CN108809185B - Method and system for controlling motor torque of electric automobile - Google Patents

Abstract

The invention provides a method and a system for controlling motor torque of an electric automobile, wherein the method comprises the following steps: obtaining I controlling motor torque output_d/I_qTable; according to the formula I_d/I_qThe meter calibrates the torque output by the motorTo obtain the required torque calibration value T of multiple groups of corresponding motors_{Need to}And executing a torque calibration value T_HandleAnd calibrating a formula according to the torque precision: t is_Handle＝aT_{Need to} ²+bT_{Need to}+ c, calculating to obtain the values of equation coefficients a, b and c; obtaining the corrected output torque of the motor according to the torque precision calibration formula and the actual required torque of the motor, and passing through the I_d/I_qObtaining a corrected I corresponding to the corrected output torque_dAnd I_q(ii) a Subjecting the said I_dAnd I_qAnd PI closed loop control parameters used as the output torque of the motor are used for correcting the output torque of the motor. The invention can improve the precision of the output torque of the motor and improve the comfort and the safety of the electric automobile.

Description

Method and system for controlling motor torque of electric automobile

Technical Field

The invention relates to a motor control technology, in particular to a method and a system for controlling motor torque of an electric automobile.

Background

The driving system is one of three main core parts of the electric automobile, and the performance of the driving system directly determines the performance of the whole automobile. The torque output of the motor is an important index for evaluating the performance of the electric drive system, wherein the index for evaluating the torque output not only has the condition that whether peak torque can be output, but also needs to carry out examination and evaluation on the precision of the torque output; when the vehicle starts, the vehicle controller performs closed-loop control on the output torque of the motor, the torque output is inaccurate, and the vehicle shakes, so that the requirement on the precision of the output torque of the motor is high; when the vehicle is accelerated, the motor is required to output peak torque, and if the peak torque cannot be reached, the power performance of the whole vehicle is seriously influenced.

The current torque output precision is generally achieved by motor suppliers that the torque precision is as follows: 100Nm or less, i.e.,. + -.5 Nm or more, 100Nm or more, i.e.,. + -.5% or less. The torque control mode of each motor supplier is basically the same, but the torque output precision can meet the requirements at different voltages and different rotating speed sections, which is difficult. Meanwhile, when the electric automobile runs at a low speed, corresponding voltages of the batteries are different when the batteries are at different SOC, and the output performance of the motor is different when the motors are at different voltages, so that if no uniform torque precision control under different conditions exists, the vehicle controller is difficult to control the vehicle, and the consistency of the vehicle is ensured; therefore, how to ensure that the torque output precision of the electric drive system meets the development target requirement under different voltages has important research significance.

Disclosure of Invention

The invention provides a method and a system for controlling motor torque of an electric automobile, which solve the problem that the existing electric automobile is easy to shake due to inaccurate motor torque output when running at low speed, can improve the precision of the motor output torque, and improve the comfort and the safety of the use of the electric automobile.

In order to achieve the above purpose, the invention provides the following technical scheme:

a method of motor torque control for an electric vehicle, comprising:

obtaining I controlling motor torque output_d/I_qTable;

according to the formula I_d/I_qThe meter calibrates the torque output by the motor to obtain multiple sets of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleAnd calibrating a formula according to the torque precision: t is_Handle＝aT_{Need to} ²+bT_{Need to}+ c, calculating to obtain the values of equation coefficients a, b and c;

obtaining the corrected output torque of the motor according to the torque precision calibration formula and the actual required torque of the motor, and passing through the I_d/I_qObtaining a corrected I corresponding to the corrected output torque_dAnd I_q；

Subjecting the said I_dAnd I_qAnd PI closed loop control parameters used as the output torque of the motor are used for correcting the output torque of the motor.

Preferably, the method further comprises the following steps:

obtaining three-phase stator current input into a motor, and performing clark transformation on the three-phase stator current to obtain current components under a static coordinate system;

obtaining a d-axis current component I 'in a rotating coordinate system by carrying out park transformation on the current component'_dAnd q-axis current component I'_q；

Is prepared from'_dAnd said I_dL of'_qAnd said I_qAnd comparing, and taking the difference value as the input of the PI closed-loop control.

