Common mode noise cancellation electric motor system

Abstract

An electric motor configuration includes a dual output multi-level inverter. The inverter includes first and second sets of alternating current (AC) phase outputs. The first set of AC phase outputs provides a current, each phase output in the first set of AC phase outputs corresponds to one phase output in the second set of AC phase outputs, and each phase output in the first set of AC phase outputs is offset by 180 degrees from a respective phase output in the second set of phase outputs. The electric motor includes first and second sets of antiparallel motor windings. The first set of motor windings is connected to the first set of AC phase outputs and the second set of motor windings is connected to the second set of AC phase outputs. The electric motor includes a mechanical rotary output.

Description

Technical Field

[0001] The present disclosure relates to electric motor configurations and, more particularly, to electric motor systems utilizing a dual output multi-phase inverter to drive a single electric motor. Background Art

[0002] Electric and hybrid vehicles utilize stored electrical energy to drive the rotation of an electric motor, and the rotation from the motor is provided to the vehicle's mechanical system. In most cases, the stored electrical energy is provided in the form of direct current (DC), and the electric motor requires alternating current (AC) to operate properly. In this case, an inverter is used to convert the DC power output from the energy storage device into an AC power output that can be utilized by the electric motor. The power characteristics of the AC power output are typically controlled by the switching rate within the inverter, and the switching rate is in turn controlled by the motor controller according to known feedback control principles. The switching rate of the switches within the inverter is related to the amount of common-mode noise within the motor drive system, and the faster the switching, the greater the common-mode noise. Excessive common-mode noise can interfere with the operation of the motor, resulting in reduced efficiency or suboptimal operation.

[0003] As inverter technology advances, the maximum switching rate of the inverter increases, resulting in a corresponding increase in potential common-mode noise within the electric motor system. Therefore, it is desirable to provide a vehicle motor system that can have a high switching rate within the inverter and reduce common-mode noise. Summary of the invention

[0004] In an exemplary embodiment, an electric motor configuration includes: a dual-output multi-level inverter, which includes a first set of alternating current (AC) phase outputs and a second set of multi-phase AC phase outputs, wherein the first set of AC phase outputs provides current, each phase output in the first set of AC phase outputs corresponds to a phase output in the second set of AC phase outputs, and wherein each phase output in the first set of AC phase outputs is offset by 180 degrees from a corresponding phase output in the second set of phase outputs; and an electric motor, which includes a first set of motor windings and a second set of motor windings configured to be anti-parallel to the first set of motor windings, the first set of motor windings being connected to the first set of AC phase outputs, the second set of motor windings being connected to the second set of AC phase outputs, and wherein the electric motor includes a mechanical rotation output.

[0005] In addition to one or more features described herein, the dual output multilevel inverter is a high speed switching inverter.

[0006] In addition to one or more features described herein, the dual output multilevel inverter is a GaN switch based inverter.

[0007] In addition to one or more features described herein, the electric motor includes a plurality of winding slots corresponding to each phase of the electric motor, and wherein each winding slot includes a winding from the first set of motor windings and a winding from the second set of motor windings.

[0008] In addition to one or more features described herein, windings of the first and second sets of motor windings from at least a subset of the plurality of winding slots are arranged in radial proximity.

[0009] In addition to one or more features described herein, windings of the first set of motor windings and windings of the second set of motor windings from at least a subset of the plurality of winding slots are arranged circumferentially adjacent.

[0010] In addition to one or more features described herein, windings of the first and second sets of motor windings from at least a subset of the plurality of winding slots are arranged in radial proximity.

[0011] In addition to one or more features described herein, an electrical insulating sheet is disposed between adjacent portions of the first set of windings and the second set of windings.

[0012] In addition to one or more features described herein, the first set of motor windings includes a first neutral node, the second set of motor windings includes a second neutral node, and wherein the first neutral node is connected to the second neutral node such that the first and second neutral nodes are electrically connected in at least one operating mode.

[0013] In addition to one or more features described herein, the first and second neutral nodes are connected by an electronically controlled switch.

