Method for configuring a motor drive and device for implementing the method

Abstract

There is provided a method for configuring a motor driver for driving an induction motor, the method comprising: the motor comprising a rotor and a magnetic core comprising a magnetic induction component; performing N measurements of the voltage at the motor terminals of the motor while the motor is stationary during demagnetization of the magnetic core of the motor; determining an estimate of a magnetic induction component of the electric machine operating in a linear manner based on the N voltage measurements; determining an estimate of a time constant of the motor rotor operating in a linear manner based on one of the N voltage measurements; an estimate of a rotor resistance of the electric machine is determined based on the estimate of the magnetic induction component of the electric machine and the rotor time constant.

Description

Technical Field

[0001] The present disclosure relates to the field of induction motors and uses thereof, and more particularly to an apparatus configured to drive an induction motor. Background Art

[0002] Induction motor drives are typically designed to operate with any induction motor based on drive parameters that are determined during a measurement phase, sometimes referred to as a “motor tuning” phase.

[0003] Therefore, the motor drive is not typically pre-configured so that it can be configured to operate with any motor drive to which it is coupled. Therefore, the motor tuning phase typically includes taking measurements of the motor drive to determine estimates of tuning parameters or characteristics of the induction motor to which the motor drive is coupled, and using the determined tuning parameters and characteristics to configure the motor drive for driving the induction motor.

[0004] For example, tuning parameters or characteristics such as stator resistance, leakage inductance and magnetization curve of an induction motor may be determined in order to configure the motor drive and achieve efficient regulation of the induction motor. Accurate determination of these parameters is desirable in order to optimize motor behavior for greater efficiency.

[0005] Adjustment of these parameters is therefore a critical process during commissioning of a motor drive that will be configured to drive a given induction motor.

[0006] There are two different types of tuning procedures for motor drives of induction motors: rotating tuning and stationary tuning. Rotating tuning is performed with the motor spinning, while stationary tuning is performed with the motor held stationary. Rotating tuning is known to produce a more accurate estimate of the tuning parameters because more accurate measurements can be obtained on a spinning motor than when the motor is held stationary.

[0007] However, starting the induction motor in order to measure tuning parameters for configuring a motor drive for driving the motor may constitute a constraint. Therefore, it is known that static tuning is more convenient to use, especially in cases where the mechanical coupling constitutes a limitation (e.g., where the mechanical coupling is difficult to undo or redo).

[0008] The stationary tuning procedure for induction motors usually uses direct current (DC) injection to magnetize the motor's internal core and analyze the core's response. Analyzing the response involves measuring the motor while it is stationary. Therefore, the quality of the estimated tuning parameters depends on the accuracy of the measurements. However, measurement equipment that can provide accurate measurements even at very low values ​​of the measured quantity (such as voltage) (which is usually the case for stationary motors) is not always available, which results in low tuning quality for stationary motors.

[0009] Therefore, there is a need to provide an improved scheme for configuring a motor drive and an apparatus for implementing the scheme that addresses at least some of the above-mentioned shortcomings and deficiencies of conventional techniques in the prior art. Summary of the invention

[0010] It is an object of the subject disclosure to provide improved schemes for configuring motor drives and apparatus for implementing the same.

[0011] Another object of the subject disclosure is to provide an improved scheme for configuring a motor drive and an apparatus for implementing the scheme, for alleviating the above-mentioned disadvantages and shortcomings of conventional schemes. In particular, the proposed scheme for configuring a motor drive can be performed while the induction motor remains stationary.

[0012] A further object of the subject disclosure is to provide an improved scheme for configuring a motor drive and an apparatus for implementing the scheme, for alleviating the above-mentioned disadvantages and shortcomings of conventional schemes. In particular, the proposed scheme for configuring a motor drive can be performed while the induction motor remains stationary, and the proposed scheme can be performed with standard grade measurement equipment.

[0013] To achieve these objects and other advantages, and in accordance with the purpose of the subject disclosure, as embodied and broadly described herein, in one aspect of the subject disclosure, a method for configuring a motor drive is provided, the motor drive being used to drive an induction motor (e.g., an asynchronous induction motor). The method includes, for an induction motor including a rotor and a magnetic core including a magnetic induction component: performing N measurements of voltage at motor terminals of the motor when the motor is stationary during demagnetization of the magnetic core of the motor; determining an estimate of a magnetic induction component of the motor operating in a linear manner based on the N voltage measurements; determining an estimate of a time constant of a rotor of the motor operating in a linear manner based on one of the N voltage measurements; determining an estimate of a rotor resistance of the motor based on the estimate of the magnetic induction component of the motor and the rotor time constant.

[0014] The proposed method advantageously provides a solution that can be used to configure a motor drive in order to drive an induction motor coupled to the motor drive while keeping the motor drive at a standstill and using standard grade measurement equipment (in particular standard grade voltage measurement equipment that is not able to provide accurate measurements of measurement voltages below a certain threshold). This advantageously avoids starting the induction motor for the (sole) purpose of determining parameters of the motor drive corresponding to measurements performed on the motor drive and allows to perform a stationary tuning of the induction motor using standard grade measurement equipment.

[0015] In one or more embodiments, the proposed method may further include: configuring the motor drive based on an estimate of the rotor resistance of the motor.

[0016] In one or more embodiments, the proposed method may further include: before each voltage measurement, injecting a corresponding direct current DC current value into the stationary motor for a corresponding duration of magnetization of the motor's core, wherein the corresponding value of the DC current is one of a set of corresponding values ​​of DC current having different levels.

[0017] In one or more embodiments, the proposed method may further comprise, for each voltage measurement, determining an estimate of the magnetic flux in the magnetically inductive component of the electrical machine based on the voltage measurement.

[0018] In one or more embodiments, the proposed method may further include: determining N pairs of current and magnetic flux values ​​based on the further performed N voltage measurements to inject corresponding DC current values ​​into the motor in a stationary state in corresponding time periods.

[0019] In one or more embodiments, the proposed method may further include determining one or more parameters of a magnetic saturation model of a magnetic induction component of the electric machine based on the N pairs of current and magnetic flux values.

[0020] In one or more embodiments, the proposed method may further include: determining a magnetic saturation curve corresponding to a magnetic saturation model, the magnetic saturation model fitting N points corresponding to N pairs of current and magnetic flux values, respectively.

[0021] In one or more embodiments, a linear regression algorithm may be used to determine the magnetic saturation curve.

[0022] In one or more embodiments, an estimate of the time constant of the rotor may be determined based on one of the N voltage measurements using an exponential regression algorithm.

[0023] In one or more embodiments, the electric machine is an asynchronous induction motor.

[0024] In one or more embodiments, the one or more measurements of voltage include S voltage measurement data points (v i ) 1≤i≤S , S is a non-zero natural number.

[0025] In yet another aspect of the subject disclosure, a device is provided, the device comprising a processor, a memory operably coupled to the processor, and an interface for coupling to an induction motor driven by the device, wherein the device is configured to perform a method as provided in the subject disclosure.

[0026] In yet another aspect of the subject disclosure, a non-transitory computer-readable medium encoded with executable instructions is presented, which, when executed, causes an apparatus including a processor operably coupled to a memory to perform the method presented in the subject disclosure.

[0027] In yet another aspect of the subject disclosure, a computer program product comprising a computer program code tangibly embodied in a computer readable medium is provided, the computer program code comprising instructions that, when provided to a computer system and executed, causes the computer to perform the method provided in the subject disclosure. In another aspect of the subject disclosure, a data set representing the computer program provided herein, for example by compression or encoding, is provided.

