CN107294458B - Permanent magnet synchronous motor stator flux linkage observation method, flux linkage observer and storage medium - Google Patents
Permanent magnet synchronous motor stator flux linkage observation method, flux linkage observer and storage medium Download PDFInfo
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- H—ELECTRICITY
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- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/24—Vector control not involving the use of rotor position or rotor speed sensors
- H02P21/28—Stator flux based control
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/13—Observer control, e.g. using Luenberger observers or Kalman filters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
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Abstract
The invention discloses a permanent magnet synchronous motor stator flux linkage observation method, a flux linkage observer and a storage medium. According to the invention, the linear region of the mapping curve is searched, resistance identification is carried out on the basis of the linear region of the mapping curve, the stator resistance of the permanent magnet synchronous motor is obtained, the current value of the motor is obtained, the corresponding current delay time difference is determined by adopting the mapping curve according to the current value, the command voltage is corrected according to the current delay time difference, and the stator flux linkage of the permanent magnet synchronous motor is calculated according to the stator resistance and the corrected command voltage, so that the adopted stator resistance and the command voltage are more accurate, and the stator flux linkage is more accurate.
Description
Technical Field
The invention relates to the technical field of flux linkage observation, in particular to a permanent magnet synchronous motor stator flux linkage observation method, a flux linkage observer and a storage medium.
Background
The permanent magnet synchronous motor has the advantages of high efficiency, high power density, small torque pulsation, wide speed regulation range and the like, and is widely applied to the fields of household appliances, electric automobiles, high-speed rails, aerospace and the like at present.
The common permanent magnet synchronous motor variable frequency speed control system usually performs speed closed-loop control according to a speed given signal and a speed feedback signal, so that a speed sensor is required to acquire speed information. However, the installation of the speed sensor not only increases the cost, but also the speed sensor is easy to malfunction and fail under certain severe working conditions, so that the reliability of the motor speed regulating system is reduced. For the above reasons, in recent years, a speed sensorless control method, which can estimate speed information from a motor mathematical model alone without installing a speed sensor, has become a hot spot of academic research. Specifically, the angle of the rotor flux linkage is first calculated from the stator flux linkage, and then the position information and the speed information of the rotor are further calculated. Therefore, the accuracy of stator flux linkage observation directly determines the accuracy of the position and speed information of the motor rotor, and finally influences the accuracy of motor control.
The conventional permanent magnet synchronous motor stator flux linkage observation methods comprise a method for calculating a stator flux linkage based on a mathematical model under a two-phase synchronous rotating coordinate system (called a d-q coordinate system for short) according to an actually measured current and a rotor position angle, a method for calculating a stator flux linkage based on a mathematical model under a two-phase static coordinate system (called a α - β coordinate system for short) according to the actually measured voltage and current, and a method for calculating a stator flux linkage based on a voltage model.
The voltage model has three input quantities, namely phase voltage, phase current and stator resistance, and only if the three input quantities are accurate, the output stator flux linkage is accurate. In practical applications, the phase currents of the motor are usually easily detected, while the phase voltages and the stator resistance are usually difficult to detect. Since adding a phase voltage detection circuit increases cost and decreases reliability, the phase voltage is not usually detected in engineering, but the command value using the phase voltage is approximately equivalent. The resistance of the stator changes along with the temperature change in the operation process of the motor, and generally needs real-time online identification or periodic offline identification.
However, in practical applications, the output voltage of the inverter may be affected by the non-linearity of the switch, and thus has a certain deviation. Because the prior art does not consider the influence of nonlinear factors of the switch, the command value and the actual value of the phase voltage have deviation, and the resistance identification result also has deviation. Therefore, the prior art does not calculate the stator flux linkage accurately.
The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.
Disclosure of Invention
The invention mainly aims to provide a permanent magnet synchronous motor stator flux linkage observation method, a flux linkage observer and a storage medium, and aims to solve the technical problem that stator flux linkage is inaccurate in the prior art.
