ELECTRIC MOTOR SYSTEM WITH DC NOISE SUPPRESSION

Abstract

An electric motor configuration includes a multi-stage, dual-output inverter. The inverter has a first and second set of AC phase outputs. The first set of AC phase outputs provides current, with each phase output of the first set corresponding to a phase output of the second set, and each phase output of the first set being shifted 180 degrees relative to the corresponding phase output of the second set. An electric motor has a first and a second, antiparallel set of 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

INTRODUCTION

[0001] The subject matter of the disclosure relates to electric motor configurations, and more particularly to an electric motor system that uses a dual output multi-phase inverter to drive a single electric motor.

[0002] Electric and hybrid vehicles use stored electrical energy to power the rotation of electric motors, with the motors' rotation providing power to the vehicle's mechanical systems. In most cases, the stored electrical energy is provided in the form of direct current (DC), with the electric motor requiring alternating current (AC) to function properly. When this is the case, an inverter is used to convert the DC output of the energy storage device into an AC output that can be used by the electric motor. The power characteristics of the AC outputs are typically controlled via switching rates within the inverter, with the switching rates in turn controlled by a motor controller according to well-known feedback control principles.The rate at which the switches within the inverter are switched corresponds to the amount of common-mode noise within the motor drive system, with faster switching resulting in higher common-mode noise. Excessive common-mode noise can degrade motor operation, resulting in less efficient or less ideal operation.

[0003] As inverter technologies have advanced, the maximum switching speed of inverters has increased, resulting in a corresponding increase in potential common-mode noise within electric motor systems. Therefore, it is desirable to provide a vehicle motor system capable of delivering high switching rates within the inverter and reducing common-mode noise. SUMMARY

[0004] According to an exemplary embodiment, an electric motor configuration comprises a multi-level dual-output inverter including a first group of alternating current (AC) phase outputs and a second group of multi-phase AC phase outputs, wherein the first group of AC phase outputs provides a current, each phase output of the first group of AC phase outputs corresponds to a phase output of the second group of AC phase outputs, and each phase output of the first group of AC phase outputs is shifted 180 degrees from the corresponding phase output of the second group of phase outputs;and an electric motor including a first set of motor windings and a second set of motor windings configured anti-parallel to the first set of motor windings, the first set of motor windings connected to the first group of AC phase outputs, the second set of motor windings connected to the second group of AC phase outputs, and the electric motor including a mechanical rotary output.;

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

[0006] In addition to one or more features described herein, the multi-level dual output 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, each winding slot including windings from the first motor winding set and windings from the second motor winding set.

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

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

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

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

[0012] In addition to one or more features described herein, the first motor winding set includes a first star point and the second motor winding set includes a second star point, the first star point being connected to the second star point such that the first and second star points are electrically connected at least in one mode of operation.

[0013] In addition to one or more features described herein, the first and second star points are connected via an electrically controlled switch.

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

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

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

[0017] According to another exemplary embodiment, a vehicle includes an electrical energy storage system connected to a first electric motor via a first multi-level dual-output inverter, the electrical energy storage system providing direct current (DC) power to the first multi-level dual-output inverter; a first multi-level dual-output inverter including a first group of alternating current (AC) phase outputs and a second group of multi-phase AC phase outputs, the first group of AC phase outputs providing a current, each phase output of the first group of AC phase outputs corresponding to a phase output of the second group of AC phase outputs, and each phase output of the first group of AC phase outputs being shifted 180 degrees from the corresponding phase output of the second group of phase outputs;and a first electric motor including a first motor winding set and a second motor winding set configured anti-parallel to the first motor winding set, the first motor winding set connected to the first group of AC phase outputs, the second motor winding set connected to the second group of AC phase outputs, and the electric motor including a mechanical rotary 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, each winding slot including windings from the first motor winding set and windings from the second motor winding set.

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

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

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

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

[0023] According to another exemplary embodiment, a method of operating an electric motor comprises: providing direct current (DC) output power through an energy storage system to a multi-level dual-output inverter; converting the DC power for a first group of AC phase outputs and for a second group of AC phase outputs using the multi-level dual-output inverter, wherein the first group of AC phase outputs comprises a first number of phases and the second group of AC phase outputs comprises a second number of phases, wherein each phase of the first group of phase outputs corresponds to a phase of the second group of phase outputs and each phase is shifted 180 degrees from the corresponding phase; providing the first and second AC phase outputs to a single electric motor;and directing the current from each phase of the first group of AC phase outputs through a first set of motor windings and from each phase of the second group of AC phase outputs through a second set of motor windings, the first set of motor windings being arranged antiparallel to the second set of motor windings; and thereby generating a rotary output of the electric motor.

