西班牙专利ES2690409A1 DEVICE AND PROCEDURE FOR DETERMINING THE TORQUE, SPEED AND ENERGY LOSSES OF THREE-PHASE ASYNCHRONOUS

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专利摘要:
Device and procedure for determining the torque, speed and energy losses of three-phase asynchronous electric motors. The invention describes a novel method and device for the determination of the torque, speed and energy losses of three-phase asynchronous electric motors from the direct measurement of the stator currents with the motor in operation. (Machine-translation by Google Translate, not legally binding)
公开号:ES2690409A1
申请号:ES201830377
申请日:2018-04-18
公开日:2018-11-20
发明作者:Vicente LEÓN MARTÍNEZ；Joaquín MONTAÑANA ROMEU
申请人:Universidad Politecnica de Valencia；
IPC主号:

专利说明:

DEVICE AND DETERMINATION PROCEDURE OF THE PAR, THESPEED AND ENERGY LOSS OF ELECTRIC MOTORS
Three-phase asynchronous
Field of the Invention
The present invention generally relates tofield of three-phase asynchronous electric motors, and morespecifically to the determination of characteristics ofoperation of said engines (torque, speed and lossesenergy) from simply a direct measure ofStator currents with the engine running.
Background of the invention
As is known in the art, the operation ofAsynchronous (induction) motors are defined by thetorque and speed values on its axis. In addition, theengine energy losses can report onCauses of possible engine failures.
Today, many are available in the marketmechanical torque and speed measuring instruments,but they are generally expensive devices and, in someSometimes, they cannot connect to the motor due to severalreasons (for example, because the instruments disturb theproduction process, there are space limitations, theengine is not ready to incorporate the instruments,...) Energy losses could be estimated by measuring theengine temperature, but this procedure does not distinguishAs for the causes of energy loss.
Mechanical torque and Joule losses in enginesAsynchronous depend on rotor currents. So,in cases where, for example, the cost cannot be assumedof torque and velocity measuring instruments or whenthese measuring instruments cannot be installed in the

engine, an alternative procedure to determine torqueengine, speed and losses by Joule in enginesthree-phase asynchronous could consist of measuringrotor currents
Stator currents can be easily measured inelectric motors, but the rotor currents aredifficult to measure directly since the windings of therotor are not available in 90% of enginesinduction (rotor in short circuit of motors) and, thereforetherefore, the measurement of rotor currents requires techniquesInvasive in engines.
In the publication “Induction Motors Loss of Life due toVoltage Imbalance and Harmonics: A Preliminary Study ”,presented by J. Policarpo and A.E. Emmanuel at the 2000 NinthInternational Conference on Harmonics and Quality of Power,the authors break down energy losses frommodels of other authors (P.G. Cummings or E.F. Fuchs, betweenothers), without using the indirect measurement of the current of therotor, or separate the energy losses of the core from theJoule.
The document “Torque and speed estimation for linestart IM using dot-cross Products of current and voltagevectors ”IPEMC 2009, by Takahashi A; Oguro R, refersto a procedure for estimating the torque and speed ofan electromagnetic machine using only the currentand the tension, not being necessary some parameters in theprocess. Parameter values are achieved.by measuring or identifying rotor resistanceand mutual inductance.
The document “Improved torque and speed estimation insensorless induction motor drive ”, by Kalilah S.A., disclosesan algorithm that consists in improving the torque estimation andspeed without sensor in drive with motor

induction. It is based on a precise mathematical model thatdepends on the actual engine parameters, which vary withstator frequency, rotor slip andenvironmental condition Polynomial equations ofhigh order to get torque and speed through thedigital measurement of the current and frequency of the statorwithout any sensor
The document “Induction machines performance evaluator'torque speed estimation and rotor fault diagnostic ”, byHaji M; Ahmed S; Toliyat H A, 2002, describes a techniquefor machine performance evaluation ofinduction. In the proposed procedure, the curve is estimatedspeed-torque and motor condition is classified. The only oneinformation required for this algorithm is the number ofpoles, rotor grooves and stator currents.
CN-201510613382-A describes a processof measuring an optimum speed of rotation and a curve oftorque tracking of a shaft wind generator setvertical. In this document, the possibility ofdetermination of a speed estimation curve ofturn and torque as an accessory means for the average speedOptimal rotation and plotting of the torque curve.
Therefore, the need still exists in the artof a procedure and device for indirect obtainingof the values of torque, speed and energy losses(Joule + core) in three-phase asynchronous motors,using the values of the voltages and currents of thestator
Summary of the invention
To solve the problems of the techniquesabove, the present invention discloses, according to afirst aspect, a torque determination procedure,

