Giant Step from Japan in Electric Vehicle Batteries

Giant Step from Japan in Electric Vehicle Batteries
Giant Step from Japan in Electric Vehicle Batteries

With researchers from Tokyo Tech and Yazaki Corporation, they are running the MEXT Q-LEAP Flagship Project. The diamond quantum sensor prototype created as part of this project can finally put an end to the problem of battery usage inefficiency caused by faulty battery charge measurement in electric vehicles. The sensor can detect milliamp currents in a noisy environment and can measure currents over a wide range, increasing the detection accuracy from 10% to 1%.

Electric cars (EVs) are increasingly being chosen as an environmentally beneficial alternative to conventional fuel cars. As a result, research is being done to create high-efficiency electric vehicle batteries. But EVs suffer from significant inefficiency as a result of incorrect battery charge estimates. Based on the current output of the battery, the state of charge of an EV battery is determined. This gives an estimate of the remaining driving range of the vehicles.

Battery currents in electric vehicles can often approach hundreds of amperes. However, commercial sensors cannot measure small changes in current at milliamperage levels. As a result, there is an estimated 10% uncertainty in battery charge.

This shows that the driving range of electric vehicles can be increased by 10%. This will result in less inefficient battery usage.

Fortunately, a group of scientists from Japan under the direction of Professor Mutsuko Hatano from Tokyo Institute of Technology (Tokyo Tech) recently discovered a cure. In their paper published in Scientific Reports, the scientists described a sensing method based on diamond quantum sensors that can measure the strong currents typical of electric vehicles and predict battery charge with 1% accuracy.

“We have created diamond sensors that are small enough to be used in automobiles and sensitive to milliamp currents. We also detected milliamp currents in a loud environment and measured currents over a wide range,” says Professor Hatano.

Two diamond quantum sensors placed on either side of the bus (the electrical connection for currents to and from the car) were used by the researchers to create a prototype sensor for their study. The common noise picked up by both sensors was then removed using a method known as "differential sensing", leaving only the actual signal. As a result, they were able to distinguish a small current of 10 mA from the surrounding noise.

Next, the scientists monitored the quantum sensor's magnetic resonance frequencies across the 1 gigahertz bandwidth using a hybrid analog-digital control of the frequencies produced by the two microwave generators. This results in a wide dynamic range of about 1000 A (the ratio of the largest detected current to the smallest current).

It has also been found that a wide operating temperature range of 40 to +85°C will cover most vehicle applications.

Finally, the group submitted this prototype to the WLTC (Worldwide Harmonized Light Vehicles Test Cycle), a benchmark test for electric vehicle energy consumption. The sensor accurately tracks charge/discharge current from -50 A to 130 A, exhibiting battery charge estimation accuracy within 1%.

What conclusions can be drawn from these findings? Professor Hatano says: “With 10% reduction in battery weight and 10% increase in battery consumption efficiency, by 2030, 20 million new electric vehicles will need 3,5% less energy to power and 5% less energy to produce. As a result, this will increase CO2030 in the transport sector by XNUMX.will lead to a 0,2% reduction in emissions.”








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