Method and device for generating an ac motor current command

Abstract

This invention discloses a method and apparatus for generating current commands for an AC motor. The method includes: acquiring multiple sets of calibration data for the AC motor, wherein each set of calibration data includes direct-axis current, quadrature-axis current, motor torque, a two-dimensional mapping table, and a preset noise curve. The two-dimensional mapping table characterizes the mapping relationship between the direct-axis current, quadrature-axis current, and motor torque, and the preset noise curve characterizes the maximum torque-to-current ratio control curve of the AC motor; converting the multiple sets of calibration data using interpolation to obtain multiple equal-torque curves, wherein the torque values ​​of the multiple equal-torque curves are different; determining a target noise curve based on the multiple equal-torque curves, the direct-axis current, and the quadrature-axis current; and generating a motor current command based on the target noise curve. This invention solves the technical problem of low accuracy in generating motor current commands in related technologies.

Description

Technical Field

[0001] This invention relates to the field of data processing, and more specifically, to a method and apparatus for generating AC motor current commands. Background Technology

[0002] In existing technologies, torque control of electric drive systems in new energy vehicles generally uses the maximum torque per ampere (MTPA) control method in the low-to-medium speed range. This method can output maximum torque with minimum current, improving the efficiency of the electric drive system. However, the current command used by the existing MTPA control method cannot achieve optimal motor noise. Excessive noise reduces the subjective driving experience for new energy vehicle users, resulting in a poor driving experience. This leads to low accuracy in generating AC motor current commands.

[0003] There is currently no effective solution to the above problems. Summary of the Invention

[0004] This invention provides a method and apparatus for generating AC motor current commands, which at least solves the technical problem of low accuracy in generating motor current commands in related technologies.

[0005] According to one aspect of the present invention, a method for generating an AC motor current command is provided. The method includes: acquiring multiple sets of calibration data for an AC motor, wherein each set of calibration data includes direct-axis current, quadrature-axis current, motor torque, a two-dimensional mapping table, and a preset noise curve, wherein the two-dimensional mapping table is used to characterize the mapping relationship between the direct-axis current, quadrature-axis current, and motor torque, and the preset noise curve is used to characterize the maximum torque-to-current ratio control curve of the AC motor; converting the multiple sets of calibration data using interpolation to obtain multiple equal torque curves, wherein the torque values ​​of the multiple equal torque curves are different; determining a target noise curve based on the multiple equal torque curves, the direct-axis current, and the quadrature-axis current; and generating a motor current command based on the target noise curve.

[0006] Optionally, the target noise curve is determined based on multiple equal torque curves, direct-axis current, and quadrature-axis current, including: determining the current vector amplitude based on the direct-axis current and quadrature-axis current; obtaining multiple noise curves based on the direct-axis current, quadrature-axis current, and current vector amplitude; and determining the target noise curve based on the multiple equal torque curves and multiple noise curves.

[0007] Optionally, determining a target noise curve based on multiple equal torque curves and multiple noise curves includes: determining a first initial noise curve from multiple noise curves based on the preset noise curve; determining multiple first intersection points of the multiple equal torque curves and multiple noise curves; and fitting the first initial noise curve based on the multiple first intersection points to determine the target noise curve.

[0008] Optionally, determining a target noise curve based on multiple equal torque curves and multiple noise curves includes: fitting multiple equal torque curves to obtain multiple curve equations, wherein the equal torque curves correspond one-to-one with the curve equations; obtaining multiple noise curves based on the multiple curve equations and preset noise curves; determining a second initial noise curve from the multiple noise curves based on the preset noise curves; and fitting the second initial noise curve to obtain the target noise curve.

[0009] Optionally, multiple noise curves are obtained based on multiple curve equations and preset noise curves, including: determining multiple second intersection points between multiple equal torque curves and preset noise curves based on multiple curve equations; drawing multiple circular curves based on preset radii and using multiple second intersection points as centers, determining multiple third intersection points between multiple circular curves and the equal torque curves corresponding to the circular curves; and obtaining multiple noise curves based on multiple third intersection points.

[0010] Optionally, multiple noise curves are obtained based on multiple third intersection points, including: determining the third intersection point located above the preset noise curve as the fourth intersection point; connecting the fourth intersection points located on the same circular curve to obtain multiple noise curves.

[0011] Optionally, the magnitude of the current vector is determined based on the direct-axis current and the quadrature-axis current, including: determining the sum of the squares of the direct-axis current and the quadrature-axis current as the magnitude of the current vector.

[0012] According to one aspect of the present invention, an apparatus for generating an AC motor current command is also provided. The apparatus includes: an acquisition module for acquiring multiple sets of calibration data for an AC motor, wherein each set of calibration data includes direct-axis current, quadrature-axis current, motor torque, a two-dimensional mapping table, and a preset noise curve; the two-dimensional mapping table characterizes the mapping relationship between the direct-axis current, quadrature-axis current, and motor torque; and the preset noise curve characterizes the maximum torque-to-current ratio control curve of the AC motor; a conversion module for converting the multiple sets of calibration data using interpolation to obtain multiple equal-torque curves, wherein the torque values ​​of the multiple equal-torque curves are different; a determination module for determining a target noise curve based on the multiple equal-torque curves, the direct-axis current, and the quadrature-axis current; and a generation module for generating a motor current command based on the target noise curve.

