阅读说明：本技术 三相异步电机输出转矩控制方法及控制装置 (Control method and control device for output torque of three-phase asynchronous motor ) 是由 赵许强 胡冰 崔晓光 咸粤飞 于 2019-10-31 设计创作，主要内容包括：本发明提供的一种三相异步电机输出转矩控制方法及控制装置,包括：在不同电机温度给定值下,建立不同输出转矩给定值、不同励磁电流给定值与转矩电流给定值的查询表；测量电机温度值以及获取输出转矩给定值和励磁电流给定值；根据电机温度值、输出转矩给定值、励磁电流给定值,利用查询表查询转矩电流给定值；根据转矩电流给定值,控制转矩电流值等于转矩电流给定值,控制励磁电流值等于励磁电流给定值,实现输出转矩的控制。该方法减少了闭环控制输出转矩的成本投入；考虑励磁电流和电机温度对输出转矩控制的影响,减少了输出转矩给定值和实际输出转矩值的误差,避免了传统查表法只考虑不同转速对输出转矩控制的影响造成的转矩控制精度低的弊端。(The invention provides a control method and a control device for output torque of a three-phase asynchronous motor, which comprises the following steps: under different motor temperature given values, establishing a lookup table of different output torque given values, different exciting current given values and torque current given values; measuring a motor temperature value and acquiring an output torque given value and an exciting current given value; according to the motor temperature value, the output torque given value and the exciting current given value, inquiring the torque current given value by using a lookup table; and controlling the torque current value to be equal to the torque current given value and the exciting current value to be equal to the exciting current given value according to the torque current given value, so as to realize the control of the output torque. The method reduces the cost investment of closed-loop control output torque; the influence of exciting current and motor temperature on output torque control is considered, the error of an output torque given value and an actual output torque value is reduced, and the defect of low torque control precision caused by the fact that only the influence of different rotating speeds on the output torque control is considered in the traditional table look-up method is avoided.)

1. A method for controlling output torque of a three-phase asynchronous motor is characterized by comprising the following steps:

under different motor temperature given values, establishing a lookup table of different output torque given values, different exciting current given values and torque current given values;

measuring a motor temperature value of the three-phase asynchronous motor in real time and acquiring an output torque given value and an exciting current given value in real time;

inquiring the set value of the torque current by utilizing an established inquiry table according to the real-time measured motor temperature value and the real-time acquired set value of the output torque and the set value of the exciting current;

and controlling the torque current value of the three-phase asynchronous motor to be equal to the given torque current value and the exciting current value of the three-phase asynchronous motor to be equal to the given exciting current value according to the inquired given torque current value, so as to realize the control of the output torque of the three-phase asynchronous motor.

2. The method according to claim 1, wherein the establishing of the lookup table for different output torque set values, different excitation current set values and torque current set values at different motor temperature set values specifically comprises:

s1: setting the temperature of the motor, the exciting current and the step length of the output torque; determining the value ranges of the motor temperature, the exciting current and the output torque according to the set step lengths of the motor temperature, the exciting current and the output torque;

s2: starting a three-phase asynchronous motor counter-dragging platform and a three-phase asynchronous motor controller, and setting a given rotating speed value of the three-phase asynchronous motor;

s3: setting a motor temperature given value in the value range of the determined motor temperature, and controlling the motor temperature to the motor temperature given value;

s4: after the temperature of the motor is stabilized at a given value of the motor temperature, setting a given value of the exciting current and a given value of the output torque within the value ranges of the determined exciting current and the output torque;

s5: adjusting the given value of the torque current to ensure that the actual output torque value of the three-phase asynchronous motor is equal to the given value of the output torque, and recording the given value of the torque current at the moment;

s6: and respectively modifying the given value of the output torque, the given value of the exciting current and the given value of the motor temperature within the determined value ranges of the output torque, the exciting current and the motor temperature, thereby obtaining a torque current given value query table corresponding to different given values of the exciting current and different given values of the output torque under different given values of the motor temperature.

3. The method according to claim 2, wherein the determination method of the value ranges of the motor temperature, the excitation current and the output torque specifically comprises the following steps:

determining the value range of the motor temperature, selecting a step length, starting from 30 ℃ according to the selected step length, taking 1 interval point every 1 step length, and generating a motor temperature sequence at least comprising 2 interval points;

determining the value range of the exciting current, selecting a step length, starting from 5A according to the selected step length, taking 1 interval point every 1 step length, and generating an exciting current sequence at least comprising 15 interval points;

determining the value range of the output torque, selecting the step length, starting from-50 Nm according to the selected step length, taking 1 interval point every 1 step length, and generating an excitation current sequence at least comprising 15 interval points.

