Motor rotor initial position identification method, system and device and storage medium

Abstract

The invention discloses a motor rotor initial position identification method, system and device and a storage medium, and relates to the field of motor control, and the method comprises the steps: injecting a pulse voltage signal into a stator of a motor, enabling a stator current to generate a stator magnetic field, and enabling a rotor permanent magnet to generate a rotor magnetic field; calculating current response change factors of the stator magnetic field and the rotor magnetic field in different opposite directions within a preset time by controlling the direction and the size of the stator current; and identifying the initial position of the motor rotor according to the current response change factors in different relative directions. By injecting a pulse voltage signal into a motor stator, the direction and the magnitude of stator current are accurately controlled, so that the interaction between a stator magnetic field and a rotor magnetic field can be measured in different opposite directions. The interaction is represented by a current response change factor, so that the initial position of the motor rotor is accurately identified.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a method, system, device and storage medium for identifying the initial position of a motor rotor. Background Art

[0002] In a permanent magnet synchronous motor, accurate knowledge of the rotor position is crucial for motor control. The initial position of the rotor is usually unknown when the motor starts. In modern industry, the common method for identifying the initial position of the motor rotor is the high-frequency square wave voltage injection method (HFI), which injects a high-frequency square wave voltage into the motor stator winding to obtain the current response and then estimate the rotor position.

[0003] Although the high-frequency square wave voltage injection method is widely used in industry, it has problems in identifying the initial position of the rotor. This method has multiple convergence points that require polarity identification. The current polarity identification scheme cannot accurately identify the magnetic pole polarity, and there is a risk of causing the motor to reverse. The current method directly compares the current response corresponding to the two injected voltages. If the current response is small or the difference between the two injected current responses is small, as well as current fluctuations or sampling deviations, it is easy to cause polarity identification errors. Summary of the invention

[0004] The main purpose of the present invention is to provide a method, system, device and storage medium for identifying the initial position of a motor rotor, which can accurately control the direction and magnitude of the stator current by injecting a pulse voltage signal into the motor stator, so as to measure the interaction between the stator magnetic field and the rotor magnetic field in different relative directions. This interaction is characterized by a current response change factor, thereby realizing accurate identification of the initial position of the motor rotor.

[0005] In order to achieve the above objectives, the present application provides the following technical solutions:

[0006] According to a first aspect of an embodiment of the present application, a method for identifying an initial position of a motor rotor is provided, the method comprising:

[0007] A pulse voltage signal is injected into the stator of the motor so that the stator current generates a stator magnetic field, and the rotor permanent magnet generates a rotor magnetic field;

[0008] By controlling the direction and magnitude of the stator current, a current response variation factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time is calculated;

[0009] The initial position of the motor rotor is identified according to the current response variation factors in the different relative directions.

[0010] Optionally, when the stator magnetic field and the rotor magnetic field have the same direction, calculating the current response change factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time by controlling the direction and magnitude of the stator current includes:

[0011] The stator current is gradually reduced to 0 according to the set gradient, and then increased in the reverse direction according to the set gradient to the set current negative value and maintained for the set stable time;

[0012] A current response variation factor of the stator current within the predetermined time is calculated.

[0013] Optionally, when the stator magnetic field is in opposite directions to the rotor magnetic field, calculating the current response change factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time by controlling the direction and magnitude of the stator current includes:

[0014] The stator current is gradually reduced to 0 according to the set gradient, and then continued to increase to the set current positive value according to the set gradient and maintained for the set stable time;

[0015] A current response variation factor of the stator current within the predetermined time is calculated.

[0016] Optionally, the calculating the current response change factor of the stator current within the predetermined time includes:

[0017] Measuring the direct-axis high-frequency response current of each sampling point within the predetermined time;

[0018] Calculate the cumulative value of the direct-axis high-frequency response current of all sampling points at each measurement moment;

[0019] The current response average value is obtained according to the direct-axis high-frequency response current cumulative value of all sampling points and the number of the sampling points, which is used as the current response variation factor.

[0020] Optionally, identifying the initial position of the motor rotor according to the current response variation factor in the different relative directions includes:

[0021] Determine the absolute value of the current response change factor when the stator magnetic field and the rotor magnetic field have the same direction as the first current factor;

[0022] Determine the absolute value of the current response change factor when the stator magnetic field and the rotor magnetic field are in opposite directions as a second current factor;

[0023] If the first current factor is greater than the second current factor, the initial position of the motor rotor is the N pole;

[0024] If the first current factor is smaller than the second current factor, the initial position of the motor rotor is the S pole.

