Stable control method, system and equipment of asynchronous motor and storage medium

Abstract

The invention provides a stability control method, system and device for an asynchronous motor and a storage medium, and is applied to the technical field of motor control, and the stability control method for the asynchronous motor comprises the steps: obtaining a synchronous current of the asynchronous motor in a synchronous rotating coordinate system and a flux linkage error value of the asynchronous motor, and determining a gain correction matrix based on the synchronous current; and obtaining a voltage error value based on the product of the gain correction matrix and the flux linkage error value, and feeding back the voltage error value to a rotor flux linkage observer of the asynchronous motor to control the asynchronous motor to operate stably. According to the technical scheme, the pole position of the asynchronous motor is adjusted through the gain matrix, so that the operation stability of the motor can be improved, and the purpose of accurately controlling the rotating speed of the motor can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of motor control technology, and in particular to a stable control method, system, device and storage medium for an asynchronous motor. Background Art

[0002] With the development of power electronics technology and AC motor transmission technology, variable speed transmission systems consisting of frequency converters and AC motors have been widely used in rail transportation, electric vehicles, mechanical processing, household appliances and other fields. AC motors, especially asynchronous motors (also known as induction motors), have become the most widely used transmission equipment in the field of variable speed transmission applications due to their low cost, high reliability and easy maintenance.

[0003] In the transmission system of asynchronous motors, common speed closed-loop control methods include: model reference adaptive method, full-order adaptive observer method, reduced-order observer method, extended Kalman filter method, sliding mode observer method, etc. However, when controlling the motor by the above methods, it is easy to cause the motor to run unstably at certain speeds or under certain working conditions. Summary of the invention

[0004] The main purpose of the present invention is to provide a stable control method, system, device and storage medium for an asynchronous motor, aiming to provide a stable control scheme for an asynchronous motor, adjusting the pole position of the asynchronous motor through a gain matrix to improve the stability of the motor operation.

[0005] To achieve the above object, the present invention provides a stable control method for an asynchronous motor, the stable control method for an asynchronous motor comprising:

[0006] Acquire a synchronous current of the asynchronous motor in a synchronous rotating coordinate system and a flux linkage error value of the asynchronous motor, and determine a gain correction matrix based on the synchronous current;

[0007] A voltage error value is obtained based on the product of the gain correction matrix and the flux error value, and the voltage error value is fed back to the rotor flux observer of the asynchronous motor to control the asynchronous motor to operate stably.

[0008] Optionally, the synchronous current includes: a direct-axis current and a quadrature-axis current, and the step of determining a gain correction matrix based on the synchronous current includes:

[0009] determining an initial two-dimensional matrix based on the direct-axis current and the quadrature-axis current;

[0010] Determine a sum of the square of the direct-axis current and the square of the quadrature-axis current, and obtain a matrix coefficient based on the inverse of the sum;

[0011] The matrix coefficients are multiplied by the initial two-dimensional matrix to obtain a gain correction matrix.

[0012] Optionally, the step of obtaining a voltage error value based on the product of the gain correction matrix and the flux error value comprises:

[0013] A voltage error value is obtained based on the product of a preset gain coefficient, the gain correction matrix and the flux error value.

[0014] Optionally, after the step of feeding back the voltage error value to the rotor flux observer of the asynchronous motor, the method further comprises:

[0015] Acquire a final flux estimation value of the asynchronous motor, wherein the final flux estimation value includes a direct-axis flux estimation value and a quadrature-axis flux estimation value;

[0016] Determine the slip frequency based on the direct-axis flux estimation value and the quadrature-axis current, and determine the stator frequency by proportionally integrating the quadrature-axis flux estimation value;

[0017] A speed estimate is obtained based on a difference between the stator frequency and the slip frequency.

[0018] Optionally, the step of obtaining the flux error value of the asynchronous motor includes:

[0019] Obtaining a flux linkage estimation value based on a synchronous voltage and a synchronous current of the asynchronous motor in a synchronous rotating coordinate system, and obtaining a flux linkage given value based on the synchronous current;

[0020] A flux error value is obtained based on a difference between the given flux value and the estimated flux value.

[0021] Optionally, the step of obtaining a flux estimation value based on the synchronous voltage and the synchronous current of the asynchronous motor in a synchronous rotating coordinate system, and obtaining a flux given value based on the synchronous current comprises:

[0022] Determining a flux setting value corresponding to the synchronous current based on a preset rotor flux setting relationship;

[0023] Determine a flux estimation value corresponding to both the synchronous current and the synchronous voltage based on a rotor flux observer of the asynchronous motor;

[0024] Optionally, the step of obtaining a flux estimation value based on the synchronous voltage and the synchronous current of the asynchronous motor in a synchronous rotating coordinate system, and obtaining a flux given value based on the synchronous current comprises:

[0025] Converting the synchronous voltage of the asynchronous motor in a synchronous rotating coordinate system into a stationary voltage in a stationary coordinate system, and converting the synchronous current into a stationary current in a stationary coordinate system;

[0026] A flux linkage estimation value is obtained based on the static voltage and the static current, and a flux linkage set value is obtained based on the static current.

