Current verification method and device, three-phase electric drive system and storage medium

Abstract

The invention provides a current verification method and device, a three-phase electric drive system and a storage medium, and relates to the technical field of motor control. The method comprises the following steps: sampling a two-phase current signal in a three-phase electric drive system according to a preset sampling period, and converting the sampled two-phase current signal into a two-axis current component under a two-phase coordinate system; determining a current fundamental frequency based on the two-axis current component, and generating a two-axis current combination characteristic quantity based on the two-axis current component; and extracting a current ripple component of the two-axis current combination characteristic quantity at the target frequency, and determining a current verification result of the three-phase electric drive system based on the current ripple component. The current rationality of the three-phase electric drive system is indirectly evaluated through the two-phase current signal, the reliability of the current verification result is ensured, and a three-phase current detection device is replaced with the two-phase current detection device. The detection cost is reduced in multiple aspects, the hardware random failure rate is reduced, and the reliability of current rationality verification is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular, to a current verification method, device, three-phase electric drive system, and storage medium. Background Art

[0002] In the era of rapid development of new energy technologies today, the electric drive system, as the core power unit of many electric devices, has become increasingly important. Taking electric vehicles as an example, the three-phase electric drive system is like the "heart" of the vehicle, responsible for efficiently converting electrical energy into mechanical energy to drive the vehicle. And the current signal, as the main parameter of the three-phase motor drive, directly affects the reliability of the three-phase electric drive system.

[0003] In related technologies, in order to ensure the reliability of current verification in the three-phase electric drive system, the verification methods adopted at present are often relatively complex, with obvious limitations such as high detection costs. Summary of the Invention

[0004] The problem solved by the present invention is how to ensure the reliability of current verification while reducing the detection cost.

[0005] To solve the above problems, the present invention provides a current verification method, including:

[0006] Sampling two-phase current signals in the three-phase electric drive system according to a preset sampling period, and converting the sampled two-phase current signals into two-axis current components in a two-phase coordinate system;

[0007] Determining a current fundamental frequency based on the two-axis current components, and generating a two-axis current combined feature quantity based on the two-axis current components;

[0008] Extracting a current ripple component of the two-axis current combined feature quantity at a target frequency, and determining a current verification result of the three-phase electric drive system based on the current ripple component; wherein, the target frequency is determined based on the current fundamental frequency.

[0009] Optionally, the determining a current fundamental frequency based on the two-axis current components includes:

[0010] Performing an arctangent process on the two-axis current components to obtain the electrical angle of the two-phase current signals;

[0011] Determining the current fundamental frequency according to the change rate of the electrical angle.

[0012] Optionally, before the determining the current fundamental frequency according to the change rate of the electrical angle, it further includes:

[0013] Obtain a plurality of the two-phase current signals obtained by sampling, and arrange the corresponding electrical angles according to the sampling order of each of the two-phase current signals to obtain an electrical angle sequence;

[0014] Obtain the differences between each of the electrical angles and a target electrical angle to obtain a plurality of electrical angle differences; wherein, the target electrical angle includes the electrical angle that is a preset interval away from the electrical angle in the electrical angle sequence;

[0015] Obtain the change rate of the electrical angle according to the ratio of the sum of each of the electrical angle differences to a target period; wherein, the target period is determined based on the preset sampling period, the preset interval, and the number of the electrical angle differences.

[0016] Optionally, the two-axis current combined feature quantity includes a two-axis vector combined current obtained by vector synthesis of the two-axis current components; the target frequency includes twice the current fundamental frequency.

[0017] Optionally, the extracting the current ripple component of the two-axis current combined feature quantity at the target frequency includes:

[0018] Perform orthogonal decomposition on the two-axis vector combined current at twice the current fundamental frequency to obtain a sine projection component and a cosine projection component of the two-axis vector combined current in the frequency domain;

[0019] Based on the sine projection component and the cosine projection component, obtain the current ripple component; wherein, the real part of the current ripple component is determined based on the cosine projection component, and the imaginary part of the current ripple component is determined based on the sine projection component.

[0020] Optionally, the determining the current verification result of the three-phase electric drive system based on the current ripple component includes:

[0021] Determine the ratio between a first average amplitude and a second average amplitude to obtain a target ratio; wherein, the first average amplitude includes the average amplitudes corresponding to a plurality of the current ripple components; the second average amplitude includes the average amplitudes corresponding to a plurality of the two-axis vector combined currents;

[0022] When the target ratio is greater than a preset threshold, the current verification result is that the verification fails.