[0025] Optionally, the method further includes: controlling the direction and magnitude of the stator current so that the stator magnetic field has the same direction as the rotor magnetic field; specifically including:

[0026] Converting the stator current from a three-phase coordinate system to a two-phase rotating coordinate system, wherein the stator magnetic field is aligned with the rotor magnetic field; wherein the stator current is decomposed into a d-axis component and a q-axis component that are parallel and perpendicular to the rotor magnetic field, respectively;

[0027] Calculate the d-axis current component and the q-axis current component according to the motor control requirements and generate corresponding control signals;

[0028] Convert the voltage components in the two-phase rotating coordinate system back to the three-phase coordinate system to obtain the three-phase voltage components;

[0029] Generate pulse width modulation signals according to three-phase voltage components to control motor phase currents;

[0030] The actual phase current of the motor is monitored in real time, and the d-axis current component is aligned with the rotor magnetic field by adjusting the pulse width modulation signal. The q-axis current component is used to control the torque of the motor.

[0031] Optionally, the method further includes: controlling the direction and magnitude of the stator current so that the stator magnetic field is opposite to the rotor magnetic field; specifically including:

[0032] Converting the stator current from a three-phase coordinate system to a two-phase rotating coordinate system, wherein the stator magnetic field is aligned with the rotor magnetic field; wherein the stator current is decomposed into a d-axis component and a q-axis component that are parallel and perpendicular to the rotor magnetic field, respectively;

[0033] The d-axis current component and the q-axis current component are calculated according to the requirements of the motor control; wherein the d-axis current component is adjusted so that the stator magnetic field and the rotor magnetic field are in opposite directions;

[0034] Generate a corresponding control signal according to the calculated d-axis current component and q-axis current component; wherein the d-axis control signal is adjusted to be opposite to the direction of the rotor magnetic field;

[0035] Convert the voltage components in the two-phase rotating coordinate system back to the three-phase coordinate system to obtain the three-phase voltage components;

[0036] Generate pulse width modulation signals according to three-phase voltage components to control motor phase currents;

[0037] The actual phase current of the motor is monitored in real time, and the pulse width modulation signal is adjusted so that the d-axis current component is opposite to the rotor magnetic field.

[0038] According to a second aspect of an embodiment of the present application, a motor rotor initial position identification system is provided, the system comprising:

[0039] A magnetic field generating module is used to inject a pulse voltage signal into the stator of the motor so that the stator current generates a stator magnetic field, and the rotor permanent magnet generates a rotor magnetic field;

[0040] A current response calculation module, used to calculate a current response variation factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time by controlling the direction and magnitude of the stator current;

[0041] The position identification module is used to identify the initial position of the motor rotor according to the current response change factor in the different relative directions.

[0042] According to a third aspect of an embodiment of the present application, an electronic device is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described in the first aspect above.

[0043] According to a fourth aspect of an embodiment of the present application, a computer-readable storage medium is provided, on which computer-readable instructions are stored. The computer-readable instructions can be executed by a processor to implement the method described in the first aspect above.

[0044] In summary, the embodiments of the present application provide a method, system, device and storage medium for identifying the initial position of a motor rotor. By injecting a pulse voltage signal into the stator of the motor, the stator current generates a stator magnetic field, and the rotor permanent magnet generates a rotor magnetic field; by controlling the direction and magnitude of the stator current, the current response change factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time is calculated; according to the current response change factor in different relative directions, the initial position of the motor rotor is identified. By injecting a pulse voltage signal into the stator of the motor, the direction and magnitude of the stator current are precisely controlled so as to measure the interaction between the stator magnetic field and the rotor magnetic field in different relative directions. This interaction is characterized by the current response change factor, thereby realizing accurate identification of the initial position of the motor rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] 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, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0046] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0047] Figure 1 A flow chart of a method for identifying the initial position of a motor rotor provided in an embodiment of the present application;

[0048] Figure 2a , Figure 2b , Figure 2c , Figure 2d A schematic diagram of the polarity discrimination principle provided in an embodiment of the present application;

[0049] Figure 3 A logic flow chart of the polarity discrimination system provided in the embodiment of the present application;

[0050] Figure 4 A schematic diagram of a trapezoidal wave current provided in an embodiment of the present application;

[0051] Figure 5 A schematic diagram of a motor rotor initial position identification system provided in an embodiment of the present application;

[0052] Figure 6 A structural diagram of an electronic device provided in an embodiment of the present application is shown;

[0053] Figure 7 A diagram showing a computer-readable storage medium provided in an embodiment of the present application.

[0054] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0055] 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.

[0056] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0057] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0058] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0060] In the method provided in the embodiment of the present application, a specific current waveform (high-frequency square wave voltage and low-frequency square wave current) is injected into the D axis (direct axis) of the motor, the rotor position is estimated by the position observer, and the magnetic saturation characteristics of the motor are used to identify the polarity of the rotor (N pole or S pole). The time for rotor position detection can be reduced and the detection accuracy can be improved.

