CN110677081A

CN110677081A - Method and apparatus for brushless motor control

Info

Publication number: CN110677081A
Application number: CN201910984128.9A
Authority: CN
Inventors: J.T.穆拉; N.斯皮克; A.高利克; J.克里什纳萨米
Original assignee: Brooks Automation Inc
Current assignee: Borucos Automation Usa Co ltd; Borukos Automation Holding Co ltd
Priority date: 2013-11-13
Filing date: 2014-11-13
Publication date: 2020-01-10
Anticipated expiration: 2034-11-13
Also published as: TW201539968A; TWI692931B; CN110677081B; CN105900332A; CN105900332B; EP3069443A1; CN117318541A; EP3069443A4

Abstract

A variable reluctance motor load mapping apparatus comprising: a frame; an interface disposed on a frame configured for mounting a variable reluctance motor; a static load unit mounted to the frame and coupled to the variable reluctance motor; and a controller communicably coupled to the static load unit and the variable reluctance motor, the controller configured to: selecting at least one motor phase of the variable reluctance motor, energizing the at least one motor phase, and receiving motor operation data from at least the static load unit for mapping and generating a batch of motor operation data look-up tables.

Description

Method and apparatus for brushless motor control

The present application is a divisional application of an invention application having an application date of 11/13/2014, an application number of 201480073094.3, entitled "method and apparatus for brushless motor control".

Background

1. Field of the invention

Exemplary embodiments relate generally to electric machines, and more particularly to control of electric machines.

2. Brief introduction to related developments

In general, variable (or switched) reluctance motors (VRMs) are sought to be cost effective alternatives to brushless dc motors. Variable reluctance motors do not require magnets and are mechanically simple in construction, however, their use for precise control remains challenging due to highly non-linear relationships between, for example, phase current, rotor electrical position, torque, and geometry. One of the main challenges in the accurate control of variable reluctance machines is: smooth and ripple-free pre-specified torque is provided at any given position of the rotor. The torque ripple inherent in variable reluctance motors can be due to modeling uncertainty. Thus, the performance of a variable reluctance motor may depend on the existence of an accurate commutation model that relates the desired torque to the phase current and position. Furthermore, typical feedback loops (as in conventional off-the-shelf amplifiers) are usually designed for fixed inductance and are optimally tuned, and variable reluctance motors usually do not have fixed inductance. In a variable reluctance motor, variations in motor coil or winding inductance are desirable because this is the primary mechanism by which the variable reluctance motor generates mechanical torque.

For example, in robotic servo applications, servo performance may be affected by the dynamic response of the actuator or motor. Slow motor response may limit the response speed of the servo system. The use of motors as actuators in robotic servo applications typically assumes that the motor response is at least an order of magnitude faster than the servo loop and is typically ignored in system models, especially in brushless dc motors. However, variable reluctance motors have a rather slow response so that some adjustment of the commutation strategy can be guaranteed to compensate for the slow response. As such, substantially instantaneous torque control of a variable reluctance motor drive for positioning servo applications may be required. Transient torque control may be provided, for example, by a digital electronic controller that may control the current through each motor phase as a function of motor position and required transient torque. Determining the current required in each motor phase based on motor position and torque may be referred to as current commutation. In a three-phase permanent magnet brushless motor (where the three phase currents are 120 degrees apart), the current through each motor winding is sinusoidal and a uniquely defined function of rotor position and torque. On the other hand, the phase current in a variable reluctance motor is not sinusoidal, but has a shape derived from the motor torque curve. The motor torque curve of the motor is measured or determined from finite element analysis of a motor model. In general, for a switched reluctance motor, torque may be a function of motor position and current per phase. The purpose of current commutation is to determine the required current in each motor phase as a function of motor position and motor torque. Advantageously, the effect of torque ripple is minimized when controlling a variable reluctance motor. It would also be advantageous to provide an optimal commutation scheme that provides a method to calculate the current in each motor phase to accomplish one or more optimization criteria. It would further be advantageous to provide a control system that mitigates the dependence on the exact commutation pattern for a variable reluctance motor.

Drawings

The foregoing aspects and other features of the disclosed embodiments are explained in the following description, taken in connection with the accompanying drawings, wherein:

1A-1D are schematic diagrams of a substrate processing tool in accordance with aspects of the disclosed embodiments;

FIGS. 1E and 1F are schematic diagrams of portions of a variable reluctance motor in accordance with aspects of the disclosed embodiments;

FIG. 2 illustrates an exemplary table in accordance with aspects of the disclosed embodiments;

FIG. 3 illustrates another exemplary table in accordance with aspects of the disclosed embodiments;

FIG. 4 is a schematic diagram of portions of the variable reluctance motor shown in FIGS. 1E and 1F in accordance with aspects of the disclosed embodiments;

FIG. 5 is a schematic illustration of an iso-torque generating station in accordance with aspects of the disclosed embodiments;

FIG. 5A illustrates a flow diagram in accordance with aspects of the disclosed embodiments;

FIG. 6 illustrates a portion of an iso-torque curve table in accordance with aspects of the disclosed embodiments;

FIG. 7 illustrates an exemplary look-up table in accordance with aspects of the disclosed embodiments;

8A and 8B illustrate an exemplary phase current meter with respect to rotor position in accordance with aspects of the disclosed embodiments;

FIGS. 9A and 9B illustrate an exemplary motor input power table with respect to rotor position in accordance with aspects of the disclosed embodiments;

10A and 10B illustrate portions of an iso-torque curve table in accordance with aspects of the disclosed embodiments;

11A and 11B are schematic diagrams of portions of a variable reluctance motor in accordance with aspects of the disclosed embodiments;

FIGS. 12 and 13 illustrate schematic diagrams of a transport device and its control system in accordance with aspects of the disclosed embodiments;

FIGS. 14 and 15 illustrate exemplary look-up tables in accordance with aspects of the disclosed embodiments;

FIG. 16 illustrates an exemplary look-up table in accordance with aspects of the disclosed embodiments; and

FIG. 17 illustrates a flow diagram in accordance with aspects of the disclosed embodiments.

Detailed Description

In accordance with aspects of the disclosed embodiments, there is thus provided a switched reluctance brushless motor or motor and an optimal commutation scheme or strategy therefor. The commutation scheme or strategy refers to determining the current in each motor phase based on the motor position and the desired torque. Although aspects of the disclosed embodiments will be described with reference to the accompanying drawings, it should be understood that aspects of the disclosed embodiments can be embodied in various forms. In addition, any suitable size, shape or type of elements or materials could be used.

Referring to fig. 1A-1D, schematic diagrams of substrate processing apparatuses or tools incorporating aspects of the disclosed embodiments further disclosed herein are shown.

Referring to fig. 1A and 1B, a processing apparatus, such as, for example, a semiconductor tool station 1090, is illustrated in accordance with aspects of the disclosed embodiments. Although semiconductor tools are shown in the figures, aspects of the disclosed embodiments described herein may be applied to any tool station or application that employs a robotic manipulator. In this example, tool 1090 is shown as a cluster tool, however, aspects of the disclosed embodiments may be applied to any suitable tool station, such as, for example, a linear tool station, such as the linear tool stations shown in fig. 1C and 1D and described in the following applications: U.S. patent application No. 11/442,511 entitled "linear Distributed Semiconductor Processing Tool" filed on 26.5.2006, the entire contents of which are incorporated herein by reference. The tool station 1090 generally includes an atmospheric front end 1000, a vacuum load lock 1010, and a vacuum back end 1020. In other aspects, the tool station can have any suitable configuration. The components of each of the front end 1000, load lock 1010, and back end 1020 may be coupled to a controller 1091, which controller 1091 may be part of any suitable control architecture, such as, for example, a cluster architecture controller. The control system may be a closed loop controller having a master controller, a cluster controller, and an autonomous remote controller, such as the controllers disclosed in the following applications: U.S. patent application No. 11/178, 615 entitled "Scalable Motion Control System," filed on 11.7.2005, the entire contents of which are incorporated herein by reference. In other aspects, any suitable controller and/or control system may be utilized.

