A method for suppressing magnetic charging speed fluctuation of a high saliency ratio memory motor

Abstract

The application discloses a high saliency ratio memory motor magnetizing speed fluctuation suppression method and relates to the technical field of motor control. The application discloses a high saliency ratio memory motor magnetizing speed fluctuation suppression method. In view of the problem that a large negative torque occurs when a high saliency ratio memory motor is magnetized, thus causing a great speed fluctuation, the method of the application uses a disturbance torque observer to observe the electromagnetic torque of the motor, predicts the time when the negative electromagnetic torque occurs, reverses the output of the speed controller at the moment, and uses the output as a quadrature axis current reference value, so that a large negative torque is avoided when the motor is magnetized, and the speed fluctuation is greatly reduced. The high saliency ratio memory motor magnetizing speed fluctuation suppression method can observe when the quadrature axis current should be reversed on line and is not affected by the change of motor parameters.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, specifically to a method for suppressing magnetization speed fluctuations in a high saliency pole rate memory motor. Background Technology

[0002] Memory motors (MMs) contain low-coercivity permanent magnets. Their magnetization state (MS) can be adjusted by applying a direct-axis (d-axis) pulse current, thereby changing the permanent magnet flux linkage. Therefore, by flexibly adjusting the permanent magnet flux linkage, memory motors can operate in various applications. Typically, at low speeds, the permanent magnet flux linkage is increased to generate high torque; at high speeds, the permanent magnet flux linkage is decreased to reduce field weakening losses and achieve wide-speed operation. However, adjusting the magnetization state of a memory motor requires applying a large d-axis pulse current, approximately 2-3 times the rated current, which can cause significant speed fluctuations. For high-salient-pole memory motors, the reluctance torque component is large; applying a magnetizing d-axis current pulse will result in negative electromagnetic torque, leading to very large speed fluctuations when using traditional control methods under load. Summary of the Invention

[0003] The purpose of this invention is to provide a method for suppressing the magnetization speed fluctuation of a high salient pole ratio memory motor. By using a disturbance observer to observe the time when the negative torque occurs, the time when the negative torque occurs can be greatly reduced by reversing the quadrature axis (q-axis) current, thereby greatly reducing speed fluctuation.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for suppressing magnetization speed fluctuations in a high saliency pole rate memory motor, comprising:

[0005] Define a q-axis current reverse flag CRflag to determine whether the q-axis current needs to be reversed during magnetization to avoid negative electromagnetic torque, thereby reducing motor speed fluctuations during magnetization. When CRflag = 1, it indicates that the speed controller output needs to be reversed; when CRflag = 0, it does not need to be reversed.

[0006] A judgment enable flag, Eflag, is defined to prevent CRflag from being incorrectly set during magnetization; Eflag = 1 indicates that CRflag judgment is enabled, that is, when the switching condition for electromagnetic torque is met. When Eflag = 0, CRflag will change from 0 to 1 or from 1 to 0; when Eflag = 0, CRflag will remain unchanged during this period.

[0007] The electromagnetic torque during magnetization is estimated using a disturbance torque observer.

[0008] During non-magnetic adjustment periods, CRflag = 0, Eflag = 1;

[0009] During magnetization, in the current rising phase, when When the current decreases, CRflag is set to 1, and the judgment enable flag is turned off, i.e., Eflag is set to 0, until the current decreases, when Eflag is set to 1 again.

[0010] During magnetization, in the current decreasing phase, when When the magnetization is complete, CRflag is set to 0, and the judgment enable flag is turned off, i.e., Eflag is set to 0, until the magnetization is completed, and then Eflag is set to 1 again;

[0011] During the magnetization process, when CRflag=1, the output value of the speed controller needs to be reversed and used as a reference value output, that is, the q-axis current is reversed to ensure that the motor output torque is non-negative.

[0012] Furthermore, the electromagnetic torque during magnetization is estimated. Specifically, it includes the following:

[0013] The electromagnetic torque of the memory motor is:

[0014]

[0015] In the formula, T e For electromagnetic torque, T PM For the permanent magnet torque component, T RT Let p be the reluctance torque component, p be the number of pole pairs, and i be the number of reluctance torque components. d and i q These are the dq-axis currents, L d and L q These are the d-q axis inductances, ψ PM (i d ) is a variable permanent magnet flux linkage;

[0016] Considering the periods of magnetization and non-magnetization, the mechanical equations of the memory motor can be written as follows:

[0017]

[0018] In the formula, ω m Let B be the mechanical angular velocity, B be the coefficient of friction, J be the moment of inertia, and T be the moment of rotation. LD For the defined disturbance torque, T * This is the torque reference value;

[0019] T * Specifically represented as

[0020]

[0021] Disturbance torque T LD It can be represented as:

[0022]

[0023] In the formula, T L This is the load torque;

[0024] The disturbance torque observer is specifically designed as follows:

[0025]

[0026] Subtracting equation (2) from equation (5) yields the speed error. The equation is:

[0027]

[0028] Using the super-twist algorithm, the observed disturbance torque can be expressed as:

[0029]

[0030] In the formula, k1 and k2 are positive constants;

[0031] Electromagnetic torque observation during magnetization It can be represented as:

[0032]

[0033] Since the magnetization time is very short, the load torque can be considered to be the same as the value during the non-magnetization period, and thus we can obtain...

