Electronically commutated axial conductor motor

Abstract

An electronic motor with a stator core having a plurality of holes for receiving a plurality of conductors, each conductor comprising a substantially linear body portion extending within the holes of the stator core, and a stator drive member adjacent each end of the stator core, the stator end member adjacent at least one end of the stator core including electronic control circuitry electrically coupled to at least some of the conductors. Also, a method of manufacturing an electronic motor by providing a stator with a plurality of holes having conductors within at least some of the plurality of holes, said conductors each having a substantially linear body portion extending through the stator core, and placing a drive member on each end of the stator core, at least one of the drive members provided with electronic circuitry, where the conductors are electrically coupled to the circuitry in the drive member.

Claims

1. An electronic motor comprising a stator core having a plurality of holes therein and a plurality of conductors comprising a substantially linear body portion extending within at least some of the holes of the stator core, and a stator drive member adjacent first and second ends of the stator core, the stator drive member adjacent at least one of the first and second ends of the stator core comprising electronic control circuitry electrically coupled to at least some of the conductors, wherein the plurality of conductors are each coupled to at least one switch at each end of the substantially linear body portion and the substantially linear body portion of each of the plurality of conductors is substantially straight without a significant change in direction between the switches at each end.

2. The electronic motor of claim 1 wherein the stator core comprises a stack of laminate elements.

3. The electronic motor of claim 1 wherein at least a plurality of the conductors consist of a discrete, substantially linear body.

4. The electronic motor of claim 1 wherein the conductors comprise an insulation on at least a portion thereof.

5. The electronic motor of claim 1 wherein at least one of the stator drive members comprises printed circuitry.

6. The electronic motor of claim 1 wherein at least a plurality of the switches comprising the at least one switch at each end of the conductor are solid-state switches.

7. The electronic motor of claim 6 wherein the solid-state switches are formed of transistors coupled to an integrated circuit board.

8. The electronic motor of claim 7 wherein the integrated circuit board is associated with at least one of the stator drive members.

9. The electronic motor of claim 6 wherein the solid state switches are driven by a microcontroller.

10. The electronic motor of claim 9 wherein the microcontroller provides multiple motor functions, including one or more of a DC connection, a single-phase connection and a 3-phase connection.

11. The electronic motor of claim 6 wherein the solid-state switches are combined in a bidirectional bridge configuration.

12. The electronic motor of claim 1 wherein at least a plurality of the switches comprising the at least one switch at each end of the conductor are semiconductor switches.

13. The electronic motor of claim 1 wherein at least a plurality of the switches comprising the at least one switch at each end of the conductor are formed of transistors installed or fabricated directly onto at least one of the first and second ends of the stator core.

14. The electronic motor of claim 1 wherein each of the plurality of conductors coupled to at least one switch at each end of the conductor form discrete switch circuits.

15. The electronic motor of claim 14 wherein the switch circuits provide commutation to and from a negative and positive DC bus on at least one of the first and second ends of the stator core.

16. The electronic motor of claim 1 wherein each end of each of the plurality of conductors are coupled to three switches.

17. A method of manufacturing an electronic motor comprising the steps of providing a stator core with a plurality of holes having conductors within at least some of the plurality of holes, said conductors each having a substantially linear body portion extending through the stator core, and placing a drive member on each end of the stator core, at least one of the drive members provided with electronic circuitry, where the conductors are electrically coupled to the circuitry in the drive members, further comprising coupling at least one switch to each end of the plurality of substantially linear body portions wherein the substantially linear body of each of the plurality of conductors is substantially straight without a significant change in direction between the switches at each end.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The attached drawings, in which like reference characters represent like parts, are intended to better illustrate a preferred embodiment of the present invention without limiting the invention in any manner whatsoever.

(2) FIG. 1 is an exploded perspective view of an embodiment of the motor of the present invention.

(3) FIG. 2 is a schematic of an embodiment of the motor of the present invention showing the electronics associated with both the upper and lower end members.

