Magnetic gear

Abstract

Embodiments of the present invention relate to magnetic gears comprising first and second moveable members arranged to interact in a magnetically geared manner via a first electrical winding arrangement arranged to generate, at least in part, a first magnetic flux having a first number of pole-pairs, and one or more pole-pieces arranged to modulate the first magnetic flux to interact with a second magnetic flux having a second number of pole-pairs, wherein the first number of pole-pairs is less than the second number of pole-pairs.

1 . A magnetic gear comprising input and output moveable members arranged to interact in a magnetically geared manner and transmit torque therebetween via a first electrical winding arrangement arranged to generate, at least in part, a first magnetic flux having a first number of pole-pairs, and one or more pole-pieces arranged to modulate the first magnetic flux to interact with a second magnetic flux having a second number of pole-pairs, such that asynchronous harmonics of the magnetic field that is produced by each flux-producing member are created which have the same number of poles as the other flux-producing member and so interact, wherein the first number of pole-pairs is less than the second number of pole-pairs. 
     
     
         2 . The magnetic gear as claimed in  claim 1 , wherein the second magnetic flux is generated by a plurality of permanent magnets. 
     
     
         3 . The magnetic gear according to  claim 1 , wherein the first electrical winding arrangement is associated with the input member. 
     
     
         4 . The magnetic gear according to  claim 1 , wherein the plurality of permanent magnets is associated with the second member. 
     
     
         5 . The magnetic gear according to  claim 1 , wherein the plurality of permanent magnets is associated with a stator. 
     
     
         6 . The magnetic gear as claimed in  claim 1 , wherein the second magnetic flux is generated, at least in part, by a second electrical winding arrangement. 
     
     
         7 . The magnetic gear according to  claim 6 , wherein the first electrical winding arrangement is associated with the input member and the second electrical winding arrangement is associated with a stator. 
     
     
         8 . The magnetic gear according to  claim 6 , wherein the first electrical winding arrangement is associated with a stator and the second electrical winding arrangement is associated with one of the input or output members. 
     
     
         9 . The magnetic gear as claimed in  claim 6 , wherein the first and second electrical winding arrangements are associated with the input and output members, respectively. 
     
     
         10 . The magnetic gear as claimed in  claim 1 , wherein the first, or at least one, electrical winding arrangement is arranged to be provided with an electrical current controlled in response to a torque level transmitted by the magnetic gear. 
     
     
         11 . The magnetic gear as claimed in  claim 10 , wherein the electrical current is controlled to maintain a load-angle in a predetermined range. 
     
     
         12 . (canceled) 
     
     
         13 . The magnetic gear as claimed in  claim 10 , wherein the electrical current is DC. 
     
     
         14 . The magnetic gear as claimed in  claim 10 , wherein the electrical current is AC. 
     
     
         15 . (canceled) 
     
     
         16 . The magnetic gear as claimed in  claim 1 , wherein the first magnetic flux is partly generated by one or more permanent magnets. 
     
     
         17 . The magnetic gear as claimed in  claim 16 , wherein the one or more permanent magnets are associated with a moveable member carrying the first electrical winding arrangement. 
     
     
         18 . The magnetic gear as claimed in  claim 1 , wherein the first electrical winding arrangement is formed by a plurality of separately controllable groups of electrical windings, wherein the groups of electrical windings are selectively controlled to vary a gear ratio between the input and output members. 
     
     
         19 . The magnetic gear as claimed in  claim 1 , wherein a first electrical winding arrangement is arranged to form salient poles. 
     
     
         20 . The magnetic gear as claimed in  claim 1  wherein an electrical winding arrangement is arranged to form a distributed winding. 
     
     
         21 . (canceled) 
     
     
         22 . The magnetic gear as claimed in  claim 1 , wherein the pole-pieces are associated with a stator. 
     
     
         23 . The magnetic gear as claimed in  claim 1 , wherein the pole-pieces are associated with a moveable member. 
     
     
         24 . (canceled) 
     
     
         25 . The magnetic gear as claimed in  claim 1 , wherein the input and output members are interposed by a stator having the pole-pieces associated therewith. 
     
     
         26 . The magnetic gear as claimed in  claim 1 , wherein the first electrical winding arrangement is associated with an inner moveable element. 
     
     
         27 . The magnetic gear as claimed in  claim 1 , wherein the plurality of electromagnets is associated with an outer moveable element. 
     
     
         28 . The magnetic gear as claimed in  claim 1  in which the input and output members are rotatable members. 
     
