Fault-tolerant redundant electric motors

Abstract

The electric motor assembly includes a rotor, a stator, and first and second electromagnetic windings in first and second distinct sets of a plurality of stator slots operatively configured to be selectively energized to exert torque on the rotor, the first winding including first and second coils in first and second pairs of slots in the first set of slots, the first coil including a first number of turns, the second coil including a second number of turns greater than the first number of turns, and the second winding including third and fourth coils in third and fourth pairs of slots in the second set of slots, the third coil including a third number of turns, and the fourth coil including a fourth number of turns greater than the third number of turns.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to the field of electric motors, and more particularly to an improved electric motor stator assembly. [Background technology]

[0002] A brushless DC motor typically includes a rotor and a stator with electrical windings (typically insulated copper windings) wound around a stator core. The rotor rotates relative to the stator due to magnetic forces generated by energized coils in the stator. The rotor typically consists of a shaft and permanent magnets. When the windings are energized, they create a magnetic field that interacts with the magnetic field of the rotor's permanent magnets to produce torque and subsequent rotation in the rotor. The stator is often cylindrical in shape, and the rotor is positioned within the stator and held in place by end plates and bearings. A radial air gap is provided between the outer surface of the rotor and the inner surface of the stator. The stator is usually stationary and drives the rotor; however, it is possible for the rotor to be stationary and for the stator itself to drive the rotor. Current is introduced into the stator windings so that the stator core material provides a magnetic path for the magnetic field that causes rotation relative to the stator. Summary of the Invention [Problem to be solved by the invention]

[0003] The stator may be formed from a thin layer of high-permeability material consisting of a number of alternating teeth and slots forming the inner circumference of a cylinder, and an outer yoke material holding the teeth in place. Insulated electrical windings are placed in the slots along the teeth to create a magnetic field when current is introduced to the windings. The purpose of the stator coils is to generate magnetic flux that interacts with permanent magnets in the rotor. Thus, a conventional rotary motor includes a generally cylindrical outer stator core, stator windings wound within the stator core, and an inner rotor having permanent magnets that rotate about a central axis relative to the stator core to provide rotary motion by interacting with the stator's magnetic field. [Means for solving the problem]

[0004]

[0023] By way of example only, and not limitation, with parenthetical references to corresponding parts, portions, or surfaces of the disclosed embodiments, there is provided an electric motor assembly (115), comprising: a stator (118); a rotor (119) mounted for operation relative to the stator (118) about a longitudinal axis (120), the rotor (119) comprising at least one permanent magnet (121); and a radial air gap (122) between the stator (118) and the rotor (119), the stator (118) rotating radially about the longitudinal axis (120). The stator (118) comprises a plurality of circumferentially spaced stator teeth (123) oriented radially about the longitudinal axis (120) and extending axially along the longitudinal axis (120) between the plurality of stator teeth (123), the stator (118) comprising a plurality of circumferentially spaced stator slots (1-39) oriented radially about the longitudinal axis (120) and extending axially along the longitudinal axis (120) between the plurality of stator teeth (123), the stator (118) being disposed within a first set (2-19) of the plurality of stator slots (1-39) and operatively configured to be selectively energized to exert torque on the rotor (119). The stator (118) includes a first electromagnetic winding (130) disposed within a second slot set (23-39 / 1) of the plurality of stator slots (1-39) separate from the first slot set (2-19), and a second electromagnetic winding (230) operably configured to be selectively energized to exert a torque on the rotor (119) separate from the first electromagnetic winding (130), and the electric motor assembly (115) includes a first motor drive (160) operably configured to control the first electromagnetic winding (130) and a second motor drive (160) operably configured to drive the second electromagnetic winding (230). and a second motor drive (260) configured to operate to control the first electromagnetic winding (130), wherein the first electromagnetic winding (130) comprises first coils (131, 136, 140, 145) disposed in first slot pairs (2 / 5, 3 / 6, 15 / 18, 16 / 19) within a first slot set (2-19) of the plurality of stator slots (1-39), and second coils (132, 137, 139, 144) disposed in second slot pairs (5 / 8, 6 / 9, 12 / 15, 13 / 16) within the first slot set (2-19) of the plurality of stator slots (1-39);A first coil (131, 136, 140, 145) of the first electromagnetic winding (130) includes a first number of turns (9T, 14T, 14T, 9T) in a first pair of slots (2 / 5, 3 / 6, 15 / 18, 16 / 19) in a first set of slots (2-19) of the plurality of stator slots (1-39), and a second coil (132, 137, 139, 144) of the first electromagnetic winding (130) includes a first number of turns (9T, 14T, 14T, 9T) in a first pair of slots (2 / 5, 3 / 6, 15 / 18, 16 / 19) in a first set of slots (2-19) of the plurality of stator slots (1-39). The second electromagnetic winding (230) includes a second number of turns (19T, 19T, 19T, 19T) greater than 14T, 14T, 9T) in a second pair of slots (5 / 8, 6 / 9, 12 / 15, 13 / 16) in a first set of slots (2-19) of the plurality of stator slots (1-39), and the second electromagnetic winding (230) includes a third coil (231, 236, 240, 245) disposed in a third pair of slots (23 / 26, 24 / 27, 36 / 39, 37 / 1) in a second set of slots (23-39 / 1) of the plurality of stator slots (1-39), and a third coil (231, 236, 240, 245) disposed in a third pair of slots (23 / 26, 24 / 27, 36 / 39, 37 / 1) in a second set of slots (23-39 / 1) of the plurality of stator slots (1-39). and a fourth coil (232, 237, 239, 244) disposed in a fourth pair of slots (26 / 29, 27 / 30, 33 / 36, 34 / 37) in a second set of slots (23-39 / 1) of the plurality of stator slots (1-39), and a third coil (231, 236, 240, 245) of the second electromagnetic winding (230) includes a third number of turns (9T, 14T, 14T, 9T) in a third pair of slots (23 / 26, 24 / 27, 36 / 39, 37 / 1) in a second set of slots (23-39 / 1) of the plurality of stator slots (1-39), and An electric motor assembly (115) is provided in which the coils (232, 237, 239, 244) include fourth numbers of turns (19T, 19T, 19T, 19T) in fourth slot pairs (26 / 29, 27 / 30, 33 / 36, 34 / 37) in the second slot set (23-39 / 1) of the plurality of stator slots (1-39), the fourth numbers of turns being greater than the third numbers of turns (9T, 14T, 14T, 9T) in third slot pairs (23 / 26, 24 / 27, 36 / 39, 37 / 1) in the second slot set (23-39 / 1) of the plurality of stator slots (1-39).

