Motor high-precision torque estimation method based on detection coil

Abstract

The invention relates to a motor high-precision torque estimation method based on a detection coil. The invention relates to the technical field of motor driving control, and the method comprises the steps: installing a certain number of detection coils in a stator groove below a main flux linkage of a motor winding, achieving the detection of the main flux of the winding, and obtaining the flux linkage information of the winding; after the counter electromotive force of the detection coil is accurately obtained through the sampling circuit, the winding counter electromotive force information is obtained through conversion according to the winding coefficient ratio kcw between the detection coil and the winding. The torque of the detection coil is estimated, the back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil, coordinate transformation and integration are carried out to obtain psi alpha and psi beta, and the estimated value of the torque is obtained; a motor twin-trawling experiment platform is built, and a test motor operates in a torque mode so as to control the torque of the system. The problems that a torque estimation method is complex in structure and low in estimation precision are well solved.

Description

Technical Field

[0001] The invention relates to the technical field of motor drive control, and is a method for estimating motor torque with high precision based on a detection coil. Background Art

[0002] As the core device of energy conversion and control, the motor is widely used in every field of modern society. The interior permanent magnet synchronous motor (IPMSM) is widely used in industrial fields such as electric vehicles, rail transportation and robots due to its high efficiency, high power density and excellent dynamic response characteristics. In these fields, the motor usually works in torque mode as a power device, and high-precision torque feedback is the key basis for achieving precise torque control. However, due to the constraints of installation and maintenance costs, torque sensors are often not installed in the transmission system, and direct torque measurement becomes more difficult. Therefore, the importance and urgency of accurately estimating the torque of the motor are self-evident. At present, many methods have been proposed for estimating the torque of the motor. Among them, the parameter identification method usually requires the injection of high-frequency signals to achieve estimation, and its operation will affect the control performance and has high computational complexity. Although the voltage integration method is simple in principle, the accuracy of flux observation is easily affected by the initial value and drift of the integral, and the torque estimation accuracy is affected by the inverter voltage drop and system loss. Although the analytical calculation method is widely used due to its simple operation, it relies on a lookup table to obtain the flux or inductance parameters, which not only requires a large number of preliminary experiments, significantly increasing the software development cycle and cost, but the torque estimation accuracy is also easily affected by the motor temperature. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a high-precision motor torque estimation method based on a detection coil. In this method, the detection coil is installed inside the motor stator to directly obtain the back-EMF information of the winding, which makes it in principle unaffected by the motor parameters, motor state and system losses, greatly improves the accuracy and robustness of the motor torque estimation, and better solves the problem of complex structure and low estimation accuracy of the torque estimation method.

[0004] The present invention provides the following technical solutions:

[0005] A method for estimating the high-precision torque of a motor based on a detection coil, the method comprising the following steps:

[0006] Step 1: Install a certain number of detection coils in the stator slots below the main magnetic flux of the motor winding to detect the main magnetic flux of the winding and obtain the winding magnetic flux information;

[0007] Step 2: After accurately obtaining the back electromotive force of the detection coil through the sampling circuit, the winding coefficient ratio k between the detection coil and the winding is used cwTransform to obtain the winding back electromotive force information;

[0008] Step 3: Estimate the torque of the detection coil. The back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil. ψ can be obtained by coordinate transformation and integration. α and ψ β , obtain the estimated value of torque;

[0009] Step 4: Build a motor-to-motor drag experiment platform to test the motor running in torque mode to control the torque of the system.

[0010] Preferably, the step 1 is specifically:

[0011] First determine the number of poles and slots of the motor, then determine the minimum distribution unit of the main winding, and install the detection coil in the slot corresponding to the minimum distribution unit of each phase winding;

[0012] When the motor is running, the magnetic flux in the detection coil changes with the main magnetic flux of the winding, and the back electromotive force of the main magnetic flux is expressed by the following formula:

[0013]

[0014] Among them, e sc is the back electromotive force of the detection coil, N t,c is the number of turns of the detection coil, φ sc is the air gap flux of the detection coil.