Preferably, the method further comprises the following steps:

acquiring a rotor position signal of the motor, and calculating according to the rotor position signal to obtain an output angular speed of the motor;

and calculating to obtain a feedback rotating speed value of the motor according to the angular speed, and using the feedback rotating speed value as a PI closed-loop control parameter of the output torque of the motor.

Preferably, the obtaining of I for controlling the torque output of the motor_d/I_qThe table includes:

obtaining stator currents corresponding to motor torques at different rotating speeds according to magnetic circuit simulation of the motor;

converting the stator current through park to obtain corresponding d-axis current and q-axis current;

summarizing the d-axis current, the q-axis current and the motor torque according to a maximum torque current ratio principle to form the I_d/I_qTable (7).

Preferably, said is according to said I_d/I_qThe meter calibrates the torque output by the motor to obtain multiple sets of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleThe method comprises the following steps:

setting a rotating speed step length and a torque step length of an initial test of the motor;

acquiring the required torque calibration value and the execution torque calibration value of the motor at different rotating speeds according to the rotating speed step length;

and acquiring the execution torque calibration value corresponding to the required torque calibration value of the motor under different working voltages according to the torque step length.

Preferably, the compound I_dAnd I_qThe PI closed-loop control parameter used as the output torque of the motor to correct the output torque of the motor comprises the following steps:

is prepared from'_dAnd said I_dL of'_qAnd said I_qComparing, taking the difference value as the input of a PI regulator, and performing park inverse transformation on the output voltage of the PI regulator to obtain a voltage component of a static coordinate system;

and modulating the voltage component through pulse width to obtain a three-phase PWM wave, and controlling the output of the motor torque according to the three-phase PWM wave.

The present invention also provides a system for controlling motor torque of an electric vehicle, comprising:

an acquisition unit for acquiring I for controlling torque output of the motor_d/I_qTable;

a calibration unit for calibrating the calibration unit according to the I_d/I_qThe meter calibrates the torque output by the motor to obtain multiple sets of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleAnd calibrating a formula according to the torque precision: t is_Handle＝aT_{Need to} ²+bT_{Need to}+ c, calculating to obtain the values of equation coefficients a, b and c;

a torque correction unit for obtaining the corrected output torque of the motor according to the torque precision calibration formula and the actual required torque of the motor, and passing the corrected output torque through the I_d/I_qObtaining a corrected I corresponding to the corrected output torque_dAnd I_q；

A torque control unit for controlling the torque I_dAnd I_qAnd PI closed loop control parameters used as the output torque of the motor are used for correcting the output torque of the motor.

Preferably, the method further comprises the following steps:

the current conversion unit is used for acquiring three-phase stator current input into the motor and performing clark transformation on the three-phase stator current to obtain current components under a static coordinate system;

the current conversion unit is further used for obtaining a d-axis current component I 'in a rotating coordinate system by carrying out park conversion on the current component'_dAnd q-axis current component I'_q；

A current comparison unit for comparing the I'_dAnd said I_dL of'_qAnd said I_qAnd comparing, and taking the difference value as the input of the PI closed-loop control.

Preferably, the method further comprises the following steps:

the rotating speed feedback unit is used for acquiring a rotor position signal of the motor and calculating to obtain the output angular speed of the motor according to the rotor position signal;

the rotating speed feedback unit is also used for calculating a feedback rotating speed value of the motor according to the angular speed and using the feedback rotating speed value as a PI closed-loop control parameter of the output torque of the motor.

Preferably, the torque control unit includes: the device comprises a PI regulator, a coordinate converter and a pulse width modulation module;

is prepared from'_dAnd said I_dL of'_qAnd said I_qComparing, using the difference value as the input of the PI regulator, and performing park inverse transformation on the output voltage of the PI regulator through the coordinate converter to obtain the voltage component of a static coordinate system;

and the pulse width modulation module is used for carrying out pulse width modulation on the voltage component to obtain a three-phase PWM wave and controlling the output of the motor torque according to the three-phase PWM wave.