[0014] In addition to one or more features described herein, the first neutral node is electrically floating relative to the second neutral node.

[0015] In addition to one or more features described herein, the motor controller is communicatively coupled to a plurality of current sensors, each current sensor of the plurality of current sensors being configured to detect a net current magnitude output through a pair of corresponding phases.

[0016] In addition to one or more features described herein, the plurality of current sensors includes N-1 Hall effect current sensors, where N is a total number of phases of the electric motor.

[0017] In another exemplary embodiment, a vehicle includes an electrical energy storage system connected to a first electric motor through a first dual-output multilevel inverter, wherein the electrical energy storage system provides direct current (DC) power to the first dual-output multilevel inverter; the first dual-output multilevel inverter includes a first set of alternating current (AC) phase outputs and a second set of multi-phase AC phase outputs, wherein the first set of AC phase outputs provides current, each phase output in the first set of AC phase outputs corresponds to a phase output in the second set of AC phase outputs, and wherein each phase output in the first set of AC phase outputs is offset by 180 degrees from a corresponding phase output in the second set of phase outputs; and the first electric motor includes a first set of motor windings and a second set of motor windings configured in anti-parallel with the first set of motor windings, the first set of motor windings being connected to the first set of AC phase outputs, the second set of motor windings being connected to the second set of AC phase outputs, and wherein the electric motor includes a mechanical rotation output.

[0018] In addition to one or more features described herein, the electric motor includes a plurality of winding slots corresponding to each phase of the electric motor, and wherein each winding slot includes a winding from the first set of motor windings and a winding from the second set of motor windings.

[0019] In addition to one or more features described herein, windings of the first and second sets of motor windings from at least a subset of the plurality of winding slots are arranged in radial proximity.

[0020] In addition to one or more features described herein, windings of the first set of motor windings and windings of the second set of motor windings from at least a subset of the plurality of winding slots are arranged circumferentially adjacent.

[0021] In addition to one or more features described herein, windings of the first and second sets of motor windings from at least a subset of the plurality of winding slots are arranged in radial proximity.

[0022] In addition to one or more features described herein, an electrical insulating sheet is disposed between adjacent portions of the first set of windings and the second set of windings.

[0023] In yet another exemplary embodiment, a method of operating an electric motor includes: providing a direct current (DC) power output from an energy storage system to a multi-level dual-output inverter; converting the DC power into a first set of AC phase outputs and a second set of AC phase outputs using the multi-level dual-output inverter, wherein the first set of AC phase outputs includes a first plurality of phases, the second set of AC phase outputs includes a second plurality of phases, each phase in the first set of phase outputs corresponds to a phase in the second set of phase outputs, and each phase is offset 180 degrees from the corresponding phase; providing the first and second AC phase outputs to a single electric motor; and passing current from each phase of the first set of AC phase outputs through a first set of motor windings, and passing current from each phase of the second set of AC phase outputs through a second set of motor windings, wherein the first set of motor windings are arranged anti-parallel to the second set of motor windings, thereby generating a rotational output from the electric motor.

[0024] 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

[0025] Other features, advantages and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings, in which:

[0026] Figure 1 schematically illustrates a vehicle including an electric motor according to an example embodiment;

[0027] Figure 2 Schematic diagram for using stored electrical energy in Figure 1 Vehicle systems that generate rotational forces within a vehicle;

[0028] Figure 3 Schematically shows Figure 1 A phase winding of an electric motor;

[0029] Figure 4 Schematically shows Figure 3 a cross section of a phase winding as shown; and

[0030] Figure 5 Schematically shows Figure 1-4 A cross-sectional view of a phase winding within an electric motor. DETAILED DESCRIPTION

[0031] 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 drawings, corresponding reference numerals represent the same or corresponding parts and features. As used herein, the term "controller" refers to any electronic device configured to receive one or more inputs and generate outputs that can control one or more other systems based at least in part on the received inputs, including processors, field programmable gate arrays (FPGAs), microcomputers, hardware controllers, etc.

