A Method and Device for Optimizing the Trajectory of Active Zero-Frequency Crossing of a Speed-Sensorless Motor

Abstract

The present invention provides a method and device for optimizing the active zero-frequency ride-through trajectory of a speed sensorless motor, belonging to the field of motor control technology. The method comprises: determining a ramp angle for optimizing the original active zero-frequency ride-through trajectory; determining a change in excitation current based on the ramp angle and physical state parameters of the motor; and performing active zero-frequency ride-through of the motor based on the change in excitation current to optimize the original active zero-frequency ride-through trajectory. The method and device for optimizing the active zero-frequency ride-through trajectory of a speed sensorless motor provided by the present invention introduce a ramp angle to modify the operating point of existing methods during the active zero-frequency ride-through process, thereby eliminating or reducing the current and torque impacts that exist therein.

Description

Technical Field

[0001] The present invention relates to the field of motor control technology, and in particular to a method and device for optimizing the active zero-frequency crossing trajectory of a speed sensorless motor. Background Art

[0002] Sensorless induction motor control technology has gained widespread adoption due to its low cost, high reliability, and extended system maintenance cycles. Rotor position observation methods for sensorless induction motor vector control can be categorized into two main types: signal injection, which extracts rotor position information by sampling the response to the injected signal. Modeling, which uses a motor model to calculate rotor speed, is a more widely used approach in industry than signal injection.

[0003] By constructing an observer based on the mathematical model of the motor, it is possible to observe the rotor speed of an induction motor in real time. However, at extremely low stator current frequencies, speed observability is extremely weak, and speed observation methods based on the motor model are unable to estimate the rotor speed, resulting in unstable operation of the speed sensorless induction motor system. To address the speed observability issue at low frequencies, relevant literature has proposed a zero-frequency ride-through strategy based on excitation current adaptation.

[0004] However, the existing active zero-frequency ride-through method may cause current and torque impact problems during the active zero-frequency ride-through process. Summary of the Invention

[0005] The present invention provides a method and device for optimizing the trajectory of active zero-frequency ride-through of a speed sensorless motor, which are used to solve the defects of existing motor zero-frequency ride-through methods, thereby eliminating or reducing the current and torque impact during the active zero-frequency ride-through process.

[0006] In a first aspect, the present invention provides a method for optimizing the active zero-frequency crossing trajectory of a speed sensorless motor, comprising: determining a slope angle for optimizing the original active zero-frequency crossing trajectory; determining an excitation current change based on the slope angle and the physical state parameters of the motor; and performing active zero-frequency crossing of the motor based on the excitation current change to optimize the original active zero-frequency crossing trajectory.

[0007] According to the active zero-frequency crossing trajectory optimization method for a speed sensorless motor provided by the present invention, when the physical state parameters include the excitation current, the slip speed, and the rotor speed change, the excitation current change is determined according to the ramp angle and the physical state parameters of the motor. The corresponding solution formula is:

[0008]

[0009] Among them, Δi sdIndicates the change in excitation current, i sd represents the excitation current, γ represents the slope angle, ω s Indicates the slip speed, Δω r Indicates the change in rotor speed.

[0010] The method for optimizing the active zero-frequency crossing trajectory of a speed sensorless motor provided by the present invention further includes: when the slope angle is less than a preset angle value, simplifying the solution formula to obtain a simplified target solution formula; the target solution formula is specifically:

[0011]

[0012] According to the active zero-frequency crossing trajectory optimization method for a speed sensorless motor provided by the present invention, the preset angle value is π / 12.

[0013] In a second aspect, the present invention further provides a speed sensorless motor active zero-frequency crossing trajectory optimization device, comprising: a ramp angle determination module, an excitation current variation determination module, and an active zero-frequency crossing module;

[0014] The ramp angle determination module is used to determine the ramp angle for optimizing the original active zero-frequency crossing trajectory;

[0015] The excitation current variation determination module is used to determine the excitation current variation according to the ramp angle and the physical state parameters of the motor;

[0016] The active zero-frequency ride-through module is used to perform active zero-frequency ride-through of the motor according to the variation of the excitation current, so as to optimize the original active zero-frequency ride-through trajectory.