The invention provides a method and a system for controlling motor torque of an electric automobile, wherein the method is according to I_d/I_qThe meter calibrates the torque output by the motor to obtain a corrected I_dAnd I_qAnd the output torque of the motor is used as a PI closed-loop control parameter of the output torque of the motor so as to realize the correction of the output torque of the motor. The problem of current electric automobile when the low-speed operation because motor torque output is inaccurate easily take place the phenomenon of shake is solved, can improve motor output torque precision, improve the travelling comfort and the security that electric automobile used.

Drawings

In order to more clearly describe the specific embodiments of the present invention, the drawings to be used in the embodiments will be briefly described below.

FIG. 1: the invention provides a method flow chart for controlling the motor torque of an electric automobile;

FIG. 2: the embodiment of the invention provides a motor torque control structure schematic diagram.

Detailed Description

In order to make the technical field of the invention better understand the scheme of the embodiment of the invention, the embodiment of the invention is further described in detail with reference to the drawings and the implementation mode.

Aiming at the problems that the precision of the motor control output torque of the current electric automobile is not high and the current electric automobile is easy to shake, the invention provides a method and a system for controlling the motor torque of the electric automobile, according to I_d/I_qThe meter calibrates the torque output by the motor to obtain a corrected I_dAnd I_qAnd the output torque of the motor is used as a PI closed-loop control parameter of the output torque of the motor so as to realize the correction of the output torque of the motor. The problem of current electric automobile when low-speed operation because motor torque output is inaccurate easily take place the phenomenon of shake is solved, can improve motor output torque precision, improve the travelling comfort and the security that electric automobile used.

As shown in fig. 1, the present invention provides a method for controlling motor torque of an electric vehicle, comprising the steps of:

s1: obtaining I controlling motor torque output_d/I_qTable;

s2: according to the formula I_d/I_qThe meter calibrates the torque output by the motor to obtain multiple sets of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleAnd calibrating a formula according to the torque precision: t is_Handle＝aT_{Need to} ²+bT_{Need to}+ c, calculating to obtain the values of equation coefficients a, b and c;

s3: obtaining the motor according to the torque precision calibration formula and the actual required torque of the motorAnd passing said I_d/I_qObtaining a corrected I corresponding to the corrected output torque_dAnd I_q；

S4: subjecting the said I_dAnd I_qAnd PI closed loop control parameters used as the output torque of the motor are used for correcting the output torque of the motor.

Specifically, I from controlling motor torque output_d/I_qTable, corresponding relationships of torque, current and back emf are obtained from I_d/I_qObtaining the required torque corresponding to I on the table_dAnd I_qThe value is obtained. According to I_d/I_qThe table calibrates the torques output by the motor under different voltages to obtain a corresponding relation between the required torque and the actual execution torque, as shown in table 1. Since T is known_HandleAnd T_{Need to}The values of equation coefficients a, b and c of the torque precision calibration formula can be easily solved, the corrected output torque of the motor can be obtained according to the torque precision calibration formula and the actual required torque, and I is inquired_d/I_qTabulating a corrected I corresponding to the corrected output torque_dAnd I_q. Will I_dAnd I_qThe PI closed-loop control parameter is used for correcting the torque output by the motor, so that the accuracy of the torque output by the motor is improved, and the problem that the electric automobile is easy to shake when running at low speed can be solved.

