阅读说明：本技术 一种永磁同步电机的转子温度检测方法、系统及装置 (Rotor temperature detection method, system and device of permanent magnet synchronous motor ) 是由 刘旺 陈建明 刘伟良 周闯 刘文斌 马小利 王海浪 苏勇雪 刘刚 时威振 于 2020-06-03 设计创作，主要内容包括：本申请公开了一种永磁同步电机的转子温度检测方法,包括：确定出被测电机在第一状态下的转子损耗P1及第二状态下的转子损耗P2；检测出从第一状态至第二状态的这一过程中被测电机的反电势的变化曲线,并结合被测电机的转子磁钢的磁能积曲线数据,确定出这一过程中被测电机的转子温度变化曲线；根据转子温度变化曲线,P1以及P2,确定出被测电机的转子磁钢的瞬态热阻抗曲线；当被测电机处于工作状态时,基于瞬态热阻抗曲线以及被测电机当前的转子损耗,确定出被测电机的当前的转子温度名称。应用本申请的方案,可以简单方便地确定出永磁同步电机的转子温度。本申请还提供了一种永磁同步电机的转子温度检测系统及装置,具有相应效果。(The application discloses a rotor temperature detection method of a permanent magnet synchronous motor, which comprises the following steps: determining the rotor loss P1 of the tested motor in a first state and the rotor loss P2 of the tested motor in a second state; detecting a change curve of the back electromotive force of the tested motor in the process from the first state to the second state, and determining a rotor temperature change curve of the tested motor in the process by combining the data of the magnetic energy product curve of the rotor magnetic steel of the tested motor; determining a transient thermal impedance curve of the rotor magnetic steel of the tested motor according to the rotor temperature change curve, P1 and P2; and when the tested motor is in a working state, determining the current rotor temperature name of the tested motor based on the transient thermal impedance curve and the current rotor loss of the tested motor. By the scheme, the rotor temperature of the permanent magnet synchronous motor can be determined simply and conveniently. The application also provides a system and a device for detecting the rotor temperature of the permanent magnet synchronous motor, and the system and the device have corresponding effects.)

1. A rotor temperature detection method of a permanent magnet synchronous motor is characterized by comprising the following steps:

determining the rotor loss P1 of the tested motor in a preset first state;

controlling the tested motor to enter a preset second state, and determining the rotor loss P2 of the tested motor in the second state;

detecting a change curve of the back electromotive force of the tested motor in the process from the first state to the second state, and determining a rotor temperature change curve of the tested motor in the process from the first state to the second state by combining magnetic energy product curve data of rotor magnetic steel of the tested motor;

determining a transient thermal impedance curve of rotor magnetic steel of the tested motor according to the rotor temperature change curve, the rotor loss P1 in the first state and the rotor loss P2 in the second state;

and when the tested motor is in a working state, determining the current rotor temperature of the tested motor based on the transient thermal impedance curve and the current rotor loss of the tested motor.

2. The method of claim 1, wherein the rotor loss P1 in the first state is less than the rotor loss P2 in the second state.

3. The method of claim 2, wherein the rotor loss P1 in the first state is 0.

4. The method for detecting the rotor temperature of the permanent magnet synchronous motor according to claim 1, wherein the rotor loss P1 of the motor to be detected in a preset first state is determined; controlling the tested motor to enter a preset second state, and determining the rotor loss P2 of the tested motor in the second state, wherein the method comprises the following steps:

dragging the rotating speed of a tested motor to a preset first rotating speed by a dragging motor, controlling the tested motor to output preset power, determining that the tested motor is in a first state when the tested motor continuously runs to be thermally stable, and determining the rotor loss P1 of the tested motor in the first state;

and controlling the tested motor to seal the pipe and keeping the rotating speed of the dragging motor unchanged until the temperature of the tested motor is reduced to be thermally stable, determining that the tested motor is in a second state, and determining the rotor loss P2 of the tested motor in the second state.

5. The method for detecting the rotor temperature of the permanent magnet synchronous motor according to claim 4, wherein the step of determining the rotor loss P1 of the motor to be detected in the first state comprises the following steps:

and determining the rotor loss P1 of the tested motor in the first state by a finite element simulation method based on the electrical parameter information of the tested motor in the first state.

6. The method according to claim 4, wherein the first rotation speed is a rotation speed lower than a turning rotation speed, and the preset power is a rated power of the motor under test.

