Method and system for sensing position of component in electric drive unit

Abstract

An electric drive unit includes a housing and a rotor rotatably supported in the housing. The rotor includes a rotor shaft defining a rotor axis and a plurality of rotor laminations fixedly mounted to the shaft. The plurality of rotor laminations support a plurality of magnetic poles, and a hydraulic unit connected to the plurality of rotor laminations. The hydraulic unit has a magnetic shunt selectively movable relative to the plurality of poles. The position sensing system is operable to detect a rotational speed of the rotor and a position of the magnetic shunt relative to the plurality of poles. The position sensing system includes a rotor shaft position trigger coupled for rotation with the rotor shaft, and a magnetic shunt position trigger supported by the hydraulic unit.

Description

Technical Field

[0001] The present invention relates to the field of vehicles, and more particularly, to a method and system for sensing the position of a component in an electric drive unit. Background Art

[0002] The electric drive unit includes an electric motor having a rotor that rotates within a stator that supports stator windings. The rotor supports magnetic poles that generate a magnetic field when rotating within the stator windings. Electric motors such as variable geometry permanent magnet (PM) electric motors typically include a magnetic shunt mounted in the rotor near the magnetic poles. The magnetic shunt is designed to mechanically weaken the magnetic field generated by the electric motor and, in doing so, reduce high speed back electromotive force (EMF).

[0003] The position of the magnetic shunt relative to the magnetic poles is varied in real time to change the peak magnetic flux. In the first speed region, typically below base speed, the magnetic shunt is positioned so as not to bridge the magnetic poles. At higher speeds, the magnetic shunt can be repositioned to bridge the magnetic poles, thereby weakening the magnetic flux. Field weakening is controlled by adjusting the position of the magnetic shunt relative to the magnetic poles.

[0004] Controlling the position of a magnetic shunt relative to a magnetic pole requires two sensors, one to detect the position of the magnetic shunt and the other to detect the position of the magnetic pole. The need for multiple sensors increases the required packaging space, as well as the overall complexity of the motor and associated flux control. It is therefore desirable to provide a system for sensing the position of components in an electric motor that relies on fewer sensors in order to reduce the required packaging space, reduce complexity, and reduce and / or eliminate potential points of failure. Summary of the invention

[0005] According to a non-limiting example, an electric drive unit includes a housing having an inner surface, a stator fixedly supported in the housing, and a rotor rotatably supported in the housing. The rotor includes a rotor shaft defining a rotor axis and a plurality of rotor laminations fixedly mounted to the shaft. The plurality of rotor laminations support a plurality of magnetic poles, and a hydraulic unit connected to the plurality of rotor laminations. The hydraulic unit has a magnetic shunt that is selectively movable relative to the plurality of magnetic poles. A position sensing system is operable to detect a rotational speed of the rotor and a position of the magnetic shunt relative to the plurality of magnetic poles. The position sensing system includes a rotor shaft position trigger coupled to rotate with the rotor shaft, a magnetic shunt position trigger supported by the hydraulic unit, a first inductive sensor mounted to the housing and aligned with the rotor shaft position trigger, and a second inductive sensor mounted to the housing and aligned with the magnetic shunt position trigger.

[0006] In addition to one or more features described herein, the inner surface of the housing includes a first axial end surface, a second axial end surface, and an annular inner surface extending between the first axial end surface and the second axial end surface, and the first inductive sensor is mounted to the first axial end surface.

[0007] In addition to one or more features described herein, a second inductive sensor is mounted to the first axial end surface adjacent to the first inductive sensor.

[0008] In addition to one or more features described herein, the first inductive sensor is spaced apart from the rotor shaft position trigger by a first axial gap.

[0009] In addition to one or more features described herein, the second inductive sensor is spaced apart from the magnetic shunt position trigger by a second axial gap.

[0010] In addition to one or more features described herein, the first inductive sensor is spaced a first radial distance from the rotor axis and the second inductive sensor is spaced a second radial distance from the rotor axis, the second radial distance being greater than the first radial distance.

[0011] In addition to one or more features described herein, the first inductive sensor is spaced 180° from the second inductive sensor relative to the rotor axis.

[0012] In addition to one or more features described herein, the controller is operably connected to the first inductive sensor and the second inductive sensor.

[0013] In addition to one or more features described herein, an electronic circuit board is mounted to the first axial end face and connected to the controller, and the first and second inductive sensors are mounted to and operably connected to the electronic circuit board.

[0014] In addition to one or more features described herein, the inner surface of the housing includes a first axial end face, a second axial end face, and an annular inner surface extending between the first axial end face and the second axial end face, and the first inductive sensor and the second inductive sensor are mounted to the annular inner surface and are operable to detect a rotor shaft position trigger and a magnetic shunt position trigger passing through a radially extending gap.

