High-precision robust monitoring of charge/discharge current over a wide dynamic range for electric vehicle batteries using diamond quantum sensors

Abstract

Accurate prediction of the remaining driving range of electric vehicles is difficult because the state-of-the-art sensors for measuring battery current are not accurate enough to estimate the state of charge. This is because the battery current of EVs can reach a maximum of several hundred amperes while the average current is only approximately 10 A, and ordinary sensors do not have an accuracy of several tens of milliamperes while maintaining a dynamic range of several hundred amperes. Therefore, the state of charge has to be estimated with an ambiguity of approximately 10%, which makes the battery usage inefficient. This study resolves this limitation by developing a diamond quantum sensor with an inherently wide dynamic range and high sensitivity for measuring the battery current. The design uses the differential detection of two sensors to eliminate in-vehicle common-mode environmental noise, and a mixed analog–digital control to trace the magnetic resonance microwave frequencies of the quantum sensor without deviation over a wide dynamic range. The prototype battery monitor was fabricated and tested. The battery module current was measured up to 130 A covering WLTC driving pattern, and the accuracy of the current sensor to estimate battery state of charge was analyzed to be 10 mA, which will lead to 0.2% CO2 reduction emitted in the 2030 WW transportation field. Moreover, an operating temperature range of − 40 to + 85 °C and a maximum current dynamic range of ± 1000 A were confirmed.

Millimeter‐Scale Temperature Self‐Calibrated Diamond‐Based Quantum Sensor for High‐Precision Current Sensing

“…[ 27 ] Recent advances have demonstrated the feasibility of diamond sensors for current measurement, including applications in transformers [ 28 ] and automotive batteries. [ 29 ] However, compact and scalable sensors are required for mass deployment.…”

Extending Spin Dephasing Time of Perfectly Aligned Nitrogen‐Vacancy Centers by Mitigating Stress Distribution on Highly Misoriented Chemical‐Vapor‐Deposition Diamond

“…[11][12][13] In particular, sensors with large detection volumes (>(0.1 mm) 3 ) are expected to achieve high magnetic sensitivity required for biomagnetic measurements [14][15][16] and battery current monitoring. [17] DOI: 10.1002/qute. 202300194 The DC magnetic sensitivity of the ensemble NV centers can be enhanced by improving the measurement contrast (C), number of NV centers (N), and spin dephasing time (T 2 * ).…”

“…[ 11–13 ] In particular, sensors with large detection volumes (>(0.1 mm) 3 ) are expected to achieve high magnetic sensitivity required for biomagnetic measurements [ 14–16 ] and battery current monitoring. [ 17 ]…”

Compact and portable quantum sensor module using diamond NV centers

“…[3][4][5] Because the intensity of its fluorescence can be changed by a magnetic field and microwave resonance and also its coherent time is very long, 6) the possibilities of various quantum sensors were proposed. [7][8][9] Currently, various specific applications, such as NMR, [10][11][12] magneto-cardio-magnetic sensors, magneto encephalic sensors, 13) in-vehicle battery sensors, 14) cell/biological sensors 15,16) and the particle physics sensors 17,18) are under intense investigation.…”

“…After Herbschleb et al showed a pulsed NV sensing method over a wide dynamic range, 20) Hatano et al showed that the CW sensing method could also measure a wide dynamic range about the charge/discharge current of an electric vehicle battery. 14) Miniaturization is expected for use in automobiles because its microwave generator and sensor controls were performed externally on an optical bench. Mariani et al built a tabletop system for science education, making quantum operations accessible.…”