7. The method of claim 1, wherein the detecting a change curve of a back electromotive force of the motor under test in the process from the first state to the second state, and determining a change curve of a rotor temperature of the motor under test in the process from the first state to the second state by combining magnetic energy product curve data of rotor magnetic steel of the motor under test, comprises:

detecting a change curve of the back electromotive force of the motor under test in the process from the first state to the second state;

determining a rotor temperature change curve of the tested motor in the process from the first state to the second state;

determining the magnetic induction B at any moment in the process from the first state to the second state through 4.44fNSB ═ E, and determining the rotor temperature of the measured motor at the moment through the determined magnetic induction B at the moment and the magnetic energy product curve data of the rotor magnetic steel of the measured motor;

f represents the running frequency of the tested motor, N represents the number of turns of a stator winding of the tested motor, S represents the cross section area of a stator coil of the tested motor, B represents the magnetic induction intensity of the tested motor, and E represents the counter electromotive force of the tested motor.

8. A rotor temperature detection system of a permanent magnet synchronous motor is characterized by comprising:

the rotor loss P1 determining module is used for determining the rotor loss P1 of the tested motor in a preset first state;

the rotor loss P2 determining module is used for controlling the tested motor to enter a preset second state and determining the rotor loss P2 of the tested motor in the second state;

the rotor temperature change curve determining module is used for detecting a change curve of back electromotive force of the tested motor in the process from the first state to the second state and determining the rotor temperature change curve of the tested motor in the process from the first state to the second state by combining with magnetic energy product curve data of rotor magnetic steel of the tested motor;

the rotor magnetic steel transient thermal impedance curve determining module is used for determining a transient thermal impedance curve of the rotor magnetic steel of the tested motor according to the rotor temperature change curve, the rotor loss P1 in the first state and the rotor loss P2 in the second state;

and the rotor temperature detection module is used for determining the current rotor temperature of the tested motor based on the transient thermal impedance curve and the current rotor loss of the tested motor when the tested motor is in a working state.

9. The rotor temperature detection system of a permanent magnet synchronous motor according to claim 8, wherein a rotor loss P1 in the first state is smaller than a rotor loss P2 in the second state.

10. The system of claim 9, wherein the rotor loss P1 in the first state is 0.

11. The system of claim 8, wherein the rotor loss P1 determination module is specifically configured to:

dragging the rotating speed of a tested motor to a preset first rotating speed by a dragging motor, controlling the tested motor to output preset power, determining that the tested motor is in a first state when the tested motor continuously runs to be thermally stable, and determining the rotor loss P1 of the tested motor in the first state;

the rotor loss P2 determination module is specifically configured to:

and controlling the tested motor to seal the pipe and keeping the rotating speed of the dragging motor unchanged until the temperature of the tested motor is reduced to be thermally stable, determining that the tested motor is in a second state, and determining the rotor loss P2 of the tested motor in the second state.

12. The system of claim 11, wherein the rotor loss P1 determination module is specifically configured to:

the method comprises the steps that the rotating speed of a tested motor is dragged to a preset first rotating speed by a dragging motor, the tested motor is controlled to output preset power, when the tested motor continuously runs to be thermally stable, the tested motor is determined to be in a first state, and the rotor loss P1 of the tested motor in the first state is determined through a finite element simulation method on the basis of electrical parameter information of the tested motor in the first state.

13. The system of claim 11, wherein the first rotational speed is a rotational speed lower than a turning rotational speed, and the predetermined power is a rated power of the motor under test.

14. The system for detecting the rotor temperature of the permanent magnet synchronous motor according to claim 8, wherein the rotor temperature variation curve determining module is specifically configured to:

detecting a change curve of the back electromotive force of the motor under test in the process from the first state to the second state;

determining a rotor temperature change curve of the tested motor in the process from the first state to the second state;

determining the magnetic induction B at any moment in the process from the first state to the second state through 4.44fNSB ═ E, and determining the rotor temperature of the measured motor at the moment through the determined magnetic induction B at the moment and the magnetic energy product curve data of the rotor magnetic steel of the measured motor;

f represents the running frequency of the tested motor, N represents the number of turns of a stator winding of the tested motor, S represents the cross section area of a stator coil of the tested motor, B represents the magnetic induction intensity of the tested motor, and E represents the counter electromotive force of the tested motor.

15. A rotor temperature detection device of a permanent magnet synchronous motor is characterized by comprising:

a memory for storing a computer program;

a processor for executing the computer program for carrying out the steps of the method of detecting the rotor temperature of a permanent magnet synchronous machine according to any of claims 1 to 7.