In one aspect, the front end 1000 generally includes a load port module 1005 and a mini-environment 1060, such as, for example, an Equipment Front End Module (EFEM). The load port module 1005 may be: a case opener/loader to tool standard (BOLTS) interface that conforms to SEMI standard E15.1, E47.1, E62, E19.5, or E1.9 for a 300 mm load port, a front opening or bottom opening case/pod, and a cassette. In other aspects, the load port module may be configured as a 200 mm wafer interface or any other suitable substrate interface, such as, for example, a larger or smaller wafer or flat panel display. Although two load port modules are shown in fig. 1A, in other aspects any suitable number of load port modules may be incorporated into the front end 1000. The load port module 1005 may be configured to receive substrate carriers or cassettes 1050 from an overhead transport system, an automated guided vehicle, a personnel guided vehicle, a rail guided vehicle, or from any other suitable transport method. The load port module 1005 may interface with the mini-environment 1060 through the load port 1040. The load port 1040 may allow substrates to pass between the substrate cassette 1050 and the mini-environment 1060. The mini-environment 1060 generally includes any suitable transfer robot 1013, the transfer robot 1013 may incorporate one or more aspects of the disclosed embodiments described herein. In one aspect, robot 1013 may be a rail mounted robot, such as, for example, the rail mounted robot described in U.S. patent No. 6,002,840, which is incorporated herein by reference in its entirety. Mini-environment 1060 may provide a controlled clean area for substrate transfer between multiple load port modules.

The vacuum load lock 1010 may be located between the mini-environment 1060 and the back end 1020 and connected to the mini-environment 1060 and the back end 1020. It is noted that the terminology used herein"vacuum" may mean, for example, 10^-5A high vacuum of Torr or less in which the substrate is processed. The load lock 1010 generally includes atmospheric and vacuum slit valves. The slot valve may provide environmental isolation for backing out the load lock after loading the substrate from the atmospheric front end and for maintaining a vacuum in the transport chamber while venting the lock with an inert gas such as nitrogen. The load lock 1010 may also include an aligner 1011 for aligning a reference point of the substrate with a desired processing position. In other aspects, the vacuum load lock may be located in any suitable location of the processing apparatus and have any suitable configuration.

The vacuum back end 1020 generally includes a transport chamber 1025, one or more processing stations 1030, and any suitable transfer robot 1014, which transfer robot 1014 may incorporate one or more aspects of the disclosed embodiments described herein. The transfer robot 1014 is described below and may be located within a transport chamber 1025 to transport substrates between the load lock 1010 and the plurality of processing stations 1030. Processing station 1030 may operate on a substrate through various deposition, etching, or other types of processing to form circuits or other desired structures on the substrate. Typical processes include, but are not limited to, thin film processes using vacuum, such as plasma etching or other etching processes, Chemical Vapor Deposition (CVD), Plasma Vapor Deposition (PVD), implantation such as ion implantation, metrology, Rapid Thermal Processing (RTP), dry lift-off Atomic Layer Deposition (ALD), oxidation/diffusion, nitride formation, vacuum lithography, epitaxial growth (EPI), wire bonding and evaporation or other thin film processes using vacuum pressure. The processing station 1030 is connected to the transport chamber 1025 to allow substrates to be transferred from the transport chamber 1025 to the processing station 1030, and vice versa.

Referring now to fig. 1C, a schematic plan view of a linear substrate processing system 2010 is shown in which tool interface segments 2012 are mounted to a transport pod module 3018 such that the interface segments 2012 generally face (e.g., face inward) but are offset from the longitudinal axis X of the transport pod 3018. The transport room module 3018 may extend in any suitable direction by attaching other

transport room modules

3018A, 3018I, 3018J to

interfaces

2050, 2060, 2070 as described in U.S. patent application No. 11/442,511, which was previously incorporated herein by reference. Each

transport chamber module

3018, 3019A, 3018I, 3018J includes any suitable substrate transport 2080, which substrate transport 2080 may include one or more aspects of the disclosed embodiments described herein for transporting substrates throughout processing system 2010 and to and from, for example, processing modules PM. As can be realized, each chamber module is capable of maintaining an isolated or controlled atmosphere (e.g., N2, clean air, vacuum).

Referring to fig. 1D, a schematic front view of an exemplary processing tool 410 is shown, such as may be taken along a longitudinal axis X of a linear transport chamber 416. In aspects of the disclosed embodiment shown in fig. 1D, the tool interface section 12 may be representatively connected to a transport compartment 416. In this aspect, the interface section 12 may define one end of a tool transport compartment 416. As seen in fig. 1D, the transport chamber 416 may have another workpiece entry/exit station 412, for example, at an opposite end of the interface station 12. In other aspects, other entry/exit stations for inserting/removing workpieces from the transport compartment may be provided. In one aspect, the interface section 12 and the entry/exit station 412 may allow for loading and unloading of workpieces from the tool. In other aspects, the workpiece may be loaded onto the tool from one end and removed from the other end. In one aspect, the transport chamber 416 may have one or more transfer chamber modules 18B and 18 i. Each chamber module is capable of maintaining an isolated or controlled atmosphere (e.g., N2, clean air, vacuum). As previously mentioned, the construction/arrangement of the transport chamber modules 18B and 18i, the load lock modules 56A and 56B, and the workpiece stations forming the transport chamber 416 shown in fig. 1D are merely exemplary, and in other aspects, the transport chamber may have more or fewer modules arranged in any desired modular arrangement. In the aspect shown, the station 412 may be a load lock. In other aspects, the load lock module may be located between end entrance/exit stations (similar to station 412), or adjacent transport chamber modules (similar to module 18 i) may be configured to operate as load locks. As also previously mentioned, transport room modules 18B and 18i have one or more corresponding transport devices 26B and 26i located therein, which corresponding transport devices 26B and 26i may include one or more aspects of the disclosed embodiments described herein. Transport apparatus 26B and 26i of each transport room module 18B and 18i may cooperate to provide a workpiece transport system 420 that is linearly distributed in the transport room. In this aspect, the transport apparatus 26B may have a common SCARA arm configuration (although in other aspects, the transport arm may have any other desired arrangement, such as a frog-leg configuration, a telescoping configuration, a bi-directionally symmetrical configuration, etc.). In aspects of the disclosed embodiment shown in fig. 1D, the arms of transport apparatus 26B may be arranged to provide an arrangement that may be referred to as a rapid exchange arrangement that allows transport to rapidly exchange wafers with pick/place locations, which will also be described further below. The transport arm 26B may have suitable drive segments, such as those described below, to provide any suitable number of degrees of freedom for each arm (e.g., independently rotating about the shoulder and elbow joints via Z-axis motion). As seen in fig. 1D, in this aspect, the

modules

56A, 56, 30i may be interstitially located between the transfer chamber modules 18B and 18i and may define appropriate processing modules, load locks, buffer stations, metering stations, or any other desired stations. For example, the shimming modules, such as the load locks 56A and 56 and the work station 30i, may have fixed work piece carriers/shelves 56S, 56S1, 56S2, 30S1, 30S2, respectively, or work pieces, which fixed work piece carriers/shelves 56S, 56S1, 56S2, 30S1, 30S2 may cooperate with transport arms to effect transport, along the linear axis X of the transport chamber, through the length of the transport chamber. For example, workpieces may be loaded into the transport chamber 416 through the interface section 12. The workpiece may be placed on the shelf of the load lock module 56A by using the transport arm 15 of the interface section. In the load lock module 56A, workpieces may be moved between the load lock module 56A and the load lock module 56 by the transport arm 26B in module 18B, and in a similar and continuous manner between the load lock 56 and the workpiece station 30i by using arm 26i (in module 18 i) and between the station 30i and the station 412 by using arm 26i in module 18 i. The process may be reversed completely or partially to move the workpiece in the opposite direction. Thus, in one aspect, the workpiece may be moved in any direction along the axis X and to any position along the transport chamber, and may be loaded to and unloaded from any desired module (process or otherwise) in communication with the transport chamber. In other aspects, a interstitial transport chamber module having static workpiece supports or racks may not be provided between the transport chamber modules 18B and 18 i. In these aspects, transport arms adjacent to the transport chamber module may pass the workpiece directly from the end effector through or one transport arm transfers to the end effector of another transport arm to move the workpiece through the transport chamber. The processing station modules may operate on the substrate through various deposition, etching, or other types of processing to form circuits or other desired structures on the substrate. The processing station module is connected to the transport chamber module so as to allow transfer of the substrates from the transport chamber to the processing station and vice versa. Suitable examples of processing tools having similar general features to the processing apparatus shown in fig. 1D are described in U.S. patent application serial No. 11/442,511, the entire contents of which are previously incorporated herein by reference.

The preferred commutation scheme described herein is the following: the scheme provides a method to calculate the current in each phase of the brushless motor to accomplish one or more optimization criteria. In aspects of the disclosed embodiments, an optimal commutation scheme can substantially maximize torque subject to certain constraints, which will be described in more detail below. The commutation schemes described herein may be applicable to any motor type, but are shown herein with reference to, for example, a variable reluctance motor for exemplary purposes. Fig. 1E and 1F illustrate portions of a brushless motor with a passive rotor in accordance with aspects of the disclosed embodiments. The exemplary configuration of the direct drive brushless motor shown in fig. 1E and 1F is representative of such machines having a rotary configuration and is used to facilitate the description of aspects of the embodiments herein. It should be noted that aspects of the embodiments described further below apply in a similar manner to linear brushless motors. In one aspect, as mentioned above, the brushless electric machine with passive rotor may be a variable or switched reluctance motor 100 connected to any suitable controller 400, the controller 400 configured to control the operation of the motor 100 as described herein. In one aspect, the controller 400 may have a distributed architecture substantially similar to that described in U.S. patent No. 7,904,182 entitled "Scalable Motion Control System," the entire contents of which are incorporated herein by reference.