[0017] According to the speed sensorless motor active zero-frequency crossing trajectory optimization device provided by the present invention, when the physical state parameters include the excitation current, the slip speed, and the rotor speed change, the excitation current change is determined according to the ramp angle and the physical state parameters of the motor, and the corresponding solution formula is:

[0018]

[0019] Among them, Δi sd Indicates the change in excitation current, i sd represents the excitation current, γ represents the slope angle, ω s Indicates the slip speed, Δω r Indicates the change in rotor speed.

[0020] According to the speed sensorless motor active zero-frequency crossing trajectory optimization device provided by the present invention, the device further includes: a solution formula simplification module;

[0021] The solution formula simplification module is used to simplify the solution formula when the slope angle is less than a preset angle value to obtain a simplified target solution formula;

[0022] The target solution formula is specifically:

[0023]

[0024] According to the speed sensorless motor active zero-frequency crossing trajectory optimization device provided by the present invention, the preset angle value is π / 12.

[0025] In a third aspect, the present invention further provides an asynchronous motor, which is controlled by applying the steps of the active zero-frequency crossing trajectory optimization method for a speed sensorless motor as described in any of the above items.

[0026] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the active zero-frequency crossing trajectory optimization method for a speed sensorless motor as described in any one of the above.

[0027] The present invention provides a method and device for optimizing the trajectory of active zero-frequency crossing of a speed sensorless motor. By introducing a ramp angle, the operating point of the existing method during the active zero-frequency crossing process is corrected, thereby eliminating or weakening the current and torque impacts. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 Schematic diagram of the trajectory of the existing active zero-frequency ride-through method provided by the present invention;

[0030] Figure 2 1. It is a flow chart of the method for optimizing the active zero-frequency crossing trajectory of a speed sensorless motor provided by the present invention;

[0031] Figure 3 Schematic diagram of the trajectory of the active zero-frequency crossing trajectory optimization method of the speed sensorless motor provided by the present invention;

[0032] Figure 4 1 is a schematic diagram of test results of the existing active zero-frequency ride-through method provided by the present invention;

[0033] Figure 5It is a schematic diagram of the test results of the active zero-frequency crossing trajectory optimization method of the speed sensorless motor provided by the present invention. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0035] It should be noted that, in the description of the embodiments of the present invention, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising 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 apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0036] In order to more clearly illustrate the technical solution of the present invention, the problem of speed observability, the principles and defects of the prior art are briefly described below.

[0037] The unobservability of the rotor speed and flux position of a sensorless induction motor under steady-state conditions with zero stator frequency is a problem. This can be intuitively understood as the lack of electromagnetic induction on the rotor side when the input voltage and current on the stator side of the induction motor are DC, making it impossible to extract rotor position information from the electrical signal. The following briefly describes the development of a full-order observer model for an induction motor and the speed observation method related to the present invention.

[0038] Referring to the T-type equivalent model of the induction motor in the two-phase stationary α-β coordinate system, the stator current and rotor flux are selected as state variables. The mathematical model of the induction motor can be expressed as follows:

[0039]

[0040] In formula (1), i s =[i αs i βs ] T ,λ r =[λ αr λ βr ] T ,u s =[u αs uβs ] T They are the stator current, rotor flux and stator voltage in the two-phase stationary α-β coordinate system respectively.

[0041] Among them, A 11 =aI,A 12 =cI-cT r ω r J, A 21 =dI,A 22 =-I / T r +ω r J, B = [b 0] T ;

[0042]

[0043] R s is the stator resistance of the induction motor, R r is the induction motor rotor resistance, L s is the stator inductance of the induction motor, L r is the induction motor rotor inductance, L m is the mutual inductance of the induction motor, and σ is the leakage inductance coefficient.

[0044] According to the above-mentioned mathematical model of induction motor (1), the rotor speed is selected as the observed variable, and the state equation of the induction motor full-order observer is:

[0045]

[0046] Where, and is a coefficient matrix, where the rotor speed ω r Replaced by observing the rotor speed

[0047] According to the mathematical model of the induction motor (1) and the observer state equation (2), the observer error equation can be obtained as follows:

[0048]

[0049] Where, ΔA 12 =-cT r Δω r J, ΔA 22 =Δω r J.