[0023] Optionally, before the determining the current fundamental frequency based on the two-axis current components, it further includes:

[0024] Judge whether the two-phase current signals meet a preset verification condition; wherein, the preset verification condition includes: the sampling quantity corresponding to the two-phase current signals is greater than a preset quantity, and / or, the sampling duration corresponding to the two-phase current signals is greater than a preset duration;

[0025] If so, determine the current fundamental frequency based on the two-axis current components;

[0026] If not, return to the step of sampling the two-phase current signals in the three-phase electric drive system according to the preset sampling period.

[0027] In the present invention, sampling the two-phase current signals in the three-phase electric drive system according to the preset sampling period is conducive to grasping the actual situation of the current in the three-phase electric drive system and providing a basic data basis for subsequent current rationality verification. On this basis, the present invention assumes that when the three-phase currents have no amplitude error and phase error and satisfy the symmetry condition, the third-phase current signal can be represented by a specific relationship of the two-phase current signals. At this time, coordinate transformation can be performed only based on the two-phase current signals, and then the two-phase current signals in the three-phase electric drive system are converted into two-axis current components in the two-phase coordinate system, without collecting all three-phase current signals, thereby reducing the number of current detection devices and saving hardware costs. It is also not necessary to calculate the third-phase current signal based on the two-phase current signals, which is conducive to simplifying data processing and reducing computing power consumption, thereby reducing detection costs in multiple aspects. In the present invention, determining the current fundamental frequency based on the two-axis current components can improve the accuracy of the current fundamental frequency and provide a reference basis for subsequent extraction of the current ripple component. The two-axis current combination feature quantity generated based on the two-axis current components can reflect the cooperative relationship between the two-axis current components, which is conducive to subsequent identification of whether there are errors such as current amplitude and phase by extracting the current ripple component from the two-axis current combination feature quantity, thereby reducing the difficulty of current rationality verification. At the same time, since the two-axis current combination feature quantity in the present invention is generated based on the two-axis current components, the fundamental frequency corresponding to the two-axis current combination feature quantity is determined by the current fundamental frequency, and the target frequency when extracting the current ripple amplitude is also determined based on the current fundamental frequency. Therefore, by extracting the current ripple component of the two-axis current combination feature quantity at the target frequency in the present invention, the fluctuation characteristics of the current can be accurately and effectively extracted. When there are no amplitude error and phase error in the three-phase currents of the three-phase electric drive system, the amplitude of the two-axis current combination feature quantity should be a constant value and theoretically no current ripple component will be generated. Thus, the current ripple component extracted from the two-axis current combination feature quantity at the target frequency in the present invention can reflect the actual situation of the amplitude error and / or phase error of the three-phase currents, and thus determine the current verification result of the three-phase electric drive system based on the current ripple component. In this way, the present invention can indirectly evaluate the current rationality of the three-phase electric drive system by collecting two-phase current signals, ensure the reliability of the current verification result, and further can realize the replacement of the three-phase current detection device with the two-phase current detection device. Compared with the method of collecting three-phase currents for current rationality verification, the present invention reduces detection costs in multiple aspects and is also conducive to reducing the hardware random failure rate and further improving the reliability of current rationality verification.

[0028] The present invention also provides a current verification device, including:

[0029] A sampling module, configured to sample two-phase current signals in a three-phase electric drive system according to a preset sampling period, and convert the sampled two-phase current signals into two-axis current components in a two-phase coordinate system;

[0030] A determination module, configured to determine a current fundamental frequency based on the two-axis current components, and generate a two-axis current combined feature quantity based on the two-axis current components;

[0031] A verification module, configured to extract a current ripple component of the two-axis current combined feature quantity at a target frequency, and determine a current verification result of the three-phase electric drive system based on the current ripple component; wherein, the target frequency is determined based on the current fundamental frequency.

[0032] The current verification device provided by the present invention and the current verification method have basically the same advantages compared with the prior art, and will not be elaborated here.

[0033] The present invention also provides a three-phase electric drive system, including a memory and a processor;

[0034] The memory is used for storing a computer program;

[0035] The processor is configured to implement the current verification method as described above when executing the computer program.

[0036] The three-phase electric drive system provided by the present invention and the current verification method have basically the same advantages compared with the prior art, and will not be elaborated here.

[0037] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the current verification method as described above is implemented.

[0038] The computer-readable storage medium provided by the present invention and the current verification method have basically the same advantages compared with the prior art, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic flow chart of the current verification method according to an embodiment of the present invention;

[0040] Figure 2 is a schematic structural diagram of the current verification device according to an embodiment of the present invention;

[0041] Figure 3 is a schematic structural diagram of the three-phase electric drive system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of specific embodiments of the present invention with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. Instead, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0043] It should be understood that the various steps described in the method embodiments of the present invention can be executed in different orders and / or executed in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this regard.

[0044] The term "including" and its variations used herein are open-ended, that is, "including but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish different devices, modules, or units, and are not used to limit the order of functions performed by these devices, modules, or units or their interdependent relationships.