[0005] The first coil (131) of the first electromagnetic winding (130) having a first number of turns (9T) in the first slot pair (2 / 5) in the first slot set (2-19) may be circumferentially arranged between the second coil (132) of the first electromagnetic winding (130) having a second number of turns (19T) in the second slot pair (5 / 8) in the first slot set (2-19) and the third coil (245) of the second electromagnetic winding (230) having a third number of turns (9T) in the third slot pair (37 / 1) in the second slot set (23-39 / 1). The third coil (245) of the second electromagnetic winding (230) having the third number of turns (9T) in the third slot pair (37 / 1) in the second slot set (23-39 / 1) can be circumferentially arranged between the first coil (131) of the first electromagnetic winding (130) having the first number of turns (9T) in the first slot pair (2 / 5) in the first slot set (2-19) and the fourth coil (244) of the second electromagnetic winding (230) having the fourth number of turns (19T) in the fourth slot pair (34 / 37) in the second slot set (23-39 / 1).

[0006] The first number of turns (9T) in the first slot pair (2 / 5) in the first slot set (2-19) can be equal to the third number of turns (9T) in the third slot pair (37 / 1) in the second slot set (23-39 / 1), and the second number of turns (19T) in the second slot pair (5 / 8) in the first slot set (2-19) can be equal to the fourth number of turns (19T) in the fourth slot pair (34 / 37) in the second slot set (23-39 / 1). The first pair of slots (2 / 5) in the first set of slots (2-19) may comprise a first slot (2) and a second slot (5), and the second pair of slots (5 / 8) in the first set of slots (2-19) may comprise a second slot (5) in the first set of slots (2-19) and a third slot (8) in the first set of slots (2-19).

[0007] The first electromagnetic winding (130) can include a first phase (B1), a second phase (A1), and a third phase (C1), and the second electromagnetic winding (230) can include a fourth phase (B2), a fifth phase (A2), and a sixth phase (C2). The first phase (B1) of the first electromagnetic winding (130) can include a first coil (131) in a first pair of slots (2 / 5) in the first set of slots (2-19) and a second coil (132) in a second pair of slots (5 / 8) in the first set of slots (2-19). The fourth phase (B2) of the second electromagnetic winding (230) may include a third coil (231) in a third pair of slots (23 / 26) in the second set of slots (23-39 / 1) and a fourth coil (232) in a fourth pair of slots (26 / 29) in the second set of slots (23-39 / 1). The second phase (A1) of the first electromagnetic winding (130) may include a fifth coil (136) in a fifth pair of slots (3 / 6) in the first set of slots (2-19) and a sixth coil (137) in a sixth pair of slots (6 / 9) in the first set of slots (2-19). The fifth coil (136) of the first electromagnetic winding (130) may include a fifth number of turns (14T) in the fifth slot pair (3 / 6) in the first slot set (2-19), and the sixth coil (137) of the first electromagnetic winding (130) may include a sixth number of turns (19T) in the sixth slot pair (6 / 9) in the first slot set (2-19), which is greater than the fifth number of turns (14T) in the fifth slot pair (3 / 6) in the first slot set (2-19). The fifth phase (A2) of the second electromagnetic winding (230) can include a seventh coil (236) in the seventh slot pair (24 / 27) in the second slot set (23-39 / 1) and an eighth coil (237) in the eighth slot pair (27 / 30) in the second slot set (23-39 / 1).The seventh coil (236) of the second electromagnetic winding (230) may include a seventh number of turns (14T) in the seventh slot pair (24 / 27) in the second slot set (23-39 / 1), and the eighth coil (237) of the second electromagnetic winding (230) may include an eighth number of turns (19T) in the eighth slot pair (27 / 30) in the second slot set (23-39 / 1), which is greater than the seventh number of turns (14T) in the seventh slot pair (24 / 27) in the second slot set (23-39 / 1). The third phase (C1) of the first electromagnetic winding (130) can include a ninth coil (145) in a ninth slot pair (16 / 19) in the first slot set (2-19) and a tenth coil (144) in a tenth slot pair (13 / 17) in the first slot set (2-19). The ninth coil (145) of the first electromagnetic winding (130) may include a ninth number of turns (9T) in the ninth slot pair (16 / 19) in the first slot set (2-19), and the tenth coil (144) of the first electromagnetic winding (130) may include a tenth number of turns (19T) in the tenth slot pair (16 / 19) in the first slot set (2-19) that is greater than the ninth number of turns (9T) in the ninth slot pair (16 / 19) in the first slot set (2-19). The sixth phase (C2) of the second electromagnetic winding (230) may include an eleventh coil (245) in an eleventh slot pair (37 / 1) in the second slot set (23-39 / 1) and a twelfth coil (244) in a twelfth slot pair (34 / 37) in the second slot set (23-39 / 1). The eleventh coil (245) of the second electromagnetic winding (230) may include an eleventh number of turns (9T) in the eleventh slot pair (37 / 1) in the second slot set (23-39 / 1), and the twelfth coil (244) of the second electromagnetic winding (230) may include a twelfth number of turns (19T) in the twelfth slot pair (34 / 37) in the second slot set (23-39 / 1), which is greater than the eleventh number of turns (9T) in the eleventh slot pair (37 / 1) in the second slot set (23-39 / 1).

[0008] The stator (118) may include empty winding slots (20-22) circumferentially disposed between the first electromagnetic winding (130) in a first slot set (2-19) of the plurality of stator slots (1-39) and the second electromagnetic winding (230) in a second slot set (23-39 / 1) of the plurality of stator slots (1-39). The stator (118) may include second empty winding slots circumferentially disposed between the first electromagnetic winding (130) in the first slot set (2-19) of the plurality of stator slots (1-39) and the second electromagnetic winding (230) in the second slot set (23-39 / 1) of the plurality of stator slots (1-39).