[0034]

[0035] The present invention has at least the following beneficial effects:

[0036] 1. The method of the present invention uses disturbance torque to observe the reverse indication of quadrature-axis current, which is not affected by changes in motor parameters compared to experimental measurement methods;

[0037] 2. Compared with traditional methods, the method of the present invention can greatly reduce the speed fluctuation of the magnetizing motor by using cross-axis current reverse control based on the disturbance observer.

[0038] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0039] Figure 1 This is a block diagram of the high salient pole ratio memory motor speed control system of the present invention;

[0040] Figure 2 This is the online observation process of the cross-axis current reverse flag bit of the present invention;

[0041] Figure 3 This is a structural diagram of the quadrature-axis current reverse control method based on a disturbance observer according to the present invention;

[0042] Figure 4 This is a structural diagram of the disturbance observer of the present invention;

[0043] Figure 5 The present invention addresses the rotational speed fluctuation during magnetization using traditional PI control.

[0044] Figure 6 This invention describes the magnetization current waveform using conventional PI control.

[0045] Figure 7 This is the magnetization speed waveform of the present invention using cross-axis current reverse control;

[0046] Figure 8 This is the magnetization current waveform of the present invention, which uses cross-axis current reverse control. Detailed Implementation

[0047] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0048] Please see Figure 1-5 This invention provides a technical solution: a method for suppressing magnetization speed fluctuations in a high saliency pole ratio memory motor, the specific steps of which are as follows:

[0049] S1. Define the q-axis current reverse flag CRflag to determine whether the q-axis current needs to be reversed during magnetization to avoid negative electromagnetic torque, thereby reducing magnetization speed fluctuations. When CRflag = 1, it means that the output of the speed controller needs to be reversed; when CRflag = 0, it does not need to be reversed.

[0050] S2. Define a judgment enable flag Eflag to prevent CRflag from being incorrectly set during magnetization; when Eflag = 1, it indicates that CRflag judgment is enabled, that is, when the switching condition is met. When Eflag = 0, CRflag will change from 0 to 1 or from 1 to 0; when Eflag = 0, CRflag will remain unchanged during this period.

[0051] S3. Use a disturbance torque observer to estimate the electromagnetic torque during magnetization, denoted as...

[0052] S4. During the non-magnetic adjustment period, CRflag = 0 and Eflag = 1;

[0053] S5. During magnetization, in the current rising phase, when When the current decreases, CRflag is set to 1, and the judgment enable flag is turned off, i.e., Eflag is set to 0, until the current decreases, when Eflag is set to 1 again.

[0054] S6. During magnetization, in the current decreasing phase, when When the magnetization is complete, CRflag is set to 0, and the judgment enable flag is turned off, i.e., Eflag is set to 0, until the magnetization is completed, and then Eflag is set to 1 again;

[0055] Specifically, the process of generating the magnetizing current, such as Figure 1 As shown, the magnetization state controller generates a permanent magnet flux reference value based on the current magnetization state and rotation speed, and the pulse current generator generates a corresponding magnetization adjustment current based on this reference value.

[0056] The specific process of CRflag observation described above, such as Figure 2 As shown;

[0057] S7. During the magnetic adjustment process, when CRflag = 1, the output value of the speed controller needs to be reversed and used as a reference value output, that is, the q-axis current is reversed to ensure that the motor output torque is non-negative.

[0058] Figure 3 The diagram shows the q-axis current reverse control structure based on the disturbance observer of the present invention. When CRflag is set to 1, the output of the speed controller is reversed and used as a reference value, thereby obtaining the reversed q-axis current.

[0059] Furthermore, the electromagnetic torque during magnetization is estimated. Specifically, it includes the following:

[0060] S5.1, The electromagnetic torque of the memory motor is:

[0061]

[0062] In the formula, T e For electromagnetic torque, T PM For the permanent magnet torque component, T RT Let p be the reluctance torque component, p be the number of pole pairs, and i be the number of reluctance torque components. d and i q These are the dq-axis currents, L d and L q These are the d-q axis inductances, ψ PM (i d ) is a variable permanent magnet flux linkage;

[0063] S5.2. Considering the periods of magnetization adjustment and non-magnetization adjustment, the mechanical equation of the memory motor can be written as:

[0064]

[0065] In the formula, ω m Let B be the mechanical angular velocity, B be the coefficient of friction, J be the moment of inertia, and T be the moment of rotation. LD For the defined disturbance torque, T * As a torque reference value, it can be expressed as:

[0066]

[0067] Disturbance torque T LD It can be represented as:

[0068]

[0069] In the formula, T L This is the load torque;

[0070] S5.3, Design the disturbance torque observer as follows:

[0071]

[0072] Subtracting equation (2) from equation (5) yields the speed error. The equation is:

[0073]

[0074] Using the super-twist algorithm, the observed disturbance torque can be expressed as:

[0075]

[0076] In the formula, k1 and k2 are positive constants;

[0077] The super-twist algorithm is a commonly used high-order sliding mode control algorithm in existing technologies. It does not require the differentiation of sliding mode variables, and has the advantages of traditional sliding mode control while effectively suppressing chattering.