[0028] It should be understood that the subject disclosure can be implemented and utilized in many ways, including but not limited to as a process, a device, a system, an apparatus, and as a method for applications now known and later developed. These and other unique features of the system disclosed herein will become more apparent from the following description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The subject disclosure will be better understood by those skilled in the art, and its numerous objects and advantages will become more apparent, by reference to the following drawings in conjunction with the accompanying description, in which:

[0030] Figure 1 An exemplary motor driver in a drive motor system to which the proposed method may be applied according to one or more embodiments is shown;

[0031] Figure 2 An exemplary model of a stationary induction motor that may be used in one or more embodiments of the subject disclosure is shown;

[0032] Figure 3 An exemplary scheme for configuring a motor drive according to one or more embodiments of the subject disclosure is shown;

[0033] Figure 4 illustrates an exemplary magnetic saturation model through four saturation model curves according to one or more embodiments;

[0034] Figure 5 shows an exemplary fitting curve of a magnetic saturation model according to one or more embodiments;

[0035] Figure 6a shows the magnetization of the main inductance L of an induction motor according to one or more embodiments, wherein a DC current is injected;

[0036] Figure 6b shows the demagnetization of the main inductance L of the induction motor according to one or more embodiments;

[0037] Figure 7 shows an exemplary voltage-time curve illustrating a demagnetization process of a motor core of an induction motor according to one or more embodiments;

[0038] Figure 8 illustrates an apparatus according to one or more embodiments; and

[0039] Fig. 9 The performance of the proposed method is shown. DETAILED DESCRIPTION

[0040] For simplicity and clarity of explanation, the accompanying drawings illustrate the general manner of construction, and the description and details of known features and technologies may be omitted to avoid unnecessarily obscuring the discussion of the embodiments of the present invention. In addition, the elements in the accompanying drawings are not necessarily drawn to scale. For example, the sizes of some elements in the drawings may be exaggerated relative to other elements to help improve the understanding of the embodiments of the present invention. To help understand, some figures may be shown in an idealized manner, such as when the structure is shown as having straight lines, acute angles and / or parallel planes, etc., under real-world conditions, these structures may be significantly less symmetrical and orderly. The same reference numerals in different drawings represent the same elements, and similar reference numerals may but do not necessarily represent similar elements.

[0041] In addition, it should be clear that the teachings herein can be implemented in multiple forms, and any specific structure and / or function disclosed herein is merely representative. Specifically, it will be understood by those skilled in the art that an aspect disclosed herein can be implemented independently of any other aspect, and several aspects can be combined in various ways.

[0042] The present disclosure is described below with reference to the functions, engines, block diagrams, and flow charts of the methods, systems, and computer programs according to one or more exemplary embodiments. Each described function, engine, block of the block diagram, and flow chart illustration may be implemented in hardware, software, firmware, middleware, microcode, or any suitable combination thereof. If implemented in software, the blocks of the functions, engines, block diagrams, and / or flow chart illustrations may be implemented by computer program instructions or software codes, which may be stored or transmitted via a computer-readable medium, or loaded onto a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, such that the computer program instructions or software codes executed on the computer or other programmable data processing device create a device for implementing the functions described herein.

[0043] Embodiments of computer-readable media include, but are not limited to, computer storage media and communication media, including any medium that is convenient for transferring a computer program from one place to another. As used herein, "computer storage media" can be any physical medium that can be accessed by a computer or processor. In addition, the terms "memory" and "computer storage media" include any type of data storage device, such as, but not limited to, a hard disk drive, a flash drive or other flash memory device (e.g., a storage key, a memory stick, a key drive, an SSD drive), a CD-ROM or other optical storage device, a DVD, a disk storage or other magnetic storage device, a memory chip, a random access memory (RAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a smart card or any other suitable medium, which can be used to carry or store program code in the form of an instruction or data structure that can be read by a computer processor, or a combination thereof. In addition, various forms of computer-readable media can transmit or carry instructions to a computer, including routers, gateways, servers or other wired (coaxial cable, optical fiber, twisted pair, DSL cable) or wireless (infrared, radio, cellular, microwave) transmission equipment. The instructions may include code from any computer programming language, including but not limited to Assembly, C, C++, Python, Visual Basic, SQL, PHP, and JAVA.

[0044] Unless otherwise indicated, it will be understood that throughout the following description, discussions using terms such as processing, computing, calculating, determining, etc. refer to the actions or processes of a computer or computing system or similar electronic computing device that manipulates or transforms data represented as physical quantities (e.g., electronic quantities) within the computing system's registers or memories into other data similarly represented as physical quantities within the computing system's memories, registers, or other such information storage, transmission, or display devices.

[0045] As used herein, the terms "comprises," "comprising," "including," "having," and any variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0046] Additionally, the word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0047] In the subject disclosure, the terms "coupled" and "connected" and their derivatives may be used indiscriminately to indicate that two or more elements are either in direct physical or electrical contact with each other, or that two or more elements are not in direct contact with each other but yet still co-operate or interact with each other.

[0048] It will be appreciated that embodiments of the subject disclosure may be used to configure an induction motor drive configured to drive an induction motor, and in particular, although not limited to, an induction motor drive configured to drive an asynchronous induction motor.

[0049] Figure 1 An exemplary motor drive in a drive motor system (1) to which the proposed method may be applied according to one or more embodiments is shown.

[0050] Figure 1 A drive motor system (1) is shown, comprising a motor drive (2) and an induction motor (3), which are operably coupled to each other via an interface (4).

[0051] The induction motor (3) comprises a rotor (3a) and a magnetic core (3b), the magnetic core comprising a magnetic induction component (not shown in the figure), sometimes referred to as the "main induction" of the induction motor (3).

[0052] In some embodiments, a so-called "motor tuning" phase may be performed for determining configuration parameters of the motor driver (2) corresponding to the characteristics of the induction motor (3) so that the motor driver (2) is tuned for driving the induction motor (3).

[0053] Depending on the embodiment, the motor driver (2) can be implemented using software as described above, or using hardware such as an application specific integrated circuit (ASIC), or in the form of a combination of hardware and software, such as a software program loaded and executed on an FPGA (field programmable gate array) type component.

[0054] Since the proposed method is intended for configuring an induction motor drive coupled to a stationary induction motor, a model of the stationary induction motor may advantageously be considered.

[0055] Figure 2 An exemplary model of a stationary induction machine that may be used in one or more embodiments of the subject disclosure is shown.

[0056] Figure 2 An exemplary inverse Γ model of a stationary induction machine is shown.

[0057] The stationary induction motor is simulated by a dipole circuit (3) to which a voltage Vs can be applied to start the motor. The model comprises a first block (3b) simulating the stator of the motor (3), the first block being connected in series to a second block (3a) simulating the rotor of the motor (3). Figure 1 In the example shown, the first block (3b) includes the leakage inductance L f Stator resistor R connected in series sThe second block (3a) comprises a rotor resistor R connected in parallel with the main inductance L of the motor (3) r .

[0058] like Figure 2 As shown, the current i injected into the motor (3) s It flows through the first block (3b) and then through the main inductance L of the motor (3). The current i s and the current flowing through the rotor resistance R r The current summation i r , generating a current i=i flowing through the main inductance L of the motor (3) s +i r (Nodes at which current flows into and out of a circuit according to Kirchhoff's circuit laws).

[0059] Assuming the induction motor is at rest, the following system of equations can be obtained from Figure 2 Export from the model:

[0060] Equation along the d-axis:

[0061]

[0062] Where V sd is the input voltage V s The projection on the d axis, R s is the stator resistance, i sd is the projection of the current injected into the motor on the d-axis, L f is the stator leakage inductance, R r is the rotor resistance, i rd is the current flowing through the rotor resistance R r The current i r The projection on the d axis is The current i = i sd +i rd The magnetic flux generated by the main inductance L of the rotor Projection onto the d-axis.

[0063] Equation along the q-axis:

[0064]

[0065] Where V sq is the input voltage V s The projection on the d axis, R s is the stator resistance, i sq is the current injected into the motor s Projection on the d axis, L f is the stator leakage inductance, R r is the rotor resistance, i rq is the current flowing through the rotor resistance r r The current ir The projection on the d axis is The current i = i sq +i rq The magnetic flux generated by the main inductance L of the rotor Projection onto the d-axis.

