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BMW Group decides to adopt ams AG’s integrated automotive sensor interface, AS8510, to provide extremely accurate battery voltage and current measurements in its “i3” series electric vehicles (EVs).
The BMW i3 model that is in volume production will include an AS8510 in the battery sensor. The battery management system (BMS) monitors battery voltage and battery current of the 400V li-ion battery powering the cars’ electric motors, and ensures the functional safety of the vehicle’s battery systems.
Optimization of energy management is essential for EVs to provide reliability when being driven. Accurate current and voltage measurements enable the BMS to make a highly accurate calculation of a li-ion battery’s State Of Charge (SOC), meaning that the drivers can accurately grasp and estimate how long the vehicle can travel. When backed by a special calibration scheme, the sensor system in the BMS is able to measure current to an accuracy of just ±0.5% and voltage to an accuracy of better than ±0.1% over the full operating temperature range.
Features of the AS8510 include a full operating temperature range of -40°C ~+125°C, zero-offset architecture, low noise, high linearity, multi channel architecture and low drift. These features make it a suitable choice for the i series. The AS8510 provides integrated data acquisition front ends, which include two independent 16-bit sigma-delta ADCs. Measuring current across a shunt resistor in one channel over a range from a few milliamps up to 1kA, it provides a digital output via a serial peripheral interface. Through the second channel it can capture three different voltage sources simultaneously with current samples.
The AS8510 is fully compliant with the AEC-Q100 standard. The device supports the functional safety compliance efforts of car manufacturers in line with the requirements of the ISO26262 standard.
“The techniques for monitoring the SOC and the State Of Health (SOH) in EV batteries are constantly being refined and improved, and BMW has set a new benchmark in battery management system design in the new i3 model. ams is proud to have supported BMW’s advanced implementation of ultra-accurate battery parameter measurement in the demanding environment of a vehicle drivetrain,’ said Bernd Gessner, Vice-President and General Manager of the automotive business unit at ams.
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