[0015] Preferably, the step 2 is specifically:

[0016] k cw The size of is related to the distribution factor and pitch factor of the detection coil and winding respectively. The pitch factor is expressed by the following formula:

[0017]

[0018] Among them, k p is the pitch factor, y is the pitch, and τ is the pole pitch;

[0019] The winding distribution factor is expressed by the following formula:

[0020]

[0021] Among them, k d is the distribution factor, q is the number of slots per pole per phase, and α is the slot pitch angle;

[0022] The number of turns of the winding and coil and the number of ways in series connection finally give the ratio of the winding coefficient between the detection coil and the winding:

[0023]

[0024] Among them, k cw is the ratio of the winding coefficient between the detection coil and the winding, w is the subscript representing the winding coefficient, c is the subscript representing the coil coefficient, N t is the number of turns, N s is the number of series branches;

[0025] The k is determined based on the motor pole slot matching and the layout design of the detection coil. cw After that, the back electromotive force e of the detection coil sc Get the back EMF of the motor winding:

[0026] E ph =k cw e sc

[0027] Among them, E ph is the opposite potential of the stator winding.

[0028] Preferably, the step 3 is specifically:

[0029] When integrating the back EMF, a second-order generalized integrator is used to integrate the back EMF, and the transfer function is expressed by the following formula:

[0030]

[0031] Among them, ω1 represents the fundamental frequency of the integrated signal, and k is the filtering parameter of SOGI.

[0032] Preferably, the step 4 is specifically:

[0033] The speed of the system is controlled at 500r / min through the load motor, and the actual waveform of the back EMF of the A-phase detection coil and winding is obtained. The kcw can be calculated by Fourier analysis of the back EMF of the detection coil and the test motor winding and compared with the theoretical calculation and simulation results.

[0034] Preferably, the speed of the test motor is controlled to run at a rated speed of 3000r / min through a load motor, and the output torque of the tested motor under different load conditions is tested; based on the comparison between the torque estimation value of the detection coil and the measurement value of the torque sensor.

[0035] Preferably, according to the generation of motor torque, the electromagnetic torque T of the three-phase permanent magnet synchronous motor e It is expressed as:

[0036] T e =1.5pψ g ×i s

[0037] Where p is the number of motor pole pairs, ψ g represents the air gap flux vector, is represents the stator current vector;

[0038] The electromagnetic torque is rewritten as:

[0039] T e =1.5p(ψ α i β -ψ β i α )

[0040] Among them, ψ α and ψ β is the magnetic flux linkage of the αβ axis.

[0041] A high-precision motor torque estimation system based on a detection coil, the system comprising:

[0042] An information acquisition module, wherein a certain number of detection coils are installed in stator slots below the main magnetic flux of the motor winding to detect the main magnetic flux of the winding and acquire the winding magnetic flux information;

[0043] The sampling module, after accurately obtaining the back electromotive force of the detection coil through the sampling circuit, uses the winding coefficient ratio k between the detection coil and the winding cw Transform to obtain the winding back electromotive force information;

[0044] The torque estimation module estimates the torque of the detection coil. The back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil. The coordinate transformation and integration can be used to obtain ψ α and ψ β , obtain the estimated value of torque;

[0045] The experimental module, the implementation module builds a motor drag experimental platform to test the motor running in the torque mode to control the torque of the system.

[0046] A computer-readable storage medium stores a computer program, which is executed by a processor to implement a high-precision motor torque estimation method based on a detection coil.

[0047] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements a high-precision motor torque estimation method based on a detection coil when executing the computer program.

[0048] The present invention has the following beneficial effects:

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] The invention directly obtains the back-EMF signal of the winding by arranging a detection coil inside the motor, and then obtains an accurate motor torque estimation value through a sampling circuit and subsequent calculation processing. The invention provides a new high-precision torque estimation method, and the simulation and experimental results verify the feasibility and effectiveness of the proposed method.

[0051] Subsequently, the speed of the test motor was controlled to run at the rated speed of 3000r / min through the load motor. The torque estimation value obtained by the output torque detection coil method of the tested motor under different load conditions was highly close to the actual measured value, which greatly improved the accuracy of motor torque estimation. The maximum estimation error did not exceed 2% of the actual torque.