the speed and energy losses of three-phase asynchronous electric motors, comprising the steps of: i) acquiring instantaneous values of voltage (,,) and intensity (,,) in the stator

of the phases (A, B, C) at the point of connection of the motor with the mains, obtaining its effective values, (,,) and (,,), as well as the complex values of the components at the fundamental frequency, (,, �) and (̅, ̅, ̅);

ii) determine, from the components at the fundamental frequency, the complex components positive, negative and zero of the voltages (,,,) and the positive and negative sequence currents (̅, ̅) of the stator;

iii) determine the effective values of the components of the positive stator voltage and imbalance (,,) and of the stator currents (,) as:

= + = � [1] and, from the effective values at the fundamental frequency (,, �) and (,, �) and the
effective values of the stator voltages and currents (,,) and (,,) obtained in step i), determine the harmonic distortion components of the stator voltage () and the stator current (), where z = A, B, C,
�
= ∑ − ∑� = ∑ − ∑� [2] iv) characterize the motor, obtaining its nominal complex current from the empty stator, of positive sequence, at the fundamental frequency

(), the active () and reactive () vacuum power;
v) obtain the resistance of losses in the core () and the magnetizing reactance () of each phase of the motor, from the nominal simple voltage of the stator () and the nominal () and reactive () nominal vacuum powers, like: �
≈6� ≈3� [5]
vi) insert the nominal values of the pair (�),
speed (), sync speed (),
fundamental frequency () and stator current ();
vii) obtain the effective value of the nominal rotor current reduced to the stator (′) as the vector difference module
′ = −� [7] the complex current of the nominal stator being
= ∠−.
viii) determine the value of the nominal rotor resistance reduced to the stator (′) from the nominal characteristics:
′ = � (-) [8]
�
ix) calculate the complex vacuum current at the fundamental frequency of each phase (z = A, B, C) of the stator (̅) as the ratio between the complex voltage applied to each phase of the stator to the fundamental frequency ( �) and the complex vacuum impedance (̅), that is,
̅≈=∙ + � [9]

x) apply the Fortescue theorem to obtain the positive (̅) and imbalance (̅ = ̅�) sequence components of the vacuum currents, at the fundamental frequency;
xi) calculate the effective value of the distortion current of each phase of the stator running in a vacuum () by the ratio between the effective value of the voltage distortion component applied to each phase (z = A, B, C) of the stator () and the resistance of losses in iron, ≈ [10]
�
since the distortion current flowing through the magnetizing reactance (�) can be considered negligible;
xii) determine the effective value of the positive sequence component and fundamental frequency of the rotor current reduced to the stator (′),
′ = −� [11]
xiii) determine the effective value of the imbalance current of the rotor reduced to the stator as: ′ = −� [12]
xiv) obtain the effective value of the currents ofdistortion of each rotor phase reduced to
′
stator () as the quadratic difference ofcurrents of each phase of the stator in charge ()and empty (),′ �
= −� [13]
xv) from the components of the rotor current reduced to the stator (′, ′, ′) and the
�
nominal rotor resistance reduced to the stator (′), obtain energy losses by Joule

depending on the current components of therotor:
to. Fundamental and positive
� 3′′�
b. Fundamental and unbalanced [14]
� 3′′�
C. Harmonic distortion
= ′ � � ′ � ,, �
xvi) from the components of the stator voltage (,,) and the resistance of losses

5 in the core (Re), get the energy lossesin the core depending on the components of thestator voltage:
to. Fundamental and positive
= 3 1�
b. Fundamental and unbalanced [15]
= 3 1�
C. Harmonic distortion
= 1� � ,, �
xvii) on the basis of the nominal characteristics of the motor previously introduced, determine the mechanical torque () and the speed () developed on the motor shaft when another sinusoidal voltage of the same fundamental frequency () and sequence is applied to the stator positive, but of effective value () different from the nominal value
15 (), like:
� ()
= ′ ′ � = −− ′ ′ � [17]
where ′ � is the effective value of the reduced nominal current of the rotor, and ′ � is the reduced current of the rotor for the new voltage of the 20 stator (), which is obtained as a function of the current measured in the stator in these

conditions (̅) and nominal vacuum current ̅
(), as:

′ = −� [18]
As can be seen, the proceduredescribed above according to the present invention avoids therequirement to use expensive torque measurement instruments andof speed, since only one voltmeter is needed,an ammeter and a wattmeter connected to the stator.In addition, the procedure allows decomposing lossesenergy efficiency by Joule effect on: fundamentals(balanced and unbalanced) and not fundamental, and inThe components of core losses.
According to additional embodiments, as will be seencontinued in this document, the procedureaccording to the present invention it can also be extended toAsynchronous motor speed control. If the regulatorspeed is a frequency converter connected to themotor stator side, the procedure requires theadditional measure of the fundamental frequency ofvoltages applied to the motor. If the speed regulatorIt is formed by external rotary resistors, it mustKnow the value of these resistances.
According to another aspect of the present invention, it is given toknow a torque determination device, speedand the energy losses of asynchronous electric motorsthree-phase, which comprises
-a means of measurement and data acquisition;
-a processor;
-a means of calculation;
-a means of data entry; Y
-a visualization means.
The means of calculation are adapted to lead to

carry out the steps of the procedure according to the first aspect ofThe present invention.
Brief description of the drawings
The present invention will be better understood with reference.to the following drawings illustrating embodimentspreferred of the present invention, provided by way ofas an example, and that should not be construed as limitingThe invention in any way:
Figure 1 is a diagram showing the sequenceOperational procedure according to the preferred embodimentof the present invention.
Figure 2 is a diagram representing apreferred embodiment of the device for measuring thetorque, speed and energy losses according to thepresent invention
Figures 3 and 4 are diagrams representingalternative embodiments of the torque measuring device,speed and energy losses for measurement in differentengines, in which the means of measurement and acquisition ofdata and processor are in remote locationswith each other and are connected throughmedia, whether through mediaWireless or cable.
Figure 5 is a diagram representing the modulesprogramming for the torque measuring devicemechanical, speed and energy losses according to thepreferred embodiment of the present invention.
Figure 6 shows a representation of the means ofdisplay of the measuring device according to apreferred embodiment of the present invention.
Detailed description of the preferred embodiments

As mentioned earlier, a first aspect
of the present invention relates to a method of
Determination of torque, speed and losses
energy of three-phase asynchronous electric motors.
According to a preferred embodiment of the present invention, the
The procedure includes the steps of: i) acquiring the instantaneous values of voltage (,,) and intensity (,,) in the stator of the phases (A, B, C) at the point of connection of the motor with the power grid, obtaining their effective values, (,,) and (,,), as well as the complex values of the components at the fundamental frequency, (,,) Y)

of said phase voltages and currents;
ii) determine, from the components at the fundamental frequency, the complex components positive, negative and zero of the voltages (,,,) and the positive and negative sequence currents (̅, ̅) of the stator;

iii) determine the effective values of the components of the positive stator voltage and imbalance (,,) and of the stator currents (,) as:

= + = � [1] and, from the effective values at the fundamental frequency (,,) and (,,) and the
� �
effective values of the stator voltages and currents (,,) and (,,) obtained in step i), determine the harmonic distortion components of the stator voltage () and the stator current (), where z = A, B, C,

�
= ∑ − ∑� = ∑ − ∑� [2]
iv) characterize the motor, obtaining its nominal complex current of the stator in a vacuum, of positive sequence, at the fundamental frequency (), the active () and reactive () power of
empty, by one of the followingalternative procedures:
to. performing a vacuum test of the electric motor, letting its axis rotate freely (disconnecting the load), feeding the motor by a three-phase voltage source, of effective value in each phase () equal to the nominal simple voltage of the motor, and measuring Under these conditions the positive sequence component and fundamental frequency of the stator currents in vacuum (), as described in stages i) and ii), and calculating the nominal active () and reactive () vacuum powers as:
b. using the following catalog or motor nameplate data:, nominal mechanical power, the nominal simple voltage of the stator, nominal efficiency and, the angle of the nominal power factor, to obtain approximately the values of active () and reactive () vacuum power
∗ ∗
= 3 ∙ � = 3 ∙ � [6]
as: � ≈4 ÷ 10% � � ≈� � [3]
Y hevaluecomplexfromthecomponentfrom
sequence positive,tothefrequency
12