[0045] It should be noted that the modifications of "one" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly specified in the context, it should be understood as "one or more".

[0046] In the related art, a three-phase current sensor can be used to measure the three-phase current signals of a three-phase electric drive system and perform safety verification based on the three-phase current signals. However, the resulting random hardware failure rate and data processing volume also increase accordingly, which not only affects the reliability of the current verification results but also leads to high hardware costs of the three-phase electric drive system and high computing power overhead required for current verification.

[0047] As Figure 1 shown, a current verification method provided by an embodiment of the present invention includes the following steps:

[0048] S1: Sample the two-phase current signals in the three-phase electric drive system according to a preset sampling period, and convert the sampled two-phase current signals into two-axis current components in a two-phase coordinate system.

[0049] Specifically, the three-phase electric drive system referred to in this embodiment represents a system with a three-phase motor as the driving device, and any two-phase current signals in the three-phase electric drive system can be sampled according to a preset sampling period (such as 2 microseconds). For example, the U-phase current signal and the V-phase current signal can be collected every 2 microseconds through two pre-set current sensors, and then two-phase current signals can be obtained.

[0050] In one embodiment, the two-phase current signals include a first-phase current signal (such as the U-phase current signal) and a second-phase current signal (such as the V-phase current signal). Assuming that there are no amplitude and phase errors in the three-phase currents and they satisfy the symmetry condition (i.e., I u +I v +I w = 0), the third-phase current signal can be indirectly represented based on the first-phase current signal and the second-phase current signal. At this time, the Clarke Transformation can be simplified, so that without collecting or deriving the third-phase current signal, the two-phase current signals in the three-phase coordinate system can be converted into two-axis current components in the two-phase coordinate system, and the two-axis current components satisfy:

[0051]

[0052] Wherein, I u represents the first-phase current signal in the two-phase current signals; I v represents the second-phase current signal in the two-phase current signals; I α represents the α-axis component in the two-axis current components; I β represents the β-axis current component in the two-axis current components; the two-phase coordinate system referred to in this embodiment is the two-phase stationary coordinate system composed of the α-axis and the β-axis.

[0053] In this embodiment, sampling the two-phase current signals in the three-phase electric drive system according to the preset sampling period is beneficial to mastering the actual situation of the current in the three-phase electric drive system and providing a basic data basis for subsequent current rationality verification. On this basis, assuming that the three-phase currents have no amplitude and phase errors and satisfy the symmetry condition, the third-phase current signal can be represented by the specific relationship of the two-phase current signals. At this time, the coordinate transformation can be performed only based on the two-phase current signals, and then the two-phase current signals in the three-phase electric drive system can be converted into two-axis current components in the two-phase coordinate system, without collecting all three-phase current signals, thus reducing the number of current detection devices and saving hardware costs. There is also no need to calculate the third-phase current signal based on the two-phase current signals, simplifying data processing and reducing computing power overhead. While reducing the detection cost in many aspects, it is also beneficial to reducing the reliability of the current rationality verification affected by the hardware random failure rate.

[0054] S2: Determine the fundamental current frequency based on the two-axis current components, and generate a two-axis current combined feature quantity based on the two-axis current components.

[0055] Specifically, after the coordinate transformation of the collected two-phase current signals to obtain the two-axis current components, the fundamental current frequency can be determined according to the two-axis current components. For example, the fast Fourier transform can be performed on multiple two-axis current component signals collected, converting the time-domain signal into a frequency-domain signal. In the frequency domain, the fundamental frequency component will have obvious peaks at the corresponding frequency positions. By determining the frequency where the peak is located, the fundamental current frequency can be determined. The two-axis current combined feature quantity referred to in this embodiment represents a feature quantity determined based on the combination of two-axis current components, such as the amplitude ratio of the two-axis current components, the vector synthesis current corresponding to the two-axis current components, etc.

[0056] In this embodiment, determining the fundamental current frequency based on the two-axis current components can improve the accuracy of the fundamental current frequency, providing a reference basis for the subsequent extraction of the current ripple component. And the two-axis current combined feature quantity generated based on the two-axis current components can reflect the cooperative relationship between the two-axis current components, which is beneficial to subsequent identification of whether there are current amplitude errors or phase errors through the current ripple component extracted from the two-axis current combined feature quantity, thereby reducing the difficulty of current rationality verification.

[0057] S3: Extract the current ripple component of the two-axis current combined feature quantity at the target frequency, and determine the current verification result of the three-phase electric drive system based on the current ripple component; wherein, the target frequency is determined based on the fundamental current frequency.