[0024] The above-described features and advantages and other features and advantages of the disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 is a schematic diagram of a vehicle including an electric motor according to an exemplary embodiment; Fig. 2 is a schematic representation of a vehicle system for using stored electrical energy to generate rotational power within the vehicle of the Fig. 1 to generate; Fig. 3 a schematic representation of a phase winding of the electric motor of the Fig. 1; Fig. 4 a schematic representation of a cross-section of the phase winding shown in Fig. 3 is shown; and Fig. 5 a schematic representation of a sectional view of the phase windings within the electric motor of the Fig. 1-4. DETAILED DESCRIPTION

[0026] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numbers indicate similar or corresponding portions and features. As used herein, the term controller refers to any electronic device configured to receive one or more inputs and generate an output that can control one or more other systems based at least in part on the one or more received inputs, including processors, field-programmable gate arrays (FPGAs), microcomputers, hardware controllers, and the like.

[0027] According to an exemplary embodiment, Fig. 1 schematically illustrates a vehicle 10 having a body 12 defining at least one passenger compartment 14. The vehicle 10 includes an electrical energy storage system 18, such as a battery. The energy storage system 18 provides power to one or more motors 20 through respective inverters 22. The motors convert the electrical energy into mechanical rotation, which is provided to vehicle systems such as the wheels 30 or other drive system components.

[0028] With continued reference to vehicle 10 of the Fig. 1 shows Fig. 2 schematically shows a vehicle system 200 for using stored electrical energy to generate rotational power within the vehicle of the Fig. 1. The vehicle system 200 includes an electrical energy source 210 with stored direct current (DC) (such as the electrical energy storage system 18 of the Fig. 1). The stored DC electrical energy source 210 is connected to a DC / AC inverter 220, and the inverter 220 converts the DC energy into three-phase AC power.

[0029] The inverter 220 is a multi-phase dual-output inverter and has a first group of phase outputs 222 and a second group of phase outputs 224. The exemplary inverter 220 is a three-phase inverter, meaning that each group of phase outputs 222 and 224 includes three phases (commonly labeled A, B, and C). Each phase of each phase output 222 and 224 is a sine wave output or an approximation of a sine wave output and is offset from every other phase output 222 and 224 in the same group of phase outputs 222 and 224. In one example, the switches comprising the multi-phase dual-output inverter 220 are configured in either an H-type inverter topology or an X-type inverter topology.Alternatively, the switches of the dual-output multiphase inverter 220 may be arranged in any dual-output multiphase inverter topology, and the switching operations are controlled by a controller 230. The controller 230 may be a dedicated motor controller, a general vehicle controller, or any similar control system.

[0030] The switches within the 220-watt multiphase dual-output inverter are capable of operating at a fast switching speed. As used herein, fast switching speed refers to inverter switches capable of switching at a speed greater than 10 kV / µs. In one specific example, the switches providing the fast switching speed are gallium nitride (GaN)-based switches.

[0031] The phase outputs of the first group of phase outputs 222 and the phase outputs of the second group of phase outputs 224 are shifted 180 degrees from each other by a synchronized and complementary switching scheme between the dual inverters. As a result, the "A" phase outputs of the first group of phase outputs 222 and the "A" phase outputs of the second group of phase outputs 224 are 180-degree shifted sine waves and will cancel the common-mode voltage and any other output current when combined. Similarly, both the "B" phase outputs and the "C" phase outputs will cancel the corresponding phase outputs of the other group of phase outputs 222 and 224. Providing both outputs of any given phase (A, B, C) to a conventional motor design will result in an inoperative phase and thus an inoperative motor.

[0032] Both sets of phase outputs 222 and 224 are provided to a single electric motor 240. The electric motor 240 includes internal sensors according to conventional electric motor sensor arrangements, with the sensors in communication with a motor controller 230. The motor controller 230 uses the sensor readings to control the multi-level dual-output inverter 220 and thus the operation of the motor 240 according to known motor control techniques.

[0033] The electric motor 240 converts AC input power into mechanical rotation and outputs the mechanical rotation via a mechanical rotary output 242. The mechanical rotary output 242 can then be provided to any number of vehicle systems, such as the wheels 30, that utilize mechanical rotation. To enable both phase outputs 222 and 224 to be used together in a single electric motor 240, each phase (A, B, C) includes two unique groups of phase windings, with the first group of windings connected to the first group of phase outputs 222 and the second group of windings connected to the second group of phase outputs 224. The first group of phase outputs 222 is arranged antiparallel to the second group of phase outputs 224 (see Fig. 3 and Fig. 4). As used here, antiparallel refers to a design in which the windings or other electrical elements are physically parallel and current flows through the windings or other electrical elements in opposite directions.