fundamental, of vacuum currents, such as:
≈�
̅∠⁄� [4]
�
v) obtain the resistance of losses in the core () and the magnetizing reactance () of each phase
5 of the motor, from the nominal simple voltage of the stator () and of the nominal active () and reactive () vacuum powers, obtained in stage iv), such as:
≈6� ≈3� [5]
� � �
10 vi) insert the nominal values of the torque (�), speed (), synchronism speed (), fundamental frequency () and stator current (); vii) obtain the effective value of the nominal current
15 of the rotor reduced to the stator (′) as the module of the vector difference ′ = - � [7] being the complex current of the nominal stator = ∠−.
20 viii) determine the value of the nominal rotor resistance reduced to the stator (′) from the nominal characteristics:
′ = � () [8]
� -
ix) calculate the complex vacuum current at the
25 fundamental frequency of each phase (z = A, B, C) of the stator (̅) as the ratio between the complex voltage applied to each phase of the stator to the fundamental frequency ( �) and the complex vacuum impedance (̅), that is,

̅≈=∙ + � [9]
x) apply the Fortescue theorem to obtain the positive (̅) and imbalance (̅ = ̅�) sequence components of the vacuum currents, at the fundamental frequency;
xi) calculate the effective value of the distortion current of each phase of the stator running in a vacuum () by the ratio between the effective value of the voltage distortion component applied to each phase (z = A, B, C) of the stator () and the resistance of losses in iron, ≈ [10]
�
since the distortion current flowing through the magnetizing reactance (�) can be considered negligible;
xii) determine the effective value of the positive sequence component and fundamental frequency of the rotor current reduced to the stator (′),
′ = −� [11]
xiii) determine the effective value of the current ofimbalance of the rotor reduced to the stator as:
′ = −� [12]
xiv) obtain the effective value of the currents ofdistortion of each rotor phase reduced to′
stator () as the quadratic difference ofcurrents of each phase of the stator in charge ()and empty (),′ = � −� [13]

xv) from the components of the rotor current reduced to the stator (′, ′, ′) and the
�

Nominal rotor resistance reduced to the stator (′), obtain the energy losses per Joule as a function of the rotor current components:
to. Fundamental and positive
� 3′′�
b. Fundamental and unbalanced [14]
� 3′′�
C. Harmonic distortion
= ′ � � ′ � ,, �
5 xvi) from the components of the stator voltage (,,) and the resistance of losses

in the core (Re), get the energy lossesin the core depending on the components of thestator voltage:
to. Fundamental and positive
= 3 1�
b. Fundamental and unbalanced [15]
= 3 1�
C. Harmonic distortion
= 1� � ,, �
10 xvii) from the nominal motor characteristics previously introduced, determine the mechanical torque () and speed () developed on the motor shaft when another sinusoidal voltage of the same frequency is applied to the stator
15 fundamental () and positive sequence, but of
effective value () different from nominal value
(), as:
= � ′ � = - (-) ′ � [17]
′ � ′ �
where ′ � is the effective value of the current
20 nominal reduced rotor, e ′ � is the reduced rotor current for the new voltage of the

stator (), which is obtained based on the
current measured in the stator in these
conditions (̅) and nominal vacuum current
̅
(), as:

I ′ = I − I� [18]
According to a first alternative, when the procedure is applied to a motor regulated by an electronic frequency converter, the procedure further comprises, before stage xvii), the step of recording the fundamental frequency () of the stator voltages and currents. As the person skilled in the art will understand, in the general case in which the motor is not regulated by an electronic frequency converter, the fundamental frequency in the stator is always equal to the frequency of the mains (=).
According to a second alternative, when the procedure is applied to a motor regulated by external resistors () connected to the rotor, the method further comprises, before stage xvii), the step of obtaining the value of the rotor resistance reduced to the stator ( '), through
′ ′ ′
= +. � [16]
In addition, in the process according to any of the alternatives described above, step xvii) comprises determining the mechanical torque () and speed () developed on the motor shaft by:
′ � ′ ′
= � = - (-) [19]
� ′ � ′ � ′ �
It will be described in more detail below,referring to figure 1, a preferred embodimentof the procedure described above. The procedureaccording to the preferred embodiment shown in figure 1It includes the following operations:

-Digital processing (1) of the sampled signalsobtained by the physical device (see figure 2) ofmeasurement and acquisition of electrical signals from the device,obtaining (in 2) the matrices of effective values and phasesinitial voltage and intensity at fundamental frequencyfor each phase, in total six matrices for each phase ofvoltage and intensity, as well as (in 3) effective valuesof the stator voltages and currents.
-With these matrices you get (in 4) the valueseffective and initial phases of sequence componentspositive, negative and zero of the voltages and currents ofStator at the fundamental frequency.
-From effective value matrices andinitial phases of tension and intensity of the componentssymmetric (in 4) and of the effective values of tensionsand stator intensity (in 3), the values are obtainedEffective components of voltage and intensity (in 5),according to the expressions [1] and [2], shown above.
-From a vacuum test (in 6) theeffective values and their initial phases of stress epositive stator intensity at fundamental frequency,obtaining the active and reactive power of vacuum, according to theexpression [6] shown above.
-From the input data of the catalog of themotor (in 7), the estimated values of theactive and reactive vacuum power, according to the expression [3],shown above.
-From the powers obtained (in 6 or 7)determine the equivalent empty circuit elements(in 8), according to the expression [3], shown above.
-From the equivalent circuit elementsin vacuum (at 8) and the stator nominal voltage, positive,at fundamental frequency, the effective value and phase is obtained

initial of the nominal vacuum current (in 9), according to theexpression [4], shown above.
-From the effective value and initial phase of thenominal intensity of the positive stator at frequencyfundamental in vacuum (in 9) and the effective value and initial phaseof the nominal intensity of the stator (in 7), thenominal rotor intensity reduced to the stator (by 10),according to the expression [7], shown above.
-From the motor input data (in 7),the nominal rotor resistance reduced bystator (at 11), according to the expression [8], shownpreviously.
-From the equivalent circuit elementsin vacuum (at 8) and the stator voltage, positive, tofundamental frequency, and distortion are obtained (in 9)the effective values and the initial phases of the currentsof vacuum of each phase and its components at the frequencyfundamental and distortion, according to the expressions [9] and[10], shown above.
-From the components of the intensity of thestator (in 5) and the components of the currents ofvacuum (in 9), the current components are obtainedfrom the rotor reduced to the stator (in 12), according to the expressions[11], [12], [13] and [18], shown above.
-From the nominal rotor resistancereduced to the stator (at 11) and the current componentsfrom the rotor reduced to the stator (at 12), theenergy losses by Joule (at 13), according to the expressions[14], shown above.
-From the equivalent core resistance(in 8) and the components of the stator voltage (in 5),the energy losses in the core are obtained (in 14),according to the expressions [15], shown above.

-From the nominal characteristics of themotor (at 7), the nominal rotor intensity reduced tostator (at 10), the rotor intensity reduced to the stator(in 12) and the stator voltage (in 5), the torque is obtainedmechanical and speed (in 17), according to the expression [17],shown above.
-From the value of the connected resistorsto the rotor and the effective values of the nominal intensitiesfrom the reduced rotor to the stator and from the stator (at 15),gets the rotor resistance value reduced bystator, according to the expression [16], shown above.
-From the voltage and frequency measurementfundamental of the electronic converter (in 16) and / or the valueof the rotor resistance reduced to the stator, are obtainedthe mechanical torque and the speed on the shaft (at 17), according to theexpression [19], shown above.
-The graphical and numerical information of the pairmechanical, speed and energy losses, as well ascertain values of the physical quantities used duringthe procedure, are displayed (in 18) on a devicedisplay.
A preferred embodiment ofa device for the implementation of the procedureof determination described above, comprisingphysical means of measurement and data acquisition (signalselectrical) (A), a processor (B), as well as a means ofcalculation (C), a means of data entry and somedisplay means (D).
The physical means of measurement and data acquisition (A)they include signal conditioners and a cardData acquisition. Signal conditioners adaptthe instantaneous values of the voltages and currents of thesecondary of voltage and intensity measurement sensors

