Control method and control device of permanent magnet synchronous motor
阅读说明：本技术 永磁同步电机的控制方法和控制装置 (Control method and control device of permanent magnet synchronous motor ) 是由 蒋元广 刘兵 陈晨 李占江 李麟 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种永磁同步电机的控制方法和装置,其中,方法包括以下步骤：获取转矩指令、永磁同步电机的转速和弱磁电压余量,其中,弱磁电压余量根据d轴电压指令和q轴电压指令计算得到；根据转矩指令、转速和弱磁电压余量生成d轴电流指令和q轴电流指令；根据d轴电流指令和q轴电流指令采用电流单闭环矢量控制技术对永磁同步电机进行控制。该方法根据转矩指令、永磁同步电机的转速和弱磁电压余量对永磁同步电机进行控制,有助于提高电流检测信噪比和电流检测精度,从而提高电机控制的稳定性,降低电机控制系统成本。(The invention discloses a control method and a control device of a permanent magnet synchronous motor, wherein the method comprises the following steps: acquiring a torque command, the rotating speed of the permanent magnet synchronous motor and flux weakening voltage allowance, wherein the flux weakening voltage allowance is obtained by calculation according to a d-axis voltage command and a q-axis voltage command; generating a d-axis current instruction and a q-axis current instruction according to the torque instruction, the rotating speed and the flux weakening voltage margin; and controlling the permanent magnet synchronous motor by adopting a current single closed loop vector control technology according to the d-axis current instruction and the q-axis current instruction. The method controls the permanent magnet synchronous motor according to the torque command, the rotating speed of the permanent magnet synchronous motor and the flux weakening voltage margin, and is beneficial to improving the current detection signal-to-noise ratio and the current detection precision, so that the stability of motor control is improved, and the cost of a motor control system is reduced.)
1. A control method of a permanent magnet synchronous motor is characterized by comprising the following steps:
acquiring a torque command, the rotating speed of the permanent magnet synchronous motor and flux weakening voltage allowance, wherein the flux weakening voltage allowance is obtained by calculation according to a d-axis voltage command and a q-axis voltage command;
generating a d-axis current instruction and a q-axis current instruction according to the torque instruction, the rotating speed and the flux weakening voltage margin;
and controlling the permanent magnet synchronous motor by adopting a current single closed loop vector control technology according to the d-axis current instruction and the q-axis current instruction.
2. The method of controlling a permanent magnet synchronous motor according to claim 1, wherein the generating a dq-axis current command based on the torque command, the rotation speed, and the field weakening voltage margin comprises:
respectively searching a maximum torque current ratio table, a maximum torque voltage ratio table and a constant current torque table according to the torque command and the rotating speed to correspondingly obtain three groups of dq axis current values
and selecting one group from the three groups of dq-axis current values according to the flux weakening voltage margin to serve as the d-axis current command and the q-axis current command.
3. The control method of a permanent magnet synchronous motor according to claim 2, wherein said selecting one of said three sets of dq-axis current values as said d-axis current command and said q-axis current command based on a field weakening voltage margin comprises:
computing
calculating the amplitude IsAnd the minimum current threshold I allowed to flow in the permanent magnet synchronous motorsetThe difference between the flux-weakening voltage margin and the flux-weakening voltage threshold is recorded as a first difference, and the difference between the flux-weakening voltage margin and the flux-weakening voltage threshold is calculated and recorded as a second difference;
if the first difference is greater than 0 and the second difference is greater than 0, then it will be
if the first difference is less than or equal to 0 and the second difference is greaterAt 0, then will
if the second difference is less than or equal to 0, then
4. The control method of the permanent magnet synchronous motor according to claim 2, wherein the calibrating step of the constant current torque converter comprises:
step 1: according to the minimum current threshold I allowed to flow in the permanent magnet synchronous motorsetCalculating a dq axis current command according to the dq axis current included angle sigma, wherein the d axis current command id_ref＝-Isetcos σ, q-axis current command iq_ref＝Isetsinσ；
Step 2: controlling the permanent magnet synchronous motor by adopting a current single closed loop vector control technology so as to enable a d-axis current feedback value idAnd id_refConsistent, q-axis current feedback value iqAnd iq_refThe consistency is achieved;
and step 3: according to a predetermined torque gradient Delta TrefIncrease torque command TrefWherein the torque command TrefIs 0;
and 4, step 4: obtaining the rotating speed and torque feedback value T of the permanent magnet synchronous motorfdbAccording to the torque command TrefAnd said torque feedback value TfdbAdjusting the current included angle sigma of the dq axis, and returning to the step 1;
wherein the torque command T in each cyclerefSpeed n, dq axis current command id_refAnd iq_refAnd forming the constant current variable torque meter.