[0027] To achieve the above object, the present invention further provides a stable control system for an asynchronous motor, the stable control system for the asynchronous motor further comprising:

[0028] A data acquisition module, used to acquire a synchronous current of the asynchronous motor and a flux error value of the asynchronous motor in a synchronous rotating coordinate system, and determine a gain correction matrix based on the synchronous current;

[0029] The gain correction feedback module is used to obtain a voltage error value based on the product of the gain correction matrix and the flux error value, and feed the voltage error value back to the rotor flux observer of the asynchronous motor to control the asynchronous motor to run stably.

[0030] To achieve the above-mentioned purpose, the present invention also provides a stable control device for an asynchronous motor, wherein the stable control device for an asynchronous motor comprises: a memory, a processor, and a stable control program for the asynchronous motor stored in the memory and executable on the processor, wherein the stable control program for the asynchronous motor implements the steps of the stable control method for the asynchronous motor as described above when executed by the processor.

[0031] To achieve the above objectives, the present invention further provides a storage medium, on which a stabilization control program for an asynchronous motor is stored. When the stabilization control program for an asynchronous motor is executed by a processor, the steps of the stabilization control method for an asynchronous motor as described above are implemented.

[0032] In an embodiment of the present invention, by acquiring the synchronous current of the asynchronous motor and the flux error value of the asynchronous motor in a synchronous rotating coordinate system, and determining a gain correction matrix based on the synchronous current, the flux error information of the motor during current operation and the gain information required to correct the stable operation of the motor are obtained; then, the voltage error value is obtained by multiplying the gain correction matrix and the flux error value, and the voltage error value is fed back to the rotor flux observer of the asynchronous motor, so that the pole position of the original motor model can be changed based on the gain information and the flux error information, so that the pole position of the original motor model after the change is in a stable state, thereby achieving the purpose of allowing the motor model to operate stably at any speed and under any working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0035] Figure 1 It is a schematic diagram of the device structure of the hardware operating environment of the asynchronous motor stability control device involved in the embodiment of the present invention;

[0036] Figure 2 It is a flow chart of a first embodiment of a stable control method for an asynchronous motor according to the present invention;

[0037] Figure 3 It is a schematic flow chart of the stable control method of the asynchronous motor of the present invention;

[0038] Figure 4 This is the waveform diagram of the asynchronous motor not being stable;

[0039] Figure 5 A schematic diagram of a stable waveform of a stable control method for an asynchronous motor of the present invention;

[0040] Figure 6 It is a functional module diagram of an embodiment of a stable control system of an asynchronous motor of the present invention. DETAILED DESCRIPTION

[0041] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0043] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0044] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" 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 an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] like Figure 1 As shown, Figure 1 It is a schematic diagram of the device structure of the hardware operating environment of the asynchronous motor stability control device involved in the embodiment of the present invention.

[0047] like Figure 1 As shown, in the hardware operating environment of the stability control device of the asynchronous motor, the stability control device may include: a processor 1001, such as a CPU, a network interface 1004, a memory 1005, and a communication bus 1002. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory or a stable memory (non-volatile memory), such as a disk memory. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0048] Those skilled in the art will understand that Figure 1 The stability control device structure shown in the figure does not constitute a limitation of the stability control device, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0049] like Figure 1 As shown, the memory 1005 as a computer storage medium may include an operating system, a network communication module, and a stable control program for an asynchronous motor.

[0050] exist Figure 1 In the device shown, the network interface 1004 is mainly used to connect to the background server and perform data communication with the background server; and the processor 1001 can be used to call the stability control program of the asynchronous motor stored in the memory 1005 and perform the following operations:

[0051] Acquire a synchronous current of the asynchronous motor in a synchronous rotating coordinate system and a flux linkage error value of the asynchronous motor, and determine a gain correction matrix based on the synchronous current;

[0052] A voltage error value is obtained based on the product of the gain correction matrix and the flux error value, and the voltage error value is fed back to the rotor flux observer of the asynchronous motor to control the asynchronous motor to operate stably.

[0053] Based on the above hardware structure, the overall concept of each embodiment of the stable control method of the asynchronous motor of the present invention is proposed.

[0054] Nowadays, in the transmission system of asynchronous motors, common speed closed-loop control methods include: model reference adaptive method, full-order adaptive observer method, reduced-order observer method, extended Kalman filter method, sliding mode observer method, etc. However, when controlling the motor by the above methods, it is easy to cause the motor to run unstably at certain speeds or under certain working conditions.

[0055] In order to solve the above problem, the present invention proposes a stable control method for an asynchronous motor.

[0056] Based on the overall concept of the various embodiments of the stable control method for an asynchronous motor of the present invention, various embodiments of the stable control method for an asynchronous motor of the present invention are proposed.

[0057] Please refer to Figure 2 , Figure 2 It should be noted that, although the flowchart shows a logical sequence, in some cases, the steps of the method for stable control of an asynchronous motor of the present invention can be performed in a different order than that shown here.

[0058] In this embodiment, the execution subject of the asynchronous motor stability control method may be an asynchronous motor stability control device, and the asynchronous motor stability control device may be a computer, a mobile phone, etc. In this embodiment, for ease of description, the execution subject is omitted to illustrate each embodiment.

