AutoblogGreen

What Porsche CTO Wolfgang Duerheimer actually says in the first video is that the electric motor in the Cayenne Hybrid's drivetrain can be used at speeds up to 75mph. This does NOT mean the vehicle can sustain that speed using electric power alone, merely that the motor can still deliver some boost assist.

Beyond that vehicle speed the rotor of the permanent-magnet synchronous motor spins too rapidly even when the transmission is in its highest gear. Regular PMSMs have fixed field strengths and therefore near-constant torque across their speed range. However, beyond rated speed, operation is not possible due to excessive mechanical and thermal loads on the device.

Siemens VDO has presented a PMSM with additional coil windings on the rotor that permit changing the remanence of the permanent magnets on the fly. This permits operation of the motor at higher speeds, albeit at reduced torque - rated power is the limiting factor. However, Porsche is not using this technology in its hybrid drivetrain.

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Fast Lane Daily has an exclusive inside look at the LA Auto Show. check out their video with highlights of the Nissan GT-R presented by Karan Singh of StreetFire.
http://www.veoh.com/users/carvideos

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