[0009] The stator slots of the first slot set (2-19) can be positioned circumferentially adjacent to one another, and the stator slots of the second slot set (23-39 / 1) can be positioned circumferentially adjacent to one another. The first end stator slot (2) of the first slot set (2-19) can be positioned circumferentially adjacent to the second end stator slot (1) of the second slot set (23-39 / 1).

[0010] The first electromagnetic winding (130) may include three or more electrical phases (A1 / B1 / C1), and the current passing through the first electromagnetic winding (130) in a given stator slot (5) of the first slot set (2-19) may not be of the same electrical phase as the current passing through the first electromagnetic winding (130) in the stator slots (4, 6) of the first slot set (2-19) adjacent to the given stator slot (5).

[0011] The stator slots in the first slot set (2-19) may be circumferentially disposed in a first semicircle or first minor arc (125) about the longitudinal axis (120), and the stator slots in the second slot set (23-39 / 1) may be circumferentially disposed in a second semicircle or second minor arc (126) about the longitudinal axis (120) that is separate from the first semicircle or first minor arc (125) about the longitudinal axis (120). The stator slots in the first slot set (2-19) may be circumferentially disposed on a first side of a diametric center plane (124) passing through the longitudinal axis (120), and the stator slots in the second slot set (23-39 / 1) may be circumferentially disposed on a second side of the diametric center plane (124) passing through the longitudinal axis (120).

[0012] The electric motor assembly (115) may include a first power supply (163) connected to the first motor drive (160) and configured to power the first electromagnetic winding (130), and a second power supply (263) connected to the second motor drive (260) and configured to power the second electromagnetic winding (230). The first power supply (163) may include a three-phase AC power source. The second power supply (263) may include a capacitor or a battery. The second motor drive (260) may be configured to operate a common DC bus such that energy from the first power supply (163) is used to charge the second power supply (263) when the second power supply (263) is not fully charged. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a longitudinal cross-sectional view of a first embodiment of an electric motor assembly. FIG. [Figure 2] FIG. 2 is a cross-sectional and partial schematic view of the stator and rotor shown in FIG. [Figure 3] FIG. 3 is a winding distribution diagram of the stator shown in FIG. 2. [Figure 4] FIG. 2 is a schematic diagram of the power drive and control electronics for the electric motor shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0014] First, it should be clearly understood that like reference numerals are intended to identify the same structural elements, portions, or surfaces consistently throughout the several drawings, as such elements, portions, or surfaces may be further described or illustrated by the entire written specification, of which this detailed description is an integral part. Unless otherwise indicated, the drawings (e.g., cross-hatching, arrangement of parts, proportions, extent, etc.) are intended to be read together with the specification and should be considered part of the entire written description of the invention. As used in the following description, the terms "horizontal," "vertical," "left," "right," "upper," and "lower," as well as their adjective and adverbial derivatives (e.g., "horizontally," "rightwardly," "upwardly," etc.), simply refer to the orientation of the depicted structure when the view of a particular drawing is facing the reader. Similarly, the terms "inwardly" and "outwardly" generally refer to the orientation of a surface relative to its axis of elongation or rotation, as appropriate.

[0015] Referring now to the drawings, and more particularly to FIG. 1 thereof, the present disclosure broadly provides a fault-tolerant motor assembly, one embodiment of which is designated 115. As shown, motor 115 generally includes an outer housing 116 supporting a stator 118 and a rotor 119. In this embodiment, motor 115 is a brushless, variable-speed, permanent magnet motor that is current-fed and includes feedback from position sensors 127 and 128 to monitor the angle of common rotor 119 about axis 120 used for closed-loop motion control. Motor 115 has an inner common rotor 119 with permanent magnets 121 and a fixed, non-rotating common stator stack 118 with an independent first winding 130 separated from an independent second winding 230. Rotor 119 includes outer magnets 121 facing radially extending stator teeth 123 of stator 118 across a radial air gap 122. The rotor 119 is configured to selectively rotate about a rotation axis 120 relative to the stator 118 and the housing 116. The stator 118 does not rotate relative to the housing 116. When current is appropriately applied to the windings of the stator 119, a magnetic field is induced. The magnetic field interaction between the stator 118 and the rotor 119 generates a torque that allows the rotor 119 to rotate, and the rotor 119 is connected via a shaft 117 and a mechanical linkage to rotate or linearly drive a movable object. The linkage may include gears, ball screws, or other similar devices. For example, without limitation, the linkage may include a ball screw to convert rotary motion into linear motion and provide a linear stroke. A gear train may be used to provide mechanical advantage to the torque generated by the motor 115, or alternatively, no gears may be used.

[0016] To control the motor 115 during normal operation, the electronic controller 129 selectively distributes power from separate, independent power supplies 163 and 263 to the three-phase windings 130 and 230, respectively, via independent motor drivers 160 and 260, causing a rotating magnetic field to be generated by the corresponding stator windings. The motor 115 includes position sensors 127 and 128 for determining the angular position of the rotor 119. Feedback information provided by sensors 127 and 128 determines the position of the rotor 119, which in turn determines the position of the permanent magnets 121 in the rotor 119. With this knowledge, the motor controller 129 can generate a rotating magnetic field to cause the electric motor 115 to rotate at a desired speed and torque. Based on the angular position feedback of the position sensor 127 received by the controller 172, the drive electronics 160 generates and commutates the stator magnetic field via the first motor winding 130 to vary the speed and direction of the rotor 119. The drive electronics 260 can also generate and commutate a stator magnetic field via the second motor windings 230 to vary the speed and direction of the rotor 119 based on angular position feedback of the position sensor 128 received by the controller 272. Thus, the motor 115 selectively applies torque to the rotor 119 at a speed that varies in one direction about the axis 120 and torque to the rotor 119 at a speed that varies in the opposite direction about the axis 120. The rotor 119 is thereby mounted for movement about the longitudinal axis 120 relative to the stator 118 with a radial air gap 122 between the stator 118 and the rotor 119.