4. The method according to claim 3, wherein obtaining a lookup table of torque current set values corresponding to different excitation current set values and different output torque set values under different motor temperature set values in S6 specifically comprises:

s601: in the value range of the determined output torque, modifying the given value of the output torque from-50 Nm according to the obtained interval points, and repeating the steps S4 and S5 until all the interval points in the output torque sequence are traversed to obtain the query data of the given value of the exciting current and the given value of the torque current corresponding to the given values of different output torques under the given value of the motor temperature;

s602: modifying the given value of the exciting current from 5A according to the obtained interval points within the determined value range of the exciting current, and repeating the steps S4, S5 and S601 until all interval points in the exciting current sequence are traversed to obtain query data of the given value of the torque current corresponding to different given values of the exciting current and different given values of the output torque under the given value of the temperature of the motor;

s603: within the value range of the determined motor temperature, modifying the given value of the motor temperature from 30 ℃ according to the taken interval points, and repeating the steps S3, S4, S5, S601 and S602 until all the interval points in the motor temperature sequence are traversed to obtain query data of the given values of the torque currents corresponding to different given values of the exciting currents and different given values of the output torques under different given values of the motor temperature;

s604: and establishing a two-dimensional array query table of the torque current given values corresponding to the different exciting current given values and the different output torque given values under the different motor temperature given values according to the obtained query data of the torque current given values corresponding to the different exciting current given values and the different output torque given values under the different motor temperature given values.

5. The method according to claim 4, wherein the step of inquiring the given torque and current values by using the established lookup table according to the motor temperature value measured in real time and the given output torque and exciting current values obtained in real time comprises the following steps:

and inquiring the set value of the torque current by using a linear interpolation method by utilizing the established two-dimensional array inquiry table according to the real-time measured motor temperature value and the real-time acquired set value of the output torque and the set value of the exciting current.

6. The method according to claim 5, wherein the method for measuring the motor temperature value in real time specifically comprises:

and measuring the motor temperature value of the three-phase asynchronous motor in real time by using a motor temperature sensor, and obtaining the processed motor temperature value after low-pass filtering the acquired motor temperature value.

7. An output torque control device of a three-phase asynchronous motor, comprising:

the query unit is used for establishing a query table of different output torque given values, different exciting current given values and torque current given values under different motor temperature given values;

the acquisition unit is used for measuring the motor temperature value of the three-phase asynchronous motor in real time;

the control unit is used for acquiring an output torque given value and an exciting current given value in real time; the device is used for inquiring the set value of the torque current by utilizing the established lookup table according to the real-time measured motor temperature value and the real-time acquired set value of the output torque and the set value of the exciting current; and the control device is used for controlling the torque current value of the three-phase asynchronous motor to be equal to the given torque current value and controlling the exciting current value of the three-phase asynchronous motor to be equal to the given exciting current value according to the inquired given torque current value, so that the control of the output torque of the three-phase asynchronous motor is realized.

8. The apparatus of claim 7, wherein the acquisition unit comprises a temperature sensor;

the temperature sensor is arranged in the three-phase asynchronous motor.

Technical Field

The invention relates to the technical field of motor control, in particular to a control method and a control device for output torque of a three-phase asynchronous motor.

Background

With the development of control technology, the three-phase asynchronous motor has been widely applied to the field of alternating current transmission due to good static and dynamic properties. In many application fields, torque control needs to be performed on a three-phase asynchronous motor, and the accuracy of output torque becomes a very important performance index for controlling the three-phase asynchronous motor.

In the prior art, the control of the torque of a three-phase asynchronous motor mainly comprises two methods: the method comprises the steps that firstly, a torque sensor is connected with a three-phase asynchronous motor to measure the output torque value of the three-phase asynchronous motor in real time, and the control of the torque of the three-phase asynchronous motor is realized through closed-loop control; the other is a traditional table look-up method, which needs to measure the torque current value and the excitation current value corresponding to different output torques at different rotating speeds in advance, and make the values into a look-up table to be written into a program for query, and the output torque of the three-phase asynchronous motor is controlled by querying the corresponding torque current value and the excitation current value.