[0061] The D-axis demand current is given in the form of a trapezoidal wave, rather than a traditional low-frequency square wave signal. This waveform is designed to enhance the motor inductance saturation effect while reducing the risk of overcurrent caused by sudden changes in demand current, thereby improving identification accuracy and safety. After the D-axis demand current reaches the preset value, a waiting time is added to ensure that the current is stable. Afterwards, the D-axis high-frequency current response is accumulated and averaged to improve the credibility of the data and reduce the problem of polarity misjudgment caused by current fluctuations or sampling errors.

[0062] Figure 1 A method for identifying an initial position of a motor rotor provided in an embodiment of the present application is shown, the method comprising:

[0063] Step 101: injecting a pulse voltage signal into the stator of the motor so that the stator current generates a stator magnetic field and the rotor permanent magnet generates a rotor magnetic field;

[0064] Step 102: Calculate the current response variation factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time by controlling the direction and magnitude of the stator current;

[0065] Step 103: Identify the initial position of the motor rotor according to the current response variation factors in the different relative directions.

[0066] The purpose of the technical solution of the embodiment of the present application is to develop a method for identifying the initial position of the motor rotor, which uses the interaction between the stator magnetic field and the rotor magnetic field to determine the initial position of the rotor. By injecting a pulse voltage signal into the motor stator and controlling the direction and magnitude of the stator current, the method can measure the current response change factor in different relative directions, thereby identifying the initial position of the rotor. This method aims to improve the accuracy and efficiency of motor control, especially in the motor startup and fault diagnosis stages.

[0067] In a possible implementation manner, when the stator magnetic field and the rotor magnetic field have the same direction, in step 102, calculating the current response change factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time by controlling the direction and magnitude of the stator current includes:

[0068] The stator current is gradually increased to a set current positive value according to a set gradient and maintained for a set stable time, and then the stator current is gradually reduced to 0 according to a set gradient, and then the stator current is reversely increased to a set current negative value according to the set gradient and maintained for a set stable time; the current response change factor of the stator current within the predetermined time is calculated. Regardless of whether the stator magnetic field is in the opposite direction to the rotor magnetic field, a positive stator current needs to be injected first, and then a negative stator current needs to be injected, and then the high-frequency current response amplitudes corresponding to the two injected currents are compared.

[0069] In a possible implementation manner, when the stator magnetic field and the rotor magnetic field are in opposite directions, in step 102, calculating the current response change factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time by controlling the direction and magnitude of the stator current includes:

[0070] The stator current is gradually reduced to 0 according to the set gradient, and then continued to be increased to a set current positive value according to the set gradient and maintained for a set stable time; and the current response change factor of the stator current within the predetermined time is calculated.

[0071] Suppose there is a servo motor of an industrial robot, and the initial position of its arm needs to be precisely controlled in order to perform precise operations. Before the motor starts, a pulse voltage signal is injected into the motor stator using the above method to generate a stator magnetic field. At the same time, the rotor permanent magnet generates a rotor magnetic field. By controlling the direction and magnitude of the stator current, the interaction between the stator magnetic field and the rotor magnetic field in the same and opposite directions is simulated, and the current response change factors are calculated. These factors reflect the strength and characteristics of the interaction between the two magnetic fields. By comparing these factors, the initial position of the rotor can be determined, thereby ensuring that the motor can start from the correct position and achieve precise control. This method not only improves the accuracy of robot operation, but also reduces the risk of failure caused by position error and enhances the stability and reliability of the system.

[0072] In a possible implementation manner, in step 102, calculating the current response change factor of the stator current within the predetermined time includes:

[0073] The direct-axis high-frequency response current of each sampling point within the predetermined time is measured; the cumulative value of the direct-axis high-frequency response current of all sampling points at each measuring moment is calculated; and the current response average value is obtained according to the cumulative value of the direct-axis high-frequency response current of all sampling points and the number of the sampling points as the current response variation factor.

[0074] The initial position of the rotor is determined by measuring and calculating the direct-axis high-frequency response current of the stator current in detail. This method obtains the current response change factor by measuring, accumulating, and calculating the average value of the direct-axis high-frequency response current of each sampling point within a predetermined time, thereby identifying the rotor position. Assume that in a traction motor of an electric vehicle, it is necessary to determine the initial position of the rotor before starting to optimize the starting process. Using the above method, the direct-axis high-frequency response current of each sampling point within a predetermined time is measured in step 102, and then these current values ​​are accumulated and the average value is calculated as the current response change factor. If the stator magnetic field and the rotor magnetic field are in the same direction, a larger current response change factor is expected; if the directions are opposite, a smaller current response change factor is expected. By comparing these factors, the initial position of the rotor can be determined, thereby optimizing the starting strategy of the motor, reducing energy consumption and wear during starting, and improving the performance and reliability of the vehicle.