[0032] According to an exemplary embodiment, Figure 1 A vehicle 10 is schematically shown having a body 12 that defines at least a passenger compartment 14. The vehicle 10 includes an electrical energy storage system 18, such as a battery. The electrical energy storage system 18 provides electrical power to one or more motors 20 through corresponding inverters 22. The motors convert the electrical energy into mechanical rotation, and the mechanical rotation is provided to vehicle systems, such as wheels 30 or other drive system components.

[0033] Continue to refer Figure 1 Vehicle 10, Figure 2 Schematic diagram showing the use of stored electrical energy in Figure 1 The vehicle system 200 generates a rotational force in a vehicle. The vehicle system 200 includes a direct current (DC) stored electrical energy source 210 (e.g. Figure 1 The DC storage power source 210 is connected to a DC / alternating current (AC) inverter 220, and the inverter 220 converts the DC energy into three-phase AC energy.

[0034] The inverter 220 is a dual-output multi-phase inverter and has a first group of phase outputs 222 and a second group of phase outputs 224. The illustrated example inverter 220 is a three-phase inverter, meaning that each group of phase outputs 222, 224 includes three phases (commonly referred to as A, B, C). Each phase of each phase output 222, 224 is a sine wave output or an approximation of a sine wave output and is offset from each other phase output 222, 224 in the same group of phase outputs 222, 224. In an example, the switches constituting the dual-output multi-phase inverter 220 are configured as an H-type inverter topology or an X-type inverter topology. Alternatively, the switches in the dual-output multi-phase inverter 220 can be any dual-output multi-phase inverter topology, and the switching operation is controlled by a controller 230. The controller 230 can be a dedicated motor controller, a general vehicle controller, or any similar control system.

[0035] The switches within the dual output multiphase inverter 220 are capable of operating at fast switching speeds. As used herein, fast switching speeds refer to inverter switches that can switch at rates exceeding 10 kV / us. In a specific example, the switches that provide fast switching speeds are switches based on gallium nitride (GaN).

[0036] By having a synchronous and complementary switching scheme between the dual inverters, the phase outputs in the first set of phase outputs 222 and the phase outputs in the second set of phase outputs 224 are offset from each other by 180 degrees. In this way, the "A" phase output in the first set of phase outputs 222 and the "A" phase output in the second set of phase outputs are 180 degree offset sine waves, and if the phases are added together, the common mode voltage and each other output current are cancelled. Similarly, the "B" phase output and the "C" phase output will both cancel the corresponding phase output from the other set of phase outputs 222, 224. Providing both outputs of any given phase (A, B, C) to a conventional motor structure would result in a non-operating phase, thereby resulting in a non-operating motor.

[0037] The two sets of phase outputs 222, 224 are provided to a single electric motor 240. The electric motor 240 includes internal sensors according to a conventional electric motor sensing arrangement, and the sensors communicate with a motor controller 230. The motor controller 230 utilizes the sensor readings to control the dual output multilevel inverter 220, thereby controlling the operation of the motor 240 according to known motor control techniques.

[0038] The electric motor 240 converts the AC power input into mechanical rotation and outputs the mechanical rotation via the mechanical rotation output 242. The mechanical rotation output 242 can then be provided to any number of vehicle systems that utilize mechanical rotation, such as the wheels 30. In order to allow the two sets of phase outputs 222, 224 to be used together within a single electric motor 240, each phase (A, B, C) includes two different sets of phase windings, with a first set of windings connected to the first set of phase outputs 222 and a second set of windings connected to the second set of phase outputs 224. The first set of phase outputs 222 are oriented anti-parallel to the second set of phase outputs 224 (see FIG. 2 ). Figure 3 and 4 As used herein, antiparallel refers to a configuration in which windings or other electrical components are physically parallel, while current flows through the windings or other electrical components in opposite directions.

[0039] In addition to the internal sensors within the motor 240, current sensors 250 are located at the phase inputs of the motor 240, with each set of phases A, B, C including a single corresponding current sensor 250. Figure 2 As can be seen in the enlarged view of a single phase of the current sensor 250, one physical magnetic field sensor 252 can sense the combined total input of a given phase by passing the input from the first set of phase output currents and the input from the second set of phase output currents anti-parallel through the magnetic field sensor 252. Using this configuration, N current sensors can be used to sense the net current entering the motor 240, where N is the total number of phases in each set of phase outputs 222, 224, rather than 2*N current sensors required to sense each input individually.