In order to achieve the above object, the present invention provides a method for observing flux linkage of a stator of a permanent magnet synchronous motor, the method comprising the steps of:
searching a linear region of a mapping curve, wherein the mapping curve is a curve reflecting the corresponding relation between the delay time difference and the current value;
performing resistance identification based on the linear region of the mapping curve to obtain the stator resistance of the permanent magnet synchronous motor;
acquiring a current value of a motor, and determining a corresponding current delay time difference by adopting a mapping curve according to the current value;
correcting the command voltage according to the current delay time difference;
and calculating the stator flux linkage of the permanent magnet synchronous motor according to the stator resistance and the corrected command voltage.
Preferably, the correcting the command voltage according to the current delay time difference specifically includes:
calculating a terminal voltage error according to the current delay time difference;
carrying out coordinate transformation on the terminal voltage error to obtain a voltage compensation value under an α - β coordinate system;
and correcting the command voltage according to the voltage compensation value in the α - β coordinate system.
Preferably, the stator flux linkage of the permanent magnet synchronous motor is calculated by the following formula according to the stator resistance and the corrected command voltage,
wherein psiα_estAnd psiβ_estIs the stator flux linkage, V, of the PMSMαAnd VβFor corrected command voltage value, RsIs stator resistance, iαCurrent value of α axis, iβThe current value of the axis β.
Preferably, the obtaining a current value of the motor, and determining a corresponding current delay time difference by using a mapping curve according to the current value specifically includes:
and acquiring the current value of the motor, and determining the corresponding current delay time difference by adopting the linear region according to the current value.
Preferably, the determining the corresponding current delay time difference by using the linear region according to the current value specifically includes:
and selecting two reference points from the linear area, acquiring a reference current value and a reference delay time difference of each reference point, and determining the current delay time difference according to the current value, the reference current value and the reference delay time difference of each reference point.
Preferably, the identifying the resistance based on the linear region of the mapping curve to obtain the stator resistance of the permanent magnet synchronous motor specifically includes:
selecting a current value in the linear region;
taking the selected current value as a direct-axis current value injected into the permanent magnet synchronous motor, and detecting a direct-axis voltage value corresponding to the direct-axis current value;
and calculating the stator resistance of the permanent magnet synchronous motor according to the direct-axis current value and the corresponding direct-axis voltage value.
Preferably, the searching for the linear region of the mapping curve specifically includes:
and acquiring the tangent slope of each point on the mapping curve, and determining the linear region according to the tangent slope.
Preferably, the determining the linear region according to the tangent slope specifically includes:
taking a point where the slope of the tangent line is equal to a preset slope as a segmentation point;
dividing the mapping curve according to the dividing points to obtain at least two dividing areas;
and judging whether each partition area has a point with a tangent slope larger than a preset slope or not, and taking the partition area without the point with the tangent slope larger than the preset slope as the linear area.
Further, to achieve the above object, the present invention also provides a flux linkage observer including: the permanent magnet synchronous motor stator flux linkage observation program is stored on the memory and can run on the processor, and the permanent magnet synchronous motor stator flux linkage observation program is configured to realize the steps of the permanent magnet synchronous motor stator flux linkage observation method.
In addition, to achieve the above object, the present invention further provides a computer readable storage medium, in which a permanent magnet synchronous motor stator flux linkage observation program is stored, and the permanent magnet synchronous motor stator flux linkage observation program, when executed by a processor, implements the steps of the permanent magnet synchronous motor stator flux linkage observation method.
According to the invention, the linear region of the mapping curve is searched, resistance identification is carried out on the basis of the linear region of the mapping curve, the stator resistance of the permanent magnet synchronous motor is obtained, the current value of the motor is obtained, the corresponding current delay time difference is determined by adopting the mapping curve according to the current value, the command voltage is corrected according to the current delay time difference, and the stator flux linkage of the permanent magnet synchronous motor is calculated according to the stator resistance and the corrected command voltage, so that the adopted stator resistance and the command voltage are more accurate, and the stator flux linkage is more accurate.
