Method and device for observing stator flux linkage and electromagnetic torque of permanent magnet synchronous motor

Abstract

The application relates to a permanent magnet synchronous motor stator flux linkage and electromagnetic torque observation method and device, the stator flux linkage observation method comprising: obtaining the measurement values of the control voltage and the stator current of the permanent magnet synchronous motor in the current control period three-phase static coordinate system and transforming into the measurement values of the control voltage and the stator current in the synchronous rotating coordinate system; substituting into the stator current observation model to calculate the stator current observation value, wherein the stator current observation model defines the relationship between the stator current observation value and the measurement values of the control voltage and the stator current, the stator current observation error and the system disturbance; obtaining the error feedback of the stator current observation model according to the stator current observation value and the system disturbance; extracting the observation error of the stator flux linkage from the error feedback and performing low-pass filtering; substituting the filtered observation error of the stator flux linkage into the stator flux linkage observation model to calculate the stator flux linkage observation value. The application can effectively observe the stator flux linkage and the electromagnetic torque which are difficult to directly measure.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor control technology, and in particular to a method and apparatus for observing the stator flux and electromagnetic torque of a permanent magnet synchronous motor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) use permanent magnets for excitation, eliminating the need for problematic slip rings and brushes, resulting in a simpler structure and improved reliability. Furthermore, the absence of excitation current and excitation losses enhances efficiency and power density. Therefore, PMSMs are widely used in servo drives and electric vehicle drives. Direct torque control (DTC) is one of the main control technologies for PMSMs, and its performance depends on the accuracy of observing the stator flux linkage and electromagnetic torque, which are typically not directly measurable.

[0003] Therefore, designing a highly accurate and robust method and device for observing stator flux linkage and electromagnetic torque is crucial for improving the performance of direct torque control. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for observing stator flux linkage and electromagnetic torque of a permanent magnet synchronous motor. This method can effectively observe stator flux linkage and electromagnetic torque, which are difficult to measure directly. It has strong parameter robustness and provides an effective reference for direct torque control of permanent magnet synchronous motors, thereby improving control performance.

[0005] To achieve the above objectives, the present invention provides a method for observing the stator flux linkage of a permanent magnet synchronous motor, comprising the following steps:

[0006] Obtain the measured values ​​of control voltage and stator current of the permanent magnet synchronous motor in the three-phase stationary coordinate system during the current control cycle;

[0007] The measured values ​​of control voltage and stator current in the three-phase stationary coordinate system are transformed into the measured values ​​of control voltage and stator current in the synchronous rotating coordinate system, respectively.

[0008] The measured values ​​of the control voltage and stator current are substituted into the stator current observation model to calculate the stator current observation value. The stator current observation model defines the relationship between the stator current observation value and the measured values ​​of the control voltage and stator current, the stator current observation error, and the system disturbance. The stator current observation error is determined based on the stator current observation value and the measured value of the stator current, and the system disturbance is obtained iteratively based on the stator current observation error.

[0009] Error feedback of the stator current observation model is obtained based on the stator current observation value and the system disturbance;

[0010] The stator flux observation error is extracted from the error feedback of the stator current observation model and then low-pass filtered.

[0011] The stator flux linkage observation error after low-pass filtering is substituted into the stator flux linkage observation model to calculate the stator flux linkage observation value to achieve stator flux linkage observation. The stator flux linkage observation model defines the relationship between the stator flux linkage observation value, the stator flux linkage observation error, and the stator current observation value.

[0012] Optionally, Clarke transformation and Park transformation can be used to transform the measured values ​​of control voltage and stator current in the three-phase stationary coordinate system into the measured values ​​of control voltage and stator current in the synchronous rotating coordinate system, respectively.

[0013] Optionally, the stator current observation model is:

[0014]

[0015] Among them, i od and i oq For the stator current observation value, i d and i q The measured value of the stator current, u d and u q To control the voltage, e id and e iq For the stator current observation error, D d and D q For system disturbances, the subscripts d and q represent the d-axis and q-axis of the synchronous rotating coordinate system, respectively, and (k) and (k+1) represent the k-th and (k+1)-th control cycles, respectively. d and L q R is the stator inductance parameter used in the stator current observation model. s ψ is the stator resistance parameter used in the stator current observation model. pm ω is the permanent magnet flux linkage parameter used in the stator current observation model. r T is the electric angular velocity of the motor. s The control period is β1, which is the current error compensation coefficient.

