CN115173767A - Method for correcting estimated torque of motor - Google Patents
Method for correcting estimated torque of motor Download PDFInfo
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- CN115173767A CN115173767A CN202210713028.4A CN202210713028A CN115173767A CN 115173767 A CN115173767 A CN 115173767A CN 202210713028 A CN202210713028 A CN 202210713028A CN 115173767 A CN115173767 A CN 115173767A
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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
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
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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
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
- H02P21/20—Estimation of torque
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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
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
- H02P25/022—Synchronous motors
-
- 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
- H02P2207/00—Indexing scheme relating to controlling arrangements characterised by the type of motor
- H02P2207/05—Synchronous machines, e.g. with permanent magnets or DC excitation
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The invention discloses a method for correcting the estimated torque of a motor, which is characterized by comprising the following steps of: s1: presetting a plurality of rotating speed sampling points on a motor, acquiring motor parameters of each sampling point, calculating a flux linkage through a flux linkage calculation formula according to the motor parameters, and calibrating the dynamic flux linkage; s2: when the motor is in a preset working condition, different input combinations of the quadrature-axis current and the direct-axis current are given to obtain an estimated torque value; s4: and outputting three calibration data tables for correcting the estimated torque in the motor control software, and finally outputting the optimized estimated torque. According to the method, a formula method of the non-constant inductance difference value and a mode of actually estimating the torque coefficient compensation are adopted to improve the torque estimation precision, the torque estimation is corrected, the torque estimation precision is improved, and the torque control and system decision of the whole vehicle can be better supported.
Description
Technical Field
The invention relates to the technical field of new energy automobiles, in particular to a method for correcting estimated torque in the field of permanent magnet synchronous motor control.
Background
Pure electric vehicleThe vehicle is driven by the motor to drive the wheels, and the application of the permanent magnet synchronous motor is mainly used at present. The core of permanent magnet synchronous motor control is to output larger torque to reach higher rotating speed as much as possible within the constraints of direct current voltage and voltage utilization rate. Therefore, a reasonable combination of the quadrature-axis current command and the direct-axis current command needs to be found for control to achieve the expected performance target. Generally, a permanent magnet synchronous motor is calibrated on a motor rack before being applied to a vehicle, and the most important operation is to test the corresponding relation between the output current and the output torque of a controller on the rack on the premise of giving full play to the performance of the motor. And the motor controller performs actual torque estimation while responding to a torque request of the torque vehicle controller, compares the actual torque with the required execution torque, and feeds back the actual torque to the vehicle controller for decision and control of a vehicle command. The current torque estimation method of the permanent magnet synchronous motor is mainly characterized in that the output torque of the motor is directly calculated through monitored motor parameters, the working power of the motor cannot be accurately calculated, and the working temperature inside the motor changes, so that the calculation is not accurate enough, while the electromagnetic torque formula of the permanent magnet synchronous motor is a formula in an ideal state, and the electromagnetic torque formula is expressed by a direct-alternating-current axis in the ideal state:the torque of the motor is obtained through a formula by adopting a non-mean value flux linkage calculation method, but the formula is an ideal formula, motor parameters change along with the use condition of the motor, and the internal temperature is in a constantly changing state along with the working time of the motor, so that the torque value estimated through the formula is inaccurate, and the judgment of the vehicle running condition is influenced. The Chinese patent with application patent number CN202110681444.6 discloses a method, a system and a vehicle for estimating the motor torque of an electric vehicle, wherein the patent mentions that an ideal formula can be influenced by the running condition of the motor, the motor parameters change along with the change of the using condition, the temperature and the like of the motor, and the change of the data can influence the accuracy of the estimated torque, and is characterized in that the change value and the repair value of a magnetic chain are obtainedMotor torque estimation is being performed.
