IPR2015-00762 - EXHIBIT 1010
`
`Zhongshan Broad Ocean Motor Co., Ltd., Petitioner
`
`Nidec Motor Corporation, Patent Owner
`
`1
`
`

`

`US 7,342,379 B2
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`Page 2
`
`US. PATENT DOCUMENTS
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`5,495,162 A
`5,498,945 A
`5569994 A
`5,635,810 A
`5,736,823 A
`5,747,971 A
`5,789,893 A
`5,801,935 A
`5,854,547 A
`5,903,128 A
`5929590 A
`5953491 A
`6,005,364 A
`6081093 A
`6,137,258 A
`6,232,692 B1
`6,278,256 B1
`6,297,621 B1
`6,304,052 B1
`6,326,750 B1
`6,362,586 B1
`6,369,536 B2
`6,404,154 B2
`6,433,506 B1
`6,441,580 B2
`6,443,873 B2
`6,462,491 B1
`6,515,395 Bl
`6,515,442 131*
`6,567,282 Bl
`6,586,904 B2
`6,603,226 Bl
`6,628,099 B2
`6,661,194 B2
`6,690,137 B2
`
`2/1996 Rozman etal.
`3/1996 Prakash
`10/1996 Taylor et al~
`6/ 1997 G061
`4/1998 Nordby etal.
`5/1998 Roman etal
`8/1998 Watkins
`9/1998 Sugden etal.
`12/1998 Nakazawa
`5/1999 Sakakibara etal.
`7/1999 Tang
`9/1999 Searsetal
`12/ 1999 Acarnley
`60000 Oguro etal.
`10/2000 Jansen
`5/2001 Kliman
`8/2001 Aoyama
`10/2001 Hui et al.
`10/2001 O’Meara et al.
`12/2001 Marcinkiewicz
`3/2002 Naidu
`4/2002 Beifus et al.
`6/2002 MarcinkieWicz
`8/2002 Pavlov et a1.
`8/2002 MarcinkieWicz
`9/2002 Suzuki
`10/2002 Iijima et al.
`2/2003 Jansen
`2/2003 Okubo et a1.
`5/2003 KikUChi 6t 31.
`7/2003 McClelland et 3L
`8/2003 Liang et 3L
`9/2003 Iwaji et a1.
`12/2003 Zaremba et al.
`2/2004 Iwaji et al.
`
`............... 318/560
`
`6,696,812 B2
`6,731,083 B2
`6,750,626 B2
`6,756,753 B1
`6,756,757 B2
`6,791,293 B2
`6,801,012 B1
`6,828,751 B2
`6,831,439 B2
`6,874,221 B2
`6,879,124 B1
`6,883,333 B2
`6,894,454 B2
`7,084,591 B2
`7,095,131 B2
`2003/0163226 A1*
`
`2/2004 Kaneko et al.
`5/2004 Marcinkiewicz
`6/2004 Leonardietal.
`6/2004 Marcinkiewicz etal.
`6/2004 Marcinkiewicz et al.
`9/2004 Kaitani
`10/2004 Islam etal.
`12/2004 Sadasivam etal.
`12/2004 Won etal.
`4/2005 Jansen etal.
`4/2005 Jiang etal.
`4/2005 Shearer et al.
`5/2005 Patel et al.
`8/2006 Kobayashietal.
`8/2006 Mikhail et al.
`8/2003 Tan ............................... 701/1
`
`OTHER PUBLICATIONS
`
`“An AC Motor Closed Loop Performances With Different Rotor
`Flux Observers”, M. Alexandru, R. Bojoi, G. Ghelardi and SM.
`Tenconi; pp. 1-7; prior to Jun. 24, 2005.
`“Indirect Rotor-Position Estimation Techniques For Switched
`Reluctance MotorsiA Review”; Iqbal Hussain; pp. 1-15; prior to
`Jun. 24, 2005.
`“Lecture 9: State Observer And Output Feedback Controller”; pp.
`1-14; May 16, 2005.