Drawings
FIG. 1 is a schematic diagram of a flux linkage observer of a hardware operating environment according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a method for observing flux linkage of a permanent magnet synchronous motor according to a first embodiment of the present invention;
FIG. 3 is a waveform diagram of current and voltage during resistor identification according to an embodiment of the present invention;
FIG. 4 is a schematic flow chart of a stator flux linkage observation method of a permanent magnet synchronous motor according to a second embodiment of the present invention;
FIG. 5 is a schematic flow chart of a method for observing flux linkage of a permanent magnet synchronous motor according to a third embodiment of the present invention;
fig. 6 is a schematic diagram illustrating the variation of the delay time difference with the current and the temperature according to the embodiment of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a flux linkage observer of a hardware operating environment according to an embodiment of the present invention.
As shown in fig. 1, the flux linkage observer may include: a processor 1001, such as a CPU, a communication bus 1002, a user interface 1003, and a memory 1004. Wherein a communication bus 1002 is used to enable connective communication between these components. The user interface 1003 may include a Display screen (Display), an input unit such as a Keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface, a wireless interface. The memory 1004 may be a high-speed RAM memory or a non-volatile memory (e.g., a disk memory). The memory 1004 may alternatively be a storage device separate from the processor 1001.
Those skilled in the art will appreciate that the flux linkage observer structure shown in FIG. 1 does not constitute a limitation of the flux linkage observer and may include more or fewer components than shown, or some components in combination, or a different arrangement of components.
As shown in fig. 1, the memory 1004, which is a kind of computer storage medium, may include therein an operating system, a user interface module, and a permanent magnet synchronous motor stator flux linkage observation program.
In the flux linkage observer shown in fig. 1, the flux linkage observer calls a permanent magnet synchronous motor stator flux linkage observation program stored in the memory 1004 by the processor 1001, and performs the following operations:
searching a linear region of a mapping curve, wherein the mapping curve is a curve reflecting the corresponding relation between the delay time difference and the current value;
performing resistance identification based on the linear region of the mapping curve to obtain the stator resistance of the permanent magnet synchronous motor;
acquiring a current value of a motor, and determining a corresponding current delay time difference by adopting a mapping curve according to the current value;
correcting the command voltage according to the current delay time difference;
and calculating the stator flux linkage of the permanent magnet synchronous motor according to the stator resistance and the corrected command voltage.
Further, the processor 1001 may call the permanent magnet synchronous motor stator flux linkage observation program stored in the memory 1004, and further perform the following operations:
calculating a terminal voltage error according to the current delay time difference;
carrying out coordinate transformation on the terminal voltage error to obtain a voltage compensation value under an α - β coordinate system;
and correcting the command voltage according to the voltage compensation value in the α - β coordinate system.
Further, the processor 1001 may call the permanent magnet synchronous motor stator flux linkage observation program stored in the memory 1004, and further perform the following operations:
calculating the stator flux linkage of the permanent magnet synchronous motor according to the stator resistance and the corrected command voltage through the following formula,
wherein psiα_estAnd psiβ_estIs the stator flux linkage, V, of the PMSMαAnd VβFor corrected command voltage value, RsIs stator resistance, iαCurrent value of α axis, iβThe current value of the axis β.
Further, the processor 1001 may call the permanent magnet synchronous motor stator flux linkage observation program stored in the memory 1004, and further perform the following operations:
and acquiring the current value of the motor, and determining the corresponding current delay time difference by adopting the linear region according to the current value.
Further, the processor 1001 may call the permanent magnet synchronous motor stator flux linkage observation program stored in the memory 1004, and further perform the following operations:
and selecting two reference points from the linear area, acquiring a reference current value and a reference delay time difference of each reference point, and determining the current delay time difference according to the current value, the reference current value and the reference delay time difference of each reference point.
Further, the processor 1001 may call the permanent magnet synchronous motor stator flux linkage observation program stored in the memory 1004, and further perform the following operations:
selecting a current value in the linear region;
taking the selected current value as a direct-axis current value injected into the permanent magnet synchronous motor, and detecting a direct-axis voltage value corresponding to the direct-axis current value;
and calculating the stator resistance of the permanent magnet synchronous motor according to the direct-axis current value and the corresponding direct-axis voltage value.
Further, the processor 1001 may call the permanent magnet synchronous motor stator flux linkage observation program stored in the memory 1004, and further perform the following operations:
and acquiring the tangent slope of each point on the mapping curve, and determining the linear region according to the tangent slope.
