Magnetic Gears
Pseudo Direct Drive PDD
Pseudo Direct Drive

5kNm PDD

Electrical machine with fully integrated magnetic gear offering unrivalled torque density

Magnomatics’ patented Pseudo Direct Drive (PDD®) offers a significant advance over conventional permanent magnet motor/generator technology, achieving a step-change in continuous torque density compared to that of equivalently cooled PM machines while maintaining very high efficiency.

This dramatic increase in torque density allows the motor to directly drive many loads where conventionally a motor and gearbox combination would be employed.  Ideal application will have high continuous torque at relatively low speed.

It is highly suitable for applications ranging from aerospace actuation, marine propulsion drives through to direct drive utility scale wind turbines and rail traction systems.


Marine PDD

PDD Key Benefits

  • Eliminates gearbox
  • Very high efficiency (>97%)
  • High reliability
  • Low maintenance
  • Low cooling requirements
  • Inherent torque overload protection
  • Low NVH
  • Large airgaps enable high shock ratings
  • Standard power electronic inverter/converter
  • Low Cogging Torque (<0.2% of rated torque)
  • Significantly smaller and lighter than direct drive equivalents
  • High power factor (can be tailored for field weakening applications)
  • In-built torsional compliance reduces drivetrain pulsations


PDD Explained

The PDD combines a magnetic gear with a standard wound stator.  The outer arrays of magnets are fixed to the internal bore of the stator and the magnetic fields generated by the windings are used to drive the internal rotor.  The torque produced by this rotor is then geared up in the magnetic gear and transmitted out via the steel pole pieces.  This results in an extremely compact, highly torque dense machine.  The natural elasticity resulting from the magnetic gear means that the output torque has extremely low levels of ripple (<0.3%).

See Video


Applicability Map

The applicability map can be used to decide whether PDD technology is suitable for your application.  See whether your application lies within the red area on the chart.