5. The control method of a permanent magnet synchronous motor according to claim 4, characterized in thatCharacterized in that said torque command T is based onrefAnd a torque feedback value TfdbAdjusting the dq-axis current included angle sigma comprises:
judgment of TrefAnd TfdbThe magnitude relationship between them;
if T isref>TfdbIncreasing the current included angle sigma of the dq axis according to the preset angle gradient delta sigma;
if T isref＜TfdbReducing the current included angle sigma of the dq axis according to the preset angle gradient delta sigma until Tref＝Tfdb；
Wherein if the dq-axis current included angle sigma is in the adjusting process of the range of 0-90 DEG, TrefIs always greater than TfdbAnd stopping the calibration of the constant current torque meter.
6. The control method of a permanent magnet synchronous motor according to claim 1, wherein the field weakening voltage margin is calculated according to the following formula:
wherein, Delta U is the flux weakening voltage margin, UdcIs the supply voltage on the DC side of the inverter, ud、uqThe d-axis voltage command and the q-axis voltage command are provided.
7. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out a method of controlling a permanent magnet synchronous machine according to any one of claims 1-6.
8. A control device of a permanent magnet synchronous motor, characterized by comprising:
the voltage margin calculation module is used for acquiring a power supply voltage and a dq axis voltage instruction at the direct current side of the inverter and calculating to obtain the flux weakening voltage margin according to the power supply voltage and the dq axis voltage instruction;
the current instruction generating module is used for acquiring a torque instruction, the rotating speed of the permanent magnet synchronous motor and the flux weakening voltage allowance and generating a dq current instruction according to the torque instruction, the rotating speed and the flux weakening voltage allowance;
and the control module is used for controlling the permanent magnet synchronous motor by adopting a current single closed loop vector control technology according to the d-axis current instruction and the q-axis current instruction.
9. The control device of a permanent magnet synchronous motor according to claim 8, wherein the current command generation module is specifically configured to:
respectively searching a maximum torque current ratio table, a maximum torque voltage ratio table and a constant current torque table according to the torque command and the rotating speed to correspondingly obtain three groups of dq axis current values
and selecting one group from the three groups of dq-axis current values according to the flux weakening voltage margin to serve as the d-axis current command and the q-axis current command.
10. The control device of a permanent magnet synchronous motor according to claim 9, wherein the current command generating module is configured to select one of the three sets of dq-axis current values as the d-axis current command and the q-axis current command according to a field weakening voltage margin, and is specifically configured to:
computing
calculating the amplitude IsAnd said elementMinimum current threshold I allowed to flow in a magnetic synchronous machinesetThe difference between the flux-weakening voltage margin and the flux-weakening voltage threshold is recorded as a first difference, and the difference between the flux-weakening voltage margin and the flux-weakening voltage threshold is calculated and recorded as a second difference;
if the first difference is greater than 0 and the second difference is greater than 0, then it will be
if the first difference is less than or equal to 0 and the second difference is greater than 0, then it will be
if the second difference is less than or equal to 0, then
Technical Field
The invention relates to the technical field of motors, in particular to a control method and a control device of a permanent magnet synchronous motor.
Background
In recent years, a permanent magnet synchronous motor is widely applied to the fields of industrial manufacturing, new energy automobiles and the like by virtue of the characteristics of high efficiency, excellent control performance, wide speed regulation range and the like. In practical application, in order to fully exert the power of the permanent magnet synchronous motor, a control mode of combining a maximum torque current ratio with a maximum torque voltage ratio is often adopted, and when the motor runs below a base speed, a current instruction is obtained by searching a maximum torque current ratio table and current closed-loop control is carried out; when the motor runs above the basic speed, a current instruction is obtained by searching the maximum torque-voltage ratio table and current closed-loop control is carried out.