Further, the processor 1001 may call the permanent magnet synchronous motor stator flux linkage observation program stored in the memory 1004, and further perform the following operations:
taking a point where the slope of the tangent line is equal to a preset slope as a segmentation point;
dividing the mapping curve according to the dividing points to obtain at least two dividing areas;
and judging whether each partition area has a point with a tangent slope larger than a preset slope or not, and taking the partition area without the point with the tangent slope larger than the preset slope as the linear area.
According to the scheme, the linear region of the mapping curve is searched, resistance identification is carried out on the basis of the linear region of the mapping curve, the stator resistance of the permanent magnet synchronous motor is obtained, the current value of the motor is obtained, the corresponding current delay time difference is determined by the mapping curve according to the current value, the command voltage is corrected according to the current delay time difference, the stator flux linkage of the permanent magnet synchronous motor is calculated according to the stator resistance and the corrected command voltage, the adopted stator resistance and the command voltage are more accurate, and therefore the stator flux linkage is more accurate.
Based on the hardware structure, the embodiment of the permanent magnet synchronous motor stator flux linkage observation method is provided.
Referring to fig. 2, fig. 2 is a schematic flow chart of a permanent magnet synchronous motor stator flux linkage observation method according to a first embodiment of the present invention.
In a first embodiment, the method for observing the flux linkage of the stator of the permanent magnet synchronous motor comprises the following steps:
s10: searching a linear region of a mapping curve, wherein the mapping curve is a curve reflecting the corresponding relation between the delay time difference and the current value;
in a specific implementation, a plurality of test tests may be performed to obtain a mapping curve, where the mapping curve is a curve reflecting a corresponding relationship between a delay time difference and a current value, but since a non-linear region with a relatively fast change range may exist in the mapping curve, if a selected current value is in the non-linear region, an identified resistance error is too large due to a too large delay time difference, and thus, a linear region with a relatively small change range in the mapping curve may be searched in this embodiment.
It should be noted that the delay time difference is a difference between the turn-off delay time and the turn-on delay time, and the calculation formula may adopt Δ tdelay＝tturn_off_delay-tturn_on_delayWherein, Δ tdelayFor a delay time difference, tturn_off_delayFor turn-off delay time, tturn_on_delayThe delay time is turned on.
It can be understood that, since the linear region generally has a slow variation amplitude, the slope of the tangent line thereof is generally small, and in order to facilitate searching for the linear region in the mapping curve, in the present embodiment, the slope of the tangent line of each point on the mapping curve can be obtained, and the linear region is determined according to the slope of the tangent line.
In order to realize fast search of the linear region, in this embodiment, a point where a slope of a tangent line is equal to a preset slope may be used as a dividing point; dividing the mapping curve according to the dividing points to obtain at least two dividing areas; and judging whether each partition area has a point with a tangent slope larger than a preset slope or not, and taking the partition area without the point with the tangent slope larger than the preset slope as the linear area.
It should be noted that, a large current value may exist in the linear region determined in step S10, and if an excessively large current value is selected, the permanent magnet synchronous motor may be damaged, or a component connected to the permanent magnet synchronous motor may be damaged, and in order to prevent this problem, in this embodiment, a preset current threshold may be set, and the region exceeding the preset current threshold in the linear region may be deleted.
It can be understood that, the preset current threshold may be set empirically or according to a plurality of tests, but considering that different permanent magnet synchronous motors may have different current-withstanding characteristics, in this embodiment, the preset current threshold may be set as the smaller of the maximum allowable current of the permanent magnet synchronous motor and the maximum allowable current of the frequency converter connected to the permanent magnet synchronous motor.
S20: performing resistance identification based on the linear region of the mapping curve to obtain the stator resistance of the permanent magnet synchronous motor;
in order to facilitate the resistance identification, in this embodiment, a current value may be selected in the linear region; taking the selected current value as a direct-axis current value injected into the permanent magnet synchronous motor, and detecting a direct-axis voltage value corresponding to the direct-axis current value; and calculating the stator resistance of the permanent magnet synchronous motor according to the direct-axis current value and the corresponding direct-axis voltage value.