[0050] Based on the observer error equation and the Popov stability theorem, the adaptive rate of speed identification can be derived.

[0051] The observer speed adaptation rate can be expressed as:

[0052]

[0053] Among them, K pω , K iω is the adjustable PI parameter of the stator resistance observer; p is the differential operator.

[0054] In the two-phase stationary α-β coordinate system, the synchronous speed and slip speed can be expressed as:

[0055]

[0056] Among them, ω e is the synchronous speed, ω s is the slip speed; i sd is the excitation current, i sq is the torque current, T r represents the rotor time constant.

[0057] Electromagnetic torque T e It can be expressed as:

[0058] T e =K e i sd i sq (6)

[0059] Among them, K e is the torque coefficient, and n p Indicates the number of pole pairs of the induction motor.

[0060] From Equation (5), we can see that when the excitation current is constant, the slip speed is linearly related to the torque current. Therefore, we can change the slip speed while maintaining a constant electromagnetic torque by adjusting the excitation current set value, thereby maintaining a minimum synchronous speed and ensuring speed observability.

[0061] The excitation current command value is expressed as:

[0062]

[0063] in, Indicates the excitation current command value after adjusting the excitation current. Indicates the excitation current command value before adjusting the excitation current. Indicates the amount of change in the excitation current used to adjust the excitation current command value.

[0064] The existing technology can change the synchronous speed by calculating the change in excitation current to maintain the minimum observable boundary.

[0065] Figure 1This is a schematic diagram of the trajectory of the existing active zero-frequency crossing method provided by the present invention. Figure 1 Taking the working condition as an example, a brief description is given. Figure 1 A0 to A7 in the chart are different motor operating conditions. Indicates the synchronous speed limit value.

[0066] Under load conditions, the induction motor's speed gradually decreases to zero, then reverses, increasing the speed. The motor's operating point moves from A0 to A1, then along the dotted line to A7, and then A7 to A8. However, under conditions where the speed changes slowly, the process from A1 to A7 cannot be completed.

[0067] like Figure 1 As shown in FIG, if the zero-frequency crossing method based on excitation current adaptation (i.e., the existing technology) is adopted, the motor rotor speed gradually decreases (the motor speed acceleration is extremely low, simulating the steady-state working condition), and the motor operating condition point gradually approaches the stator zero-frequency line (ω e =0), after crossing the stator zero frequency line, the motor enters the low-speed power generation area and finally leaves the low-speed power generation unstable area, and the motor maintains power generation operation.

[0068] From A1 to A3, when the synchronous speed reaches the limit, the excitation current setpoint gradually decreases, increasing the motor slip speed and thus maintaining the induction motor's operating point convergence to the synchronous speed limit. The motor instantaneously completes the stator zero-frequency line crossing between A3 and A5.

[0069] From A5 to A7, when the synchronous speed reaches the limit value, the excitation current set value returns to the initial value, and the motor slip speed will increase, thereby maintaining the induction motor operating condition point at the synchronous speed limit value.

[0070] The sensorless induction motor successfully completes the low-frequency ride-through process, and the speed is observable throughout the entire process. However, the active zero-frequency ride-through method provided by the above-mentioned prior art can cause current and torque shock during the transition from A3 to A5 during zero-frequency ride-through.

[0071] The technical solution of the present invention is proposed just for the current shock and torque shock caused by the above-mentioned transient ride-through.

[0072] Next, combine Figure 2-Figure 5 The present invention provides a method and device for optimizing the active zero-frequency crossing trajectory of a speed sensorless motor.

[0073] The technical solution of the present invention is proposed to solve the current shock and torque shock caused by the above-mentioned transient ride-through. Figure 2-Figure 5 The present invention provides a method and device for optimizing the active zero-frequency crossing trajectory of a speed sensorless motor.

[0074] Figure 2 FIG. 1 is a flow chart of the method for optimizing the active zero-frequency crossing trajectory of a speed sensorless motor provided by the present invention. Figure 2 As shown, including but not limited to the following steps:

[0075] Step 201: Determine a slope angle for optimizing an original active zero-frequency crossing trajectory.