[0059] In this embodiment, the stable control method of an asynchronous motor is applied to a stable control system of an asynchronous motor including a rotor flux observer, wherein the stable control method of the asynchronous motor includes:

[0060] Step S10, obtaining a synchronous current of the asynchronous motor in a synchronous rotating coordinate system and a flux error value of the asynchronous motor, and determining a gain correction matrix based on the synchronous current;

[0061] In the field of motor control, commonly used coordinate systems include three-phase coordinate system, synchronous rotating coordinate system and stationary coordinate system. When performing stable control on an asynchronous motor, it is necessary to obtain the three-phase phase voltage of the motor stator winding in the three-phase coordinate system based on actual measurement or internal estimation based on the motor controller of the asynchronous motor, as well as the phase current of the motor stator. In order to facilitate judgment of the current operating state of the motor, the three-phase phase voltage and phase current can also be transformed through park to obtain the synchronous voltage and synchronous current of the three-phase phase voltage in the synchronous rotating coordinate system.

[0062] It should be understood that both the synchronous current and the synchronous voltage are matrices with two rows and one column.

[0063] The phase current measured by the asynchronous motor during operation is obtained, and then the phase current measured in the three-phase coordinate system is converted into the current in the synchronous rotating coordinate system through park transformation, and the converted current is used as the synchronous current, and then the gain correction matrix corresponding to the asynchronous motor is determined based on the synchronous current, and the flux error value generated in the current operating state of the asynchronous motor is obtained synchronously or asynchronously.

[0064] Step S20, obtaining a voltage error value based on the product of the gain correction matrix and the flux error value, and feeding back the voltage error value to the rotor flux observer of the asynchronous motor to control the asynchronous motor to operate stably.

[0065] It should be understood that the gain correction matrix is ​​a matrix with two rows and two columns, while the flux error value is a matrix with two rows and one column. The rotor flux observer can be an algorithm or device that uses stator voltage, stator current or rotor speed signal to observe the phase and amplitude of the rotor flux.

[0066] It should be noted that in the field of motor control, the flux position is not measured directly by sensors, but by rotor flux observers. Therefore, when the data observed by the rotor flux observer is inaccurate, the stability of the motor operation cannot be controlled. If the phase observed by the rotor flux observer is inaccurate, the direct-axis component and the quadrature-axis component of the stator current cannot be completely decoupled, which will cause oscillation and instability of the motor. Therefore, the voltage error value refers to the error value of the stator voltage obtained by the rotor flux observer.

[0067] After obtaining the gain correction matrix and the flux error value, the gain correction matrix and the matrix corresponding to the flux error value are multiplied to obtain a new matrix, and then the voltage error value is obtained based on this new matrix, and then the voltage error value is fed back to the rotor flux observer, so that the phase and amplitude observed by the rotor flux observer are accurate, so that the asynchronous motor can be controlled to enter a stable operating state based on the accurate phase and amplitude.

[0068] For example, in a feasible implementation, the asynchronous motor is controlled by a preset control cycle, and the data obtained in the current control cycle can be used to adjust the data of the next control cycle, so that the operation of the asynchronous motor is stable. For example, the synchronous current of the current control cycle can be calculated by the following formula:

[0069]

[0070] The matrix on the left side of the equation is the synchronous current in the synchronous rotating coordinate system, and the matrix on the right side of the equation is a ,i b ,i c is the phase current collected in the three-phase coordinate system, It is the flux orientation angle obtained in the previous control cycle.

[0071] In addition to determining the synchronous current based on the phase current in the three-phase coordinate system and determining the gain correction matrix based on the synchronous current, it is also necessary to obtain the flux error value of the asynchronous motor, and then obtain the stator voltage error value of the rotor flux observer based on the product of the gain correction matrix and the flux error value, and feed the stator voltage error value back to the rotor flux observer, so that the rotor flux observer can observe the correct phase and amplitude based on the stator voltage error value, and then control the asynchronous motor to operate stably according to the correct phase and amplitude.

[0072] In an embodiment of the present invention, the synchronous current of the asynchronous motor and the flux error value of the asynchronous motor in a synchronous rotating coordinate system are obtained, and a gain correction matrix is ​​determined based on the synchronous current, so as to obtain the flux error information of the motor during current operation and the gain information required to correct the stable operation of the motor; then, the voltage error value is obtained by multiplying the gain correction matrix and the flux error value, and the voltage error value is fed back to the rotor flux observer, so that the pole position of the original motor model can be changed based on the gain information and the flux error information, so that the pole position of the original motor model after the change is in a stable state, thereby achieving the purpose of allowing the motor model to operate stably at any speed and any working condition.

[0073] Furthermore, based on the first embodiment of the stable control method for an asynchronous motor of the present invention, a second embodiment of the stable control method for an asynchronous motor of the present invention is proposed.

[0074] In this embodiment, the synchronous current includes: a direct-axis current and a quadrature-axis current, and the above step S10 includes:

[0075] Step S101, determining an initial two-dimensional matrix based on the direct-axis current and the quadrature-axis current;

[0076] After the phase currents in the three-phase coordinate system are converted into direct-axis currents and quadrature-axis currents through park transformation, the direct-axis currents and quadrature-axis currents can be used as elements at specific positions in a two-dimensional matrix, and then other positions in the two-dimensional matrix are filled with constants or other parameters, and the filled two-dimensional matrix is ​​used as the initial two-dimensional matrix.

[0077] It should be understood that there is a preset ratio relationship between the elements at specific positions. For example, the technician sets the 11th position (the first row and the first column) and the 21st position (the second row and the first column) in the matrix as specific positions, and the ratio relationship of the elements at the specific positions is -i d / i q When the stability control system needs to maintain the ratio of the element at position 11 to the element at position 21 in the initial two-dimensional matrix to be -i d / i q In another feasible implementation, the ratio of the element at position 21 to the element at position 11 may also be -w s *τ r , where w s is the slip frequency, τ r is the motor rotor time constant.