(E), so that the tensions in their outputs can beapplicable to the analog inputs of the cardacquisition or equivalent device, which convertsanalog voltage and current signals in a series ofdiscrete samples that are used as input in themeasurement program The processor (B) has a platebase on which the acquisition card is placed so thatdiscrete signals can be exchangedof voltage and intensity with the measurement program (C), atwhich you can enter the technical specificationsof the three-phase asynchronous motor by means ofdata entry In the display media (D)visualize all the information about the waveforms and thevalue of all electrical quantities related to theMeasurement of mechanical torque, speed and lossesenergy namely: tensions, intensities, losses due toJoule and core and its components in the asynchronous motorthree phase
According to a preferred embodiment, the means ofdata entry and display media canbe implemented jointly through a screentactile.
As shown in Figure 2, the measuring meansand data acquisition (A) and processor (B) meetwithin the same housing and are connected by meansphysical (wired).
According to other embodiments of the device according to thepresent invention, the means of measurement and acquisition ofdata (A) and processor (B) are in locationsremote with each other and are connected tothrough the media, either by means ofWireless or cable communication.
For example, as shown in Figure 3, the

measurement and data acquisition means (A) and the processor
(B) are connected through mediawireless (WiFi or IoT subnet). To do this, the deviceIt also includes a WiFi communication card to operateof interface between the means of measurement and data acquisition
(TO) and the processor (B).
According to another alternative shown in Figure 4, themeasurement and data acquisition means (A) and the processor
(B) are connected through media bycable (Ethernet subnet). To do this, the deviceIt also includes a network card to act as an interfacebetween the means of measurement and data acquisition (A) and theprocessor (B).
Referring now to Figure 5, they will be described.the various modules that make up the means of calculation(measurement program) (C) according to a preferred embodiment ofThe present invention:
- Digital signal processing module (19), whichacquires samples of voltage and intensity, and stores them inA vector for each of them.
-Analysis module (20), in which theeffective values and the initial phase of tensions andStator fundamental frequency currents, as well asthe effective values of the voltages and currents ofstator, from the samples acquired in the moduledigital signal processing (19).
-Symetric module (21), which obtains the matricesof the positive, negative and zero sequence components,in effective value and in phase, of the tensions and currents of thestator at the fundamental frequency, from the matricesobtained in the previous module.
-Stator component module (22), which obtainsthe matrices of the positive sequence components, in

effective and phased value of the voltages and currents of theStator at the fundamental frequency and effective valuesof the imbalance and harmonic distortion components ofthe tensions and currents of the stator, according to the expressions
[1] and [2] shown above, from the matricesobtained in the previous module.
-Vacuum features module (25), which obtains:a) the values of the equivalent circuit elements of theempty motor, according to the expression [5] aboveshown, from the motor input data (24)according to the expression [3] shown above, or fromof the vacuum test performed (23) according to the expression [6]above shown, and, b) the stator current inempty, in effective value and initial phase, from the dataof the motor (24), according to the expression [4] shown above
or from the vacuum test as a direct measure from theprevious module (22).
- Nominal rotor characteristics module (26),which obtains the nominal rotor current reduced bystator, according to the expression [7] shown above, and thenominal rotor resistance reduced to the stator, according to theexpression [8] shown above.
- Rotor current component module (27),which gets the rotor current componentsreduced to the stator, according to the expressions [11], [12] and [13]previously shown, based on the data obtained inthe empty feature modules (25) and theStator components (22).
-Joule loss module (28), in whichobtains energy losses from Joule and its components,based on the data obtained in the modulesnominal characteristics of the rotor (26) and the componentrotor current (27), according to the expressions

[14] previously shown.
-Module of losses in the core (29), in whichget the energy losses in the engine core andits components, based on the data obtained in the modulesof characteristics of the stator in vacuum (25) and that ofStator current components (22), in accordance withthe expressions [15] shown above.
-Control module (30), if any system is availableof regulation, selecting between: a) control byrotary resistors, in which the value ofthe external resistance connected to the rotor and from theeffective values of rotor and stator currentsnominal, the rotor resistance value is obtainedreduced to the stator, according to the expression [16] aboveshown, b) electronic converter, in which it is registeredthe fundamental frequency of the stator from the moduleanalysis (20).
- Torque and speed module (31), in which it is obtainedmechanical torque and engine speed, according to the expression
[17] shown above, if there is only adjustment in theStator voltage value, and expression [18]previously shown, if there is any type of regulationby rotary resistors or electronic converter,chosen in the previous module.
-Display module (32), responsible for displaying ina screen the graphical and numerical information of the pairmechanical, speed and energy losses, as well ascertain values of the physical quantities used duringthe procedure, as shown by way of example inFigure 6
In accordance with the foregoing, the present invention resolvesseveral relevant aspects that differentiate and conferclear advantages over previous techniques:

- Indirect measurement of rotor current, fromof the direct measurement of the stator currents.- Indirect measurement of energy losses byseparate, core and Joule, with the engine running.
5 -Measurement of the components of energy lossesdue to currents (Joule) and voltages (core):fundamentally balanced, imbalances and harmonics.
-Simple implementation.
The invention has been described with reference to
10 preferred embodiments thereof. However, the person skilled in the art will understand that various modifications and variations can be applied to said embodiments without thereby departing from the scope of protection provided by the appended claims.

权利要求:
Claims (9)
[1]
1. Procedure for determining torque, speed andenergy losses of electric motorsthree-phase asynchronous, comprising the stages of:i) acquire instantaneous voltage values
(,,) and intensity (,,) in the stator
of the phases (A, B, C) at the point of connection of the motor with the mains, obtaining its effective values, (,,) and (,,), as well as the complex values of the components at the fundamental frequency, (,, �) and (̅, ̅, ̅);
ii) determine, from the components at the fundamental frequency, the complex components positive, negative and zero of the voltages (,,,) and the positive and negative sequence currents (̅, ̅) of the stator;
iii) determine the effective values of the components of the positive stator voltage and imbalance (,,) and of the stator currents (,) as:
= + = � [1] and, from the effective values at the fundamental frequency (,,) and (,, �) and the
effective values of the stator voltages and currents (,,) and (,,) obtained in step i), determine the harmonic distortion components of the stator voltage () and the stator current (), where z = A, B, C,
�
= ∑ − ∑� = ∑ − ∑� [2]

iv) characterize the motor, obtaining its nominal complex current of the stator in a vacuum, of positive sequence, at the fundamental frequency (), the active () and reactive () vacuum power;
v) obtain the resistance of losses in the core () and the magnetizing reactance () of each phase of the motor, from the nominal simple voltage of the stator () and the nominal () and reactive () nominal vacuum powers, how:
≈6� 3� [5]
� � ≈�
vi) insert the nominal values of the torque (�), speed (), synchronism speed (), fundamental frequency () and stator current ();
vii) obtain the effective value of the nominal current of the rotor reduced to the stator (′) as the module of the vector difference ′ = - � [7] being the complex current of the nominal stator = ∠−.
viii) determine the value of the nominal rotor resistance reduced to the stator (′) from the nominal characteristics:
′ = � () [8]
� -
ix) calculate the complex vacuum current at the fundamental frequency of each phase (z = A, B, C) of the stator (̅) as the ratio between the complex voltage applied to each phase of the stator to the

fundamental frequency ( �) and impedance
vacuum complex (̅), that is,
̅≈=∙ + � [9]
x) apply the Fortescue theorem to obtain the
components of positive sequences (̅) and of
imbalance (̅ = ̅�) of the vacuum currents, at the fundamental frequency;
xi) calculate the effective value of the distortion current of each phase of the stator running in a vacuum () by the ratio between the effective value of the voltage distortion component applied to each phase (z = A, B, C) of the stator () and the resistance of losses in iron, ≈ [10]
�
xii) determine the effective value of the positive sequence component and fundamental frequency of the rotor current reduced to the stator (′),
′ = −� [11]
xiii) determine the effective value of the current ofimbalance of the rotor reduced to the stator as:
′ = −� [12]
xiv) obtain the effective value of the currents ofdistortion of each rotor phase reduced to
′
stator () as the quadratic difference of
currents of each phase of the stator in charge ()
and empty (),
′
= −� [13]
xv) from the components of the rotor current reduced to the stator (′, ′, ′) and the
�
nominal rotor resistance reduced to stator