[0013] According to one aspect of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored program, wherein, when the program is running, the method for controlling the device where the computer-readable storage medium is located to perform any of the above-described methods is provided.

[0014] According to another aspect of the present invention, a vehicle is also provided, including: a memory and a processor, the processor being configured to run a program stored in the memory, wherein the program, when running, performs any of the methods described above.

[0015] In this embodiment of the invention, multiple sets of calibration data for an AC motor are acquired. Each set of calibration data includes direct-axis current, quadrature-axis current, motor torque, a two-dimensional mapping table, and a preset noise curve. The two-dimensional mapping table represents the mapping relationship between the direct-axis current, quadrature-axis current, and motor torque, and the preset noise curve represents the maximum torque-to-current ratio control curve of the AC motor. Interpolation is used to transform the multiple sets of calibration data to obtain multiple equal-torque curves, where the torque values ​​of the equal-torque curves are different. Based on the multiple equal-torque curves, the direct-axis current, and the quadrature-axis current, a target noise curve is determined. Based on the target noise curve, a motor current command is generated. It is noteworthy that the motor current command of this invention is generated based on the target noise curve, fully considering the impact of noise on the user's driving experience. Furthermore, by determining the target noise curve based on multiple equal-torque curves, the direct-axis current, and the quadrature-axis current, this invention achieves the goal of accurately generating the motor current command, thereby improving the accuracy of motor current command generation and solving the technical problem of low accuracy in generating motor current commands in related technologies. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0017] Figure 1 This is a flowchart of a method for generating an AC motor current command according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of an optional positive torque region isotorque curve and MTPA curve according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of an optional sorted grouping curve according to an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of an optional modified MTPA calculation curve according to an embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of an optional fitted MTPA correction curve according to an embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram illustrating an optional method for solving the intersection point of the MTPA curve and the equal torque curve according to an embodiment of the present invention.

[0023] Figure 7 This is a schematic diagram of the intersection point of optional circles of different radii and equal torque curves according to an embodiment of the present invention;

[0024] Figure 8 This is a schematic diagram of a grouping curve corresponding to an optional circle of different radii according to an embodiment of the present invention;

[0025] Figure 9 This is a schematic diagram of an optional modified MTPA calculation curve according to an embodiment of the present invention;

[0026] Figure 10 This is an optional fitted MTPA correction curve according to an embodiment of the present invention;

[0027] Figure 11 This is a structural block diagram of an optional permanent magnet synchronous motor function according to an embodiment of the present invention;

[0028] Figure 12 This is a schematic diagram of the structure of an AC motor current command generation device according to an embodiment of the present invention. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] Example 1

[0032] According to an embodiment of the present invention, an embodiment of a method for generating AC motor current commands is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0033] Figure 1 This is a flowchart of a method for generating AC motor current commands according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes the following steps:

[0034] Step S102: Obtain multiple sets of calibration data for the AC motor. Each set of calibration data includes direct-axis current, quadrature-axis current, motor torque, a two-dimensional mapping table, and a preset noise curve. The two-dimensional mapping table is used to characterize the mapping relationship between direct-axis current, quadrature-axis current, and motor torque. The preset noise curve is used to characterize the maximum torque-current ratio control curve of the AC motor.

[0035] The aforementioned direct-axis current can be I d The quadrature-axis current can be I q The motor torque can be T. e The two-dimensional mapping table can be a two-dimensional map, and the preset noise curve mentioned above can be the MTPA control curve L.

[0036] In an optional embodiment, when it is necessary to control a new energy vehicle using the MTPA control method, in order to generate a current control command that can optimize noise, multiple sets of calibration data for the AC motor can first be acquired. Each set of calibration data includes: I d I q T eThe system includes a map and a preset noise curve. The two-dimensional map is used to characterize I. d I q and T e The mapping relationship between them, the MTPA control curve L is used to characterize the maximum torque-current ratio control curve of the AC motor.

[0037] It should be noted that at this time, I in the two-dimensional map d I q The coordinate vector intervals are ΔI d_map ΔI q_map .

[0038] Step S104: Use interpolation to convert multiple sets of calibration data to obtain multiple equal torque curves, wherein the torque values ​​of the multiple equal torque curves are different.

[0039] In one alternative embodiment, the motor torque interval can first be defined as ΔT. e The direct-axis current interval is ΔI d Secondly, multiple sets of calibration data can be converted using interpolation to obtain multiple equal torque curves, where the torque values ​​of the multiple equal torque curves are different.

[0040] In another alternative embodiment, I is interpolated. d I q With T e Converting a 2D map between two Ts e I d with I q A two-dimensional map between them can then be used to obtain ΔT. e ΔI d Multiple curves with equal rotation axes at intervals. Figure 2 This is a schematic diagram of an optional positive torque region isotorque curve and MTPA curve according to an embodiment of the present invention, as shown below. Figure 2 As shown, Figure 2 The display shows the positive torque region. The cluster of curves represents constant torque curves, with I values ​​varying between different state points on the curves. d The minimum unit distance in the axial direction is ΔI. d The torque interval between the constant torque curves is ΔT. e .