[0075] In a possible implementation manner, in step 103, identifying the initial position of the motor rotor according to the current response variation factor in the different relative directions includes:

[0076] The absolute value of the current response change factor when the stator magnetic field and the rotor magnetic field are in the same direction is determined as the first current factor; the absolute value of the current response change factor when the stator magnetic field and the rotor magnetic field are in opposite directions is determined as the second current factor; if the first current factor is greater than the second current factor, the initial position of the motor rotor is the N pole; if the first current factor is less than the second current factor, the initial position of the motor rotor is the S pole.

[0077] The initial position of the motor rotor is identified by comparing the current response change factors under different relative directions. By determining the current response change factors when the stator magnetic field is in the same and opposite directions as the rotor magnetic field and comparing their sizes, it is possible to accurately determine whether the initial position of the rotor is the N pole or the S pole. Assume that the absolute value of the current response change factor is measured and calculated when the stator magnetic field and the rotor magnetic field are in the same direction, and it is determined as the first current factor. Then, when the stator magnetic field and the rotor magnetic field are in opposite directions, the absolute value of the current response change factor is measured and calculated, and it is determined as the second current factor. The initial position of the rotor can be determined by comparing the sizes of these two factors. If the first current factor is greater than the second current factor, the initial position of the rotor is the N pole; if the first current factor is less than the second current factor, the initial position of the rotor is the S pole.

[0078] In a possible implementation, the method further includes: controlling the direction and magnitude of the stator current so that the stator magnetic field has the same direction as the rotor magnetic field; specifically including: converting the stator current from a three-phase coordinate system to a two-phase rotating coordinate system, wherein the stator magnetic field is aligned with the rotor magnetic field; wherein the stator current is decomposed into a d-axis component and a q-axis component which are parallel and perpendicular to the rotor magnetic field, respectively; calculating the d-axis current component and the q-axis current component according to the requirements of motor control, and generating corresponding control signals; converting the voltage component in the two-phase rotating coordinate system back to the three-phase coordinate system to obtain the three-phase voltage component; generating a pulse width modulation signal according to the three-phase voltage component to control the motor phase current; monitoring the actual phase current of the motor in real time, and aligning the d-axis current component with the rotor magnetic field by adjusting the pulse width modulation signal, and the q-axis current component is used to control the torque of the motor.

[0079] In a possible implementation, the method further includes: controlling the direction and magnitude of the stator current so that the stator magnetic field is opposite to the direction of the rotor magnetic field; specifically including: converting the stator current from a three-phase coordinate system to a two-phase rotating coordinate system, wherein the stator magnetic field is aligned with the rotor magnetic field; wherein the stator current is decomposed into a d-axis component and a q-axis component which are parallel and perpendicular to the rotor magnetic field, respectively; calculating the d-axis current component and the q-axis current component according to the requirements of motor control; wherein the d-axis current component is adjusted so that the stator magnetic field is opposite to the rotor magnetic field; generating a corresponding control signal according to the calculated d-axis current component and the q-axis current component; wherein the d-axis control signal is adjusted to be opposite to the direction of the rotor magnetic field; converting the voltage component in the two-phase rotating coordinate system back to the three-phase coordinate system to obtain a three-phase voltage component; generating a pulse width modulation signal according to the three-phase voltage component to control the motor phase current; monitoring the actual phase current of the motor in real time, and adjusting the pulse width modulation signal so that the d-axis current component is opposite to the rotor magnetic field.

[0080] The relative direction of the stator magnetic field and the rotor magnetic field is adjusted by controlling the direction and magnitude of the stator current, thereby identifying the initial position of the rotor. This method includes two implementations: one is to control the stator current so that the stator magnetic field and the rotor magnetic field are in the same direction, and the other is to control the stator current so that the stator magnetic field and the rotor magnetic field are in opposite directions. Through these two methods, the current response change factor can be accurately measured and the position of the rotor can be determined accordingly.

[0081] The motor rotor initial position identification method provided in the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0082] In the embodiment of the present application, the nonlinear saturation characteristics of the stator core of the permanent magnet synchronous motor are utilized, and the pulse voltage signal injection method is used to determine the rotor polarity. The principle of polarity judgment is to inject a constant voltage into the stator D axis, the stator current generates a magnetic field ψs, and the rotor permanent magnet generates ψf. When the two magnetic fields are in the same direction, the magnetic field synthesized by the air gap will be assisted, which will increase the magnetic saturation degree of the stator core, increase the stator magnetic resistance, and then reduce the inductance of the winding. The winding current is inversely proportional to the inductance, so the winding current will increase; on the contrary, if the two magnetic fields are in opposite directions, a demagnetization effect will be generated, which will weaken the saturation degree of the stator core, reduce the magnetic resistance, increase the inductance, and reduce the winding current.

[0083] Figure 2a , Figure 2b , Figure 2c , Figure 2d The effects of two different magnetic field directions on the magnetic saturation degree of the stator core are demonstrated. Figure 2a and Figure 2bThe figure shows the cases where the magnetic field directions are the same (magnetization) and opposite (demagnetization). In the case of magnetization, the stator magnetic resistance increases, the inductance decreases, and the current increases; while in the case of demagnetization, the magnetic resistance decreases, the inductance increases, and the current decreases.