Technical Field

The invention relates to the technical field of permanent magnet motors, in particular to a method, a system and a device for detecting the temperature of a rotor of a permanent magnet synchronous motor.

Background

With the application and development of electric vehicles, a permanent magnet synchronous motor becomes a mainstream scheme in China and even all over the world as a driving motor of the electric vehicle. Along with the miniaturization and the light weight of the electric automobile driving system, the higher the motor rotating speed is, the higher the power density of the motor is, the higher the temperature of the magnetic steel of the motor rotor is, and the magnetic loss risk is caused, so that the unprecedented challenge is provided for the thermal reliability of the motor.

When the motor is designed, the temperature and the temperature rise curve of the rotor of the motor need to be tested and found. Due to the structural characteristics of the motor rotor, the rotor is in a rotating state, and the temperature of the motor rotor is difficult to measure.

Some current solutions detect the rotor temperature by means of an infrared sensor, which is costly for electric vehicles. And an infrared temperature measurement mode based on optical reflection is adopted, so that the circuit is complex, the cost is high, and the method is not suitable for electric automobiles. The temperature measurement is realized by connecting a built-in temperature-sensitive resistor to the outside through a wire for resistance measurement, and the temperature measurement is difficult to realize because the temperature-sensitive resistor needs to be embedded and a slot is required to be formed in the rotor magnetic steel.

In summary, how to more conveniently and effectively detect the rotor temperature of the permanent magnet synchronous motor is a technical problem which needs to be solved urgently by those skilled in the art at present.

Disclosure of Invention

The invention aims to provide a method, a system and a device for detecting the rotor temperature of a permanent magnet synchronous motor, so as to more conveniently and effectively detect the rotor temperature of the permanent magnet synchronous motor.

In order to solve the technical problems, the invention provides the following technical scheme:

a rotor temperature detection method of a permanent magnet synchronous motor comprises the following steps:

determining the rotor loss P1 of the tested motor in a preset first state;

controlling the tested motor to enter a preset second state, and determining the rotor loss P2 of the tested motor in the second state;

detecting a change curve of the back electromotive force of the tested motor in the process from the first state to the second state, and determining a rotor temperature change curve of the tested motor in the process from the first state to the second state by combining magnetic energy product curve data of rotor magnetic steel of the tested motor;

determining a transient thermal impedance curve of rotor magnetic steel of the tested motor according to the rotor temperature change curve, the rotor loss P1 in the first state and the rotor loss P2 in the second state;

and when the tested motor is in a working state, determining the current rotor temperature of the tested motor based on the transient thermal impedance curve and the current rotor loss of the tested motor.

Preferably, the rotor loss P1 in the first state is smaller than the rotor loss P2 in the second state.

Preferably, the rotor loss P1 in the first state is 0.

Preferably, the rotor loss P1 of the tested motor in a preset first state is determined; controlling the tested motor to enter a preset second state, and determining the rotor loss P2 of the tested motor in the second state, wherein the method comprises the following steps:

dragging the rotating speed of a tested motor to a preset first rotating speed by a dragging motor, controlling the tested motor to output preset power, determining that the tested motor is in a first state when the tested motor continuously runs to be thermally stable, and determining the rotor loss P1 of the tested motor in the first state;

and controlling the tested motor to seal the pipe and keeping the rotating speed of the dragging motor unchanged until the temperature of the tested motor is reduced to be thermally stable, determining that the tested motor is in a second state, and determining the rotor loss P2 of the tested motor in the second state.

Preferably, the determining the rotor loss P1 of the tested motor in the first state includes:

and determining the rotor loss P1 of the tested motor in the first state by a finite element simulation method based on the electrical parameter information of the tested motor in the first state.

Preferably, the first rotating speed is a rotating speed lower than the turning rotating speed, and the preset power is a rated power of the tested motor.

Preferably, the detecting a change curve of a back electromotive force of the measured motor in the process from the first state to the second state and determining a change curve of a rotor temperature of the measured motor in the process from the first state to the second state by combining magnetic energy product curve data of rotor magnetic steel of the measured motor comprises:

detecting a change curve of the back electromotive force of the motor under test in the process from the first state to the second state;

determining a rotor temperature change curve of the tested motor in the process from the first state to the second state;

determining the magnetic induction B at any moment in the process from the first state to the second state through 4.44fNSB ═ E, and determining the rotor temperature of the measured motor at the moment through the determined magnetic induction B at the moment and the magnetic energy product curve data of the rotor magnetic steel of the measured motor;

f represents the running frequency of the tested motor, N represents the number of turns of a stator winding of the tested motor, S represents the cross section area of a stator coil of the tested motor, B represents the magnetic induction intensity of the tested motor, and E represents the counter electromotive force of the tested motor.