[0015] According to a non-limiting example, a vehicle includes a vehicle body, a rechargeable energy storage system supported by a battery, and an electric drive unit supported in the vehicle body and electrically connected to the rechargeable energy storage system. The electric drive unit includes a housing having an inner surface, a stator fixedly supported in the housing, and a rotor rotatably supported in the housing. The rotor includes a rotor shaft defining a rotor axis and a plurality of rotor laminations fixedly mounted to the shaft. The plurality of rotor laminations support a plurality of magnetic poles, and a hydraulic unit connected to the plurality of rotor laminations. The hydraulic unit has a magnetic shunt that can be selectively moved relative to the plurality of magnetic poles. A position sensing system is operable to detect a rotational speed of the rotor and a position of the magnetic shunt relative to the plurality of magnetic poles. The position sensing system includes a rotor shaft position trigger coupled to rotate with the rotor shaft, a magnetic shunt position trigger supported by the hydraulic unit, a first inductive sensor mounted to the housing and aligned with the rotor shaft position trigger, and a second inductive sensor mounted to the housing and aligned with the magnetic shunt position trigger.

[0016] In addition to one or more features described herein, the inner surface of the housing includes a first axial end surface, a second axial end surface, and an annular inner surface extending between the first axial end surface and the second axial end surface, and the first inductive sensor is mounted to the first axial end surface.

[0017] In addition to one or more features described herein, a second inductive sensor is mounted to the first axial end surface adjacent to the first inductive sensor.

[0018] In addition to one or more features described herein, the first inductive sensor is spaced apart from the rotor shaft position trigger by a first axial gap.

[0019] In addition to one or more features described herein, the second inductive sensor is spaced apart from the magnetic shunt position trigger by a second axial gap.

[0020] In addition to one or more features described herein, the first inductive sensor is spaced a first radial distance from the rotor axis and the second inductive sensor is spaced a second radial distance from the rotor axis, the second radial distance being greater than the first radial distance.

[0021] In addition to one or more features described herein, the first inductive sensor is spaced 180° from the second inductive sensor relative to the rotor axis.

[0022] In addition to one or more features described herein, the controller is operably connected to the first inductive sensor and the second inductive sensor.

[0023] In addition to one or more features described herein, an electronic circuit board is mounted to the first axial end face and connected to the controller, and the first and second inductive sensors are mounted to and operably connected to the electronic circuit board.

[0024] In addition to one or more features described herein, the inner surface of the housing includes a first axial end face, a second axial end face, and an annular inner surface extending between the first axial end face and the second axial end face, and the first inductive sensor and the second inductive sensor are mounted to the annular inner surface and are operable to detect a rotor shaft position trigger and a magnetic shunt position trigger passing through a radially extending gap.

[0025] The above features and advantages and other features and advantages of the present disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, advantages and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings, in which:

[0027] Figure 1 is a left side view of a vehicle including a variable geometry electric motor according to a non-limiting example;

[0028] Figure 2 is a cross-sectional side view of a variable geometry electric motor including a rotor position sensing system according to a non-limiting example;

[0029] Figure 3 According to non-limiting examples Figure 2 An exploded view of the rotor;

[0030] Figure 4 According to non-limiting examples Figure 1 A perspective view of a rotor of a variable geometry electric motor and an inductive sensor of a rotor position sensing system;

[0031] Figure 5 According to non-limiting examples Figure 1 A partially exploded perspective view of a rotor and a variable geometry electric motor;

[0032] Figure 6 is a block diagram illustrating a control system for a rotor position sensing system according to a non-limiting example; and

[0033] Figure 7 is a cross-sectional side view of a variable geometry electric motor including a rotor position sensing system according to another non-limiting example. DETAILED DESCRIPTION

[0034] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or use. It should be understood that in all figures, corresponding reference numerals represent the same or corresponding parts and features. As used herein, the term module refers to a processing circuit, which may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated or group) and memory that executes one or more software or firmware programs, a combinational logic circuit and / or other suitable components that provide the described functions.

[0035] According to a non-limiting example, the vehicle Figure 1 1. The vehicle 10 is generally indicated at 10. The vehicle 10 includes a body 12 supported on a plurality of wheels 16. The body 12 partially defines a passenger compartment 20 having a seat 23 located behind an instrument panel 26. A steering controller 30 is disposed between the seat 23 and the instrument panel 26. The steering controller 30 is operated to control the orientation of selected wheels of the plurality of wheels 16. The vehicle 10 includes an electric drive unit 34 that provides power to one or more of the plurality of wheels 16.

