A method for measuring direct-axis inductance of a memory motor during magnetic adjustment

Abstract

The invention discloses a method for measuring the direct-axis inductance of a memory motor during magnetic adjustment. The method obtains the change of the permanent magnetic flux linkage of the memory motor during magnetic adjustment by approximating the magnetization curve, improves the traditional voltage pulse injection method, and makes it possible to calculate the direct-axis inductance value of the memory motor. The method can accurately measure the change value of the direct-axis inductance of the memory motor during magnetic adjustment, and provide data support for the establishment of a memory motor model. The method solves the problem that the direct-axis inductance parameter of the memory motor during magnetic adjustment in the prior art is difficult to measure.

Description

Technical Field

[0001] The invention belongs to the field of motor testing, and in particular relates to a method for measuring direct-axis inductance of a memory motor during magnetic modulation. Background Art

[0002] Compared with ordinary permanent magnet synchronous motors, memory motors (MM) have variable permanent magnet flux, which has attracted the attention and recognition of scholars at home and abroad. Usually, direct axis (d axis) pulse current is applied to change its permanent magnet flux. When running at low speed, it runs in a high magnetization state (MS), which can generate large torque and is suitable for heavy load occasions; when running at high speed, it runs in a low magnetization state, which can widen the speed operating range.

[0003] When this type of motor is magnetically adjusted, the amplitude of the direct-axis pulse current is very large, about 3 to 4 times the rated current, and the direct-axis inductance changes greatly. Therefore, in order to achieve high-precision control, it is necessary to measure the inductance parameter value during the magnetic adjustment period in advance. When the memory motor is magnetically adjusted, the permanent magnet flux will change accordingly, and it is difficult to calculate the inductance value using traditional methods. Therefore, it is in line with practical needs to propose a method that can simply measure the direct-axis inductance parameters of the memory motor during magnetic adjustment.

[0004] In view of the above problems, a method for measuring the direct-axis inductance of a memory motor during magnetic modulation is proposed. Summary of the invention

[0005] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a method for measuring the direct-axis inductance of a memory motor during magnetic modulation, thereby solving the problem in the prior art that the direct-axis inductance parameters of a memory motor during magnetic modulation are difficult to measure.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for measuring the direct-axis inductance of a memory motor during magnetic modulation comprises the following steps:

[0008] S1. Measure the magnetization curve of the memory motor;

[0009] S2, measure the motor phase resistance R;

[0010] S3. Determine the initial magnetization state MS of the magnetic modulation operation to be measured i and the magnetization state MS after magnetic tuning j , according to the magnetization curve, adjust the motor to the initial magnetization state MS i The current i that needs to be applied d_i , and the current i required for the magnetic modulation operation d_j ;

[0011] S4, lock the motor rotor and apply a positive and negative symmetrical square wave voltage u to the d-axis. d , so that the direct axis current i d Growth d_i , adjust the motor magnetization state to MS i , complete the initialization magnetic adjustment;

[0012] S5. Apply a positive and negative symmetrical square wave voltage u on the d axis d , so that the d-axis current i d Growth to i d_j Then it decreases to 0 and records the voltage u d , current i d The curve of change over time t completes the magnetic adjustment operation to be measured;

[0013] S6. Combine the magnetization curve to determine the change curve of permanent magnetic flux during magnetic modulation and the relationship ψ PM (i d );

[0014] S7. Using the recorded data, calculate the inductance L during the magnetic modulation period. d (i d ) in MS i To MS j The relationship between the period and the current:

[0015]

[0016] S8. Repeat S3 to S7 to measure the change in d-axis inductance during different magnetizing operations.

[0017] Furthermore, the magnetization curve in S1 is the corresponding relationship between the d-axis pulse current amplitude and the permanent magnet flux linkage, including the magnetization curve for magnetization and the demagnetization curve for magnetization, which are expressed by functions as follows:

[0018]

[0019] Furthermore, the purpose of initializing the magnetization state in S3 is to magnetize the motor to MS i , so that in the next step the MS i To MS j Magnetic adjustment operation.

[0020] Furthermore, during the magnetic adjustment period ψ in S6 PM (i d ) The acquisition of the relation includes the following steps:

[0021] S6.1, Assume that the magnetic adjustment operation to be tested is magnetization, if i d_i >0, that is, the initialization magnetic adjustment operation is magnetization. According to the magnetization characteristics of the memory motor, it is approximately believed that the change relationship of the permanent magnet flux during the magnetic adjustment period to be tested is:

[0022]

[0023] If i d_i <0, that is, the initialization magnetization operation is demagnetization, then the change relationship of the permanent magnet flux linkage during the magnetization period to be tested is considered to be:

[0024]

[0025] S6.2, Assume that the magnetic adjustment operation to be tested is demagnetization, if i d_i >0, that is, the initialization magnetic adjustment operation is magnetization. According to the magnetization characteristics of the memory motor, it can be approximately considered that the change relationship of the permanent magnet flux during the magnetic adjustment period to be tested is:

[0026]

[0027] If i d_i <0, that is, the initialization magnetization operation is demagnetization, then the change relationship of the permanent magnet flux linkage during the magnetization period to be tested is considered to be:

[0028]

[0029] Furthermore, obtaining the inductance in S7 includes the following steps:

[0030] S7.1, obtaining the d-axis voltage of the memory motor;

[0031] The d-axis voltage equation of the memory motor is;

[0032]

[0033] In the formula, ω e is the rotor electrical angular velocity, ψ d is the d-axis magnetic flux;

[0034] ψ d =L d (i d )i d +ψ PM (i d ⑧

[0035] S7.2, solve the d-axis inductance value;

[0036] The motor rotor is fixed, that is, ω e is 0, formula ③ can be simplified to calculate the d-axis inductance value:

[0037]

[0038] Where ψ PM (i d ) is obtained by formula ②-⑤

[0039] Beneficial effects of the present invention:

[0040] 1. The method for measuring the direct-axis inductance of a memory motor during magnetic modulation proposed in the present invention obtains the change in the permanent magnet flux linkage of the memory motor during magnetic modulation by approximating the magnetization curve, improves the traditional voltage pulse injection method so that the direct-axis inductance value of the memory motor can be calculated, and can accurately measure the change in the direct-axis inductance value of the memory motor during magnetic modulation, providing data support for the establishment of a memory motor model. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 is a schematic diagram of a magnetization curve of a memory motor according to an embodiment of the present invention;

[0043] Figure 2 is a voltage and current waveform diagram when measuring inductance according to an embodiment of the present invention;

[0044] Figure 3 1 is a magnetization and demagnetization current waveform diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] A method for measuring the direct-axis inductance of a memory motor during magnetic modulation specifically comprises the following steps:

[0047] S1. Measure the magnetization curve of the memory motor;

[0048] The magnetization curve is the corresponding relationship between the d-axis pulse current amplitude and the permanent magnet flux, such as Figure 1 As shown, it includes the magnetization curve and the demagnetization curve, which are expressed by functions as follows:

[0049]

[0050] Specifically, three magnetization states MS1, MS2, and MS3 are selected as the operating magnetization states of the example motor;

[0051] S2, measure the motor phase resistance R;

[0052] S3. Determine the initial magnetization state MS of the magnetic modulation operation to be measured i (corresponding to magnetic flux ψ PM_i ) and the magnetization state MS after magnetic modulation j (corresponding to magnetic flux ψ PM_j ), according to the magnetization curve, the motor is adjusted to the initial magnetization state MS i The current i that needs to be applied d_i , and the current i required for the magnetic modulation operation d_j ;

[0053] The purpose of magnetization state initialization is to magnetize the motor to MS i , so that in the next step the MS i To MS j The magnetic adjustment operation, such as Figure 2 As shown, before measuring, apply i d0 , regardless of the current magnetization level of the motor, it will be demagnetized to MS3;

[0054] S4, lock the motor rotor and apply a positive and negative symmetrical square wave voltage u to the d-axis. d , so that the direct axis current i d Growth d_i , adjust the motor magnetization state to MS i , complete the initialization magnetic adjustment;

[0055] S5. Apply a positive and negative symmetrical square wave voltage u on the d axis d , so that the d-axis current i d Growth to i d_j Then it decreases to 0 and records the voltage u d , current i d The curve of change over time t completes the magnetic adjustment operation to be measured;

[0056] S6. Combine the magnetization curve to determine the change curve of permanent magnetic flux during magnetic modulation and the relationship ψ PM (i d );

[0057] S6.1, Assume that the magnetic adjustment operation to be tested is magnetization, if i d_i >0, that is, the initialization magnetic adjustment operation is magnetization. According to the magnetization characteristics of the memory motor, it is approximately believed that the change relationship of the permanent magnet flux during the magnetic adjustment period to be tested is:

[0058]

[0059] like Figure 2 As shown in the figure, when measuring the magnetic adjustment operation from MS2 to MS1, the change of permanent magnetic flux satisfies formula ②. At this time, i d_i =id1 ,i d_j =i d2 ; Figure 3 The rising and falling stages of magnetizing and demagnetizing current are shown. It is generally believed that the permanent magnet flux of the motor remains basically unchanged during the current falling stage.