However, the two methods for controlling the torque described above have the following disadvantages: during closed-loop control, a torque sensor needs to be installed in the three-phase asynchronous motor, but higher cost is needed for installing the torque sensor, and the system reliability is poorer; the traditional table look-up method only considers the influence of different rotating speeds on torque control (indirectly considers the influence of exciting current on torque control), but in vector control based on rotor magnetic field orientation, the motor torque control is also influenced by motor temperature, and the analysis is as follows: angular frequency of revolution omega_sThe calculation formula is expressed as:

in the formula, R_rIs rotor resistance, L_rIs the rotor inductance, i_TIs torque current, i_MIs the excitation current. Rotor resistance R_rThe influence of the temperature of the motor is large, when the temperature change range of the motor is large, the torque control has large deviation, and the accuracy of the output torque is poor.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a control method and a control device for the output torque of a three-phase asynchronous motor.

The invention provides a control method of output torque of a three-phase asynchronous motor, which comprises the following steps:

under different motor temperature given values, establishing a lookup table of different output torque given values, different exciting current given values and torque current given values;

measuring a motor temperature value of the three-phase asynchronous motor in real time and acquiring an output torque given value and an exciting current given value in real time;

inquiring the set value of the torque current by utilizing an established inquiry table according to the real-time measured motor temperature value and the real-time acquired set value of the output torque and the set value of the exciting current;

and controlling the torque current value of the three-phase asynchronous motor to be equal to the given torque current value and the exciting current value of the three-phase asynchronous motor to be equal to the given exciting current value according to the inquired given torque current value, so as to realize the control of the output torque of the three-phase asynchronous motor.

Further, the establishing of the lookup table of different output torque set values, different excitation current set values and torque current set values under different motor temperature set values specifically includes:

s1: setting the temperature of the motor, the exciting current and the step length of the output torque; determining the value ranges of the motor temperature, the exciting current and the output torque according to the set step lengths of the motor temperature, the exciting current and the output torque;

s2: starting a three-phase asynchronous motor counter-dragging platform and a three-phase asynchronous motor controller, and setting a given rotating speed value of the three-phase asynchronous motor;

s3: setting a motor temperature given value in the value range of the determined motor temperature, and controlling the motor temperature to the motor temperature given value;

s4: after the temperature of the motor is stabilized at a given value of the motor temperature, setting a given value of the exciting current and a given value of the output torque within the value ranges of the determined exciting current and the output torque;

s5: adjusting the given value of the torque current to ensure that the actual output torque value of the three-phase asynchronous motor is equal to the given value of the output torque, and recording the given value of the torque current at the moment;

s6: and respectively modifying the given value of the output torque, the given value of the exciting current and the given value of the motor temperature within the determined value ranges of the output torque, the exciting current and the motor temperature, thereby obtaining a torque current given value query table corresponding to different given values of the exciting current and different given values of the output torque under different given values of the motor temperature.

Further, the method for determining the value ranges of the motor temperature, the exciting current and the output torque specifically comprises the following steps:

determining the value range of the motor temperature, selecting a step length, starting from 30 ℃ according to the selected step length, taking 1 interval point every 1 step length, and generating a motor temperature sequence at least comprising 2 interval points;

determining the value range of the exciting current, selecting a step length, starting from 5A according to the selected step length, taking 1 interval point every 1 step length, and generating an exciting current sequence at least comprising 15 interval points;

determining the value range of the output torque, selecting the step length, starting from-50 Nm according to the selected step length, taking 1 interval point every 1 step length, and generating an excitation current sequence at least comprising 15 interval points.

Further, a torque current given value lookup table corresponding to different excitation current given values and different output torque given values under different motor temperature given values is obtained in S6, and the method specifically includes:

s601: in the value range of the determined output torque, modifying the given value of the output torque from-50 Nm according to the obtained interval points, and repeating the steps S4 and S5 until all the interval points in the output torque sequence are traversed to obtain the query data of the given value of the exciting current and the given value of the torque current corresponding to the given values of different output torques under the given value of the motor temperature;

s602: modifying the given value of the exciting current from 5A according to the obtained interval points within the determined value range of the exciting current, and repeating the steps S4, S5 and S601 until all interval points in the exciting current sequence are traversed to obtain query data of the given value of the torque current corresponding to different given values of the exciting current and different given values of the output torque under the given value of the temperature of the motor;

s603: within the value range of the determined motor temperature, modifying the given value of the motor temperature from 30 ℃ according to the taken interval points, and repeating the steps S3, S104, S5, S601 and S602 until all the interval points in the motor temperature sequence are traversed to obtain query data of the given values of the torque currents corresponding to the given values of the different exciting currents and the given values of the different output torques under the given values of the different motor temperatures;

s604: and establishing a two-dimensional array query table of the torque current given values corresponding to the different exciting current given values and the different output torque given values under the different motor temperature given values according to the obtained query data of the torque current given values corresponding to the different exciting current given values and the different output torque given values under the different motor temperature given values.