[0076] Figure 3 Schematic diagram of the trajectory of the active zero-frequency crossing trajectory optimization method of the speed sensorless motor provided by the present invention, such as Figure 3 As shown, Figure 3 The optimized active zero-frequency ride-through trajectory of the present invention is shown, that is, the optimized active zero-frequency ride-through trajectory of the induction motor.

[0077] like Figure 3 As shown, by introducing the slope angle γ, the present invention can modify the traditional A3-A5-A7 trajectory (i.e. the original active zero-frequency crossing trajectory) to A3-N-A7 (i.e. Figure 3 The gradient trajectory is shown in FIG, which can be understood as the optimized active zero-frequency crossing trajectory).

[0078] It can be understood that the main idea of the present invention is to eliminate the torque and current impact of active zero-frequency ride-through by designing a suitable ramp angle γ.

[0079] Optionally, γ=π / 18.

[0080] Step 202: Determine the excitation current variation according to the ramp angle and the physical state parameters of the motor.

[0081] Optionally, the physical state parameters may include operating parameters of the motor and its own physical parameters. That is, the present invention characterizes the excitation current variation by pre-set ramp angle γ and physical state parameters to facilitate adjustment of the excitation current and further optimize the original active zero-frequency crossing trajectory.

[0082] Step 203: performing active zero-frequency ride-through of the motor according to the variation of the excitation current to optimize the original active zero-frequency ride-through trajectory.

[0083] Referring to formula (7) provided in the above-mentioned prior art, the synchronous speed is changed by adjusting the variation of the excitation current, the minimum observable boundary is maintained, and active zero-frequency crossing of the motor is performed.

[0084] The present invention introduces a ramp angle to modify the operating point of the existing method during the active zero-frequency ride-through process, thereby eliminating or weakening the current and torque impacts.

[0085] As an optional embodiment, the derivation process for determining the variation of the excitation current is described below.

[0086] like Figure 3 As shown, the length of A3-A5 is the synchronous speed limit value, which is expressed as:

[0087]

[0088] in, Indicates the slip speed at operating point A3, Indicates the slip speed at operating point A5.

[0089] For triangle A3-N-A5, according to the sine theorem, each side must satisfy:

[0090]

[0091] Therefore, the length of A3-N can be solved as:

[0092]

[0093] Furthermore, for triangle A3-MN, the two right-angled sides represent the changes in rotor speed and slip speed, respectively, which can be expressed as:

[0094]

[0095] Among them, Δω r Indicates the change in rotor speed, Δω s Indicates the change in slip speed.

[0096] like Figure 3 As shown in Figure 2, the slope of the optimized active zero-frequency crossing trajectory is -tanγ. If the trajectory is a straight line, then:

[0097]

[0098] In the present invention, under constant load conditions, the slip speed of the induction motor is affected by the change of the excitation current, so there exists:

[0099]

[0100] According to the above formula, we can get:

[0101]

[0102] Combining equations (12) and (14), we can obtain:

[0103]

[0104] From the above formula, it can be found that the rate of change of the rotational speed directly affects the rate of change of the excitation current in the zero-frequency ride-through method based on excitation current adaptation. However, the ramp angle γ introduced in the present invention can correct the rate of change of the excitation current. In the control system, since the sampling time is very short, the excitation current and rotor speed change very little within a sampling period. According to the above formula (15), the excitation current change within the sampling period can be obtained as:

[0105]

[0106] Based on the contents of the above embodiment, as an optional embodiment, the present invention provides a method for optimizing the trajectory of active zero-frequency crossing of a speed sensorless motor. When the physical state parameters include the excitation current, the slip speed, and the rotor speed variation, the above formulas (5), (6), and (16) are used to obtain the solution formula for the excitation current variation:

[0107]

[0108] Furthermore, when the slope angle is less than the preset angle value, the slope angle γ and its tangent value are not much different. Based on this, the solution formula is simplified to obtain the simplified target solution formula, which is specifically:

[0109]

[0110] The preset angle value may be π / 12.

