31 the copper and layering on the thermally conductive resin,” he says. After defining the active parts of the motor, the virtual validation process then made use of ANSYS to analyse the designs for mechanical and thermal regulatory compliance, after which IFPEN proceeded to produce production drawings for the motor components to be prototyped. Motor testing Systematic tests of all key motor components were performed, up to the point of validating the motor via in-vehicle trials. For instance, the choice of magnet model (being critical to the motor’s performance parameters, as well as one of the first components that the consortium needed to buy) was tested at IFPEN, analysed in a histogram and compared against the specifications in its algorithm-derived drawings. “IFPEN used a rotor test bench to measure the air-gap induction generated from the assembled magnets within the rotor,” Milosavljevic says. “Starting with those results, we confirmed key predictions we’d gained during performance simulations from the design phase. Then the stator winding realised at EREM was tested for insulation, resistance values and resistance equilibrium between phases. Those results were compared as early as possible with design-phase predictions done by IFPEN.” The complete rotor assembly has been trialled successfully in IFPEN’s endurance and fatigue testing cell, with the goal of validating the result of the entire rotor development and manufacturing process through exhaustive high-temperature speed cycling (from 0 rpm to its 8000 rpm maximum) featuring overspeeds. IFPEN notes that getting a passing grade for the rotor’s manufacturing quality from such tests was vital before going on to assemble the complete motor. “While that 8000 rpm is higher than what the snow groomer needs, it’s important for us to design the motor to run at such speeds for future use in buses and trucks, where their transmissions are designed for running off higher shaft speeds than the snow groomer’s is,” Milosavljevic notes. The motor’s housing is IP55-rated and built from an aircraft-grade aluminium, with two deep-groove ball bearings (one at the front and one at the back) that are fully sealed, have preloaded springs and are designed for a lifetime, greased operating temperature range of -40 C to 180 C. The completed motor was verified in high-voltage insulation tests, surge tests, waterproofing tests and more, before going into a full torque and power-test cell with the inverter, where the complete mapping of the motor and inverter performances was performed, through peak and continuous performance conditions. Once the complete powertrain was validated, it was integrated into the snow groomer, and tested in functional and performance procedures by GCK Mobility. Results thus far indicate a peak efficiency of 95.9% across the installed, finished powertrain with motor and inverter combined. Future In addition to now running tests in the French Alps, the project partners are moving towards homologation (certification) of the H2D2 snow groomer by the French authorities. The consortium aims to commence the full commercialisation and supply of units of the snow groomer as a retrofit kit in the beginning of 2025, so extensive testing in real-world ski-slope conditions is to continue throughout this year, with final modifications and adjustments by Q1 2025. Adaptations of the kit for use in a broader array of heavy commercial vehicles can be expected in the years ahead. Meanwhile, the group has a ready market of hundreds of ski slopes in France, which will want its snow groomer fleets electrified. One can expect it to cast its eyes to overseas markets once regulating bodies across Europe, the Americas and Asia provide pathways for electric snow groomers and other equipment to be safety-rated for use on winter sporting courses. Key vehicle specifications and suppliers H2D2 snow groomer Retrofitted PistenBully 600 Hydrogen-electric PEM fuel-cell range extender NMC 21700 cylindrical battery cells SiC inverter PMSR motor Dimensions: 9 m x 3.5 m x 3.2 m (excluding implements) Weight: 11 t Maximum speed: 15 kph Maximum power: 320 kW Maximum energy storage: 90 kWh approx. in battery pack, 50 kg (1680 kWh estimated) in hydrogen tanks Maximum electric powertrain efficiency: 95.9% Maximum incline in operations: 45° Original snow groomer vehicle: Kässbohrer Powertrain assembly and integration: GCK Mobility Powertrain modelling software: Siemens Powertrain modelling software: ANSYS Powertrain modelling software: IFPEN Fuel cell development: GCK Mobility & FEV Group Battery modules and packs: GCK Battery Battery immersion cooling system: GCK Battery Battery immersion cooling system: Motul Electric motor development and production: EREM Electric motor active parts development and experimental validation: IFPEN Inverter: Punch Powertrain E-Mobility Engineering | May/June 2024
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