`“Sensorless Motor Control Method For Compressor Applications”;
`Yashvant Jani; pp. 1-23; Mar. 29, 2005.
`“Energy Conversion and Transport”; George G. Karady and Keith
`Holbert; Chapter 9, Introduction to Motor Control And Power
`Electronics; EE360; pp. 1-37; prior to Jun. 24, 2005.
`“Minimum Error Entropy Luenberger Observer”; Jian-Wu Xu,
`Deniz Erdogmus and Jose C. Principe; pp. 1-13; prior to Jun. 24,
`2005.
`
`* cited by examiner
`
`2
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`

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`U.S. Patent
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`Diar.11,2008
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`Sheetl,of13
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`U.S. Patent
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`Mar. 11, 2008
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`Sheet 2 of 13
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`U.S. Patent
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`Mar. 11, 2008
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`U.S. Patent
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`Mar. 11,2008
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`Sheet 4 of 13
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`

`

`U.S. Patent
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`Diar.11,2008
`
`Sheet5 0f13
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`US 7,342,379 B2
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`U.S. Patent
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`Mar. 11,2008
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`Sheet 7 of 13
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`US 7,342,379 B2
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`71 6
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`states
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`HS. 7
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`9
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`

`

`U.S. Patent
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`Mar. 11, 2008
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`Sheet 8 0f 13
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`US 7,342,379 B2
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`800
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`FIG. 8
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`

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`U.S. Patent
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`Mar. 11, 2008
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`Sheet 11 0f 13
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`US 7,342,379 B2
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`U.S. Patent
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`Diar.11,2008
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`U.S. Patent
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`Mar. 11, 2008
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`Sheet13 of13
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`US 7,342,379 B2
`
`1
`SENSORLESS CONTROL SYSTEMS AND
`METHODS FOR PERMANENT MAGNET
`ROTATING MACHINES
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`5
`
`This application claims the benefit of US. Provisional
`Applications No. 60/694,077 and No. 60/694,066 filed Jun.
`24, 2005, the entire disclosures of which are incorporated 10
`herein by reference.
`
`FIELD OF THE INVENTION
`
`invention relates generally to control of 15
`The present
`rotating machines, including but not limited to sensorless
`control of permanent magnet rotating machines.
`
`BACKGROUND OF THE INVENTION
`
`20
`
`Permanent magnet machines, such as brushless perma-
`nent magnet motors, have been conventionally provided
`with position sensing devices. Such devices indicate, for use
`in controlling the motor, the rotor position with respect to the
`stator. However, rotor position sensors can be quite expen- 25
`sive, occupy space within a motor housing, and sometimes
`fail. To eliminate the need for position sensors, various
`“sensorless” motor constructions and methods have been
`
`developed with varying degrees of success. As recognized
`by the present inventors a need exists for improvements in 30
`sensorless control systems for rotating permanent magnet
`machines.
`
`SUMMARY OF THE INVENTION
`
`35
`
`invention, a method is
`In one aspect of the present
`provided for controlling a permanent magnet
`rotating
`machine. The machine includes a stator having a plurality of
`energizable phase windings situated therein, a rotor situated
`to rotate relative to the stator, and an estimator having at 40
`least one gain value and employing an observer. The method
`includes varying the gain of the estimator as a function of
`either a demanded rotor speed or an estimated rotor speed to
`thereby position poles of the observer at desired locations.
`In another aspect of the invention, a method is provided 45
`for controlling a permanent magnet rotating machine. The
`machine includes a stator having a plurality of energizable
`phase windings situated therein, and a rotor situated to rotate
`relative to the stator. The method includes determining a
`value of Idr-axis current to be injected, and selecting a value 50
`of IQr-axis current that, in conjunction with the value of
`Idr-axis current, will produce a desired rotor torque.
`In still another aspect of the invention, a method is
`provided for controlling a permanent magnet
`rotating
`machine. The machine includes a stator having a plurality of 55
`energizable phase windings situated therein, and a rotor
`situated to rotate relative to the stator. The method includes
`
`receiving energization feedback from the machine, and
`producing a flux estimate compensated for saturation in the
`stator.