[0058] Specifically, the current ripple component referred to in this embodiment represents the periodic fluctuation component existing in the current signal due to current amplitude or phase deviation in the three-phase electric drive system. Since the two-axis current combined feature quantity is determined based on the two-axis current components, the fundamental frequency of the two-axis current combined feature quantity in this embodiment is determined by the fundamental current frequency. And the target frequency is determined based on the fundamental current frequency, such as a preset multiple (such as twice) of the fundamental current frequency. Therefore, extracting the current ripple component of the two-axis current combined feature quantity at the target frequency (such as based on a band-pass filter with the center frequency being the target frequency) can accurately extract the fluctuation characteristics of the current, and then determine the current verification result of the three-phase electric drive system. For example, the amplitude of the current ripple component can be obtained and compared with a preset amplitude threshold. When the amplitude of the current ripple component is greater than the preset amplitude threshold, it indicates that there may be large amplitude or phase errors in the three-phase currents in the three-phase electric drive system, and the current verification result of the three-phase electric drive system is that the verification fails.

[0059] In this embodiment, sampling the two-phase current signals in the three-phase electric drive system according to a preset sampling period is beneficial to grasping the actual situation of the current in the three-phase electric drive system and providing a basic data basis for subsequent current rationality verification. On this basis, this embodiment assumes that when the three-phase current satisfies the symmetry condition without amplitude error and phase error, the third-phase current signal can be represented by a specific relationship of the two-phase current signals. At this time, coordinate transformation can be performed only based on the two-phase current signals, and then the two-phase current signals in the three-phase electric drive system are converted into two-axis current components in the two-phase coordinate system, without collecting all three-phase current signals, thereby reducing the number of current detection devices and saving hardware costs. It is also not necessary to calculate the third-phase current signal based on the two-phase current signals, which is beneficial to simplifying data processing and reducing computing power consumption, thereby reducing the detection cost in multiple aspects. In this embodiment, determining the current fundamental frequency based on the two-axis current components can improve the accuracy of the current fundamental frequency and provide a reference basis for subsequent extraction of the current ripple component. The two-axis current combination feature quantity generated based on the two-axis current components can reflect the cooperative relationship between the two-axis current components, which is beneficial to subsequent identification of whether there are errors such as current amplitude and phase from the current ripple component extracted from the two-axis current combination feature quantity, thereby reducing the difficulty of current rationality verification. At the same time, since the two-axis current combination feature quantity in this embodiment is generated based on the two-axis current components, the fundamental frequency corresponding to the two-axis current combination feature quantity is determined by the current fundamental frequency, and the target frequency when extracting the current ripple amplitude is also determined based on the current fundamental frequency. Therefore, extracting the current ripple component of the two-axis current combination feature quantity at the target frequency in this embodiment can accurately and effectively extract the fluctuation characteristics of the current. When there is no amplitude error and phase error in the three-phase current of the three-phase electric drive system, the amplitude of the two-axis current combination feature quantity should be a constant value and theoretically no current ripple component will be generated. Thus, the current ripple component extracted from the two-axis current combination feature quantity at the target frequency in this embodiment can reflect the actual situation of the amplitude error and / or phase error of the three-phase current, and then determine the current verification result of the three-phase electric drive system based on the current ripple component. In this way, this embodiment can indirectly evaluate the current rationality of the three-phase electric drive system by collecting two-phase current signals, ensure the reliability of the current verification result, and then realize the replacement of the three-phase current detection device with the two-phase current detection device. Compared with the method of collecting three-phase current for current rationality verification, this embodiment reduces the detection cost in multiple aspects and is also beneficial to reducing the hardware random failure rate and further improving the reliability of current rationality verification.

[0060] Optionally, determining the current fundamental frequency based on the two-axis current components includes:

[0061] Performing an arctangent process on the two-axis current components to obtain the electrical angle of the two-phase current signals;

[0062] Determining the current fundamental frequency according to the change rate of the electrical angle.

[0063] Specifically, in this embodiment, the two-axis current components can be regarded as the projections of the three-phase current synthesis vector on the α-axis and β-axis in the two-phase stationary coordinate system. Therefore, in this embodiment, the arctangent function can be used to obtain the angle between the vector and the positive direction of the α-axis through these two projections (i.e., the two-axis current components), and this angle is the electrical angle, which reflects the instantaneous phase position of the current during its periodic change.

[0064] In one embodiment, the current fundamental frequency represents the basic frequency of the periodic change of the current. In a complete current cycle, the electrical angle of the current changes from 0 to 2π. The higher the current fundamental frequency, the faster the change of the electrical angle per unit time. The current fundamental frequency can be obtained by calculating the change rate of the electrical angle with respect to time. For example, the electrical angles corresponding to two continuously sampled two-phase current signals can be obtained, and then the ratio of the difference between the two electrical angles to the preset sampling period is used as the change rate of the electrical angle, and then the current fundamental frequency is obtained (such as directly using the change rate of the electrical angle as the current fundamental frequency).

