24 advent of the eFantom. That peak 400 kW is a setting programmed into the eVCU. The motor is physically capable of delivering more than that, but the boat needs completely different torque curves to those experienced in a car. For instance, when going from zero in automotive platforms, one typically needs to generate full torque all at once to overcome tyre friction, but doing this in a boat would be ultimately useless, because one would just create cavitation at the propeller. Hence, both the 400 kW peak and 170 kW continuous maximum are set for safe handling of the boat. The e-motor is a permanent magnet synchronous machine, configured with an inrunner rotor and external radial stator, with the latter integrating liquid cooling channels. The stator and rotor are taken directly from the motor to be used as the core of the next-gen Macan Turbo. Initially, the team wanted to take the whole motor, housing included. But, in the car, the motor is intended to have an integrated e-axle, including transmission parts, and those latter components are superfluous to the boat’s requirements. A different transmission is used for the 850’s stern drive, which has been designed to closely fit the packaging constraints and performance characteristics of the e-motor (and, in any case, the Macan Turbo’s e-axle wouldn’t fit in the boat!). Fortunately, developing the new housing was a straightforward process. The Porsche team studied the housing of the Macan and the Taycan, the latter lacking an integrated axle, and it used the same bearing and sealing concepts as used in those cars to avoid the cost and delays of coming up with something completely new. Although there was a risk of the bearing being oversized, it was deemed a preferable risk to the alternative prospect of the bearing being too small and thus breaking after 100 hours of operation. The inverter is a silicon carbide (SiC)-based unit, developed for the nextgen Macan powertrain, and the first to be used by Porsche. SiC MOSFETs were chosen to minimise switching losses and maximise switching speeds, compared with conventional, silicon insulated-gate bipolar transistors (IGBTs). It can supply 900 A, theoretically more than 500 kW, The e-motor runs at 170 kW maximum continuous power and runs to a stern drive via a shaft with an elastomeric claw clutch The 800 V pack’s 204s2p architecture enables the use of a HV gate to split it into two 400 V systems that can safely recharge from 400 V charging stations without needing a HV booster March/April 2024 | E-Mobility Engineering Dossier | Frauscher x Porsche 850 Fantom Air
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