`
`60
`
`Further aspects of the present invention will be in part
`apparent and in part pointed out below. It should be under-
`stood that various aspects of the invention may where
`suitable be implemented individually or in combination with
`one another. It should also be understood that the detailed 65
`
`description and drawings, while indicating certain exem-
`plary embodiments of the invention, are intended for pur-
`
`2
`
`poses of illustration only and should not be construed as
`limiting the scope of the invention.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a block diagram of a rotating permanent magnet
`(PM) machine system according to one exemplary embodi-
`ment of the invention.
`
`FIG. 2 is a block diagram of a PM machine system
`configured to operate primarily in a torque control mode
`according to another exemplary embodiment of the inven-
`tion.
`
`FIG. 3 is a block diagram of a PM machine system
`configured to operate primarily in a speed control mode
`according to another exemplary embodiment of the inven-
`tion.
`
`FIG. 4 is a graph illustrating how gain values can be
`varied with respect to rotor speed so as to maintain the poles
`of an observer employed by the estimators of FIGS. 2 and
`3 in desired locations.
`
`FIGS. 5a and 5b illustrate how estimator gain values
`approach excessive values as the rotor speed approaches
`zero.
`
`FIG. 6 is a block diagram illustrating how estimator gain
`values can be stored in and accessed from lookup tables.
`FIG. 7 is a flow diagram of a method implemented by the
`gain schedulers of FIGS. 2 and 3 according to another
`exemplary embodiment of the invention.
`FIG. 8 is a flow diagram of a method of calculating a
`Qr-axis current based on a given dr-axis current injection to
`produce a desired rotor torque according to another exem-
`plary embodiment of the invention.
`FIG. 9 is a block diagram of a speed loop controller, a
`torque to Ier Map block, and a Idr injection block accord-
`ing to another exemplary embodiment of the invention.
`FIG. 10 is a block diagram of the torque and Idr to IQr
`map block of FIG. 9 according to another exemplary
`embodiment.
`
`FIG. 11 is a block diagram illustrating how saturation
`effects can be compensated for in the measurement path of
`an observer according to another exemplary embodiment.
`FIG. 12(a) is graph illustrating how two energization
`feedback samples are collected at the beginning and end of
`an exemplary sampling interval according to the prior art.
`FIG. 12(b) is a graph illustrating how two energization
`feedback samples can be collected and averaged to produce
`an estimated rotor position/angle according to another
`embodiment of the invention.
`
`FIG. 13 is a block diagram of an exemplary speed trim
`mechanism for producing a speed trim value that can be
`provided to the estimator of FIG. 3 according to another
`exemplary embodiment of the invention.
`Like reference symbols indicate like elements or features
`throughout the drawings.
`
`DETAILED DESCRIPTION OF EXEMPLARY
`EMBODIMENTS
`
`Illustrative embodiments of the invention are described
`
`below. In the interest of clarity, not all features of an actual
`implementation are described in this specification. It will be
`appreciated that in the development of any actual embodi-
`ment, numerous implementation-specific decisions must be
`made to achieve specific goals, such as performance objec-
`tives and compliance with system-related, business-related
`and/or environmental constraints. Moreover,
`it will be
`appreciated that such development efforts may be complex
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`US 7,342,379 B2
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`3
`and time-consuming, but would nevertheless be a routine
`undertaking for those of ordinary skill in the art having the
`benefit of this disclosure.
`
`FIG. 1 illustrates a rotating permanent magnet machine
`system 100 according to one embodiment of the present
`invention. The machine system 100 includes a rotating
`permanent magnet electric machine 101, such as a perma-
`nent magnet alternating current (PMAC) motor or a hybrid
`permanent magnet/switched reluctance (PM/SR) motor. For
`simplicity, the term “motor” is often used in this specifica-
`tion. However, one skilled in the art having the benefit of this
`disclosure will understand that
`the present
`invention is
`applicable to other types of rotating electric machines,
`including generators. The PM machine 101 shown in FIG. 1
`includes a stationary component (stator) 102 and a rotating
`component (rotor) 104. The machine 101 can have an inner
`rotor or an outer rotor construction.