[0040] In yet another example (not shown), one of the current sensors 250 may be omitted, and the total instantaneous current through the input without the current sensor may be calculated by the controller 230 using the known principle that the total current on all three phases output from the inverter is zero, so knowledge of the net current through the N-1 phases will provide sufficient information to calculate the Nth phase despite the lack of direct measurement. In such an example, N-1 current sensors 250 are used, and one of the phases (e.g., phase C) is not directly measured.

[0041] Continue to refer Figure 1 and 2 , Figure 3 A motor 240 including windings 262A, 262B, 262C, 264A, 264B, 264C is schematically shown. Each winding in the first set of windings 262 is connected to the first set of output phases 222, and each winding in the second set of windings 264 is connected to the second set of output phases 224. In the example shown, each set of windings 262, 264 is arranged in a Y-shaped configuration, wherein a dual central neutral node 268 connects one set of windings 262A, 262B and 262C and another set of windings 264A, 264B and 264C, respectively. In some examples, the central neutral node 268 is electrically connected (connected) via a switch 269 or electrically connected via a permanent connection. In an alternative example (not shown), the neutral nodes 268 of each set of windings 262, 264 can be electrically floating (unconnected) relative to each other. Connecting the neutral nodes 268 together provides improved balance between the two sets of windings 262, 264. In examples where the connections are tied together by actively controlled switches, switch 269 provides finer control of the balance and fault tolerance between the phase windings 262 , 264 and is controlled by the motor controller 230 .

[0042] Continue to refer Figure 1-3 , Figure 4 A cross section of two respective windings 262A, 264A is schematically shown. The figure illustrates the direction of current flowing through the windings. The physical orientation of the windings 262A, 264A is parallel, and the windings 262A and 264A are wound adjacent to each other on the same core 402. Current passes through the windings 262A, 264A in opposite directions in an anti-parallel configuration. Passing current through adjacent windings in anti-parallel allows the motor 240 to receive the full amplitude of the current output by the inverter 220, while the current in each winding 262A, 264A does not provide opposing mechanical forces. In addition, the opposing electromagnetic fields provide complete common mode (dv / dt) noise cancellation in the anti-parallel configuration.

[0043] Continue to refer Figure 1-4 , Figure 5A cross-sectional view of a motor 220 is schematically shown. The cross-sectional view includes windings 262, 264, which are arranged in winding slots 510 in an anti-parallel configuration discussed herein. The illustrated example includes a portion of an anti-parallel winding 262A arranged radially adjacent to a corresponding winding (e.g., winding 262A is radially adjacent to winding 264A). Anti-parallel windings 262B, 262C, 264A, 264B, 264C are similarly arranged, and description is omitted to avoid redundancy. As used herein, "radially adjacent" windings refer to a group of windings in which a first winding in the group is immediately radially inward of another winding in the group.

[0044] In addition to the radially adjacent windings 262, 264, each slot 510 includes a portion of an antiparallel winding 262A that is circumferentially adjacent to the corresponding antiparallel winding 262A. As used herein, circumferentially adjacent windings 262, 264 refer to directly adjacent windings that are placed at the same radial distance but are circumferentially offset from each other around the center point 520 of the motor 240.

[0045] In the example shown, the circumferentially adjacent portions are outside of the radially adjacent portions. In alternative examples, the positioning may be mixed, alternating, or reversed to facilitate the manufacture of a particular motor 240. As shown for radially and circumferentially adjacent windings, splitting the windings within slots 510 at adjacent locations provides reduced AC copper losses during high speed switching.

