Permanent magnet biased virtual elliptical motor

A wobble plate motor (10), comprising:

• a wobble plate (12) made of magnetically susceptible material and having a wobble axis (14);
• and
• a stator (16) disposed below the wobble plate and having a stator axis (18), the stator including
• a permanent magnet (102);
• a stator core (104) disposed below the permanent magnet;
• a set of magnetically susceptible pole pieces (106) distributed circumferentially around the stator core;
• a first set of electromagnetic coils (124) disposed circumferentially around the stator core between the stator core and the set of pole pieces;
• and
• a second set of electromagnetic coils (126) disposed circumferentially around the stator core between the stator core and the set of pole pieces;
• wherein each of the first set of electromagnetic coils overlaps circumferentially with each of an adjacent pair of electromagnetic coils of the second set of electromagnetic coils;
• wherein the wobble plate is configured to nutate around the stator with the wobble axis precessing around the stator axis;
• wherein the wobble plate has a mobile point of closest approach (20) with respect to the stator, where the mobile point of closest approach moves around the stator axis as the wobble plate nutates;
• and
• wherein the permanent magnet and the first and second sets of electromagnetic coils are configured to create a magnetic field having a flux density between the stator and the wobble plate with a highest flux density at a mobile location (34) ahead of the mobile point of closest approach in an angular direction around the stator axis.

A method of magnetically driving a wobble plate motor 10, the method comprising:

• providing a stator (16) disposed below a wobble plate (12) and having a stator axis (18), the stator including:
• a permanent magnet (102);
• a stator core (104) disposed below the permanent magnet;
• a set of magnetically susceptible pole pieces (106) distributed circumferentially around the stator core, the pole pieces configured to carry a primary radial magnetic field (220) from the permanent magnet;
• a first set of electromagnetic coils (124) disposed circumferentially around the stator core between the stator core and the set of pole pieces;
• and
• a second set of electromagnetic coils (126) disposed circumferentially around the stator core between the stator core and the set of pole pieces;
• inducing a first current (170) in each of a pair of adjacent electromagnetic coils of the first set of electromagnetic coils, the first current having a minimum current value (420) at a first time (401), a maximum current value (422) at a second time (402), and the minimum current value at a third time (403), with a difference between the third time and the first time being a fraction of a full period of nutation (410) of the wobble plate;
• and
• inducing a second current (172) in each of a pair of adjacent electromagnetic coils of the second set of electromagnetic coils, the second current having the minimum current value at the second time, the maximum current value at the third time, and the minimum current value at a fourth time (404), with a difference between the fourth time and the second time being a fraction of the full period of nutation of the wobble plate;
• wherein one of the pair of adjacent electromagnetic coils of the first set of electromagnetic coils overlaps circumferentially with one of the pair of adjacent electromagnetic coils of the second set of electromagnetic coils and the other of the pair of adjacent electromagnetic coils of the first set of electromagnetic coils overlaps circumferentially with both of the pair of adjacent electromagnetic coils of the second set of electromagnetic coils.