`In this exemplary
`embodiment, the PM machine 101 is a three phase machine
`having an inner rotor construction with energizable phase
`windings 106A, 106B, 106C wound about the stator 102,
`which are energized through the application of electric
`power to the motor terminals.
`A drive 108 is coupled to the terminals of the machine for
`providing electric power. The drive 108 receives control
`inputs from a controller 110 that receives energization
`feedback 112 from the machine (such as the currents and/or
`voltages at the motor terminals), or that assumes the actual
`voltage supplied to the motor is that which was demanded by
`the controller 110 (e.g., in the form of PWM duty cycle),
`from which the electrical angle and electrical speed can be
`determined (i.e., estimated sensorlessly). From these esti-
`mates, rotor speed can be inferred, as can rotor angle (to the
`extent the estimates are based upon electrical angle). The
`controller 110 of FIG. 1 is shown as receiving an input
`demand 114 that may be, for example, a torque demand or
`a speed demand.
`While the drive 108 of FIG. 1 is illustrated in exemplary
`form as energizing three power terminals of a three phase
`machine 101, it should be understood that more or fewer
`power terminals may be provided to accommodate machines
`with greater or less than three phases, or if various types of
`inverters (e.g., with neutral connections) are used. The drive
`may be of conventional design and configured to provide,
`for example., sine wave excitation to the motor terminals or
`square wave excitation using conventional pulse width
`modulation (PWM) excitation.
`FIG. 2 illustrates additional details of the system of FIG.
`1 as configured to operate primarily in a torque control
`mode. For this reason, a torque demand input 214 is shown
`in FIG. 2. The torque demand input may be received directly
`by the system 200 as an external command or alternatively,
`may be derived from an external command. For example,
`the torque demand input may be derived from a speed
`demand input or from an air flow demand input (e.g., where
`the system of FIG. 2 is embodied in an air handler/blower for
`a climate control system). Additional details regarding the
`embodiment of FIG. 2 are provided in U.S. application Ser.
`No. ll/293,743 filed on Dec. 2, 2005] titled Control Systems
`and Methods for Permanent Magnet Rotating Machines and
`filed [on even date herewith], the entire disclosure of which
`is incorporated herein by reference.
`FIG. 3 illustrates additional details of the system of FIG.
`1 as configured to operate primarily in a speed control mode.
`Further information regarding operating in speed control
`modes is set forth in U.S. Pat. No. 6,756,753.
`Described below are several additional improvements in
`controlling a PM machine according to various aspects of
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`the present invention. It should be understood that each
`improvement can be advantageously implemented by itself
`or in combination with one or more other improvements
`disclosed herein.
`
`As shown in FIGS. 2 and 3, the controller of FIG. 1 can
`include an estimator 202, 302 for estimating the machine’s
`electrical speed and angle. In some embodiments, the esti-
`mators 202, 302 employ a Luenberger Observer. However,
`other types of observers, including the Kalman Estimator,
`may be employed.
`According to one aspect of the present invention, the gain
`of an estimatorisuch as the estimators 202, 302 shown in
`FIGS. 2 and 34can be varied (e.g., using the gain sched-
`ulers 204, 304 shown in FIGS. 2 and 3) as a function of
`either a demanded rotor
`speed (including a
`filtered
`demanded speed) or an estimated rotor speed. In this man-
`ner, control system poles (i.e., poles of the observer) can be
`positioned at desired locations, including maintaining the
`poles at desired and not necessarily fixed locations to
`improve control system and machine stability.
`there is no
`In a torque control mode of operation,
`demanded speed. Therefore, the estimator gains are prefer-
`ably varied as a function of the estimated rotor speed so as
`to position the control system poles at desired locations. The
`estimated rotor speed used in the gain scheduling may be
`pre-processed in a suitable manner before being used in the
`gain scheduling scheme, typically being passed through a
`low pass filter.