In an actual system, because the measuring range of the current sensor needs to cover the maximum current of the motor operation, the current sensor has a large error and a low signal-to-noise ratio when detecting a small current, so that the motor has large torque pulsation and poor stability when a small torque command is requested. For this reason, the use of a higher-precision current sensor in the related art can improve the detection precision of a small current, but this significantly increases the system cost.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, a first objective of the present invention is to provide a method for controlling a permanent magnet synchronous motor, so as to control the permanent magnet synchronous motor according to a torque command, a rotation speed of the permanent magnet synchronous motor, and a flux weakening voltage margin, which is helpful for improving a current detection signal-to-noise ratio and a current detection precision, thereby improving stability of motor control and reducing cost of a motor control system.
A second object of the invention is to propose a computer-readable storage medium.
A third object of the present invention is to provide a control device for a permanent magnet synchronous motor.
In order to achieve the above object, an embodiment of a first aspect of the present invention provides a control method for a permanent magnet synchronous motor, including the following steps: acquiring a torque command, the rotating speed of the permanent magnet synchronous motor and flux weakening voltage allowance, wherein the flux weakening voltage allowance is obtained by calculation according to a d-axis voltage command and a q-axis voltage command; generating a d-axis current instruction and a q-axis current instruction according to the torque instruction, the rotating speed and the flux weakening voltage margin; and controlling the permanent magnet synchronous motor by adopting a current single closed loop vector control technology according to the d-axis current instruction and the q-axis current instruction.
According to the control method of the permanent magnet synchronous motor, a torque instruction, the rotating speed of the permanent magnet synchronous motor and the flux weakening voltage allowance are obtained firstly, then a d-axis current instruction and a q-axis current instruction are generated according to the torque instruction, the rotating speed and the flux weakening voltage allowance, and finally the permanent magnet synchronous motor is controlled by adopting a current single closed loop vector control technology according to the d-axis current instruction and the q-axis current instruction. Therefore, the permanent magnet synchronous motor is controlled according to the torque command, the rotating speed of the permanent magnet synchronous motor and the flux weakening voltage margin, the current detection signal-to-noise ratio and the current detection precision are improved, the motor control stability is improved, and the motor control system cost is reduced.
In addition, the control method of the permanent magnet synchronous motor according to the embodiment of the invention may further have the following additional technical features:
according to an embodiment of the present invention, the generating a dq-axis current command based on the torque command, the rotation speed, and the field weakening voltage margin includes: respectively searching a maximum torque current ratio table, a maximum torque voltage ratio table and a constant current torque table according to the torque command and the rotating speed to correspondingly obtain three groups of dq axis current values
According to an embodiment of the present invention, the selecting one set from the three sets of dq-axis current values as the d-axis current command and the q-axis current command according to a field weakening voltage margin includes: computing
According to an embodiment of the present invention, the calibrating step of the constant current torque meter comprises:
step 1: according to the minimum current threshold I allowed to flow in the permanent magnet synchronous motorsetCalculating a dq axis current instruction according to the dq axis current included angle sigma, wherein the d axis circuit instruction id_ref＝-Isetcos σ, q-axis current command iq_ref＝Isetsinσ；
Step 2: controlling the permanent magnet synchronous motor by adopting a current single closed loop vector control technology so as to enable a d-axis current feedback value idAnd id_refConsistent, q-axis current feedback value iqAnd iq_refUniformity；
And step 3: according to a predetermined torque gradient Delta TrefIncrease torque command TrefWherein the torque command TrefIs 0;
and 4, step 4: obtaining the rotating speed and torque feedback value T of the permanent magnet synchronous motorfdbAccording to the torque command TrefAnd said torque feedback value TfdbAdjusting the current included angle sigma of the dq axis, and returning to the
wherein the torque command T in each cyclerefSpeed n, dq axis current command id_refAnd iq_refAnd forming the constant current variable torque meter.
According to one embodiment of the invention, the torque command T is based onrefAnd a torque feedback value TfdbAdjusting the dq-axis current included angle sigma comprises: judgment of TrefAnd TfdbThe magnitude relationship between them; if T isref>TfdbIncreasing the current included angle sigma of the dq axis according to the preset angle gradient delta sigma; if T isref＜TfdbReducing the current included angle sigma of the dq axis according to the preset angle gradient delta sigma until Tref＝Tfdb(ii) a Wherein if the dq-axis current included angle sigma is in the adjusting process of the range of 0-90 DEG, TrefIs always greater than TfdbAnd stopping the calibration of the constant current torque meter.