[0066] As shown above, the equations along the d-axis and the q-axis represent two identical systems, one along the d-axis and the other along the q-axis, with no connection between them. Therefore, each of these two systems can be modeled as an inverse Γ induction motor model, such as Figure 2 Example model shown.

[0067] Therefore, the proposed scheme can be described using this exemplary model applied to one or the other axis, so that the equations for one or the other axis can be used indifferently, since the proposed scheme can be used with either set of equations. In the following, as an example, the above set of equations corresponding to the frame oriented along the d-axis will be used so that the model used can be reduced to an inverse circuit.

[0068] In the following, based on Figure 2 An exemplary model of an induction motor at rest is used, assuming that the frame is oriented along the d-axis, to describe the proposed solution. However, those skilled in the art will appreciate that although the present specification uses the inverse Γ model of a stationary induction motor with a frame oriented along the d-axis as an example of a stationary induction motor model that can be used in one or more embodiments, the inverse Γ model of a stationary induction motor with a frame oriented along the q-axis can be used to replace the inverse Γ model of a stationary induction motor with a frame oriented along the d-axis, which is given only as an example.

[0069] In addition, in the following, based on Figure 2 The proposed solution is described using an exemplary model of an induction motor at rest. However, those skilled in the art will appreciate that although the present specification uses the inverse Γ model of a stationary induction motor as an example of a model of a stationary induction motor that can be used in one or more embodiments, any other suitable model of a stationary induction motor can be used instead. Figure 2 The inverse Γ model of a stationary induction motor is given as an example only.

[0070] Return to reference Figure 1 and 2 In one or more embodiments, at least one configuration parameter of a motor driver (2) for configuring a motor (3) for driving an induction motor (3) can be determined by determining a rotor resistance R of the induction motor (3). r to obtain an estimate.

[0071] The proposed solution thus advantageously provides a method for determining the rotor resistance R of an induction motor (3) based on voltage measurements while keeping the motor stationary. r This voltage measurement can be performed with standard grade measurement equipment.

[0072] Figure 3 is a schematic diagram illustrating an exemplary scheme (10) for configuring a motor drive according to one or more embodiments of the subject disclosure.

[0073] Consider a motor drive coupled to an induction motor such as Figure 1 As shown, for the motor drive, data related to configuration parameters that can be used to configure the motor drive to drive the motor can be determined according to the proposed scheme.

[0074] In some embodiments, the motor coupled to the motor drive may be modeled by a stationary induction motor model, for example, Figure 2 The examples are described.

[0075] In addition, if Figure 1 and Figure 2 As shown, the motor driven by the motor drive once configured may include a rotor and a magnetic core including a magnetic induction component.

[0076] In one or more embodiments, (10)N (e.g., N=10) voltage measurements at the motor terminals when the motor is stationary may be performed during respective measurement cycles from the initial magnetic flux of the motor's core to the demagnetization of the motor's core (during the time period during which the core demagnetization phenomenon occurs).

[0077] In some embodiments, the measurement of one or more voltages may be performed during initial demagnetization of the core of the electric machine, ie, during an initial portion of a period of time during which the core is magnetized at an initial flux value during which demagnetization of the core further occurs.

[0078] In some embodiments, the one or more voltage measurements performed during a respective voltage measurement cycle may include S voltage measurement data points (v i ) 1≤i≤S , S is a non-zero natural number.

[0079] For example, in some embodiments, for one or more voltage measurements, S voltage measurement data points (v i ) 1≤i≤S It can be obtained by voltage measurement sampling with a sampling interval (Δt). In such an embodiment, the voltage at the motor terminals can be measured during a voltage measurement period that is substantially equal to the product of the number of voltage samples and the sampling interval S·Δt.

[0080] In some embodiments, th Before voltage measurement (1≤j≤N), the DC current i j The corresponding value can be found in the corresponding duration t of the magnetization (magnetization phase) of the motor core. j Preferably, the DC current i j The corresponding value of may be one of a set of corresponding values ​​of DC currents having different levels. For example, in order to perform N voltage measurements, N DC current injections (i j ) 1≤j≤N , the current level is different (for 1≤j1≠j2≤N, i j1 ≠i j2 ).

[0081] In one or more embodiments, N voltage measurements may be used to determine (12) an estimate of the magnetic inductance (L0) of the motor (main inductance of the motor) operating in a linear phase (linear state) (the motor magnetic inductance during the linear operating phase of the motor).

[0082] In one or more embodiments, one of the N voltage measurements may also be used to determine (13) an estimate of a rotor time constant (τ0) of the motor rotor operating in a linear phase (linear state) (the time constant of the motor rotor during the linear operation phase).

[0083] In one or more embodiments, the rotor resistance (R ) of the motor may be determined (14) based on an estimate of the motor's magnetic induction coefficient (L 0 ) and rotor time constant (τ 0 ). r )’s estimate.

[0084] For example, in some embodiments, the estimated value of the rotor resistance (R r ) can be determined based on the ratio of the estimated magnetic induction coefficient (L0) of the motor to the estimated rotor time constant (τ0).

[0085] In one or more embodiments, the motor driver can be configured to determine the rotor resistance (R r ) is estimated to drive the induction motor.

[0086] In one or more embodiments, by having selected a stationary induction motor model as the model of the induction motor to be driven, the magnetic saturation of the magnetic core of the motor to be driven and the injection of DC current into the motor can be considered in the proposed solution. Figure 2 , Figure 2 The main inductance L in the inverse Γ model circuit shown may experience magnetic saturation, so that the magnetic flux of the magnetic core generated by injecting DC current into the motor may increase with increasing injection current value until reaching a certain upper limit value corresponding to the saturation magnetic flux value. That is to say, Figure 4 As shown, for values ​​above a certain value of the injected current, the current i input to the motor and the magnetic flux generated by the motor core The relationship between is not linear.

[0087] In one or more embodiments, the magnetic saturation model can therefore be advantageously considered in order to distinguish between an induction motor operating in a linear regime (without magnetic saturation of the magnetic core) and an induction motor operating in a saturation regime (with magnetic saturation of the magnetic core), for example, to capture the parameters or characteristics of a motor operating in a linear phase (linear regime) and the parameters or characteristics of a motor operating in a magnetic saturation phase (saturation regime). It is indeed advantageous to configure the drive to drive the motor with one or more current values ​​that do not trigger magnetic saturation of the motor core.

[0088] In some embodiments, a core magnetization model that takes into account the magnetic saturation of the core (sometimes referred to herein as a "magnetic saturation model"), which defines the relationship between the current injected into the induction motor and the flux value in the main inductance of the induction motor, can be considered to estimate the parameters of the induction motor, which characterize the motor operating in the linear stage (linear state) (relative to the motor operating in the magnetic saturation stage (saturation state)).

[0089] For example, in some embodiments, the following magnetic saturation model of an induction motor Can be used to characterize a motor operating in the linear phase (linear state):

[0090]

[0091] in represents the maximum magnetic flux that can be induced in the core (which can be regarded as corresponding to the magnetic saturation magnetic flux generated by the main inductance assuming infinite current is injected into the motor), L0 represents the linear inductance before saturation (which can be regarded as corresponding to the value of the main inductance of the motor operating in the linear phase (linear state)) (relative to the motor operating in the magnetic saturation phase (saturation state)), and γ represents a unitless shape factor affecting the magnetic flux value at which the magnetization switches from the linear state to the saturation state.

[0092] The transition flux value can be equal to

[0093] Thus, in some embodiments, the magnetic saturation model may be a parametric model with three parameters (e.g., in the exemplary case of the above model: L0 and γ).

[0094] Figure 4 By respectively corresponding to the four γ parameter values ​​of the saturated model (the other two parameters have fixed values: and L0=250mH) to illustrate the magnetic saturation model.