Preferably, the method comprises the following steps:

the rotor loss P1 determining module is used for determining the rotor loss P1 of the tested motor in a preset first state;

the rotor loss P2 determining module is used for controlling the tested motor to enter a preset second state and determining the rotor loss P2 of the tested motor in the second state;

the rotor temperature change curve determining module is used for detecting a change curve of back electromotive force of the tested motor in the process from the first state to the second state and determining the rotor temperature change curve of the tested motor in the process from the first state to the second state by combining with magnetic energy product curve data of rotor magnetic steel of the tested motor;

the rotor magnetic steel transient thermal impedance curve determining module is used for determining a transient thermal impedance curve of the rotor magnetic steel of the tested motor according to the rotor temperature change curve, the rotor loss P1 in the first state and the rotor loss P2 in the second state;

and the rotor temperature detection module is used for determining the current rotor temperature of the tested motor based on the transient thermal impedance curve and the current rotor loss of the tested motor when the tested motor is in a working state.

Preferably, the rotor loss P1 in the first state is smaller than the rotor loss P2 in the second state.

Preferably, the rotor loss P1 in the first state is 0.

Preferably, the rotor loss P1 determination module is specifically configured to:

dragging the rotating speed of a tested motor to a preset first rotating speed by a dragging motor, controlling the tested motor to output preset power, determining that the tested motor is in a first state when the tested motor continuously runs to be thermally stable, and determining the rotor loss P1 of the tested motor in the first state;

the rotor loss P2 determination module is specifically configured to:

and controlling the tested motor to seal the pipe and keeping the rotating speed of the dragging motor unchanged until the temperature of the tested motor is reduced to be thermally stable, determining that the tested motor is in a second state, and determining the rotor loss P2 of the tested motor in the second state.

Preferably, the rotor loss P1 determination module is specifically configured to:

the method comprises the steps that the rotating speed of a tested motor is dragged to a preset first rotating speed by a dragging motor, the tested motor is controlled to output preset power, when the tested motor continuously runs to be thermally stable, the tested motor is determined to be in a first state, and the rotor loss P1 of the tested motor in the first state is determined through a finite element simulation method on the basis of electrical parameter information of the tested motor in the first state.

Preferably, the first rotating speed is a rotating speed lower than the turning rotating speed, and the preset power is a rated power of the tested motor.

Preferably, the rotor temperature variation curve determining module is specifically configured to:

detecting a change curve of the back electromotive force of the motor under test in the process from the first state to the second state;

determining a rotor temperature change curve of the tested motor in the process from the first state to the second state;

determining the magnetic induction B at any moment in the process from the first state to the second state through 4.44fNSB ═ E, and determining the rotor temperature of the measured motor at the moment through the determined magnetic induction B at the moment and the magnetic energy product curve data of the rotor magnetic steel of the measured motor;

f represents the running frequency of the tested motor, N represents the number of turns of a stator winding of the tested motor, S represents the cross section area of a stator coil of the tested motor, B represents the magnetic induction intensity of the tested motor, and E represents the counter electromotive force of the tested motor.

A rotor temperature detection device of a permanent magnet synchronous motor includes:

a memory for storing a computer program;

a processor for executing the computer program to implement the steps of the method for detecting the rotor temperature of a permanent magnet synchronous motor according to any one of the above.

By applying the technical scheme provided by the embodiment of the invention, the corresponding relation between the temperature and the magnetic field intensity can be obtained according to the magnetic energy product characteristic curve of the permanent magnet, and the magnetic field intensity can be obtained according to the back electromotive force of the motor, so that after the change curve of the back electromotive force of the tested motor in the process from the first state to the second state is detected, the transient thermal impedance curve of the rotor magnetic steel of the tested motor can be conveniently determined by combining the rotor loss P1 of the tested motor in the preset first state and the rotor loss P2 of the tested motor in the second state. The transient thermal impedance curve of the rotor magnetic steel of the tested motor can reflect the temperature change condition of the process that the rotor loss rises from P1 to P2, so that when the tested motor is in a working state, the current rotor temperature of the tested motor can be determined based on the transient thermal impedance curve and the current rotor loss of the tested motor. The scheme of the application can accurately determine the thermal impedance characteristic of the tested motor, is simple, does not need to additionally increase a sensor, does not need to perform any special treatment on the tested motor, and can simply and conveniently determine the rotor temperature of the permanent magnet synchronous motor.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a flowchart of an embodiment of a method for detecting a rotor temperature of a permanent magnet synchronous motor according to the present invention;

FIG. 2 is a graph of applied step loss power and measured rotor temperature for an electric machine in accordance with one embodiment;

FIG. 3 is a graph of magnetic energy product curves of a specific type of permanent magnet steel;

fig. 4 is a schematic structural diagram of a rotor temperature detection system of a permanent magnet synchronous motor according to the present invention.