[0065] In this embodiment, the two-axis current components are obtained after coordinate transformation of the two-phase current signals, and can reflect the dynamic characteristics of the current from different dimensions. Obtaining the electrical angle of the two-phase current signals through arctangent processing of the two-axis current components is beneficial to improving the accuracy and reliability of the electrical angle. On this basis, this embodiment determines the current fundamental frequency according to the change rate of the electrical angle, can effectively capture the dynamic change of the current fundamental frequency, and thus simply, quickly and accurately determine the current fundamental frequency.

[0066] Optionally, before determining the current fundamental frequency according to the change rate of the electrical angle, it further includes:

[0067] Obtain multiple two-phase current signals obtained by sampling, and arrange the electrical angles corresponding to the two-phase current signals according to the sampling order of each two-phase current signal to obtain an electrical angle sequence;

[0068] Obtain the difference between each electrical angle and the target electrical angle to obtain a plurality of electrical angle differences; wherein, the target electrical angle includes the electrical angle that is a preset interval away from this electrical angle in the electrical angle sequence;

[0069] Obtain the change rate of the electrical angle according to the ratio of the sum of each electrical angle difference to the target period; wherein, the target period is determined based on the preset sampling period, the preset interval and the number of electrical angle differences.

[0070] Specifically, in this embodiment, after sampling the two-phase current signals according to a preset sampling period, after each two-phase current signal is sampled, coordinate transformation can be performed on it to obtain two-axis current components, and the arctangent processing is performed on the two-axis current components to obtain the electrical angle corresponding to the two-phase current signal. After obtaining the sampled two-phase current signals (such as 50 two-phase current signals continuously collected according to the preset sampling period), the electrical angles corresponding to the two-phase current signals can be arranged according to the sampling order of each two-phase current signal to obtain an electrical angle sequence. On this basis, for each electrical angle, the difference between the electrical angle and the target electrical angle can be obtained to obtain the electrical angle difference corresponding to the two-phase current signal. Among them, the target electrical angle includes the electrical angle that is separated from this electrical angle by a preset interval in the electrical angle sequence. The preset interval can be set in advance. Assuming that the preset interval is 1, the previous electrical angle of this electrical angle can be used as the target electrical angle, and then the electrical angle difference can be obtained according to the difference between the electrical angle and the target electrical angle. On this basis, the change rate of the electrical angle can be obtained according to the ratio of the sum of the electrical angle differences to the target period, and the change rate of the electrical angle satisfies:

[0071]

[0072] Among them, ω e represents the change rate of the electrical angle; t represents the sampling moment; θ t represents the electrical angle corresponding to the two-axis current signal collected at the sampling moment t (that is, the t-th electrical angle in the electrical angle sequence); θ t-m represents the electrical angle corresponding to the two-axis current signal collected at the sampling moment t - m (that is, the (t - m)-th electrical angle in the electrical angle sequence), m represents the preset interval; n represents the number of sampling moments (that is, the number of two-phase current signals, and also the number of electrical angles in the electrical angle sequence); T1 represents the preset sampling period.

[0073] In this embodiment, by obtaining a plurality of sampled two-phase current signals, arranging the electrical angles corresponding to the two-phase current signals according to the sampling order of each two-phase current signal to obtain an electrical angle sequence, and selecting the target electrical angle at a preset interval to calculate the difference between the electrical angle and the target electrical angle, the electrical angle changes of multiple sampling points (that is, two-phase current signals) within a certain time span are comprehensively considered. On this basis, this embodiment determines the target period based on the preset sampling period, the preset interval, and the number of electrical angle differences, and obtains the change rate of the electrical angle according to the ratio of the sum of the electrical angle differences to the target period, which is also beneficial to avoiding large deviations in the change rate result caused by factors such as current fluctuations and ensuring the accuracy of the change rate.

[0074] Optionally, the two-axis current combined feature quantity includes the two-axis vector synthesis current obtained by vector synthesis of the two-axis current components; the target frequency includes twice the current fundamental frequency.

[0075] Specifically, the two-axis vector synthesis current referred to in this embodiment is obtained based on the vector synthesis of two-axis current components, such as the sum of the squares of the two-axis current components, which can indirectly reflect the overall situation of the sum of the squares of the three-phase currents. The target frequency includes twice the current fundamental frequency. For example, if the current fundamental frequency is 50 Hz, the target frequency can be 100 Hz.