Further, the querying a set torque current value by using an established lookup table according to a real-time measured motor temperature value and a real-time acquired output torque set value and excitation current set value specifically includes:

and inquiring the set value of the torque current by using a linear interpolation method by utilizing the established two-dimensional array inquiry table according to the real-time measured motor temperature value and the real-time acquired set value of the output torque and the set value of the exciting current.

Further, a method for measuring a motor temperature value in real time specifically comprises the following steps:

and measuring the motor temperature value of the three-phase asynchronous motor in real time by using a motor temperature sensor, and obtaining the processed motor temperature value after low-pass filtering the acquired motor temperature value.

The invention also provides a control device for the output torque of the three-phase asynchronous motor, which comprises:

the query unit is used for establishing a query table of different output torque given values, different exciting current given values and torque current given values under different motor temperature given values;

the acquisition unit is used for measuring the motor temperature value of the three-phase asynchronous motor in real time;

the control unit is used for acquiring an output torque given value and an exciting current given value in real time; the device is used for inquiring the set value of the torque current by utilizing the established lookup table according to the real-time measured motor temperature value and the real-time acquired set value of the output torque and the set value of the exciting current; and the control device is used for controlling the torque current value of the three-phase asynchronous motor to be equal to the given torque current value and controlling the exciting current value of the three-phase asynchronous motor to be equal to the given exciting current value according to the inquired given torque current value, so that the control of the output torque of the three-phase asynchronous motor is realized.

Further, the acquisition unit comprises a temperature sensor;

the temperature sensor is arranged in the three-phase asynchronous motor.

The invention has the technical effects or advantages that:

the invention provides a control method and a control device for output torque of a three-phase asynchronous motor, wherein a lookup table is established by a rotating speed sensor and a torque sensor which are arranged in a three-phase asynchronous motor counter-dragging platform and a temperature sensor which is arranged in the three-phase asynchronous motor; the method comprises the following steps of measuring the motor temperature of the three-phase asynchronous motor in real time by adopting a temperature sensor arranged in the three-phase asynchronous motor, and acquiring an output torque set value and an exciting current set value in real time by adopting a control algorithm; according to the established lookup table, querying the measured motor temperature, the obtained output torque given value and a torque current given value corresponding to the excitation current given value; and controlling the torque current value of the three-phase asynchronous motor to be equal to the given torque current value and the exciting current value to be equal to the given exciting current value according to the inquired given torque current value, so as to realize the control of the output torque of the three-phase asynchronous motor. The method does not need to install a torque sensor on the three-phase asynchronous motor, so that the cost investment of closed-loop control of output torque is reduced; the influence of exciting current and motor temperature on output torque control is considered, the error of an output torque given value and an actual output torque value is reduced, the output torque control precision is improved, and the defect of low torque control precision caused by the fact that only the influence of different rotating speeds on the output torque control is considered in the traditional table look-up method is overcome.

Drawings

Fig. 1 is a flowchart of a method for controlling output torque of a three-phase asynchronous motor according to an embodiment of the present invention;

fig. 2 is a flowchart of another three-phase asynchronous motor output torque control method provided by the embodiment of the invention;

fig. 3 is a flowchart of another three-phase asynchronous motor output torque control method provided by the embodiment of the invention;

fig. 4 is a block diagram of a three-phase asynchronous motor drag test system provided in an embodiment of the present invention;

FIG. 5 is a schematic diagram of a torque current set point obtained according to a table lookup method according to an embodiment of the present invention;

fig. 6 is a block diagram of an output torque control device of a three-phase asynchronous motor according to an embodiment of the present invention.

In fig. 4 above: the system comprises a direct-current power supply 1, a three-phase asynchronous motor controller 2, a three-phase asynchronous motor built-in temperature sensor 3, a three-phase asynchronous motor counter-dragging platform built-in torque sensor 4, a three-phase asynchronous motor 5 and a three-phase asynchronous motor counter-dragging platform 6.