[0016] The stator current observation error is:

[0017]

[0018] The iterative formula for the system disturbance is:

[0019]

[0020] Where β2 is the perturbation iteration coefficient.

[0021] Optionally, the error feedback of the stator current observation model is:

[0022]

[0023] The observation error of the stator flux linkage is expressed as:

[0024]

[0025] The stator flux observation error is extracted from the error feedback of the stator current observation model described in equation (1), and low-pass filtered. Then, it is combined with equation (2) to obtain:

[0026]

[0027] Among them, e ψd and e ψd For the observation error of stator flux linkage, L d0 and L q0 ψ is the actual inductance value of the motor. pm0 is the actual permanent magnet flux linkage value of the motor, and LPF is the low-pass filter.

[0028] Optionally, the stator flux linkage observations are calculated as follows:

[0029]

[0030] Where, ψ do and ψ qo These are the stator flux linkage observations.

[0031] Based on the same inventive concept, this invention also provides a method for observing the electromagnetic torque of a permanent magnet synchronous motor, comprising the following steps:

[0032] Stator flux linkage observations were obtained using the method described above; and,

[0033] The electromagnetic torque observation value is calculated based on the stator current observation value and the stator flux linkage observation value.

[0034] Optionally, the electromagnetic torque observations are calculated as follows:

[0035]

[0036] Among them, T eo (k+1) Electromagnetic torque observation, p n This represents the number of pole pairs of the motor.

[0037] Based on the same inventive concept, the present invention also provides a stator flux linkage monitoring device for permanent magnet synchronous motors, comprising:

[0038] The acquisition module is used to acquire the measured values ​​of the control voltage and stator current of the permanent magnet synchronous motor in the three-phase stationary coordinate system during the current control cycle.

[0039] The transformation module is used to transform the measured values ​​of control voltage and stator current in the three-phase stationary coordinate system into the measured values ​​of control voltage and stator current in the synchronous rotating coordinate system, respectively.

[0040] A stator current observation model is used to calculate the stator current observation value based on the measured values ​​of the control voltage and stator current. The stator current observation model defines the relationship between the stator current observation value and the measured values ​​of the control voltage and stator current, the stator current observation error, and the system disturbance. The stator current observation error is determined based on the stator current observation value and the measured value of the stator current, and the system disturbance is obtained iteratively based on the stator current observation error.

[0041] An error feedback module is used to obtain error feedback of the stator current observation model based on the stator current observation value and the system disturbance;

[0042] The extraction module is used to extract the observation error of the stator flux linkage from the error feedback of the stator current observation model and perform low-pass filtering;

[0043] A stator flux linkage observation model is used to calculate the stator flux linkage observation value based on the observation error of the stator flux linkage after low-pass filtering in order to realize the observation of the stator flux linkage. The stator flux linkage observation model defines the relationship between the stator flux linkage observation value, the stator flux linkage observation error, and the stator current observation value.

[0044] Based on the same inventive concept, the present invention also provides an electromagnetic torque observation system for a permanent magnet synchronous motor, including an electromagnetic torque observation model and a permanent magnet synchronous motor stator flux linkage observation device as described above. The electromagnetic torque observation model is used to calculate the electromagnetic torque observation value based on the stator flux linkage observation value and the stator current observation value obtained by the permanent magnet synchronous motor stator flux linkage observation device.

[0045] The method and apparatus for observing stator flux linkage and electromagnetic torque of permanent magnet synchronous motors provided by this invention have at least one of the following beneficial effects:

[0046] 1) Strong robustness: Traditional observation models may be sensitive to changes in system parameters, while designs based on disturbance observation and error feedback principles can better adapt to parameter changes and improve the robustness of the system by estimating and compensating for system disturbances in real time.

[0047] 2) Excellent real-time performance: By using the current prediction error as feedback, this invention can quickly respond to dynamic changes in the system. This design makes the observation model perform excellently in real-time control systems. High computational efficiency: By using the extended state observation model and the idea of ​​disturbance observation, this invention can provide more accurate estimation results without significantly increasing computational complexity, which is especially important for resource-constrained systems (such as microcontrollers).