[0076] In this embodiment, when the three-phase currents in the three-phase electric drive system satisfy the symmetry condition, the amplitude of the current corresponding to the vector synthesis of the two-axis current components should theoretically be a constant value. When there are amplitude errors and / or phase errors in the three-phase currents, it means that the three-phase currents are no longer completely symmetric in the ideal case. At this time, there are usually obvious current ripple components in the two-axis vector synthesis current at twice the current fundamental frequency. Therefore, the two-axis current combination feature quantity in this embodiment includes the two-axis vector synthesis current, and the target frequency includes twice the current fundamental frequency, which is convenient for subsequently extracting the current ripple components of the two-axis vector synthesis current at twice the current fundamental frequency, so as to quickly and accurately identify whether there are amplitude errors and / or phase errors in the three-phase currents, which is beneficial to improving the reliability of current rationality verification, and further ensuring the safety of the operation of the three-phase electric drive system.

[0077] Optionally, extracting the current ripple components of the two-axis current combination feature quantity at the target frequency includes:

[0078] Performing orthogonal decomposition on the two-axis vector synthesis current at twice the current fundamental frequency to obtain the sine projection component and the cosine projection component of the two-axis vector synthesis current in the frequency domain;

[0079] Based on the sine projection component and the cosine projection component, obtaining the current ripple components; wherein, the real part of the current ripple components is determined based on the cosine projection component, and the imaginary part of the current ripple components is determined based on the sine projection component.

[0080] Specifically, the orthogonal decomposition referred to in this embodiment means converting the two-axis vector synthesis current at twice the current fundamental frequency into the sine projection component and the cosine projection component in the orthogonal coordinate system. Among them, the sine projection component represents the part of the current fluctuation in the two-axis vector synthesis current that is related to the sine function, and the cosine projection component represents the part of the current fluctuation that is related to the cosine function.

[0081] In one embodiment, the two-axis vector synthesis current can be expressed as:

[0082]

[0083] Wherein, represents the square of the current component obtained by converting the two-phase current signal corresponding to the t sampling moment to the α axis; It represents the square of the current component obtained by converting the two-phase current signals corresponding to the t sampling moment to the β axis; x(t) represents the two-axis vector synthesized current obtained based on the two-phase current signals corresponding to the t sampling moment.

[0084] On this basis, the two-axis vector synthesized current can be orthogonally decomposed at twice the current fundamental frequency to obtain the sine projection component and cosine projection component of the two-axis vector synthesized current in the frequency domain:

[0085]

[0086] where, a(t) represents the sine projection component; b(t) represents the cosine projection component; ω e represents the current fundamental frequency; K represents the multiple of the current fundamental frequency (K = 2 in this embodiment); W represents the change rate of the electrical angle of the current ripple component (i.e., angular velocity); T2 represents the period of the current ripple component. On this basis, the real part of the current ripple component can be determined based on the cosine projection component, and the imaginary part of the current ripple component can be determined according to the sine projection component, thereby obtaining the current ripple component.

[0087] In this embodiment, by orthogonally decomposing the two-axis vector synthesized current at twice the current fundamental frequency to obtain the sine projection component and cosine projection component of the two-axis vector synthesized current in the frequency domain, the characteristics of the two-axis vector synthesized current at this frequency can be described from different dimensions, which is beneficial to accurately capture the fluctuation characteristics of the two-axis vector synthesized current at twice the current fundamental frequency. Thus, the current ripple component obtained based on the sine projection component and cosine projection component can accurately reflect the fluctuation of the three-phase current, ensuring the reliability of the current verification result.

[0088] Optionally, determining the current verification result of the three-phase electric drive system based on the current ripple component includes:

[0089] Determining the ratio between the first average amplitude and the second average amplitude to obtain the target ratio; where the first average amplitude includes the average amplitudes corresponding to multiple current ripple components; the second average amplitude includes the average amplitudes corresponding to multiple two-axis vector synthesized currents;

[0090] When the target ratio is greater than the preset threshold, the current verification result is that the verification fails.

[0091] Specifically, in this embodiment, the first average amplitude includes the average amplitudes corresponding to multiple current ripple components, and the second amplitude includes the average amplitudes corresponding to multiple two-axis vector synthesized currents. For example, the first average amplitude can be expressed as:

[0092]

[0093] where, represents the average amplitude corresponding to multiple two-axis vector synthesized currents; A1(t) represents the amplitude of the two-axis vector synthesized current obtained from the two-phase current signals collected at the t sampling moment.

[0094] The second average amplitude can be expressed as:

[0095]

[0096] wherein, represents the average amplitude corresponding to multiple current ripple components; A2(t) represents the amplitude of the current ripple components extracted from the two-axis vector synthesized current obtained from the two-phase current signals collected at the t sampling moment.