[0017] In the illustrated embodiment, position sensors 127 and 128 are resolvers. However, encoders, linear variable differential transformers ("LVDTs"), or other similar devices can alternatively be used. The position sensors can be any electrical device for measuring position, a derivative of position, or distance from an object, examples of which include encoders, resolvers, linear variable differential transformers, variable resistors, variable capacitors, laser range finders, ultrasonic distance detectors, infrared distance detectors, or other similar devices. Sensorless commutation techniques can also alternatively be used, examples of which include back electromotive force (EMF) observers, salience-based techniques, and other similar approaches.

[0018] As shown in FIGS. 1 and 2 , the stator 118 is a hollow, cylindrical member extending radially inward about a longitudinal axis 120 and including 39 circumferentially spaced stator teeth 123 equally spaced circumferentially about the longitudinal axis 120. The stator teeth 123 also extend axially along the longitudinal axis 120 opposite the length of the rotor 119. The stator teeth 123 define a plurality of circumferentially spaced stator slots 1-39 therebetween. The stator slots 1-39 are oriented radially about the longitudinal axis 120 and are equally spaced circumferentially about the axis 120 between the stator teeth 123. The stator slots 1-39 also extend axially along the longitudinal axis 120 between the stator teeth 123. Although a 39 slot motor is shown and described in this embodiment, motors having different numbers of slots can alternatively be used, including but not limited to motors having an even number of slots.

[0019] As shown in Figures 2-3, stator 118 has two electrically separated and insulated windings 130 and 230. Winding 130 is coiled within slots 2-19 and includes three phases A1, B1, and C1 with five coils in each phase. Phase A1 includes coils 136, 137, 138, 139, and 140. Phase B1 includes coils 131, 132, 133, 134, and 135. Phase C1 includes coils 141, 142, 143, 144, and 145. For each phase, the coil slot start, coil orientation, and number of turns are also shown in Figure 3.

[0020] As shown, phase A1 is coiled in slots 3, 6, 9, 12, 15, and 18. Coil 136 in paired slots 3 and 6 has 14 turns. Coil 137 in paired slots 6 and 9 has 19 turns. Coil 138 in paired slots 9 and 12 has 19 turns. Coil 139 in paired slots 12 and 15 has 19 turns. Coil 140 in paired slots 15 and 18 has 14 turns.

[0021] Phase B1 is coiled in slots 2, 5, 8, 11, 14, and 17. Coil 131 in paired slots 2 and 5 has 9 turns. Coil 132 in paired slots 5 and 8 has 19 turns. Coil 133 in paired slots 8 and 11 has 19 turns. Coil 134 in paired slots 11 and 14 has 19 turns. Coil 135 in paired slots 14 and 17 has 19 turns.

[0022] Phase C1 is coiled in slots 4, 7, 10, 13, 16, and 19. Coil 141 in paired slots 4 and 7 has 19 turns. Coil 142 in paired slots 7 and 10 has 19 turns. Coil 143 in paired slots 10 and 13 has 19 turns. Coil 144 in paired slots 13 and 16 has 19 turns. Coil 145 in paired slots 16 and 19 has 9 turns.

[0023] As shown, winding 230 is coiled in slots 22-39 and 1. Winding 230 includes three phases, A2, B2, and C2, with five coils in each phase. Phase A2 includes coils 236, 237, 238, 239, and 240. Phase B2 includes coils 231, 232, 233, 234, and 235. Phase C2 includes coils 241, 242, 243, 244, and 245. The coil slot start, coil direction, and number of turns for each phase are also shown in FIG. 3.

[0024] Phase A2 is coiled in slots 24, 27, 30, 33, 36, and 39. Coil 236 in paired slots 24 and 27 has 14 turns. Coil 237 in paired slots 27 and 30 has 19 turns. Coil 238 in paired slots 30 and 33 has 19 turns. Coil 239 in paired slots 33 and 36 has 19 turns. Coil 240 in paired slots 36 and 39 has 14 turns.

[0025] Phase B2 is coiled in slots 23, 26, 29, 32, 35, and 38. Coil 231 in paired slots 23 and 26 has 9 turns. Coil 232 in paired slots 26 and 29 has 19 turns. Coil 233 in paired slots 29 and 32 has 19 turns. Coil 234 in paired slots 32 and 35 has 19 turns. Coil 235 in paired slots 35 and 38 has 19 turns.

[0026] Phase C2 is coiled in slots 25, 28, 31, 34, 37, and 1. Coil 241 in paired slots 25 and 28 has 19 turns. Coil 242 in paired slots 28 and 31 has 19 turns. Coil 243 in paired slots 31 and 34 has 19 turns. Coil 244 in paired slots 34 and 37 has 19 turns. Coil 245 in paired slots 37 and 1 has 9 turns.

[0027] Thus, electromagnetic winding 130 is disposed within a first set of stator slots 1-39, slot 2-19, and is operatively configured to be selectively energized to exert torque on rotor 119. Electromagnetic winding 230 is disposed within a second set of stator slots 1-39, slot 23-39 / 1, that is physically separated from first set of slots 2-19. Although motor 115 has a single common laminated stator stack, windings 130 and 230 do not share any of slots 1-39 of stator 118. Electromagnetic windings 130 and 230 are operatively configured to be selectively energized to exert torque on rotor 119 independently of one another.

[0028] As shown, the stator slots in the first slot set 2-19 are oriented circumferentially in a semicircle or minor arc 125 about the longitudinal axis 120, and the stator slots in the second slot set 23-39 and 1 are oriented circumferentially in a semicircle or minor arc 126 separated from the semicircle 125 about the longitudinal axis 120. The stator slots in the first slot set 2-19 are circumferentially disposed on a first side of a diametric center plane 124 passing through the longitudinal axis 120, and the stator slots in the second slot set 23-39 and 1 are circumferentially disposed on a second side of the diametric center plane 124 passing through the longitudinal axis 120.