`In one embodiment of a speed control mode of operation,
`the pole locations of the estimators 202, 302 are increased as
`speed increases, with the slowest pole locations occurring as
`the system is switched from open loop operation to closed
`loop operation.
`The gain values can be calculated for a range of speeds.
`This may be done on the fly by the gain scheduler 204, 304
`of FIG. 2 or 3 using a closed form set of equations.
`Alternatively, the gain values may be retrieved by the gain
`scheduler from one or more look-up tables or from fitted
`curves characterizing the gain-speed profile for a specific
`motor.
`
`FIG. 4 illustrates how gain values are varied with respect
`to the electrical speed in one exemplary embodiment so as
`to maintain observer poles at desired locations.
`FIGS. 5a and 5b illustrate how gain values approach
`excessive values as the electrical speed approaches zero. For
`this reason, gain values are preferably not calculated as
`described within a range of values around zero electrical
`speed. At low or zero speeds, predetermined gain values
`which are sufficiently high, but not excessive, are preferably
`used, thereby improving control system stability.
`FIG. 6 illustrates how gain values may be stored in and
`accessed from lookup tables. In the particular embodiment
`of FIG. 6,
`two columns of gain values are constructed
`through a multiplexer and then concatenated together to
`form a 4x2 gain matrix.
`FIG. 7 is a flow diagram 700 illustrating one preferred
`implementation of the gain schedulers 204, 304 of FIGS. 2
`and 3 in which the speed used by the gain scheduler, referred
`to as the scheduled speed, is set to the drive speed (i.e., a
`demanded rotor speed) at lower rotor speeds and to the
`estimated electrical speed at higher rotor speeds.
`In step 702, the controller transforms state variables into
`a rotating frame of reference. In step 704, the controller
`reads the estimated electrical speed and then reads the drive
`speed (i.e., the demanded speed) in step 706. In step 708, the
`controller compares the drive speed to a predetermined
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`US 7,342,379 B2
`
`5
`threshold speed. The predetermined speed threshold param-
`eter can be selected, as needed, for any given PM machine.
`If the drive speed is greater than the predetermined
`threshold speed,
`the scheduled speed used by the gain
`schedulers 204, 304 (FIGS. 2 and 3) is set equal to the
`estimated electrical speed in step 710. If the drive speed is
`less than the predetermined threshold speed, the scheduled
`speed used by the gain schedulers 204, 304 is set equal to the
`drive speed in step 712. Subsequent to controller selection of
`the appropriate scheduled speed, the selected schedule speed
`is used by gain schedulers 204, 304 to look up or calculate
`the estimator gains in step 714 to maintain the system poles
`at desired positions. The estimator uses the scheduled gain
`factors and the updated observer states in step 716 to
`calculate an updated estimated electrical angle in step 718
`and an updated estimated electrical speed in step 720. The
`updated electrical speed estimate is filtered in step 722 and
`the filtered speed estimate is integrated in step 724 to
`produce an updated electrical angle demand.
`According to another aspect of the present invention, a
`Qr-axis current can be selected that, in conjunction with a
`given value of dr-axis current, will produce a desired rotor
`torque. This aspect
`is particularly well suited to hybrid
`PM/SR motors, where the dr-axis current component con-
`tributes to the amount of torque produced, and especially
`hybrid PM/SR motors employing a dr-axis injection current.
`FIG. 8 is a flow diagram 800 illustrating a method of
`calculating a Qr-axis current based on a given dr-axis current
`injection to produce a desired rotor torque according to one
`exemplary embodiment. In this embodiment,
`the dr-axis
`current injection is calculated off-line in accordance with a
`dr-axis current injection method described in co-pending
`US. application Ser. No. 11/293,743 filed on even date
`herewith] noted above. These values are typically stored in
`a lookup table but may also be described as a mathematical
`function in alternative embodiments. The motor speed and
`the value of the dc-link are used to calculate the value of the
`
`dr-axis injection current to be applied at any given moment
`in time.