[0084] Figure 2c and Figure 2d The relationship between inductance L and flux linkage ψ is shown when injecting current in different directions to identify the rotor polarity in a permanent magnet synchronous motor (PMSM). These two figures are a quantitative description of the magnetic saturation effect in this method. Figure 2c In the diagram, the horizontal axis (B) represents the flux linkage ψ, which is a measure of the magnetic flux in the motor. The vertical axis (H) represents the magnetic field strength, which is proportional to the current. f Represents the flux linkage of the permanent magnet. f +λ inj (+U L ) means that when the direction of the injected current is the same as the direction of the permanent magnet magnetic field (magnetic assistance), the total magnetic flux increases, the inductance L decreases, and the current increases. f -λ inj (-U L ) indicates that when the direction of the injected current is opposite to the direction of the permanent magnet magnetic field (demagnetization), the total flux decreases, the inductance L increases, and the current decreases. Figure 2c In the figure, we can see that the two solid lines represent the inductance changes in the magnetizing and demagnetizing conditions respectively. The dotted line represents the inductance change when no current is injected. Figure 2d and Figure 2c Similarly, under different current injection strategies or different motor parameters. Figure 2d In the figure, the solid and dotted lines also represent the change in inductance under different current injection conditions. By comparing these curves, the effect of current injection on inductance can be observed, which can be used to identify the polarity of the rotor. The effect of current injection on the magnetic saturation effect of the motor is intuitively demonstrated by showing the relationship between inductance L and flux ψ. This effect can be used to distinguish the polarity of the rotor, because different polarities will result in different degrees of magnetic saturation and inductance changes. This method takes advantage of the physical characteristics of the motor and achieves fast and accurate identification of the initial position of the rotor by precisely controlling the current injection.

[0085] Based on the original high-frequency square wave injection, the fundamental wave demand current in the estimated D-axis direction is set to increase slowly from 0 to a given I Dreq , the fundamental wave demand current of the D axis is always 0. After the demand current reaches the given value, wait for a period of time t1 to make the current stable, then accumulate the high-frequency current response of the D axis in the time period t2, and calculate the average value of the high-frequency current response of the D axis in the current working condition in the time period t2, recorded as I DHi1 .

[0086] If the injected current is in the direction of the rotor N pole, the magnetic field generated by the stator current is in the same direction as the magnetic field generated by the rotor permanent magnet, which plays a magnetic assisting role, making the magnetic resistance larger, the inductance Ld smaller, and the D-axis high-frequency current response larger. Then the D-axis demand current is continuously reduced to 0 according to the same gradient, and increased in the opposite direction to the given -I Dreq When the demand current reaches the given value, wait for a period of time t1 to stabilize the current, accumulate the D-axis high-frequency current response in the t2 period, and calculate the average value of the D-axis high-frequency current response of the current working condition in the t2 period, which is recorded as I DHi2 .

[0087] If the injected current is in the direction of the rotor S pole, the magnetic field generated by the stator current is opposite to the magnetic field generated by the rotor permanent magnet, which plays a demagnetizing role, making the magnetic resistance smaller, the inductance Ld larger, and the D-axis high-frequency current response smaller. DHi1 with I DHi2 , if |I DHi1 |>|I DHi2 |, then it can be determined that the rotor position is N pole, that is, the identified angle is the actual angle. Conversely, the rotor position is S pole, that is, the identified angle differs from the actual angle by 180 degrees.

[0088] By giving the D-axis demand current in the form of a trapezoidal wave, the motor is magnetized and demagnetized to enhance the motor inductance saturation effect. At the same time, after the D-axis demand current reaches the preset current, wait for a period of time for the current to stabilize, and then accumulate and calculate the average value of the D-axis high-frequency current response. By comparing the D-axis high-frequency current response (I DHi1 with I DHi2 ), determine the polarity of the rotor. If |I DHi1 |>|I DHi2 |, the rotor position is N pole; otherwise, it is S pole. This improves the credibility of the data, reduces the problem of polarity misjudgment caused by current fluctuations or sampling errors, and improves the accuracy of polarity discrimination.

[0089] Figure 3 The system logic flow chart of polarity judgment is shown, and the control process of the permanent magnet synchronous motor (PMSM) rotor initial position identification method is described. The system regulates the current through the current loop PI controller and uses the inverse Park transform and SVPWM (space vector pulse width modulation) to control the IPMS (internal permanent magnet synchronous motor). The three-phase current (Ia, Ib, Ic) of the motor can be monitored through Park transform and Clark transform. If the D-axis current (I d ) is less than 0, the system will adjust the angle θ to ensure the correct current direction.

[0090] At the beginning of the system, the rotor position of the permanent magnet synchronous motor (PMSM) is unknown.