[0041] Step S106: Determine the target noise curve based on multiple equal torque curves, direct-axis current, and quadrature-axis current.

[0042] Optionally, the target noise curve is determined based on multiple equal torque curves, direct-axis current, and quadrature-axis current, including: determining the current vector amplitude based on the direct-axis current and quadrature-axis current; obtaining multiple noise curves based on the direct-axis current, quadrature-axis current, and current vector amplitude; and determining the target noise curve based on the multiple equal torque curves and multiple noise curves.

[0043] Optionally, the magnitude of the current vector is determined based on the direct-axis current and the quadrature-axis current, including: determining the sum of the squares of the direct-axis current and the quadrature-axis current as the magnitude of the current vector.

[0044] The aforementioned current vector magnitude can be The noise curve mentioned above can be the MTPA calculation curve, and the target noise curve mentioned above can be the noise curve used to generate current commands. The current commands generated based on the target noise curve can optimize noise and improve the driving experience of new energy vehicle users.

[0045] In one alternative embodiment, I can be calculated at different state points on each isotor curve. d I q The sum of squares of I can be obtained. s The specific calculation formula is as follows:

[0046]

[0047] In another alternative embodiment, such as Figure 2 As shown, connecting the state points with the minimum sum of squares on different constant torque curves yields the MTPA calculation curve L1 (i.e., the noise curve). Using the above formula, multiple noise curves can be obtained by connecting the state points with the minimum sum of squares on multiple constant torque curves. Figure 3 This is a schematic diagram of an optional sorted grouped curve according to an embodiment of the present invention, such as... Figure 3 As shown, for different state points... The results are sorted to obtain the second, third, and fourth smallest current commands, and then connected to the state points corresponding to different arrangements on each equal torque curve to form different grouped curves, represented as follows: Figure 3 The lines L2, L3, and L4 are shown. Curves L2, L3, and L4 become the optimization curves for motor vibration and noise (NVH). As can be seen above, the state points represented by the intersections of lines L1, L2, L3, and L4 with each isotor curve correspond to... The results increase sequentially. It should be noted that the number of noise curves can be determined according to the different electromagnetic schemes of the motor and the different NVH optimization objectives. In this embodiment, four curves are used as an example, but it is not limited to this and can also be five, six, etc.

[0048] Optionally, determining a target noise curve based on multiple equal torque curves and multiple noise curves includes: determining a first initial noise curve from multiple noise curves based on the preset noise curve; determining multiple first intersection points of the multiple equal torque curves and multiple noise curves; and fitting the first initial noise curve based on the multiple first intersection points to determine the target noise curve.

[0049] The first initial noise curve mentioned above can be the torque-current command curve with optimal NVH.

[0050] In an optional embodiment, after determining the preset noise curve, the noise difference between the maximum torque-current ratio curve L (i.e., the preset noise curve) and other calculated NVH optimization curves L2, L3, and L4 under the same torque command conditions can be compared first, and the torque-current command curve with the best NVH (i.e., the first initial noise curve) can be selected. Then, multiple first intersection points of multiple equal torque curves and multiple noise curves can be determined.

[0051] In another alternative embodiment, due to the current amplitude of the optimal NVH curve The torque values ​​are generally greater than the MTPA curve, reducing the efficiency of the electric drive system. Therefore, to ensure a balance between the efficiency and NVH of the electric drive system, adjustments need to be made based on the optimal NVH curve. This involves adjusting the MTPA calculation curve L1 so that the torque value changes from small to large (i.e., along I...). d (negative direction of coordinate axes), I d I q The corresponding state point is selected from the grouped curves obtained in the above steps. Figure 3 This is represented as I increases when the torque increases. d I q The corresponding state points are first selected sequentially on lines L1, L2, L3, and L4, and then selected sequentially on lines L1, L2, L3, and L4 again. The resulting curve is represented as follows. Figure 4 Line L'1 in the middle, Figure 4 This is a schematic diagram of an optional modified MTPA calculation curve according to an embodiment of the present invention, such as... Figure 4 As shown, it can be seen that as the torque value increases, it first gradually moves away from L1, and then eventually returns to L1.

[0052] In yet another alternative embodiment, the following is obtained: Figure 4 After finding line L'1, we can fit line L'1 to obtain the corrected curve of the optimal NVH curve (i.e., the target noise curve). Figure 5 This is a schematic diagram of an optional fitted MTPA correction curve according to an embodiment of the present invention, such as... Figure 5As shown, the state point on line L'1 is the constant rotation region.

[0053] Optionally, determining a target noise curve based on multiple equal torque curves and multiple noise curves includes: fitting multiple equal torque curves to obtain multiple curve equations, wherein the equal torque curves correspond one-to-one with the curve equations; obtaining multiple noise curves based on the multiple curve equations and preset noise curves; determining a second initial noise curve from the multiple noise curves based on the preset noise curves; and fitting the second initial noise curve to obtain the target noise curve.

[0054] The equation of the curve mentioned above can be Y n In this context, the subscript n represents the nth constant torque curve during the torque increase process. Through mathematical calculation, the intersection points of the MTPA curve L with different constant torque curves are obtained and denoted as state points X1, X2, X3, ... X. n ...