Here, the variable reluctance motor 100 includes: a housing 101, at least one stator 103 disposed within the housing, and at least one rotor 102 corresponding to each of the at least one stator 103. Each of the at least one stator 103 may have any suitable number of stator salient poles 103P (e.g., no magnets), each stator salient pole 103P having a motor winding or coil 104. Each of the at least one rotor 102 may also have any suitable number of rotor salient poles 102P such that the rotor is configured to form a closed magnetic flux loop with the stator. For exemplary purposes only, the variable reluctance motor 100 is shown as a four-phase motor having six rotor poles and eight stator poles, but in other aspects the variable reluctance motor may have any suitable number of motor phases, any suitable number of rotor poles, and any suitable number of stator poles. Here, the at least one rotor 102 is disposed within or otherwise substantially surrounded by the respective stator 103, but in other aspects the stator may be disposed within or otherwise substantially surrounded by the respective rotor. Also, in this aspect, one or more stator/rotor pairs may be arranged in a stack (e.g., axially spaced apart from each other along the rotational axis of the variable reluctance motor 100), however, in other aspects, the stator/rotor pairs may be arranged in a nested configuration, wherein each stator/rotor pair is radially nested or otherwise substantially surrounded by another stator/rotor pair. The variable reluctance motor 100 may be configured to operate in an atmospheric environment and/or a vacuum environment, wherein the stationary components of the motor are isolated from vacuum conditions, for example, as described in the following patent applications: U.S. provisional patent application entitled "SealedRobot Drive" filed on 13.11.2013, having attorney docket number 390P014939-US (- #1), the entire contents of which are incorporated herein by reference. The variable reluctance motor may also include features as described in the following patent applications: U.S. provisional patent application No. 390P014680-US (- #1), entitled "Axial Flux Motor", filed on 13.11.2013, and incorporated herein by reference in its entirety.

As may be realized, each of the at least one rotors 102 may be coupled to a respective drive shaft of any suitable drive shaft assembly 110. In this aspect, the drive shaft assembly 110 is shown as a coaxial drive shaft assembly having two drive shafts, but in other aspects there may be more or less than two drive shafts, with each drive shaft corresponding to a respective rotor and stator pair (e.g., motor) of a brushless motor. In other aspects, the drive shaft assembly may include a single drive shaft or coaxial drive shafts arranged side-by-side. As may be realized, the drive shaft assembly 110 may be connected to any suitable device, such as a robotic transport device 111. The robotic transport 111 may be, for example, any suitable transport arm including, but not limited to: a bi-directionally symmetric robotic arm assembly, a SCARA type robotic arm assembly, a telescoping robotic arm assembly, a robotic arm assembly with a lost motion switch, or any other suitable robotic arm assembly that includes one or more robotic arms and utilizes coaxial or side-by-side drive shafts. Referring now to fig. 2 and 3, torque versus position curves for different current intensities on a single motor phase are illustrated in accordance with aspects of the disclosed embodiments. In one aspect, referring also to fig. 1E and 1F, each motor phase may include two coils 104 wired in series and positioned diametrically opposite each other, however, in other aspects, each motor phase may include any suitable number of coils wired in any suitable manner and located in any suitable position relative to each other. Generally, two of the motor phases may be energized to generate a desired or otherwise predetermined magnitude and direction of torque, except in, for example, the following electrical positions: in this position, only one motor phase contributes to the motor torque, as shown in fig. 3, where only a single motor phase is energized when, for example, the rotor is about 0, 15, and 30 degrees. It should be appreciated that motor positions of approximately 0, 15, and 30 degrees are merely exemplary, and in other aspects, the rotor position that powers only a single motor phase may be any suitable rotor position, depending on the number of stator and rotor poles and other motor construction factors.

In general, several methods have been proposed to define the desired phase currents or the desired commutation strategy in order to achieve the desired amount of torque for any given time and rotor position. These methods attempt to minimize torque ripple by: it is assumed that each phase torque contribution can be quantified independently by measurements such as those shown in fig. 2. However, these approaches typically ignore the effect of the adjacent phases once they are energized. For example, as adjacent coils are energized, the inductance of one of the active coils changes. Thus, the shape of the torque curves shown, for example, in fig. 2 and 3 may vary depending on the current adjacent to the phase. This can result in torque ripple of the variable reluctance motor 100 if the change in inductance of the active coil when adjacent coils are energized is not taken into account.

In one aspect of the disclosed embodiments, a method is provided for obtaining a commutation strategy that can naturally capture the effects of mutual inductance (e.g., the effects of inductance on one coil when energizing an adjacent coil) and thus substantially minimize the effects of torque ripple in the commutation of a variable reluctance motor. Referring now to fig. 4 and 5, in one aspect, a commutation strategy comprises: an apparatus, such as the torque value generating station 510, is provided to which the variable reluctance motor 100 is connected (fig. 5A, block 550). The station or apparatus provides a system for empirically characterizing the relationship between the current, position and desired torque (or force) of a brushless motor (e.g., a rotary or linear motor arrangement as may be applied). The variable reluctance motor 100 may be operated in any suitable manner over a batch of phase currents (e.g., one or more phase commutation phase currents are varied to produce a predetermined torque) (fig. 5A, block 551) and/or at a batch of rotor electrical positions (e.g., phase currents are measured at different rotor positions for different torques) (fig. 5A, block 552), the batch of phase currents and the batch of rotor electrical positions representing an operating range of the variable reluctance motor 100. The measured currents, torques, and rotor electrical positions are recorded (fig. 5A, block 553) and the torque curve (e.g., values) and phase current combinations at the predetermined electrical positions (e.g., a batch of torque current meters is generated for a given rotor position) may be recorded and/or plotted by any suitable controller 400' (fig. 5A, block 554). In one aspect, the torque value generating station 510 may include any suitable frame 520, to which any suitable load cell 500 and variable reluctance motor 100 are mounted. In one aspect, the load unit 500 may be a static load unit. The variable reluctance motor 100 may be coupled to the load unit 500 in any suitable manner to provide an operating resistance to the variable reluctance motor 100. The variable reluctance motor 100 and/or the auxiliary unit 500 may be communicatively connected to, for example, a controller 400' for operating the variable reluctance motor 100 and recording/mapping the motor torque, and more particularly, for having any suitable number of positions sufficient to describe the relationship between the iso-torque curve, the corresponding phase current, and the rotor position throughout a rotor cycle or period (e.g., 360 degrees of electrical position). The format of these values may be represented in any manner suitable for programming the controller, such as, for example, a look-up table as will be described further below. It should be noted that, according to another aspect, data or values characterizing the relationship between the generated torque (force), current and position of the variable reluctance motor of a desired form and characteristics may be generated by using a modeling technique such as a numerical method or finite element modeling.

In this aspect, the stator 103 of the variable reluctance motor 100 is inShown in fig. 4. Here, the stator coils and an exemplary wiring manner of the stator coils are schematically shown, and the rotor has been omitted for clarity. As described above, each motor phase a-D includes two diametrically opposed coils wired in series. For example, motor phase a includes coils 104a1 and 104a2, motor phase B includes coils 104B1 and 104B2, motor phase C includes coils 104C1 and 104C2, and motor phase D includes coils 104D1 and 104D 2. Further, in other aspects, the motor may have more or less than four phases arranged and wired in any suitable manner. The terminal leads of each motor phase may be wired to any suitable respective current source, such as, for example, I for phase a and phase B₁And I₂. In one aspect, each current source may be independently set (e.g., by any suitable controller 400') to generate a desired current through its respective phase. At a given rotor position, phase a and phase B are energized with a predetermined current and the load unit 500 registers the resultant static torque. Current I at each rotor position and in a given phase a₁Current I in phase B₂Varying between, for example, 0 to any suitable predetermined maximum current value. In one aspect, the predetermined maximum current value may be a worst condition for the operating range of the variable reluctance motor 100. The process (e.g., varying phase B for constant values of rotor position and phase a current) is for a batch of currents I₁And I₂And a batch of rotor electrical positions, e.g., a batch of currents and a batch of rotor electrical positions representing the operating range of the variable reluctance motor 100. For example, the operating range may be between about 0 electrical degrees to about 360 electrical degrees. At each point in the batch of currents and the batch of rotor electrical positions, static torque is measured and plotted with respect to the corresponding rotor electrical position and the corresponding phase current combination to form a batch of equal torque curves (fig. 5A, block 553). As previously mentioned, in other aspects, the characterization data of the motor may be generated by modeling or simulation. An exemplary plot or table of iso-torque curves (e.g., curves of constant torque at a given electrical position of the rotor) is shown in fig. 6.It should be noted that although the term "curve" is used herein to describe and illustrate an iso-torque curve, the illustration is for exemplary purposes only, and in other aspects, an iso-torque curve relating phase currents to torque and rotor position may be represented in any suitable tabular form including phase current values, torque values, and rotor position values. In fig. 6, the iso-torque curves correspond to 5 degrees of rotor electrical position, but it should be understood that the iso-torque curves may be generated by more than one rotor electrical position.