`
`In step 802, the controller reads the demanded electrical
`speed 802 and then reads the estimated electrical speed in
`step 804. In step 806, the controller calculates a speed error.
`The controller uses the calculated speed error from step 806
`to update the control action in step 808. After updating the
`control action,
`the controller reads the intended dr-axis
`injection current in step 810, calculates the Qr-axis current
`required to produce a demanded torque in step 812 and
`outputs the demanded Qr- and dr-axis currents in step 814 to
`a pair of current controllers, such as current controllers 206,
`208 of FIG. 2 or current controllers 306, 308 of FIG. 3.
`FIG. 9 is a block diagram of a speed loop controller 902,
`a torque to Ier Map block 904, and a Idr injection block
`906 according to another exemplary embodiment. As shown
`in FIG. 9,
`the selected Qr-axis current and the dr-axis
`injection current are multiplexed and provided to a pair of
`current controllers, preferably as a multiplexed demand
`signal, Ier demand 908. In this embodiment of the Idr
`injection block 906, the required Idr current is calculated
`from the speed error, assuming that Idr is for the moment
`nominally zero.
`FIG. 10 is a block diagram of the Torque and Idr to IQr
`map block of FIG. 9 according to another exemplary
`embodiment of the invention. In this embodiment, using the
`motor-specific constants noted, the Iqr_demand is calculated
`as:
`
`Iqridemand:(54.5 *Torque demand+0 .43 73 *Idr)/
`(22.54—Idr)
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`The decoupling of Ier components in the production of
`torque can be applied within either a sensorless control
`system or a sensor-controlled system. If a given motor does
`not show any discernible hybrid behavior, the control tech-
`nique can default to that classically used with a PM motor
`(i.e., Idr torque contribution is assumed to be zero) where the
`torque contribution comes from IQr.
`According to another aspect of the invention, the flux
`estimate produced by a flux estimator 202, 302, such as the
`estimators shown in FIGS. 2 and 3, can be compensated for
`saturation effects when the motor operates in the nonlinear
`saturation regions of stator magnetic flux. In this manner,
`errors in the flux estimate can be reduced, thus reducing
`errors in rotor position and/or rotor speed estimates pro-
`duced from the flux estimate. As a result, the stability of the
`control system is improved under stator saturation operating
`conditions. This improvement
`is particularly important
`when the structure of the drive control
`is based upon
`manipulating variables generated using transformations hav-
`ing values dependent on the machine electrical angle. This
`aspect of the invention is particular well suited for hybrid
`PM machines, PM machines having embedded rotor mag-
`nets, and PM machines employing highly magnetized mate-
`rial.
`
`The compensated flux estimate can be produced using
`nonlinear correction terms including, for example, dominant
`angle invariant terms associated with saturation, including
`cubic terms. Dominant angle-varying terms may also be
`used to produce the compensated flux estimate. Terms may
`also be present that include quadratic current expressions
`when they have a dominant effect on the flux estimate. In
`one embodiment of the invention directed to an air handler
`
`for a climate control system, the dominant terms are cubic.
`In one exemplary embodiment, a flux estimate is first
`produced using energization feedback 112
`from the
`machine. This flux estimate is then compensated for satu-
`ration effects, with the flux estimate becoming significant as
`the saturation effects themselves become significant
`FIG. 11 is a block diagram illustrating how saturation
`effects are compensated for in the measurement path of an
`Observer (e.g., embodied in a flux estimator) according to
`one exemplary embodiment of the invention. When the
`controller detects saturation operation of the stator,
`the
`compensated flux estimate is used by the estimator to
`estimate rotor speed and rotor position.
`According to another aspect of the present invention, a
`rotor position (i.e., angle) estimatorisuch as the estimators
`202, 302 shown in FIGS. 2 and 34can average samples of
`the energization feedback 112 from the machine and esti-
`mate the rotor position using the average sample values. In
`this manner, the magnitude of the potential error within each
`sampling interval
`is reduced in half, resulting in more
`accurate control of the machine when control of the machine
`
`is dependent on accurately estimating the rotor position.