[0055] In one optional embodiment, after obtaining multiple equal torque curves and multiple noise curves, the multiple equal torque curves can be fitted to obtain multiple curve equations, wherein the equal torque curves correspond one-to-one with the curve equations.

[0056] Optionally, multiple noise curves are obtained based on multiple curve equations and preset noise curves, including: determining multiple second intersection points between multiple equal torque curves and preset noise curves based on multiple curve equations; drawing multiple circular curves based on preset radii and using multiple second intersection points as centers, determining multiple third intersection points between multiple circular curves and the equal torque curves corresponding to the circular curves; and obtaining multiple noise curves based on multiple third intersection points.

[0057] Figure 6 This is a schematic diagram illustrating an optional method for solving the intersection point of the MTPA curve and the constant torque curve according to an embodiment of the present invention, as shown below. Figure 6 As shown, multiple constant torque curves intersect with curve L to form state points X1, X2, X3...X n ...The aforementioned preset radius can be the radius of a circle centered at the second intersection point, which can be set by the user in advance and can be represented as Δr, Δr*2, or Δr*3. The aforementioned third intersection point can be the intersection point between multiple circular curves and the corresponding isotor curve. Figure 7 This is a schematic diagram of the intersection points of optional circles of different radii and constant torque curves according to an embodiment of the present invention, such as... Figure 7 As shown, the circles with radius Δr and radius Δr*2 intersect with different constant torque curves at points, which is the third intersection point.

[0058] Optionally, multiple noise curves are obtained based on multiple third intersection points, including: determining the third intersection point located above the preset noise curve as the fourth intersection point; connecting the fourth intersection points located on the same circular curve to obtain multiple noise curves.

[0059] The aforementioned fourth intersection point can be a state point formed by the intersection points in the region above the MTPA curve L, which can be denoted as Xmn, where m represents the intersection point on the m-th isotor curve, and n represents the intersection point formed by the circle with radius n*Δr and the isotor curve.

[0060] In one optional embodiment, circles with radii of Δr, Δr*2, Δr*3, etc., are drawn sequentially with each state point X1, X2, X3, etc. as the center, and the circles intersect with the corresponding curve equations Y1, Y2, Y3, etc., to determine the third intersection point.

[0061] In another optional embodiment, state points corresponding to circular transaction points of the same radius on the same set of equal torque curves are sequentially connected to form a curve, such as X. 11 X 21 X 31 …, forming curve L2,X 12 X 22 X 32 …forming curve L3, X 13 X 23 X 33 …forming curve L4, and so on, the lines L2, L3, and L4 shown are NVH optimization curves. Figure 8 This is a schematic diagram of a grouping curve corresponding to an optional circle of different radii according to an embodiment of the present invention, such as... Figure 8 As shown, the state points represented by the intersections of lines L1, L2, L3, and L4 with each isotor curve correspond to... The results increase sequentially.

[0062] In another optional embodiment, after obtaining multiple noise curves, the noise difference between the maximum torque-current ratio curve L and other calculated NVH optimization curves L2, L3, and L4 under the same torque command condition can be compared based on the MTPA curve L (i.e., the preset noise curve). The torque-current command curve with optimal NVH (i.e., the second initial noise curve) is then selected.

[0063] In another alternative embodiment, due to the current amplitude of the optimal NVH curve The values ​​are generally larger than the MTPA curve, which reduces the efficiency of the electric drive system. Therefore, in order to ensure a balance between the efficiency and NVH of the electric drive system, adjustments are made based on the optimal NVH curve. The MTPA curve L is adjusted so that the torque value on it changes from small to large (i.e., along the negative direction of the Id coordinate axis). d Iq The corresponding state point is selected from the grouped curves obtained in the above steps. Figure 9 This is a schematic diagram of an optional modified MTPA calculation curve according to an embodiment of the present invention, such as... Figure 9 As shown, when the torque increases, I d I q The corresponding state points are first selected sequentially on lines L1, L2, L3, and L4, and then sequentially selected on lines L4, L3, L2, and L1. The resulting curve is represented as follows. Figure 9 As shown by line L'1, it can be seen that as the torque value increases, it first gradually moves away from L and then returns to L.

[0064] In another alternative embodiment, after obtaining the second initial noise curve, the second initial noise curve can be fitted to obtain the MTPA correction curve. Figure 10 This is an optional fitted MTPA correction curve according to an embodiment of the present invention, such as... Figure 10 As shown, the state point on line L' is the constant torque region, and the d-axis and q-axis current commands I correspond to different torque commands. d__cmd I q__cmd .

[0065] Step S108: Generate motor current command based on the target noise curve.

[0066] In one optional embodiment, after obtaining the target noise curve, a motor current command can be generated. Based on this command, the noise of the electric drive system can be optimized while ensuring that the efficiency of the electric drive system does not change significantly. This reduces noise in the low-speed range of the electric drive system and improves the user's subjective driving experience.