[0052] The detection coil of the present invention is installed inside the motor stator to directly obtain the back-electromotive force information of the winding, which makes it unaffected by motor parameters, motor status and system losses in principle, greatly improves the accuracy and robustness of motor torque estimation, and better solves the problem of complex structure and low estimation accuracy of torque estimation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 Shown is a flow chart of the arrangement of the detection coil of the present invention;

[0055] Figure 2 Shown is a schematic diagram of the arrangement of the detection coils of the 8-pole 48-slot motor of the present invention;

[0056] Figure 3 Shown is a block diagram of the torque estimation method of the present invention;

[0057] Figure 4 Shown is the SOGI integrator of the present invention;

[0058] Figure 5 The display is a comparison of the back EMF waveforms of the A-phase detection coil and the winding at 500 r / min of the present invention;

[0059] Figure 6 The figure shows the comparison between the torque estimation value based on the detection coil method and the actual torque value under different working conditions of the present invention. DETAILED DESCRIPTION

[0060] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0062] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0064] The present invention is described in detail below in conjunction with specific embodiments. Specific embodiment one:

[0066] according to Figures 1 to 6 As shown, the specific optimization technical solution adopted by the present invention to solve the above technical problems is: the present invention relates to a high-precision motor torque estimation method based on detection coils.

[0067] A method for estimating the high-precision torque of a motor based on a detection coil, the method comprising the following steps:

[0068] Step 1: Install a certain number of detection coils in the stator slots below the main magnetic flux of the motor winding to detect the main magnetic flux of the winding and obtain the winding magnetic flux information;

[0069] Step 2: After accurately obtaining the back electromotive force of the detection coil through the sampling circuit, the winding coefficient ratio k between the detection coil and the winding is used cw Transform to obtain the winding back electromotive force information;

[0070] Step 3: Estimate the torque of the detection coil. The back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil. ψ can be obtained by coordinate transformation and integration. α and ψ β , obtain the estimated value of torque;

[0071] Step 4: Build a motor-to-motor drag experiment platform to test the motor running in torque mode to control the torque of the system.

[0072] The detection coil of the present invention is installed inside the motor stator to directly obtain the back-electromotive force information of the winding, which makes it unaffected by motor parameters, motor status and system losses in principle, greatly improves the accuracy and robustness of motor torque estimation, and better solves the problem of complex structure and low estimation accuracy of torque estimation method.

[0073] The invention directly obtains the back-EMF signal of the winding by arranging a detection coil inside the motor, and then obtains an accurate motor torque estimation value through a sampling circuit and subsequent calculation processing. The invention provides a new high-precision torque estimation method, and the simulation and experimental results verify the feasibility and effectiveness of the proposed method. Specific embodiment 2:

[0075] The difference between the second embodiment of the present application and the first embodiment is that:

[0076] The step 1 is specifically as follows:

[0077] First determine the number of poles and slots of the motor, then determine the minimum distribution unit of the main winding, and install the detection coil in the slot corresponding to the minimum distribution unit of each phase winding;

[0078] When the motor is running, the magnetic flux in the detection coil changes with the main magnetic flux of the winding, and the back electromotive force of the main magnetic flux is expressed by the following formula:

[0079]

[0080] Among them, e sc is the back electromotive force of the detection coil, N t,c is the number of turns of the detection coil, φ sc is the air gap flux of the detection coil. Specific embodiment three:

[0082] The difference between the third embodiment of the present application and the second embodiment is that:

[0083] The step 2 is specifically as follows:

[0084] k cw The size of is related to the distribution factor and pitch factor of the detection coil and winding respectively. The pitch factor is expressed by the following formula:

[0085]

[0086] Among them, k p is the pitch factor, y is the pitch, and τ is the pole pitch;

[0087] The winding distribution factor is expressed by the following formula:

[0088]

[0089] Among them, k d is the distribution factor, q is the number of slots per pole per phase, and α is the slot pitch angle;

[0090] The number of turns of the winding and coil and the number of ways in series connection finally give the ratio of the winding coefficient between the detection coil and the winding:

[0091]

[0092] Among them, k cw is the ratio of the winding coefficient between the detection coil and the winding, w is the subscript representing the winding coefficient, c is the subscript representing the coil coefficient, N t is the number of turns, N s is the number of series branches;

[0093] The k is determined based on the motor pole slot matching and the layout design of the detection coil. cw After that, the back electromotive force e of the detection coil sc Get the back EMF of the motor winding:

[0094] E ph =k cw e sc

[0095] Among them, E ph is the opposite potential of the stator winding. Specific embodiment four:

[0097] The difference between the fourth embodiment of the present application and the third embodiment is that:

[0098] The step 3 is specifically as follows:

[0099] When integrating the back EMF, a second-order generalized integrator is used to integrate the back EMF, and the transfer function is expressed by the following formula:

[0100]

[0101] Among them, ω1 represents the fundamental frequency of the integrated signal, and k is the filtering parameter of SOGI. Specific embodiment five:

[0103] The difference between the fifth embodiment of the present invention and the fourth embodiment is that:

[0104] The step 4 is specifically as follows:

[0105] The speed of the system is controlled at 500r / min through the load motor, and the actual waveform of the back EMF of the A-phase detection coil and winding is obtained. The kcw can be calculated by Fourier analysis of the back EMF of the detection coil and the test motor winding and compared with the theoretical calculation and simulation results. Specific embodiment six:

[0107] The difference between the sixth embodiment of the present invention and the fifth embodiment is that:

[0108] The speed of the test motor is controlled at the rated speed of 3000r / min through the load motor, and the output torque of the motor under different load conditions is tested; the torque estimation value based on the detection coil is compared with the measured value of the torque sensor. Specific embodiment seven:

[0110] The difference between the seventh embodiment of the present invention and the sixth embodiment is that:

[0111] According to the generation of motor torque, the electromagnetic torque T of the three-phase permanent magnet synchronous motor e It is expressed as:

[0112] T e =1.5pψ g ×i s

[0113] Where p is the number of motor pole pairs, ψ g represents the air gap flux vector, i s represents the stator current vector;

[0114] The electromagnetic torque is rewritten as:

[0115] T e =1.5p(ψ α i β -ψ β i α )

[0116] Among them, ψ α and ψ β is the magnetic flux linkage of the αβ axis. Specific embodiment eight:

[0118] The difference between the eighth embodiment of the present invention and the seventh embodiment is that:

[0119] The present invention provides a motor high-precision torque estimation system based on a detection coil, the system comprising:

[0120] An information acquisition module, wherein a certain number of detection coils are installed in stator slots below the main magnetic flux of the motor winding to detect the main magnetic flux of the winding and acquire the winding magnetic flux information;

[0121] The sampling module, after accurately obtaining the back electromotive force of the detection coil through the sampling circuit, uses the winding coefficient ratio k between the detection coil and the winding cw Transform to obtain the winding back electromotive force information;

[0122] The torque estimation module estimates the torque of the detection coil. The back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil. The coordinate transformation and integration can be used to obtain ψ α and ψ β , obtain the estimated value of torque;

[0123] The experimental module, the implementation module builds a motor drag experimental platform to test the motor running in the torque mode to control the torque of the system.

[0124] The detection coil of the present invention is installed inside the motor stator to directly obtain the back-electromotive force information of the winding, which makes it unaffected by motor parameters, motor status and system losses in principle, greatly improves the accuracy and robustness of motor torque estimation, and better solves the problem of complex structure and low estimation accuracy of torque estimation method. Specific embodiment nine:

[0126] The difference between the ninth embodiment of the present invention and the eighth embodiment is that:

[0127] The present invention provides a computer-readable storage medium on which a computer program is stored. The program is executed by a processor to implement a method for estimating the high-precision torque of a motor based on a detection coil.