[0078] For example, in one possible implementation, assuming that d is the direct axis current, i q For the quadrature axis current, when the specific positions are numbers 11 and 21 in the matrix, the initial two-dimensional matrix can be:

[0079]

[0080] In addition, the direct-axis current and the quadrature-axis current can be multiplied to obtain i d i q Then, i d 2 and i d i q As the basic element of the matrix, by d 2 and multiple i d i q Combine to get the initial two-dimensional matrix. For example, the initial two-dimensional matrix can also be:

[0081]

[0082] Step S102, determining a sum of the square of the direct-axis current and the square of the quadrature-axis current, and obtaining a matrix coefficient based on the inverse of the sum;

[0083] After obtaining the numerical values ​​of the direct-axis current and the quadrature-axis current, the square of the direct-axis current and the square of the quadrature-axis current can also be calculated, and then the square of the direct-axis current and the square of the quadrature-axis current are added to obtain the sum, and the sum is inverted, and the inverse of the sum obtained by the inversion calculation is used as the matrix coefficient.

[0084] Step S103, multiplying the matrix coefficients by the initial two-dimensional matrix to obtain a gain correction matrix.

[0085] After obtaining the matrix coefficients and the initial two-dimensional matrix, the matrix coefficients and the initial two-dimensional matrix are multiplied to obtain a new matrix, and a gain correction matrix is ​​obtained based on the new matrix.

[0086] For example, in one possible implementation, the matrix coefficients may be:

[0087]

[0088] Based on this, the gain correction matrix G can be:

[0089]

[0090] Optionally, in a feasible embodiment, before the above step S20, the method further includes:

[0091] Step S100: obtaining a preset gain coefficient;

[0092] It should be noted that the gain coefficient is a parameter set by technicians to control the convergence speed during matrix multiplication, and the parameter value is greater than zero.

[0093] In order to control the convergence speed when the gain correction matrix and the flux error value are multiplied, it is also necessary to obtain the gain coefficient set by the technician.

[0094] Based on this, the above step S20 includes:

[0095] Step S201, obtaining a voltage error value based on the product of a preset gain coefficient, the gain correction matrix and the flux error value.

[0096] After obtaining the gain coefficient set by the technician, the flux error value generated during the motor flux position observation process, and the gain correction matrix based on the synchronous current, the gain coefficient, the flux error value and the gain correction matrix are multiplied together, and the voltage error value is obtained based on the matrix obtained by the multiplication.

[0097] For example, in a feasible embodiment, the gain coefficient is k, the flux error value is r, and the gain correction matrix is:

[0098]

[0099] Then the voltage error value can be expressed as:

[0100]

[0101] By obtaining the gain coefficient, the convergence speed of the multiplication process of the flux error value and the gain correction matrix can be flexibly controlled, so that the voltage error value can be obtained in a timely and accurate manner, reducing the time it takes for the motor to enter a stable state.

[0102] In this embodiment, an initial two-dimensional matrix is ​​obtained through the direct-axis current and the cross-axis current, and the matrix coefficients are obtained through the direct-axis current and the cross-axis current, and then the gain correction matrix is ​​determined based on the matrix coefficients and the initial two-dimensional matrix. Alternatively, the gain correction matrix is ​​determined based on the gain coefficient matrix coefficients and the initial two-dimensional matrix. This can timely and accurately adjust the pole position of the motor during operation based on the direct-axis and cross-axis alternating currents generated during the operation of the asynchronous motor, thereby allowing the asynchronous motor to enter a stable state.

[0103] Furthermore, based on the first and second embodiments of the stable control method for an asynchronous motor of the present invention, a third embodiment of the stable control method for an asynchronous motor of the present invention is proposed.

[0104] In this embodiment, the above step S10 further includes:

[0105] Step S105, obtaining a flux estimation value based on the synchronous voltage and the synchronous current of the asynchronous motor in a synchronous rotating coordinate system, and obtaining a flux given value based on the synchronous current;

[0106] It should be understood that both the flux estimation value and the flux given value represent the position (phase and amplitude) of the rotor flux in the asynchronous motor.

[0107] During the operation of the asynchronous motor, the three-phase phase voltage of the asynchronous motor in the three-phase coordinate system can also be collected, and then the three-phase phase voltage is converted into a synchronous voltage in the synchronous rotating coordinate system based on the park transformation, and then the magnetic flux estimation value of the asynchronous motor is obtained based on the synchronous voltage and the synchronous current, and the magnetic flux given value of the asynchronous motor is obtained based on the synchronous current.

[0108] For example, in a feasible embodiment, the synchronous voltage may be calculated by the following formula:

[0109]

[0110] The left side of the equation is the synchronous voltage, and the right side of the equation is va, vb, v c is the three-phase voltage, It is still the flux orientation angle obtained in the previous control cycle. After the synchronous voltage is obtained through the above formula, the flux estimation value and the flux given value are determined based on the synchronous voltage and the synchronous current.

[0111] In one feasible embodiment, the above step S105 includes:

[0112] Step S1051, determining a given flux value corresponding to the synchronous current based on a preset rotor flux given relationship;

[0113] It should be understood that the rotor flux given relationship reflects the mapping relationship between the direct-axis current in the synchronous current and the direct-axis component of the flux given value.