Detailed Description

In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and the detailed description.

The invention provides a method and a device for controlling the output torque of a three-phase asynchronous motor, aiming at the defect that the output torque of the three-phase asynchronous motor is controlled by adopting closed-loop control and a traditional table look-up method in the prior art, and considering the influence of exciting current and motor temperature on the torque control of the three-phase asynchronous motor.

The embodiment provides a method for controlling output torque of a three-phase asynchronous motor, and with reference to fig. 1, the method includes the following steps:

p1: under different motor temperature given values, establishing a lookup table of different output torque given values, different exciting current given values and torque current given values;

p2: measuring a motor temperature value of the three-phase asynchronous motor in real time and acquiring an output torque given value and an exciting current given value in real time;

p3: inquiring the set value of the torque current by utilizing an established inquiry table according to the real-time measured motor temperature value and the real-time acquired set value of the output torque and the set value of the exciting current;

p4: and controlling the torque current value of the three-phase asynchronous motor to be equal to the given torque current value and the exciting current value of the three-phase asynchronous motor to be equal to the given exciting current value according to the inquired given torque current value, so as to realize the control of the output torque of the three-phase asynchronous motor.

It should be noted that the real-time acquisition of the output torque set value and the excitation current set value is realized without installing a torque sensor in the three-phase asynchronous motor, and the real-time acquisition of the output torque set value and the excitation current set value of the three-phase asynchronous motor can be realized by adopting a corresponding control algorithm according to different application occasions. The real-time obtaining of the given output torque value and the given excitation current value is common knowledge of those skilled in the art, and is not described in detail herein.

According to the method, a torque sensor is not required to be installed on the three-phase asynchronous motor, a query table is established through a rotating speed sensor and a torque sensor which are installed in a three-phase asynchronous motor counter-dragging platform and a temperature sensor which is installed in the three-phase asynchronous motor, the output torque of the three-phase asynchronous motor is controlled through the query table, and the cost input of closed-loop control of the output torque is reduced; the method considers the influence of exciting current and motor temperature on torque control, reduces the error of the output torque given value and the actual output torque value, improves the control precision of the output torque, and avoids the defect of low torque control precision caused by the fact that the traditional table look-up method only considers the influence of different rotating speeds on the output torque control.

With reference to fig. 2 and 4, it should be further understood that, establishing a lookup table of different output torque set values, different excitation current set values and torque current set values under different motor temperature set values specifically includes:

s1: setting the temperature of the motor, the exciting current and the step length of the output torque; determining the value ranges of the motor temperature, the exciting current and the output torque according to the set step lengths of the motor temperature, the exciting current and the output torque;

s2: starting a three-phase asynchronous motor counter-dragging platform and a three-phase asynchronous motor controller, and setting a given rotating speed value of the three-phase asynchronous motor;

s3: setting a motor temperature given value in the value range of the determined motor temperature, and controlling the motor temperature to the motor temperature given value;

s4: after the temperature of the motor is stabilized at a given value of the motor temperature, setting a given value of the exciting current and a given value of the output torque within the value ranges of the determined exciting current and the output torque;

s5: adjusting the given value of the torque current to enable the actual output torque value of the motor to be equal to the given value of the output torque, and recording the given value of the torque current at the moment;

s6: and respectively modifying the given value of the output torque, the given value of the exciting current and the given value of the motor temperature within the determined value ranges of the output torque, the exciting current and the motor temperature, thereby obtaining a torque current given value query table corresponding to different given values of the exciting current and different given values of the output torque under different given values of the motor temperature.

When the three-phase asynchronous motor counter-dragging platform and the motor controller are started, the three-phase asynchronous motor counter-dragging platform works in a rotating speed fixed point mode, and a rotating speed set value is set to be 30% of the rated rotating speed of the three-phase asynchronous motor; when the temperature of the motor is controlled to be the given value of the temperature of the motor, the error is not more than +/-5 ℃, and if the temperature of the motor is lower, the temperature of the motor can be increased in a mode of loading and operating the motor so as to reach the given value of the temperature of the motor; the set excitation current given value set in S4 is specifically: a rotating speed sensor is installed in the three-phase asynchronous motor twin-trawling platform, and the given value of the exciting current can be set by adopting vector control based on the orientation of a rotor magnetic field according to rotating speed information acquired by the rotating speed sensor; when the torque current set value is adjusted in the S5, the output torque value of the three-phase asynchronous motor is collected through a torque sensor arranged in the three-phase asynchronous motor twin-trawling platform, and the corresponding output torque value is displayed in the three-phase asynchronous motor twin-trawling platform in real time until the actual motor output torque value of the three-phase asynchronous motor is equal to the output torque set value.

