Control system for a controllable permanent magnet machine

#The invention relates to a control system for a dynamoelectric machine, and more particularly to a control system for adjusting rotor-stator magnetic flux interaction in a dynamoelectric machine of the permanent magnet type.

#U.S. Ser. No. 11/405,743 to Himmelmann, filed 17 Apr. 2006, now U.S. Pat. No. 7,385,332, with which this application has common inventorship and ownership, describes various dynamoelectric machines of the permanent magnet type. Such machines may have rotor magnets that are axially displaceable from a corresponding stator assembly to vary rotor-stator magnetic flux interaction, such as to reduce back electromagnetic force (emf) generation in motor operation at high rotational velocities and thereby improve high-velocity motor torque. Rotor displacement may conveniently be by means of hydraulic actuation driven by machine lubrication oil pressure. In such an instance, it may be necessary to have some means of adjusting such lubrication oil pressure to control rotor magnet displacement.

#For a dynamoelectric machine that has at least one rotor component proximate a stator that is axially displaceable from the stator in response to pressure of lubrication oil delivered to its lubrication system, the invention generally comprises a system for changing axial displacement of each axially displaceable rotor component from the stator to cause a corresponding change in rotor-stator magnetic flux interaction, comprising: a hydraulic pump for generating a flow of lubrication oil; and means for regulating the flow of lubrication oil to the machine to develop a corresponding lubrication oil pressure that controls axial displacement of each axially displaceable rotor component.

#FIG. 1 is a schematic diagram of a machine rotor displacement control system according to a possible embodiment of the invention.

#FIG. 2 is a schematic diagram of a machine rotor displacement control system according to another possible embodiment of the invention.

#FIG. 1 is a schematic diagram of a machine rotor displacement control system 2 according to a possible embodiment of the invention for dynamoelectric machines as described in Himmelmann, which this application incorporates by reference. A dynamoelectric machine 4 has a housing 6, a stator assembly 8 coupled to the housing 6, a drive shaft 10 with journal sections 12 supported by bearings 14 and a rotor assembly 16 coupled to the drive shaft 10 proximate the stator assembly 8. The stator assembly 8 comprises multiple stator poles 18.

#The rotor assembly 16 comprises a rotor yoke 20 coupled to at least one rotor hub 22 by way of at least one hydraulic actuator assembly 24. By way of example only, FIG. 1 shows two rotor hubs 22 so coupled to the rotor yoke 20. Each hydraulic actuator assembly 24 comprises a rotor yoke projection 26 and a rotor hub aperture 28. Each rotor hub 22 also mounts multiple permanent magnets 30 proximate the stator poles 18.

#The drive shaft 10 comprises at least one axial lubrication oil channel 32 that serves as a conduit for lubrication oil within the axial lubrication oil channel 32 to lubricate the bearings 14 by way of multiple radial lubrication oil channels 34. The axial lubrication oil channel 32 also couples to each hydraulic actuator assembly 24 by way of at least one radial yoke channel 36 and at least one axial yoke channel 38. Variance in pressure of lubrication oil within the axial lubrication oil channel 32 will therefore cause the rotor hubs 22 to change their axial displacement from the rotor yoke 20 as represented by arrows 40.