[0078] The structure of the super-torsional sliding mode torque observer is as follows: Figure 4 As shown:

[0079] S5.4 Electromagnetic torque observation during magnetization. It can be represented as:

[0080]

[0081] Since the magnetization time is very short, the load torque can be considered to be the same as the value during the non-magnetization period, and thus:

[0082]

[0083] Figure 5-6To illustrate the rotational speed and current waveform during magnetization using a traditional PI speed controller, during magnetization, due to i d Increase, motor L d Less than L q As the electromagnetic torque decreases, the speed drops. When using traditional PI control, the speed controller outputs a larger q-axis current reference value in an attempt to maintain a constant speed. However, when i d When the value is large, the electromagnetic torque is negative, i q Although the limit value was reached, the electromagnetic torque was still negative and the speed fluctuated greatly. As can be seen from the figure, the speed fluctuation reached 110 rpm (27.5% of the reference speed). Figure 7-8 The diagram shows the rotational speed and current waveforms during magnetization using the reverse q-axis current control method of this invention. It can be seen that by using reverse q-axis current control, the q-axis current can change from a positive value to a negative value during magnetization, thereby avoiding negative torque and greatly reducing speed fluctuations, which are only about 20 rpm (5% of the reference speed).

[0084] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0085] For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on," "mounted on," "fixed to," or "set on" another element, it may be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0087] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A method for suppressing magnetization speed fluctuations in a high saliency pole rate memory motor, characterized in that, include: Define a q-axis (i.e., quadrature axis) current reversal flag CRflag to determine whether the q-axis current needs to be reversed during magnetization to avoid negative electromagnetic torque, thereby reducing motor speed fluctuations during magnetization. When CRflag = 1, it indicates that the speed controller output needs to be reversed; when CRflag = 0, it does not need to be reversed. A judgment enable flag, Eflag, is defined to prevent CRflag from being incorrectly set during magnetization; Eflag = 1 indicates that CRflag judgment is enabled, that is, when the switching condition for electromagnetic torque is met. When Eflag = 0, CRflag will change from 0 to 1 or from 1 to 0; when Eflag = 0, CRflag will remain unchanged during this period. The electromagnetic torque during magnetization is estimated using a disturbance torque observer. During non-magnetic adjustment periods, CRflag = 0, Eflag = 1; During magnetization, in the current rising phase, when When the current decreases, CRflag is set to 1, and the judgment enable flag is turned off, i.e., Eflag is set to 0, until the current decreases, when Eflag is set to 1 again. During magnetization, in the current decreasing phase, when When the magnetization is complete, CRflag is set to 0, and the judgment enable flag is turned off, i.e., Eflag is set to 0, until the magnetization is completed, and then Eflag is set to 1 again; During the magnetization process, when CRflag=1, the output value of the speed controller needs to be reversed and used as a reference value output, that is, the q-axis current is reversed to ensure that the motor output torque is non-negative.

2. The method for suppressing magnetization speed fluctuations in a high saliency pole ratio memory motor according to claim 1, characterized in that, Estimate the electromagnetic torque during magnetization. The specific steps include the following: The electromagnetic torque of the memory motor is: In the formula, T e For electromagnetic torque, T PM For the permanent magnet torque component, T RT Let p be the reluctance torque component, p be the number of pole pairs, and i be the number of reluctance torque components. d and i q These are the dq-axis currents, L d and L q These are the d-q axis inductances, ψ PM (i d ) is a variable permanent magnet flux linkage; Considering the periods of magnetization and non-magnetization, the mechanical equation of the memory motor is: In the formula, ω m Let B be the mechanical angular velocity, B be the coefficient of friction, J be the moment of inertia, and T be the moment of rotation. LD For the defined disturbance torque, T * This is a torque reference value; T * Specifically, it is expressed as follows: Disturbance torque T LD Specifically, it is expressed as follows: In the formula, T L This is the load torque; The disturbance torque observer is specifically designed as follows: Subtracting equation (2) from equation (5) yields the speed error. The equation is: Using the super-twist algorithm, the observed disturbance torque is expressed as: In the formula, k1 and k2 are positive constants; Electromagnetic torque observation during magnetization Specifically, it is expressed as follows: Since the magnetization time is very short, the load torque can be considered to be the same as the value during the non-magnetization period, and thus: Substituting equation (9) into equation (8) yields the observed electromagnetic torque value.

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