It should be noted that since the linear region is usually small in variation, selecting the current value in the linear region can prevent the identified resistance error from being too large.
It is understood that the current value can be selected in the linear region by a random selection method, which is not limited in this embodiment.
It should be noted that, for a permanent magnet synchronous motor, a quadrature axis is also called a q axis, a direct axis is also called a d axis, the quadrature axis and the direct axis are coordinate axes in nature, and are not actual rotating shafts, in the control of the permanent magnet synchronous motor, in order to obtain control characteristics similar to a direct current motor, a coordinate system is established on a motor rotor, the coordinate system rotates synchronously with the rotor, the direction of a rotor magnetic field is taken as the d axis, and the direction perpendicular to the rotor magnetic field is taken as the q axis, and a mathematical model of the motor is converted into the coordinate system, so that decoupling of the d axis and the q axis can be realized, and good control characteristics can be obtained.
It can be understood that, in order to offset the effect of the delay time difference, two times of injecting current values are required, and therefore, in the present embodiment, two different current values are selected in the linear region, and in order to distinguish the selected current values, the selected current values can be divided into a first current value and a second current value.
Correspondingly, the detecting a direct-axis voltage value corresponding to the direct-axis current value by using the selected current value as the direct-axis current value injected into the permanent magnet synchronous motor may specifically include:
setting a preset angle as a given electrical angle (for convenience of subsequent calculation, in this embodiment, the preset angle may be 0 degree, and certainly, other angles may also be set, which is not limited in this embodiment), performing closed-loop control on a first direct current value by using a selected first current value as the first direct current value, obtaining a direct current voltage value when a feedback direct current value of the closed-loop control is consistent with the first direct current value, and using the obtained direct current voltage value as a first direct current voltage value corresponding to the first direct current value;
setting a preset angle as a given electrical angle, taking a selected second current value as a second straight-axis current value, performing closed-loop control on the second straight-axis current value, acquiring a direct-current voltage value when a feedback straight-axis current value of the closed-loop control is consistent with the second straight-axis current value, and taking the acquired direct-current voltage value as a second straight-axis voltage value corresponding to the second straight-axis current value.
It can be understood that, because the closed-loop control is usually implemented by a feedback comparison method, it usually requires a certain time to make the set value (i.e. the first direct current value or the second direct current value) and the feedback value (i.e. the feedback direct current value) consistent, but if the set value and the feedback value are not consistent yet, i.e. the dc voltage value is collected, the identified resistance error is too large, and therefore, in this embodiment, the dc voltage value is obtained only when the set value and the feedback value are consistent.
In a specific implementation, in order to improve the calculation efficiency, in this embodiment, the stator resistance of the permanent magnet synchronous motor may be calculated according to the direct-axis current value and the corresponding direct-axis voltage value by the following formula,
wherein R issIs the stator resistance, V, of the PMSMd1Is a first direct-axis voltage value, Vd2Is the second direct axis voltage value, id1Is a first direct current value, id2The second direct current value.
Specifically, during resistance identification, the waveform of current and voltage can be shownRefer to FIG. 3, wherein i1The corresponding point can be understood as the above-mentioned division point, imaxIs the above-mentioned predetermined current threshold.
S30: acquiring a current value of a motor, and determining a corresponding current delay time difference by adopting a mapping curve according to the current value;
it should be noted that the current value is a current value flowing through a switching tube on a bridge arm of a motor frequency converter at the current moment.
It will be appreciated that the present current value may be obtained in a number of ways, for example: the current value may be obtained by using a current sensor, or may be obtained by using a current detection chip, which is not limited in this embodiment.
In order to determine the current delay time difference, a plurality of test tests may be performed to obtain a mapping curve, where the mapping curve reflects a corresponding relationship between the delay time difference and the current value, and therefore, in this embodiment, step S30 may determine the corresponding current delay time difference according to the current value by using the mapping curve.
S40: correcting the command voltage according to the current delay time difference;
s50: and calculating the stator flux linkage of the permanent magnet synchronous motor according to the stator resistance and the corrected command voltage.