[0036] A rechargeable energy storage system (RESS) or battery assembly 38 is disposed in the vehicle body 12 and provides power to the electric drive unit 34. In other arrangements, a fuel cell may be used to provide power to the electric drive unit 34. In this regard, it should be understood that the location of the electric drive unit 34 and the battery assembly 38 may vary. In a non-limiting example, the electric drive unit 34 takes the form of a variable geometry electric motor 40. In this regard, it should be understood that a variable geometry electric drive unit describes an electric motor that includes a movable magnetic member that can be moved to change the magnetic flux path between a rotor and a stator.

[0037] Now refer to Figure 2 and Figure 3 A variable geometry electric motor 40 is described according to a non-limiting example. The variable geometry electric motor 40 includes a housing 48 including an outer surface 51 and an inner surface 53. The housing 48 includes a first axial end wall 56, a second axial end wall 58, and an intermediate wall 60 extending between and connected to the first axial end wall 56 and the second axial end wall 58. The inner surface 53 includes a first axial end surface 63 associated with the first axial end wall 56, a second axial end surface 65 associated with the second axial end wall 58, and an annular inner surface 67 associated with the intermediate wall 60.

[0038] The first axial end wall 56 includes an opening 70 that receives a rotor shaft 72 that extends through the housing 48. The rotor shaft 72 defines a rotor axis "A" that extends through the opening 70. The rotor shaft 72 is supported at the first axial end wall 56 by a first bearing 74. The rotor shaft 72 is supported at the second axial end wall 58 by a second bearing 76. The rotor shaft 72 supports a rotor 80 formed of a plurality of rotor laminations 82. The rotor laminations 82 support a plurality of magnetic poles 84 ( Figure 3 ).

[0039] Likewise Figure 3 As shown, the rotor shaft 72 also supports a hydraulic unit 86 having a drive system 88. The hydraulic unit 86 includes a plurality of magnetic shunts 90. The drive system 88 includes a plurality of drive gears 92 that engage drive gears 94. As will be described in more detail herein, the drive system 88 selectively operates the drive gears 92 to rotate the drive gears 94 to adjust the relative position of the magnetic shunts 90 supported by the hydraulic unit 86 relative to the magnetic poles 84 supported by the plurality of rotor laminations 82.

[0040] In a non-limiting example, a stator 96 is mounted on the annular inner surface 67. The stator 96 extends around the rotor 80 and includes a plurality of stator laminations 98 supporting stator windings 100. Electrical energy provided by the RESS 38 passes through the stator windings 100 to induce a magnetic field around the rotor 80. The magnetic field interacts with the magnetic poles 84 supported in the rotor laminations 82, causing the rotor 80 to rotate and transmit drive energy to selected wheels of the plurality of wheels 16. In a non-limiting example, the drive system 88 is selectively activated to adjust the relative positions of the magnetic shunts 90 and the magnetic poles 84 so as to control the back electromotive force (EMF) of the variable geometry electric motor 40 to more efficiently and reliably transmit energy to selected wheels of the plurality of wheels 16.

[0041] exist Figure 3 , 4 and 5, and continue with reference to the non-limiting examples shown in Figure 2 , the variable geometry electric motor 40 includes a position sensing system 104 operable to detect the rotational speed of the rotor 80 and determine the relative positions of the magnetic poles 84 and the magnetic shunt 90. The position sensing system 104 includes a rotor shaft position trigger 108 operably coupled to rotate with the rotor shaft 72. The rotor shaft position trigger 108 is mounted on a central hub 111 connected to the rotor shaft 72. The rotor shaft position trigger 108 also includes a plurality of rotor position trigger elements 114 protruding radially outward from the central hub 111.

[0042] The position sensing system 104 also includes a magnetic shunt position trigger 116 that is operably coupled to rotate with the hydraulic unit 86. The magnetic shunt position trigger 116 includes a plurality of magnetic shunt position trigger elements 120. Each of the plurality of rotor position trigger elements 114 and the plurality of magnetic shunt trigger elements 116 includes a structure capable of inducing an inductive response in an inductive sensor. At this point, it should be understood that although disclosed in conjunction with a variable geometry electric motor, the position sensing system 104 may be used in other forms of electric motors where position sensing of motor components would be useful.

[0043] In a non-limiting example, the position sensing system 104 includes a first inductive sensor 129 shown mounted to the first axial end face 63 of the first axial end wall 56 of the housing 48 and a second inductive sensor 132 mounted to the first axial end face 63 of the first axial end wall 56 of the housing 48. In a non-limiting example, the first inductive sensor 129 and the second inductive sensor 132 are coupled to a circuit board 134 mounted on the first axial end face 63 of the first axial end wall 56. Of course, it should be understood that the first inductive sensor 129 and the second inductive sensor 132 can be mounted to different circuit boards, or directly mounted to the first axial end face 63 and connected to the circuit board. In addition, it should be understood that Figure 4 and Figure 5 The description of the first inductive sensor 129 and the second inductive sensor 132 in FIG. 8 is for illustration purposes only. The first inductive sensor 129 and the second inductive sensor 132 should not be construed as being mounted to the rotor 80 .