It should be noted that the generation of the iso-torque table described above may be repeatedly used for any given motor or family of motors (e.g., two or more motors having substantially the same operating characteristics, such as number of stator poles, number of rotor poles, air gap between stator and rotor poles, etc.). As such, the iso-torque tables described above may be generated for any suitable motor having any suitable predetermined operating characteristics, and the commutation schemes described herein with respect to aspects of the disclosed embodiments may be applied to any such suitable motor.

Referring again to fig. 1E, the controller 400 may include a position control loop (fig. 12 and 13), which will be described below, that may be configured to: the desired or otherwise predetermined amount of torque is specified at a given rotor electrical position and time. Any suitable commutation algorithm, such as the commutation algorithm described below, may detail the current in one of phases a-D. A table (such as the table generated above, a portion of which is shown in fig. 6) may be located in a memory accessible by controller 400 or included in controller 400 to provide controller 400 with corresponding currents for additional phases. For example, the commutation algorithm may specify the phase current i for phase A₁And the controller may be configured to obtain from the table the corresponding phase current i for phase B for any given torque and electrical angle of the rotor₂Thereby reducing torque ripple of the variable reluctance motor. FIG. 7 illustrates commutation for a conventional uncompensated torque ripple motor and a compensated torque ripple motor (example)As in accordance with aspects of the disclosed embodiments) an exemplary map of torque versus rotor position. As can be seen from fig. 7, compensating for torque ripple according to aspects of the disclosed embodiments (see curve 700) substantially reduces the effect of torque ripple (its nature comes from the mutual effect of adjacent phases being energized simultaneously, as evidenced in fig. 7, where the torque of the two curves is equal when only one phase is energized).

In accordance with aspects of the disclosed embodiments, referring again to fig. 1E and 1F and as described herein, the torque of the motor 100 may be a function of the motor position and the current of each phase. Also, there may not be a unique set of phase currents for a given torque (see, e.g., the table in fig. 6), which represents a substantially infinite number of combinations of possible phase current values to achieve a given torque. Referring also to fig. 8A, an example of phase current variation is shown for phase a and phase B of motor 100, for example, at constant torque. The spacing in the rotor positions is in the range of 0 to 15 degrees, only phase a and phase B are energized and the currents in phase C and phase D (see also fig. 4) are substantially zero. Here, since phase a drives the rotor 102, it may be referred to as a dominant phase, and phase B may be referred to as a latent phase, the current of phase B continuously increases or rises to drive the rotor as it moves between the stator poles 103P. When the rotor pole passes a given stator pole 103P, phase B becomes the dominant phase and phase a becomes the latent phase, so that the phase current in phase a decreases or falls. As can be seen from fig. 8A, in one aspect, the rise and/or fall of the phase current when driving the rotor 102 may be provided as a linear shape function so that the change in current is linear. In other respects, referring to fig. 8B, another possible scheme for varying the phase current is shown as a function of rotor position to produce a constant torque. Here, the rise and/or fall of the phase current is provided as a quadratic shape function. As can be realized, the rise and fall of the phase current can be provided as any suitable shape function. As can also be realized, the shape function for raising the phase current may be different from the shape function for lowering the phase current.

Still referring to fig. 4, 8A and 8B, as noted above, an example of the phase current change in phase a and phase B at constant torque is shown as the rotor 102 rotates from about 0 degrees to about 15 degrees. In other examples, the rotor may rotate between any suitable angle or arc. As also noted above, in this interval from about 0 degrees to between 15 degrees, the phase currents for phase C and phase D are substantially zero. In one aspect, the phase current signal may be periodic for the motor 100, approximately one cycle per 15 degrees of rotor rotation, and the phase current may be generated for rotor rotation intervals of about 0 degrees to about 15 degrees. As can be seen, in the about 0 to about 15 degree interval, phase a and phase B are active, and in the about 15 to about 30 degree interval, phase B and phase C are active, and so on. The profile of the current in phase B may be substantially similar to the profile shown for phase a in fig. 8A and 8B (e.g., in about 0 degree to about 15 degree intervals) over about 15 degree to about 30 degree intervals, and the profile of the phase current in phase C may be substantially similar to the profile shown for phase B in fig. 8A and 8B over about 15 degree to about 30 degree intervals. As can be realized, substantially the same periodic relationship applies to the other phase pairs B-C, C-D and D-A as the rotor rotates. In other aspects, any suitable periodic relationship may be provided for the phase pairs. In this aspect, at any given rotor position, up to two phases are active and at just about 15 degrees apart, with one phase becoming passive and the new phase becoming active.

In one aspect, the commutation schemes described herein may use one or more torque meters, such as the torque meter described above with reference to fig. 6, that produce motor torque as phase current i for any suitable motor interval (such as the about 0 degree to about 15 degree intervals mentioned above)_AAnd i_BAnd a function of motor position theta. In one aspect, the torque table may be analytically represented as:

wherein the torque T is position dependent. In other aspects, the torque table may be measured experimentally (e.g., as described above with reference to the torque curve generation station 510). In other aspects, the torque meter may be calculated by finite element analysis of a motor model, for example. In other aspects, the torque table may be generated in any suitable manner. It should be noted that although the commutation schemes described herein will be described with respect to the approximately 15 degree spacing mentioned above, in other aspects the commutation schemes described herein may be applied to any suitable spacing.

With reference to a periodicity of about 15 degrees (which may be any suitable interval in other aspects), the phase current i_AAnd i_BThe appropriate boundary conditions for (b) may be established as:

i _A=0 inθ=15 deg. [ 2]]

And

i _B=0 inθ=0 degree [3]

To solve for the two phase currents shown in, for example, fig. 3A and 3B, the approximately 15 degree interval may be divided generally into two halves or sub-intervals, one half being approximately 0 degrees to approximately 7.5 degrees and the other half being approximately 7.5 degrees to approximately 15 degrees. In each subinterval, one of the phase currents is defined by any suitable shape function, e.g. as described above, and the remaining phase currents may be determined from any suitable torque meter, e.g. such as shown in fig. 6.

Referring to fig. 9A and 9B, the total electrical power Pc consumed by energizing the phases (in this example, energizing phase a and phase B) is shown as a rotor rotating at any suitable number of revolutions (rpm), which in this example is about 60rpm for exemplary purposes. The power curve in fig. 9A corresponds to the phase current in fig. 8A, and the power curve in fig. 9B corresponds to the phase current in fig. 8B. Here, for exemplary purposes, a constraint may be placed on the available power of the motor such that the available power is about 540W. In other aspects, the power may be constrained to any suitable value, such as, for example, the rated power of the motor is commutated by the schemes described herein. The torque may be adjusted such that the peak power consumption falls below the approximately 540W power constraint. As can be seen in fig. 9A and 9B, at about 60rpm, the torque corresponding to a power constraint of about 540W is about 7.1 Nm for the linear shape function of fig. 8A and about 7.2 Nm for the quadratic shape function of fig. 8B in this example. It should be noted that in one aspect, the slope of the shape function may also be constrained, such as for the voltage of the bus supplying the phases as will be described below.

