Rotary electric motor having controller and power supply integrated therein

#The present invention relates to rotary electric motors, more particularly to motor structure having electrical control and drive elements integrated therein.

#The progressive improvement of electronic systems, such as microcontroller and microprocessor based applications for the control of motors, as well as the availability of improved portable power sources, has made the development of efficient electric motor drives for vehicles, as a viable alternative to combustion engines, a compelling challenge. Electronically controlled pulsed energization of windings of motors offers the prospect of more flexible management of motor characteristics. By control of pulse width, duty cycle, and switched application of a battery source to appropriate stator windings, functional versatility that is virtually indistinguishable from alternating current synchronous motor operation can be achieved. The use of permanent magnets in conjunction with such windings is advantageous in limiting current consumption.

#The above-identified copending related U.S. patent application of Maslov et al., Ser. No. 09/826,422, identifies and addresses the need for an improved motor amenable to simplified manufacture and capable of efficient flexible operating characteristics. In a vehicle drive environment, it is highly desirable to attain smooth operation over a wide speed range, while maintaining a high torque output capability at minimum power consumption. Such a vehicle motor drive should advantageously provide accessibility to the various structural components for replacement of parts at a minimum of inconvenience. The copending related U.S. application incorporates electromagnet poles as isolated magnetically permeable structures configured in an annular ring, relatively thin in the radial direction, to provide advantageous effects. With this arrangement, flux can be concentrated, with virtually no loss or deleterious transformer interference effects in the electromagnet cores, as compared with prior art embodiments. While improvements in torque characteristics and efficiency are attainable with the structure of the identified copending application, further improvements remain desirable.

#The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawing and in which like reference numerals refer to similar elements and in which:

#FIG. 1 is a partial three dimensional perspective view of a motor according to the present invention.

#FIG. 2 is an exploded view of the structural components of the motor of FIG. 1 illustrative of the positional relationship among the various elements.

#The motor of the present invention is suitable for use in driving a vehicle wheel of an automobile, motorcycle, bicycle, or the like. The drawing illustrations thus depict motor structure that can be housed within a vehicle wheel, the stator rigidly mounted to a stationary shaft and surrounded by a rotor for driving the wheel. It should be appreciated, however, that the vehicle context is merely exemplary of a multitude of particular applications in which the motor of the present invention may be employed.

#FIG. 1 is a cutaway drawing of the motor structure, the elements shown in more detail in the exploded view of FIG. 2. Motor 10 comprises annular permanent magnet rotor 20 and annular stator structure 30 separated by a radial air gap. The rotor and stator are configured coaxially about an axis of rotation, which is centered in stationary shaft 36. The stator comprises a plurality of ferromagnetically isolated elements, or stator groups. Core segments 32, made of magnetically permeable material separated from direct contact with each other, have respective winding portions 34 formed on each pole. Seven stator groups are shown, each group comprised of two salient electromagnet poles allocated circumferentially along the air gap. The rotor comprises a plurality of permanent magnets 22, circumferentially distributed about the air gap and affixed to a non-magnetic annular back plate 24, which may be formed of aluminum or other non magnetically permeable material. The back plate is part of the motor housing to which is attached side walls 26.

#The flux distributions produced by the rotor magnets may be enhanced by the provision of a magnetically permeable element, not shown, mounted to the back of the rotor magnets. Sixteen rotor magnets are shown. It is to be understood that the numbers of stator poles and rotor magnets illustrated are merely exemplary, as various ratios can be utilized, depending on desired operational parameters. For example, fewer electromagnets spaced at greater distances may produce different torque and/or speed characteristics. The stator core segments are secured to a rigid skeletal structure 40 that is centrally fixed to the shaft 36. Spine members 42, equal in number to the number of stator groups, extend radially away from the center of structure 40 to U-shaped plates 44. The U-shaped plate sides and the stator core segments contain mating holes by which the stator segments are fixed to the skeletal structure. Each U-shaped plate engages an adjacent pair of stator segments.