In the embodiment, a linear region of a mapping curve is searched, resistance identification is performed based on the linear region of the mapping curve, the stator resistance of the permanent magnet synchronous motor is obtained, the current value of the motor is obtained, the corresponding current delay time difference is determined by using the mapping curve according to the current value, the command voltage is corrected according to the current delay time difference, and the stator flux linkage of the permanent magnet synchronous motor is calculated according to the stator resistance and the corrected command voltage, so that the adopted stator resistance and the command voltage are more accurate, and the stator flux linkage is more accurate.
Further, as shown in fig. 4, a second embodiment of the method for observing the stator flux linkage of the permanent magnet synchronous motor according to the present invention is proposed based on the first embodiment.
In this embodiment, step S40 specifically includes:
s41: calculating a terminal voltage error according to the current delay time difference;
it can be understood that, because the motor in this embodiment is a three-phase variable frequency motor, and each phase of a frequency converter of the three-phase variable frequency motor has a bridge arm, and each bridge arm has an upper switching tube and a lower switching tube, respectively, the bridge arms on each phase have current values, and the current values of each phase are independent from each other and do not interfere with each other, so that the current values of each phase can calculate corresponding current delay time differences according to the current values of each phase by using the above formula, and therefore, according to the principle that the volt-second product in one switching period is equal, the delay time error can be converted into a terminal voltage error, specifically referring to the following formula:
wherein,
iais the current value of the a phase, ibCurrent value of b phase, icFor the current value of the c-phase, Δ tdelay(ia) Is iaCorresponding current delay time difference, Δ tdelay(ib) Is ibCorresponding current delay time difference, Δ tdelay(ic) Is icCorresponding current delay time difference, tsIs the switching period, V, of the three-phase variable frequency motordcFor dc bus voltage, Δ vAN_delay(ia) Terminal voltage error of a phase, Δ vBN_delay(ib) Terminal voltage error of b-phase, Δ vCN_delay(ic) Is the terminal voltage error of the c-phase.
S42, carrying out coordinate transformation on the terminal voltage error to obtain a voltage compensation value under a α - β coordinate system;
in a specific implementation, the coordinate transformation can be performed by the following formula,
wherein, Vα_compVoltage compensation value of α axis, Vβ_compIs a voltage offset of the β axis.
And S43, correcting the command voltage according to the voltage compensation value under the α - β coordinate system.
It can be understood that after the voltage compensation value is obtained, the command voltage can be corrected according to the voltage compensation value, which is not described herein again.
To facilitate the calculation of the stator flux linkage, in step S50, the stator flux linkage of the permanent magnet synchronous motor may be calculated according to the stator resistance and the corrected command voltage by the following equation,
wherein psiα_estAnd psiβ_estIs the stator flux linkage, V, of the PMSMαAnd VβFor corrected command voltage value, RsIs stator resistance, iαCurrent value of α axis, iβThe current value of the axis β.
Further, as shown in fig. 5, a third embodiment of the method for observing a stator flux linkage of a permanent magnet synchronous motor according to the present invention is proposed based on the first embodiment or the second embodiment, and fig. 5 takes the embodiment based on fig. 2 as an example.
In this embodiment, step S30 specifically includes:
s30': and acquiring the current value of the motor, and determining the corresponding current delay time difference by adopting the linear region according to the current value.
It can be understood that, because a non-linear region with a fast change range may exist in the mapping curve, if the non-linear region is used to determine the current delay time difference, the accuracy of the obtained current delay time difference cannot be guaranteed, and therefore, in this embodiment, the linear region is used to determine the corresponding current delay time difference according to the current value, thereby improving the accuracy of obtaining the current delay time difference.
In a specific implementation, the current delay time difference corresponding to the current value may be directly searched in the linear region, but the efficiency problem of obtaining the current delay time difference is considered.
Referring to fig. 6, the delay time difference can be calculated according to the experimental test result, and the rule of the delay time difference along with the change of the current and the temperature is shown by the solid line in fig. 6 according to the calculation result, wherein the abscissa in the figure is the current value and the ordinate is the delay time difference.