[0095] In the following, based on the three parameters L0 and γ controlled Figure 4 The proposed solution is described using an exemplary parameter magnetic saturation model of an induction motor at rest. However, a person skilled in the art will appreciate that even though the present description refers to the parameters of the exemplary magnetic saturation model, any other suitable magnetic saturation model of an induction motor may be used instead. Figure 4 Parametric magnetic saturation model of a stationary induction motor, which is given as an example only.

[0096] In one or more embodiments, N voltage measurements at the motor terminals of a stationary motor during demagnetization of the motor's core may be used to determine estimated values ​​for parameters of a magnetic saturation model selected to implement the proposed scheme.

[0097] In one or more embodiments, for each of the N voltage measurements, during demagnetization of the core of the motor, a plurality of voltage data points may be measured, further DC injection may be performed, i.e., a DC current is injected into the motor at rest for magnetizing the core to a so-called initial flux level. In some embodiments, a certain current may be injected for a given period of time in order to magnetize the inner core of the motor, and then the circuit may be disconnected and voltage measurements may be performed on the disconnected circuit. The induced voltage during demagnetization may be analyzed in order to obtain an estimate of the flux generated by the DC injection.

[0098] For each of the N voltage measurements, the determined estimate of the initial magnetic flux can be used in some embodiments to generate a pair of where i is the DC current injected into the motor to magnetize the core, and is the magnetic flux of the core produced by its magnetization.

[0099] For example, in an embodiment using the magnetic saturation model described above, N voltage measurements at the motor terminals of a stationary motor during demagnetization of the motor's core can be used to determine estimates of the three parameters of the magnetic saturation model, since such a model consists of three parameters: L0, and γ control.

[0100] In one or more embodiments, the number N of voltage measurements performed to determine parameter estimates for a selected magnetic saturation model may be selected to be greater than or equal to the number of magnetic saturation model parameters to be estimated.

[0101] In one or more embodiments, N may be selected to be greater than or equal to three (N≥3) based on the magnetic saturation model used being controlled by three parameters.

[0102] In some embodiments, each voltage measurement is performed during demagnetization of the core of the motor, further injecting current into the motor at rest to magnetize the core.

[0103] For example, N voltage measurements may be performed, and the N voltage measurements (V sj ) 1≤j≤N Each of the previous can inject a DC current i of its own level j , so we can determine N pairs (i j ,V sk ) 1≤j≤N The injected DC current value and the measured voltage value.

[0104] In one or more embodiments, each voltage measurement V sj can be further used to determine the corresponding flux value of the magnetic flux in the main inductance of the motor, so that it can be based on N voltage measurements (V sj ) 1＜i＜N To determine the N magnetic flux values

[0105] In some embodiments, based on the further N voltage measurements (V sj ) 1≤j≤N , N magnetic flux values Can be used to determine N pairs The injected DC current and magnetic flux values ​​are used to inject corresponding DC current values ​​into the motor at rest within corresponding time periods.

[0106] In some embodiments, N pairs The injected DC current and magnetic flux values ​​can be used as N injection points It can be advantageously used to determine the best fit saturation curve for a selected magnetic saturation model.

[0107] Depending on the embodiment, any suitable fitting method may be used to fit the magnetic saturation model to the experimental data (injection point For example, if more than N (eg, N=3) injection points are used to fit a magnetic saturation model controlled by N parameters, a least squares method may be applied to fit the model on the experimental data.

[0108] In some embodiments, a linear regression algorithm may be applied to fit the N injection points on the magnetic saturation model in order to determine corresponding estimates of the parameters corresponding to the linear range of the saturation model.

[0109] In one or more embodiments, the equation defining the magnetic saturation model is can be reformulated in a linear fashion so that the measured data (N injection points Apply a linear regression algorithm.

[0110] For example, the equation

[0111]

[0112] It can be restated as follows:

[0113]

[0114] So we can estimate the three coefficients and In order to determine the three parameters Estimates of L0, and γ.

[0115] In an embodiment using a linear regression algorithm for N injection points, the following matrices A and B may be calculated to perform linear regression:

[0116]

[0117] and

[0118]

[0119] The matrix orders of A and B are determined by 1≤j≤N.

[0120] In some embodiments, to obtain the three coefficients and The matrix product A of the inverse matrix of matrix A and matrix B can be determined -1 B, as follows:

[0121]

[0122] In one or more embodiments, to calculate the matrix product A -1 For each of the three elements of the vector produced by B, the matrix determinant of the matrix A can be calculated, based on which the following three matrix determinants can be calculated:

[0123]

[0124]

[0125]

[0126] Based on the above matrix determinant, the magnetic saturation model parameters can be calculated The corresponding estimates of L0, and γ.

[0127] In particular, in some embodiments, an estimate of the magnetic induction component L0 of a motor operating in a linear manner may be determined based on one or more of the above matrix determinants, wherein the elements of the matrix determinant may be determined based on N voltage measurements performed on a stationary motor.

[0128] Figure 5 An exemplary fitting curve of the magnetic saturation model calculated based on magnetic saturation model parameters is shown, wherein the magnetic saturation model parameters are based on the six current flux pairs corresponding to each other. The six injection points are estimated.

[0129] Figure 5 Injection point shown The magnetization curve of the magnetic saturation model and the estimated magnetization curve can be used to calculate the parameters L0, and γ. Figure 5 In the example shown, the theoretical values ​​of the magnetic saturation model parameters are: L0 = 250mH, γ=0.3, and the values ​​estimated using the proposed saturation model fitting method are: L0=215mH, γ=0.5.

[0130] Therefore, in one or more embodiments, the current and flux values ​​can be calculated based on N To determine estimated values ​​of one or more parameters of a magnetic saturation model of the magnetic inductance of the electric machine.

[0131] In one or more embodiments, N respective DC current injections may be performed in a stationary motor prior to performing voltage measurements to magnetize the motor's core prior to disconnecting the motor's circuit, and N respective voltage measurements may be performed on an open circuit (at the motor's terminals) during core demagnetization.

[0132] For example, in some embodiments, during demagnetization of the core of the motor, each of N voltage measurements at the motor terminals when the motor is stopped can be performed after a DC current injection of a corresponding value of the DC current when the motor is stopped for a corresponding DC injection duration, so that when the N voltage measurements are performed, the core of the motor can be magnetized to the initial magnetic flux.

[0133] In some embodiments, the corresponding time period (Δt j ) 1≤j≤N The corresponding level (i j ) 1≤j≤N Perform N DC current injections so that the core of the motor can be magnetized at a certain level, such as Figure 6a shown.

[0134] Figure 6a shows that the DC current Iinj Injection induction motor (by Figure 2 1 ), in order to generate magnetization of the main inductance L of the motor, that is, to generate an initial magnetic flux in the main inductance L of the motor. During the DC current injection, the main inductance L of the motor is magnetized at a magnetic flux level that depends on one or more of the level of the injected DC current and the duration of the DC current injection.

[0135] refer to Figure 2 and Figure 6a , the DC current I inj During the injection into the motor, the current i s The stator resistance R that can be connected in series s and leakage inductance L f piece( Figure 2 3b) and the main inductance L of the motor, and no current can flow in the rotor resistance R of the motor. r When a constant voltage is applied to the terminals of the motor, the input current may eventually stabilize in the main inductance L after a certain period of time.

[0136] In some embodiments, different levels of DC current (i j ) 1≤j≤N Injected into the motor, thus generating correspondingly different levels of magnetic flux at the main inductance L (core) of the motor

[0137] In one or more embodiments, once the DC current injection stops, the circuit of the motor can be disconnected at the positive and negative poles, and the voltage V at the motor terminals corresponding to the poles of the motor at rest can be measured. meas .

[0138] Figure 6b It shows that once the DC current I is no longer injected inj And the motor circuit is disconnected, the main inductance L of the motor is demagnetized (by Figure 2 Example inverse Γ model modeling of a stationary induction motor shown).