Detailed Description

The core of the invention is to provide a rotor temperature detection method of a permanent magnet synchronous motor, which can simply and conveniently determine the rotor temperature of the permanent magnet synchronous motor.

In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a flowchart illustrating an implementation of a method for detecting a rotor temperature of a permanent magnet synchronous motor according to the present invention, where the method for detecting the rotor temperature of the permanent magnet synchronous motor includes the following steps:

step S101: and determining the rotor loss P1 of the tested motor in a preset first state.

Step S102: and controlling the tested motor to enter a preset second state, and determining the rotor loss P2 of the tested motor in the second state.

Generally, the tested motor can be switched to the second state from the preset first state by applying a step loss power, i.e. the rotor loss P1 in the first state can be smaller than the rotor loss P2 in the second state. For example, the coordinate axis C1 in FIG. 2 is P1 smaller than P2.

It should be noted that the measured motor is in a preset first state, which indicates that the measured motor is thermally stable in the first state, and correspondingly, the measured motor is controlled to enter a preset second state, which means that the measured motor is considered to be in the second state after being thermally stable, that is, a process, namely a process of temperature change, is required for the measured motor to move from the first state to the second state.

It should be noted that, when the rotor loss P1 in the first state is smaller than the rotor loss P2 in the second state, the rotor loss P1 in the first state is usually set to 0, that is, in this embodiment, the state where the motor to be measured is not running is taken as the first state, then a step loss power is applied, the rotor temperature rises continuously, and after thermal stabilization, the motor to be measured is in the second state.

When determining the rotor loss of the tested motor in the first state and the second state, the determination may be generally performed by using finite element simulation software, and of course, other determination methods may be used in other embodiments, which do not affect the implementation of the present invention, as long as the purpose of the present application is achieved.

Step S103: and detecting a change curve of the back electromotive force of the tested motor in the process from the first state to the second state, and determining a rotor temperature change curve of the tested motor in the process from the first state to the second state by combining the magnetic energy product curve data of the rotor magnetic steel of the tested motor.

For example, a coordinate axis C2 in fig. 2 represents a temperature variation curve of the rotor of the measured motor determined in the embodiment.

Specifically, a change curve of the back electromotive force of the motor under test in the process from the first state to the second state may be detected, for example, in the process, the back electromotive force of the motor under test is detected every 0.1 second, and then the change curve of the back electromotive force of the motor under test in the process may be obtained by fitting.

The relation between rotor magnet steel temperature and magnetic induction intensity can be reflected to the magnetic energy product curve data of the rotor magnet steel of the measured motor, and to a specific one measured motor, the relation between the counter electromotive force and the magnetic induction intensity of the measured motor can be determined, so that the determined counter electromotive force change curve is utilized, and the rotor temperature change curve of the measured motor in the process from the first state to the second state can be determined by combining the magnetic energy product curve data of the rotor magnet steel of the measured motor.

For example, fig. 3 shows data of a magnetic energy product curve of a certain type of permanent magnet steel, where the horizontal axis represents the magnetic coercive force Hcb and the vertical axis represents the magnetic induction intensity. For any time in the process from the first state to the second state, the magnetic induction intensity at the time can be calculated according to the counter electromotive force of the measured motor at the time, and for the specific motor, the magnetic induction coercive force Hcb is a value which can be determined, so that the rotor temperature value at the time can be determined based on the magnetic energy product curve data of the rotor magnetic steel of the measured motor. Since the rotor temperature value at each time point in the process from the first state to the second state can be determined, for example, a plurality of time points are periodically selected, and then a rotor temperature change curve of the measured motor in the process from the first state to the second state can be determined by means of fitting.

Step S104: and determining a transient thermal impedance curve of the rotor magnetic steel of the tested motor according to the rotor temperature change curve, the rotor loss P1 in the first state and the rotor loss P2 in the second state.