According to the rule in fig. 6, to simplify the calculation, the influence of temperature variations can be ignored, only the influence of current variations is considered, and therefore, the temperature can be selected to have a fixed value T0In a specific implementation T0Can be set as desired, for example at a fixed value T0At 60 ℃ T0A curve corresponding to 60 ℃ is the mapping curve, and accordingly, a block portion in fig. 6 is a linear region of the mapping curve, and accordingly, in this embodiment, the current delay time difference may be determined by the following formula according to the current value, the reference current value of each reference point, and the reference delay time difference,
where i is the present current value, Δ tdelay(i) For the current delay time difference, t (i)1,T0) Is a reference current value i1Corresponding reference delay time difference, t (i)2,T0) Is a reference current value i2Corresponding reference delay time difference, T0Is a preset temperature value.
It should be noted that the dotted line in fig. 6 is a delay time difference obtained by respectively calculating each current value in the block according to the above formula, and it can be understood that the current value needs to be in the linear region to accurately calculate the current delay time difference by using the above formula, and if the current value is not in the linear region, the current delay time difference needs to be determined by using other methods, for example: the determination is performed by directly performing corresponding lookup from the mapping curve, and other manners may also be adopted, which is not limited in this embodiment.
Furthermore, an embodiment of the present invention further provides a computer-readable storage medium, where a permanent magnet synchronous motor stator flux linkage observation program is stored on the computer-readable storage medium, and when executed by a processor, the permanent magnet synchronous motor stator flux linkage observation program implements the following operations:
searching a linear region of a mapping curve, wherein the mapping curve is a curve reflecting the corresponding relation between the delay time difference and the current value;
performing resistance identification based on the linear region of the mapping curve to obtain the stator resistance of the permanent magnet synchronous motor;
acquiring a current value of a motor, and determining a corresponding current delay time difference by adopting a mapping curve according to the current value;
correcting the command voltage according to the current delay time difference;
and calculating the stator flux linkage of the permanent magnet synchronous motor according to the stator resistance and the corrected command voltage.
Further, the permanent magnet synchronous motor stator flux linkage observation program further realizes the following operations when executed by the processor:
calculating a terminal voltage error according to the current delay time difference;
carrying out coordinate transformation on the terminal voltage error to obtain a voltage compensation value under an α - β coordinate system;
and correcting the command voltage according to the voltage compensation value in the α - β coordinate system.
Further, the permanent magnet synchronous motor stator flux linkage observation program further realizes the following operations when executed by the processor:
calculating the stator flux linkage of the permanent magnet synchronous motor according to the stator resistance and the corrected command voltage through the following formula,
wherein psiα_estAnd psiβ_estIs the stator flux linkage, V, of the PMSMαAnd VβFor corrected command voltage value, RsIs stator resistance, iαCurrent value of α axis, iβThe current value of the axis β.
Further, the permanent magnet synchronous motor stator flux linkage observation program further realizes the following operations when executed by the processor:
and acquiring the current value of the motor, and determining the corresponding current delay time difference by adopting the linear region according to the current value.
Further, the permanent magnet synchronous motor stator flux linkage observation program further realizes the following operations when executed by the processor:
and selecting two reference points from the linear area, acquiring a reference current value and a reference delay time difference of each reference point, and determining the current delay time difference according to the current value, the reference current value and the reference delay time difference of each reference point.
Further, the permanent magnet synchronous motor stator flux linkage observation program further realizes the following operations when executed by the processor:
selecting a current value in the linear region;
taking the selected current value as a direct-axis current value injected into the permanent magnet synchronous motor, and detecting a direct-axis voltage value corresponding to the direct-axis current value;
and calculating the stator resistance of the permanent magnet synchronous motor according to the direct-axis current value and the corresponding direct-axis voltage value.
Further, the permanent magnet synchronous motor stator flux linkage observation program further realizes the following operations when executed by the processor:
and acquiring the tangent slope of each point on the mapping curve, and determining the linear region according to the tangent slope.
Further, the permanent magnet synchronous motor stator flux linkage observation program further realizes the following operations when executed by the processor:
taking a point where the slope of the tangent line is equal to a preset slope as a segmentation point;
dividing the mapping curve according to the dividing points to obtain at least two dividing areas;
and judging whether each partition area has a point with a tangent slope larger than a preset slope or not, and taking the partition area without the point with the tangent slope larger than the preset slope as the linear area.