[0029] With respect to slot set 2-19 of winding 130, as shown, the number of turns through slot 2 of slot set 2-19, which is closest to the diametrical center plane 124 separating winding 130 from winding 230 at one end of winding 130, is fewer than the number of turns through any of slots 3-18. Similarly, the number of turns through slot 19 of slot set 2-19, which is closest to the diametrical center plane 124 separating winding 130 from winding 230 at the second end of winding 130, is also fewer than the number of turns through any of slots 3-18, and at 9 turns, is equal to the number of turns through slot 2. Moving to the penultimate end slot of slot set 2-19 of winding 130, the number of turns through slot 3, which is second to the diametrical center plane 124 separating winding 130 from winding 230 at the first end of winding 130, is fewer than the number of turns through any of slots 4-17. Similarly, the number of turns through slot 18, which is second adjacent to diametrical center plane 124 separating winding 130 from winding 230 at the second end of winding 130, is also fewer than the number of turns through any of slots 4-17, and at 14 turns, is equal to the number of turns through slot 3. Moving to the next step circumferentially away from diametrical center plane 124 separating winding 130 from winding 230, the number of turns through slot 4, which is third adjacent to diametrical center plane 124 separating winding 130 from winding 230 at the first end of winding 130, is also fewer than the number of turns through any of slots 5-16. Similarly, the number of turns through slot 17, which is third adjacent to diametrical center plane 124 separating winding 130 from winding 230 at the second end of winding 130, is also fewer than the number of turns through any of slots 5-16, and at 19 turns, is equal to the number of turns through slot 4. Moving to the next step circumferentially away from diametrical center plane 124 separating winding 130 from winding 230, the number of turns through slot 5, which is fourth adjacent to diametrical center plane 124 separating winding 130 from winding 230 at a first end of winding 130, is less than the number of turns through any of slots 6-15. Similarly, the number of turns through slot 16, which is fourth adjacent to diametrical center plane 124 separating winding 130 from winding 230 at a second end of winding 130, is also less than the number of turns through any of slots 6-15, and at 28 turns, is equal to the number of turns through slot 5.Moving to the next step circumferentially away from diametrical center plane 124 separating winding 130 from winding 230, slot 6, which is fifth adjacent to diametrical center plane 124 separating winding 130 from winding 230 at a first end of winding 130, has fewer turns than any of slots 7-14. Similarly, slot 15, which is fifth adjacent to diametrical center plane 124 separating winding 130 from winding 230 at a second end of winding 130, has fewer turns than any of slots 7-14, with 33 turns equaling the number of turns in slot 6. The remaining slots 7-14 each contain 38 turns.

[0030] With respect to slot sets 23-39 and 1 of winding 230, as shown, the number of turns through slot 1 of slot set 23-39 and 1 that is closest to diametrical center plane 124 separating winding 230 from winding 130 at one end of winding 230 is fewer than the number of turns through any of slots 24-39. Similarly, the number of turns through slot 23 of slot set 23-39 and 1 that is closest to diametrical center plane 124 separating winding 230 from winding 130 at a second end of winding 230 is also fewer than the number of turns through any of slots 24-39, and at 9 turns, is equal to the number of turns through slot 1. Moving to the penultimate slot of slot sets 23-39 and 1 of winding 230, the number of turns through slot 39 that is second closest to diametrical center plane 124 separating winding 230 from winding 130 at a first end of winding 230 is fewer than the number of turns through any of slots 25-38. Similarly, the number of turns through slot 24 second adjacent to diametrical center plane 124 separating winding 230 from winding 130 at the second end of winding 230 is also fewer than the number of turns through any of slots 25-38 and, at 14 turns, is equal to the number of turns through slot 39. Moving to the next step circumferentially away from diametrical center plane 124 separating winding 230 from winding 130, the number of turns through slot 38 third adjacent to diametrical center plane 124 separating winding 230 from winding 130 at the first end of winding 230 is also fewer than the number of turns through any of slots 26-37. Similarly, the number of turns through slot 25 third adjacent to diametrical center plane 124 separating winding 230 from winding 130 at the second end of winding 230 is also fewer than the number of turns through any of slots 26-37 and, at 19 turns, is equal to the number of turns through slot 38. Moving to the next step circumferentially away from diametrical center plane 124 separating winding 230 from winding 130, the number of turns through slot 37, which is fourth adjacent to diametrical center plane 124 separating winding 230 from winding 130 at a first end of winding 230, is less than the number of turns through any of slots 27-36. Similarly, the number of turns through slot 26, which is fourth adjacent to diametrical center plane 124 separating winding 230 from winding 130 at a second end of winding 230, is also less than the number of turns through any of slots 27-36, and at 28 turns, is equal to the number of turns through slot 37.Moving to the next step circumferentially away from diametrical center plane 124 separating winding 230 from winding 130, slot 36, which is fifth adjacent to diametrical center plane 124 separating winding 230 from winding 130 at a first end of winding 230, has fewer turns than any of slots 28-35. Similarly, slot 27, which is fifth adjacent to diametrical center plane 124 separating winding 230 from winding 130 at a second end of winding 230, has fewer turns than any of slots 28-35, with 33 turns equaling the number of turns in slot 36. The remaining slots 28-35 each contain 38 turns.

[0031] Thus, the number of turns in adjacent slots 1 and 2 on either side of center plane 124 separating winding 230 from winding 130 is reduced. Similarly, the number of turns in slots 19 and 23 on either side of center plane 124 separating winding 230 from winding 130 is reduced. And, in this embodiment, slots 20, 21, and 22 are empty and do not contain coil windings, as shown. Because the total number of slots is odd, and thus in this embodiment center plane 124 extends through slot 21, the number of turns in adjacent slots 20 and 22 on either side of center plane 124 separating winding 230 from winding 130 is reduced to zero.

[0032] As shown, in this embodiment, the reduction in coil turns is gradually decreased in slots 6, 5, 4, 3, and 2 closest to center plane 124 at one end of winding 130, gradually decreased in slots 36, 37, 38, 39, and 1 closest to center plane 124 at one end of winding 230, gradually decreased in slots 15, 16, 17, 18, 19, and 20 closest to center plane 124 at the second end of winding 130, and gradually decreased in slots 27, 26, 25, 24, 23, and 22 closest to center plane 124 at the second end of winding 230. This reduced number of slot turns where windings 130 and 230 are closest circumferentially electrically isolates windings 130 and 230 from each other. Empty slots 20, 21, and 22 located circumferentially between windings 130 and 230 further help to electrically insulate windings 130 and 230 from one another.

