Low speed discoidal electric motor

Abstract

A low-speed electric motor of lightweight construction with rotor diameter greater than 500 mm, its width of a few cm, without a gearbox, with starting torque being of an order 100 Nm, it makes use of the principle of Coulomb forces. The dimensional arrangement of both the rotor and stator even at high level of torques eliminates flip-flop effect, which is typical for conventional step motors. Rotor consists of rotor disks ( 10 ) with a fixing ring ( 7 ). The carrier ( 1 ) of the permanent magnets ( 2 ) is attached to the fixing ring ( 7 ). The rotor is linked with fixing hub ( 14 ) by means of ball bearings ( 13 ) whose bearing bushings ( 12 ) are mounted with the rotor disks ( 10 ). The stator disk ( 11 ) is attached to the fixing hub ( 14 ). The segment in the shape of circular section made from soft magnetic material ( 3 ), which the coils are slid on, is accommodated in the spokes ( 8 ) fixed by the shank ( 9 ) to the stator disk ( 11 ). Relative position of every coil ( 4 ) relative to the permanent magnet ( 2 ) is monitored by the position indicator ( 5 ). The stator segments ( 3 ), which the coils ( 4 ) are placed on, making up the poles of the motor, are compensated and they are neutral from the point of view of forces F Fe with the resultants of these forces ( 17 ), that are created by a coincidence of the permanent magnets of the rotor ( 2 ) and the segment of the stator ( 3 ) made from soft magnetic material and simultaneously compensated by zero resultant intensity of the magnetic flux ÓH=0 on the poles ( 15 ) of the segments ( 3 ) relative to the permanent magnets of the rotor ( 2 ) in all motor control modes for the reason of gradual connecting the stator coils ( 4 ) to the voltage and thanks to it no parasite forces ( 18 ) are produced bringing about the flip-flop effect and vibrations because the design engineering arrangement satisfies simultaneously the following interrelations: 1. The number and design engineering arrangement of the permanent magnets of the rotor ( 2 ); 2. The number and design engineering arrangement of the stator segments made from soft magnetic material ( 3 ); 3. The number of the motor phases, and 4. The number and position of stator coils ( 4 ) that make up the poles of the motor installed on every segment ( 3 ) depending on the number of motor phases.

1 . Low-speed discoidal electric motor making use of the principle of Coulomb forces is characterised by light engineering structure with rotor diameter greater than 500 mm, width of few cm, without a gearbox, with the starting torque being of an order 100 Nm, where dimensional arrangement of the rotor and stator even at high levels of torque eliminates parasite force producing flip-flop effect that is typical for conventional step motors.  
   
   
       2 . The low-speed electric motor according to the  claim 1)  characterised by the fact that the poles of the stator are composed by active parts of the coils ( 4 ) in the air gap with a constant dimension along the circumference of the motor consisting of the segments of the stator in the shape of circular section made from soft magnetic material ( 3 ) and the surfaces of the permanent magnets of the rotor ( 2 ).  
   
   
       3 . The low-speed motor according to the  claim 1)  characterised by the fact that the segments of the stator in the shape of circular section made from soft magnetic material ( 3 ) on which the coils ( 4 ) are accommodated and that make up the poles of the motor, are from the point of view of forces (F Fe ) with the resultant force ( 17 ) that are produced by the coincidence of the permanent magnets ( 2 ) and the segments of the stator made from soft magnetic material ( 3 ) compensated in such a manner that the conditions specified further are met together, and the aforementioned conditions are as follows: the number of permanent magnets of the rotor ( 2 ) is even number, the external cylindrical surface of the segments of the stator is made from soft magnetic material ( 3 ) and it has constant uniform distance from the surface of every permanent magnet ( 2 ) in every position of the rotor relative to the stator and the number of stator segment made from soft magnetic material ( 3 ) is a co-prime number non-commensurable with the number of the permanent magnets of the rotor ( 2 ) that on the top of that has yet such property consisting in the fact that the nearest higher as well as the nearest lower number must also be co-prime numbers non-commensurable with the number of the permanent magnets of the rotor ( 2 ) and both numbers being higher and lower but by two are the numbers commensurable with the number of the permanent magnets of the rotor ( 2 ).  
   
   
       4 . The low-speed motor according to the  claim 1  characterised by the fact that on the poles ( 15 ) of the segments ( 3 ) the sum of the intensity of the magnetic field ÓH=0 for the reason of gradual connecting the coils of the stator to the voltage so that they do not produce any parasite forces ( 18 ) generating vibrations relative to the permanent magnets of the rotor thanks to the fact that the coils ( 4 ) on the segment ( 3 ) that make up the poles of the electric motor must satisfy the relation conditions, when the number of the coils ( 4 ) on the segment ( 3 )=2× the number of phases of the motor×N (wherein N=integer), and wherein every phase of the motor must be represented on the segment ( 3 ) by equal number of the coils ( 4 ) and the position of the coils ( 4 ) on the segment ( 3 ) must meet a condition for angular distribution on the stator irrespective of the dimensions and the distribution of the stator segments made from soft magnetic material ( 3 ), and wherein the angle of coil fitting for i-th phase=(360/number of rotor permanent magnets)×(coil order+(i−1)/n motor phases ) wherein, i=integer in the interval 1 up to n motor phases  and n motor phases= the number of motor phases.