[0091] Phase 1: The current loop PI controller regulates the motor's D-axis (direct axis) and q-axis (quadrature axis) currents.

[0092] In the figure, it receives the target current value (Id and Iq) and outputs control signals (ud and uq) to adjust the current of the motor. Id is the D-axis current and Iq is the q-axis current. In the control of PMSM, the current loop PI controller sets the target current Id to 0 and Iq to 0 to achieve field-oriented control.

[0093] A pulse voltage signal is injected into the stator D axis to generate a magnetic field ψs. The PI controller calculates the required current value based on the magnetic field ψs that needs to be generated, and outputs a control signal (ud,uq) to adjust the motor current. The control signal output by the current loop PI controller can be used to determine the direction of the current after the inverse Park transformation, thereby inferring the relationship between the magnetic field ψs and the magnetic field ψf generated by the rotor permanent magnet.

[0094] The second stage: The inverse Park transform converts the current components in the dq coordinate system into the current components in the three-phase stationary coordinate system.

[0095] Phase III: Space Vector Pulse Width Modulation SVPWM is a PWM technique used to control PMSM. It generates PWM signals based on the current components after inverse Park transformation to control the phase current of the motor.

[0096] Stage 4: The internal permanent magnet synchronous motor IPMSM is the controlled motor model, which receives the PWM signal generated by SVPWM and generates three-phase current (Ia, Ib, Ic).

[0097] The fifth stage: Clark transformation converts the three-phase current (Ia, Ib, Ic) into the current component (I DHi1 and I DHi2 ). This is a prerequisite for the Park transform, because the Park transform requires the current in the two-phase stationary coordinate system as input.

[0098] Clark transformation converts the three-phase current (Ia, Ib, Ic) into current components in a two-phase stationary coordinate system, which can then be used to calculate the high-frequency current response of the D axis. Dreq After that, the system will wait for time t1 to stabilize the current, and then accumulate the D-axis high-frequency current response during the t2 period and calculate the average value I DHi1 .

[0099] Stage 6: Park transformation converts the current components in the two-phase stationary coordinate system (α-β coordinate system) into current components (Id, Iq) in the rotating coordinate system (dq coordinate system).

[0100] The Park-transformed dq coordinate system current components (Id, Iq) are fed into the current loop PI controller. The controller adjusts the control signal to regulate the motor current based on the difference between the set target current value (usually Id is 0 and Iq is also 0 at startup) and the actual current value. After the current loop PI controller outputs the control signal, the inverse Park transform converts the control signal in the dq coordinate system back to the three-phase stationary coordinate system to generate a PWM signal suitable for motor drive. Finally, the SVPWM module generates a PWM signal based on the inverse Park-transformed signal to control the phase current of the motor. The polarity of the rotor can be determined by injecting current into the stator D axis and monitoring the high-frequency current response of the D axis. Park transform is used in this process to convert the three-phase current into current components in the dq coordinate system so that the current can be controlled and monitored more accurately.

[0101] The controller will adjust the output signal so that the D-axis demand current decreases to 0 and increases in the reverse direction to -I Dreq The system waits for time t1 again to stabilize the current, and then accumulates the D-axis high-frequency current response during the t2 period and calculates the average value I DHi2 .

[0102] Stage 7: Make the difference module by comparing I DHi1 and I DHi2 The absolute value of |I DHi1 |>|I DHi2 |, the rotor position is N-pole; otherwise, it is S-pole. This allows the system to determine the polarity of the rotor and thus correctly identify the initial position of the rotor.

[0103] Stage 8: If Id<0, that is, the D-axis current is negative, the system will adjust the angle θ to ensure the correct current direction.

[0104] The above control process achieves fast and accurate identification of the initial position of the rotor by precisely controlling the motor current and utilizing the magnetic saturation characteristics of the PMSM. Through the current loop PI controller and SVPWM, the system can dynamically adjust the motor current in response to changes in the rotor position. Clark transform and Park transform are used to monitor the current and calculate the position of the rotor. The entire system is designed to improve the accuracy of rotor position detection and the robustness of the system.

[0105] The current loop PI controller adjusts the motor current according to the trapezoidal wave current requirements, and the inverse Park transformation and SVPWM modules generate corresponding control signals based on these adjustments. Figure 4 The schematic diagram of the trapezoidal wave current is shown. The trapezoidal wave current is a non-sinusoidal waveform that reaches the maximum value and maintains it for a period of time before gradually decreasing back to zero. This waveform can reduce the sudden change of current, thereby reducing the risk of current fluctuation and overcurrent. Figure 4 In the process, the current gradually increases from 0 to a preset maximum value (I Dreq ), this process is linear and can reduce the sudden change of current. The current is kept at the maximum value for a period of time (t1). This waiting time allows the current to stabilize and reduce the impact of current fluctuations on the measurement. Then, the current gradually decreases back to 0. This process is also linear. After the current stabilizes, the system will collect data on the high-frequency current response of the D axis for a period of time (t2). The collected data will be accumulated and the average value will be calculated. This average value (I DHi1 ) is used for subsequent polarity judgment.