[0128] The method comprises the following steps:

[0129] Step 1: Install a certain number of detection coils in the stator slots below the main magnetic flux of the motor winding to detect the main magnetic flux of the winding and obtain the winding magnetic flux information;

[0130] Step 2: After accurately obtaining the back electromotive force of the detection coil through the sampling circuit, the winding coefficient ratio k between the detection coil and the winding is used cw Transform to obtain the winding back electromotive force information;

[0131] Step 3: Estimate the torque of the detection coil. The back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil. ψ can be obtained by coordinate transformation and integration. α and ψ β , obtain the estimated value of torque;

[0132] Step 4: Build a motor-to-motor drag experiment platform to test the motor running in torque mode to control the torque of the system. Specific embodiment ten:

[0134] The difference between the tenth embodiment of the present invention and the ninth embodiment is that:

[0135] The present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements a high-precision motor torque estimation method based on a detection coil when executing the computer program.

[0136] The method comprises the following steps:

[0137] Step 1: Install a certain number of detection coils in the stator slots below the main magnetic flux of the motor winding to detect the main magnetic flux of the winding and obtain the winding magnetic flux information;

[0138] Step 2: After accurately obtaining the back electromotive force of the detection coil through the sampling circuit, the winding coefficient ratio k between the detection coil and the winding is used cw Transform to obtain the winding back electromotive force information;

[0139] Step 3: Estimate the torque of the detection coil. The back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil. ψ can be obtained by coordinate transformation and integration. α and ψ β , obtain the estimated value of torque;

[0140] Step 4: Build a motor-to-motor drag experiment platform to test the motor running in torque mode to control the torque of the system. Specific embodiment eleven:

[0142] The difference between the eleventh embodiment of the present invention and the tenth embodiment is that:

[0143] The present invention proposes a high-precision torque estimation method based on a detection coil (SC). In this method, the detection coil is installed inside the motor stator to directly obtain the back-EMF information of the winding, which makes it unaffected by the motor parameters, motor state and system loss in principle, greatly improves the accuracy and robustness of the motor torque estimation, and better solves the problem of complex structure and low estimation accuracy of the torque estimation method.

[0144] Basic principles of torque estimation

[0145] According to the principle of motor torque generation, taking a three-phase permanent magnet synchronous motor as an example, its electromagnetic torque T e It can be expressed as:

[0146] T e =1.5pψ g×i s (1)

[0147] Where p is the number of motor pole pairs, ψ g represents the air gap flux vector, i s Represents the stator current vector.

[0148] According to formula (1), the electromagnetic torque can be rewritten as:

[0149] T e =1.5p(ψ α i β -ψ β i α ) (2)

[0150] In the formula, ψ α and ψ β is the magnetic flux linkage of the αβ axis.

[0151] Step 1: Arrangement of detection coil

[0152] In order to obtain accurate winding flux information, a certain number of detection coils need to be installed in the stator slots below the main flux of the motor winding to detect the main magnetic flux of the winding. The basic principle of its layout is that the magnetic field information induced by the detection coil can fully reproduce all the characteristics of the winding magnetic field. The detection coil layout process is as follows: Figure 1 As shown, taking 8 poles and 48 slots as an example, the schematic diagram of its arrangement is as follows Figure 2 When the motor is running, the magnetic flux in the detection coil changes with the main magnetic flux of the winding, and the back electromotive force of the main magnetic flux can be expressed as:

[0153]

[0154] In the formula, e sc is the back electromotive force of the detection coil, N t,c is the number of turns of the detection coil, φ sc is the air gap flux of the detection coil.

[0155] Step 2: Calculation of winding back EMF

[0156] After the back electromotive force of the detection coil is accurately obtained through the sampling circuit, the winding coefficient ratio k between the detection coil and the winding can be used to calculate the back electromotive force of the detection coil. cw Transform to obtain the winding back EMF information, k cw The size of is related to the distribution factor and pitch factor of the detection coil and winding respectively.

[0157] The pitch factor is:

[0158]

[0159] In the formula, k pis the pitch factor, y is the pitch, and τ is the pole pitch.

[0160] The winding distribution factor is:

[0161]

[0162] In the formula, k d is the distribution factor, q is the number of slots per pole per phase, and α is the slot pitch angle.