Watch 1

Rotational speed	Required torque	Execution torque	Difference value	Rotational speed	Required torque	Execution torque	Difference value	Rotational speed	Required torque	Execution torque	Difference value
												1500	10	11.3	-1.3	2000	10	11.2	-1.2	2500	10	11	-1
1500	20	21.1	-1.1	2000	20	20.9	-0.9	2500	20	20.6	-0.6
												1500	30	30.7	-0.7	2000	30	30.3	-0.3	2500	30	29.9	0.1
1500	40	40.2	-0.2	2000	40	39.7	0.3	2500	40	39.2	0.8
												1500	50	49.9	0.1	2000	50	49.4	0.6	2500	50	48.8	1.2
1500	60	69.3	0.7	2000	60	58.8	1.2	2500	60	58	2
												1500	70	68.6	1.4	2000	70	68	2	2500	70	67.2	2.8
1500	80	78	2	2000	80	77.3	2.7	2500	80	76.6	3.4
												1500	160	155.7	4.3	2000	160	154.5	5.5	2500	160	153.3	6.7
1500	...	...	...	...	...	...	...	...	...	...	...
												1500	230	223.8	6.2	2000	230	221.9	8.1	2500	230	220.5	9.5
1500	240	233.5	6.5	2000	240	231.4	8.6	2500	240	230.1	9.9
												1500	250	243.2	6.8	2000	250	240.9	9.1	2500	250	239.6	10.4
1500	260	252.8	7.2	2000	260	250.5	9.5	2500	260	249	11
												1500	270	262	8	2000	270	259.8	10.2	2500	270	258.2	11.8

It should be noted that, when the torque output by the motor is calibrated, the test can be performed on the motor rack. In practical applications, the Id/Iq tables, a, b, and c are often embedded in motor control software to implement motor control. Meanwhile, the required torque calibration values T of multiple groups of corresponding motors_{Need to}And executing a torque calibration value T_HandleMultiple sets of data for a, b, and c can be calculated, and the optimal values can be obtained by fitting. The obtained data of a, b and c may be averaged to obtain an average value. The method can also be used for screening and judging a plurality of groups of data a, b and c, judging whether the values of a, b and c are qualified or not through torque retest, and if the values of a, b and c are not qualified, selecting the required torque calibration value T of the other group of corresponding motors_{Need to}And executing a torque calibration value T_HandleAnd re-calculating the values of a, b and c until the values are qualified. Of course, the values of a, b and c can be obtained by other mathematical methods and can be determined according to actual needs.

Further, the method also includes:

s5: obtaining three-phase stator current input into a motor, and performing clark transformation on the three-phase stator current to obtain current components under a static coordinate system;

s6: obtaining a d-axis current component I 'in a rotating coordinate system by carrying out park transformation on the current component'_dAnd q-axis current component I'_q；

S7: is prepared from'_dAnd said I_dL of'_qAnd said I_qAnd comparing, and taking the difference value as the input of the PI closed-loop control.

In practical application, three-phase stator current I is converted_a、I_b、I_cCurrent sub-power I obtained by performing clark conversion_αAnd I_βFurther processed by park conversion to give I'_dAnd l'_qPrepared from l'_dAnd I_dAnd l 'and'_qAnd I_qThe difference values of (a) and (b) are respectively used as the input of the PI closed-loop control.

Still further, the method further comprises:

s8: acquiring a rotor position signal of the motor, and calculating according to the rotor position signal to obtain an output angular speed of the motor;

s9: and calculating to obtain a feedback rotating speed value of the motor according to the angular speed, and using the feedback rotating speed value as a PI closed-loop control parameter of the output torque of the motor.

Obtaining torque output of control motor_d/I_qA table, comprising:

s11: obtaining stator currents corresponding to motor torques at different rotating speeds according to magnetic circuit simulation of the motor;

s12: converting the stator current through park to obtain corresponding d-axis current and q-axis current;

s13: summarizing the d-axis current, the q-axis current and the motor torque according to a maximum torque current ratio principle to form the I_d/I_qTable (7).

In practical application, based on reasonable design of the thickness of the silicon steel sheets of the stator and the rotor, the winding mode of the enameled wire, the arrangement form of the magnetic steel and the size of the air gap, the power, the torque and the rotating speed of the motor can meet the design through simulation calculation of motor magnetic circuit simulation software Ansoft under the specified current (the maximum current allowed by the IGBT) and voltage (battery voltage), and the magnetic circuit scheme is confirmed. Based on the magnetic circuit scheme, I corresponding to motor torque at different rotating speeds is output_d/I_qTable; i is_d，I_qSelecting a principle, namely a maximum torque current ratio principle before a rated rotating speed; after the rated rotation speed, setting the step length to be 150r/min, and determining and summarizing into a table according to the principle of the maximum torque current ratio within the range that the back electromotive force of the motor is less than or equal to the battery voltage so as to be used for controlling the motor.