In one aspect of the disclosed embodiment, a method may be provided to detect a phase current that maximizes motor torque for a given limit of input power, where the shape function described above with reference to fig. 8A and 8B is replaced by a constraint on motor power consumption. In general, the voltage drop over a single phase of the motor can be written as:

wherein V is the voltage over the phase, i is the phase current, R is the phase resistance, and

is the flux linkage rate for the motor angular position theta and current i. Also, in the same manner as above,

where L (θ, i) is inductance. Thus, the voltage on the phase can be rewritten as:

and multiplying both sides of equation [6] by the current i yields the power equation:

thus, based on, for example, equation [7 ]]Can be directed to the phase current i_AAnd i_BPhase resistor R, and flux linkage

And

the constraints on motor power consumption or total power are written as:

wherein "

"denotes the mechanical power output of the motor (T is the motor torque andis the angular velocity),

and

represents resistive power loss in the motor winding or coil, and

and

representing the magnetic field energy stored in the motor. It should be noted that in one aspect, the torque may be specified by a motion analysis of the transport 111 (fig. 1), for example, as described in the following applications: international patent publication No. PCT/US2012/052977 entitled "Time-OptimalTracories for Robotic Transfer Devices" filed on 30/8/2012 and filed on 13/9/2012 (WO publication No. 2013/033289)U.S. patent application No. 13/614,007 entitled "Method for Transporting a subsystem with a subsystem Transport," the entire contents of which are incorporated herein by reference. In other aspects, torque (and/or angular velocity) may be obtained by motor sensors in real time, and power may be regulated by, for example, controller 400, such that the total power is substantially maintained at P_maxThe following is a description. Given the torque of the motor, the phase current i can be determined from the above described iso-torque table_AAnd i_B. In other aspects, the phase current may be determined in any suitable manner. In one aspect, equation [8 ] is constrained]Can be matched with an equal torque table and an equation [ 2]]And [3]Together determine the phase current i in a rotor position (or any other suitable rotor position) of, for example, about 0 degrees to about 15 degrees_AAnd i_B(or any other suitable phase current of the above-mentioned phase current pairs).

In another aspect of the disclosed embodiments, a method may be provided for determining a phase current that maximizes motor torque for a given limit of input power, wherein the shape function described above with reference to fig. 8A and 8B is represented by phase voltage V_busThe constraint above. For example, given equation [6] as above]The voltage on the phase described in (e.g., phase a and phase B in this example), then the constraint on the voltage in each phase can be written as:

and

wherein,

andmay be determined empirically from, for example, an iso-torque meter, a motor model, from motor sensors, or in any other suitable manner. In one aspect, equation [8 ] is constrained]Can be matched with an equal torque table and an equation [ 2]]And [3]Together determine the phase current i in a rotor position (or any other suitable rotor position) of, for example, about 0 degrees to about 15 degrees_AAnd i_B(or any other suitable phase current of the above-mentioned phase current pairs). In one aspect, the equation [9 ] is constrained]And [10 ]]Can be matched with an equal torque table and an equation [ 2]]And [3]Together determine the phase current i in a rotor position (or any other suitable rotor position) of, for example, about 0 degrees to about 15 degrees_AAnd i_B(or any other suitable phase current of the above-mentioned phase current pairs).

In one aspect of the disclosed embodiments, another commutation scheme can be provided in which a minimum power P is achieved_minAs described below. Here, the desired torque is known from a position control loop of the transport device 111 (fig. 1), for example, as mentioned above. Referring to fig. 10A and 10B, an iso-torque meter (which is substantially similar to the iso-torque meter described above) may be used to determine phase currents, such as i, for a given torque and motor rotor position in any suitable manner_AAnd i_B. For example, in one aspect, a unique set of phase currents i may be identified along a desired iso-torque line_AAnd i_B(see also fig. 6) to achieve minimum dissipated power in phase a and phase B. In other aspects, the minimum power P may be determined empirically, through numerical analysis, or the like_min. Once the minimum power is achieved, the corresponding phase current i for a given desired torque and at the respective rotor position may be_AAnd i_BSuch as, for example, in a table. Equation [9 ] above]And [10 ]]Can be used to verify: p for given torque and torque position_minAssociated phase current i_AAnd i_BCan be matched with the bus voltage V_busIs applied aboutAnd (4) bundling.

In another aspect of the disclosed embodiment, a real-time comparator commutation scheme can be used to operate the motor 100. For example, the controller 400 may include a current feedback loop that causes the coil inductance to change during real-time operation of the motor 100. The current feedback loop may allow for torque compensation that addresses the effects of torque ripple in the motor 100. For example, referring to fig. 12 and 13, the controller 400 may include a memory 400M, a position loop module 1200, a commutation loop module 1201, a current loop module, a torque ripple estimator, and an inductance model module. The motor 100 may include a motor phase system module 100M1 and a motor magnetic circuit system module 100M 2. Here, for example, the desired trajectory and actual state feedback are input into a position loop module 1200, which position loop module 1200 is configured to calculate the desired torque to be applied by the motor 100. The desired torque is input into a commutation loop module 1201, which commutation loop module 1201 may be configured to calculate a desired phase current to be applied in the motor 100 using the actual position and speed of the motor (as determined by, for example, motor sensors). The desired phase current is input into a current loop module 1202, which current loop module 1202 may use the actual phase current as feedback to calculate the phase voltage at the terminals of the respective coils 104 of the motor 100.

An inductance model module 1204 (where an inductance module may be represented as

) May be configured such that: resulting in a change in the inductance of the motor 100 with respect to, for example, the actual position and actual phase current of the motor, so that the current loop module can better utilize its control gain to achieve a more realistic inductance and better cope with the larger changes in inductance present in a variable inductance motor. As can be realized, the phase voltage generated by the current loop module 1202 may cause some torque ripple. To attenuate the torque ripple, a phase voltage correction signal may be applied to the phase voltage. The torque ripple estimator 1203 may use the estimated inductance, the actual phase current, the flux linkage rate, the actual phase current, and the actual phase currentOne or more of the actual position, the actual speed, and the desired torque are used to calculate, in real time, an appropriate phase voltage correction that will result in a reduction in torque ripple in the output of the motor magnetic circuit 100M2 when the actual torque is generated.

Flux-ramp rate (which can be written as

) The measurements may be made in any suitable manner, such as by using the sensor or coupling coil 1100 shown in fig. 11A and 11B, which may be located on or adjacent to the respective coil. In other aspects, the sensor 1100 may be located at any suitable location for measuring flux linkage. The sensor 1100 may be a stand-alone coil positioned such that: when phase coil 104 is energized (e.g., due to commutation), a flux linkage generated within stator pole 103P is induced in sensor 1100. The rate of change of the flux linkage with respect to resistance, current and termination voltage on coil 1100 is given by equation [4 ] above]And (4) limiting. By connecting the sensor 1100 to a high impedance path (such as an analog-to-digital converter or any other suitable high impedance path), the associated current can be ignored and the remainder is the termination voltage (see equation [11 ] below)]) The terminal voltage is substantially a direct measure of the rate of change of the flux linkage on the stator poles._，

Each motor phase may have its own sensor 1100, the sensor 1100 configured to provide a flux linkage rate for each rotor position.

It should be noted that the torque ripple compensation performed by the torque ripple estimator includes: the ability to indirectly measure the actual torque generated by the motor output. The indirect measurement of the actual torque is compared to the desired torque so that the torque ripple estimator can calculate a phase voltage correction that will bring the actual torque close to the desired torque. An indirect measurement of the actual torque can be derived from the following equation:

torque (b) = torquex

[12]

By using equation [12] and the flux linkage (see equation [5] above), an indirect measure of actual torque can be calculated from the following equation:

torque =

[13]

Wherein the flux linkage

Measured as described above (see equation [11 ]]) Inductance

Is determined empirically through the use of look-up tables, models, or in any other suitable manner, and expressionsMay be calculated from, for example, current and speed feedback or in any other suitable manner.

A synthetic phase current may be generated from the modified phase voltage (e.g., the modified phase voltage after the torque ripple estimator 1203 applies the phase voltage correction), which in turn may be used to generate the actual torque provided by the motor magnetic loop 100M 2. The inertial device 1205 (which may be substantially similar to the transporter 111 described above) reacts to the actual torque applied by generating the corresponding acceleration, velocity, and position of the inertial device 1205. The acceleration, velocity and position of the inertial device is then fed back to the appropriate control loop module as shown in fig. 12 and 13.

In aspects of the disclosed embodiments described herein, the torque-current-position relationship reflects: for example, under steady state conditions where the desired torque and rotor position are fixed in time, the motor torque is a function of the motor position and phase current. If the torque or rotor position changes over time, as is the case in robotic applications, the effectiveness of using the static torque relationship can be determined by the speed of response of the motor dynamics. The measure of motor dynamics is the torque step response speed of the motor. Fig. 14 shows the torque output of a brushless DC motor that commands a torque of about 3 Nm. The motor torque step response (e.g., dynamic response time) may be measured in any suitable manner. Fig. 14 also shows the torque step response of a variable reluctance motor (which has a similar form factor as a brushless DC motor). As can be seen from fig. 14 and 15, the brushless DC motor has a faster response time than the variable reluctance motor. It should be noted that the torque curve in a variable reluctance motor may begin at a substantially zero slope, while the torque curve on a brushless DC motor may begin at a non-zero slope. This is because the torque-current relationship is a quadratic relationship in the switched reluctance motor, and the torque-current relationship is a linear relationship in the brushless DC motor. Accordingly, it is expected that conventional switched reluctance motors may have an inherently low response time near zero current and torque compared to brushless DC motors. In one aspect of the disclosed embodiments, a system and method (such as may be embodied in a suitable algorithm) allows a switched reluctance motor to respond faster in a near zero torque/current range, as described further below. In accordance with aspects of the disclosed embodiments, the dynamic response of a variable reluctance motor may be improved as indicated next. The following equation is given:

wherein, T_VRMIs a variable (or, switched) reluctance motor torque, "i" is a phase current, "θ" is a rotor position, and "f (θ)" represents a dependence on the rotor position; then from equation [15 ]]It is appreciated that the dynamic response of a variable reluctance motor (such as motor 100) may be a function of phase current; variable reluctance motor (dT)_VRMDt) increases with increasing phase current; and when no current is passed through the coil 104 (fig. 1E and 1F), the dynamic response is substantially zero.