[0097] In this embodiment, the target ratio obtained according to the ratio between the average amplitude corresponding to multiple current ripple components and the average amplitude corresponding to multiple two-axis vector synthesized currents can reflect the severity of current fluctuations within the sampling time. The larger the target ratio, the greater the proportion of current ripple components, and the more significant the imbalance and asymmetry of the three-phase currents. When the target ratio is greater than the preset threshold (such as 10%), it indicates that relatively serious amplitude errors and / or phase errors may have occurred. At this time, the rationality of the current cannot be guaranteed, and the current verification result is verification failure, which is conducive to indirectly evaluating the deviation of the three-phase current sum based on the two-axis vector synthesized current, thereby quickly and accurately identifying potential safety hazards.

[0098] Optionally, after the current verification result is verification failure, it may further include: controlling the three-phase electric drive system to enter a preset safety mode (such as a shutdown protection mode), which is beneficial to avoiding safety failures that may be caused when controlling the three-phase electric drive system based on unreasonable three-phase currents, and improving the safety and stability of the operation of the three-phase electric drive system.

[0099] Optionally, before determining the current fundamental frequency based on the two-axis current components, the following steps are further included:

[0100] Determine whether the two-phase current signals meet the preset verification conditions; wherein, the preset verification conditions include that the sampling quantity corresponding to the two-phase current signals is greater than the preset quantity, and / or, the sampling duration corresponding to the two-phase current signals is greater than the preset duration;

[0101] If so, determine the current fundamental frequency based on the two-axis current components;

[0102] If not, return to the step of sampling the two-phase current signals in the three-phase electric drive system according to the preset sampling period.

[0103] In this embodiment, the preset verification condition can be set in advance. For example, the required number of samples can be set in advance according to the accuracy requirement as the preset number (such as 50), or the sampling duration can be set in advance according to the accuracy requirement in combination with the preset sampling period. Assuming that the preset sampling period is 2 microseconds, the preset duration can be greater than 100 microseconds. Before determining the current fundamental frequency based on the two-axis current components, it can be determined whether the two-phase current signals meet the preset verification condition. If so, the current fundamental frequency can be determined based on the two-axis current components. If not, the step of sampling the two-phase current signals in the three-phase electric drive system according to the preset sampling period is returned to continue sampling the two-phase current signals. This is beneficial to ensuring that a sufficient number of two-phase current signals can be sampled before performing the current rationality verification, further improving the reliability of the verification result.

[0104] As Figure 2 shown, a current verification device 200 provided by an embodiment of the present invention includes:

[0105] A sampling module 210, configured to sample the two-phase current signals in the three-phase electric drive system according to a preset sampling period, and convert the sampled two-phase current signals into two-axis current components in a two-phase coordinate system;

[0106] A determination module 220, configured to determine the current fundamental frequency based on the two-axis current components, and generate a two-axis current combined feature quantity based on the two-axis current components;

[0107] A verification module 230, configured to extract the current ripple component of the two-axis current combined feature quantity at a target frequency, and determine the current verification result of the three-phase electric drive system based on the current ripple component; wherein, the target frequency is determined based on the current fundamental frequency.

[0108] The technical effects that can be produced by the current verification device and the current verification method provided in this embodiment are basically the same, and will not be elaborated here.

[0109] As Figure 3 shown, a three-phase electric drive system 300 provided by an embodiment of the present invention includes a memory 310 and a processor 320; the memory 310 is used to store a computer program; the processor 320 is used to implement the current verification method as described above when executing the computer program.

[0110] Or, a three-phase electric drive system 300 includes a memory 310 and a processor 320 coupled to the memory 310; the memory 310 is configured to store a computer program; the processor 320 is configured to perform the following operations when executing the computer program:

[0111] Sample the two-phase current signals in the three-phase electric drive system according to a preset sampling period, and convert the sampled two-phase current signals into two-axis current components in a two-phase coordinate system;

[0112] Determine the current fundamental frequency based on the two-axis current components, and generate a two-axis current combined feature quantity based on the two-axis current components;

[0113] Extract the current ripple component of the two-axis current combined feature quantity at the target frequency, and determine the current verification result of the three-phase electric drive system based on the current ripple component; wherein, the target frequency is determined based on the current fundamental frequency.

[0114] The three-phase electric drive system and the current verification method provided in this embodiment can produce basically the same technical effects, which will not be elaborated here.

[0115] A computer-readable storage medium provided by an embodiment of the present invention, on which a computer program is stored. When the computer program is executed by a processor, the current verification method described above is implemented.

[0116] Or, a non-volatile computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the processor performs the following operations:

[0117] Sample the two-phase current signals in the three-phase electric drive system according to a preset sampling period, and convert the sampled two-phase current signals into two-axis current components in a two-phase coordinate system;

[0118] Determine the current fundamental frequency based on the two-axis current components, and generate a two-axis current combined feature quantity based on the two-axis current components;

[0119] Extract the current ripple component of the two-axis current combined feature quantity at the target frequency, and determine the current verification result of the three-phase electric drive system based on the current ripple component; wherein, the target frequency is determined based on the current fundamental frequency.