[0034] In addition to the internal sensors within the motor 240, the current sensors 250 are positioned at the phase inputs of the motor 240, with each group of phases A, B, and C containing a single corresponding current sensor 250. As shown in the enlarged view of a single phase of the current sensor 250 in Fig. 2, a physical magnetic field sensor 252 can sense a combined total input for a given phase by passing the inputs of the first group of phase output currents and the inputs of the second group of phase output currents anti-parallel through the magnetic field sensor 252. Using this configuration, the net current entering the motor 240 can be sensed using N current sensors, where N is the sum of the number of phases in each group of phase outputs 222 and 224, rather than using 2 × N current sensors required to sense each input individually.

[0035] According to another example (not shown), one of the current sensors 250 may be omitted, whereby the total instantaneous current through the input without the current sensor can be calculated by the controller 230 using the known principle that the total current output from the inverter is 0 across all three phases, whereby knowledge of the net current through N-1 phases provides sufficient information to calculate the Nth phase despite a lack of direct measurement. In such examples, N-1 current sensors 250 are used, and one of the phases (e.g., phase C) is not directly measured.

[0036] With continued reference to the Fig. 1 and Fig. 2 shows Fig. 3 schematically illustrates motor 240, which includes windings 262A, 262B, 262C, 264A, 264B, and 264C. Each winding of the first winding set 262 is connected to the first group of phase outputs 222, and each winding of the second winding set 264 is connected to the second group of phase outputs 224. According to the example shown, each winding set 262 and 264 is arranged in a Y configuration, with dual central star points 268 separately connecting one set of windings 262A, 262B, and 262C and another set of windings 264A, 264B, and 264C. In some examples, the central star points 268 are electrically connected (linked) via a switch 269 or electrically connected via a permanent connection. In alternative examples (not shown), the star points 268 of each winding set 262 and 264 may be electrically floating (not connected) with respect to one another.Linking the star points 268 provides improved balancing between the two sets of windings 262 and 264. In examples where the connection is linked via an actively controlled switch, the switch 269 provides finer control of the balancing and fault tolerance between the phase windings 262 and 264, with the switch 269 being controlled by the motor controller 230.

[0037] With continued reference to the Fig. 1-3 shows Fig. 4 shows a schematic cross-section of two corresponding windings 262A and 264A. The illustration demonstrates the direction of current flow through the windings. The physical orientation of windings 262A and 264A is parallel, with windings 262A and 264A wound around the same core 402 being adjacent to each other. Current is conducted in opposite directions through windings 262A and 264A in an anti-parallel configuration. Conducting current anti-parallel through the adjacent windings allows motor 240 to receive the full magnitude of the current output by inverter 220 without the currents in windings 262A and 264A providing opposing mechanical forces. Furthermore, the opposing electromagnetic fields in the anti-parallel configuration provide complete common-mode noise (dv / dt) rejection.

[0038] With continued reference to the Fig. 1-4, shows Fig. 5 is a schematic representation of a cross-sectional view of motor 220. The cross-sectional view includes windings 262 and 264 disposed within winding slots 510 in the anti-parallel configuration discussed herein. The example shown includes a portion of anti-parallel windings 262A disposed radially adjacent to corresponding windings (e.g., winding 262A is radially adjacent to winding 264A). Anti-parallel windings 262B, 262C, 264A, 264B, and 264C are similarly arranged, with illustration omitted to avoid redundancy. As used herein, "radially adjacent" windings refers to a winding set in which a first winding of the set is located radially immediately inside the other winding of the set.

[0039] In addition to the radially adjacent windings 262 and 264, each slot 510 includes a portion of the antiparallel windings 262A that is circumferentially adjacent to the corresponding antiparallel winding 262A. As used herein, circumferentially adjacent windings 262 and 264 refer to immediately adjacent windings that are spaced the same radially apart but circumferentially offset from each other about a center point 520 of the motor 240.

[0040] In the example shown, the circumferentially adjacent sections are located outside the radially adjacent sections. In other examples, the positioning may be mixed, alternated, or reversed to facilitate the manufacture of a particular motor 240. As shown for both the radially and circumferentially adjacent windings, separating the windings within slots 510 into adjacent positions provides reduced AC copper loss during high-speed switching.

[0041] In some examples, motors 240 in which the antiparallel winding sets are placed radially or circumferentially adjacent to each other may generate excessive interwinding capacitance. The interwinding capacitance, in turn, generates current due to the change in voltage over time (dV / dt), and the generated current may be detrimental to motor operation.

[0042] To reduce inter-winding capacitance, an insulating plate 504 is disposed between the adjacent turns of each winding set 262 and 264. The insulating plate 504 is constructed of an electrically insulating material and passively reduces inter-winding capacitance.