[0106] In this method, the D-axis demand current is set to a trapezoidal wave instead of a rectangular wave to avoid current mutations, improve dynamic following effects, and reduce current fluctuations and overcurrent risks. Compared with rectangular waves, trapezoidal waves can provide smoother current changes and reduce the impact of current mutations. Through the trapezoidal wave, the magnetic saturation effect of the motor can be better controlled, thereby improving the accuracy of polarity discrimination. By giving the D-axis demand current as a trapezoidal wave, the motor inductance saturation effect can be enhanced and the accuracy of polarity discrimination can be improved. After the current stabilizes, by waiting for a period of time (t1) and calculating the average value of the D-axis high-frequency current response in the t2 time period, the credibility of the data can be improved and the misjudgment caused by current fluctuations or sampling errors can be reduced. The advantages of this method include reducing the rotor position detection time, improving detection accuracy, suppressing interference, and enhancing the robustness of the system. Through these technical means, the accuracy and reliability of the initial position identification of the permanent magnet synchronous motor rotor can be effectively improved.

[0107] In summary, the embodiment of the present application provides a method for identifying the initial position of a motor rotor, by injecting a pulse voltage signal into the stator of the motor so that the stator current generates a stator magnetic field, and the rotor permanent magnet generates a rotor magnetic field; by controlling the direction and magnitude of the stator current, the current response change factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time is calculated; and the initial position of the motor rotor is identified according to the current response change factor in different relative directions. By injecting a pulse voltage signal into the stator of the motor, the direction and magnitude of the stator current are precisely controlled so as to measure the interaction between the stator magnetic field and the rotor magnetic field in different relative directions. This interaction is characterized by the current response change factor, thereby realizing accurate identification of the initial position of the motor rotor.

[0108] Based on the same technical concept, the present application also provides a motor rotor initial position identification system. Figure 5 As shown, the system comprises:

[0109] A magnetic field generating module 501 is used to inject a pulse voltage signal into the stator of the motor so that the stator current generates a stator magnetic field and the rotor permanent magnet generates a rotor magnetic field;

[0110] A current response calculation module 502, configured to calculate a current response variation factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time by controlling the direction and magnitude of the stator current;

[0111] The position identification module 503 is used to identify the initial position of the motor rotor according to the current response change factor in the different relative directions.

[0112] The present application also provides an electronic device corresponding to the method provided in the above embodiment. Figure 6 , which shows an electronic device diagram provided by some embodiments of the present application. The electronic device 20 may include: a processor 200, a memory 201, a bus 202 and a communication interface 203, wherein the processor 200, the communication interface 203 and the memory 201 are connected via the bus 202; the memory 201 stores a computer program that can be run on the processor 200, and the processor 200 executes the method provided by any of the aforementioned embodiments of the present application when running the computer program.

[0113] The memory 201 may include a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory. The communication connection between the system network element and at least one other network element is realized through at least one physical port (which may be wired or wireless), and the Internet, wide area network, local area network, metropolitan area network, etc. may be used.

[0114] The bus 202 may be an ISA bus, a PCI bus, or an EISA bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. The memory 201 is used to store programs, and the processor 200 executes the programs after receiving execution instructions. The method disclosed in any implementation of the aforementioned embodiment of the present application may be applied to the processor 200, or implemented by the processor 200.

[0115] The processor 200 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit or software instructions in the processor 200. The above processor 200 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a readily available programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application can be directly embodied as a hardware decoding processor to be executed, or the hardware and software modules in the decoding processor can be executed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 201, and the processor 200 reads the information in the memory 201 and completes the steps of the above method in combination with its hardware.

[0116] The electronic device provided in the embodiment of the present application and the method provided in the embodiment of the present application are based on the same inventive concept and have the same beneficial effects as the method adopted, operated or implemented by them.

[0117] The present application also provides a computer-readable storage medium corresponding to the method provided in the above embodiment. Figure 7 The computer-readable storage medium shown is a CD 30 on which a computer program (ie, a program product) is stored. When the computer program is run by a processor, the method provided in any of the aforementioned embodiments is executed.

[0118] It should be noted that examples of the computer-readable storage medium may also include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other optical or magnetic storage media, which are not listed here one by one.

[0119] The computer-readable storage medium provided in the above-mentioned embodiments of the present application and the method provided in the embodiments of the present application are based on the same inventive concept and have the same beneficial effects as the method adopted, run or implemented by the application program stored therein.