[0163] In addition, considering the number of turns and series connections of the winding and coil, the ratio of the winding coefficient between the detection coil and the winding can be obtained as follows:

[0164]

[0165] In the formula, k cw is the ratio of the winding coefficient between the detection coil and the winding, w is the subscript indicating the winding coefficient, c is the subscript indicating the coil coefficient, N t is the number of turns, N s is the number of series branches.

[0166] The k is determined based on the motor pole slot matching and the layout design of the detection coil. cw After that, the back electromotive force e of the detection coil can be used sc Obtain the back EMF of the motor winding.

[0167] E ph =k cw e sc (7)

[0168] In the formula, E ph is the opposite potential of the stator winding.

[0169] Since the sampling circuit usually has an infinite equivalent input impedance, the detection coil can be considered to be in an open circuit. Therefore, the winding back EMF obtained by the detection coil is not affected by the coil and winding impedance, and theoretically eliminates the influence of motor iron loss and permanent magnet loss.

[0170] Step 3: Estimation of torque

[0171] Taking a three-phase permanent magnet synchronous motor as an example, the torque estimation process based on the detection coil is as follows: Figure 3 The back electromotive force of the three-phase winding is obtained indirectly by sampling the detection coil, and then the coordinate transformation and integration are performed to obtain ψ α and ψ β Finally, according to formula (2), the estimated value of the torque can be obtained.

[0172] When integrating the back EMF, the integrator cannot be directly integrated due to the DC bias problem. Therefore, a second-order generalized integrator (SOGI) is used to integrate the back EMF. The structure of SOGI is as follows: Figure 4 As shown, its transfer function can be expressed as:

[0173]

[0174] Where ω1 represents the fundamental frequency of the integrated signal, and k is the filtering parameter of SOGI.

[0175] Step 4: Experimental verification

[0176] The present invention builds a motor dragging experimental platform, in which the load motor runs in speed mode to control the speed of the system, and the test motor runs in torque mode to control the torque of the system. At the same time, the controller uses TI's TMS320F28377D chip to execute the control algorithm, and uses an 8-channel analog-to-digital converter AD7606B to sample the voltage of the three-phase detection coil, and its sampling voltage range is -10V to 10V. In addition, the speed and torque of the test motor are accurately measured by HBM's T40B sensor, and then displayed and stored by Yokogawa power analyzer WT5000.

[0177] First, the system speed is controlled at 500r / min through the load motor, and the following is obtained: Figure 5 The actual waveform of the back EMF of the A-phase detection coil and winding is shown in Figure 1. By Fourier analysis of the back EMF of the detection coil and the test motor winding, k can be calculated. cw It is 31.84, which is basically consistent with the theoretical calculation and simulation results.

[0178] Subsequently, the speed of the test motor is controlled to run at the rated speed of 3000r / min through the load motor, and the output torque of the tested motor under different load conditions is tested. Figure 6 The comparison between the torque estimation value based on the detection coil and the measurement value of the torque sensor is shown. The comparison results show that the torque estimation value obtained by the detection coil method is highly close to the actual measurement value, which greatly improves the accuracy of motor torque estimation, and its maximum estimation error does not exceed 2% of the actual torque.

[0179] In summary, the present invention directly obtains the back-EMF signal of the winding by arranging a detection coil inside the motor, and then obtains an accurate motor torque estimation value through a sampling circuit and subsequent calculation processing. The invention provides a new high-precision torque estimation method, and the simulation and experimental results verify the feasibility and effectiveness of the proposed method.

[0180] In the description of this specification, the description of reference terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction. In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

[0181] The above is only a preferred implementation of a method for estimating the motor torque with high precision based on a detection coil. The protection scope of a method for estimating the motor torque with high precision based on a detection coil is not limited to the above embodiments. All technical solutions under this idea belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, several improvements and changes without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for estimating the motor torque with high precision based on a detection coil, characterized in that: The method comprises the following steps: Step 1: Install a certain number of detection coils in the stator slots below the main magnetic flux of the motor winding to detect the main magnetic flux of the winding and obtain the winding magnetic flux information; Step 2: After accurately obtaining the back electromotive force of the detection coil through the sampling circuit, the winding coefficient ratio k between the detection coil and the winding is used cw Transform to obtain the winding back electromotive force information; Step 3: Estimate the torque of the detection coil. The back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil. ψ can be obtained by coordinate transformation and integration. α and ψ β , obtain the estimated value of torque; Step 4: Build a motor-to-motor drag experiment platform to test the motor running in torque mode to control the torque of the system.