The transient thermal impedance curve of the rotor magnetic steel of the tested motor represents the temperature increase condition of the rotor magnetic steel of the tested motor caused by the increase of the rotor loss.

Therefore, when the rotor loss P1 in the first state is smaller than the rotor loss P2 in the second state, the rotor temperature variation curve obtained in step S103 is a curve in which the temperature value is in an increasing state, as is the case with fig. 2, for example. At this time, the temperature variation curve of the rotor is divided by P2-P1, and then the temperature value of the measured motor in the first state is subtracted from the obtained curve, namely the measured motor is translated in the negative direction of the y axis, so that after the translation, when t is 0, the function value of the curve is 0, and the transient thermal impedance curve of the rotor magnetic steel of the measured motor can be obtained. That is to say, the transient thermal impedance curve of the rotor magnetic steel of the measured motor can be obtained by dividing Δ T by Δ P and subtracting the temperature value of the measured motor in the first state from the obtained curve. Δ T represents a difference between the temperature value at the T-th time and the temperature value at the time when T is 0, T represents time, i.e., a time when T is 0, i.e., a trigger time when the motor under test is switched from the first state to the second state, and Δ P represents P2 to P1. It should be noted that if P1 is equal to 0, the transient thermal impedance curve of the rotor magnetic steel of the measured motor is obtained by dividing Δ T by Δ P and then subtracting the ambient temperature from the obtained curve.

Accordingly, when the rotor loss P1 in the first state is greater than the rotor loss P2 in the second state, the rotor temperature variation curve obtained in step S103 is a curve with a temperature value in a falling state, and at this time, the rotor temperature variation curve obtained in step S103 may be firstly reversed along the y-axis and then shifted in the positive direction of the x-axis until the time when t is 0 is taken as the starting point of the curve. And dividing the obtained curve by P1-P2, and subtracting the temperature value of the tested motor in the second state, namely translating in the negative direction of the y axis, so that the function value of the time curve when t is 0 after translation is 0, thereby obtaining the transient thermal impedance curve of the rotor magnetic steel of the tested motor.

Step S105: and when the tested motor is in a working state, determining the current rotor temperature of the tested motor based on the transient thermal impedance curve and the current rotor loss of the tested motor.

Because the transient thermal impedance curve is determined, when the tested motor is in a working state, the current rotor temperature of the tested motor can be determined based on the transient thermal impedance curve and the current rotor loss of the tested motor.

For example, if the current rotor loss of the motor under test is a and thermally stable, a is multiplied by the transient thermal impedance curve, and the obtained curve can reflect the temperature rise of the rotor of the motor under test after the rotor enters the state of the rotor loss a from the non-operating state, and the maximum value of the curve is the thermally stable temperature of the motor under test in the operating state of the rotor loss a.

Further, in an embodiment of the present invention, the step S101 and the step S102 may specifically include:

the first step is as follows: dragging the rotating speed of the tested motor to a preset first rotating speed by the dragging motor, controlling the tested motor to output preset power, determining that the tested motor is in a first state when the tested motor continuously runs to be thermally stable, and determining the rotor loss P1 of the tested motor in the first state;

the second step is that: and controlling the pipe sealing of the tested motor and keeping the rotating speed of the dragging motor unchanged until the temperature of the tested motor is reduced to be thermally stable, determining that the tested motor is in the second state, and determining the rotor loss P2 of the tested motor in the second state.

In this embodiment, considering that the scheme of the present application needs to detect the change curve of the back electromotive force of the measured motor in the process from the first state to the second state, the change curve of the rotor temperature of the measured motor in the process from the first state to the second state can be determined by combining the data of the magnetic energy product curve of the rotor magnetic steel of the measured motor. Therefore, the accuracy of the detected back electromotive force of the motor under test affects the accuracy of the scheme of the application. However, if a step loss power is applied in one embodiment as shown in the above figure, i.e., P1 is less than P2, it is difficult to accurately measure the back electromotive force of the measured motor because the measured motor has an armature reflection of the orthogonal/orthogonal axes during outputting torque and power. Therefore, in this embodiment, the scheme is further optimized, so that the change curve of the counter electromotive force of the motor to be measured can be accurately determined, and the error is reduced.

Specifically, the rotation speed of the tested motor can be dragged to a preset first rotation speed by the pair-dragging motor on the pair-dragging table, the tested motor is controlled to output a preset power, when the continuous operation is stable to heat, the tested motor is determined to be in the first state, and the rotor loss P1 of the tested motor in the first state is determined.