Said according to said I_d/I_qThe meter calibrates the torque output by the motor to obtain multiple sets of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleThe method comprises the following steps:

s21: setting a rotating speed step length and a torque step length of an initial test of the motor;

s22: acquiring the required torque calibration value and the execution torque calibration value of the motor at different rotating speeds according to the rotating speed step length;

s23: and acquiring the execution torque calibration value corresponding to the required torque calibration value of the motor under different working voltages according to the torque step length.

It should be noted that the rotating speed step length and the torque step length of the motor during the initial test are set according to the requirements of the whole vehicle on the torque precision of the motor in different rotating speed sections and the characteristics of the deviation between the executing torque and the required torque of the motor.

The said I_dAnd I_qThe PI closed-loop control parameter used as the output torque of the motor to correct the output torque of the motor comprises the following steps:

s41: is prepared from'_dAnd said I_dL of'_qAnd said I_qComparing, using the difference as the input of PI regulator, and regulating the PIThe output voltage of the node device is subjected to park inverse transformation to obtain a voltage component of a static coordinate system;

s42: and modulating the voltage component through pulse width to obtain a three-phase PWM wave, and controlling the output of the motor torque according to the three-phase PWM wave.

In practical application, the detected three-phase stator currents ia, ib and ic of the permanent magnet synchronous motor are subjected to click conversion through a current sensor to obtain a current component I under a static coordinate system_αAnd I_β(ii) a When the park is converted, the calculated electric angle theta e of the motor is equal to P multiplied by theta m (wherein P is the pole pair number of the motor, and theta m is the mechanical angle of the output of the motor) and the current component I under the two-phase static coordinate system obtained by clark conversion_αAnd I_βThen, a stationary-rotary conversion is performed to obtain a current value i in a two-phase synchronous rotating coordinate system_dAnd i_q(ii) a Is prepared from'_dAnd I_dAnd l 'and'_qAnd I_qThe difference values are respectively used as the input of a PI regulator, and the output voltages U of the d-axis current loop PI regulator and the q-axis current loop PI regulator can be respectively obtained through the calculation of the d-axis current PI regulator and the q-axis current PI regulator_d，U_q(ii) a Then the obtained output voltage U_d，U_qAnd the electric angle value theta e of the motor is subjected to park inverse transformation to obtain U_α，U_βWill U is_α、U_βThe three-phase PWM waveform is input to the pulse width modulation module to calculate the duty ratio of three phases, the three-phase PWM waveform responding to the inverter is output, and the inverter outputs three-phase voltage to drive the permanent magnet synchronous motor to operate.

It can be seen that the present invention provides a method for motor torque control of an electric vehicle according to I_d/I_qThe meter calibrates the torque output by the motor to obtain a corrected I_dAnd I_qAnd the output torque of the motor is used as a PI closed-loop control parameter of the output torque of the motor so as to realize the correction of the output torque of the motor. The problem of current electric automobile when the low-speed operation because motor torque output is inaccurate easily take place the phenomenon of shake is solved, can improve motor output torque precision, improve the travelling comfort and the security that electric automobile used.

The invention also provides a system for controlling the motor torque of the electric automobileA system, comprising: an acquisition unit for acquiring I for controlling torque output of the motor_d/I_qTable (7). A calibration unit for calibrating the calibration unit according to the I_d/I_qThe meter calibrates the torque output by the motor to obtain multiple sets of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleAnd calibrating a formula according to the torque precision: t is_Handle＝aT_{Need to} ²+bT_{Need to}And + c, calculating to obtain the values of the equation coefficients a, b and c. A torque correction unit for obtaining the corrected output torque of the motor according to the torque precision calibration formula and the actual required torque of the motor, and passing the corrected output torque through the I_d/I_qObtaining a corrected I corresponding to the corrected output torque_dAnd I_q. A torque control unit for controlling the torque I_dAnd I_qAnd PI closed loop control parameters used as the output torque of the motor are used for correcting the output torque of the motor.