In this aspect of the disclosed embodiment, referring again to fig. 1E and 1F, the commutation scheme is to have a non-zero phase current at zero torque. The non-zero phase current may generate "bias torque" in other phases of the motor such that the dynamic response time of the motor increases (e.g., faster) (e.g., the gradient is between T =0, and the required torque T_demandChange). In a four-phase motor, such as motor 100, energizing two phases (the energized phases being determined by the motor position) produces torque in one direction, and energizing the remaining two phases produces torque in the opposite direction. Nominally, both phases are energized depending only on the direction of torque. Here, the commutation scheme energizes all four phases so that when the torque required by the motor is substantially zero, the positive torque due to the two phases a and B is balanced by the negative torque due to the remaining two phases C and D, and the net torque is zero. Energizing all four phases A-D in a balanced manner (e.g., such that the net torque is substantially zero or balanced) provides substantially non-zero current even in the zero-torque state of the motor 100 and improves the response time of the variable reluctance actuator (or effective bandwidth), as represented by equation [15 ]]What is stated.

As an example, if at a given motor position, phase a and phase B produce positive motor torque, and phase C and phase D produce negative motor torque, and the desired torque is T, and △ T is the selected offset torque compensation value, and the function f represents a torque-current-position relationship, the phase current may be defined as:

and

wherein i_A、i_B、i_CAnd i_DFIG. 16 illustrates a motor torque step response in response to a commanded torque of, for example, about 3 Nm for a brushless DC motor, a variable reluctance motor without phase current bias (basic VRM), a variable reluctance motor with constant phase current bias (e.g., when generating unbalanced torque (i.e., T T.sub.D.)_demand) When the bias does not substantially change with actuation of the motor), and variable reluctance motors with variable phase current bias (e.g., when generating unbalanced torque (i.e., T;)_demand) The bias changes with actuation of the motor). FIG. 16 shows response curves of desired torque for different motor configurations for comparison. The dashed portions in the figures represent an approximate representation of steady state operating conditions and are included for completeness and in other respects are not relevant to aspects of the features described herein. As can be seen in fig. 16, the response (rise) time of the variable reluctance motor with constant phase current bias is reduced more (i.e., faster response) than the basic VRM (without torque bias) and the response time of the variable reluctance motor with variable phase current bias is reduced more than the response time of the variable reluctance motor with constant phase current bias. To minimize the loss of motor power, the compensation torque may be set to a non-zero value as needed and determined by the application. In one aspect, a non-zero phase current may be applied so as toAt any appropriate time (e.g. within a predetermined time period or at a desired T_demandA predetermined time before the desired time of demand) generates a compensation torque (fig. 17, block 1700) (i.e., the compensation torque may be considered a pre-applied torque applied just before the demanded torque is demanded), rather than being applied in concert with the demanded torque. Also, as shown in fig. 16, a time-varying torque compensation curve may produce a faster dynamic response than a constant torque compensation. In one aspect, to make dynamic responses faster in, for example, robotic transport applications, a controller, such as controller 400, may be configured to: the bias torque is increased (e.g., set to a predetermined starting value) at or just before the beginning of movement of a robotic manipulator (such as transporter 111 in fig. 1E) (e.g., utilizing a pretorque command to produce a pretorque as described above) (fig. 17, block 1701), and the bias torque is decreased (e.g., reduced to a value less than the predetermined starting value) at the beginning of movement and/or before a desired or maximum torque and/or acceleration (e.g., acceleration of a substrate carried by the transporter) is reached (fig. 17, block 1702). This raising and lowering of the bias torque may substantially prevent or otherwise reduce any "overshoot" (e.g., movement beyond) of the robotic manipulator with respect to the desired pick or place target. In one aspect, the raising and lowering bias torque curves may be selected to be orders of magnitude shorter in duration than the movement duration of the robotic manipulator (e.g., the raising and lowering durations may be negligible compared to the duration of the robotic manipulator movement). In other aspects, the increase and decrease curves may have any suitable duration. In one aspect, the boost bias torque curve and the buck bias torque curve may have substantially zero slope at zero torque, and the boost duration and the buck duration may be determined by the available bus voltage and/or the motor coil inductance. As may be realized, the bias torque may be provided at more than one region of movement of the robotic manipulator (e.g., at the beginning of movement, at the end of movement, and/orAt one or more points between the start and end of the move). In one aspect, the increase in torque bias may be a gradual increase in bias torque. In another aspect, the drop in bias torque may depend on a desired dynamic response time.

As described above, the controller 400 (fig. 1E) may have a distributed architecture that includes high-level and low-level controllers similar to the controllers described in U.S. patent No. 7,904,182, the entire contents of which were previously incorporated herein by reference. In one aspect, the constant torque meter may be located in one or more high level controllers, such that aspects of the commutation scheme (which may include any suitable calculations, comparisons, sending commands to the variable reluctance motor, monitoring operating characteristics of the variable reluctance motor, altering the torque output of the motor, etc.) may be performed by one or more low level controllers.

As may be realized, aspects of the disclosed embodiments may be used alone or in any suitable combination.

In accordance with one or more aspects of the disclosed embodiments, a variable reluctance motor load mapping apparatus is provided. The apparatus comprises: a frame; an interface disposed on a frame configured for mounting a variable reluctance motor; a static load unit mounted to the frame and coupled to the variable reluctance motor; and a controller communicatively coupled to the static load unit and the variable reluctance motor. The controller is configured to: the method includes selecting at least one motor phase of the variable reluctance motor, energizing the at least one motor phase, and receiving motor operation data from at least the static load unit for mapping and generating a set of look-up tables of motor operation data.

In accordance with one or more aspects of the disclosed embodiments, the controller is configured to receive motor operation data from the static load unit and the variable reluctance motor, wherein the motor operation data includes at least one of a static motor torque, a respective phase current for each of at least the respective motor phases, and a motor rotor position.

In accordance with one or more aspects of the disclosed embodiment, the controller is configured to generate a constant torque value from the motor operation data as a function of the rotor position and the phase current of the adjacent motor phase.

In accordance with one or more aspects of the disclosed embodiment, the controller is configured to generate a minimum power value associated with each constant torque value and provide the minimum power values in a look-up table.

In accordance with one or more aspects of the disclosed embodiment, the controller is configured to generate a look-up table of motor operation data, wherein each look-up table of motor operation data comprises a collection of constant torque values and corresponding phase currents for a given rotor position.

In accordance with one or more aspects of the disclosed embodiments, the controller is configured to, for a batch of predetermined rotor positions corresponding to each predetermined rotor position, energize adjacent motor phases at a batch of predetermined current combinations, and receive a resultant static torque for each predetermined current combination from the static load unit.

In accordance with one or more aspects of the disclosed embodiment, the controller is configured to vary the additional motor phase current or any suitable combination of the additional phase currents for each of the predetermined rotor positions and the predetermined first motor phase currents.

In accordance with one or more aspects of the disclosed embodiment, the controller is configured to generate a torque value from the resultant static torque, and map the torque value and associated phase current combination for each predetermined rotor position to form a set of motor operation data look-up tables.

In accordance with one or more aspects of the disclosed embodiments, a method is provided for characterizing a relationship between torque, current, and position of a motor load that determines a variable reluctance motor. The method comprises the following steps: providing a static load unit; coupling a variable reluctance motor to a static load unit; selecting at least one motor phase of the variable reluctance motor; energizing the at least one motor phase; receiving motor operation data from at least one static load unit by using a controller; and drawing and generating a plurality of look-up tables of motor operation data by using the controller.

In accordance with one or more aspects of the disclosed embodiment, the method further comprises: receiving, by using the controller, motor operation data from the static load unit and the variable reluctance motor, wherein the motor operation data includes at least one of a static motor torque, a respective phase current for each of at least the respective motor phases, and a motor rotor position.