[0114] When calculating the given flux linkage value, the given flux linkage value can be indirectly obtained by calculating the direct-axis component and the quadrature-axis component of the given flux linkage value. Therefore, the synchronous current is first decomposed into the direct-axis current and the quadrature-axis current. Then, based on the mapping relationship between the direct-axis current in the synchronous current and the direct-axis component of the given flux linkage value, the direct-axis component of the given flux linkage value is determined. Then, the quadrature-axis component of the given flux linkage value is assigned to a constant. Then, the direct-axis component and the quadrature-axis component of the given flux linkage value are superimposed, and the sum obtained is used as the given flux linkage value.

[0115] For example, to obtain an example, the rotor flux given relationship can be:

[0116]

[0117] Among them, p is the derivative operator, L m is the motor mutual inductance, τ r is the motor rotor time constant, i d is the direct axis current in the synchronous current, λ * rd is the direct-axis component of the flux linkage given value. Then, the quadrature-axis component of the flux linkage given value is set to a constant, for example: * rq =0, where λ * rq is the quadrature axis component, and then the direct axis component is superimposed with the quadrature axis component to obtain the given value of magnetic flux λ * r .

[0118] Step S1052: determining a flux estimation value corresponding to both the synchronous current and the synchronous voltage based on a rotor flux observer of the asynchronous motor.

[0119] It should be noted that the rotor flux observer can reflect the mapping relationship between the synchronous current, the synchronous voltage and the flux estimation value.

[0120] After obtaining the synchronous voltage based on the three-phase phase voltage and the synchronous current based on the phase current, the flux estimation value corresponding to both the synchronous current and the synchronous voltage is calculated based on the mapping relationship between the synchronous current and the synchronous voltage and the flux estimation value.

[0121] For example, the rotor flux observer stores the following formula. During the motor stability control process, the flux estimation value can be calculated by the following calculation formula:

[0122]

[0123] Among them, p is the derivative operator, L m is the motor mutual inductance, L r is the motor rotor inductance, R s is the motor stator resistance, L σ is the total leakage inductance of the motor, J is the second-order matrix is the estimated value of magnetic linkage, is the flux orientation angle of the previous control cycle, v dq is the synchronous voltage, i dq is the synchronous current.

[0124] After determining the synchronous current and synchronous voltage, the flux linkage estimation value is obtained based on the above formula Through the above-mentioned rotor flux given relationship and rotor flux observation relationship, the flux estimation value and the flux given value can be obtained quickly and accurately. Since this scheme is based on the calculation of the direct-axis component and the quadrature-axis component of the flux given value respectively, this scheme also avoids the dependence on the motor rotor resistance parameters by simplifying the given flux model (flux given relationship).

[0125] Optionally, in a feasible embodiment, the above step S105 further includes:

[0126] Step S1053, converting the synchronous voltage of the asynchronous motor in the synchronous rotating coordinate system into a stationary voltage in the stationary coordinate system, and converting the synchronous current into a stationary current in the stationary coordinate system;

[0127] In addition to directly determining the flux error value based on the synchronous voltage and synchronous current in the synchronous rotating coordinate system, the synchronous voltage and synchronous current can also be converted into a stationary coordinate system, and the voltage corresponding to the synchronous voltage in the stationary coordinate system is used as the stationary voltage, and the current corresponding to the synchronous current in the stationary coordinate system is used as the stationary current.

[0128] Step S1054: obtaining a flux linkage estimation value based on the quiescent voltage and the quiescent current, and obtaining a flux linkage set value based on the quiescent current.

[0129] After the quiescent voltage and quiescent current are obtained, the flux estimation value is obtained based on the mapping relationship between the quiescent voltage and quiescent current and the flux estimation value, and the flux given value is obtained based on the mapping relationship between the quiescent current and the flux estimation value.

[0130] It should be understood that the stationary voltage and stationary current in the stationary coordinate system also have components of the α and β axes. Therefore, when performing calculations in the stationary coordinate system, the flux estimation value and the flux given value can be calculated by formulas similar to the above-mentioned rotor flux given relationship and stored in the rotor flux observer.

[0131] In addition, it should be noted that, in this embodiment, only the gain correction matrix needs to be calculated based on the synchronous current, and the flux linkage given value and the flux linkage estimated value can be calculated based on the static voltage and the static current. If the three-phase phase voltage and phase current can be directly converted into the static voltage and static current in the static coordinate system, there is no need to obtain the static current and static voltage based on the synchronous current and the synchronous voltage.

[0132] For example, in a feasible embodiment, after obtaining the synchronous voltage and synchronous current in the synchronous rotating coordinate system, the given flux value and the estimated flux value can be directly obtained in the synchronous rotating coordinate system based on the mapping relationship between the synchronous voltage and the synchronous current and the given flux value and the estimated flux value; or, the synchronous voltage and the synchronous current can be converted into the stationary coordinate system to obtain the stationary voltage and the stationary current, and then the given flux value and the estimated flux value can be obtained based on the mapping relationship between the stationary voltage and the stationary current and the given flux value and the estimated flux value. In actual application, the method of obtaining the given flux value and the estimated flux value can be flexibly selected according to the difficulty of data acquisition or the amount of calculation of data calculation.

[0133] Step S106: taking the difference between the given flux value and the estimated flux value as a flux error value.