According to an embodiment of the present invention, the field weakening voltage margin is calculated according to the following formula:
Further, an embodiment of the second aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the control method for the permanent magnet synchronous motor provided in the embodiment of the first aspect of the present invention.
The computer readable storage medium of the embodiment of the invention can control the permanent magnet synchronous motor according to the torque instruction, the rotating speed of the permanent magnet synchronous motor and the flux weakening voltage margin when the computer program stored on the computer readable storage medium is executed by the processor, and is beneficial to improving the current detection signal-to-noise ratio and the current detection precision, thereby improving the stability of motor control and reducing the cost of a motor control system.
In order to achieve the above object, a third embodiment of the present invention provides a control device for a permanent magnet synchronous motor, including: the voltage margin calculation module is used for acquiring a power supply voltage and a dq axis voltage instruction at the direct current side of the inverter and calculating to obtain the flux weakening voltage margin according to the power supply voltage and the dq axis voltage instruction; the current instruction generating module is used for acquiring a torque instruction, the rotating speed of the permanent magnet synchronous motor and the flux weakening voltage allowance and generating a dq current instruction according to the torque instruction, the rotating speed and the flux weakening voltage allowance; and the control module is used for controlling the permanent magnet synchronous motor by adopting a current single closed loop vector control technology according to the d-axis current instruction and the q-axis current instruction.
According to the control device of the permanent magnet synchronous motor, the permanent magnet synchronous motor is controlled according to the torque command, the rotating speed of the permanent magnet synchronous motor and the flux weakening voltage margin, and the current detection signal-to-noise ratio and the current detection precision are improved, so that the stability of motor control is improved, and the cost of a motor control system is reduced.
In addition, the control device of the permanent magnet synchronous motor according to the embodiment of the present invention may further have the following additional technical features:
according to an embodiment of the present invention, the current instruction generating module is specifically configured to: respectively searching a maximum torque current ratio table, a maximum torque voltage ratio table and a constant current torque table according to the torque command and the rotating speed to correspondingly obtain three groups of dq axis current values
According to an embodiment of the present invention, the current instruction generating module is specifically configured to, when selecting one set from the three sets of dq-axis current values as the d-axis current instruction and the q-axis current instruction according to a flux weakening voltage margin: computing
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
Fig. 1 is a flowchart of a control method of a permanent magnet synchronous motor according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a control method of a permanent magnet synchronous motor according to an example of the present invention;
FIG. 3 is a schematic diagram of generating three sets of dq axis current values according to one example of the invention;
FIG. 4 is a schematic diagram of a calibrated constant current torque meter according to an example of the present invention;
fig. 5 is a block diagram of a control apparatus of a permanent magnet synchronous motor according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
A control method and apparatus of a permanent magnet synchronous motor according to an embodiment of the present invention will be described below with reference to the accompanying drawings.
Fig. 1 is a flowchart of a control method of a permanent magnet synchronous motor according to an embodiment of the present invention.
It should be noted that, in this embodiment, a two-phase stationary coordinate system α - β may be defined, a two-phase rotating coordinate system d-q is established on the rotor of the permanent magnet synchronous motor, and the coordinate system d-q and the rotor rotate synchronously, where the d axis is a direction of the rotor magnetic field, and the q axis is a direction perpendicular to the rotor magnetic field. The position of the rotor of the permanent magnet synchronous motor can be defined as theta.
In this embodiment, an MTPA (Maximum Torque Per amp, Maximum Torque current ratio) table, a Maximum Torque Voltage ratio MTPV (Maximum Torque Per Voltage) table and a constant current Torque table may be set, where the Maximum Torque current ratio table is for the purpose of setting a certain current amplitude and adjusting a dq axis current included angle to find a Maximum Torque current ratio point, and further calibrating a corresponding relationship table of the obtained motor Torque, rotation speed and dq axis current; the maximum torque voltage ratio table is a table of corresponding relations between motor torque, rotating speed and dq axis current, which is obtained by calibrating, namely setting a certain current amplitude and flux weakening voltage allowance, adjusting a dq axis current included angle, seeking a maximum torque voltage ratio point on the premise of meeting the flux weakening voltage allowance.