[0120] The computer-readable storage medium and the current verification method provided in this embodiment can produce basically the same technical effects, which will not be elaborated here.

[0121] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above various methods. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. One can select some or all of the units according to actual needs to achieve the purpose of the solution of the embodiments of the present invention. In addition, the functional units in the various embodiments of the present invention can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0122] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A current calibration method, characterized in that, include: Sampling two-phase current signals in a three-phase electric drive system according to a preset sampling period, and converting the sampled two-phase current signals into two-axis current components in a two-phase coordinate system; determining a current fundamental frequency based on the two-axis current components, and generating a two-axis current combination characteristic quantity based on the two-axis current components; A current ripple component of the two-axis current combination characteristic quantity at a target frequency is extracted, and a current verification result of the three-phase electric drive system is determined based on the current ripple component; wherein the target frequency is determined based on the current fundamental frequency.

2. The current calibration method according to claim 1, wherein The determining of the current fundamental frequency based on the two-axis current components includes: Performing arc tangent processing on the two-axis current components to obtain electrical angles of the two-phase current signals; The current fundamental frequency is determined according to the rate of change of the electrical angle.

3. The current calibration method according to claim 2, wherein Before determining the current fundamental frequency according to the rate of change of the electrical angle, the method further includes: Acquire the plurality of two-phase current signals obtained by sampling, and arrange the corresponding electrical angles according to the sampling order of the two-phase current signals to obtain an electrical angle sequence; Obtaining the difference between each of the electrical angles and a target electrical angle to obtain a plurality of electrical angle differences; wherein the target electrical angle includes the electrical angle in the electrical angle sequence that is at a preset interval from the electrical angle; The rate of change of the electrical angle is obtained according to the ratio of the sum of the electrical angle differences to a target period; wherein the target period is determined based on the preset sampling period, the preset interval and the number of the electrical angle differences.

4. The current calibration method according to claim 1, wherein The two-axis current combination characteristic quantity includes a two-axis vector synthesis current obtained by vector synthesis of the two-axis current components; and the target frequency includes twice the current fundamental frequency.

5. The current calibration method according to claim 4, wherein The extracting of the current ripple component of the two-axis current combination characteristic quantity at the target frequency includes: orthogonally decomposing the two-axis vector composite current at twice the current fundamental frequency to obtain a sine projection component and a cosine projection component of the two-axis vector composite current in the frequency domain; The current ripple component is obtained based on the sine projection component and the cosine projection component; wherein the real part of the current ripple component is determined based on the cosine projection component, and the imaginary part of the current ripple component is determined based on the sine projection component.

6. The current verification method according to claim 4, characterized in that: Determining a current verification result of the three-phase electric drive system based on the current ripple component includes: Determining a ratio between a first average amplitude and a second average amplitude to obtain a target ratio; wherein the first average amplitude includes an average amplitude corresponding to a plurality of the current ripple components; and the second average amplitude includes an average amplitude corresponding to a plurality of the two-axis vector composite currents; When the target ratio is greater than a preset threshold, the current verification result is verification failure.

7. The current verification method according to any one of claims 1 to 6, characterized in that: Before determining the current fundamental frequency based on the two-axis current components, the method further includes: Determine whether the two-phase current signals meet preset verification conditions; wherein the preset verification conditions include: the number of samples corresponding to the two-phase current signals is greater than a preset number, and / or the sampling time length corresponding to the two-phase current signals is greater than a preset time length; If yes, determining the current fundamental frequency based on the two-axis current components; If not, return to the step of sampling the two-phase current signals in the three-phase electric drive system according to the preset sampling period.

8. A current calibration device, characterized in that, It includes: A sampling module, configured to sample the two-phase current signals in the three-phase electric drive system according to the preset sampling period, and convert the sampled two-phase current signals into two-axis current components in a two-phase coordinate system; A determination module, configured to determine the current fundamental frequency based on the two-axis current components, and generate a two-axis current combined feature quantity based on the two-axis current components; A verification module, configured to extract the current ripple component of the two-axis current combined feature quantity at the target frequency, and determine the current verification result of the three-phase electric drive system based on the current ripple component; wherein, the target frequency is determined based on the current fundamental frequency.

9. A three-phase electric drive system, characterized in that, It includes a memory and a processor; The memory is used to store a computer program; The processor is configured to, when executing the computer program, implement the current verification method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, A computer program is stored on the storage medium, and when the computer program is executed by the processor, the current verification method according to any one of claims 1 to 7 is implemented.

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