(′), Obtain the energy losses per Joule based on the rotor current components:
to. Fundamental and positive
� 3′′�
b. Fundamental and unbalanced [14]
� 3′′�
C. Harmonic distortion
= ′ � � ′ � ,, �
xvi) from the components of the voltage of the 5 stator (,,) and the resistance of losses
in the core (Re), get the energy lossesin the core depending on the components of thestator voltage:
to. Fundamental and positive
= 3 1�
b. Fundamental and unbalanced [15]
= 3 1�
C. Harmonic distortion
= 1� � ,, �
xvii) from the nominal characteristics of the
10 previously introduced motor, determine the mechanical torque () and speed () developed on the motor shaft when another sine voltage is applied to the stator, of the same fundamental frequency () and of positive sequence, but of
15 effective value () different from nominal value
(), as:
′ � ′
= � = - (-) [17]
′ � ′ �
where ′ � is the effective value of the reduced nominal current of the rotor, and ′ � is the reduced current 20 of the rotor for the new stator voltage (), which is obtained as a function of the

current measured in the stator in these
conditions (̅) and nominal vacuum current ̅
(), as:
′ = −� [18] [2]
2. Method according to claim 1, characterized in that step iv) of characterizing the motor is carried out by a vacuum test of the electric motor, allowing its axis to rotate freely (disconnecting the load), the motor being fed by a voltage source three-phase, of effective value in each phase () equal to the nominal simple voltage of the motor, and in these conditions measuring the positive sequence component and fundamental frequency of the stator currents in
vacuum (), as described in steps i) and
ii), and calculating the active () and reactive powers
() vacuum ratings such as:
∗∗ = 3 ∙ � = 3 ∙ � [6].
[3]
3. Method according to claim 1, characterized in that step iv) of characterizing the motor is carried out using the following catalog or motor nameplate data:, nominal mechanical power, the nominal simple voltage of the stator,, nominal efficiency and, the angle of the nominal power factor, to obtain approximately
values of active () and reactive () vacuum power, such as:
≈4 ÷ 10% � ≈� [3]
and the complex value of the sequence component
positive, at the fundamental frequency, of the
vacuum currents, such as:

[4]
Four.
[5]
5.
[6]
6.
[7]
7.
≈�
̅� ∠⁄� [4]. Method according to any of the preceding claims, in which the motor is regulated by an electronic frequency converter, characterized in that it also comprises, before stage xvii), the step of recording the fundamental frequency () of the
Stator voltages and currents. Method according to any of the preceding claims, wherein the rotor is regulated by external resistors (�) connected to the rotor, characterized in that it also comprises, before stage xvii), the step of obtaining the reduced rotor resistance value to the stator (′ �), by
′ ′ ′
= +. � [16].
Method according to any of claims 4 and 5, characterized in that step xvii) comprises determining the mechanical torque () and the speed ()
developed on the motor shaft by:
� ′ � ′ ′
== � - (-) [19].
′ � ′ ′ � Device for determining the torque, speed and energy losses of three-phase asynchronous electric motors, comprising -a means of measurement and data acquisition (A); -a processor (B); -a means of calculation (C); -a means of data entry; and -a visualization means (D); the calculation means (C) being adapted to carry out the process steps according to a

any of claims 1 to 6.
[8]
8. Device according to claim 7, characterizedwhy the means of measurement and data acquisition (A)and the processor (B) are connected through means
5 physicists
[9]
9. Device according to claim 7, characterizedwhy the means of measurement and data acquisition (A)and the processor (B) are in remote locationswith each other and are connected through
10 media.

32

FIG. 2
33

3. 4

35

36

37

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同族专利:

公开号 | 公开日

ES2690409B2|2019-05-31|

WO2019202188A1|2019-10-24|

引用文献:

公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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优先权:

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ES201830377A|ES2690409B2|2018-04-18|2018-04-18|DEVICE AND PROCEDURE FOR DETERMINING THE TORQUE, THE SPEED AND THE ENERGETIC LOSS OF THREE-PHASE ASYNCHRONOUS ELECTRIC MOTORS|ES201830377A| ES2690409B2|2018-04-18|2018-04-18|DEVICE AND PROCEDURE FOR DETERMINING THE TORQUE, THE SPEED AND THE ENERGETIC LOSS OF THREE-PHASE ASYNCHRONOUS ELECTRIC MOTORS|

PCT/ES2019/070248| WO2019202188A1|2018-04-18|2019-04-10|Device and method for determining torque, speed and energy losses of three-phase asynchronous electric motors|

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