In the above, the established torque current given value lookup table corresponding to different exciting current given values and different output torque given values under different motor temperature given values fully considers the influence of exciting current and motor temperature on the torque control of the three-phase asynchronous motor, reduces the error of the output torque given value and the actual output torque value, improves the torque control precision, and avoids the defect of low torque control precision caused by only considering the influence of different rotating speeds on the output torque control by the traditional lookup table method.

It should be further understood that, the method for determining the value ranges of the motor temperature, the exciting current and the output torque specifically includes:

s101: determining the value range of the motor temperature, selecting a step length, starting from 30 ℃ according to the selected step length, taking 1 interval point every 1 step length, and generating a motor temperature sequence at least comprising 2 interval points;

s102: determining the value range of the exciting current, selecting a step length, starting from 5A according to the selected step length, taking 1 interval point every 1 step length, and generating an exciting current sequence at least comprising 15 interval points;

s103: determining the value range of the output torque, selecting the step length, starting from-50 Nm according to the selected step length, taking 1 interval point every 1 step length, and generating an excitation current sequence at least comprising 15 interval points.

It should be noted that the order of steps S101, S102, and S103 may be interchanged, or may not be sequential, and may be performed simultaneously. Namely, it may be: s101, determining a value range of the motor temperature, selecting a step length, starting from 30 ℃ according to the selected step length, taking 1 interval point every 1 step length, and generating a motor temperature sequence at least comprising 2 interval points; s102, determining the value range of the output torque, selecting a step length, starting from-50 Nm according to the selected step length, taking 1 interval point every 1 step length, and generating an excitation current sequence at least comprising 15 interval points; s103, determining the value range of the exciting current, selecting a step length, starting from 5A according to the selected step length, taking 1 interval point every 1 step length, and generating an exciting current sequence at least comprising 15 interval points. It can also be: s101, determining a value range of the exciting current, selecting a step length, starting from 5A according to the selected step length, taking 1 interval point every 1 step length, and generating an exciting current sequence at least comprising 15 interval points; s102, determining a value range of the motor temperature, selecting a step length, starting from 30 ℃ according to the selected step length, taking 1 interval point every 1 step length, and generating a motor temperature sequence at least comprising 2 interval points; s103, determining the value range of the output torque, selecting a step length, starting from-50 Nm according to the selected step length, taking 1 interval point every 1 step length, and generating an excitation current sequence at least comprising 15 interval points. The present invention is not limited to the above-listed sequence of steps.

In the above, the step length of the motor temperature is 50 ℃, and the generated motor temperature sequence is 30 ℃, 80 ℃ and 130 ℃; the step size of the exciting current is 5A, and the generated exciting current sequence is 5A, 10A, 15A, … …, 70A, 75A and 80A; the step size of the output torque is 10Nm, and the output torque sequence generated is-50 Nm, -40Nm, -30Nm, … …, 80Nm, 90Nm, 100 Nm. And determining the value ranges of the motor temperature, the exciting current and the output torque according to the set step length of the motor temperature, the exciting current and the output torque. The set step length and the determined value range meet the actual requirements of engineering, the accuracy of output torque control is not influenced, huge measurement data cannot be generated, the occupied memory of the controller is small, and the operation speed is high.

Referring to fig. 3, it should be further understood that, in S6, a lookup table of torque current set values corresponding to different excitation current set values and different output torque set values under different motor temperature set values is obtained, and the lookup table specifically includes:

s601: in the value range of the determined output torque, modifying the given value of the output torque from-50 Nm according to the obtained interval points, and repeating the steps S4 and S5 until all the interval points in the output torque sequence are traversed to obtain the query data of the given value of the exciting current and the given value of the torque current corresponding to the given values of different output torques under the given value of the motor temperature;

s602: modifying the given value of the exciting current from 5A according to the obtained interval points within the determined value range of the exciting current, and repeating the steps S4, S5 and S601 until all interval points in the exciting current sequence are traversed to obtain query data of the given value of the torque current corresponding to different given values of the exciting current and different given values of the output torque under the given value of the temperature of the motor;