[0139] refer to Figure 2 and Figure 6b , once the DC current I inj No longer fed into the motor and the circuit is open, the current i s The stator resistance R that may no longer be connected in series s and leakage inductance L f piece( Figure 2 3b) and the main inductance of the motor, and the current (induced by the magnetized core of the motor) may instead flow in the parallel-connected rotor resistance R rand the main inductance L of the motor. Once the circuit is disconnected, the main inductance L and the rotor resistance R r The demagnetization process between the two starts from the initial magnetic flux (corresponding to the magnetic flux level reached by the core magnetization, for example, by the previous DC injection). At this time, the measured voltage V meas corresponds to the voltage across the main inductance L, since no current flows through the stator resistance R s and leakage inductance L f :

[0140]

[0141] Therefore, the voltage measurement V at the motor terminals meas It can advantageously reflect the magnetic flux of the motor main inductance L

[0142] During the demagnetization process, the magnetic flux in the motor core can be controlled by the following differential equation:

[0143]

[0144] Figure 7 A voltage-time curve illustrating the demagnetization process of the motor core is shown. Figure 7 The exemplary curve of shows the evolution of the measured voltage over time during demagnetization of the motor core.

[0145] Figure 7 An exemplary demagnetization curve for the following parameters of the exemplary induction motor model and the exemplary magnetic saturation model discussed herein is shown: γ = 0.3, L0=250mH、R r =500mΩ, and the initial magnetic flux value

[0146] like Figure 7 As shown in Figure 1, the magnetic saturation effect of the motor core can be reflected at the beginning of the core demagnetization process, because the core may have reached its saturation level during the magnetization process. Figure 7 As shown, the measured voltage may decrease linearly with time from the initial value, whereas in the absence of saturation of the core it will decrease exponentially with time.

[0147] like Figure 7 As shown, the saturation effect occurs in about half a second (t sat ≈0.5s) is reflected in the measured voltage (however, the measured voltage can accurately reflect the demagnetization process without saturation afterwards (from t sat That is, assuming that the demagnetization process lasts for a given demagnetization duration (in Figure 7 In the example shown, Δt DemagThe saturation effect that occurs during the core magnetization period can be reflected in the demagnetization duration (Δt Demag ) in its early stages (in Figure 7 In the example from t = 0 to t = t sat ) is performed during the voltage measurement portion, and during the remainder of the demagnetization process (from t sat to Δt Demag The voltage measurement section will no longer appear in the end of the operation.

[0148] Various methods may be used to estimate the magnetic flux value of the motor core once further magnetized to DC current injection, the magnetic flux value corresponding to each of one or more of the N voltage measurement values. For example, in one or more embodiments, an integral analysis voltage measurement processing method may be used to integrate the value of the measured voltage over a time period over which the corresponding voltage measurement is performed, which may produce a first magnetic flux estimate component. As another example, an exponential regression analysis voltage measurement processing method may be used to fit an exponentially decreasing curve of the voltage measurement.

[0149] In one or more embodiments, another method may be used, which may be considered a hybrid method because it uses both an integral method and an exponential regression analysis method, which advantageously exploits the fact that the magnetic saturation of the core is reflected in the voltage measurement only for the early part of the demagnetization process, while after the end of the early part until the end of the demagnetization process, the voltage decreases according to an exponential decay curve reflecting the demagnetization. Therefore, in such an embodiment, two consecutive time periods of the demagnetization process may be distinguished based on the presence of the magnetic saturation effect reflected in the voltage measurement: a first initial time period at the beginning of demagnetization, during which the measured voltage may be considered to be affected by the magnetic saturation of the core, and a second subsequent time period after the first time period until the end of the demagnetization, during which the measured voltage may be considered to be no longer affected by the magnetic saturation of the core. In the following, the first time period may be referred to as the "first time period showing saturation", while the second time period may be referred to as the "second time period without saturation".

[0150] In one or more embodiments, instead of using the integration method until the demagnetization process is complete, that is, until the demagnetization duration (Δt Demag ) ends, which will require collecting the entire demagnetization duration (Δt Demag ) to perform voltage measurement so as to estimate the initial magnetic flux of the core by integrating the value of the measured induced voltage until the demagnetization process is completed (e.g., during the entire demagnetization duration (Δt Demag ) the collected voltage data points are integrated over a period of time), the integration method may be used only during the first time period showing saturation.

[0151] In some embodiments, an integration method may be used for voltage measurements, which are performed only during a voltage measurement period during the initial demagnetization of the motor core. The voltage measurement period during which the voltage measurement is performed may be preconfigured to correspond to a specific first time period that indicates saturation of the motor during which the voltage measurement is performed. Thus, the voltage measurement may advantageously not be performed until the end of the demagnetization process, but only during a voltage measurement period corresponding to an initial portion of the demagnetization process and being shorter than the entire demagnetization process.

[0152] In some embodiments, the voltage measurement can be configured to start at the initial stage of the demagnetization process (in the early stages of demagnetization) and end before the end of the demagnetization process. Therefore, the voltage measurement can result in the voltage measurement data points covering only the initial part of the demagnetization process (in the early stages of demagnetization).

[0153] Thus, the integration method applied to the voltage measurements (data points) may result in integrating the measured induced voltage over a period spanning an initial time at which the voltage measurement begins to the end of the voltage measurement cycle, rather than integrating the measured voltage until the end of demagnetization.

[0154] Depending on the embodiment, the voltage at the motor terminals may or may not be measured before the end of the demagnetization process, so that for the purpose of applying the integration method, voltage measurement data points that may have been acquired after the end of the voltage measurement period may be ignored. Thus, only voltage measurement data points acquired during the voltage measurement period may be used for the purpose of applying the integration method.

[0155] Return to reference Figure 7 , it is advantageous to apply the integration method using only the voltage measurement data points acquired during a voltage measurement cycle configured during the initial demagnetization of the core of the electric machine (in the early stages of the demagnetization process of the core), since it avoids applying this integration method to the voltage values, since this reflects the later part until the end of the demagnetization of the core, which may be low and subject to inaccurate measurements depending on the measurement equipment used to perform the voltage measurement (for example, in the case of using standard grade voltage measurement equipment with limited accuracy performance for low voltage values). In fact, when applying the integration method that may accumulate during the magnetic decay, performing the voltage measurement with limited accuracy will generate errors, which are proportional to the integration duration. Therefore, the proposed solution has the advantage of avoiding the use of the integration method for too long an integration duration, since it uses the measurement data points corresponding to the early stages of demagnetization and therefore does not suffer from measurement errors that can be detrimental to the accuracy of the estimate obtained with the integration method. By using the integration method only on the voltage measurement data points captured during the initial part (early stages) of the demagnetization process, the captured values ​​can be considered high enough so that measurement errors can be avoided or at least reduced even in the case of using standard grade measurement equipment.

[0156] In one or more embodiments, because the integration method is only used for voltage measurement data points acquired during a voltage measurement period that is shorter than the entire demagnetization process duration, it may result in a magnetic flux estimate that is a component of the magnetic flux that would be estimated if the integration method had been applied to the entire demagnetization process duration. Therefore, a first magnetic flux estimate component may be determined based on the voltage measurement, such as by using the integration method applied to voltage measurement data points acquired during the voltage measurement period.

[0157] In some embodiments, an integration method may be used to integrate the voltage measurement values ​​within a voltage measurement period so as to integrate the measured voltage value induced by demagnetization before the end of the voltage measurement period, which advantageously falls before the end of the demagnetization process.

[0158] In some embodiments, for each of one or more of the N voltage measurements, the voltage measurement for the voltage measurement cycle may include S voltage measurement data points (v i ) 1≤i≤S , S is a non-zero natural number, and S voltage measurement data points (v i ) 1≤i≤S One or more of may be integrated to obtain a first magnetic flux estimate component.