[0048] 3) Low noise processing: Low-pass filtering is used to process the observation results, which reduces the impact of noise and improves the accuracy of the observation. This is very useful for systems that require high-precision control.

[0049] 4) Multi-objective control capability: This invention can not only estimate flux linkage and torque, but also provide real-time feedback on system disturbances. This enables the control algorithm to effectively balance multiple control objectives. High flexibility: The design of the observation model allows for flexible application in different control strategies, such as direct torque control (DTC) and dead-zone control. This flexibility makes the observation model play an important role in various motor control applications. Furthermore, this invention can effectively improve the robustness and control performance of the system under parameter variations and the presence of unmodeled disturbances. Attached Figure Description

[0050] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0051] Figure 1 The flowchart of the stator flux linkage observation method for a permanent magnet synchronous motor provided in an embodiment of the present invention is shown.

[0052] Figure 2 A schematic diagram of the stator flux linkage observation of a permanent magnet synchronous motor provided in an embodiment of the present invention;

[0053] Figure 3 The observation results of stator flux linkage and electromagnetic torque of a permanent magnet synchronous motor provided in an embodiment of the present invention;

[0054] Figure 4 This is a schematic diagram of a verification platform for a permanent magnet synchronous motor stator flux linkage observation method provided in an embodiment of the present invention;

[0055] Figure 5 A comparison of the torque step response performance of three deadbeat control methods provided in an embodiment of the present invention when the electromagnetic torque reference value changes by 0.2 N·m;

[0056] Figure 6 A comparison of the torque step response performance of three deadbeat control methods provided in an embodiment of the present invention when the electromagnetic torque reference value changes by 0.8 N·m;

[0057] Figure 7 A comparison of flux linkage step response performance of three deadbeat control methods when the stator flux linkage reference value changes by 0.005 Wb, as provided in an embodiment of the present invention;

[0058] Figure 8 A comparison of three deadbeat control methods provided in an embodiment of the present invention with speed step response and rated load torque and constant stator flux reference value;

[0059] Figure 9 This invention provides a comparison of the flux reduction performance of three deadbeat control methods when the stator flux reference value decreases from 0.08 to 0.07 Wb, according to an embodiment of the invention. Detailed Implementation

[0060] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the purpose of the embodiments of this invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only used to complement the content disclosed in the specification, for those skilled in the art to understand and read, and are not intended to limit the implementation conditions of this invention. Any modifications to the structure, changes in proportions, or adjustments to the size, if they are the same as or similar to the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0061] As used herein, the singular forms “a,” “an,” and “the” include plural objects unless otherwise expressly indicated. As used herein, the term “or” is generally used to include the meaning of “and / or” unless otherwise expressly indicated.

[0062] In practical digital control systems, there is a control cycle delay between the calculation of the control reference voltage and its application to the permanent magnet synchronous motor. Therefore, the stator current, stator flux linkage, and electromagnetic torque for the next control cycle should be predicted in the deadbeat-free control algorithm to compensate for this delay. Furthermore, disturbances always exist in the control system due to variations in machine parameters and other unmodeled factors, requiring disturbance estimation to improve system robustness.

[0063] Based on this, this invention designs a method for observing stator flux linkage and electromagnetic torque of a permanent magnet synchronous motor. First, a stator current observation model is designed based on the fundamental principles of disturbance observation and error feedback to achieve accurate stator current observation. Next, the observation error of the stator flux linkage is extracted from the error feedback of the stator current observation model. This observation error is then low-pass filtered to eliminate high-frequency interference and compensated into the stator flux linkage observation model to achieve accurate stator flux linkage observation. Finally, the electromagnetic torque is calculated based on the observed stator current and stator flux linkage. This invention can accurately observe the stator flux linkage and electromagnetic torque of a permanent magnet synchronous motor, even if the actual parameters of the motor deviate from the parameters used in the observation model. Since stator flux linkage and electromagnetic torque are usually not directly measurable, the observation data of this invention can compensate for the measurement limitations and provide reliable motor state information for direct torque control of permanent magnet synchronous motors.

[0064] For details, please refer to Figures 1-2 This embodiment provides a method for observing the stator flux linkage of a permanent magnet synchronous motor, including the following steps:

[0065] S1. Obtain the measured values ​​of control voltage and stator current of the permanent magnet synchronous motor in the three-phase stationary coordinate system during the current control cycle;

[0066] S2. Transform the measured values ​​of control voltage and stator current in the three-phase stationary coordinate system into the measured values ​​of control voltage and stator current in the synchronous rotating coordinate system, respectively.