s603: within the value range of the determined motor temperature, modifying the given value of the motor temperature from 30 ℃ according to the taken interval points, and repeating the steps S3, S4, S5, S601 and S602 until all the interval points in the motor temperature sequence are traversed to obtain query data of the given values of the torque currents corresponding to different given values of the exciting currents and different given values of the output torques under different given values of the motor temperature;

s604: and establishing a two-dimensional array query table of the torque current given values corresponding to the different exciting current given values and the different output torque given values under the different motor temperature given values according to the obtained query data of the torque current given values corresponding to the different exciting current given values and the different output torque given values under the different motor temperature given values.

It should be noted that, in order to write the established lookup table into the control program of the three-phase asynchronous motor, the established lookup table is in the form of 3 two-dimensional arrays, and each two-dimensional array represents the query data of the torque current set values corresponding to different excitation current set values and different output torque set values under a certain motor temperature set value. The form of the lookup table is shown in table 1, table 2 and table 3, wherein table 1 is a lookup table of the corresponding torque current set value when the motor temperature is 30 ℃; table 2 is a lookup table of torque current set values corresponding to the motor temperature of 80 ℃; and table 3 is a lookup table of torque current set values corresponding to the motor temperature of 130 ℃.

TABLE 1 lookup table for torque current set value corresponding to motor temperature of 30 deg.C

TABLE 2 LOST OF Torque CURRENT SET VALUE LOOK TABLE CORRESPONDING TO MOTOR TEMPERATURE OF 80 deg.C

TABLE 3 lookup table for torque current set value corresponding to motor temperature of 130 deg.C

In the above, by considering the influence of the exciting current and the motor temperature on the output torque control, the lookup tables of different output torque set values, different exciting current set values and torque current set values are established under different motor temperature set values, and according to the lookup tables, the accurate control of the output torque of the motor can be realized, thereby avoiding the defect of low torque control accuracy caused by the fact that the traditional lookup table method only considers the influence of different rotating speeds on the output torque control.

It is further understood that the query of the set torque current value by using the established lookup table according to the real-time measured motor temperature value, the set output torque value and the set excitation current value specifically includes:

and inquiring the set value of the torque current by using a linear interpolation method by using the established two-dimensional array query table according to the motor temperature value, the output torque value and the excitation current value which are measured in real time.

It should be noted that the linear interpolation method refers to a method of connecting straight lines of two known quantities to determine a value of an unknown quantity between the two known quantities. For example, the given value of the torque current is inquired by a linear interpolation method according to the motor temperature value, the given value of the output torque and the given value of the exciting current which are measured in real time.

Motor temperature value T of three-phase asynchronous motor is assumed_emperatureBetween 30 ℃ and 80 ℃, and a given value T of output torque_orqueBetween 90Nm and 100Nm, given value of exciting current i_MBetween 15A and 20AAccording to the established lookup table, the lookup process is as follows:

1) calculating the temperature of 30 ℃, the exciting current of 15A and the output torque T_orqueCorresponding torque current value i_T1。

Wherein: a1 represents the torque current given value corresponding to the motor temperature of 30 ℃, the exciting current of 15A and the output torque of 90 Nm; c1 represents a torque current set value corresponding to a motor temperature of 30 ℃, an exciting current of 15A and an output torque of 100 Nm.

2) Calculating the temperature of 30 ℃, the exciting current of 20A and the output torque T_orqueCorresponding torque current value i_T2。

Wherein: b1 represents the torque current given value corresponding to the motor temperature of 30 ℃, the exciting current of 20A and the output torque of 90 Nm; d1 represents a given torque current value corresponding to a motor temperature of 30 ℃, an exciting current of 20A and an output torque of 100 Nm.

3) According to the obtained i_T1And i_T2Calculating the temperature of the motor to be 30 ℃, and the exciting current i_MOutput torque T_orqueCorresponding torque current value i_T3。

4) Calculating the temperature of 80 ℃, the exciting current of 15A and the output torque T_orqueCorresponding torque current value i_T4。

Wherein: a2 represents the torque current given value corresponding to the motor temperature of 80 ℃, the exciting current of 15A and the output torque of 90 Nm; c2 represents a torque current set value corresponding to a motor temperature of 80 ℃, an exciting current of 15A and an output torque of 100 Nm.