[0111] To verify the effectiveness of the above-mentioned implementation scheme provided by the present invention, a 2.2kW induction motor was used to conduct an experimental demonstration on the towing platform. A comparative experiment was conducted between the existing zero-frequency ride-through method and the speed sensorless motor active zero-frequency ride-through trajectory optimization method provided by the present invention.

[0112] Figure 4 Schematic diagram of the test results of the existing active zero-frequency ride-through method provided by the present invention. Figure 5 Schematic diagram of the test results of the active zero-frequency crossing trajectory optimization method for the speed sensorless motor provided by the present invention, as shown in FIG. Figure 4 and Figure 5 As shown in the figure, the waveforms of estimated speed, synchronous speed, estimated rotor flux, dq current, stator current amplitude, electromagnetic torque and phase current are shown from top to bottom. Figure 4 In the example, the travel time is set to 25s from 25rpm to -100rpm and 30s from 25rpm to -125rpm, which means the acceleration is -0.083r / s2. The load is set to 10Nm.

[0113] The traditional method corrects the synchronous speed by adaptively changing the excitation current, achieving speed observability at low synchronous speed. With the step change of the magnetizing current, the active zero-frequency ride-through is completed quickly, generating current and speed ripples. Figure 4 As shown in the figure, the torque current ripple is as high as 0.61A, or 8.8% of the rated current. The stator current amplitude ripple is 1.67A, or 41.8% of the stator current. In addition, the electromagnetic torque fluctuation reaches 9.91Nm, or 99% of the applied load. The fluctuations in the estimated speed and synchronous speed are 47.4rpm and 12.6rpm, respectively.

[0114] like Figure 5 As shown, during active zero-frequency ride-through, the changes in synchronous speed, torque current, and electromagnetic torque are smoother due to the ramp angles provided in the present invention. Specifically, synchronous speed fluctuations are eliminated. Simultaneously, the estimated speed fluctuation is reduced to 28.4 rpm. The torque current ripple is reduced to 0.52 A, or 7.5% of the rated current. The stator current amplitude is reduced, with the ripple reduced to 0.76 A, approximately 19% of the stator current. The electromagnetic torque fluctuation is 5.71 Nm, or approximately 57% of the applied load.

[0115] The above experimental results show that the speed sensorless motor active zero-frequency crossing trajectory optimization method provided by the present invention can effectively reduce the ripple in the existing (traditional) active zero-frequency crossing process, that is, it can achieve the beneficial effect of eliminating or weakening the existing current and torque impact.

[0116] The present invention also provides a speed sensorless motor active zero-frequency ride-through trajectory optimization device, comprising: a ramp angle determination module, an excitation current variation determination module and an active zero-frequency ride-through module;

[0117] The ramp angle determination module is used to determine the ramp angle for optimizing the original active zero-frequency crossing trajectory;

[0118] The excitation current variation determination module is used to determine the excitation current variation according to the ramp angle and the physical state parameters of the motor;

[0119] The active zero-frequency ride-through module is used to perform active zero-frequency ride-through of the motor according to the variation of the excitation current, so as to optimize the original active zero-frequency ride-through trajectory.

[0120] According to the speed sensorless motor active zero-frequency crossing trajectory optimization device provided by the present invention, when the physical state parameters include the excitation current, the slip speed, and the rotor speed change, the excitation current change is determined according to the ramp angle and the physical state parameters of the motor, and the corresponding solution formula is:

[0121]

[0122] Among them, Δi sd Indicates the change in excitation current, i sd represents the excitation current, γ represents the slope angle, ω s Indicates the slip speed, Δω r Indicates the change in rotor speed.

[0123] According to the speed sensorless motor active zero-frequency crossing trajectory optimization device provided by the present invention, the device further includes: a solution formula simplification module;

[0124] The solution formula simplification module is used to simplify the solution formula when the slope angle is less than a preset angle value to obtain a simplified target solution formula;

[0125] The target solution formula is specifically:

[0126]

[0127] According to the speed sensorless motor active zero-frequency crossing trajectory optimization device provided by the present invention, the preset angle value is π / 12.