The specific value of the preset power can be set according to actual needs, for example, the preset power can be set as the rated power of the motor to be tested.

In addition, when determining the rotor loss P1 of the measured motor in the first state, the rotor loss P1 can be determined by a finite element simulation method. That is, in an embodiment of the present invention, the operation of determining the rotor loss P1 of the measured motor in the first state may specifically include:

and determining the rotor loss P1 of the tested motor in the first state by a finite element simulation method based on the electrical parameter information of the tested motor in the first state.

The implementation mode can be generally realized through finite element simulation software, the implementation is simple and easy, and the rotor core loss and the permanent magnet eddy current loss of the tested motor can be determined through a finite element simulation method, and the total is the rotor loss P1 of the tested motor in the first state.

In this embodiment, the detected motor is controlled to seal the pipe and the rotation speed of the dragging motor is kept unchanged until the temperature of the detected motor is reduced to be thermally stable, and the detected motor is determined to be in the second state, so that the rotor loss P2 of the detected motor in the second state is equal to 0. It is understood that P1 is greater than P2, and therefore in this embodiment, the obtained rotor temperature variation curve is a curve with a temperature value in a falling state, and therefore, as described above, the obtained rotor temperature variation curve can be firstly flipped along the y-axis and then translated in the positive direction of the x-axis until the time when t is equal to 0 serves as the starting point of the curve. And then dividing the obtained curve by P1-P2 (P1-0) which is P1), and then subtracting the temperature value of the tested motor in the second state, namely translating the temperature value in the negative direction of the y axis, thereby finally obtaining the transient thermal impedance curve of the rotor magnetic steel of the tested motor.

And it should be emphasized that, in this embodiment, after the tube sealing of the motor to be measured is controlled, the motor to be measured is switched from the first state to the second state, so in this process, the line voltage of the motor to be measured is the back electromotive force, and the effective value of the line voltage of the motor to be measured can be directly collected by the voltage sensor, for example, every 0.1 second, so that an accurate back electromotive force variation curve of the motor to be measured in this process from the first state to the second state can be obtained, and the accuracy of the scheme is improved.

In addition, in this embodiment, since the motor under test is in a sealed condition during the first state to the second state, the magnetically induced coercive force Hcb is always equal to 0 when the rotor temperature variation curve of the motor under test is determined by using the variation curve of the back electromotive force and combining the magnetic energy product curve data of the rotor magnetic steel of the motor under test.

The specific value of the first rotation speed can also be set according to actual needs, but generally, the first rotation speed should be a rotation speed lower than the turning rotation speed so as to avoid that the counter potential of the tested motor is higher than the direct current bus voltage of the tested motor. For example, a higher rotational speed value below the breakover rotational speed can be selected.

In an embodiment of the present invention, step S103 may specifically include:

detecting a change curve of the back electromotive force of the detected motor in the process from the first state to the second state;

determining a rotor temperature change curve of the tested motor in the process from the first state to the second state;

determining the magnetic induction B at any moment in the process from the first state to the second state through 4.44fNSB ═ E, and determining the rotor temperature of the measured motor at the moment through the determined magnetic induction B at the moment and the magnetic energy product curve data of the rotor magnetic steel of the measured motor;

f represents the running frequency of the tested motor, N represents the number of turns of a stator winding of the tested motor, S represents the cross section area of a stator coil of the tested motor, B represents the magnetic induction intensity of the tested motor, and E represents the counter potential of the tested motor.

In this embodiment, since the change curve of the back electromotive force of the motor under test in the process from the first state to the second state is detected, the magnetic induction B at any time in the process from the first state to the second state can be determined by 4.44fNSB ═ E, and therefore, the rotor temperature at that time can be determined using the magnetic energy product curve data of the rotor magnetic steel of the motor under test at any time.

By applying the technical scheme provided by the embodiment of the invention, the corresponding relation between the temperature and the magnetic field intensity can be obtained according to the magnetic energy product characteristic curve of the permanent magnet, and the magnetic field intensity can be obtained according to the back electromotive force of the motor, so that after the change curve of the back electromotive force of the tested motor in the process from the first state to the second state is detected, the transient thermal impedance curve of the rotor magnetic steel of the tested motor can be conveniently determined by combining the rotor loss P1 of the tested motor in the preset first state and the rotor loss P2 of the tested motor in the second state. The transient thermal impedance curve of the rotor magnetic steel of the tested motor can reflect the temperature change condition of the process that the rotor loss rises from P1 to P2, so that when the tested motor is in a working state, the current rotor temperature of the tested motor can be determined based on the transient thermal impedance curve and the current rotor loss of the tested motor. The scheme of the application can accurately determine the thermal impedance characteristic of the tested motor, is simple, does not need to additionally increase a sensor, does not need to perform any special treatment on the tested motor, and can simply and conveniently determine the rotor temperature of the permanent magnet synchronous motor.