In accordance with one or more aspects of the disclosed embodiments, the method comprises: a constant torque value is generated from the motor operation data as a function of the phase current and the rotor position by using a controller.

In accordance with one or more aspects of the disclosed embodiment, each motor operation data look-up table comprises: a set of constant torque values and corresponding phase currents for a given rotor position.

In accordance with one or more aspects of the disclosed embodiments, the method comprises: the motor phases at a set of predetermined current combinations for a set of predetermined rotor positions are energized by using a controller, and a resultant static torque for each of the predetermined current combinations and corresponding rotor positions is received from a static load unit.

In accordance with one or more aspects of the disclosed embodiments, the method comprises: the additional motor phase currents are varied for each predetermined motor position and predetermined first motor phase current by using the controller.

In accordance with one or more aspects of the disclosed embodiments, the method comprises: a torque value is generated from the resultant static torque by using a controller, and the associated phase current combination for each predetermined rotor position and the torque value are plotted to form a set of motor operation data look-up tables.

In accordance with one or more aspects of the disclosed embodiments, a method comprises: coupling a load to an output shaft of the variable reluctance motor; generating a batch of static torque on an output shaft by using a variable reluctance motor; adjusting a rotor position of the variable reluctance motor; and recording motor data including static torque values, rotor positions, and phase currents of adjacent phases of the variable reluctance motor by using the controller.

In accordance with one or more aspects of the disclosed embodiments, a batch of phase current combinations is recorded for adjacent phases of each static torque value in a batch of static torques.

In accordance with one or more aspects of the disclosed embodiments, a batch of static torque is generated for each rotor position in a batch of rotor positions.

In accordance with one or more aspects of the disclosed embodiments, the method comprises: a data look-up table is formed by using the controller to plot a set of static torques and corresponding phase current combinations for each rotor position.

In accordance with one or more aspects of the disclosed embodiments, the method comprises: the motor phases at a set of predetermined current combinations for a set of predetermined rotor positions are energized using a controller, and the resultant static torque for each of the predetermined current combinations and corresponding rotor positions is recorded.

In accordance with one or more aspects of the disclosed embodiments, an electric machine is provided. The brushless motor includes: a passive rotor having at least one rotor pole; a stator having at least one stator pole and a phase coil associated with each of the at least one stator pole, the phase coil configured to establish flux in a magnetic circuit located between the rotor and the stator, wherein the rotor and the stator define a predetermined motor form factor; and a controller configured to control the current to each phase coil to generate a predetermined rotor torque, the controller programmed with at least a predetermined constant torque value and an associated phase current value, such that the controller determines the current for each phase coil to generate the required rotor torque based on the predetermined constant torque value and the associated phase current value.

In accordance with one or more aspects of the disclosed embodiment, the predetermined constant torque value and the associated phase current value are empirically generated values.

In accordance with one or more aspects of the disclosed embodiment, the predetermined constant torque values and associated phase current values of the brushless motor are generated from a system modeling analysis including one of a numerical modeling analysis or a finite element analysis.

In accordance with one or more aspects of the disclosed embodiments, a brushless motor includes a variable reluctance motor in either a rotary configuration or a linear configuration.

In accordance with one or more aspects of the disclosed embodiments, a brushless electric machine includes a variable reluctance motor configured to operate in a vacuum environment.

In accordance with one or more aspects of the disclosed embodiment, the passive rotor is a coil-less and magnet-less rotor.

In accordance with one or more aspects of the disclosed embodiment, the associated phase current value is a batch of phase current values, such that each phase current vector produces a predetermined constant torque value that is common to the batch of phase current values.

In accordance with one or more aspects of the disclosed embodiment, the controller is programmed with a minimum power value associated with each predetermined constant torque value.

In accordance with one or more aspects of the disclosed embodiments, the predetermined constant torque value and associated power and phase current values are commutatable for each motor having a form factor similar to the predetermined motor form factor.

In accordance with one or more aspects of the disclosed embodiment, the correlated phase current values are pre-measured current values.

In accordance with one or more aspects of the disclosed embodiments, the constant torque values and associated phase current values form one or more commutation tables relating torque, rotor position, and phase current strength of the motor phases.

In accordance with one or more aspects of the disclosed embodiments, a variable reluctance motor controller is provided. The controller includes: one or more sensors configured to measure predetermined operating characteristics of the variable reluctance motor; a current loop module configured to provide a phase voltage to the variable reluctance motor; and a torque ripple estimator configured to generate a substantially real-time phase voltage correction signal based on predetermined operating characteristics and apply the real-time phase voltage correction signal to the phase voltage so as to attenuate a torque ripple effect of the variable reluctance motor.

In accordance with one or more aspects of the disclosed embodiment, the predetermined operational characteristics include: one or more of motor rotor position, motor rotor angular velocity, phase current per motor phase, flux linkage rate, and inductance per phase.

In accordance with one or more aspects of the disclosed embodiments, the flux turn-chain rate is determined from a measurement.

In accordance with one or more aspects of the disclosed embodiments, one or more sensors comprise: a coupling coil at or adjacent each motor phase coil configured to measure a flux linkage associated with the respective motor phase coil.

In accordance with one or more aspects of the disclosed embodiment, the inductance is an estimated inductance obtained by the controller from a look-up table or a motor model.

In accordance with one or more aspects of the disclosed embodiments, a variable reluctance motor controller includes an inductance module configured to determine a change in inductance of a motor relative to a motor rotor position and phase current.

In accordance with one or more aspects of the disclosed embodiments, the torque ripple estimator includes a real-time comparator between the desired motor torque and the actual motor torque such that the phase voltage correction signal causes the actual motor torque to approach the desired motor torque.

In accordance with one or more aspects of the disclosed embodiments, a brushless motor is provided. The brushless motor includes: a passive rotor having at least one rotor pole; a stator having at least one stator pole and a phase coil associated with each of the at least one stator pole, the phase coil configured to establish flux in a magnetic circuit located between the rotor and the stator, wherein the rotor and the stator define a predetermined motor form factor; and a controller configured to control the current to each phase coil so as to generate a predetermined rotor torque, the controller programmed to provide a non-zero phase current to each phase coil at a zero-torque motor output.

In accordance with one or more aspects of the disclosed embodiment, the non-zero phase current provided to each phase coil achieves a net torque substantially equal to zero.

In accordance with one or more aspects of the disclosed embodiments, the non-zero phase current enables a reduction in the dynamic response time (i.e., an increase in response speed) of the brushless motor.

It is to be understood that the above description is only illustrative of aspects of the disclosed embodiments. Various alternatives and modifications can be devised by those skilled in the art without departing from aspects of the disclosed embodiments. Accordingly, aspects of the disclosed embodiments are intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims. Further, the different features recited in mutually different dependent claims or in the independent claims do not indicate that a combination of these features, which is included in the scope of aspects of the invention, may not be used to advantage.

Claims

1. A brushless electric machine, comprising:

a passive rotor having at least one rotor pole;

a stator having at least one stator pole and a phase coil associated with each of the at least one stator pole;

wherein the phase coils are configured to establish flux in a magnetic circuit between the rotor and stator, wherein the rotor and stator define a predetermined motor form factor; and

a controller configured to control current flow to each phase coil to generate a predetermined rotor torque, the controller programmed with at least a predetermined constant torque value and a phase current value for each phase coil corresponding to a predetermined constant torque value combination and a corresponding combination of adjacent phase coils, such that the controller determines a current for each phase coil generating a required rotor torque based on the predetermined constant torque value and the phase current value for each phase coil and the corresponding combination of adjacent phase coils.

2. The brushless electric machine of claim 1, wherein the predetermined constant torque values and associated phase current values are empirically generated values.

3. The brushless electric machine of claim 1, wherein the predetermined constant torque values and associated phase current values of the brushless electric machine are generated from a system modeling analysis comprising one of a numerical modeling analysis or a finite element analysis.

4. The brushless electric machine of claim 1, further comprising a variable reluctance motor of either a rotary or linear configuration.

5. The brushless electric machine of claim 1, further comprising a variable reluctance motor configured to operate in a vacuum environment.

6. The brushless electric machine of claim 1, wherein the passive rotor is a non-coil and non-magnet rotor.

7. The brushless electric machine of claim 1, wherein the associated phase current values are a batch of phase current values, such that each phase current vector produces a predetermined constant torque value common to the batch of phase current values.

8. The brushless electric machine of claim 1, wherein the controller is programmed with a minimum power value associated with each of the predetermined constant torque values.

9. The brushless electric machine of claim 8, wherein the predetermined constant torque value and associated power and phase current values are commutative for each electric machine having a similar form factor as the predetermined electric machine form factor.