[0134] After obtaining the flux set value and the flux estimated value through the synchronous current and the synchronous voltage, the flux set value and the flux error value are subtracted and the difference is used as the flux error value.

[0135] For example, in one possible embodiment, the flux error value The estimated value of magnetic flux is The given value of magnetic flux is λ * r .

[0136] In this embodiment, the estimated flux value and the given flux value are calculated by synchronous voltage and synchronous current, and the estimated flux value and the given flux value are calculated by static voltage and static current, thereby improving the portability and scenario applicability of data calculation.

[0137] Furthermore, based on the first to third embodiments of the stable control method for an asynchronous motor of the present invention, a fourth embodiment of the stable control method for an asynchronous motor of the present invention is proposed.

[0138] In this embodiment, after the above step S20, the method further includes:

[0139] Step S30, obtaining a final flux estimation value of the asynchronous motor, wherein the final flux estimation value includes a direct-axis flux estimation value and a quadrature-axis flux estimation value;

[0140] After the voltage error value is fed back to the rotor flux observer, the rotor position calculated by the rotor flux observer will be accurate, and then the asynchronous motor is controlled to be in a stable state based on the accurate rotor position. Then, the flux estimation value of the asynchronous motor in a stable state is obtained (which can be calculated according to the formula in the above rotor flux observer), and the flux estimation value in the stable state is used as the final flux estimation value, wherein the final flux estimation value can be decomposed into a direct-axis flux estimation value and a quadrature-axis flux estimation value.

[0141] For example, in a feasible embodiment, the calculation formula for obtaining the estimated value of the flux linkage of the asynchronous motor in a stable state is as follows:

[0142]

[0143] It can be obtained that: The difference between the above equation and the rotor flux observation relationship is: is the voltage error value. In this formula, k is the observer gain coefficient (k>0), G is the gain correction matrix, is the flux error value. When the asynchronous motor is in a stable state, the is the final magnetic linkage estimate.

[0144] It should be noted that In is the estimated value of flux linkage obtained in the previous control cycle. The left side of the equation is In is the final flux linkage estimate obtained in the steady state.

[0145] Step S40, determining a slip frequency based on the direct-axis flux estimation value and the quadrature-axis current, and performing proportional integration on the quadrature-axis flux estimation value to determine a stator frequency;

[0146] After obtaining the direct-axis flux estimation value of the final flux estimation value, the slip frequency corresponding to the direct-axis flux estimation value and the quadrature-axis current is obtained through the mapping relationship between the direct-axis flux estimation value, the quadrature-axis current and the slip frequency. After obtaining the quadrature-axis flux estimation value of the final flux estimation value, the quadrature-axis flux estimation value can be proportionally integrated by a proportional-integral (PI) regulator to obtain the stator frequency. In addition, after obtaining the stator frequency of this control cycle, the flux orientation angle can also be obtained by integrating the stator frequency. So that the next control cycle is based on Calculate the synchronous voltage and synchronous current.

[0147] For example, in a feasible embodiment, the slip frequency can be calculated by the following formula:

[0148]

[0149] in, is the slip frequency. The other parameters have been explained in the previous article and will not be repeated here.

[0150] In step S50, a rotation speed estimation value is obtained based on a difference between the stator frequency and the slip frequency.

[0151] After obtaining the stator frequency and the slip frequency, the stator frequency is subtracted from the slip frequency to obtain the speed estimate. Since high-frequency noise is generated in the calculation from determining the synchronous current to obtaining the speed estimate, and the speed estimate needs to be fed back to the asynchronous motor, and the asynchronous motor can only receive low-frequency signals, after obtaining the speed estimate, the speed estimate will also be low-pass filtered to obtain the speed estimate that can be fed back to the asynchronous motor.

[0152] For example, at the stator frequency When the speed is estimated There is still high-frequency noise in the speed estimate obtained by subtraction, so the speed estimate needs to be Low-pass filtering is performed (for example, filtering is performed by a low-pass filter, and the filtering method is not limited here), and the filtered speed estimation value is transmitted to the asynchronous motor, so that the speed of the asynchronous motor can be accurately controlled.

[0153] Please refer to Figure 3 , Figure 3 The figure is a flow chart of the method for stable control of an asynchronous motor of the present invention, wherein the rotor flux observation model stores the rotor flux observation relationship, the rotor flux given model stores the rotor flux given relationship, the slip estimation module is used to calculate the slip frequency, and the flux angle and custom frequency estimation module is used to calculate the flux angle and stator frequency. Figure 3 In, v abc ,iabc They represent the phase voltage and phase current in the three-phase coordinate system respectively. The synchronous voltage v is obtained by performing park conversion on the phase voltage. dq Then, the rotor flux observation model is used to obtain the flux estimation value based on the synchronous voltage and synchronous current, and the rotor flux given model is used to obtain the flux given value based on the synchronous current. Then, the flux estimation value and the flux given value are subtracted to obtain the flux error value Δλ. r , and obtain the gain correction matrix through the synchronous current, then use the product of the gain coefficient k, the gain correction matrix and the flux error value as the voltage error value, and feed the voltage error value back to the rotor flux observation model to make the asynchronous motor stable. Then use the estimated flux value of the asynchronous motor under stability as the final estimated flux value, calculate the slip frequency and stator frequency based on the final estimated flux value, then make a difference between the stator frequency and the slip frequency to obtain the speed 1 (speed estimate), and filter it through a low-pass filter to obtain the speed 2, then pass the speed 2 to the speed current feedback controller, and then check the motor speed after control through PWM modulation.