`Although the magnitude of the potential error within each
`sampling interval increases as the sampling rate decreases,
`it should be understood that
`this aspect of the present
`invention can be advantageously used with any sampling
`rate to improve the accuracy of the estimated rotor position.
`The estimate calculation effectively compensates for time
`delays resulting from use of the angle estimate in the drive.
`Preferably, each successive pair of samples (including the
`second sample from the immediately preceding successive
`sample pair) is averaged to produce a series of average
`sample values which are used to estimate the rotor position.
`FIG. 12(a) illustrates how two samples are collected at the
`beginning and end of an exemplary sampling interval
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`US 7,342,379 B2
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`7
`according to the prior art, where each sample is treated as
`representing the actual rotor position/angle at the time such
`sample was obtained. FIG. 12(b)
`illustrates how two
`samples are collected and averaged to produce an estimated
`rotor position/angle. Collectively, FIGS. 12(a) and 12(b)
`illustrate that while the range of error (2e) remains the same,
`the absolute value of the potential error about the average
`angle estimate in FIG. 12(b) is reduced in half (+/—e) as
`compared to FIG. 12(a), where the angle error estimate
`could be as large as 2e.
`According to another aspect of the present invention, a
`trim-adjusted speed error can be calculated and provided,
`e.g.,
`to a speed controllerisuch as the speed controller
`shown in FIG. 3. An exemplary method includes producing
`a first rotor speed estimate, producing a second rotor speed
`estimate, and calculating a trim-adjusted speed error using
`the first rotor speed estimate and the second rotor speed
`estimate. Preferably, a trim value is produced by calculating
`a difference between the first rotor speed estimate and the
`second rotor speed estimate. Additionally, a raw speed error
`is preferably produced by calculating a difference between a
`demanded rotor speed and an estimated rotor speed (which
`may be the first rotor speed estimate or the second rotor
`speed estimate, and preferably the more reliable one of such
`estimates, which may depend, e.g., on the PWM rate of the
`motor drive). The trim-adjusted speed error is preferably
`calculated by adding the trim value to the raw speed error.
`The first rotor speed estimate can be produced using
`modeled motor parameters, and the second rotor speed
`estimate can be produced using zero crossings detected from
`energization feedback from the machine. In this manner, the
`trim value and thus the trim-adjusted speed error can
`account for potential variations between modeled motor
`parameters and actual parameters of a production motor.
`FIG. 13 is a block diagram of an exemplary trim mecha-
`nism for producing a trim value that can be provided, e.g.,
`to an estimator such as the estimator shown in FIG. 3. In this
`
`embodiment, the trim error 1302 is filtered using a first order
`low pass filter 1304. The filtered trim error signal 1306 is
`then added directly to the error signal driving the speed loop
`controller. FIG. 9, discussed above, illustrates an exemplary
`speed controller that includes an input 910 for such a trim
`value. The trim mechanism can be used to improve the
`performance of an estimator-based sensorless control sys-
`tem.
`What is claimed is:
`
`1. A method of controlling a permanent magnet rotating
`machine, the machine including a stator and a rotor situated
`to rotate relative to the stator, the stator having a plurality of
`energizable phase windings situated therein, and an estima-
`tor having at
`least one gain value and employing an
`observer, the method comprising:
`varying the gain of the estimator as a function of either a
`demanded rotor speed or an estimated rotor speed to
`thereby position poles of the observer at desired loca-
`tions.
`
`2. The method of claim 1 wherein varying includes
`varying the estimator gain while operating in a closed loop
`control mode.
`
`3. The method of claim 1 wherein varying includes
`varying the estimator gain with respect to the demanded
`rotor speed when the actual rotor speed is outside a pre-
`defined range, and varying the estimator gain with respect to
`the estimated electrical speed when the actual rotor speed is
`within the predefined range.
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`4. The method