However, the method, the system and the vehicle for estimating the motor torque of the electric vehicle only consider the influence of the flux linkage on the torque, so the torque estimated by the technical scheme disclosed in the chinese patent with the application patent number CN202110681444.6 is not high in accuracy.
Disclosure of Invention
The invention mainly solves the problem of poor torque estimation precision in motor control in the prior art, and provides a method for correcting the estimated torque of a motor, wherein the current torque estimation method of the permanent magnet synchronous motor mostly refers to a permanent magnet synchronous motor electromagnetic torque formula, and the torque estimation method is represented by an alternating-direct axis system as follows:the formula is an ideal formula, and the estimated torque can be consistent with the target torque only by accurate motor parameters. The current permanent magnet synchronous motor torque estimation method adopts a non-mean value flux linkage calculation method, but the method ignores the influence caused by the change of the difference value of the inductance of the alternating current axis and the direct current axis of the reluctance torque part. In the conventional calibration method, the quadrature-direct axis inductance is constant, and cannot well cope with torque estimation under different input conditions. The invention improves the torque estimation precision by adopting a formula method of the non-constant inductance difference value and matching with an actual estimation torque coefficient compensation mode.
The technical problem of the invention is mainly solved by the following technical scheme: a method of estimating a torque correction for an electric machine comprising the steps of:
s1: presetting a plurality of rotating speed sampling points on a motor, acquiring motor parameters of each sampling point, calculating a flux linkage through a flux linkage calculation formula according to the motor parameters, and calibrating the dynamic flux linkage;
s2: when the motor is in a preset working condition, different alternating-direct axis current input combinations are given to obtain an estimated torque value, and the estimated torque value is obtained through a formulaRespectively calculating the inductance difference of the quadrature-direct axis and calibrating the inductance difference of the quadrature-direct axis; in which Te is electricityThe motor torque, pn is the number of pole pairs of the motor,for the synthetic flux linkage, iq is the Q-axis current, id is the D-axis current, lq is the Q-axis inductance, and Ld is the D-axis inductance.
S3: calibrating an estimated torque compensation coefficient;
s4: and outputting three calibration data tables for correcting the estimated torque in the motor control software, and finally outputting the optimized estimated torque.
Preferably, step S1 specifically includes the steps of:
s11, the controller is connected with low voltage and is in a free rotation state in the dragging process of the motor;
s12, dividing the rotating speed of the motor into ten points equally according to the highest rotating speed of the motor;
s13, dragging the motor to rotate to an evenly-distributed target rotating speed point by the dynamometer in the positive direction of the motor, and recording the line voltage displayed on the power analyzer at the moment;
and S14, recording the line voltage at each target rotating speed point according to the step S13, finally obtaining a three-dimensional table with the synthetic flux linkage and the horizontal and vertical coordinate axes as the temperature and the rotating speed, substituting the temperature and the rotating speed information into a flux linkage calculation formula, calculating to obtain a corresponding flux linkage value, and filling the flux linkage data obtained by calculation into a calibration table.
Preferably, step S2 specifically includes the steps of:
s21: the controller is connected with low voltage and high voltage, and the dynamometer drives the motor to rotate in the positive direction of the motor (the rotating speed of the motor is thirty-percent peak rotating speed);
s22: respectively filling the quadrature-direct axis current values corresponding to the current distribution calibration into calibration tool software;
s23: setting the calibration tool software in a quadrature-direct axis current distribution mode, and giving a target current;
s24: checking and recording a motor torque value displayed by the rack and a motor estimated torque value calculated in motor control software; s25: and calculating the quadrature-direct axis inductance difference through a quadrature-direct axis inductance difference formula and filling the quadrature-direct axis inductance difference into a quadrature-direct axis inductance difference calibration table.