[0067] S3. Substitute the measured values ​​of control voltage and stator current into the stator current observation model to calculate the stator current observation value. The stator current observation model defines the relationship between the stator current observation value and the measured values ​​of control voltage and stator current, the stator current observation error, and the system disturbance. The stator current observation error is determined based on the stator current observation value and the measured value of stator current, and the system disturbance is obtained iteratively based on the stator current observation error.

[0068] S4. Obtain the error feedback of the stator current observation model based on the stator current observation value and system disturbance;

[0069] S5. Extract the stator flux observation error from the error feedback of the stator current observation model and perform low-pass filtering;

[0070] S6. Substitute the observation error of the stator flux linkage after low-pass filtering into the stator flux linkage observation model to calculate the stator flux linkage observation value to realize the observation of the stator flux linkage. The stator flux linkage observation model defines the relationship between the stator flux linkage observation value, the stator flux linkage observation error, and the stator current observation value.

[0071] First, execute S1 to obtain the measured values ​​of the control voltage and stator current of the permanent magnet synchronous motor in the three-phase stationary (abc) coordinate system during the current control cycle. This step can be implemented using existing technology, and will not be elaborated upon in this invention.

[0072] Then, step S2 is executed to transform the measured values ​​of control voltage and stator current in the three-phase stationary coordinate system into measured values ​​of control voltage and stator current in the synchronous rotating (dq) coordinate system. In this embodiment, Clarke transform and Park transform are used to transform the measured values ​​of control voltage and stator current in the three-phase stationary coordinate system into measured values ​​of control voltage and stator current in the synchronous rotating coordinate system; wherein,

[0073] The Clarke transform is as follows:

[0074]

[0075] Among them, X a X b X c X represents the measured value of the control voltage or stator current in a three-phase stationary coordinate system. α X β To control the α-axis and β-axis components of the voltage or stator current in the orthogonal two-phase stationary (αβ) coordinate system.

[0076] The Park transformation is as follows:

[0077]

[0078] Among them, X d X q The d-axis and q-axis components of the measured values ​​of control voltage or stator current in a synchronous rotating coordinate system are given, where θ is the real-time electrical angle of the rotor.

[0079] Then, S3 is executed, substituting the measured values ​​of control voltage and stator current into the stator current observation model to calculate the stator current observation value. The stator current observation model defines the relationship between the stator current observation value and the measured values ​​of control voltage and stator current, the stator current observation error, and the system disturbance. The stator current observation error is determined based on the stator current observation value and the measured value of stator current, and the system disturbance is obtained iteratively based on the stator current observation error.

[0080] In this embodiment, the stator current observation model is designed based on the principles of disturbance observation and error feedback. The stator current observation model is as follows:

[0081]

[0082] Among them, i od and i oqFor the stator current observation value, i d and i q The measured value of the stator current, u d and u q To control the voltage, e id and e iq For the stator current observation error, D d and D q For system disturbances, the subscripts d and q represent the d-axis and q-axis of the synchronous rotating coordinate system, respectively, and (k) and (k+1) represent the k-th and (k+1)-th control cycles, respectively. d and L q R is the stator inductance parameter used in the stator current observation model. s ψ is the stator resistance parameter used in the stator current observation model. pm ω is the permanent magnet flux linkage parameter used in the stator current observation model. r T is the electric angular velocity of the motor. s The control period is β1, which is the current error compensation coefficient.

[0083] The stator current observation error is:

[0084]

[0085] The iterative formula for system disturbance is:

[0086]

[0087] Where β2 is the perturbation iteration coefficient.

[0088] Next, S4 is executed to obtain the error feedback of the stator current observation model based on the stator current observation value and system disturbance, and S5 is executed to extract the observation error of the stator flux linkage from the error feedback of the stator current observation model and perform low-pass filtering.

[0089] In this embodiment, the error feedback of the stator current observation model is:

[0090]

[0091] The observation error of the stator flux linkage is expressed as:

[0092]

[0093] The stator flux observation error is extracted from the error feedback of the stator current observation model in equation (1), low-pass filtered, and then combined with equation (2) to obtain:

[0094]

[0095] Among them, e ψd and eψq For the observation error of stator flux linkage, L d0 and L q0 ψ is the actual inductance value of the motor. pm0 is the actual permanent magnet flux linkage value of the motor, and LPF is the low-pass filter.