Further, the system further comprises: and the current conversion unit is used for acquiring three-phase stator current input into the motor and performing clark transformation on the three-phase stator current to obtain a current component under a static coordinate system. The current conversion unit is further used for obtaining a d-axis current component I 'in a rotating coordinate system by carrying out park conversion on the current component'_dAnd q-axis current component I'_q. A current comparison unit for comparing the I'_dAnd said Id, said I'_qAnd said I_qAnd comparing, and taking the difference value as the input of the PI closed-loop control.

Still further, the system further comprises: and the rotating speed feedback unit is used for acquiring a rotor position signal of the motor and calculating to obtain the output angular speed of the motor according to the rotor position signal. The rotating speed feedback unit is also used for calculating a feedback rotating speed value of the motor according to the angular speed and using the feedback rotating speed value as a PI closed-loop control parameter of the output torque of the motor.

As shown in fig. 2, the torque control unit includes: the device comprises a PI regulator, a coordinate converter and a pulse width modulation module. Will be the I'_dAnd said I_dL of'_qAnd said I_qThe comparison is carried out in such a way that,and taking the difference value as the input of the PI regulator, and performing park inverse transformation on the output voltage of the PI regulator through the coordinate converter to obtain the voltage component of the static coordinate system. And the pulse width modulation module is used for carrying out pulse width modulation on the voltage component to obtain a three-phase PWM wave and controlling the output of the motor torque according to the three-phase PWM wave.

Therefore, the invention provides a system for controlling the motor torque of an electric automobile, which is based on I through a calibration unit_d/I_qThe torque output by the motor is calibrated by the meter, the torque correction unit obtains the corrected output torque according to the torque precision calibration formula and the actual required torque of the motor, and the corrected output torque is obtained according to I_d/I_qTable acquisition of corrected I_dAnd I_qAnd further, the torque output of the motor is controlled by the torque control unit. The problem of current electric automobile when the low-speed operation because motor torque output is inaccurate easily take place the phenomenon of shake is solved, can improve motor output torque precision, improve the travelling comfort and the security that electric automobile used.

The construction, features and functions of the present invention have been described in detail with reference to the embodiments shown in the drawings, but the present invention is not limited to the embodiments shown in the drawings, and all equivalent embodiments modified or modified by the spirit and scope of the present invention should be protected without departing from the spirit of the present invention.

Claims (10)

1. A method of motor torque control for an electric vehicle, comprising:

obtaining I controlling motor torque output_d/I_qTable;

according to the formula I_d/I_qThe meter calibrates the torque output by the motor to obtain multiple sets of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleAnd calibrating a formula according to the torque precision: t is_Handle＝aT_{Need to} ²+bT_{Need to}+ c, calculating to obtain the values of equation coefficients a, b and c;

obtaining the corrected output torque of the motor according to the torque precision calibration formula and the actual required torque of the motor, and passing through the I_d/I_qObtaining a corrected I corresponding to the corrected output torque_dAnd I_q；

Subjecting the said I_dAnd I_qAnd PI closed loop control parameters used as the output torque of the motor are used for correcting the output torque of the motor.

2. The method of motor torque control of an electric vehicle according to claim 1, further comprising:

obtaining three-phase stator current input into a motor, and performing clark transformation on the three-phase stator current to obtain current components under a static coordinate system;

obtaining a d-axis current component I 'in a rotating coordinate system by carrying out park transformation on the current component'_dAnd q-axis current component I'_q；

Is prepared from'_dAnd said I_dL of'_qAnd said I_qAnd comparing, and taking the difference value as the input of the PI closed-loop control.

3. The method of motor torque control of an electric vehicle according to claim 2, further comprising:

acquiring a rotor position signal of the motor, and calculating according to the rotor position signal to obtain an output angular speed of the motor;

and calculating to obtain a feedback rotating speed value of the motor according to the angular speed, and using the feedback rotating speed value as a PI closed-loop control parameter of the output torque of the motor.