Preferably, step S3 specifically includes the steps of:
s31: setting all data in an estimated torque compensation coefficient table in calibration tool software to be 1;
s32: the dynamometer drags the motor to rotate in the positive direction of the motor;
s33, setting the motor working mode as current given in the calibration tool software;
s34, setting different target currents, checking and recording a motor torque value displayed by the rack and a motor estimated torque value calculated in motor control software;
s35: and (4) summing the rack torque value recorded in the step (S34) and the idle load at the rotating speed to obtain the actual output torque of the motor, calculating by using an estimated torque compensation coefficient calculation formula to obtain an estimated torque compensation coefficient, and filling the estimated torque compensation coefficient into an estimated torque coefficient table.
Preferably, the estimated torque compensation coefficient calculation formula in step S3 is:
Factor_Compensation=Trq_TestRig/Trq_Cal
wherein, factor _ Compensation is an estimated torque Compensation coefficient, trq _ TestRig is an actual torque of the motor, and Trq _ Cal is an estimated torque of the motor.
Preferably, the flux linkage calculation formula in step S1 is:
in the formula (I), the compound is shown in the specification,for synthesizing the magnetic linkage, kt is a temperature coefficient, pn is a motor pole pair number, uab is a motor line voltage, and Nspeed is a motor rotating speed.
The beneficial effects of the invention are: according to an original motor electromagnetic torque formula, the quadrature-direct axis inductance is constant, and the torque estimation under different input conditions cannot be well coped with.
Drawings
FIG. 1 is a flow chart of a method for estimating torque of an electric machine according to an embodiment of the present invention.
Detailed Description
Firstly, the calculation of the difference value of the non-constant inductance involves the influence of input variables such as the temperature and the rotating speed of the motor. Under the premise that the resistance of the stator is influenced by temperature and the influence of the rotating speed on the flux linkage and the inductance, the method for calibrating the difference of the alternating-direct axis inductance is provided because the alternating-direct axis inductance under different input conditions (including different currents, temperatures, rotating speeds and the like) is complicated in theoretical calculation. The reverse process from the torque calculation formula is as follows: according to an original motor electromagnetic torque formula:in the formula, te is motor torque, pn is the number of pole pairs of the motor,for synthesizing magnetic flux linkage, iq is Q-axis current, id is D-axis current, lq is Q-axis inductance, and Ld is D-axis inductance, the original formula can be converted into:in the formula, the inductance difference of the alternating-direct axis can be considered to be only influenced by the alternating-direct axis current under the conditions of the current motor state, the rotating speed and the temperature. Obtaining different actual torque values according to different quadrature-direct axis current input combinations, respectively calculating quadrature-direct axis inductance differences through the formulas, and fitting to obtain a three-dimensional table of the quadrature-direct axis inductance differences and the currents; the influence of the rotating speed and the temperature on the synthetic magnetic chain phi f is preferably considered; the part comprises the influence of the temperature on the stator resistance, the line voltage under the current condition can be respectively measured at different rotating speeds and temperatures, and a three-dimensional table related to the flux linkage, the rotating speed and the temperature can be fitted according to the following formula;in the formula (I), the compound is shown in the specification,in order to synthesize a magnetic flux linkage, kt is a temperature coefficient, pn is a pole pair number of a motor, uab is a motor line voltage, and nsspeed is a motor rotational speed, another method for compensating an actually estimated torque coefficient mentioned above is to recalibrate an estimated torque by correcting a ratio of the estimated torque to a measured torque of a rack, and a theoretical formula is as follows: in the formula of Factor _ Compensation = Trq _ TestRig/Trq _ Cal, factor _ Compensation is an estimated torque Compensation coefficient, trq _ TestRig is the actual torque of the motor, and Trq _ Cal is the estimated torque of the motor. Preferably, other input conditions such as rotating speed, temperature and the like can be added to obtain the multidimensional compensation coefficient value. And (4) integrating the three tables obtained by the 2 parts, and using the three tables for correcting the estimated torque in the motor control software to finally output the optimized estimated torque. The method for improving the torque estimation precision of the permanent magnet synchronous motor is realized by calibrating the quadrature-direct axis inductance difference Ld-Lq and the actual estimated torque compensation coefficient.