[0096] Finally, step S6 is executed, substituting the observation error of the stator flux linkage after low-pass filtering into the stator flux linkage observation model to calculate the stator flux linkage observation value to achieve stator flux linkage observation. The stator flux linkage observation model defines the relationship between the stator flux linkage observation value, the stator flux linkage observation error, and the stator current observation value. In this embodiment, the stator flux linkage observation value is calculated as follows:

[0097]

[0098] Where, ψ do and ψ qo These are the stator flux linkage observations.

[0099] Based on this, the present invention also provides a method for observing the electromagnetic torque of a permanent magnet synchronous motor, comprising the following steps:

[0100] The stator flux linkage observation values ​​were obtained using the stator flux linkage observation method for permanent magnet synchronous motors as described above; and,

[0101] The electromagnetic torque observation value is calculated based on the stator current observation value and the stator flux observation value.

[0102] In this embodiment, the observed electromagnetic torque is calculated as follows:

[0103] The electromagnetic torque observations are calculated as follows:

[0104]

[0105] Among them, T eo (k+1) Electromagnetic torque observation, p n This represents the number of pole pairs of the motor.

[0106] The observation results of the stator flux linkage and electromagnetic torque proposed in this invention are as follows: Figure 3 As shown, since the relevant inductance and flux linkage parameters change during motor operation, the stator inductance and permanent magnet flux linkage values ​​used in the observation model deviate from the actual values ​​of the motor. Before adding error compensation, the observed stator flux linkage values ​​deviated significantly from the actual values; after adding the relevant error compensation proposed in this invention, the observed results of stator flux linkage and electromagnetic torque are close to the true values.

[0107] Based on the same inventive concept, this invention also proposes a stator flux linkage monitoring device for a permanent magnet synchronous motor, comprising:

[0108] The acquisition module is used to acquire the measured values ​​of the control voltage and stator current of the permanent magnet synchronous motor in the three-phase stationary coordinate system during the current control cycle.

[0109] The conversion module is used to convert the measured values ​​of control voltage and stator current in the three-phase stationary coordinate system into the measured values ​​of control voltage and stator current in the synchronous rotating coordinate system, respectively.

[0110] The stator current observation model is used to calculate the stator current observation value based on the measured values ​​of control voltage and stator current. The stator current observation model defines the relationship between the stator current observation value and the measured values ​​of control voltage and stator current, the stator current observation error, and the system disturbance. The stator current observation error is determined based on the stator current observation value and the measured value of stator current, and the system disturbance is obtained iteratively based on the stator current observation error.

[0111] The error feedback module is used to obtain error feedback of the stator current observation model based on the stator current observation value and system disturbance;

[0112] The extraction module is used to extract the observation error of the stator flux linkage from the error feedback of the stator current observation model and perform low-pass filtering.

[0113] The stator flux linkage observation model is used to calculate the stator flux linkage observation value based on the observation error of the stator flux linkage after low-pass filtering, so as to realize the observation of the stator flux linkage. The stator flux linkage observation model defines the relationship between the stator flux linkage observation value, the stator flux linkage observation error, and the stator current observation value.

[0114] Based on this, the present invention also provides an electromagnetic torque observation device for a permanent magnet synchronous motor, including an electromagnetic torque observation model and a permanent magnet synchronous motor stator flux linkage observation device as described above. The electromagnetic torque observation model is used to calculate the electromagnetic torque observation value based on the stator flux linkage observation value and the stator current observation value obtained by the permanent magnet synchronous motor stator flux linkage observation device.

[0115] The method and apparatus for observing stator flux linkage and electromagnetic torque of permanent magnet synchronous motors proposed in this invention have the following innovations:

[0116] 1) Design of a stator current observation model based on disturbance observation and error feedback principles: This stator current observation model is designed based on the extended state observation model theory and incorporates the idea of ​​disturbance observation. By compensating the estimated disturbance term into the control voltage reference, this stator current observation model can better cope with uncertainties and unmodeled elements in the system;

[0117] 2) System disturbance estimation and compensation: This stator current observation model can not only predict the stator current but also estimate the system disturbance. By using the current prediction error as feedback, the observation model can suppress the current error and predict the system disturbance, thereby improving the system robustness;

[0118] 3) Adaptability under parameter changes: The present invention can correct for mismatches between the nominal machine parameters used in the controller and the actual values. This adaptability allows the system to maintain good performance even when parameters change.