5) Calculating the temperature of 80 ℃, the exciting current of 20A and the output torque T_orqueCorresponding torque current value i_T5。

Wherein: b2 represents the torque current given value corresponding to the motor temperature of 80 ℃, the exciting current of 20A and the output torque of 90 Nm; d2 represents a given torque current value corresponding to a motor temperature of 80 ℃, an exciting current of 20A and an output torque of 100 Nm.

6) According to the obtained i_T4And i_T5Calculating the temperature of the motor at 80 ℃ and the exciting current i_MOutput torque T_orqueCorresponding torque current value i_T6。

7) According to the obtained i_T3And i_T6Calculating the motor temperature T_emperatureExcitation current i_MOutput torque T_orqueCorresponding torque current value i_T。

In the above, by querying the torque current given value by using a linear interpolation method, the corresponding torque current given value can be accurately queried, the motor torque current value is controlled to be equal to the torque current given value according to the queried torque current given value, and the exciting current value is controlled to be equal to the exciting current given value, so that the control of the output torque of the three-phase asynchronous motor is realized, the error between the output torque given value and the actual output torque value is reduced, and the control precision of the output torque is improved.

With reference to fig. 5, it is further understood that the method for measuring the motor temperature value in real time specifically includes:

and measuring the motor temperature value of the three-phase asynchronous motor in real time by using a motor temperature sensor, and obtaining the processed motor temperature value after low-pass filtering the acquired motor temperature value.

It should be noted that, after the lookup table is established, when the output torque of the three-phase asynchronous motor is controlled, the motor temperature needs to be measured in real time by a temperature sensor built in the three-phase asynchronous motor, and in order to avoid output torque fluctuation caused by noise interference acquired by the temperature sensor, low-pass filtering processing needs to be performed on the motor temperature measured by the temperature sensor, so as to obtain the processed motor temperature.

In the above, the influence of the motor temperature on the torque control is considered, the error between the output torque set value and the actual output torque value is reduced, the torque control precision is improved, and meanwhile, a torque sensor is not required to be installed on the three-phase asynchronous motor, so that the cost investment of closed-loop control torque is reduced.

According to the method provided by the embodiment of the invention, a torque sensor is not required to be arranged on the three-phase asynchronous motor, so that the cost investment of closed-loop control torque is reduced; the method considers the influence of exciting current and motor temperature on torque control, reduces the error of the output torque given value and the actual output torque value, improves the torque control precision, and avoids the defect of low torque control precision caused by the fact that the traditional table look-up method only considers the influence of different rotating speeds on the output torque control.

Referring to fig. 6, fig. 6 is a block diagram of a three-phase asynchronous motor output torque control device according to an embodiment of the present invention, where the three-phase asynchronous motor output torque control device includes: the query unit is used for establishing a query table of different output torque given values, different exciting current given values and torque current given values under different motor temperature given values; the acquisition unit is used for measuring the motor temperature value of the three-phase asynchronous motor in real time; the control unit is used for acquiring an output torque given value and an exciting current given value in real time; the device is used for inquiring the set value of the torque current by utilizing the established lookup table according to the real-time measured motor temperature value and the real-time acquired set value of the output torque and the set value of the exciting current; and the control device is used for controlling the torque current value of the three-phase asynchronous motor to be equal to the given torque current value and controlling the exciting current value of the three-phase asynchronous motor to be equal to the given exciting current value according to the inquired given torque current value, so that the control of the output torque of the three-phase asynchronous motor is realized.

It is further to be understood that the acquisition unit comprises a temperature sensor; the temperature sensor is arranged in the three-phase asynchronous motor.

The embodiment device provided by the invention does not need to install a torque sensor on the three-phase asynchronous motor, adopts a query module to establish a query table of different output torque given values, different exciting current given values and torque current given values under different motor temperature given values, measures the motor temperature value of the three-phase asynchronous motor in real time, adopts a related control algorithm to obtain the output torque given value and the exciting current given value in real time, controls the output torque of the three-phase asynchronous motor according to the motor temperature value, the output torque value, the exciting current value and the query table, and reduces the cost input of closed-loop control torque; meanwhile, errors of the output torque set value and the actual output torque value are reduced, the torque control precision is improved, and the defect of low torque control precision caused by the fact that only the influence of different rotating speeds on the output torque control is considered in the traditional table look-up method is overcome.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.