3.4.4 - High Performance Current Measurement with Low-Cost Shunts by means of Dynamic Error Correction
- 18. GMA/ITG-Fachtagung Sensoren und Messsysteme 2016
2016-05-10 - 2016-05-11
- 3.4 Elektrische Messtechnik
- P. Weßkamp, J. Melbert - Ruhr-Universität Bochum, Bochum (Germany)
- 224 - 230
Measurement of electrical current is often performed by using shunt resistors. Thermal effects due to self-heating and ambient temperature variation limit the achievable accuracy, especially if low-cost shunt resistors with increased temperature coefficient are utilized. In this work, a compensation method is presented which takes static and dynamic temperature drift effects into account and allows a correction of the measurement error. A thermal model of the shunt resistor setup is derived for this purpose and a suitable calibration method is developed. The correction algorithm is implemented in laboratory test equipment for long-term studies on automotive lithium-ion cells. For a 600 A current pulse, it reduces the measurement error from 2% to less than 0.1%. Measurements with a real-life testing profile show a reduction of remaining measurement error by 60%. The proposed dynamic error correction algorithm therefore allows high measurement accuracy despite the use of low-cost shunt resistors.