[0119] 4) Use of low-pass filter: When calculating flux linkage error, a low-pass filter (LPF) is used to reduce noise, which helps to improve the accuracy of the observation results;

[0120] 5) Multi-objective control: This invention is not only used to estimate flux linkage and torque, but also to provide real-time feedback on system disturbances during dynamic processes, which enables the control algorithm to better adjust the control voltage reference under complex operating conditions.

[0121] In the field of motor control, many controllers have been designed by predecessors. For example, the sliding mode observation model estimates the system state by introducing sliding modes, which has advantages such as strong robustness and simple structure, but may produce chattering. The extended state observation model estimates all state variables of the system by expanding the system's state space, including unknown disturbances, and performs well in handling uncertainties and external disturbances. The unscented Kalman filter is a nonlinear filtering method that approximates the probability distribution of a nonlinear system through unscented transformation, and it has high accuracy in estimating the state of nonlinear systems. Gaussian process regression is a machine learning method based on Bayesian theory used to establish a relationship model between inputs and outputs, and it has advantages in handling nonlinear and uncertain systems. The adaptive observation model can automatically adjust its parameters according to the real-time feedback information of the system to adapt to changes in system parameters, and it performs well in handling parameter uncertainty and variation. The robust observation model is designed to provide stable state estimates under the presence of uncertainties and external disturbances, and it usually combines the advantages of sliding mode control and the extended state observation model.

[0122] The stator flux linkage and electromagnetic torque observation device based on the disturbance observation model provided by this invention has the following advantages compared with other common observation models:

[0123] 1) Strong robustness: Traditional observations may be sensitive to changes in system parameters, while designs based on perturbation observation and error feedback principles can better adapt to parameter changes. By estimating and compensating for system perturbations in real time, the robustness of the system is improved.

[0124] 2) Excellent real-time performance: By using the current prediction error as feedback, this invention can quickly respond to dynamic changes in the system. This design makes the observation model perform excellently in real-time control systems. High computational efficiency: By using the extended state observation model and the idea of ​​disturbance observation, this invention can provide more accurate estimation results without significantly increasing computational complexity, which is especially important for resource-constrained systems (such as microcontrollers).

[0125] 3) Low noise processing: Low-pass filters are used to process the observation results, which reduces the impact of noise and improves the accuracy of the observation. This is very useful for systems that require high-precision control.

[0126] 4) Multi-objective control capability: This invention can not only estimate flux linkage and torque, but also provide real-time feedback on system disturbances. This enables the control algorithm to effectively balance multiple control objectives. High flexibility: The design of the observation model allows for flexible application in different control strategies, such as direct torque control (DTC) and dead-zone control. This flexibility makes the observation model play an important role in various motor control applications. Furthermore, this invention can effectively improve the robustness and control performance of the system under parameter variations and the presence of unmodeled disturbances.

[0127] The following specific experiments will be used to verify the observation effect of the present invention.

[0128] like Figure 4 As shown, the control unit is a TI microcontroller LAUNCHXL-F28379D with a system clock frequency of 200MHz, and the program runs on flash memory. When there is no human reference, the system's sampling and control frequency is set to 20kHz. The DC bus voltage is set to 80V. The phase current waveform is sampled using a current probe. Since electromagnetic torque and stator flux linkage are difficult to measure directly, their waveforms are calculated based on the stator current ADC sampling values ​​and output to an oscilloscope via an external DAC module DAC81408. It should be noted that the innovation of this invention lies in verifying the proposed observation effect; the observation method proposed in this invention can also be ported to other hardware platforms.

[0129] The electromagnetic torque reference value varies by 0.2 N·m at 200 r / min, because the stator inductance parameter L used in the stator current observation model under this condition... did and L qiq Relative to the permanent magnet flux linkage parameter ψ pm The values ​​are all very small, so the stator flux linkage reference value is always set to 0.08 Wb. However, when better performance is required, the stator flux linkage reference value should be specifically designed. In this case, an 80V DC bus voltage is sufficient to drive the actual electromagnetic torque to the reference value within one control cycle. For example... Figure 5 As shown, Figure 5 This section compares the torque step response performance of three deadbeat control methods when the electromagnetic torque reference value changes by 0.2 N·m. Specifically, in... Figures 5-9 In the table, (a) is conventional DB-DTFC (deadbeat-direct torque and flux linkage control), (b) is DB-DTFC based on flux difference, and (c) is Deadbeat-direct composite torque control.

