On Electronics: Sept. 2013
Magnetic CVT Saves Fuel
Magnomatics’ (magnomatics.com) magnetic continuously variable transmission (mCVT) replaces the epicyclical gear and the motor generator of a traditional hybrid powertrain in a simple concentric package. Depending on the design, the system could also eliminate the engine flywheel and torsional damper. The mCVT allows a variable speed drive to be connected to a fixed speed load, is highly efficient and compact, and requires no cooling or lubrication.
Compared with mechanical power split devices (such as those used in the Toyota Prius), simulations run by Magnomatics engineers show the mCVT would provide somewhere between a 3% and 5% fuel economy improvement.
The mCVT is two rings of permanent magnets with a ring of steel pole pieces in between. These steel pieces act as flux paths from each ring of magnets. This creates harmonics in the fields produced by each ring of magnets and with precise selection of pole numbers, a gear ration is created by coupling the harmonic field.
The device isn’t passive since power flow is always required through the stator, either as a source or sink. Typically, the maximum power required in the control stator is 25% of the power being transferred through the powertrain, Magnomatics says.
The technology is being evaluated by Ford and Volvo Trucks as part of government-funded projects and is also being evaluated by a large Japanese Tier One supplier, the company says.
Melexis (melexis.com) has developed the MLX90366 and MLX90367 to extend the capability and performance of existing Single Edge Nibble Transmission (SENT) protocol devices to fully support position sensing implementations for systems like those used for powertrain and steering applications. The new position sensors provide 12-bit resolution and 10-bit accuracy.
The MLX90366 uses Melexis’ innovative “dual-mold” package, which integrates passive pro-tection components directly into the IC package improving reliability and materials costs, the company says. The MLX90367 is implemented in JEDEC standard SO and TSSOP packages for integration onto conventional PCB assemblies. The sensors support future product progression changes
via ROM/firmware changes.