[0060] If i d_i <0, that is, the initialization magnetization operation is demagnetization, then the change relationship of the permanent magnet flux linkage during the magnetization period to be tested is considered to be:

[0061]

[0062] like Figure 2 As shown, when measuring the magnetic adjustment operation from MS3 to MS2, the change of permanent magnetic flux meets formula ③;

[0063] S6.2, Assume that the magnetic adjustment operation to be tested is demagnetization, if i d_i >0, that is, the initialization magnetic adjustment operation is magnetization. According to the magnetization characteristics of the memory motor, it can be approximately considered that the change relationship of the permanent magnet flux during the magnetic adjustment period to be tested is:

[0064]

[0065] If i d_i <0, that is, the initialization magnetization operation is demagnetization, then the change relationship of the permanent magnet flux linkage during the magnetization period to be tested is considered to be:

[0066]

[0067] S7. Using the recorded data, calculate the inductance L during the magnetic modulation period. d (i d ) in MS i To MS j The relationship between the period and the current:

[0068]

[0069] The acquisition of inductance mainly includes the following steps:

[0070] S7.1, obtaining the d-axis voltage of the memory motor;

[0071] The d-axis voltage equation of the memory motor is;

[0072]

[0073] In the formula, ω e is the rotor electrical angular velocity, ψ d is the d-axis magnetic flux;

[0074] ψ d =L d (id )i d +ψ PM (i d ⑧

[0075] S7.2, solve the d-axis inductance value;

[0076] The motor rotor is fixed, that is, ω e is 0, formula ③ can be simplified to calculate the d-axis inductance value:

[0077]

[0078] Where ψ PM (i d ) is obtained by formula ②-⑤;

[0079] S8. Repeat S3 to S7 to measure the change in d-axis inductance during different magnetizing operations.

[0080] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0081] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for measuring the direct-axis inductance of a memory motor during magnetic modulation, characterized in that: The steps include: S1. Measure the magnetization curve of the memory motor; S2, measure the motor phase resistance R; S3. Determine the initial magnetization state MS of the magnetic modulation operation to be measured i and the magnetization state MS after magnetic tuning j , according to the magnetization curve, adjust the motor to the initial magnetization state MS i The current i that needs to be applied d_i , and the current i required for the magnetic modulation operation d_j ; S4, lock the motor rotor and apply a positive and negative symmetrical square wave voltage u to the d-axis. d , so that the direct axis current i d Growth d_i , adjust the motor magnetization state to MS i , complete the initialization magnetic adjustment; S5. Apply a positive and negative symmetrical square wave voltage u on the d axis d , so that the d-axis current i d Growth to i d_j Then it decreases to 0 and records the voltage u d , current i d The curve of change over time t completes the magnetic adjustment operation to be measured; S6. Combine the magnetization curve to determine the change curve of permanent magnetic flux during magnetic modulation and the relationship ψ PM (i d ); S7. Using the recorded data, calculate the inductance L during the magnetic modulation period. d (i d ) in MS i To MS j The relationship between the period and the current: S8. Repeat S3 to S7 to measure the change in d-axis inductance during different magnetizing operations.

2. The method for measuring the direct-axis inductance of a memory motor during magnetic modulation according to claim 1, characterized in that: The magnetization curve in S1 is the corresponding relationship between the d-axis pulse current amplitude and the permanent magnet flux linkage, including the magnetization curve and the demagnetization curve, which are expressed by functions as follows:

3. The method for measuring the direct-axis inductance of a memory motor during magnetic modulation according to claim 1, characterized in that: The purpose of initializing the magnetization state in S3 is to magnetize the motor to MS i , so that in the next step the MS i To MS j Magnetic adjustment operation.

4. The method for measuring the direct-axis inductance of a memory motor during magnetic modulation according to claim 1, characterized in that: During the magnetic adjustment period in S6 PM (i d ) The acquisition of the relation includes the following steps: S6.1, Assume that the magnetic adjustment operation to be tested is magnetization, if i d_i >0, that is, the initialization magnetic adjustment operation is magnetization. According to the magnetization characteristics of the memory motor, it is approximately believed that the change relationship of the permanent magnet flux during the magnetic adjustment period to be tested is: If i d_i <0, that is, the initialization magnetization operation is demagnetization, then the change relationship of the permanent magnet flux linkage during the magnetization period to be tested is considered to be: S6.2, Assume that the magnetic adjustment operation to be tested is demagnetization, if i d_i >0, that is, the initialization magnetic adjustment operation is magnetization. According to the magnetization characteristics of the memory motor, it can be approximately considered that the change relationship of the permanent magnet flux during the magnetic adjustment period to be tested is: If i d_i <0, that is, the initialization magnetization operation is demagnetization, then the change relationship of the permanent magnet flux linkage during the magnetization period to be tested is considered to be:

5. The method for measuring the direct-axis inductance of a memory motor during magnetic modulation according to claim 4, characterized in that: The acquisition of inductance in S7 includes the following steps: S7.1, obtaining the d-axis voltage of the memory motor; The d-axis voltage equation of the memory motor is; In the formula, ω e is the rotor electrical angular velocity, ψ d is the d-axis magnetic flux; ψ d =L d (i d )i d +ψ PM (i d )⑧; S7.2, solve the d-axis inductance value; The motor rotor is fixed, that is, ω e is 0, formula ③ can be simplified to calculate the d-axis inductance value: Where ψ PM (i d ) is obtained through formulas ②—⑤.

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