[0130] like Figure 6 As shown, Figure 6 To compare the torque step response performance of three deadbeat control methods when the electromagnetic torque reference value changes by 0.8 N·m, the stator flux linkage reference value is also set to 0.08 Wb. Under this condition, the 80V DC bus voltage cannot support one-step deadbeat torque control. Finally, the actual electromagnetic torque is in (k+

[0131] 5) The reference value is reached at the point. At the same time, the stator flux remains constant during the transient process.

[0132] The stator flux linkage reference value changed by 0.005 Wb, and the result is as follows: Figure 7 As shown, the 80V DC bus voltage cannot support a one-step flux linkage response; the actual stator flux linkage reaches the reference value at point (k+5). During the transient process, the electromagnetic torque first decreases and then rapidly recovers. The results show that all three deadbeat control methods can independently control the electromagnetic torque and stator flux linkage.

[0133] The velocity step result is as follows Figure 8 As shown, the rotor reference speed varies from 500 to 1000 r / min. The load torque remains around 2 N·m.

[0134] To further verify the flux linkage control performance of the proposed method, flux linkage weakening experiments were conducted. The experimental results are as follows: Figure 9 As shown. According to the parameters of the permanent magnet synchronous motor, when the DC bus voltage is 80V, the rotor speed can be further increased to 1200 r / min when the flux linkage is reduced to 0.07 Wb. Therefore, the reference value of rotor speed varies from 1000 to 1200 r / min, and the reference value of stator flux linkage varies from 0.08 to 0.07 Wb. The results show that both simplified methods can achieve the same flux linkage weakening performance as the traditional DB-DTFC.

[0135] In summary, this invention provides a method and apparatus for observing stator flux linkage and electromagnetic torque of a permanent magnet synchronous motor. First, a stator current observation model is designed based on the fundamental principles of disturbance observation and error feedback to achieve accurate stator current observation. Next, the observation error of the stator flux linkage is extracted from the error feedback of the stator current observation model. This observation error is then low-pass filtered to eliminate high-frequency interference before being compensated back into the stator flux linkage observation model, achieving accurate stator flux linkage observation. Finally, the electromagnetic torque is calculated based on the observed stator current and stator flux linkage. This invention can accurately observe the stator flux linkage and electromagnetic torque of a permanent magnet synchronous motor. Even if there are deviations between the actual parameters of the motor and the parameters used in the observation model, since stator flux linkage and electromagnetic torque are usually not directly measurable, the observation data of this invention can compensate for the measurement limitations, providing reliable motor state information for direct torque control of permanent magnet synchronous motors.

[0136] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for observing stator flux linkage of a permanent magnet synchronous motor, characterized in that, Includes the following steps: Obtain the measured values ​​of control voltage and stator current of the permanent magnet synchronous motor in the three-phase stationary coordinate system during the current control cycle; The measured values ​​of control voltage and stator current in the three-phase stationary coordinate system are transformed into the measured values ​​of control voltage and stator current in the synchronous rotating coordinate system, respectively. The measured values ​​of the control voltage and stator current are substituted into the stator current observation model to calculate the stator current observation value. The stator current observation model defines the relationship between the stator current observation value and the measured values ​​of the control voltage and stator current, the stator current observation error, and the system disturbance. The stator current observation error is determined based on the stator current observation value and the measured value of the stator current, and the system disturbance is obtained iteratively based on the stator current observation error. Error feedback of the stator current observation model is obtained based on the stator current observation value and the system disturbance; The stator flux observation error is extracted from the error feedback of the stator current observation model and then low-pass filtered. The stator flux linkage observation error after low-pass filtering is substituted into the stator flux linkage observation model to calculate the stator flux linkage observation value to achieve stator flux linkage observation. The stator flux linkage observation model defines the relationship between the stator flux linkage observation value, the stator flux linkage observation error, and the stator current observation value.