[0044] refer to Figure 6 And continue to refer to Figure 2 , 3 4, the electronic circuit board 134 is connected to a controller 140, which has a central processing unit (CPU) 142, a speed monitoring module 144, a position monitoring module 146, and an adjustment module 148. The controller 140 can send a signal to the drive system 88 based on the rotational speed of the rotor 80 to adjust the position of the magnetic shunt 90 relative to the magnetic pole 84. In other words, the relative position of the magnetic shunt 90 and the magnetic pole 84 changes in real time to change the peak magnetic flux generated by the variable geometry electric motor 40.

[0045] Below base speed, magnetic shunt 90 will be positioned not to bridge poles 84. At higher speeds, drive system 88 will operate drive gear 92 to move magnetic shunt 90 so as to bridge poles 84, thereby weakening the magnetic flux. The amount of field weakening can be adjusted based on the relative position of magnetic shunt 90 and poles 84. At this time, although it is shown as sensing rotor speed and magnetic shunt position across the axial gap ( Figure 2 ).like Figure 7As shown, sensing may occur at the radial gap. The rotor 80 may include a rotor shaft position trigger 200 that projects axially outward from the hydraulic unit 86. First and second inductive sensors 208 and 210 may be disposed in the annular inner surface 67.

[0046] The terms "one" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced items. The term "or" means "and / or", unless the context clearly indicates otherwise. References to "an aspect" throughout the specification mean that a particular element (e.g., feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in any suitable manner in various aspects.

[0047] When an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0048] Unless otherwise indicated herein, all test standards are the most recent standards in effect as of the filing date of the present application or, if priority is claimed, the filing date of the earliest priority application in which the test standards appear.

[0049] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0050] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from the scope thereof. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the disclosure without departing from the essential scope of the disclosure. Therefore, it is intended that the disclosure is not limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. An electric drive unit, comprising: a housing having an inner surface; A stator fixedly supported in the housing; a rotor rotatably supported in the housing, the rotor comprising a rotor shaft defining a rotor axis, a plurality of rotor laminations fixedly mounted to the shaft, the plurality of rotor laminations supporting a plurality of magnetic poles, and a hydraulic unit connected to the plurality of rotor laminations, the hydraulic unit having a magnetic shunt selectively movable relative to the plurality of magnetic poles; as well as A position sensing system operable to detect a rotational speed of a rotor and a position of a magnetic shunt relative to a plurality of magnetic poles, the position sensing system comprising: a rotor shaft position trigger coupled for rotation with the rotor shaft; A magnetic shunt position trigger supported by a hydraulic unit; a first inductive sensor mounted on the housing and aligned with the rotor shaft position trigger; and A second inductive sensor is mounted on the housing and aligned with the magnetic shunt position trigger.

2. The electric drive unit according to claim 1, wherein: The inner surface of the housing includes a first axial end surface, a second axial end surface, and an annular inner surface extending between the first axial end surface and the second axial end surface, and the first inductive sensor is mounted on the first axial end surface.

3. The electric drive unit according to claim 2, wherein: The second inductive sensor is mounted on the first axial end surface adjacent to the first inductive sensor.

4. The electric drive unit according to claim 3, wherein: The first inductive sensor is spaced apart from the rotor shaft position trigger by a first axial gap.

5. The electric drive unit according to claim 4, wherein: The second inductive sensor is spaced apart from the magnetic shunt position trigger by a second axial gap.

6. The electric drive unit according to claim 4, wherein: The first inductive sensor is spaced a first radial distance from the rotor axis, and the second inductive sensor is spaced a second radial distance from the rotor axis, the second radial distance being greater than the first radial distance.

7. The electric drive unit according to claim 4, wherein: The first inductive sensor is spaced 180° from the second inductive sensor relative to the rotor axis.

8. The electric drive unit according to claim 2 further includes a controller operably connected to the first inductive sensor and the second inductive sensor, and an electronic circuit board mounted to the first axial end surface and connected to the controller, the first inductive sensor and the second inductive sensor being mounted to the electronic circuit board and operably connected thereto.

9. The electric drive unit according to claim 1, wherein: The inner surface of the housing includes a first axial end face, a second axial end face, and an annular inner surface extending between the first axial end face and the second axial end face. The first inductive sensor and the second inductive sensor are mounted on the annular inner surface and are operable to detect the rotor shaft position trigger and the magnetic shunt position trigger passing through the radially extending gap.

10. A vehicle comprising: Car body; a rechargeable energy storage system supported by batteries; as well as An electric drive unit as claimed in claim 1, supported in a vehicle body and electrically connected to a rechargeable energy storage system.

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