The Hipercar uses four electric motors (APM200), one for each wheel, and developed by project partner Equipmake in cooperation with Aim Co Japan. The motor features a unique rotary design in a lightweight aluminium architecture.
Weighing just 40kg each, the motor develops 220kW and 450Nm of torque, thanks to the patented rotor design that produces a 25 per cent increase in torque density compared with a conventional rotor. It also means, there’s 25 per cent magnet material required to meet the torque target.
The unique design features direct cooling for the magnets by water glycol, which allows for very high sustained power delivery. It’s also one of the lightest, highest power and torque-rich motors available in the automotive sector.
The Hipercar uses a lightweight, fully-integrated single-speed transmission weighing just 9kg. It features a reduction of 5.5:1 producing 2475Nm per wheel.
The gears are helical cut, reducing noise under load, and have asymmetric tooth profiles and topological modifications that ensure lasting durability while under stress. And, in a bid to save weight and space, the cooling system is shared by the gearbox and the motor.
Motor Inverters and Power Electronics
The bespoke inverters were also developed by Equipmake to meet the specific requirements of the Hipercar motor, and as such, sits immediately above the motor resulting in reduced transmission losses in the connector cabling, less weight and improved EMC performance (Electromagnetic Performance).
The car also uses the latest Silicon Carbide Power Electronic Switch technology, resulting in a 30 per cent reduction in losses compared with other forms of switching. The motor controller allows the torque of the motor to be updated 14,000 times per second.
Vehicle Dynamic Control – Torque Vectoring
With so much power and torque available at each wheel, it’s vital that its delivered in a measured fashion – both from a performance and safety aspect, which is why Delta Motorsport has developed a sophisticated system that ensures the huge capability for twin axle torque distribution is evenly applied to maximise performance.
The Hipercar will be offered with two different battery packs; the four-wheel-drive version developed by Delta Motorsport, gets a peak system voltage of 750V, via a high power-density 26650 lithium-ion cell, to accelerate a peak current draw of 1200 Amps and maximum power competency of over 1500kW.
The two-wheel drive variant uses a different drive cycle for slightly reduced performance targets. Developed under the UK’s AMPLiFII (Automated Module-to-pack Pilot Line for Industrial Innovation) project led by the Warwick Manufacturing Group, it uses a smaller 18650 lithium-ion cell that generates a nominal 648V and 56kWh capacity with a peak power draw of 1050 Amps.
Thermal management of the packs is controlled by using Refrigerated water-glycol coolant, which is fed directly to every cell in the pack in even proportions. Heating and cooling demands are managed by numerous temperature sensors fitted throughout the pack.
Battery Control Systems
The critical job of battery management solution was engineered by partners Delta Motorsport and Potenza Technology.
Each battery pack contains 67 battery modules, and each module has its own data capture board that both monitors and manages the voltage of each parallel cell group. Multiple measurements are sent to the battery master controller that makes key decisions around parameters such as power limits, cooling and current flow.
Delta Motorsport has developed a 35kW micro-turbine system specifically for the Hipercar. The gas-driven turbine runs at a fixed 120,000 rpm, operating at a nominal 750V to maintain charge. The battery management system switches the turbine on and off, depending on requirements, and weighs less than 50kg, so it's significantly smaller and lighter than a piston engine alternative. In addition, the combustion system incorporates a recuperator that limits emissions to well under legal requirements.
In addition to the range extender, the Hipercar also has provision for recharging with existing quick-charging CHAdeMO infrastructure and Type 2 hardware.
With so much power available (up to 1MW) between the four wheels, it’s crucial that the vehicle is able to recapture the kinetic energy when off the throttle. In the Hipercar, the recharging is done by each wheel motor.
The same water-glycol heating and cooling system for the battery packs is also used for air-conditioning system, power electronics and drivetrain. For further efficiency around space and weight, some systems share hardware such as pumps, header tanks and the lightweight aluminium radiators. The management system itself is designed to operate in a temperature range between -20 degrees and 45 degrees Centigrade.
The Hipercar uses a bonded aluminium monocoque (laser cut and CNC folded) with a high strength rollover cage. The front and rear subframes are removable and provide a crush structure as well as mechanical mount points.
The battery pack is mounted as low as possible under the floor and central tunnel, and within the wheelbase for the lowest possible centre of gravity, as well as security. In addition, there’s a machined aluminium cover that secures the battery to the chassis.
NVH has been carefully examined and refined by ASDEC, part of Leicester University, ensuring optimum cabin comfort.
Advanced CFD (Computational Fluid Dynamics) not unlike those applied to Formula One and high-level sports car racing have been applied to the Hipercar for minimum drag, cooling efficiency and downforce requirements.
The next phase of the car’s development will involve feeding in all that was learned from the Atom AERO-P project, which deals with the generation of downforce at zero speed.
The Hipercar will become the first fully enclosed car for Ariel, and the skin will be a combination of carbon-fibre and other lightweight materials. The finished design will focus on light weight, which itself will dictate the car’s exterior design.
Gullwing doors will enhance ingress and egress, as well as provide structural stiffness and protection from the relatively high sills for all levels of drivers.
While the cabin interior design is yet to be finalised, lightweight, comfort and good ergonomics are key priorities.
The bespoke seats, made specifically for the Hipercar by Seat Design Company in Derbyshire will be shown in the prototypes, though the final production version will get a refinement of these.
The reclining seats will feature a carbon-fibre tube construction and pressure mapped design with integral seat belt mounts, and weight just 9kg each. Driver instrumentation will boast two TFT displays supporting manual and touchscreen functionality.
The Hipercar gets unequal-length double wishbones all round – machined from aluminium billet for precision, strength and weight saving properties.
The dampers are by Bilstein UK, and feature independent adjustment of compression and rebound. The addition of Vehicle Dynamic Control will enable drivers to tune the handling to suit the driving style and conditions.
Steering is a bespoke power assist system specifically engineered for the Hipercar, with Ariel Atom accuracy and feedback an absolute priority. There’s a 330mm steering wheel with adjustable reach and rake, giving 2.25 turns to lock.
Braking is by AP Racing and uses 370x32mm ventilated and grooved front discs with six-piston calipers up front, and 328x30mm discs with four-piston calipers down back. The brake pedal is machined from aluminium billet and includes an adjustable ratio via an electric servo for maximum feel and feedback. The park brake is manual via individual lightweight Brembo calipers.
The Hipercar doesn’t employ regenerative braking, so as to maintain feel and predictability of the brake pedal at all states of battery charge.
Wheels and Tyres
Final tyre composition has not been finalised, but the huge power and torque generated by the car will be transferred to the road through via forged lightweight wheels (9.5Jx20 front, 12.5ZJx21 rear), shod with Michelin Pilot Sport Cup 2 Tyres in 265/35/20 up front, and 325/30/21 down back.
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