That is, the maximum torque current ratio table and the maximum torque voltage ratio table are searched for from the torque command and the rotation speed, and the dq-axis current at the maximum torque ratio and the maximum torque voltage ratio can be obtained.
As shown in fig. 1, the control method of the permanent magnet synchronous motor includes the steps of:
s101, a torque command, the rotating speed of the permanent magnet synchronous motor and flux weakening voltage allowance are obtained, wherein the flux weakening voltage allowance is obtained through calculation according to a d-axis voltage command and a q-axis voltage command.
Wherein, weak magnetic voltage margin is calculated according to the following formula:
Specifically, as shown in fig. 2, when the permanent magnet synchronous motor control is started, a torque command T input by a user may be acquiredrefThe rotating speed n of the permanent magnet synchronous motor and the flux weakening voltage margin delta U are both 0. That is, the torque command T acquired when the permanent magnet synchronous motor control is startedrefThe torque instruction received by the permanent magnet synchronous motor, the rotating speed n is 0, and the flux weakening voltage margin delta U is the power supply voltage U at the DC side of the inverterdc。
And S102, generating a d-axis current command and a q-axis current command according to the torque command, the rotating speed and the flux weakening voltage margin.
In one example, as shown in FIG. 3, based on torque command TrefGenerating the dq-axis current command by the rotation speed n and the flux weakening voltage margin delta U may include: according to the torque command TrefAnd the rotating speed n is respectively searched for a maximum torque current ratio table, a maximum torque voltage ratio table and a constant current torque table, and three groups of dq axis current values are correspondingly obtained
Further, selecting one of the three sets of dq-axis current values as the d-axis current command and the q-axis current command according to the flux weakening voltage margin may include: computing
Specifically, as shown in fig. 3, first, according to the torque command T acquired in step S101, the torque command T is acquiredrefSearching an MTPA table by the rotating speed n to obtain a dq axis current instruction corresponding to the maximum torque current ratioAnd input to port No. 1 of the two-way selector switch S1; according to the torque command T acquired in step S101refSearching an MTPV table by the rotating speed n to obtain a dq axis current instruction corresponding to the maximum torque voltage ratio
then, by the formula
Finally, referring to FIG. 3, two-way selector switch S1 and two-way selector switch S2 each pass through the respective Port 2 signals (the respective first difference Δ I)sAnd a second difference value DeltaUs) Operates to select an optimal set of dq-axis current commands as an optimal d-axis current command id_refAnd q-axis current command iq_refFor the two-way selection switch S1, if the signal of port No. 2 is greater than 0, the dq axis current value of port No. 1 is output, and otherwise, the dq axis current value of port No. 3 is output; for the two-way selector switch S2, if the signal of port No. 2 is greater than 0, the dq axis current value of port No. 1 is output, and conversely, the dq axis current value of port No. 3 is output, and the control process is described as follows:
if Δ Is>0, the two-way selection switch S1 outputs the dq-axis current command of the No. 1 port
If Δ IsIf the current is less than or equal to 0, the two-way selection switch S1 outputs a dq-axis current instruction of the No. 3 port
If Δ UsIf the current is less than or equal to 0, the two-way selection switch S2 outputs the dq-axis current instruction of the No. 3 port
And S103, controlling the permanent magnet synchronous motor by adopting a current single closed loop vector control technology according to the d-axis current instruction and the q-axis current instruction.
Specifically, referring to fig. 2, after the execution of step 102 is finished, the dq-axis current command i is obtainedd_ref、iq_refThen, according to the dq-axis current fingerLet id_ref、iq_refControlling the permanent magnet synchronous motor may include the steps of:
step 1031, commanding d-axis current id_refAnd d-axis current feedback value idTaking the difference to obtain the d-axis current deviation delta idThe deviation is regulated by PI to obtain d-axis voltage command ud(ii) a The q-axis current command iq_refAnd q-axis current feedback value iqTaking difference to obtain q-axis current deviation delta iqThe deviation is regulated by PI to obtain a q-axis voltage command uq. Wherein, the feedback value i of the dq axis currentdAnd iqMay be 0.
Step 1032, according to the power supply voltage U of the DC side of the inverterdcD-axis voltage command udAnd q-axis voltage command uqCalculating the flux weakening voltage margin DeltaU, i.e. according to the formulaAnd calculating the flux weakening voltage margin delta U, and updating the magnetic voltage margin delta U for use in subsequent cycle control.