[0154] Please refer to Figure 4 and Figure 5 , Figure 4 This is the waveform diagram of the asynchronous motor not in a stable state. Figure 5 Schematic diagram of stable waveform of the stable control method of the asynchronous motor of the present invention, wherein: Figure 4 and Figure 5 The test conditions are the same: the motor runs at full load at a constant speed of 90RPM.

[0155] in, Figure 4 The A in represents the three-phase current waveform of the motor stator, and the current unit is A; Figure 4 The B in the figure represents the motor load level, which corresponds to the full load level of a 2-pole asynchronous motor rated at 5.5kW / 50Hz, in Nm. Figure 4 The C in represents the actual speed of the motor, in RPM; Figure 4 The D in represents the inverter DC bus voltage, in V. Figure 4 It can be seen that when the motor is running at full load at a constant speed of 90RPM, the speed appears to be flying, that is, the motor is not in a stable state.

[0156] Figure 5 X, Y, Z and Q in Figure 4 A, B, C and D in the above table correspond to each other, but Figure 5 is obtained by the stable control method proposed by the present invention, from Figure 5It can be seen from the figure that when the motor is running at full load at a constant speed of 90RPM, the speed setting is ramped down from 90RPM to -90RPM within 1.2s, and the load remains constant. In other words, the stable control method proposed in the present invention can keep the motor in a stable state at all times.

[0157] In this embodiment, the rotation speed is calculated by using the final flux estimation value, which can prove that the rotation speed of the asynchronous motor in a stable state can be accurately controlled.

[0158] In addition, the present invention also provides a stable control system for an asynchronous motor.

[0159] Please refer to Figure 6 , the stability control system of the asynchronous motor further includes:

[0160] The data acquisition module 10 is used to acquire the synchronous current of the asynchronous motor and the flux error value of the asynchronous motor in the synchronous rotating coordinate system, and determine the gain correction matrix based on the synchronous current;

[0161] The gain correction feedback module 20 is used to obtain a voltage error value based on the product of the gain correction matrix and the flux error value, and feed the voltage error value back to the rotor flux observer of the asynchronous motor to control the asynchronous motor to run stably.

[0162] Optionally, the synchronous current includes: a direct-axis current and a quadrature-axis current, and the data acquisition module 10 includes:

[0163] an initial matrix determining unit, configured to determine an initial two-dimensional matrix based on the direct-axis current and the quadrature-axis current;

[0164] A matrix coefficient determination unit, used to determine a sum of the square of the direct-axis current and the square of the quadrature-axis current, and obtain a matrix coefficient based on the inverse of the sum;

[0165] The correction matrix determination unit is used to multiply the matrix coefficients with the initial two-dimensional matrix to obtain a gain correction matrix.

[0166] Optionally, the gain correction feedback module 20 further includes:

[0167] The data multiplication unit is used to obtain a voltage error value based on the product of a preset gain coefficient, the gain correction matrix and the flux error value.

[0168] Optionally, the stability control system of the asynchronous motor further includes:

[0169] An estimated value acquisition module, used for acquiring a final flux estimation value of the asynchronous motor, wherein the final flux estimation value includes a direct-axis flux estimation value and a quadrature-axis flux estimation value;

[0170] A frequency calculation module, configured to determine a slip frequency based on the direct-axis flux estimation value and the quadrature-axis current, and to determine a stator frequency by proportionally integrating the quadrature-axis flux estimation value;

[0171] The frequency difference module is used to obtain a rotation speed estimation value based on a difference between the stator frequency and the slip frequency.

[0172] Optionally, the data acquisition module further includes:

[0173] a flux position determination unit, configured to obtain a flux estimation value based on a synchronous voltage of the asynchronous motor in a synchronous rotating coordinate system and the synchronous current, and to obtain a flux given value based on the synchronous current;

[0174] The flux linkage error determination unit is configured to obtain a flux linkage error value based on a difference between the given flux linkage value and the estimated flux linkage value.

[0175] Optionally, the magnetic flux position determining unit includes:

[0176] A first determining subunit, configured to determine a given flux value corresponding to the synchronous current based on a preset rotor flux given relationship;

[0177] The second determining subunit is used to determine a flux estimation value corresponding to both the synchronous current and the synchronous voltage based on a rotor flux observer of the asynchronous motor.

[0178] Optionally, the magnetic flux position determining unit further includes:

[0179] A data conversion subunit, used for converting the synchronous voltage of the asynchronous motor in a synchronous rotating coordinate system into a stationary voltage in a stationary coordinate system, and converting the synchronous current into a stationary current in a stationary coordinate system;

[0180] The data calculation subunit is used to obtain a flux linkage estimation value based on the static voltage and the static current, and to obtain a flux linkage given value based on the static current.

[0181] Among them, the functional implementation of each module in the above-mentioned asynchronous motor stability control system corresponds to the various steps in the above-mentioned asynchronous motor stability control method embodiment, and its functions and implementation processes are no longer repeated here one by one.

[0182] In addition, the present invention also proposes a stable control device for an asynchronous motor, which includes: a memory, a processor, and a stable control program for the asynchronous motor stored in the memory and executable on the processor, and when the stable control program for the asynchronous motor is executed by the processor, the steps of the stable control method for the asynchronous motor of the present invention as described above are implemented.

