E-Mobility Engineering 017 l ECE Doosan electric excavators dossier l In Conversation: Matt Faulks l Battery testing focus l Battery Show North America 2022 report l Ariel Hipercar digest l Cathode materials insight l Thermal management focus

Quantum leap for cell current tests R esearchers in Japan have used a quantum sensor with a wide dynamic range and high sensitivity to measure the current in a battery pack more accurately than traditional techniques (writes Nick Flaherty). The team, from the Department of Electrical and Electronic Engineering at the Tokyo Institute of Technology, took a quantum sensor built from artificial diamond and used microwaves to excite the nitrogen vacancies in it to pick up minute changes in the current. The design uses two sensors to give a differential detection of the current to eliminate in-vehicle common-mode environmental noise. The battery current of EVs can reach several hundred amps, while the average current is only about 10 A, but ordinary sensors do not have an accuracy of several tens of milliamps while maintaining a dynamic range of several hundred amps. That means the state of charge has to be estimated, generally with an ambiguity of about 10%, which makes the battery’s usage inefficient. This reduces a vehicle’s effective range. The researchers attached a prototype monitor with a 1 GHz analogue-to-digital mixed-signal controller to the busbar of a battery pack to trace the magnetic resonance microwave frequencies in the sensors. The monitor measured the current from a battery module up to 130 A with an accuracy of 10 mA using a standard driving pattern. Despite the sensitivity, the monitor is accurate over an operating temperature range of -40 to +85 ºC with a maximum current dynamic range of ±1000 A. K eysight Technologies has updated its regenerative DC emulator to support higher power up to 270 kW for powertrain testing (writes Nick Flaherty). The Scienlab SL1800A Series regenerative DC emulator enables engineers to emulate the large batteries in EVs. The bidirectional power flow allows emulation of power sourcing applications such as traction inverter tests, as well as power sink applications such as EV charging. The regenerative design uses silicon carbide MOSFET transistors to allow the power absorbed to be delivered back to the grid, giving 96% efficiency so that only 4% of the energy is lost as heat. This reduces the energy and cooling costs, and allows the smaller footprint of 2150 x 2410 x 600 mm for the more powerful systems, the SL1820A to SL1840. The SL1800A Series is integrated with the SL1040A Scienlab charging discovery system (CDS) and SL1093A charging discovery software, which fully automates DC charging applications for many different test standards up to 1500 V and 900 A with an accuracy of ±0.03% for both. The modular CDS enables the testing of EV charging interfaces and EV supply equipment (EVSE) by replacing multiple real EV/EVSE interfaces with one test system. That provides automated functional, conformance, interoperability and quality testing with time-synchronous measurement and decoding of comms and power signals for the CharIN CCS CHAdeMO and GB/T interface standards. The software also allows the SL1800A systems to be used in parallel to emulate loads of up to 1.5 MW for truck and construction equipment powertrain development. BATTERIES The dual quantum sensors boost the accuracy of current measurements Keysight’s updated DC emulator is suitable for applications such as traction inverter tests Emulator hands power back to grid POWERTRAIN TESTING January/February 2023 | E-Mobility Engineering 7 TheGrid