[0067] This patent proposes a motor control method to reduce noise in electric drive systems. The method utilizes a combination of calculation and calibration to obtain d-axis and q-axis current commands that achieve more significant noise optimization. This current command differs from the current command in traditional maximum torque-to-current ratio (MTPA) control schemes. It optimizes the noise of the electric drive system while ensuring that the system efficiency remains largely unchanged. This reduces noise in the low-speed range of the electric drive system, improving the user's subjective driving experience.

[0068] Figure 11 This is a structural block diagram of an optional permanent magnet synchronous motor function according to an embodiment of the present invention. Figure 11As shown, module 1 is the drive motor; this example uses a three-phase permanent magnet synchronous motor. Module 2 is the inverter module. Module 10 is a position sensor, responsible for detecting the motor rotor position information. As shown in module 3, the sensor can detect the motor rotor position θ and the motor speed information ω. Module 4 is the inversion module, which can convert the three-phase current I of the motor... u_value I v_value I w_value By transforming from a stationary coordinate system to a rotating coordinate system, we obtain the d-axis and q-axis currents I. d_value I q_value In the motor output torque mode, torque command module 5 receives torque commands from the vehicle control unit (VCU) and sends them to torque-current command calculation module 6. The torque-current command calculation module converts the torque command value into the d-axis current command value I. d_cmd and q-axis current command value I q_cmd d, q-axis current command I d_cmd I q_cmd The actual values ​​of the d and q axis currents I d_value I q_value After the difference is calculated, it is input to the PI control module 7, and the d-axis and q-axis voltage commands U are output. d U q After undergoing coordinate transformation by the forward transformation module in module 8, the d and q axis voltage commands are transformed into Alfa and Beta axis voltage commands U. α U β The Alfa and Beta axis voltage commands are input to the Space Vector Pulse Width Modulation (SVPWM) module 9, where they are calculated and output as six Pulse Width Modulation (PWM) duty cycle commands. These commands control the switching on and off of the inverter's six power devices, thereby controlling the motor to output the specified torque. The torque-current command calculation module 6 uses a pre-established map and a lookup table to convert the torque commands into d-axis and q-axis current commands I. d_cmd I q_cmd .

[0069] This invention proposes a noise optimization method for a permanent magnet synchronous motor (PMSM) drive system. This method is based on the known fundamental control theory of PMSMs. Building upon the maximum torque-to-current ratio (MTPA) control method in the low-to-medium speed range, and based on the MTPA control curve, noise optimization is performed by combining practical calibration with theoretical calculations to calibrate the optimal noise curve. Based on this optimal noise curve, the optimal d-axis and q-axis current commands I can be obtained by looking up a table.d_cmd I q_cmd Controlling the electric drive system according to this current command can achieve better motor noise.

[0070] The noise optimization algorithm described in this invention mainly consists of the following steps:

[0071] 1. Calibrate the motor torque map to obtain I. d I q With motor torque T e A two-dimensional map between them.

[0072] 2. Obtain the motor maximum torque-to-current ratio (MTPA) control curve through calibration or calculation.

[0073] 3. Based on the maximum torque-to-current ratio curve, multiple sets of NVH optimization curves are obtained through different calculation methods (Method 1 / Method 2).

[0074] 4. The optimal NVH optimization curve is obtained through actual calibration using bench calibration.

[0075] 5. Implement motor noise optimization control function based on the calibrated NVH optimal curve.

[0076] This invention will describe two different calculation schemes for obtaining the torque-current map that the torque-current command calculation module 6 needs to utilize.

[0077] Specific implementation method 1:

[0078] 1. Obtain the d-axis and q-axis currents I of the motor using the known motor calibration process. d I q With motor torque T e A two-dimensional map between them, where I in the map... d I q The coordinate vector intervals are ΔI d_map ΔI q_map .

[0079] 2. Define the torque interval ΔT e and I d Interval ΔI d By interpolation, I d I q With motor torque T e The two-dimensional map between them is transformed into T. e I d with I q A two-dimensional map between them is obtained, thus yielding a given ΔT. e ΔI d The constant torque curve under intervals, such as Figure 2This section shows the positive torque region. The cluster of curves represents the constant torque curves, where the minimum unit distance between different state points along the Id axis is ΔId, and the torque interval between the constant torque curves is ΔTe.

[0080] 3. On each constant torque curve, calculate the d-axis and q-axis currents I at different state points using the following formula. d I q The sum of squares is the magnitude of the current vector. The state points where the sum of squares is minimized on different constant torque curves are connected to form the MTPA calculation curve. This is represented as... Figure 2 The solid line shown is denoted as line L1. By fitting line L1, the MTPA fitting curve for the positive torque range is obtained, denoted as... Figure 2 The curve shown by the dashed line is denoted as line L.

[0081]

[0082] 4. In the region above line L, calculate the current I on the torque curve according to the method in step 3. d I q Sum of squares, corresponding to different state points The results are sorted to obtain the second, third, and fourth smallest current commands, and then connected to the state points corresponding to different arrangements on each equal torque curve to form different grouped curves, represented as follows: Figure 3 The lines L2, L3, and L4 are shown. Curves L2, L3, and L4 become NVH optimization curves. As can be seen above, the state points represented by the intersections of lines L1, L2, L3, and L4 with each constant torque curve correspond to... The results increase sequentially. In this embodiment, three curves were selected as torque-current correspondence curves in addition to the MTPA curve. The number of curves can be increased or decreased according to different electromagnetic schemes of the motor and different NVH optimization objectives.