[0183] The specific embodiments of the stabilization control device for an asynchronous motor of the present invention are substantially the same as the embodiments of the stabilization control method for an asynchronous motor described above, and are not described in detail herein.

[0184] In addition, the present invention further proposes a storage medium on which a stabilization control program for an asynchronous motor is stored. When the stabilization control program for an asynchronous motor is executed by a processor, the steps of the stabilization control method for an asynchronous motor of the present invention as described above are implemented.

[0185] The specific embodiments of the storage medium of the present invention are basically the same as the embodiments of the above-mentioned method for stable control of an asynchronous motor, and will not be described in detail here.

[0186] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0187] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0188] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a disk, or an optical disk), and includes a number of instructions for a terminal device (which can be a car computer, a smart phone, a computer, or a server, etc.) to execute the methods described in each embodiment of the present application.

[0189] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A stable control method for an asynchronous motor, characterized in that: The stable control method of the asynchronous motor comprises: Acquire a synchronous current of the asynchronous motor in a synchronous rotating coordinate system and a flux linkage error value of the asynchronous motor, and determine a gain correction matrix based on the synchronous current; A voltage error value is obtained based on the product of the gain correction matrix and the flux error value, and the voltage error value is fed back to the rotor flux observer of the asynchronous motor to control the asynchronous motor to operate stably.

2. The method for stable control of an asynchronous motor according to claim 1, characterized in that: The synchronous current includes: a direct-axis current and a quadrature-axis current, and the step of determining a gain correction matrix based on the synchronous current includes: determining an initial two-dimensional matrix based on the direct-axis current and the quadrature-axis current; Determine a sum of the square of the direct-axis current and the square of the quadrature-axis current, and obtain a matrix coefficient based on the inverse of the sum; The matrix coefficients are multiplied by the initial two-dimensional matrix to obtain a gain correction matrix.

3. The method for stable control of an asynchronous motor according to claim 1, characterized in that: The step of obtaining the voltage error value based on the product of the gain correction matrix and the flux error value comprises: A voltage error value is obtained based on the product of a preset gain coefficient, the gain correction matrix and the flux error value.

4. The method for stable control of an asynchronous motor according to claim 2, characterized in that: After the step of feeding back the voltage error value to the rotor flux observer of the asynchronous motor, the method further includes: Acquire a final flux estimation value of the asynchronous motor, wherein the final flux estimation value includes a direct-axis flux estimation value and a quadrature-axis flux estimation value; Determine the slip frequency based on the direct-axis flux estimation value and the quadrature-axis current, and determine the stator frequency by proportionally integrating the quadrature-axis flux estimation value; A speed estimate is obtained based on a difference between the stator frequency and the slip frequency.

5. The method for stable control of an asynchronous motor according to claim 1, characterized in that: The step of obtaining the flux error value of the asynchronous motor comprises: Obtaining a flux linkage estimation value based on a synchronous voltage and a synchronous current of the asynchronous motor in a synchronous rotating coordinate system, and obtaining a flux linkage given value based on the synchronous current; A flux error value is obtained based on a difference between the given flux value and the estimated flux value.

6. The method for stable control of an asynchronous motor according to claim 5, characterized in that: The step of obtaining a flux linkage estimation value based on the synchronous voltage and the synchronous current of the asynchronous motor in a synchronous rotating coordinate system, and obtaining a flux linkage given value based on the synchronous current comprises: Determining a flux setting value corresponding to the synchronous current based on a preset rotor flux setting relationship; A rotor flux observer based on the asynchronous motor determines flux estimation values ​​corresponding to both the synchronous current and the synchronous voltage.

7. The method for stable control of an asynchronous motor according to claim 5, characterized in that: The step of obtaining a flux linkage estimation value based on the synchronous voltage and the synchronous current of the asynchronous motor in a synchronous rotating coordinate system, and obtaining a flux linkage given value based on the synchronous current comprises: Converting the synchronous voltage of the asynchronous motor in a synchronous rotating coordinate system into a stationary voltage in a stationary coordinate system, and converting the synchronous current into a stationary current in a stationary coordinate system; A flux linkage estimation value is obtained based on the static voltage and the static current, and a flux linkage set value is obtained based on the static current.

8. A stable control system for an asynchronous motor, characterized in that: The stability control system of the asynchronous motor also includes: A data acquisition module, used to acquire a synchronous current of the asynchronous motor and a flux error value of the asynchronous motor in a synchronous rotating coordinate system, and determine a gain correction matrix based on the synchronous current; The gain correction feedback module is used to obtain a voltage error value based on the product of the gain correction matrix and the flux error value, and feed the voltage error value back to the rotor flux observer of the asynchronous motor to control the asynchronous motor to run stably.

9. A stable control device for an asynchronous motor, characterized in that: The asynchronous motor stability control device comprises: a memory, a processor and an asynchronous motor stability control program stored in the memory and executable on the processor. When the asynchronous motor stability control program is executed by the processor, the steps of the asynchronous motor stability control method as described in any one of claims 1 to 7 are implemented.

10. A storage medium, characterized in that: The storage medium stores a stabilization control program for an asynchronous motor, and when the stabilization control program for an asynchronous motor is executed by a processor, the steps of the stabilization control method for an asynchronous motor according to any one of claims 1 to 7 are implemented.

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