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

the Hipercar will qualify as a zero- emissions vehicle. The Cat Gen’s 35 kW is a continuous rating, while the core hardware weighs 50 kg and the coupled DC generator can supply current at a wide range of voltages. Ariel claims a range of 150 miles on the WLTP cycle, and more with use of the range extender, which can be switched on and off manually or automatically under the control of the BMS. The car can also be charged from existing home or public power outlets. Compatible with CHAdeMO and Type 2 hardware, the split charging system enables the car to use outlets designed for less than 500 V while being ready for 800 V infrastructure when it arrives, says the company. Bespoke spoke motors While rear-wheel drive is an option, the Hipercar prototype is fitted with four custom-designed 220 kW APM-200 interior permanent magnet radial flux spoke motors from Equipmake. Mounted inboard and spinning at up to 10,000 rpm, each motor has an integrated inverter and single-stage 5.43:1 epicyclic reduction gearbox producing a maximum output speed of 1842 rpm. The motor weighs 40 kg, its reduction gearbox 9 kg and the inverter adds 12 kg. In a spoke motor, the magnets are arranged like the spokes of a wheel, explains Ian Foley, Equipmake’s founder and managing director. “It’s an architecture known to give the highest combination of torque and power density, and we believe our motor is of comparable torque density to the best axial flux motors,” he says. He explains that while the magnets in a conventional radial flux motor tend to be arranged in vee shapes around the rotor, the magnets in a spoke motor are “vertical”, lining up radially around the rotor. The flux comes out of either side of each magnet and then through the laminations of the rotor. “The flux path is radial, but the way the flux is generated by the magnet arrangement is different and gives what we believe is a better use of the flux,” he says. He adds that the design benefits from the more established techniques for manufacturing radial flux motors, and that the architecture makes it easier to get liquid coolant under the base of each magnet, allowing the motor to achieve higher continuous power without overheating. The integral inverter developed to drive the APM-200 is the HPI-450, which incorporates IGBT power electronics. However, it is also available with silicon carbide diode technology combined with IGBTs to improve its power transmission and enable it to run at high switching frequencies. Designed to run at 750 V DC, it has a peak current rating of 450 A rms. In its current state of development, the Hipercar has adjustable traction Although the range extender is a gas turbine, it is not a conventional one. Delta Cosworth calls the device its Catalytic Generator (Cat Gen), because the exothermic chemical reaction between the fuel and the air is promoted by a catalyst rather than being ignited by a spark and sustained by the continuous flame, as happens in a conventional gas turbine. Johnson Matthey supplies the catalyst. To start the turbine, an electric motor spins the compressor, shaft and turbine up to 30,000 rpm, an electric heater brings the catalyst up to temperature and the fuel is injected. With the reaction under way, the machine spins up to a steady 110,000 rpm. At the moment, the Cat Gen runs on petrol, but Delta Cosworth notes that using it as a battery charger allows it to run at an optimised speed and load, and that the catalytic reaction can be controlled very precisely. Together, these factors ensure that emissions are reduced to “negligible levels” without after-treatment. The device will run on any liquid or gaseous fuel, but in the long term the intention is to run it on hydrogen, when The Hipercar is fitted with two of these twin APM-200 propulsion modules, each with two high torque-density radial flux spoke motors and integral inverters (Courtesy of Equipmake) 56 January/February 2023 | E-Mobility Engineering