High efficiency permanent magnet machine

An electric machine, comprising:

• a rotor, the rotor further including:
• a plurality of rotor sheets affixed to one another using a thermal insulating adhesive;
• having a cylindrical shape and a central axis;
• an axial bore adapted to receive a shaft;
• an outer circumference adapted to receive a plurality of permanent magnets comprising of permanent magnet material, wherein each permanent magnet has a magnetic flux density between 70 and 95 percent of a residual magnetic flux density of the permanent magnet material;
• a stator, the stator further including:
• a plurality of stator sheets affixed to one another using a thermal insulating adhesive;
• having a cylindrical shape and a longitudinal axis;
• an outer circumference;
• a plurality of teeth disposed in an equidistant angular relationship, each tooth projecting inwardly toward the longitudinal axis, the teeth creating a discontinuous inner circumference configured to accept the rotor within the stator such that the longitudinal axis of stator is aligned with the central axis of the rotor and the rotor is rotatable within the inner circumference of the stator;
• a stator slot of predetermined shape and size disposed between each tooth and adapted to receive a predetermined number of strands of conducting material to form an electrical winding around at least one tooth;
• the stator teeth each having a uniform width being between 60 and 80 percent of a slot pitch;
• a current density ranging between 3 and 8 Amp/mm2;
• a torque angle between 2 and 10 degrees;
• and
• an air gap between the outer circumference of the rotor and the inner circumference of the stator when the rotor is disposed within the stator.

An electric machine, comprising:

• a rotor, the rotor further including:
• a plurality of rotor sheets affixed to one another using a thermal insulating adhesive;
• having a cylindrical shape and a central axis;
• an axial bore adapted to receive a shaft;
• an outer circumference adapted to receive a plurality of permanent magnets comprising of permanent magnet material, wherein each permanent magnet has a magnetic flux density between 70 and 95 percent of a residual magnetic flux density of the permanent magnet material;
• a stator, the stator further including:
• a plurality of stator sheets affixed to one another using a thermal insulating adhesive;
• having a cylindrical shape and a longitudinal axis;
• an outer circumference;
• a plurality of teeth disposed in an equidistant angular relationship, each tooth projecting inwardly toward the longitudinal axis, the teeth creating a discontinuous inner circumference configured to accept the rotor within the stator such that the longitudinal axis of stator is aligned with the central axis of the rotor and the rotor is rotatable within the inner circumference of the stator;
• a stator slot of predetermined shape and size disposed between each tooth and adapted to receive a predetermined number of strands of conducting material to form an electrical winding around each tooth;
• a three phase electrical winding scheme where each phase has two groups and each group includes two coils connected in series;
• the strands of conducting material having a cross-sectional related to current density based on
• J
• =
• 4
• 
• I
• π
• 
• 
• d
• 2
• and a low current density (J) ranging between 3 and 8 Amp/mm2;
• a predetermined number of poles, whereby the number of poles is directly proportional to the electrical frequency of the electric machine and inversely proportional to a number of required coil windings;
• the rotor having between 8 and 16 poles when the intended rotational speed of the rotor is less than 3000 rpm;
• the rotor having 2 to 12 poles when the intended rotational speed of the rotor is greater than 6000 rpm;
• a torque angle between 2 and 10 degrees;
• an air gap between the outer circumference of the rotor and the inner circumference of the stator when the rotor is disposed within the stator, the air gap being inversely proportional to the torque angle based on
• g
• ^
• total
• =
• 4
• π
• 
• μ
• 0
• B
• R
• 
• sin
• 
• 
• δ
• 
• N
• ^
• a
• P
• 
• 1.5
• 
• 2
• 
• I
• A
• ,
• rated
• ,
• where ĝtotal is the air gap and δ is the torque angle;
• each of the permanent magnets has a thickness proportional to the air gap such that geffBmR+μ0HmRlm=0, where geff is an effective distance of the air gap and lm is the thickness of each of the permanent magnets;
• a housing enclosing the stator and rotor, wherein the housing includes a passive cooling mechanism;
• a sensorless field oriented control, where a rotor angle is estimated by a sliding mode observer, the sliding mode observer module containing a first order low-pass filter for back electromotive force estimation;
• and
• a control module configured to automatically calculate a phase lag compensation value based on rotational speed of the rotor and is applied to feedback increasing accuracy of the field oriented control.