[0046] In some examples, a motor 240 that places multiple sets of anti-parallel windings radially or circumferentially adjacent to each other may generate excessive inter-winding capacitance. In turn, the inter-winding capacitance may generate current due to the change in voltage over time (dV / dt), and the generated current is detrimental to the operation of the motor. In order to reduce the inter-winding capacitance, an insulating sheet 504 is provided between adjacent turns of each set of windings 262, 264. The insulating sheet 504 is made of an electrically insulating material and passively reduces the inter-winding capacitance.

[0047] While the illustrated example includes radially adjacent and circumferentially adjacent turns, it will be appreciated that actual embodiments may include windings arranged within slots 510 in radially adjacent, circumferentially adjacent, or both.

[0048] The configuration and operation described herein provide a simple to construct reverse coupled winding that allows the use of all outputs of a dual output inverter to drive a single motor, thereby providing three-phase control of an electric motor. In addition, one skilled in the art can adapt the configuration to use a motor with any number of phases, such as a six-phase motor, and still fall within the teachings described herein.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 motor arrangement comprising: a dual-output multilevel inverter comprising a first set of alternating current (AC) phase outputs and a second set of multi-phase AC phase outputs, wherein the first set of AC phase outputs provides current, each phase output in the first set of AC phase outputs corresponds to one phase output in the second set of AC phase outputs, and wherein each phase output in the first set of AC phase outputs is offset by 180 degrees from a corresponding phase output in the second set of phase outputs; as well as An electric motor comprising a first set of motor windings and a second set of motor windings arranged antiparallel to the first set of motor windings, the first set of motor windings being connected to a first set of AC phase outputs, the second set of motor windings being connected to a second set of AC phase outputs, and wherein the electric motor comprises a mechanical rotational output.

2. The electric motor arrangement according to claim 1, wherein: The dual output multilevel inverter is a high speed switching inverter, and optionally, wherein the dual output multilevel inverter is a gallium nitride (GaN) switch based inverter.

3. The electric motor arrangement of claim 1 , wherein: The electric motor comprises a plurality of winding slots corresponding to each phase of the electric motor, and wherein each winding slot comprises a winding from the first set of motor windings and a winding from the second set of motor windings, and optionally, further comprises an electrical insulating sheet arranged between adjacent portions of the first set of windings and the second set of windings.

4. The electric motor arrangement according to claim 3, wherein: Windings of the first and second sets of motor windings from at least a subset of the plurality of winding slots are arranged one of radially adjacent and circumferentially adjacent.

5. The electric motor arrangement according to claim 4, wherein: Windings from the first and second sets of motor windings are arranged radially adjacent and circumferentially adjacent.

6. The electric motor arrangement of claim 1, wherein: The first set of motor windings includes a first neutral node, the second set of motor windings includes a second neutral node, and wherein the first neutral node is connected to the second neutral node such that the first and second neutral nodes are electrically connected in at least one operating mode.

7. The electric motor arrangement according to claim 6, wherein: The first and second neutral nodes are connected via an electronically controlled switch.

8. The electric motor arrangement according to claim 7, wherein: The first neutral node is electrically floating relative to the second neutral node.

9. The electric motor arrangement of claim 1 , further comprising a motor controller communicatively coupled to a plurality of current sensors, each of the plurality of current sensors being configured to detect a net current magnitude output through a pair of corresponding phases, and optionally wherein, The plurality of current sensors includes N-1 Hall effect current sensors, where N is the total number of phases of the electric motor.

10. A method of operating an electric motor, comprising: providing a direct current (DC) power output from an energy storage system to a multi-level dual output inverter; converting the DC power into a first set of AC phase outputs and a second set of AC phase outputs using a multi-level dual output inverter, wherein the first set of AC phase outputs includes a first plurality of phases, the second set of AC phase outputs includes a second plurality of phases, each phase in the first set of phase outputs corresponds to a phase in the second set of phase outputs, and each phase is offset by 180 degrees from a corresponding phase; providing first and second AC phase outputs to a single electric motor; as well as Current from each phase of a first set of AC phase outputs is passed through a first set of motor windings, and current from each phase of a second set of AC phase outputs is passed through a second set of motor windings, wherein the first set of motor windings are arranged anti-parallel to the second set of motor windings, thereby generating a rotational output from the electric motor.

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