[0083] 5. Calibration process of the optimal NVH curve. Based on the calculated or calibrated maximum torque-current ratio (MTPA) curve L, compare the noise difference between the MTPA curve L and other calculated NVH optimization curves L2, L3, and L4 under the same torque command conditions. Then select the torque-current command curve with optimal NVH.

[0084] 6. Due to the current amplitude of the optimal NVH curve The values ​​are generally larger than the MTPA curve, which reduces the efficiency of the electric drive system. Therefore, in order to ensure a balance between the efficiency and NVH of the electric drive system, adjustments are made based on the optimal NVH curve. The MTPA calculation curve L1 is adjusted so that the torque value on it changes from small to large (i.e., along I...). d(negative direction of coordinate axes), I d I q The corresponding state point is selected from the grouped curves obtained in step 4. Figure 3 This is represented as I increases when the torque increases. d I q The corresponding state points are first selected sequentially on lines L1, L2, L3, and L4, and then sequentially on L4, L3, L2, and L1. The resulting curve is represented as follows. Figure 4 As shown by line L'1, it can be seen that as the torque value increases, it first gradually moves away from L1, and eventually returns to L1.

[0085] 7. Fit the line L'1 obtained in step 6 to obtain the corrected curve of the optimal NVH curve, denoted as: Figure 5 The line L' in the diagram represents the constant torque region, and the state points on it correspond to the d-axis and q-axis current commands for different torque commands.

[0086] Regarding steps 1-7, the following points need to be explained:

[0087] The above steps are explained using the positive torque region. The steps for handling the negative torque region are similar and will not be repeated here.

[0088] Steps 4-7 select the area above line L for MTPA curve correction. In fact, the same method can be used to obtain the MTPA curve correction result for the area below line L1.

[0089] In step 5, the grouped curve results are illustrated using lines L1, L2, L3, and L4. In practice, more grouped curves can be selected depending on different needs.

[0090] Specific implementation method 2:

[0091] 1. Obtain the d-axis and q-axis currents I of the motor through the motor calibration process. d I q With motor torque T e A two-dimensional map between them, where I in the map... d I q The coordinate vector intervals are ΔI d_map ΔI q_map I q

[0092] 2. Define the torque interval ΔT e and I d Interval ΔI d By interpolation, I d I q With motor torque T eThe two-dimensional map between them is transformed into T. e I d with I q A two-dimensional map between them is obtained, thus yielding a given ΔT. e ΔI d The constant torque curve under intervals, such as Figure 2 This section shows the positive torque region. The cluster of curves represents the constant torque curves, where the minimum unit distance between different state points along the Id axis is ΔId, and the torque interval between the constant torque curves is ΔTe.

[0093] 3. On each constant torque curve, calculate the d-axis and q-axis currents I at different state points using the following formula. d I q The sum of squares is the magnitude of the current vector. The state points where the sum of squares is minimized on different constant torque curves are connected to form the MTPA calculation curve. This is represented as... Figure 2 The solid line shown is denoted as line L1. By fitting line L1, the MTPA fitting curve for the positive torque range is obtained, denoted as... Figure 2 The curve shown by the dashed line is denoted as line L.

[0094]

[0095] 4. Fit the different constant torque curves to obtain the corresponding curve equations. As the torque value increases, they are denoted as: Y1, Y2, Y3…Y… n …, the subscript n represents the nth constant torque curve during the torque increase process. Through mathematical calculation, the intersection points of the MTPA curve L with different constant torque curves are obtained, denoted as state points X1, X2, X3…X n ..., the subscript n represents the state point formed by the intersection of the nth constant torque curve and curve L, such as... Figure 6 As shown.

[0096] 5. Using each state point X1, X2, X3… as the center, successively draw circles with radii Δr, Δr*2, Δr*3… intersecting the corresponding isotor curves Y1, Y2, Y3… Here, we select the state points formed by the intersections in the region above the MTPA curve L, denoted as Xmn, where m represents the intersection point on the m-th isotor curve, and n represents the intersection point formed by the circle with radius n*Δr and the isotor curve, expressed as… Figure 7 .

[0097] 6. Connect the state points corresponding to the circular transaction points of the same radius on the family of equal torque curves in sequence to form a curve. For example, X 11 X 21 X 31 …forming curve L2,X12 X 22 X 32 …forming curve L3, X 13 X 23 X 33 …forming curve L4, and so on, lines L2, L3, and L4 are NVH optimization curves. As can be seen above, the state points represented by the intersections of lines L1, L2, L3, and L4 with each constant torque curve correspond to… The results increase sequentially. In this embodiment, three curves were selected as torque-current relationship curves in addition to the MTPA curve. The number of curves can be increased or decreased according to different electromagnetic schemes of the motor and different NVH optimization objectives, such as... Figure 8 As shown.

[0098] 7. Calibration process of the optimal NVH curve. Based on the calculated or calibrated maximum torque-current ratio (MTPA) curve L, compare the noise difference between the MTPA curve L and other calculated NVH optimization curves L2, L3, and L4 under the same torque command conditions. Then select the torque-current command curve with optimal NVH.