1033, according to the rotor position theta, the dq axis voltage command u is processeddAnd uqInverse PARK transform (PARK-1) is carried out to obtain alpha and beta axis voltage uαAnd uβ. The initial value of the rotor position theta is 0, and in the subsequent cycle control, the rotor position theta can be detected and output in the operation process of the PMSM through the position sensor.
1034, according to the α β axis voltage uαAnd uβAnd generating six paths of driving signals D by adopting an SVPWM (Space Vector Pulse width modulation) technology so that the inverter drives the PMSM to operate according to the six paths of driving signals D.
In step 1035, during the operation of the PMSM, the position sensor detects the rotor position and outputs the rotor position θ and the rotation speed n.
Step 1036, detecting three-phase current i of the permanent magnet synchronous motorA、iBAnd iCAnd the three-phase current is converted by CLARKE to obtain alpha and beta axis current iαAnd iβ。
Step 1037, according to the rotor position theta obtained in step 5 to the alpha and beta axis current iαAnd iβCarrying out PARK conversion to obtain a dq axis current feedback value idAnd iq。
That is, the steps 5 to 7 are all to detect the feedback value in the operation process of the PMSM: rotor position theta, rotating speed n and dq axis current feedback value idAnd iqTo the alpha beta axis current i according to the rotor position thetaαAnd iβCarrying out PARK conversion to obtain a dq axis current feedback value idAnd iqTo be used for the next control (according to i)dAnd iqCalculate the first difference and the second difference, calculate the dq-axis current command based on the rotation speed n).
In summary, in this embodiment, three control modes can be performed on the permanent magnet synchronous motor: according to dq-axis current command
Therefore, the control method controls the permanent magnet synchronous motor according to the torque command, the rotating speed of the permanent magnet synchronous motor and the flux weakening voltage margin, does not need a current sensor with higher precision, and can improve the current detection signal-to-noise ratio and the current detection precision, thereby improving the stability of motor control and reducing the cost of a motor control system.
In one example of the present invention, as shown in fig. 4, the calibration step of the constant current torque meter may include:
step 1: according to the minimum current threshold I allowed to flow in the permanent magnet synchronous motorsetCalculating a dq axis current command according to the dq axis current included angle sigma, wherein the d axis current command id_ref＝-Isetcos σ, q-axis current command iq_ref＝IsetAnd sin sigma. It should be noted that the dq-axis current included angle σ may be set according to a specific actual situation, and is not limited herein.
Step 2: the permanent magnet synchronous motor is controlled by adopting a current single closed loop vector control technology so as to enable a d-axis current feedback value idAnd id_refConsistent, q-axis current feedback value iqAnd iq_refAnd (5) the consistency is achieved.
Specifically, referring to fig. 4, dq-axis current command i is calculatedd_ref、iq_refThen, first, the d-axis current command i can be setd_refAnd d-axis current feedback value idTaking the difference to obtain the d-axis current deviation delta idThe deviation is regulated by PI to obtain d-axis voltage command ud(ii) a The q-axis current command iq_refAnd q-axis current feedback value iqTaking difference to obtain q-axis current deviation delta iqThe deviation is regulated by PI to obtain a q-axis voltage command uqWherein the dq-axis current feedback value idAnd iqAll of which can be 0; then, a dq-axis voltage command u is given according to the rotor position θdAnd uqPerforming inverse PARK transform (PARK)-1) Obtain alpha beta axis voltage uαAnd uβ. Wherein the initial value of the rotor position θ is 0; finally, according to the alpha beta axis voltage uαAnd uβControlling the permanent magnet synchronous motor, and detecting three-phase current i in the operation process of the permanent magnet synchronous motorA、iBAnd iCAnd the three-phase current is converted by CLARKE to obtain alpha and beta axis current iαAnd iβAnd detecting the rotor position theta to the alpha beta axis current i according to the rotor position thetaαAnd iβCarrying out PARK conversion to obtain a dq axis current feedback value idAnd iqControlling in such a way that the control is circulated until idAnd id_refConsistent, q-axis current feedback value iqAnd iq_refAnd (5) the consistency is achieved.
And step 3: according to a predetermined torque gradient Delta TrefIncrease torque command TrefWherein the torque command TrefIs 0.