(4) FIG. 3 is a cross-sectional view of a stator ring for use in an embodiment of the present invention.

(5) FIG. 4 is an exploded perspective view of an embodiment of the present invention in a linear array.

(6) FIG. 5 is a cross-sectional view of a prior art stator ring used in wound conductor motors.

(7) FIG. 6 is a chart showing data from a stator rewinding manual.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(8) The following description of the preferred embodiment is presented to describe the present invention without limiting the scope of the appended claims in any manner whatsoever.

(9) As shown in FIGS. 1-5, the present claimed invention is directed to an electronic motor comprising a stator assembly or core 2, preferably formed of laminated stack or plate elements 4, having a plurality of holes 6 therein and a plurality of conductors 8 comprising a substantially linear body portion 10 extending within the holes 6 of stator core 2, and a stator drive member 12 adjacent each end of the stator core 4, the stator end member 12 adjacent at least one of the ends of the stator core 4 comprising electronic control circuitry 14.

(10) A power jumper 13 provides an electrical connection between upper and lower stator end members 12 having one or more switches 18 coupled to the conductors 8, and to an output connection, shown in FIG. 1 with an optional DC connection 16a, single phase connection 16b and 3-phase connection 16c.

(11) Although the stator core 2 is preferably formed of a laminated stack of steel elements 4, the conductors 8 can be surrounded by any suitable insulation magnetic core material, either laminated or solid, including but not limited to ferrite or powdered iron compounds.

(12) Similarly, the conductors 8 can be made of any suitable conductor material, including any of a wide variety of metals or similar electrically conductive material. Moreover, the conductor linear body portions 10 can have any suitable length between the upper end member 12a and the lower end member 12b, dependent on the motor size and format for a general or particular application.

(13) The upper and lower end members 12a and 12b can be formed of any suitable material, including but not limited to fiberglass resin or a phenolic, ceramic or similar non-conductive substrate material, and may include apertures in which the conductors 8 extend for connection with the control circuitry 14. The number and pattern of the apertures may be anything suitable for the intended purpose. Alternatively, an electrical connection may be effected between the end members and the conductors by means of a direct pressure contact on conductive circuit traces formed upon the end member.

(14) Most preferably, the control circuitry 14 connected to the conductors 8 provides for multiple motor functions, including one or more of a DC connection, a single-phase connection and a 3-phase connection. Notwithstanding, the nature of the stator core 2 and electronic circuitry 14 associated with the conductors 8 permit virtually any multiple phase and/or multiple pole configurations.

(15) For example, the typical 3-phase induction motor stator 2 shown in FIG. 1 includes the discrete, bidirectional commutation of each conductor 8, with discrete straight conductors 8 replacing windings, allowing for fully automated assembly and production. As described above, the stator core 2 may comprise a laminate stack of annular plates or rings 4, perforated to accept the straight connectors 8, eliminating slots. The conductors 8 may be fed from opposing power busses in the drive or end members 12 via embedded solid state switches, eliminating winding end loops and minimizing wasteful lateral winding currents.

(16) The following simple calculations are intended to explore the stator voltage, current, and the stator conductor size & quantity, required for an Electronically Commutated Axial Conductor Motor (ECACM) to approximately match the performance of a typical wire-wound stator three-phase squirrel-cage induction motor.

(17) The representative commercial motor selected is a 2-HP 208V 3-phase, 2-pole motor manufactured by Baldor. The motor specifications are as follows:

(18) TABLE-US-00001 Catalog Number: 617M Horsepower: 2 Voltage: 208 Hertz: 60 Phase: 3 Full Load Amps: 5.7 A Poles: 2 RPM: 3450 NEMA Frame: 145T

(19) Using the values for a 208 v Delta connection, the full-load current figure of 5.7 A yields a total power rate of 1186 VA per phase leg, for a total of 3,558 VA. A motor operating at full load consumes real power at the rate of 746 W/HP divided by efficiency. Assuming 80% efficiency, the formula yields a real power consumption of (2×746 W)/0.8=1865 W. The power factor of the motor, 1865 W/3558 VA, is therefore about 0.52.