According to the scheme, the linear region of the mapping curve is searched, resistance identification is carried out on the basis of the linear region of the mapping curve, the stator resistance of the permanent magnet synchronous motor is obtained, the current value of the motor is obtained, the corresponding current delay time difference is determined by the mapping curve according to the current value, the command voltage is corrected according to the current delay time difference, the stator flux linkage of the permanent magnet synchronous motor is calculated according to the stator resistance and the corrected command voltage, the adopted stator resistance and the command voltage are more accurate, and therefore the stator flux linkage is more accurate.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) as described above and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, an air conditioner, or a network device) to execute the method according to the embodiments of the present invention.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (9)
1. A permanent magnet synchronous motor stator flux linkage observation method is characterized by comprising the following steps:
searching a linear region of a mapping curve, wherein the mapping curve is a curve reflecting the corresponding relation between the delay time difference and the current value;
performing resistance identification based on the linear region of the mapping curve to obtain the stator resistance of the permanent magnet synchronous motor;
acquiring a current value of the motor, and determining a corresponding current delay time difference by adopting a linear region of a mapping curve according to the current value;
correcting the command voltage according to the current delay time difference;
calculating a stator flux linkage of the permanent magnet synchronous motor according to the stator resistance and the corrected command voltage;
the delay time difference is the difference value between the turn-off delay time and the turn-on delay time of a switching device of the motor frequency converter.
2. The method of claim 1, wherein the correcting the command voltage according to the current delay time difference comprises:
calculating a terminal voltage error according to the current delay time difference;
carrying out coordinate transformation on the terminal voltage error to obtain a voltage compensation value under an α - β coordinate system;
and correcting the command voltage according to the voltage compensation value in the α - β coordinate system.
3. The method of claim 2, wherein the stator flux linkage of the permanent magnet synchronous machine is calculated based on the stator resistance and the corrected command voltage by the following equation,
wherein psiα_estAnd psiβ_estIs the stator flux linkage, V, of the PMSMαAnd VβFor corrected command voltage value, RsIs stator resistance, iαCurrent value of α axis, iβThe current value of the axis β.
4. The method of claim 1, wherein the determining the corresponding current delay time difference using the linear region according to the current value specifically comprises:
and selecting two reference points from the linear area, acquiring a reference current value and a reference delay time difference of each reference point, and determining the current delay time difference according to the current value, the reference current value and the reference delay time difference of each reference point.
5. The method according to any one of claims 1 to 3, wherein the obtaining of the stator resistance of the permanent magnet synchronous motor by performing resistance identification based on the linear region of the mapping curve specifically comprises:
selecting a current value in the linear region;
taking the selected current value as a direct-axis current value injected into the permanent magnet synchronous motor, and detecting a direct-axis voltage value corresponding to the direct-axis current value;
and calculating the stator resistance of the permanent magnet synchronous motor according to the direct-axis current value and the corresponding direct-axis voltage value.
6. The method according to any one of claims 1 to 3, wherein the searching for the linear region of the mapping curve specifically comprises:
and acquiring the tangent slope of each point on the mapping curve, and determining the linear region according to the tangent slope.
7. The method according to claim 6, wherein determining the linear region from the tangent slope comprises:
taking a point where the slope of the tangent line is equal to a preset slope as a segmentation point;
dividing the mapping curve according to the dividing points to obtain at least two dividing areas;
and judging whether each partition area has a point with a tangent slope larger than a preset slope or not, and taking the partition area without the point with the tangent slope larger than the preset slope as the linear area.
8. A flux linkage observer, characterized in that the flux linkage observer comprises: a memory, a processor and a PMSM stator flux linkage observation program stored on the memory and executable on the processor, the PMSM stator flux linkage observation program being configured to implement the steps of the PMSM stator flux linkage observation method of any one of claims 1-7.
9. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a permanent magnet synchronous motor stator flux linkage observation program that, when executed by a processor, implements the steps of the permanent magnet synchronous motor stator flux linkage observation method according to any one of claims 1 to 7.
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