We are super excited to see how quantum technology is benefiting green technology! Quantum sensors in diamond have been used to monitor the energy stored in electric vehicle batteries much more accurately than previously possible. This could significantly improve the range and energy efficiency of electric vehicles.
Today, the remaining energy in batteries is estimated by measuring the electric current flowing through the batteries while driving. Although these currents can reach hundreds of amperes, their average value is usually only around 10 A. Therefore, sensors must operate over a wide dynamic range, which makes them very susceptible to ambient noise.
The noise in battery measurements
This noise means that the remaining energy of a battery can only be estimated with an accuracy of about 10%. To be safe, EV batteries must therefore be recharged once they have dropped to 10% of their energy capacity. This significantly limits the range of an electric vehicle and means that heavier batteries are required to achieve any target distance range.
Differential measurement by diamond sensors
In their study, the researchers attached a pair of diamond sensors to both sides of an EV bus bar. This is a thick metal strip that connects a vehicle's battery to its motors and other electrical components. When a current flows through the bus bar, it creates a magnetic field that can be measured by the two diamond sensors. Since the sensors are on both sides of the busbar, one sensor measures a positive value for the magnetic field and the other a negative value. They both measure the same noise level - so subtracting one measurement from the other eliminates the noise.
Using this noise reduction technique, the team was able to measure currents in the bus bar as high as 130 A and as low as 10 mA - even in a noisy automobile environment. The team then increased the current to ±1000 A and operated the sensor in a temperature range of -45 °C to 85 °C, observing good measurement performance.
The team says the sensors could reduce the weight of electric car batteries by 10%, which would reduce the energy required to run and produce electric cars. The team estimates that commercial deployment of the sensors could reduce carbon dioxide emissions from the transport sector by about 0.2% by 2030 - bringing it one step closer to the goal of zero carbon dioxide emissions.
Do you want to learn more about quantum sensing in battery management? Reach out to our technology specialist Fleming Bruckmaier!