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%).
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.