Corresponding to the above method embodiment, the embodiment of the present invention further provides a rotor temperature detection system of a permanent magnet synchronous motor, which can be referred to in correspondence with the above.

Referring to fig. 4, a schematic structural diagram of a rotor temperature detection system of a permanent magnet synchronous motor according to the present invention includes:

a rotor loss P1 determining module 401, configured to determine a rotor loss P1 of the measured motor in a preset first state;

a rotor loss P2 determining module 402, configured to control the measured motor to enter a preset second state, and determine a rotor loss P2 of the measured motor in the second state;

a rotor temperature change curve determining module 403, configured to detect a change curve of a back electromotive force of the measured motor in a process from the first state to the second state, and determine a rotor temperature change curve of the measured motor in the process from the first state to the second state by combining with magnetic energy product curve data of rotor magnetic steel of the measured motor;

the rotor magnetic steel transient thermal impedance curve determining module 404 is configured to determine a transient thermal impedance curve of the rotor magnetic steel of the measured motor according to a rotor temperature change curve, a rotor loss P1 in the first state, and a rotor loss P2 in the second state;

and the rotor temperature detection module 405 is configured to determine a current rotor temperature of the measured motor based on the transient thermal impedance curve and the current rotor loss of the measured motor when the measured motor is in the working state.

In one embodiment of the invention, the rotor loss P1 in the first state is less than the rotor loss P2 in the second state.

In one embodiment of the present invention, the rotor loss P1 in the first state is 0.

In an embodiment of the present invention, the rotor loss P1 determination module 401 is specifically configured to:

dragging the rotating speed of the tested motor to a preset first rotating speed by the dragging motor, controlling the tested motor to output preset power, determining that the tested motor is in a first state when the tested motor continuously runs to be thermally stable, and determining the rotor loss P1 of the tested motor in the first state;

the rotor loss P2 determination module 402 is specifically configured to:

and controlling the pipe sealing of the tested motor and keeping the rotating speed of the dragging motor unchanged until the temperature of the tested motor is reduced to be thermally stable, determining that the tested motor is in the second state, and determining the rotor loss P2 of the tested motor in the second state.

In an embodiment of the present invention, the rotor loss P1 determination module 401 is specifically configured to:

the method comprises the steps that the rotating speed of a tested motor is dragged to a preset first rotating speed through a dragging motor, the tested motor is controlled to output preset power, when the tested motor continuously runs to be thermally stable, the tested motor is determined to be in a first state, and based on electrical parameter information of the tested motor in the first state, the rotor loss P1 of the tested motor in the first state is determined through a finite element simulation method.

In one embodiment of the present invention, the first rotation speed is a rotation speed lower than the turning rotation speed, and the preset power is a rated power of the motor to be measured.

In an embodiment of the present invention, the rotor temperature variation curve determining module 403 is specifically configured to:

detecting a change curve of the back electromotive force of the detected motor in the process from the first state to the second state;

determining a rotor temperature change curve of the tested motor in the process from the first state to the second state;

determining the magnetic induction B at any moment in the process from the first state to the second state through 4.44fNSB ═ E, and determining the rotor temperature of the measured motor at the moment through the determined magnetic induction B at the moment and the magnetic energy product curve data of the rotor magnetic steel of the measured motor;

f represents the running frequency of the tested motor, N represents the number of turns of a stator winding of the tested motor, S represents the cross section area of a stator coil of the tested motor, B represents the magnetic induction intensity of the tested motor, and E represents the counter potential of the tested motor.

Corresponding to the above method and system embodiments, the embodiments of the present invention further provide a device for detecting a rotor temperature of a permanent magnet synchronous motor, which can be referred to in correspondence with the above.

The rotor temperature detection apparatus of a permanent magnet synchronous motor may include:

a memory for storing a computer program;

a processor for executing a computer program to implement the steps of the rotor temperature detection method of the permanent magnet synchronous motor in any of the above embodiments.

It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. The principle and the implementation of the present invention are explained in the present application by using specific examples, and the above description of the embodiments is only used to help understanding the technical solution and the core idea of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.