10. The brushless electric machine of claim 1, wherein the correlated phase current values are pre-measured current values.

11. The brushless electric machine of claim 1, wherein the constant torque values and associated phase current values form one or more commutation tables relating phase current strengths to torque, rotor position, and motor phase.

12. A brushless electric machine, comprising:

a passive rotor having at least one rotor pole;

a controller configured to control current to each phase coil so as to generate a predetermined rotor torque, the controller programmed to provide a non-zero phase current to each phase coil at a zero-torque motor output.

13. The brushless electric machine of claim 12, wherein the non-zero phase current provided to each phase coil achieves a net torque substantially equal to zero.

14. The brushless electric machine of claim 12, wherein the non-zero phase current enables a reduction in a dynamic response time of the brushless electric machine.

15. A variable reluctance motor load mapping apparatus, comprising:

a frame;

an interface disposed on a frame configured for mounting a variable reluctance motor;

a static load unit mounted to the frame and coupled to the variable reluctance motor; and

a controller communicatively coupled to the static load unit and the variable reluctance motor, the controller configured to: selecting at least one motor phase of the variable reluctance motor, energizing the at least one motor phase, and recording, using the controller, a static motor torque at a static load unit corresponding to a segment of the at least one motor phase to characterize a relationship between values of the static motor torque with respect to a motor rotor position and a corresponding phase current of one of the selected at least one motor phase of the variable reluctance motor in operation.

16. The apparatus of claim 15, wherein at least the static load unit generates motor operation data comprising at least one of static motor torque, respective phase current for each at least one respective motor phase, and motor rotor position for mapping and generating a motor operation data look-up table.

17. The apparatus of claim 16 wherein the controller receives motor operation data from at least a static load unit for mapping and generating a look-up table of motor operation data.

18. The apparatus of claim 15, wherein the controller is configured to receive motor operation data from the static load unit and the variable reluctance motor, wherein the motor operation data comprises at least one of a static motor torque, a respective phase current for each at least one respective motor phase, and a motor rotor position.

19. The apparatus of claim 15 wherein the controller is configured to generate a constant torque value from the motor operation data as a function of the motor rotor position and the phase current of the adjacent motor phase.

20. The apparatus of claim 19 wherein the controller is configured to generate a minimum power value associated with each constant torque value and provide the minimum power values in a look-up table.

21. The apparatus of claim 15 wherein the controller is configured to generate a look-up table of motor operation data, wherein each look-up table of motor operation data comprises a collection of constant torque values and corresponding phase currents for a given rotor position.

22. The apparatus of claim 15 wherein the controller is configured to energize adjacent motor phases at a range of predetermined current combinations for a range of predetermined motor rotor positions corresponding to each motor predetermined rotor position, and to receive a resultant static torque for each of the predetermined current combinations from the static load unit.

23. The apparatus of claim 22, wherein the controller is configured to vary the additional motor phase current or any suitable combination of additional phase currents for each predetermined motor rotor position and predetermined first motor phase current.

24. The apparatus of claim 22 wherein the controller is configured to generate torque values from the resultant static torque and plot the torque values and associated phase current combinations for each predetermined motor rotor position to form a batch of motor operation data look-up tables.

25. A variable reluctance motor controller, the controller comprising:

one or more sensors configured to measure predetermined operating characteristics of the variable reluctance motor;

a current loop module configured to provide a phase voltage to the variable reluctance motor; and

a torque ripple estimator configured to generate a substantially real-time phase voltage correction signal based on predetermined operating characteristics and to apply the substantially real-time phase voltage correction signal to the phase voltage in order to attenuate a torque ripple effect of the variable reluctance motor.

26. A variable reluctance motor controller according to claim 25, wherein the predetermined operating characteristics include: one or more of motor rotor position, motor rotor angular velocity, phase current per motor phase, flux linkage rate, and inductance per phase.

27. The variable reluctance motor controller of claim 26 wherein the flux linkage rate is determined from a measured value.

28. The variable reluctance motor controller of claim 26 wherein the inductance is an estimated inductance obtained by the controller from a look-up table or a motor model.

29. A variable reluctance motor controller according to claim 25, wherein the one or more sensors comprise: a coupler coil disposed at or adjacent each motor phase coil, the coupler coil configured to measure a flux linkage associated with the respective motor phase coil.

30. The variable reluctance motor controller of claim 25 further comprising an inductance module configured to determine a change in inductance of the motor relative to the motor rotor position and phase current.

31. The variable reluctance motor controller of claim 25 wherein the torque ripple estimator comprises a real time comparator between the desired motor torque and the actual motor torque such that the phase voltage correction signal causes the actual motor torque to approach the desired motor torque.

32. A method for characterizing a relationship between determining a torque, a current, and a position of a motor load of a variable reluctance motor, the method comprising:

providing a static load unit;

coupling a variable reluctance motor to a static load unit;

selecting at least one motor phase of the variable reluctance motor;

energizing the at least one motor phase;

receiving, using a controller, motor operation data from at least a static load unit; and

the controller is used to map and generate a set of look-up tables of motor operation data.

33. The method of claim 32, further comprising receiving, using the controller, motor operation data from the static load unit and the variable reluctance motor, wherein the motor operation data comprises at least one of a static motor torque, a respective phase current for each of at least the respective motor phases, and a motor rotor position.

34. The method of claim 33, further comprising generating a constant torque value from the motor operation data as a function of the phase current and the rotor position using the controller.

35. The method of claim 32 wherein the controller is configured to generate a minimum power value associated with each constant torque value and provide the minimum power values in a look-up table.

36. The method of claim 32, wherein each motor operation data look-up table comprises: a set of constant torque values and corresponding phase currents for a given rotor position.

37. The method of claim 32, further comprising energizing motor phases at a set of predetermined current combinations for a set of predetermined rotor positions using a controller and receiving a resultant static torque from the static load unit for each of the predetermined current combinations and corresponding rotor positions.

38. The method of claim 37, further comprising varying, using the controller, the additional motor phase currents for each of the predetermined rotor position and the predetermined first motor phase currents.

39. The method of claim 37 further comprising generating a torque value from the composite static torque using the controller and plotting the associated phase current combination and the torque value for each predetermined rotor position to form a set of motor operation data look-up tables.

40. A method for a brushless motor, the method comprising:

providing a passive rotor having at least one rotor pole;

providing a stator having at least one stator pole and a phase coil associated with each of the at least one stator pole;

establishing flux in a magnetic circuit between the rotor and a stator using the phase coils, wherein the rotor and stator define a predetermined motor form factor; and

controlling the current to each phase coil with a controller to generate a predetermined rotor torque, the controller programmed with at least a predetermined constant torque value and a phase current value for each phase coil corresponding to a predetermined constant torque value combination and a corresponding combination of adjacent phase coils, such that the controller determines the current for each phase coil generating the required rotor torque based on the predetermined constant torque value and the phase current value for each phase coil and the corresponding combination of adjacent phase coils.

41. The method of claim 40, wherein the predetermined constant torque value and associated phase current value are empirically generated values.

42. The method of claim 40, wherein the predetermined constant torque values and associated phase current values of the brushless motor are generated from a system modeling analysis including one of a numerical modeling analysis or a finite element analysis.

43. The method of claim 40, wherein the brushless electric machine comprises a rotary or linear configured variable reluctance motor.

44. The method of claim 40, wherein the brushless electric machine comprises a variable reluctance motor configured to operate in a vacuum environment.

45. The method of claim 40, wherein the passive rotor is a non-coil and non-magnet rotor.

46. The method of claim 40, wherein the associated phase current value is a batch of phase current values, such that each phase current vector produces a predetermined constant torque value that is common to the batch of phase current values.

47. The method of claim 40, wherein the controller is programmed with a minimum power value associated with each of the predetermined constant torque values.

48. The method of claim 47 wherein the predetermined constant torque value and associated power and phase current values are reversible for each motor having a form factor similar to the predetermined motor form factor.

49. The method of claim 40, wherein the correlated phase current values are pre-measured current values.

50. The method of claim 40, wherein the constant torque values and associated phase current values form one or more commutation tables relating phase current strengths to torque, rotor position, and motor phase.

51. A method for a brushless motor, the method comprising:

providing a passive rotor having at least one rotor pole;

establishing flux in a magnetic circuit between the rotor and a stator using phase coils, wherein the rotor and stator define a predetermined motor form factor; and

the current to each phase coil is controlled using a controller programmed to provide a non-zero phase current to each phase coil at the zero torque motor output in order to generate a predetermined rotor torque.

52. The method of claim 51, wherein the non-zero phase current provided to each phase coil achieves a net torque substantially equal to zero.

53. The method of claim 51, wherein the non-zero phase current effects a reduction in a dynamic response time of the brushless motor.