The specific embodiment is as follows: the method for correcting the estimated torque of the motor, as shown in FIG. 1, comprises the following steps:
s1: calibrating a dynamic magnetic linkage; the method specifically comprises the following steps: the controller is connected with low voltage (high voltage is disconnected), and the motor is ensured to be always in a free rotation state in the dragging process; dividing the rotating speed of the motor into ten sampling points according to the highest rotating speed of the motor; the dynamometer drags a motor in the positive direction of the motor, when the rotating speed of the motor rotates to ten evenly-divided target rotating speed points, line voltage displayed on a power analyzer at the moment is recorded in sequence, a three-dimensional table with a synthetic flux and a horizontal and vertical axis as temperature and rotating speed is finally obtained, a corresponding flux value is obtained through a flux calculation formula after substituting relevant temperature and rotating speed information, flux data obtained through calculation is filled into a calibration table, and the flux calculation formula is as follows:
in the formula (I), the compound is shown in the specification,and finally, filling the dynamic flux linkage data obtained by calculation into a calibration table.
S2: calibrating the quadrature-direct axis inductance difference; the method specifically comprises the following steps: the controller is connected with low voltage and high voltage, and the dynamometer drives the motor to rotate in the positive direction of the motor (the rotating speed of the motor is thirty percent of the peak rotating speed); filling the corresponding quadrature-direct axis current values Id and Iq in the current distribution calibration into calibration tool software respectively; setting the calibration tool software in a quadrature-direct axis current distribution mode, giving a target current, and checking and recording a motor torque value displayed by the rack and a motor estimated torque value calculated in the motor control software; the quadrature-direct axis inductance difference is obtained through the quadrature-direct axis inductance difference formula calculation and is filled in a quadrature-direct axis inductance difference calibration table, and the formula is as follows:
the quadrature-direct axis inductance difference formula is as follows:is based on the electromagnetic torque formula of the original motorObtained by conversion, the inductance difference of the alternating-direct axis in the formula can be only influenced by alternating-direct axis current under the conditions of the current motor state, the rotating speed and the temperature, te is motor torque, pn is the number of pole pairs of the motor,for the synthetic flux linkage, iq is the Q-axis current, id is the D-axis current, lqIs a Q-axis inductor, and Ld is a D-axis inductor.
S3: calibrating the estimated torque compensation coefficient, and re-calibrating the estimated torque by a method of correcting the proportion of the estimated torque to the measured torque of the rack; the method specifically comprises the following steps: the method comprises the steps of ensuring that all data in an estimated torque compensation coefficient table in calibration tool software are set to be 1, enabling a dynamometer to drag a motor to rotate in the positive direction of the motor (the rotating speed of the motor is thirty percent of the peak rotating speed), setting the working mode of the motor to be current setting in the calibration tool software, setting different target currents, checking and recording a motor torque value displayed on a rack and a motor estimated torque value calculated in motor control software, summing the recorded rack torque value and no-load operation at the rotating speed to obtain the actual output torque of the motor, calculating an estimated torque compensation coefficient through an estimated torque compensation coefficient calculation formula, and filling the estimated torque compensation coefficient into the estimated torque coefficient table. The formula is as follows:
Factor_Compensation=Trq_TestRig/Trq_Cal
wherein, factor _ Compensation is an estimated torque Compensation coefficient, trq _ TestRig is an actual torque of the motor, and Trq _ Cal is an estimated torque of the motor.
S4: and outputting three calibration data tables for correcting the estimated torque in the motor control software, and finally outputting the optimized estimated torque.
