Page 116 - NEW Armstrong Book - 2

At the heart of the Evija is an ultra-advanced all- electric powertrain developed by technical partner Williams Advanced Engineering. Williams is known for its success in motorsport, from Formula One to electrifying the first four seasons of Formula E. The battery pack is mid-mounted immediately behind the two seats and supplies energy directly to four independently controlled high-power– density e-motors. These feature integrated silicon carbide inverters and an epicyclic transmission on each axle of the four-wheel–drive powertrain.
The motors and inverters are supplied by Integral Powertrain Ltd. Four compact, extremely light, and highly efficient single-speed, helical gear ground planetary gearboxes trans- fer power to each driveshaft. Each gearbox comes packaged with the e-motor and inverter as a single cylindrical electri- cal drive unit. With a target power of 500 PS (approximately 493 HP) per e-motor, it is the most efficient and elegant engi- neering solution to deploying so much power with precision.
Torque vectoring, enabled by the four e-motors, provides good dynamic response and agility on the road. This fully automatic, self-adjusting system can instantly distribute power to any combination of two, three, or four wheels within a fraction of a second. In track mode, the ability to add more power to individual wheels enables the radius of corners to be tightened, potentially reducing lap times.
Kerr told me that the biggest challenge in the electronics design was the complexity of the control logic to enable optimal control of each axle. He added that the Evija had a full cloud-connected computing solution behind it. The main aim for this is to be able to monitor cars, which might be
THE LOTUS EVIJA IS AN ALL-ELECTRIC HYPERCAR CURRENTLY IN THE PROTOTYPE PHASE. (SOURCE: NITIN DAHAD)
anywhere in the world, and to be able to reliably predict when a customer might need car servicing so that relevant support can be provided.
Weight reduction: the holy grail
Common themes among the manufacturers at Goodwood were minimizing system weight to improve power delivery efficiency, intelligent airflow management to reduce drag and improve performance, and effective delivery of power to the axle for precision control by the driver.
McLaren, which showcased its new Artura, said minimiz- ing weight was key to the design of the all-new electrified powertrain, engineered to offer the advantages of internal combustion and electric power in one package and establish new benchmarks for combined performance and efficiency in the supercar class.
THE MCLAREN ARTURA E-MOTOR WEIGHS 15.4 KG, ONLY A LITTLE HEAVIER THAN A CONVENTIONAL IRON ROTOR COMPONENT. (SOURCE: MCLAREN AUTOMOTIVE)
The axial flux design of its e-motor is one of Artura’s bench- marks. The e-motor is similar in size to a McLaren brake disc, and at just 15.4 kg, it is only a little heavier than a con- ventional iron rotor component, yet it can generate up to 95 PS and 225 N-m as well as enable journeys of up to 30 km in near-silent pure-EV mode. Providing the electric- only capability is a 7.4-kWh five-module lithium-ion energy- dense battery pack. Fully integrated into Artura’s McLaren lightweight architecture (MCLA) chassis, the battery pack is positioned low in the car behind the driver, incorporated into the floor, and protected on three sides by the main carbon fiber structure and from behind by the engine. This position- ing helps to optimize both the center of gravity and the polar moment of inertia, benefiting dynamic agility.
The hybrid battery sits on a cooling manifold, which is shared with the new electric heating, ventilation, and air condition- ing system also used to control air temperature in the cabin. Incorporating technology first developed for the McLaren Speedtail, the batteries are thermally controlled using dielec- tric oil — a technology also used to keep the e-motor
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