor allows for precise state-of-charge (SOC) tracking while the battery is driving the vehicle or is charging (e.g. while braking). Thanks to the SOC estimation, vehicle designers may reduce the size and weight of the battery pack accordingly. Car manufacturers also require this data to maximize the range of the vehicle and to keep the battery in good condition.
The global mid-size provider of solutions for electrical parameters measuring celebrated this year its 40th anniversary. Its current and voltage transducers are applicable in drives and welding, renewable energies and power supplies, traction as well as in conventional and “green” cars businesses. LEM has production plants in Beijing (China), Geneva (Switzerland), Machida (Japan), Copenhagen (Denmark) and provides Swiss sales offices.
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