[0120] It should be noted that the above embodiments illustrate the present application rather than limit the present application, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be constructed as a limitation to the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of multiple such elements. The present application may be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In a unit claim that lists several devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

[0121] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

[0122] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for identifying the initial position of a motor rotor, characterized in that: The method comprises: A pulse voltage signal is injected into the stator of the motor so that the stator current generates a stator magnetic field, and the rotor permanent magnet generates a rotor magnetic field; By controlling the direction and magnitude of the stator current, a current response variation factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time is calculated; The initial position of the motor rotor is identified according to the current response variation factors in the different relative directions.

2. The method according to claim 1, characterized in that When the stator magnetic field and the rotor magnetic field have the same direction, the current response change factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time is calculated by controlling the direction and magnitude of the stator current, including: The stator current is gradually reduced to 0 according to the set gradient, and then increased in the reverse direction according to the set gradient to the set current negative value and maintained for the set stable time; A current response variation factor of the stator current within the predetermined time is calculated.

3. The method according to claim 1, characterized in that When the stator magnetic field is in opposite directions to the rotor magnetic field, the current response change factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time is calculated by controlling the direction and magnitude of the stator current, including: The stator current is gradually reduced to 0 according to the set gradient, and then continued to increase to the set current positive value according to the set gradient and maintained for the set stable time; A current response variation factor of the stator current within the predetermined time is calculated.

4. The method according to any one of claims 1 to 3, characterized in that: The calculating the current response change factor of the stator current within the predetermined time includes: Measuring the direct-axis high-frequency response current of each sampling point within the predetermined time; Calculate the cumulative value of the direct-axis high-frequency response current of all sampling points at each measurement moment; The current response average value is obtained according to the direct-axis high-frequency response current cumulative value of all sampling points and the number of the sampling points, which is used as the current response variation factor.

5. The method according to claim 4, characterized in that Identifying the initial position of the motor rotor according to the current response change factors in the different relative directions includes: Determine the absolute value of the current response change factor when the stator magnetic field and the rotor magnetic field have the same direction as the first current factor; Determine the absolute value of the current response change factor when the stator magnetic field and the rotor magnetic field are in opposite directions as a second current factor; If the first current factor is greater than the second current factor, the initial position of the motor rotor is the N pole; If the first current factor is smaller than the second current factor, the initial position of the motor rotor is the S pole.

6. The method according to claim 1, characterized in that The method further includes: controlling the direction and magnitude of the stator current so that the stator magnetic field has the same direction as the rotor magnetic field; specifically including: Converting the stator current from a three-phase coordinate system to a two-phase rotating coordinate system, wherein the stator magnetic field is aligned with the rotor magnetic field; wherein the stator current is decomposed into a d-axis component and a q-axis component that are parallel and perpendicular to the rotor magnetic field, respectively; Calculate the d-axis current component and the q-axis current component according to the motor control requirements and generate corresponding control signals; The voltage components in the two-phase rotating coordinate system are converted back to the three-phase coordinate system to obtain the three-phase voltage components; Generate pulse width modulation signals according to three-phase voltage components to control motor phase currents; The actual phase current of the motor is monitored in real time, and the d-axis current component is aligned with the rotor magnetic field by adjusting the pulse width modulation signal. The q-axis current component is used to control the torque of the motor.

7. The method according to claim 1, characterized in that The method further includes: controlling the direction and magnitude of the stator current so that the stator magnetic field is opposite to the rotor magnetic field; specifically including: Converting the stator current from a three-phase coordinate system to a two-phase rotating coordinate system, wherein the stator magnetic field is aligned with the rotor magnetic field; wherein the stator current is decomposed into a d-axis component and a q-axis component that are parallel and perpendicular to the rotor magnetic field, respectively; The d-axis current component and the q-axis current component are calculated according to the requirements of the motor control; wherein the d-axis current component is adjusted so that the stator magnetic field and the rotor magnetic field are in opposite directions; Generate a corresponding control signal according to the calculated d-axis current component and q-axis current component; wherein the d-axis control signal is adjusted to be opposite to the direction of the rotor magnetic field; The voltage components in the two-phase rotating coordinate system are converted back to the three-phase coordinate system to obtain the three-phase voltage components; Generate pulse width modulation signals according to three-phase voltage components to control motor phase currents; The actual phase current of the motor is monitored in real time, and the pulse width modulation signal is adjusted so that the d-axis current component is opposite to the rotor magnetic field.

8. A motor rotor initial position identification system, characterized in that: The system comprises: A magnetic field generating module is used to inject a pulse voltage signal into the stator of the motor so that the stator current generates a stator magnetic field, and the rotor permanent magnet generates a rotor magnetic field; A current response calculation module, used to calculate a current response variation factor of the stator magnetic field and the rotor magnetic field in different relative directions within a predetermined time by controlling the direction and magnitude of the stator current; The position identification module is used to identify the initial position of the motor rotor according to the current response change factor in the different relative directions.

9. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: Computer-readable instructions are stored thereon, and the computer-readable instructions can be executed by a processor to implement the method according to any one of claims 1-7.

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