A wide dynamic range diamond quantum sensor as an electric vehicle battery monitor

Abstract

To demonstrate the application capability of the diamond quantum sensor as an electric vehicle (EV) battery monitor, we (i) investigated the measurable current in a real car noise level and (ii) compared the linearity with conventional sensors. Consequently, (i) we could measure a 20 mA current pulse even under an external magnetic field of 80 µT, which is larger than that of 50 µT around the EV battery module in a real car during driving. The 20 mA pulse measurement corresponds to the EV battery state of charge estimation accuracy of 0.2% in the standard driving pattern, which is smaller than the present level of 10%. (ii) The linearity degradation seen in the Hall sensor near the upper limit of the measurement range was not seen in the diamond sensor. Although the Hall sensor and the shunt resistor showed linearity degradation in the current range of several tens of amperes or less, the degradation was smaller for the diamond sensor. The transverse magnetic field effect in the diamond sensor on the linearity was estimated to be less than 0.01% for a several-degree misalignment of the sensor surface to the magnetic field direction and under a 340 A current. This article is part of the Theo Murphy meeting issue 'Diamond for quantum applications'.

A special issue preface: diamond for quantum applications

“…The use of highly sensitive NV diamond for magnetometry in real world environments is also an area of current research interest. Hatano et al [ 12 ] describe one such application, where the diamond quantum sensors based on NV centres are used as an electric vehicle battery monitor. They characterized the performance and noise in a real car and compared the prototype diamond sensors favourably or on par with conventional sensors such as Hall sensors and shunt resistors.…”