[0033] While windings 130 and 230 are shown in this embodiment as each having three phases, such windings may alternatively have more or fewer phases than three. Also, the number of phases for windings 130 and 230 may differ from one another. The number of stator slots may vary, the number of coils and turns in each of the separate windings may vary and may differ from one another, and the amount of reduction in turns circumferentially approaching separation plane 124 and the rate of such reduction may also vary and may differ between windings. For example, as shown by slots 20, 21, and 22 in the embodiment shown in Figure 2, in addition to the adjacent slots on each side of center plane 124 separating the first end of winding 130 from the first end of winding 230 being empty, the adjacent slots on each side of center plane 124 separating the second end of winding 130 from the second end of winding 230 may also be empty and contain no coil windings to further help physically and electrically isolate or separate winding 130 and winding 230 from one another. Although motor 115 is shown as having two separate and separated windings 130 and 230, three or more separate and separated windings may alternatively be used, with additional diametric center planes separating such additional windings.

[0034] 4 , motor drive 160 is configured and operable to control electromagnetic windings 130 of stator 118, and motor drive 260 is configured and operable to independently control electromagnetic windings 230 of stator 118. Motor drive 160 includes power drive electronics 161 and control electronics 162 and is operable to control pulse width modulation (PWM) of windings 130 to power electric motor 115 and generate and commutate the stator magnetic field to vary the speed and direction of electric motor 115 utilizing angular position feedback from motor position sensor 127.

[0035] Power drive electronics 161 controls the flow of power to winding 130 and converts power from power supply 163 into currents that drive winding 130 on phases A1, B1, and C1. Power drive electronics 161 receives power from power supply 163 through input filter 164. In one embodiment, input filter 164 has common-mode and differential-mode filter stages and is operable to reduce high-frequency electronic noise and ensure power supply 163 sees a stable current draw. Filter 164 can also be used to ensure the power supply complies with government regulations and agency standards. Input filter 164 is in electrical communication with inrush regulator 165, which limits the current during this period to protect the electronic circuitry. In one embodiment, inrush regulator 165 can include one or more thermistors and a transformer switching relay. Inrush regulator 165 is in electrical communication with three-phase bridge 166. Three-phase bridge 166 is an inverter operable to convert direct current to alternating current via active switching devices (e.g., IGBTs). The switching elements are electrically connected to the windings 130 and PWM of the windings 130 generates torque on the rotor 119 .

[0036] Regenerative energy circuit 167 and DC link capacitor 168 are arranged in parallel with input filter 164 and three-phase bridge 166. When the current to winding 130 is zero and electric motor 115 experiences a back electromotive force (EMF) higher than the output voltage of motor drive 160, current is steered to motor drive 160 and regenerative energy circuit 167 is operable to recover or dissipate such energy. The recovered energy is returned to DC link capacitor 168. DC link capacitor 168 is operable to reduce ripple in the DC voltage input to three-phase bridge 166.

[0037] Voltage sensor 169 and current sensor 170 provide feedback signals to control electronics 162. The PWM signal is adjusted as a function of the feedback signals from voltage sensor 169 and current sensor 170. In this embodiment, power drive electronics 161 also includes a gate driver 171 in electrical communication with control electronics 162 and three-phase bridge 166. Gate driver 171 is an interface between control electronics 162 and three-phase bridge 166 and generates the high current input to the switching elements.

[0038] Control electronics 162 communicates with drive electronics 161 and includes controller 172. Controller 172 is a digital device having output lines that are logical functions of its input lines; examples of which include a microprocessor, microcontroller, field programmable gate array, programmable logic device, application-specific integrated circuit, or other similar device. Controller 172 includes a data sampling and storage mechanism for receiving and storing sensed data, and data storage for storing operating parameters and sensed data logs. Controller 172 is configured to perform various computer-implemented functions, such as executing method steps, calculations, and the like, and storing associated data, as disclosed herein. To communicate with the various sensors, a sensor interface can convert signals transmitted from the sensors into signals that can be understood and processed by processor 172. Sensors can be coupled to the sensor interface via wired connections. In other embodiments, they can be coupled to the sensor interface via wireless connections. During active operation of electric motor 115, controller 172 provides PWM signals to three-phase bridge 166 to generate desired drive current signals at each terminal of winding 130. Controller 172 receives external motor control commands via command interface 173 and includes inputs for receiving output signals from voltage sensor 169, current sensor 170, and motor position sensor 127. The memory of controller 172 stores values ​​for several operating variables, including power supply thresholds.

[0039] Control electronics 162 includes voltage / current sensor excitation and signal conditioning circuitry 174 and motor position sensor excitation and signal conditioning circuitry 175. Conditioning circuits 174 and 175 convert and amplify received signals into a form compatible with the controller.

[0040] As also shown in FIG. 4 , similar to motor drive 160, motor drive 260 includes power drive electronics 261 and control electronics 262 and is operable to control pulse width modulation (PWM) of windings 230 to power electric motor 115 and generate and commutate the stator magnetic field to vary the speed and direction of electric motor 115 utilizing angular position feedback from motor position sensor 128.

[0041] Power drive electronics 261 controls the flow of power to winding 230 and converts power from power supply 263 into current that drives winding 230 on phases A2, B2, and C2. Power drive electronics 261 receives power from power supply 263 through input filter 264. In one embodiment, input filter 264 has common-mode and differential-mode filter stages and is operable to reduce high-frequency electronic noise and ensure power supply 263 sees a stable current draw. Filter 264 can also be used to ensure the power supply complies with government regulations and agency standards. Input filter 264 is in electrical communication with inrush regulator 265, which limits the current during this period to protect the electronic circuitry. In one embodiment, inrush regulator 265 can include one or more thermistors and a transformer switching relay. Inrush regulator 265 is in electrical communication with three-phase bridge 266. Three-phase bridge 266 is an inverter operable to convert direct current to alternating current via active switching devices (e.g., IGBTs). The switching elements are electrically connected to the windings 230 and PWM of the windings 230 generates torque on the rotor 119 .

[0042] Regenerative energy circuit 267 and DC link capacitor 268 are arranged in parallel with input filter 264 and three-phase bridge 266. When the current to winding 230 is zero and electric motor 115 experiences a back electromotive force (EMF) higher than the output voltage of motor drive 260, current is steered to motor drive 260 and regenerative energy circuit 267 is operable to recover or dissipate braking energy. The recovered energy is returned to DC link capacitor 268. DC link capacitor 268 is operable to reduce ripple in the DC voltage input to three-phase bridge 266.