[0043] Although the example shown includes both radially adjacent and circumferentially adjacent turns, it should be understood that a practical embodiment may include turns configured to be either radially adjacent, circumferentially adjacent, or both within slots 510.

[0044] The configuration and operation described herein provides a simple-to-construct, reverse-coupled winding that enables three-phase control of an electric motor using the full power of a dual-output inverter to drive a single motor. Furthermore, the configuration can be adapted by those skilled in the art to motors using any number of phases, such as six-phase motors, while still remaining within the teachings described herein.

[0045] The terms "a" and "an" do not imply a limitation of number, but rather denote the presence of at least one of the referenced elements. The term "or" means "and / or" unless clearly indicated otherwise by context. A reference throughout the application text to "an aspect" means that a particular element (e.g., a feature, structure, step, or property) described in connection with the aspect is included in at least one aspect described herein and may or may not be present in further aspects. In addition, it is to be understood that the described elements in the various aspects may be combined in any suitable manner.

[0046] When an element, such as a layer, film, region, or substrate, is referred to as "on" another element, it may be directly adjacent to the other element or may also have intervening elements present. In contrast, when an element is referred to as "directly adjacent" to another element, no intervening elements are present.

[0047] Unless otherwise specified herein, all examination standards shall be the most recent standard in force as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the examination standard appears.

[0048] Unless otherwise defined, 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.

[0049] While the above disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements without departing from the scope thereof. Additionally, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its essential scope. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but will include all embodiments falling within its scope.

Claims

[1] Electric motor configuration that includes: a multi-level dual-output inverter including a first group of alternating current (AC) phase outputs and a second group of multi-phase AC phase outputs, wherein the first group of AC phase outputs provides a current, each phase output of the first group of AC phase outputs corresponds to a phase output of the second group of AC phase outputs, and each phase output of the first group of AC phase outputs is offset by 180 degrees from the corresponding phase output of the second group of phase outputs; and an electric motor including a first set of motor windings and a second set of motor windings configured anti-parallel to the first set of motor windings, the first set of motor windings connected to the first group of AC phase outputs, the second set of motor windings connected to the second group of AC phase outputs, and the electric motor including a mechanical rotary output. [2] The electric motor configuration of claim 1, wherein the multi-level dual output inverter is a high-speed switching inverter and the multi-level dual output inverter is optionally a gallium nitride (GaN) switch-based inverter. [3] The electric motor configuration of claim 1, wherein the electric motor includes a plurality of winding slots corresponding to each phase of the electric motor, each winding slot including windings from the first motor winding set and windings from the second motor winding set, and optionally further including an electrically insulating plate disposed between the adjacent portions of the first winding set and the second winding set. [4] The electric motor configuration of claim 3, wherein the windings of the first motor winding set and the second motor winding set are arranged either radially adjacent or circumferentially adjacent in at least a subset of the plurality of winding slots. [5] The electric motor configuration of claim 3, wherein the windings of the first motor winding set and the second motor winding set are arranged adjacent both radially and circumferentially. [6] The electric motor configuration of claim 1, wherein the first motor winding set includes a first star point and the second motor winding set includes a second star point, and the first star point is connected to the second star point such that the first and second star points are electrically connected in at least one operating mode. [7] An electric motor configuration according to claim 6, wherein the first and second star points are connected via an electrically controlled switch. [8] Electric motor configuration according to claim 7, wherein the first star point is electrically potential-free relative to the second star point. [9] The electric motor configuration of claim 1, further comprising a motor controller communicatively coupled to a plurality of current sensors, each current sensor of the plurality of current sensors configured to detect a net current magnitude flowing through a pair of the corresponding phase outputs, the plurality of current sensors optionally comprising N-1 Hall effect current sensors, and N is the sum of the number of phases of the electric motor. [10] A method of operating an electric motor, comprising: Providing direct current (DC) output power through an energy storage system to a multi-level dual output inverter; Converting the DC power into a first group of AC phase outputs and a second group of AC phase outputs using the multi-level dual output inverter, wherein the first group of AC phase outputs comprises a first number of phases, the second group of AC phase outputs comprises a second number of phases, each phase of the first group of phase outputs corresponds to a phase of the second group of phase outputs, and each phase is shifted 180 degrees from the corresponding phase; Providing the first and second AC phase outputs for a single electric motor; and Passing the current from each phase of the first group of AC phase outputs through a first set of motor windings and passing the current from each phase of the second group of AC phase outputs through a second set of motor windings, the first set of motor windings being arranged anti-parallel to the second set of motor windings; and thereby generating a rotary output by the electric motor.

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