2. The method according to claim 1, characterized in that: The step 1 is specifically as follows: First determine the number of poles and slots of the motor, then determine the minimum distribution unit of the main winding, and install the detection coil in the slot corresponding to the minimum distribution unit of each phase winding; When the motor is running, the magnetic flux in the detection coil follows the change of the main magnetic flux of the winding, and the back electromotive force of the main magnetic flux is expressed by the following formula: Among them, e sc is the back electromotive force of the detection coil, N t,c is the number of turns of the detection coil, φ sc is the air gap flux of the detection coil.

3. The method according to claim 2, characterized in that: The step 2 is specifically as follows: k cw The size of is related to the distribution factor and pitch factor of the detection coil and winding respectively. The pitch factor is expressed by the following formula: Among them, k p is the pitch factor, y is the pitch, and τ is the pole pitch; The winding distribution factor is expressed by the following formula: Among them, k d is the distribution factor, q is the number of slots per pole per phase, and α is the slot pitch angle; The number of turns of the winding and coil and the number of ways in series connection finally give the ratio of the winding coefficient between the detection coil and the winding: Among them, k cw is the ratio of the winding coefficient between the detection coil and the winding, w is the subscript indicating the winding coefficient, c is the subscript indicating the coil coefficient, N t is the number of turns, N s is the number of series branches; The k is determined based on the motor pole slot matching and the layout design of the detection coil. cw After that, the back electromotive force e of the detection coil sc Get the back EMF of the motor winding: E ph =k cw yes sc Among them, E ph is the opposite potential of the stator winding.

4. The method according to claim 1, characterized in that: The step 3 is specifically as follows: When integrating the back EMF, a second-order generalized integrator is used to integrate the back EMF, and the transfer function is expressed by the following formula: Among them, ω1 represents the fundamental frequency of the integrated signal, and k is the filtering parameter of SOGI.

5. The method according to claim 4, characterized in that: The step 4 is specifically as follows: The speed of the system is controlled at 500r / min through the load motor, and the actual waveform of the back EMF of the A-phase detection coil and winding is obtained. The kcw can be calculated by Fourier analysis of the back EMF of the detection coil and the test motor winding and compared with the theoretical calculation and simulation results.

6. The method according to claim 1, characterized in that: The speed of the test motor is controlled at the rated speed of 3000r / min through the load motor, and the output torque of the motor under different load conditions is tested; the torque estimation value based on the detection coil is compared with the measured value of the torque sensor.

7. The method according to claim 6, characterized in that: According to the generation of motor torque, the electromagnetic torque T of the three-phase permanent magnet synchronous motor e It is expressed as: T e =1.5pψ g ×i s Where p is the number of motor pole pairs, ψ g represents the air gap flux vector, i s represents the stator current vector; The electromagnetic torque is rewritten as: Among them, ψ α and ψ β is the magnetic flux linkage of the αβ axis.

8. A high-precision motor torque estimation system based on a detection coil, characterized in that: The system comprises: An information acquisition module, wherein a certain number of detection coils are installed in stator slots below the main magnetic flux of the motor winding to detect the main magnetic flux of the winding and acquire the winding magnetic flux information; The sampling module, after accurately obtaining the back electromotive force of the detection coil through the sampling circuit, uses the winding coefficient ratio k between the detection coil and the winding cw Transform to obtain the winding back electromotive force information; The torque estimation module estimates the torque of the detection coil. The back electromotive force of the three-phase winding is indirectly obtained by sampling the detection coil. The coordinate transformation and integration can be used to obtain ψ α and ψ β , obtain the estimated value of torque; The experimental module, the implementation module builds a motor drag experimental platform to test the motor running in the torque mode to control the torque of the system.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the method according to claims 1-7.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the method of claims 1-7 is implemented.

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