4. The method of motor torque control of an electric vehicle according to claim 3, wherein said obtaining I controlling motor torque output_d/I_qThe table includes:

obtaining stator currents corresponding to motor torques at different rotating speeds according to magnetic circuit simulation of the motor;

converting the stator current through park to obtain corresponding d-axis current and q-axis current;

summarizing the d-axis current, the q-axis current and the motor torque according to a maximum torque current ratio principle to form the I_d/I_qTable (7).

5. The method of claim 4, wherein the I is a function of the motor torque control of the electric vehicle_d/I_qThe meter calibrates the torque output by the motor to obtain multiple sets of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleThe method comprises the following steps:

setting a rotating speed step length and a torque step length of an initial test of the motor;

acquiring the required torque calibration value and the execution torque calibration value of the motor at different rotating speeds according to the rotating speed step length;

and acquiring the execution torque calibration value corresponding to the required torque calibration value of the motor under different working voltages according to the torque step length.

6. The method of claim 5, wherein the I is controlled by a motor torque control method of an electric vehicle_dAnd I_qThe PI closed-loop control parameter used as the output torque of the motor to correct the output torque of the motor comprises the following steps:

is prepared from'_dAnd said I_dL of'_qAnd said I_qComparing, taking the difference value as the input of a PI regulator, and performing park inverse transformation on the output voltage of the PI regulator to obtain a voltage component of a static coordinate system;

and modulating the voltage component through pulse width to obtain a three-phase PWM wave, and controlling the output of the motor torque according to the three-phase PWM wave.

7. A system for motor torque control of an electric vehicle, comprising:

an acquisition unit for acquiring I for controlling torque output of the motor_d/I_qTable;

a calibration unit used for calibrating the torque output by the motor according to the Id/Iq table so as to obtain a plurality of groups of corresponding required torque calibration values T of the motor_{Need to}And executing a torque calibration value T_HandleAnd calibrating a formula according to the torque precision: t is_Handle＝aT_{Need to} ²+bT_{Need to}+ c, calculating to obtain the values of equation coefficients a, b and c;

a torque correction unit for obtaining the corrected output torque of the motor according to the torque precision calibration formula and the actual required torque of the motor, and passing the corrected output torque through the I_d/I_qObtaining a corrected I corresponding to the corrected output torque_dAnd I_q；

A torque control unit for controlling the torque I_dAnd I_qAnd PI closed loop control parameters used as the output torque of the motor are used for correcting the output torque of the motor.

8. The system of motor torque control of an electric vehicle of claim 7, further comprising:

the current conversion unit is used for acquiring three-phase stator current input into the motor and performing clark transformation on the three-phase stator current to obtain current components under a static coordinate system;

the current conversion unit is further used for obtaining a d-axis current component I 'in a rotating coordinate system by carrying out park conversion on the current component'_dAnd q-axis current component I'_q；

A current comparison unit for comparing the I'_dAnd said I_dL of'_qAnd said I_qAnd comparing, and taking the difference value as the input of the PI closed-loop control.

9. The system of motor torque control of an electric vehicle of claim 8, further comprising:

the rotating speed feedback unit is used for acquiring a rotor position signal of the motor and calculating to obtain the output angular speed of the motor according to the rotor position signal;

the rotating speed feedback unit is also used for calculating a feedback rotating speed value of the motor according to the angular speed and using the feedback rotating speed value as a PI closed-loop control parameter of the output torque of the motor.

10. The system of motor torque control of an electric vehicle according to claim 9, wherein the torque control unit includes: the device comprises a PI regulator, a coordinate converter and a pulse width modulation module;

is prepared from'_dAnd said I_dL of'_qAnd said I_qComparing, using the difference value as the input of the PI regulator, and performing park inverse transformation on the output voltage of the PI regulator through the coordinate converter to obtain the voltage component of a static coordinate system;

and the pulse width modulation module is used for carrying out pulse width modulation on the voltage component to obtain a three-phase PWM wave and controlling the output of the motor torque according to the three-phase PWM wave.

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