[0043] Voltage sensor 269 and current sensor 270 provide feedback signals to control electronics 262. The PWM signal is adjusted as a function of the feedback signals from voltage sensor 269 and current sensor 270. In this embodiment, power drive electronics 261 also includes a gate driver 271 in electrical communication with control electronics 262 and three-phase bridge 266. Gate driver 271 is an interface between control electronics 262 and three-phase bridge 266 and generates the high current input to the switching elements.

[0044] Control electronics 262 communicates with drive electronics 261 and includes controller 272. Controller 272 is a digital device having output lines that are logical functions of its input lines; examples of which include a microprocessor, microcontroller, field programmable gate array, programmable logic device, application-specific integrated circuit, or other similar device. Controller 272 includes a data sampling and storage mechanism for receiving and storing sensed data, and data storage for storing operating parameters and sensed data logs. Controller 272 is configured to perform various computer-implemented functions, such as executing method steps, calculations, and the like, and storing associated data, as disclosed herein. To communicate with the various sensors, a sensor interface enables signals transmitted from the sensors to be translated into signals that can be understood and processed by processor 272. Sensors can be coupled to the sensor interface via wired connections. In other embodiments, they can be coupled to the sensor interface via wireless connections. During active operation of electric motor 115, controller 272 provides PWM signals to three-phase bridge 266 to generate desired drive current signals at each terminal of winding 230. Controller 272 receives external motor control commands via command interface 273 and includes inputs for receiving output signals from voltage sensor 269, current sensor 270, and motor position sensor 128. The memory of controller 272 stores values ​​for several operating variables, including power supply thresholds.

[0045] Power supply 163 can comprise a three-phase AC power source. Power supply 263 can also comprise a three-phase AC power source. Alternatively, without limitation, one or both power sources can comprise a capacitor or a battery. One of the power sources may comprise a battery, and the other power source may be configured to operate a common DC bus such that energy from such source is used to charge the battery power source when it is not fully charged.

[0046] Control electronics 262 includes voltage / current sensor excitation and signal conditioning circuitry 274 and motor position sensor excitation and signal conditioning circuitry 275. Conditioning circuits 274 and 275 convert and amplify the signals they receive into a format compatible with the controller.

[0047] In this embodiment, motor 115 has the ability to operate even if either winding 130 or winding 230 fails, or if either motor drive 160 or motor drive 260 fails. While the current design uses a single stator and rotor, one winding can continue to be driven and the motor can operate even if the other winding fails. In this embodiment, motor 115 can operate normally utilizing both windings 130 and 230 and all six motor phases A1, B1, C1, A2, B2, and C2. A motor winding or phase failure terminates operation of the failed motor winding, and motor 115 operates as a three-phase motor via the other independent winding. Similarly, if a motor drive fails, operation of the failed motor drive terminates, and motor 115 operates as a three-phase motor via the other independent motor drive.

[0048] The electric motor system 115 offers many advantages. For example, the motor 115 is doubly redundant and fault-tolerant, so that failure of a single element does not prevent operation of the motor. In this embodiment, it takes the failure of at least two independent windings to stop the motor from operating. Fault tolerance is provided by the reduced rotor length, common set of magnets, and reduced complexity of the stator assembly. The motor's fault tolerance is scalable, so that, for example, quadruple redundancy can be provided. Cross-coupling between the motor's dual windings is negligible. Motor performance is equivalent to the sum of two completely independent, synchronized torque motors.

[0049] The present disclosure is intended to be susceptible to many changes and modifications. Thus, while an improved form of electric motor assembly has been shown and described, and numerous alternatives have been discussed, those skilled in the art will readily appreciate that various additional changes and modifications can be made without departing from the scope of the invention, as defined and distinguished by the following claims.

Claims

1. 1. An electric motor assembly comprising: A stator; a rotor mounted for movement about a longitudinal axis relative to the stator, the rotor comprising at least one permanent magnet; and a radial gap between the stator and the rotor; the stator comprising a plurality of circumferentially spaced stator teeth oriented radially about and extending axially along the longitudinal axis; the stator including a plurality of circumferentially spaced stator slots oriented radially about the longitudinal axis and extending axially along the longitudinal axis between the plurality of stator teeth; the stator comprising a first electromagnetic winding disposed within a first set of the plurality of stator slots and operatively configured to be selectively energized to exert a torque on the rotor; the stator includes a second electromagnetic winding disposed within a second set of the plurality of stator slots, separate from the first set of slots, the second electromagnetic winding operatively configured to be selectively energized to exert torque on the rotor separate from the first electromagnetic winding; the electric motor assembly includes a first motor drive operatively configured to control the first electromagnetic winding; a second motor driver configured to operate to control the second electromagnetic winding; the first electromagnetic winding comprises a first coil wound in a first slot and a second slot in the first set of the plurality of stator slots, and a second coil wound in a third slot and a fourth slot in the first set of the plurality of stator slots; the first coil of the first electromagnetic winding includes a first number of turns in the first slot and a second slot in the first slot set of the plurality of stator slots; the second coil of the first electromagnetic winding includes a second number of turns in the third and fourth slots in the first set of the plurality of stator slots that is greater than the first number of turns in the first and second slots in the first set of the plurality of stator slots; the second electromagnetic winding includes a third coil wound in a fifth slot and a sixth slot in the second set of the plurality of stator slots and a fourth coil wound in a seventh slot and an eighth slot in the second set of the plurality of stator slots; the third coil of the second electromagnetic winding includes a third number of turns in the fifth slot and a sixth slot in the second set of the plurality of stator slots; the fourth coil of the second electromagnetic winding includes a fourth number of turns in the seventh and eighth slots in the second slot set of the plurality of stator slots that is greater than the third number of turns in the fifth and sixth slots in the second slot set of the plurality of stator slots.

2. 2. The electric motor assembly of claim 1, wherein the first coil of the first electromagnetic winding having the first number of turns in the first and second slots in the first set of slots is circumferentially disposed between the second coil of the first electromagnetic winding having the second number of turns in the third and fourth slots in the first set of slots and the third coil of the second electromagnetic winding having the third number of turns in the fifth and sixth slots in the second set of slots.