And 4, step 4: acquiring the rotating speed n and the torque feedback value T of the permanent magnet synchronous motorfdbAccording to the torque command TrefAnd a torque feedback value TfdbAnd adjusting the dq-axis current included angle sigma and returning to the
Wherein the torque command T in each cyclerefSpeed n, dq axis current command id_refAnd iq_refAnd forming a constant current torque meter.
Further, according to the torque command TrefAnd a torque feedback value TfdbAdjusting the dq-axis current included angle sigma comprises: judgment of TrefAnd TfdbThe magnitude relationship between them; if T isref>TfdbIncreasing the current included angle sigma of the dq axis according to the preset angle gradient delta sigma; if T isref＜TfdbReducing the current included angle sigma of the dq axis according to the preset angle gradient delta sigma until Tref＝Tfdb(ii) a Wherein if the dq-axis current included angle sigma is in the adjusting process of the range of 0-90 DEG, TrefIs always greater than TfdbThen, the calibration of the constant current variable torque meter is stopped to ensure that the current flowing through the motor winding is not less than the minimum current threshold I when the torque is smallerset。
In summary, the control method of the permanent magnet synchronous motor according to the embodiment of the present invention controls the permanent magnet synchronous motor according to the torque command, the rotation speed of the permanent magnet synchronous motor, and the flux weakening voltage margin, and can ensure that the current flowing through the motor winding is not less than the minimum current threshold when the torque is small through the constant current change torque control, and can improve the current detection signal-to-noise ratio and the current detection precision, thereby improving the stability of the motor control; the motor control system does not need a current sensor with higher precision, and can reduce the cost of the motor control system compared with the method that the detection precision of small current is improved through the current sensor with higher precision.
Further, the present invention proposes a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the control method of the permanent magnet synchronous motor described above.
When the computer program corresponding to the control method of the permanent magnet synchronous motor stored on the computer readable storage medium is executed by a processor, the current detection signal-to-noise ratio and the current detection precision can be improved through the constant current torque control, so that the stability of motor control is improved, and the cost of a motor control system is reduced.
Fig. 5 is a control device of a permanent magnet synchronous motor according to an embodiment of the present invention.
As shown in fig. 5, the control device 100 for a permanent magnet synchronous motor includes: the device comprises a voltage margin calculation module 10, a current instruction generation module 20 and a control module 30.
The voltage margin calculation module 10 is configured to obtain a power voltage at a dc side of the inverter and a dq-axis voltage command, and calculate a flux weakening voltage margin according to the power voltage and the dq-axis voltage command; the current instruction generating module 20 is configured to obtain a torque instruction, a rotation speed of the permanent magnet synchronous motor, and a flux weakening voltage margin, and generate a dq current instruction according to the torque instruction, the rotation speed, and the flux weakening voltage margin; the control module 30 is configured to control the permanent magnet synchronous motor by using a current single closed-loop vector control technique according to the d-axis current instruction and the q-axis current instruction.
In an embodiment of the present invention, the current instruction generating module 20 may specifically be configured to: respectively searching a maximum torque current ratio table, a maximum torque voltage ratio table and a constant current torque table according to the torque command and the rotating speed to correspondingly obtain three groups of dq axis current values
Further, the current instruction generating module 20 may select one set from the three sets of dq-axis current values according to the flux weakening voltage margin, and when the selected set is used as the d-axis current instruction and the q-axis current instruction, the current instruction generating module is specifically configured to: computingAmplitude of (I)sWherein, in the step (A),calculating the amplitude IsMinimum current threshold I allowed to flow in permanent magnet synchronous motorsetThe difference between the two is recorded as a first difference, and the difference between the flux weakening voltage margin and the flux weakening voltage threshold is calculated and recorded as a second difference; if the first difference is greater than 0 and the second difference is greater than 0, then it will be
It should be noted that, for other specific embodiments of the control device of the permanent magnet synchronous motor according to the embodiment of the present invention, reference may be made to the specific embodiment of the control method of the permanent magnet synchronous motor according to the present invention, and details are not described here again.
The control device of the permanent magnet synchronous motor provided by the embodiment of the invention can improve the current detection signal-to-noise ratio and the current detection precision through the constant current torque control, thereby improving the stability of motor control and reducing the cost of a motor control system.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
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