[0159] For example, after obtaining S voltage measurement data points (v i ) 1≤i≤S In an embodiment of the present invention, the first magnetic flux estimation component can be based on the sampling interval and one or S voltage measurement data points (v i ) 1≤i≤S The combination of combinations is determined, for example,

[0160] According to the subject disclosure, in addition to the integration method, a second method can be used to determine the portion of the initial magnetic flux that is not accounted for by integrating the induced voltage over only a portion of the demagnetization process duration. In one or more embodiments, a regression method (e.g., an exponential regression method) can be used for this purpose. The use of an exponential regression method is advantageous in the exemplary context of the subject disclosure focusing on the demagnetization process of the magnetic core of an induction motor, because such a demagnetization process typically follows an exponential decay curve, e.g. Figure 7 The curve shown.

[0161] As mentioned above, during the demagnetization process, the magnetic flux in the motor core can be controlled by the following differential equation:

[0162]

[0163] In some embodiments, in order to approximate the magnetization to be linear, a small amount of magnetic flux can be neglected. This leads to the following simplified version of the above differential equation:

[0164]

[0165] because

[0166] The following function is the solution of the above simplified equation:

[0167]

[0168] in is the rotor time constant of the motor rotor operating in linear mode. Therefore, during demagnetization, the magnetic flux of the injection motor core decreases exponentially, which is controlled by the time constant τ0, which corresponds to the rotor time constant of the motor rotor operating in linear mode.

[0169] Thus, in some embodiments, N DC voltage measurements at the motor terminals (which in some embodiments may respectively correspond to N DC current injections) during core demagnetization of the motor may be advantageously used for two different purposes:

[0170] First, as described above, an estimate of the magnetic induction of the motor operating in the linear phase L0 can be determined based on the N voltage measurements, for example by using N data points determined based on the N voltage measurements. Saturation model fitting method: By implementing different levels of DC current injection, Each injection may advantageously provide a value for the flux in the main inductance L after integration.

[0171] For example, in one or more embodiments, one or more of the N measured voltages (at the motor terminals of a stationary motor during demagnetization of the motor's core) may be integrated over time to determine the motor's core (e.g., Figure 2 The corresponding estimate of the magnetic flux in the main inductance L)

[0172]

[0173] Where V meas,j (t) is the jth voltage measured at the motor terminals at rest during the demagnetization of the motor core, which can follow the jth DC current i j Injected into the motor to magnetize the core.

[0174] In some embodiments, in addition to determining the DC current corresponding to the jth DC current i jThe jth estimated magnetic flux injected In addition, N data points can be determined The jth magnetic flux in the core is based on the jth DC current i in the motor. j It is estimated from the jth voltage measured at the motor terminals when the motor is stationary during the demagnetization of the motor core after injection.

[0175] In some embodiments, N data points A fitting algorithm for applying a magnetic saturation model, such as the linear regression described above for the exemplary magnetic saturation model described above, may be used to estimate a set of one or more parameters of the magnetic saturation model, including an estimate of the magnetic induction coefficient (L0) of the motor operating in a linear manner.

[0176] In one or more embodiments, where a hybrid method of determining core flux estimation by DC current injection magnetization is used, using an exponential regression method may include fitting an exponentially decreasing curve on voltage measurement data points acquired during a voltage measurement period.

[0177] The second magnetic flux estimate component may then advantageously be derived mathematically from the obtained fitting parameters.

[0178] Using an exponential regression method is advantageous because this method is not affected by measurement errors because it forces the voltage curve to fit a perfect exponential curve. However, the exponential regression method assumes magnetic linearity and tends to perform poorly under magnetic saturation.

[0179] Therefore, the exponential regression method is a good complement to the integral method because it performs well for voltage measurements where the integral method is not suitable (because the integral method is sensitive to measurement errors that may occur when measuring small voltage values ​​at the end of the demagnetization process) and vice versa (because the exponential regression method causes errors in the initial (early) stages of demagnetization when core magnetic saturation occurs).

[0180] Thus, in some embodiments, an integral method may be used to determine a first magnetic flux estimate component based on voltage measurements performed only over a portion of the demagnetization process of the magnetic core of the induction motor, and an exponential regression method may be used to determine a second magnetic flux estimate component, which, combined with the first magnetic flux estimate component, will provide an estimate of the magnetic flux of the magnetic core at the beginning of demagnetization.

[0181] In one or more embodiments, for the purpose of applying the exponential regression method, an estimate of the rotor time constant τ0 of the motor rotor operating in a linear manner may be determined based on one of the N voltage measurements:

[0182] In one or more embodiments, exponential regression may be used to estimate a time constant value for a motor rotor operating in a linear manner based on one of N voltage measurements.

[0183] Return to reference Figure 6b , in the motor's magnetic core ( Figure 6b The voltage V measured at the motor terminals during demagnetization of the magnetically inductive component L on the motor meas This demagnetization can be reflected by the following exponential decrease over time:

[0184]

[0185] Where V0 is the voltage value measured at t=0, and τ0 is the time constant of the motor rotor.

[0186] like Figure 7 As shown, for the initial measurement of the voltage (in the example of this figure, the measurement duration is shorter than 0.3 seconds), the magnetic core of the motor may experience magnetic saturation. sat_threshold ), the voltage measurement performed corresponds to the linear state of the motor (ie, the core is not magnetically saturated).

[0187] Thus, in some embodiments, one or more voltage measurements (at the motor terminals of a stationary motor during demagnetization of the motor's core) may advantageously be performed for a corresponding time measurement duration. In some embodiments, a time measurement duration may be predefined for one or more voltage measurements, for example based on a theoretical value of a rotor time constant of the motor. For example, the time measurement duration of one or more voltage measurements may be predefined as a multiple (e.g. 8) of the theoretical value of the rotor time constant of the motor.

[0188] In one or more embodiments, one or more of the N voltage measurements (at the motor terminals of a stationary motor during core demagnetization of the motor) can be used to determine an estimate of the rotor time constant τ0. The duration of one or more of the N voltage measurements can be determined such that the voltage measurements can be used to determine an estimate of the rotor time constant during core demagnetization, as well as to determine the magnetic flux in the motor core during core demagnetization as described above. An estimate of (e.g., by integrating the measured voltage over a duration).

[0189] In one or more embodiments, for each of one or more of the N voltage measurements, the voltage measurements of the voltage measurement cycle may generate S voltage measurement data points (v i ) 1≤i≤S, S is a non-zero natural number. In some embodiments, the voltage measurement data points are obtained by measuring and sampling with a sampling interval (Δt). Therefore, in some embodiments, the S pairs of voltage measurement data points v in the voltage measurement cycle are i and the corresponding voltage measurement data point v i The acquisition time t i The S voltage measurement data points (v) included in the voltage measurement of the voltage at the motor terminals of a stationary motor during the (initial) part of the demagnetization of the motor's core can be i ) 1≤i≤S In some embodiments, the voltage measurement period may correspond to a time interval t S In some embodiments, S data points (t i ,v i ) 1≤i≤S .

[0190] In some embodiments, to estimate the value of the rotor time constant during linear magnetization, an exponential regression may be applied, preferably once the voltage is linear (during the linear regime of the motor), since exponential regression can be used to apply to log(v i ) data.

[0191] To use exponential regression on a data set, in some embodiments, the logarithm of one or more data points of the data set may be determined, such as S voltage measurement data points (v i ) 1≤i≤S in order to apply the linear regression algorithm.

[0192] In some embodiments, a set of S time-voltage data points (t i ,v i ) 1≤i≤S is an exponential fit, with duration t i and voltage variable v i There is an exponential relationship between them, for example:

[0193]

[0194] where V0 is the initial voltage measurement at t=0, and τ0 is the time constant.