3. 3. The electric motor assembly of claim 2, wherein the third coil of the second electromagnetic winding having the third number of turns in the fifth and sixth slots in the second slot set is circumferentially disposed between the first coil of the first electromagnetic winding having the first number of turns in the first and second slots in the first slot set and the fourth coil of the second electromagnetic winding having the fourth number of turns in the seventh and eighth slots in the second slot set.

4. 2. The electric motor assembly of claim 1, wherein the first number of turns in the first and second slots in the first slot set is equal to the third number of turns in the fifth and sixth slots in the second slot set, and the second number of turns in the third and fourth slots in the first slot set is equal to the fourth number of turns in the seventh and eighth slots in the second slot set.

5. An electric motor assembly as described in claim 1, wherein the second slot and the third slot are the same slot.

6. 2. The electric motor assembly of claim 1, wherein the first electromagnetic winding includes a first phase, a second phase, and a third phase, and the second electromagnetic winding includes a fourth phase, a fifth phase, and a sixth phase.

7. 7. The electric motor assembly of claim 6, wherein the first phase of the first electromagnetic winding includes the first coil in the first slot and the second slot in the first set of slots and the second coil in the third slot and the fourth slot in the first set of slots.

8. 8. The electric motor assembly of claim 7, wherein the fourth phase of the second electromagnetic winding includes the third coil in the fifth and sixth slots in the second set of slots and the fourth coil in the seventh and eighth slots in the second set of slots.

9. 9. The electric motor assembly of claim 8, wherein the second phase of the first electromagnetic winding includes a fifth coil in ninth and tenth slots in the first set of slots and a sixth coil in eleventh and twelfth slots in the first set of slots.

10. 10. The electric motor assembly of claim 9, wherein the fifth coil of the first electromagnetic winding includes a fifth number of turns in the ninth and tenth slots in the first set of slots, and the sixth coil of the first electromagnetic winding includes a sixth number of turns in the eleventh and twelfth slots in the first set of slots, the sixth number of turns being greater than the fifth number of turns in the ninth and tenth slots in the first set of slots.

11. 11. The electric motor assembly of claim 10, wherein the fifth phase of the second electromagnetic winding includes a seventh coil in thirteenth and fourteenth slots in the second set of slots and an eighth coil in fifteenth and sixteenth slots in the second set of slots.

12. 12. The electric motor assembly of claim 11, wherein the seventh coil of the second electromagnetic winding includes seven turns in the thirteenth and fourteenth slots in the second set of slots, and the eighth coil of the second electromagnetic winding includes eight turns in the fifteenth and sixteenth slots in the second set of slots, the eighth turns being greater than the seventh turns in the thirteenth and fourteenth slots in the second set of slots.

13. 13. The electric motor assembly of claim 12, wherein the third phase of the first electromagnetic winding includes a ninth coil in seventeenth and eighteenth slots in the first set of slots and a tenth coil in nineteenth and twentieth slots in the first set of slots.

14. 14. The electric motor assembly of claim 13, wherein the ninth coil of the first electromagnetic winding includes ninth turns in the seventeenth and eighteenth slots in the first set of slots, and the tenth coil of the first electromagnetic winding includes tenth turns in the nineteenth and twentieth slots in the first set of slots that are greater than the ninth turns in the seventeenth and eighteenth slots in the first set of slots.

15. 15. The electric motor assembly of claim 14, wherein the sixth phase of the second electromagnetic winding includes an eleventh coil in twenty-first and twenty-second slots in the second set of slots and a twelfth coil in twenty-third and twenty-fourth slots in the second set of slots.

16. 16. The electric motor assembly of claim 15, wherein the eleventh coil of the second electromagnetic winding includes eleven turns in the twenty-first and twenty-second slots in the second set of slots, and the twelfth coil of the second electromagnetic winding includes twelfth turns in the twenty-third and twenty-fourth slots in the second set of slots, the twelfth turns being greater than the eleventh turns in the twenty-first and twenty-second slots in the second set of slots.

17. 2. The electric motor assembly of claim 1, wherein the stator includes empty winding slots circumferentially disposed between the first electromagnetic winding in the first set of the plurality of stator slots and the second electromagnetic winding in the second set of the plurality of stator slots.

18. 2. The electric motor assembly of claim 1, wherein the stator slots of the first slot set are positioned circumferentially adjacent one another and the stator slots of the second slot set are positioned circumferentially adjacent one another.

19. 19. The electric motor assembly of claim 18, wherein a first end stator slot of the first slot set is disposed circumferentially adjacent to a second end stator slot of the second slot set.

20. 2. The electric motor assembly of claim 1, wherein the first electromagnetic winding includes three or more electrical phases, and wherein a current passing through the first electromagnetic winding in a given stator slot of the first slot set is not the same electrical phase as a current passing through the first electromagnetic winding in a stator slot of the first slot set adjacent to the given stator slot.

21. 2. The electric motor assembly of claim 1, wherein the stator slots in the first slot set are circumferentially arranged in a first semicircle or first short arc about the longitudinal axis and the stator slots in the second slot set are circumferentially arranged in a second semicircle or second short arc about the longitudinal axis that is separate from the first semicircle or first short arc about the longitudinal axis.

22. 22. The electric motor assembly of claim 21, wherein the stator slots in the first slot set are circumferentially disposed on a first side of a diametric center plane passing through the longitudinal axis, and the stator slots in the second slot set are circumferentially disposed on a second side of the diametric center plane passing through the longitudinal axis.

23. 10. The electric motor assembly of claim 1, comprising: a first power supply connected to the first motor drive and configured to power the first electromagnetic winding; and a second power supply connected to the second motor drive and configured to power the second electromagnetic winding.

24. 24. The electric motor assembly of claim 23, wherein the first power source comprises a three-phase AC power source.

25. 25. The electric motor assembly of claim 24, wherein the second power source comprises a capacitor or a battery.

26. 26. The electric motor assembly of claim 25, wherein the second motor drive is configured to operate a common DC bus such that energy from the first power source is used to charge the second power source when the second power source is not fully charged.

Images