[0128] It should be noted that the speed sensorless motor active zero-frequency crossing trajectory optimization device provided in an embodiment of the present invention can execute the speed sensorless motor active zero-frequency crossing trajectory optimization method described in any of the above embodiments during specific operation, which will not be described in detail in this embodiment.

[0129] The present invention also provides an asynchronous motor, which is controlled by applying the steps of the speed sensorless motor active zero-frequency crossing trajectory optimization method as described in any of the above items, the method comprising: determining a ramp angle for optimizing the original active zero-frequency crossing trajectory; determining an excitation current change based on the ramp angle and the physical state parameters of the motor; and performing active zero-frequency crossing of the motor based on the excitation current change to optimize the original active zero-frequency crossing trajectory.

[0130] On the other hand, the present invention also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the speed sensorless motor active zero-frequency crossing trajectory optimization method provided by the above-mentioned embodiments, the method including: determining a ramp angle for optimizing the original active zero-frequency crossing trajectory; determining an excitation current change based on the ramp angle and the physical state parameters of the motor; and performing active zero-frequency crossing of the motor based on the excitation current change to optimize the original active zero-frequency crossing trajectory.

[0131] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it is implemented to perform the active zero-frequency crossing trajectory optimization method of a speed sensorless motor provided in the above-mentioned embodiments. The method includes: determining a ramp angle for optimizing the original active zero-frequency crossing trajectory; determining an excitation current change based on the ramp angle and the physical state parameters of the motor; and performing active zero-frequency crossing of the motor based on the excitation current change to optimize the original active zero-frequency crossing trajectory.

[0132] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0133] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for optimizing the trajectory of a speed sensorless motor with active zero-frequency crossing, characterized in that: include: Determining a slope angle for optimizing the original active zero-frequency crossing trajectory; Determining a change in excitation current according to the ramp angle and physical state parameters of the motor; Performing active zero-frequency ride-through of the motor according to the variation of the excitation current to optimize the original active zero-frequency ride-through trajectory; In the case where the physical state parameters include the excitation current, the slip speed, and the rotor speed variation, the excitation current variation is determined according to the ramp angle and the physical state parameters of the motor. The corresponding solution formula is: Among them, Δi sd Indicates the change in excitation current, i sd represents the excitation current, γ represents the slope angle, ω s Indicates the slip speed, Δω r Indicates the change in rotor speed; The method further includes simplifying the solution formula to obtain a simplified target solution formula when the slope angle is less than a preset angle value; the target solution formula is specifically:

2. The method for optimizing the active zero-frequency crossing trajectory of a speed sensorless motor according to claim 1, characterized in that: The preset angle value is π / 12.

3. A speed sensorless motor active zero-frequency crossing trajectory optimization device, characterized in that: include: Slope angle determination module, excitation current variation determination module and active zero frequency ride-through module; The ramp angle determination module is used to determine the ramp angle for optimizing the original active zero-frequency crossing trajectory; The excitation current variation determination module is used to determine the excitation current variation according to the ramp angle and the physical state parameters of the motor; In the case where the physical state parameters include the excitation current, the slip speed, and the rotor speed variation, the excitation current variation is determined according to the ramp angle and the physical state parameters of the motor. The corresponding solution formula is: Among them, Δi sd Indicates the change in excitation current, i sd represents the excitation current, γ represents the slope angle, ω s Indicates the slip speed, Δω r Indicates the change in rotor speed; The active zero-frequency ride-through module is used to perform active zero-frequency ride-through of the motor according to the variation of the excitation current, so as to optimize the original active zero-frequency ride-through trajectory; The device further comprises: a formula simplification module; The solution formula simplification module is used to simplify the solution formula when the slope angle is less than a preset angle value to obtain a simplified target solution formula; The target solution formula is specifically:

4. The speed sensorless motor active zero-frequency crossing trajectory optimization device according to claim 3, characterized in that: The preset angle value is π / 12.

5. An asynchronous motor, characterized in that: The asynchronous motor is controlled by applying the steps of the active zero-frequency crossing trajectory optimization method for a speed sensorless motor as described in any one of claims 1 to 2.

6. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the active zero-frequency crossing trajectory optimization method for a speed sensorless motor are implemented as described in any one of claims 1 to 2.

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