The above-described embodiment is a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (6)
1. A method of correcting estimated torque of an electric machine, comprising the steps of:
s1: presetting a plurality of rotating speed sampling points on a motor, acquiring motor parameters of each sampling point, calculating a flux linkage through a flux linkage calculation formula according to the motor parameters, and calibrating the dynamic flux linkage;
s2: when the motor is in a preset working condition, different input combinations of the alternating current and the direct current are given to obtain an estimated torque value, and the estimated torque value is obtained through a formulaRespectively calculating quadrature-direct axis inductance difference, and calibrating the quadrature-direct axis inductance difference; in the formula, te is motor torque, pn is the number of pole pairs of the motor,for synthesizing a magnetic linkage, iq is Q-axis current, id is D-axis current, lq is Q-axis inductance, and Ld is D-axis inductance;
s3: calibrating an estimated torque compensation coefficient;
s4: and outputting three calibration data tables for correcting the estimated torque in the motor control software, and finally outputting the optimized estimated torque.
2. The method of estimating torque correction for an electric machine of claim 1,
the step S1 specifically includes the following steps:
s11, the controller is connected with low voltage and is in a free rotation state in the dragging process of the motor;
s12, dividing the rotating speed of the motor into ten points equally according to the highest rotating speed of the motor;
s13, dragging the motor to rotate to an evenly-distributed target rotating speed point by the dynamometer in the positive direction of the motor, and recording the line voltage displayed on the power analyzer at the moment;
and S14, recording the line voltage at each target rotating speed point according to the step S13, finally obtaining a three-dimensional table with the synthetic flux linkage and the horizontal and vertical coordinate axes as the temperature and the rotating speed, substituting the temperature and the rotating speed information into a flux linkage calculation formula, calculating to obtain a corresponding flux linkage value, and filling the flux linkage data obtained by calculation into a calibration table.
3. The method of estimated torque correction of an electric machine according to claim 1 or 2,
the step S2 specifically includes the following steps:
s21: the controller is connected with low voltage and high voltage, and the dynamometer drives the motor to rotate in the positive direction of the motor;
s22: respectively filling the quadrature-direct axis current values corresponding to the current distribution calibration into calibration tool software;
s23: placing the calibration tool software in a quadrature-direct axis current distribution mode, and setting a target current;
s24: checking and recording a motor torque value displayed by the rack and a motor estimated torque value calculated in motor control software;
s25: and calculating by a quadrature-direct axis inductance difference formula to obtain a quadrature-direct axis inductance difference and filling the quadrature-direct axis inductance difference into a quadrature-direct axis inductance difference calibration table.
4. The method of estimating torque correction for an electric machine of claim 3,
the step S3 specifically includes the following steps:
s31: setting all data in an estimated torque compensation coefficient table in calibration tool software to be 1;
s32: the dynamometer drags the motor to rotate in the positive direction of the motor;
s33, setting the motor working mode as current given in the calibration tool software;
s34, setting different target currents, checking and recording a motor torque value displayed by the rack and a motor estimated torque value calculated in motor control software;
s35: and (4) performing summation on the rack torque value recorded in the step (S34) and the idle load at the rotating speed to obtain the actual output torque of the motor, calculating an estimated torque compensation coefficient through an estimated torque compensation coefficient calculation formula, and filling the estimated torque compensation coefficient into an estimated torque coefficient table.
5. The method of estimating torque correction for an electric machine of claim 4, wherein said estimated torque compensation factor is calculated as:
Factor_Compensation=Trq_TestRig/Trq_Cal
wherein, factor _ Compensation is an estimated torque Compensation coefficient, trq _ TestRig is an actual torque of the motor, and Trq _ Cal is an estimated torque of the motor.
6. The method of estimating torque correction for an electric machine of claim 1, wherein said flux linkage calculation formula is:
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CN115476701A (en) * | 2022-10-17 | 2022-12-16 | 潍柴动力股份有限公司 | Motor torque determination method and device |
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CN115476701A (en) * | 2022-10-17 | 2022-12-16 | 潍柴动力股份有限公司 | Motor torque determination method and device |
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