[0099] 8. Due to the current amplitude of the optimal NVH curve The values ​​are generally larger than the MTPA curve, which reduces the efficiency of the electric drive system. Therefore, in order to ensure a balance between the efficiency and NVH of the electric drive system, adjustments are made based on the optimal NVH curve. The MTPA curve L is adjusted so that the torque value on it changes from small to large (i.e., along the negative direction of the Id coordinate axis). d I q The corresponding state point is selected from the grouped curves obtained in step 7. Figure 9 This is represented as I increases when the torque increases. d I q The corresponding state points are first selected sequentially on lines L1, L2, L3, and L4, and then sequentially selected on lines L4, L3, L2, and L1. The resulting curve is represented as follows. Figure 9 As shown by line L'1, it can be seen that as the torque value increases, it first gradually moves away from L and then returns to L.

[0100] 9. Fit the line L'1 obtained in step 8 to obtain the MTPA correction curve, denoted as: Figure 10 The line L' in the diagram represents the constant torque region, and the state points on it correspond to the d-axis and q-axis current commands I for different torque commands. d__cmd I q__cmd .

[0101] Regarding steps 1-9, the following points need to be explained:

[0102] The above steps are explained using the positive torque region. The steps for handling the negative torque region are similar and will not be repeated here.

[0103] Steps 6-9 select the area above line L for MTPA curve correction. In fact, the same method can be used to obtain the MTPA curve correction result for the area below line L1.

[0104] The grouped curve results in step 8 are illustrated using lines L1, L2, L3, and L4. In practice, more grouped curves can be selected depending on different needs.

[0105] The innovation of this invention lies in:

[0106] 1. This solution can achieve both system efficiency and noise characteristics without increasing hardware costs, relying solely on software algorithm control.

[0107] 2. This solution uses the MTPA curve processing steps, which rely on existing motor control algorithms. The main parts of the algorithm can be shared with existing motor control algorithms.

[0108] The point of protection of this invention lies in the MTPA curve optimization step based on the noise optimization of the electric drive assembly.

[0109] Example 2

[0110] According to another aspect of the present invention, an AC motor current command generation apparatus is also provided. This apparatus can execute the AC motor current command generation method provided in Embodiment 1 above. The specific implementation and preferred application scenarios are the same as those in Embodiment 1 above, and will not be repeated here.

[0111] Figure 12 This is a schematic diagram of the structure of an AC motor current command generation device according to an embodiment of the present invention, as shown below. Figure 12 As shown, the device includes: an acquisition module 1202, used to acquire multiple sets of calibration data of an AC motor, wherein each set of calibration data includes direct-axis current, quadrature-axis current, motor torque, a two-dimensional mapping table, and a preset noise curve. The two-dimensional mapping table is used to characterize the mapping relationship between direct-axis current, quadrature-axis current, and motor torque, and the preset noise curve is used to characterize the maximum torque-current ratio control curve of the AC motor; a conversion module 1204, used to convert the multiple sets of calibration data using interpolation to obtain multiple equal torque curves, wherein the torque values ​​of the multiple equal torque curves are different; a determination module 1206, used to determine a target noise curve based on the multiple equal torque curves, direct-axis current, and quadrature-axis current; and a generation module 1208, used to generate a motor current command based on the target noise curve.

[0112] Optionally, the determining module includes: a first determining unit for determining the current vector magnitude based on the direct-axis current and the quadrature-axis current; a first processing unit for obtaining multiple noise curves based on the direct-axis current, the quadrature-axis current, and the current vector magnitude; and a second determining unit for determining the target noise curve based on multiple equal torque curves and multiple noise curves.

[0113] Optionally, the second determining unit includes: a first determining subunit, used to determine a first initial noise curve from multiple noise curves based on the preset noise curve; a second determining subunit, used to determine multiple first intersection points of multiple equal torque curves and multiple noise curves; and a third determining subunit, used to fit the first initial noise curve based on the multiple first intersection points to determine a target noise curve.

[0114] Optionally, the determining module further includes: a second processing unit for fitting multiple equal torque curves to obtain multiple curve equations, wherein the equal torque curves correspond one-to-one with the curve equations; a third processing unit for obtaining multiple noise curves based on the multiple curve equations and preset noise curves; a third determining unit for determining a second initial noise curve from the multiple noise curves based on the preset noise curves; and a fourth processing unit for fitting the second initial noise curve to obtain a target noise curve.

[0115] Optionally, the third processing unit includes: a fourth determining subunit, used to determine multiple second intersection points between multiple equal torque curves and a preset noise curve based on multiple curve equations; a fifth determining subunit, used to draw multiple circular curves based on a preset radius and with the multiple second intersection points as centers, and determine multiple third intersection points between the multiple circular curves and the equal torque curves corresponding to the circular curves; and a first processing subunit, used to obtain multiple noise curves based on the multiple third intersection points.

[0116] Optionally, the first processing subunit is further configured to: determine the third intersection point located above the preset noise curve as the fourth intersection point; and connect the fourth intersection points located on the same circular curve to obtain multiple noise curves.

[0117] Optionally, the first determining unit includes: a sixth determining subunit, used to determine the sum of the squares of the direct-axis current and the quadrature-axis current as the magnitude of the current vector.