[0195] Take v i The logarithm of

[0196]

[0197] In some embodiments, linear regression can therefore be applied to a logarithmic data set (t i ,logv i )1≤i≤N , for example using the following equation:

[0198]

[0199] and

[0200]

[0201] Therefore, in some embodiments, the estimate of the rotor time constant τ0 is This can be determined based on:

[0202]

[0203] According to an embodiment of the proposed solution, the inner core is in a linear magnetization state (eg Figure 7 As shown, the advantage of a demagnetization process phase following a short magnetic saturation phase of the core over such a magnetic saturation phase will minimize the impact of having some data points that can be selected from before fully entering the magnetic linear region, which advantageously gives greater robustness to the estimation of the rotor time constant.

[0204] In one or more embodiments, where the hybrid method described above for estimating the magnetic flux of the magnetic core is used, the second magnetic flux estimate component may be based on an estimate of the rotor time constant by combining this estimate with the value obtained at the last voltage measurement point (v S ) near c selection combination to determine. S voltage measurement data points (v i ) 1≤i≤S One or more voltage measurement data points in can be selected based on their corresponding switching time from using the integration method to using the exponential regression method within the demagnetization process cycle (e.g., corresponding to the transition time between a first time period showing saturation and a second time period without saturation).

[0205] For example, in some embodiments, the second flux estimate component can be obtained by dividing the estimate of the rotor time constant by With the last voltage measurement point (v S ) is combined to determine, for example, based on the product Because the last voltage measurement point (v S ) in some embodiments may correspond to a switching time from using an integral method to using an exponential regression method within a demagnetization process cycle (eg, corresponding to a transition time between a first time period showing saturation and a second time period without saturation).

[0206] Therefore, in one or more embodiments, the method switching time (t st), which corresponds to the switching time from using the integral method to using the exponential regression method within the demagnetization process cycle (e.g., corresponding to the transition time between a first time period showing saturation of the application of the integral and a second time period showing non-saturation of the application of the exponential regression). In some embodiments, the method switching time (t st ) may correspond to SΔt, where S is the number of voltage measurement data points collected during a voltage measurement period and Δt is the sampling period used to collect the voltage measurement data points).

[0207] In one or more embodiments, the method switching time (t st ) may be a parameter of the proposed method configured (determined) based on a preliminary estimate of the rotor time constant. Such a preliminary estimate of the rotor time constant of the induction motor may be provided by the manufacturer of the motor in the data sheet of the motor. Thus, the voltage measurement during the voltage measurement period includes S voltage measurement data points (v i ) 1≤i≤s In an embodiment, the voltage measurement data points (v) to be acquired during the core demagnetization of the motor may be selected based on a preliminary estimate of the rotor time constant, such as based on a multiple of the preliminary estimate of the rotor time constant (e.g., 2 or 3 times the preliminary estimate of the rotor time constant). i ) 1≤i≤S The number S.

[0208] In some embodiments, the integration method can be applied from the start of the demagnetization process to the method switching time (t st ) measured voltage, and the first flux estimate can be determined based on the results of the integration method, and the exponential regression method can be used to determine the time corresponding to the switching time from the method (t st ) to the second magnetic flux estimation component of the core demagnetization from the end of demagnetization.

[0209] In one or more embodiments, the voltage measurement data points may be based on one or more voltage measurement data points of the plurality of voltage measurement data points (eg, based on the last voltage measurement point v S ), or based on S voltage measurement data points (v i ) 1≤i≤S The average voltage value of multiple voltage measurement data points averaged To determine the second magnetic flux estimation component (e.g., at the last voltage measurement point (v S ) of S voltage measurement data points (v i ) 1≤i≤S neighborhood).

[0210] In some embodiments, each of the plurality of voltage measurement data points selected for determining the average voltage value may be included in the set {v S+k} -2K≤k≤0In some embodiments, it is possible to determine the voltage measurement data points (v i ) 1≤i≤s The average voltage value of multiple voltage measurement data points averaged in For example, according to the following formula:

[0211]

[0212] In some embodiments, the average voltage value can provide a method switching time (t st )’s average voltage value.

[0213] In one or more embodiments, the voltage measurement at the motor terminals in a stationary state may be performed during a preconfigured voltage measurement period and may continue for a period of time after the voltage measurement period expires. For example, after the preconfigured voltage measurement period ends, voltage measurement data points may still be acquired. In some embodiments, the voltage measurement data points acquired after the preconfigured voltage measurement period ends may be used to calculate the method switching time (t st ), for example according to the following formula:

[0214]

[0215] The use of an average value advantageously allows rejection of high frequency noise measurements and provides a time interval corresponding to the method switching time (t st ) is a better representative value of the voltage at the moment of the demagnetization process.

[0216] In one or more embodiments, the second flux estimate component can be obtained by dividing the estimated rotor time constant by Average voltage value with method switching time Combined to determine, for example, based on the product,

[0217] Therefore, in some embodiments, an exponential regression method can provide an estimate of the rotor time constant And this estimate may be combined with the voltage value corresponding to the method switching time, for example, in some embodiments, the average voltage value corresponding to the method switching time.

[0218] In one or more embodiments, an estimate of the magnetic flux of the motor core after magnetization (eg, generated by DC injection) may be determined based on the following formula:

[0219]

[0220] in is the estimated value of the time constant of the motor rotor, and S is the voltage measurement data point (v i ) 1≤i≤S The number of is the average voltage value during the switching time based on the S·Δt configuration method. For example, the average voltage value It can be determined based on the following formula:

[0221]

[0222] Or, depending on the embodiment, based on the following formula:

[0223]

[0224] Therefore, advantageously, in order to benefit from each of the advantages of the integral method and the exponential regression method, the proposed scheme advantageously uses the integral method at the beginning of the demagnetization process of the magnetic core, where magnetic saturation is most likely to occur, and then, after a preconfigured time interval, switches to the exponential regression method to take into account the residual magnetic flux of the demagnetization process. This hybrid provides many benefits. For example, errors are less likely to accumulate and become non-negligible because the use time of the integral method is not as long as the entire demagnetization process. In addition, observing that the saturation effect only affects multiples of the rotor time constant (e.g., the previous one to two times), the integral method will take into account this effect, and the remaining part of the voltage signal can be more reliably considered to be exponentially declining, which is then more efficiently processed by the exponential regression method. Finally, because the flux can be easily calculated mathematically once the parameters of the exponential curve are accurately estimated, the exponential regression advantageously allows the flux to be estimated before the measured voltage completely decays, which makes the proposed method time-saving.

[0225] A preliminary estimate of the rotor time constant can advantageously be used to parameterize the switching instant between the two methods.

[0226] In one or more embodiments, the rotor resistance (R r ) can be estimated based on the motor’s magnetic induction component (L0) and the rotor time constant to be determined by an estimate.

[0227] Note that Figure 2 The magnetic induction component L and rotor resistance R of the model circuit r The time constant of the inductor-resistor parallel circuit can be expressed as In some embodiments, the rotor resistance R r The estimated value of the motor magnetic induction component (L0) and the rotor time constant can be used to calculate the The estimated ratio For example, in some embodiments, the rotor resistance R r for

[0228] Figure 8 An exemplary motor drive 100 is shown that is configured to utilize features according to an embodiment of the present invention.

[0229] The motor drive device 100 may include a control engine 101, a motor drive engine 102, a motor interface engine 103, a memory 105, and a power source (e.g., a battery, a plug-in power source, etc.) (not shown in the figure). The motor drive device may be configured with a data communication interface (not shown in the figure), the interface configuration is used to connect the device to the induction motor (through one or more motor terminals of the motor) to drive the induction motor through the data communication interface (not shown in the figure), and / or is configured with an electrical signal interface for electrically connecting the device 103 to the induction motor (through one or more motor terminals of the motor).

[0230] exist Figure 8 In the illustrated architecture, all motor drive engines 102 , motor interface engines 103 , and memories 104 are operably coupled to each other via a control engine 101 .

