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Overview current measurement
Assistance systems support the driver and assure safety in the latest generation of automobiles. Infotainment systems entertain passengers during car journeys and provide navigation. Seats are no longer adjusted manually, and doors are opened and closed with electric motors. The ever increasing electrification is driven by many other factors besides convenience and safety though. Optimization of consumption and emissions reduction always pose new challenges for drivetrain development, where currents need to be measured.
Why is current measured?
Current and voltage spikes can always occur in on-board power supplies, e.g., due to a sudden interruption of current in an electronics module, where the vehicle voltage can temporarily rise to a multiple of the nominal voltage. The duration of such a voltage spike is typically only a few fractions of a millisecond, but this is still enough to damage electronic components in the vehicle. Precise measurements are needed here to record the current and voltage characteristics of all electrical components. Another reason why electrical current is exclusively measured is to compare nominal and actual current values. This is done whenever electrical currents are used to drive electromechanical automobile components.
Besides current measurement, the power input and efficiency of individual components and their response over time are also critically important. Complete solutions for highly dynamic power measurement are called for here. As synchronous a measurement as possible of the two quantities are needed here, given that power is the product of current and voltage. The efficiency of an electrical system can thus be assessed in detail by examining the power losses along the drivetrain in a hybrid or electric car.
Where is current measured?
Measurements are taken in high-voltage environments, like the electrical drivetrain, in electric and hybrid vehicles. This includes components, like the electric-vehicle battery, the inverter or the electric motor, all of which carry high currents. This requires increased safety awareness on the part of all stakeholders.
Clearly, current and power measurements can be performed on all electrical systems and auxiliary devices. Aside from measurements on “classical” electrical loads, like vehicle lighting (headlights, brake lights, etc.) or heating (seat heaters, PTC heaters, etc.), measurements are also taken on electrified components that were heretofore mechanically operated. Here are some examples of such components:
Electrical power steering
Electrical pumps (e.g., water and fuel pump)
Electrical turbochargers / compressors
LEM LF 310-S sensor package
Hall-effect-based measurement of highly dynamic currents under harsh environmental conditions: the LEM-sensor package is optimized for connection to our ECAT ADMM modules.
Shunt-based current measurements under harsh environmental conditions: The CSMshunt device family extends the application range of CAN- and EtherCAT®-based AD MiniModules from CSM.