2. The method for observing stator flux linkage of a permanent magnet synchronous motor according to claim 1, characterized in that, Clarke transform and Park transform are used to transform the measured values ​​of control voltage and stator current in the three-phase stationary coordinate system into the measured values ​​of control voltage and stator current in the synchronous rotating coordinate system, respectively.

3. The method for observing stator flux linkage of a permanent magnet synchronous motor according to claim 1, characterized in that, The stator current observation model is as follows: Among them, i od and i oq For the stator current observation value, i d and i q The measured value of the stator current, u d and u q To control the voltage, e id and e iq For the stator current observation error, D d and D q For system disturbances, the subscripts d and q represent the d-axis and q-axis of the synchronous rotating coordinate system, respectively, and (k) and (k+1) represent the k-th and (k+1)-th control cycles, respectively. d and L q R is the stator inductance parameter used in the stator current observation model. s ψ is the stator resistance parameter used in the stator current observation model. pm ω is the permanent magnet flux linkage parameter used in the stator current observation model. r T is the electric angular velocity of the motor. s The control period is β1, which is the current error compensation coefficient. The stator current observation error is: The iterative formula for the system disturbance is: Where β2 is the perturbation iteration coefficient.

4. The method for observing stator flux linkage of a permanent magnet synchronous motor according to claim 3, characterized in that, The error feedback of the stator current observation model is: The observation error of the stator flux linkage is expressed as: The stator flux observation error is extracted from the error feedback of the stator current observation model described in equation (1), and low-pass filtered. Then, it is combined with equation (2) to obtain: Among them, e ψd and e ψq For the observation error of stator flux linkage, L d0 and L q0 ψ is the actual inductance value of the motor. pm0 is the actual permanent magnet flux linkage value of the motor, and LPF is the low-pass filter.

5. The method for observing stator flux linkage of a permanent magnet synchronous motor according to claim 4, characterized in that, The stator flux linkage observations are calculated as follows: Where, ψ do and ψ qo These are the stator flux linkage observations.

6. A method for observing the electromagnetic torque of a permanent magnet synchronous motor, characterized in that, Includes the following steps: Stator flux linkage observations were obtained using the method described in any one of claims 1 to 5; as well as, The electromagnetic torque observation value is calculated based on the stator current observation value and the stator flux linkage observation value.

7. The method for observing the electromagnetic torque of a permanent magnet synchronous motor according to claim 6, characterized in that, The electromagnetic torque observations are calculated as follows: Among them, T eo (k+1) Electromagnetic torque observation, p n This represents the number of pole pairs of the motor.

8. A device for observing the stator flux linkage of a permanent magnet synchronous motor, characterized in that, include: The acquisition module is used to acquire the measured values ​​of the control voltage and stator current of the permanent magnet synchronous motor in the three-phase stationary coordinate system during the current control cycle. The transformation module is used to transform the measured values ​​of control voltage and stator current in the three-phase stationary coordinate system into the measured values ​​of control voltage and stator current in the synchronous rotating coordinate system, respectively. A stator current observation model is used to calculate the stator current observation value based on the measured values ​​of the control voltage and stator current. The stator current observation model defines the relationship between the stator current observation value and the measured values ​​of the control voltage and stator current, the stator current observation error, and the system disturbance. The stator current observation error is determined based on the stator current observation value and the measured value of the stator current, and the system disturbance is obtained iteratively based on the stator current observation error. An error feedback module is used to obtain error feedback of the stator current observation model based on the stator current observation value and the system disturbance; The extraction module is used to extract the observation error of the stator flux linkage from the error feedback of the stator current observation model and perform low-pass filtering; A stator flux linkage observation model is used to calculate the stator flux linkage observation value based on the observation error of the stator flux linkage after low-pass filtering in order to realize the observation of the stator flux linkage. The stator flux linkage observation model defines the relationship between the stator flux linkage observation value, the stator flux linkage observation error, and the stator current observation value.

9. A permanent magnet synchronous motor electromagnetic torque observation device, characterized in that, The invention includes an electromagnetic torque observation model and a permanent magnet synchronous motor stator flux linkage observation device according to claim 8. The electromagnetic torque observation model is used to calculate the electromagnetic torque observation value based on the stator flux linkage observation value and the stator current observation value obtained by the permanent magnet synchronous motor stator flux linkage observation device.

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