[0118] Example 3

[0119] According to one aspect of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored program, wherein, when the program is running, the method for controlling the device where the computer-readable storage medium is located to perform any of the above-described methods is provided.

[0120] Example 4

[0121] According to another aspect of the present invention, a vehicle is also provided, including: a memory and a processor, the processor being configured to run a program stored in the memory, wherein the program, when running, performs any of the methods described above.

[0122] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0123] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0124] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0125] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0126] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0127] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0128] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for generating current commands for an AC motor, characterized in that, The method includes: Multiple sets of calibration data for the AC motor are obtained. Each set of calibration data includes direct-axis current, quadrature-axis current, motor torque, a two-dimensional mapping table, and a preset noise curve. The two-dimensional mapping table is used to characterize the mapping relationship between the direct-axis current, the quadrature-axis current, and the motor torque. The preset noise curve is used to characterize the maximum torque-current ratio control curve of the AC motor. The multiple sets of calibration data are converted using interpolation to obtain multiple equal torque curves, wherein the torque values ​​of the multiple equal torque curves are different. The target noise curve is determined based on the multiple equal torque curves, wherein the target noise curve is a correction curve of the optimal NVH curve, used to achieve a balance between the efficiency and NVH of the electric drive system. Based on the target noise curve, generate motor current commands; The determination of the target noise curve based on the multiple equal torque curves includes: determining the current vector amplitude based on the sum of the squares of the direct-axis current and the quadrature-axis current; sorting the current vector amplitudes corresponding to different state points on the multiple equal torque curves, and connecting the state points corresponding to different arrangement orders on the multiple equal torque curves to obtain multiple noise curves; determining the target noise curve based on the multiple equal torque curves and the multiple noise curves, wherein the target noise curve is obtained by fitting a first initial noise curve, and the first initial noise curve is the noise curve with optimal NVH among the multiple noise curves.

2. The method according to claim 1, characterized in that, Based on the multiple equal torque curves and the multiple noise curves, a target noise curve is determined, including: By comparing the noise difference between the preset noise curve and the multiple noise curves, the noise curve with the best NVH among the multiple noise curves is determined as the first initial noise curve; Determine multiple first intersection points of the multiple equal torque curves and the multiple noise curves; The target noise curve is determined by fitting the first initial noise curve based on the plurality of first intersection points.

3. The method according to claim 1, characterized in that, The target noise curve is determined based on the multiple equal torque curves, including: Determine multiple second intersection points between the multiple equal torque curves and the preset noise curve; Based on multiple preset radii, and drawing multiple circular curves with the multiple second intersection points as the center, determine multiple third intersection points between the multiple circular curves and the equal torque curves corresponding to the circular curves; Based on the multiple third intersection points, the multiple noise curves are obtained; By comparing the noise difference between the preset noise curve and the multiple noise curves, the noise curve with the best NVH among the multiple noise curves is determined as the second initial noise curve; The target noise curve is obtained by fitting the second initial noise curve.

4. The method according to claim 3, characterized in that, Based on the multiple third intersection points, the multiple noise curves are obtained, including: The third intersection point located above the preset noise curve is determined as the fourth intersection point; Connecting the fourth intersection point located on the same circular curve yields the multiple noise curves.

5. The method according to claim 3, characterized in that, Determining the current vector magnitude based on the direct-axis current and the quadrature-axis current includes: The sum of the squares of the direct-axis current and the quadrature-axis current is determined as the magnitude of the current vector.

6. A device for generating current commands for an AC motor, characterized in that, The device includes: The acquisition module is used to acquire multiple sets of calibration data of the AC motor. Each set of calibration data includes direct-axis current, quadrature-axis current, motor torque, two-dimensional mapping table and preset noise curve. The two-dimensional mapping table is used to characterize the mapping relationship between the direct-axis current, the quadrature-axis current and the motor torque. The preset noise curve is used to characterize the maximum torque-current ratio control curve of the AC motor. The conversion module is used to convert the multiple sets of calibration data using interpolation to obtain multiple equal torque curves, wherein the torque values ​​of the multiple equal torque curves are different. The determination module is used to determine the target noise curve based on the multiple equal torque curves, wherein the target noise curve is a correction curve of the optimal NVH curve, used to achieve a balance between the efficiency and NVH of the electric drive system; The generation module is used to generate motor current commands based on the target noise curve; The determining module is further configured to: determine the current vector amplitude based on the sum of the squares of the direct-axis current and the quadrature-axis current; sort the current vector amplitudes corresponding to different state points on the multiple equal torque curves; connect the state points corresponding to different arrangement orders on the multiple equal torque curves to obtain multiple noise curves; and determine a target noise curve based on the multiple equal torque curves and the multiple noise curves, wherein the target noise curve is obtained by fitting a first initial noise curve, and the first initial noise curve is the noise curve with optimal NVH among the multiple noise curves.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device on which the computer-readable storage medium is located to perform the method according to any one of claims 1 to 5.

8. A vehicle, characterized in that, include: A memory and a processor, the processor being configured to run a program stored in the memory, wherein the program, when executed, performs the method according to any one of claims 1 to 5.

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