(20) To match the performance of this motor in a similar frame size, we need to match the magnetic flux in the stator. Since this magnetic flux is proportional to the current in the winding multiplied by the number of turns (assuming a stator core of identical reluctance, i.e., the same length, cross-sectional area and material), we need to know the number of turns of wire in the windings. A stator rewinding manual for the motor (part of a pump maintenance manual) gives the data shown in FIG. 6.

(21) The total turns in the example motor is 36×13=468 turns. Every turn of wire represents a bidirectional pass through the stator, so to operate at the same current, the motor requires twice as many conductors, or 936. Alternatively, the current and conductor size may be increased with a proportional decrease in conductor quantity, which is the preferred approach for smaller motors (perhaps less than 5 HP) because the larger conductors offer the rigidity needed for automated assembly.

(22) The example motor uses two parallel strands of No. 19 wire, for a cross-sectional area of (2×1290 cmil) or 0.002 in.sup.2 per turn. Multiplying by 2×468 turns gives a total winding cross-sectional area of 1.87 in.sup.2.

(23) In the above example, the cross-sectional area of the stator is calculated to be about 17.3 in.sup.2, so the example motor has a winding-to-stator area ratio of 11%. No longer limited by the need to use slots, the motor of the present invention allows conductors to be evenly distributed over the cross-section of the stator core 2 as shown in FIG. 3. The conductor-to-stator area ratio is limited instead by conductor separation, semiconductor density at the end ring, and stator laminate structural considerations.

(24) At a proposed ratio of 20%, the present motor conductors 8 have a total available area of 0.20×17.3 in.sup.2, or 3.46 in.sup.2. A convenient starting point for conductor sizing is 16 AWG, because it offers suitable stiffness. Its cross-sectional area is 2580 cmil, almost exactly matching the 0.002 in.sup.2 of the two parallel 19-gauge wires. But at a 20% fill ratio, our 3.46 in.sup.2 permits a total of 1730 conductors, doubling the required number. Alternatively, the wire size may be increased to reduce the conductor count and permit a higher current per conductor (and lower buss voltage).

(25) The foregoing calculations suggest that the goal of at least duplicating the performance of a standard 3-phase induction motor using the present motor is possible in a similar motor frame size. One skilled in the art can evaluate the density and size of transistor commutation elements for the required current capacity for use in a general or particular application.

(26) The improvement is not limited to application in rotating machines. The principals and construction methods are suitable for other geometries, including linear motors and actuators, an example of which is shown in FIG. 4. Here, conductors 8 are arranged in parallel linear stators 2 driven by integrated circuit drive members 12 that are in the form of strips rather than rings. Potential applications include linear motors and actuators, positioning systems, track locomotion and braking, acceleration of projectiles, etc.

(27) The present invention extends to any device or arrangement requiring a moving magnetic field. In fact, the nature of the invention may be simply described as a “direct digital synthesizer” of a moving magnetic field.

(28) The present invention further comprises a method of manufacturing an induction motor comprising the steps of providing a stator core 2 with a plurality of holes 6 having conductors within at least some of the plurality of holes 6, said conductors 8 having a substantially linear body portions 10 extending through the stator 2, placing an end member 12 on each end of the conductors 8, at least one of the end drive members 12 provided with electronic circuitry 14.

(29) In one embodiment, the stator core 2 can be manufactured from a plurality of stack elements 4 forming a laminated core member 2.

(30) In one embodiment, the conductors 8 can be inserted into the holes 6 in the stator core 2 after the stator core 2 is formed.

(31) In one embodiment, at least one end drive member 12 can be provided with electronic circuitry.

(32) Variations, modifications and alterations to the above detailed description will be apparent to those skilled in the art. All such variations, modifications and/or alternatives are intended to fall within the scope of the present invention, limited only by the claims. Any cited patents and/or publications are incorporated by reference.