     
         29 . The magnetic gear as claimed in  claim 1  in which the input and output members comprise translatable members. 
     
     
         30 . A magnetic gear system comprising a magnetic gear according to  claim 1  and a controller arranged to provide an electrical current to, at least, the first electrical winding arrangement, wherein the controller is arranged to control the electrical current in response to a torque level transmitted by the magnetic gear. 
     
     
         31 . The magnetic gear system of  claim 30 , wherein the controller is arranged to control the electrical current to maintain a load-angle in a predetermined range. 
     
     
         32 . (canceled) 
     
     
         33 . The magnetic gear system of  claim 30 , wherein the controller is arranged to provide electrical current to first and second groups of electrical windings associated, 5 such that a gear ratio between the moveable members is changed. 
     
     
         34 . A magnetic gear comprising first and second rotatable members arranged to interact in a magnetically geared manner via a plurality of electromagnets associated with the first rotatable member, the plurality of electromagnets being arranged to generate a first magnetic flux having a first number of pole-pairs, and one or more pole-pieces arranged to modulate the first magnetic flux to interact with a second magnetic flux having a second number of pole-pairs generated by a plurality of permanent magnets associated with the second rotatable member, wherein the first number of pole-pairs is less than the second number of pole-pairs. 
     
     
         35 . A magnetic gear comprising first and second rotatable members arranged to interact in a magnetically geared manner via a plurality of electromagnets associated with a stator, the plurality of electromagnets being arranged to generate a first magnetic flux, having a first number of pole-pairs, and one or more pole-pieces associated with the first rotatable member being arranged to modulate the first magnetic flux to interact with a second magnetic flux having a second number of pole-pairs generated by a plurality of permanent magnets associated with the second rotatable member, wherein the first number of pole-pairs is less than the second number of pole-pairs. 
     
     
         36 . A magnetic gear comprising first and second rotatable members arranged to interact in a magnetically geared manner via a plurality of electromagnets and one or more permanent magnets associated with the first rotatable member, the one or more permanent magnets and, selectively, the plurality of electromagnets being arranged to generate a first magnetic flux, having a first number of pole-pairs, one or more pole pieces being arranged to modulate the first magnetic flux to interact with a second magnetic flux, having a second number of pole-pairs, generated by a second plurality of electromagnets associated with a stator, wherein the first number of pole-pairs is less than the second number of pole-pairs. 
     
     
         37 . A magnetic gear comprising first and second rotatable members arranged to interact in a magnetically geared manner via a first plurality of electromagnets associated with the first rotatable member, the plurality of electromagnets being arranged to generate a first magnetic flux having a first number of pole-pairs, and one or more pole-pieces associated with the second rotatable member and arranged to modulate the first magnetic flux to interact with a second magnetic flux having a second number of pole-pairs generated by a plurality of permanent magnets or a second plurality of electromagnets associated with a stator, wherein the first number of pole-pairs is less than the second number of pole-pairs. 
     
     
         38 . A turbine comprising a magnetic gear or magnetic gear system according to  claim 1 . 
     
     
         39 . A wind turbine comprising a magnetic gear or magnetic gear system according to  claim 1 . 
     
     
         40 . A method of controlling a magnetic gear, comprising energising a plurality of electromagnets to generate, at least in part, a first magnetic flux having a first number of pole-pairs, and modulating the first magnetic flux to cause a geared interaction with a second magnetic flux having a second number of pole-pairs, wherein the first number of pole-pairs is less than the second number of pole-pairs. 
     
     
         41 . The method as claimed in  claim 40 , comprising determining the first magnetic flux level according to a level of torque transmitted by the magnetic gear. 
     
     
         42 . The method as claimed in  claim 41 , wherein the magnetic flux level is determined to maintain a load-angle in a predetermined range. 
     
     
         43 . (canceled) 
     
     
         44 . The method according to  claim 40 , wherein the plurality of electromagnets is energised when a level of torque transmitted by the magnetic gears exceeds a predetermined value. 
     
     
         45 . The method as claimed in  claim 40 , wherein one or more electromagnets comprise a spatially distributed multi-phase winding and energizing one or more of the electromagnets by multiphase ac currents that are temporally displaced. 
     
     
         46 . The method as claimed in  claim 40 , comprising selectively energizing one or more electromagnets of the plurality of electromagnets so as to vary a gear ratio between the first and second moveable members. 
     
     
         47 . (canceled) 
     
     
         48 . (canceled)