[0231] In one or more embodiments, the motor drive engine 102 is configured to perform various aspects of embodiments of the proposed method for configuring a motor drive as described herein. For example, in some embodiments, the motor interface engine 103 can be configured to determine an estimate of a magnetic induction component of the motor operating in a linear manner based on N voltage measurements at the motor terminals of the induction motor performed during a core demagnetization of the induction motor, determine an estimate of a time constant of a rotor of the motor operating in a linear manner based on one of the N voltage measurements, and determine an estimate of a rotor resistance of the motor based on an estimate of the magnetic induction component of the motor and the rotor time constant.

[0232] In one or more embodiments, the motor interface engine 103 is configured to manage one or more of a data communication interface and an electrical signal interface with the motor when the motor drive device 100 is connected to the motor to be driven. For example, in some embodiments, the motor interface engine 103 may be configured to perform N measurements of the voltage at the motor terminals of a stationary motor during the demagnetization of the magnetic core of the motor.

[0233] The control engine 101 includes a processor, which can be any suitable microprocessor, microcontroller, field programmable gate array (FPGA), application specific integrated circuit (ASIC), digital signal processing chip and / or state machine or combination thereof. According to various embodiments, one or more computers can be configured as a multi-processor computer with multiple processors for providing parallel computing. The control engine 101 can also include a computer storage medium, such as but not limited to a memory 104, or can communicate with a computer storage medium, which can store computer program instructions or software codes, which, when executed by the processor, cause the processor to perform the elements described herein. In addition, the memory 104 can be any type of data storage computer storage medium, which can store a data structure representing a computer network to which the motor drive device 100 belongs, is connected to the control engine 101, and can operate with the motor interface engine 103 and the motor drive engine 102 to facilitate management and processing of data stored in association therewith.

[0234] In an embodiment of the subject disclosure, the motor drive apparatus 100 is configured to perform the methods described herein.

[0235] It should be understood that reference Figure 8 The motor drive device 1 shown and described is provided only as an example. Many other architectures, operating environments, and configurations are possible. Other embodiments of the node may include fewer or more components and may be combined with the relevant Figure 8 The motor drive device components shown may be used to describe some or all of the functions. Therefore, although the control engine 101, the motor drive engine 102, the motor interface engine 103, and the memory 104 are illustrated as part of the motor drive device 100, there is no limitation on the location and control of the components 102-104. In particular, in other embodiments, the components 102-104 may be part of different entities or computing systems.

[0236] Depending on the embodiment, the device 100 can be implemented in software as described above, or in hardware such as an application-specific integrated circuit (ASIC), or in the form of a combination of hardware and software, such as a software program intended to be loaded and executed on an FPGA (field programmable gate array) type component.

[0237] Fig. 9 The performance of the proposed method is shown. Fig. 9 The flux-current curve of the actual motor and the flux-current curve estimated using the proposed scheme are shown. Fig. 9 As shown, using a real test bench, the proposed method gives a magnetization curve that is very close to the real curve. Fig. 9In the figure, the horizontal line represents the nominal flux that needs to be applied when controlling the motor. The "Ida" symbol (which represents the nominal flux current of the motor) refers to the magnetizing current that produces the nominal flux. In the performance test shown in the figure, 5 DC injections were performed and 5 corresponding flow values ​​were estimated. The saturation model was then fitted at these 5 points and the resulting magnetization curve is shown in bold. Another curve shows the true magnetization curve.

[0238] A single DC injection is used to estimate the rotor time constant τ0, and 5 DC injections (4 additional DC injections) are used to estimate the inductive component L0 in linear mode, thereby estimating the rotor resistance.

[0239] The results are reported in Table 1 below, from which we can see the low error values ​​of the proposed method, which provides a performance level comparable to rotary tuning, but with much fewer limitations, since the proposed method does not require mechanical decoupling of the motor.

[0240] Table 1:

[0241] Motor power Reference rotor resistance Estimated rotor resistance error 0.7500kW 4682.mO 4599.mO -1.77％ 7.500kW 267.3mO 292.6mO 9.49％ 11.00kW 175.1mO 179.7mO 2.59％ 15.00kW 157.9mO 168.4mO 6.68％ 22.00kW 60.73mO 63.29mO 4.22％ 90.00kW 9.507mO 9.244mO -2.77％ 250.0kW 2.746mO 3.007mO 9.53％

[0242] While the present invention has been described with reference to preferred embodiments, those skilled in the art will readily appreciate that various changes and / or modifications may be made to the present invention without departing from the spirit or scope of the invention as defined by the appended claims.

[0243] Although the present invention has been disclosed in the context of certain preferred embodiments, it should be understood that certain advantages, features and aspects of the systems, devices and methods can be implemented in various other embodiments. In addition, it is expected that the various aspects and features described herein can be implemented separately, combined together or replaced with each other, and various combinations and sub-combinations of features and aspects can be made and still fall within the scope of the present invention. In addition, the above-mentioned systems and devices do not need to include all modules and functions described in the preferred embodiments.

[0244] The information and signals described herein may be represented using any of a variety of techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0245] Depending on the embodiment, certain actions, events, or functions of any method described herein may be performed in a different order, may be added, combined, or omitted together (e.g., not all described actions or events are necessary for the practice of the method). In addition, in some embodiments, actions or events may be performed simultaneously, rather than sequentially.

Claims

1. A method of configuring a motor drive for driving an induction motor, the motor comprising a rotor and a magnetic core comprising a magnetic induction component, the method comprising: performing N measurements of the voltage at the motor terminals of the stationary motor during demagnetization of the magnetic core of the motor; determining an estimate of a magnetic induction component of the motor operating in a linear manner based on the N voltage measurements; determining an estimate of a time constant of a rotor of a motor operating in a linear manner based on one of the N voltage measurements; An estimate of the rotor resistance of the electric machine is determined based on an estimate of a magnetic induction component of the electric machine and a time constant of the rotor.

2. The method according to claim 1, further comprising: A motor drive is configured based on an estimate of the rotor resistance of the motor.

3. The method according to any one of the preceding claims, further comprising: Prior to each voltage measurement, a respective value of a direct current DC current is injected into the stationary electric machine for a respective duration of magnetization of a core of the electric machine, wherein the respective value of the DC current is one of a set of respective values ​​having different levels of DC current.

4. The method according to any one of the preceding claims, further comprising: For each voltage measurement, an estimate of the magnetic flux in the magnetically inductive component of the electric machine is determined based on the voltage measurement.

5. The method according to any one of the preceding claims, further comprising: N pairs of current and magnetic flux values ​​are determined based on N voltage measurements performed after injecting respective DC current values ​​into the motor at rest for respective time periods.

6. The method according to claim 5, further comprising: One or more parameters of a magnetic saturation model of a magnetically inductive component of the electric machine are determined based on the N pairs of current and magnetic flux values.

7. The method according to claim 6, further comprising: A magnetic saturation curve corresponding to a magnetic saturation model is determined, the magnetic saturation model fitting N points corresponding to N pairs of current and magnetic flux values, respectively.

8. The method of claim 7, wherein the magnetic saturation curve is determined using a linear regression algorithm.

9. A method according to any one of the preceding claims, wherein an estimate of the time constant of the rotor is determined based on one of the N voltage measurements using an exponential regression algorithm.

10. A method according to any one of the preceding claims, wherein the electric machine is an asynchronous induction machine.

11. The method according to any one of the preceding claims, wherein the one or more voltage measurements comprise S voltage measurement data points (v i ) 1≤i≤S , S is a non-zero natural number.

12. An apparatus comprising a processor, a memory operatively coupled to the processor, and an interface for coupling to an induction motor driven by the apparatus, wherein the apparatus is configured to perform the method according to any one of claims 1 to 11.

13. A computer program product comprising a computer program code tangibly embodied in a computer readable medium, the computer program code comprising instructions which, when provided to a computer system and executed, cause the computer to perform the method according to any one of claims 1 to 12.

14. A data set, for example compressed or encoded, representing a computer program product according to claim 13.

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