KR102030188B1 - Apparatus and Method for estimating rotor temperature of motor - Google Patents

Abstract

The present invention relates to a permanent magnet motor, and more particularly, to an apparatus and method for estimating the rotor temperature of a permanent magnet motor to estimate the temperature of the rotor (magnet) of the motor using the permanent magnet to increase the efficiency and torque accuracy of the motor. It is about.
According to the present invention, it is possible to accurately measure the rotor temperature compared to the conventional calculation method using the loss, heat resistance and heat capacity, thereby improving the motor torque control accuracy and efficiency.

Description

Apparatus and Method for estimating rotor temperature of motor}

The present invention relates to a permanent magnet motor, and more particularly, to a motor rotor temperature estimation device and method for estimating the temperature of the rotor (magnet) of the motor using the permanent magnet to increase the efficiency and torque accuracy of the motor.

The present invention also relates to a motor rotor temperature estimating apparatus and method for estimating the temperature of a rotor (magnet) using a current-voltage relationship equation of a permanent magnet motor.

As a technique for estimating the temperature of a rotor of a motor, Korean Patent Publication No. 10-2012-0083443 (name of the invention: a method for estimating the temperature of a stator and a rotor in a rotating electric machine in real time), Korean Patent Publication No. 10-2012-0059263, Korea Patent Publication No. 10-2012-0109294 and the like.

The drawings illustrating the concept of Korean Patent Laid-Open No. 10-2012-0083443 are shown in FIGS. 1 and 2. Referring to FIG. 1, a drive shaft 12 arranged longitudinally at the rear, at least one driven shaft 14 arranged at the front, a friction clutch system 10 designed to connect with the driven shaft, a circular radial response A coaxial friction disk 22 inserted between the plate 16 and the front annular pressure plate 20, a diaphragm 24 for arranging the front annular pressure plate at the rear, an annular stop 28 for the operation of the clutch, and an annular stop ( And a rotary machine 30 for controlling 28.

2, the rotating machine 30 is composed of a stator 36, a rotor 38, a winding 40 or 44, and the like.

Thus, the stator 36 and / or the rotor 38 support at least one corresponding electrical conductor winding 40, 44, and the temperature (θ _s , θ _r ) of the stator and rotor is the thermal resistance R _{th - sr} , R _{th - exts} , R _{th - extr )} , each of the above methods by solving at least one equation using the heat capacity (Cs) of the stator 36 and the heat capacity (Cr) of the rotor 38. Of repetition is estimated using a digital computer.

This is disclosed in more detail in Korean Patent Laid-Open No. 10-2012-0083443, further description thereof will be omitted.

However, according to the above prior art, a separate test apparatus for measuring the thermal resistance and the heat capacity of the motor is required.

In addition, since the exact loss (ie, motor loss), heat resistance and heat capacity are unknown, the rotor temperature is inaccurate.

1. Korean Patent Publication No. 10-2012-0083443 2. Korean Patent Publication No. 10-2012-0059263 3. Korean Patent Publication No. 10-2012-0109294

The present invention has been proposed to solve the problem according to the above background, to provide a motor rotor temperature estimation device and method that can measure the thermal resistance and / or heat capacity of the motor without having a separate test device The purpose is.

It is another object of the present invention to provide an apparatus and method for estimating a motor rotor temperature capable of obtaining an accurate rotor temperature estimate without having to calculate the exact loss, heat resistance, and / or heat capacity.

The present invention provides a motor rotor temperature estimation apparatus capable of measuring the thermal resistance and / or heat capacity of the motor without having a separate test device to achieve the above problems.

The motor rotor temperature estimation device,

In the motor rotor temperature estimation device having a motor having a motor stator and a motor rotor to which the coil is wound, and an inverter for supplying power to the motor,

A motor rotor speed sensor for sensing the speed of the motor rotor;

A motor stator coil temperature sensor for sensing a coil temperature of the motor stator;

A plurality of motor stator current sensors for sensing current of the motor stator;

A back EMF calculator that calculates back EMF using the sensed current, motor stator coil temperature, and motor rotor speed; And

And a rotor temperature calculator configured to calculate a motor rotor temperature using the calculated back EMF.

The apparatus may further include a coordinate converter configured to convert the sensed current into D and Q-axis current information.

The counter electromotive force calculator may include a counter electromotive force table according to the rotor temperature, a stator resistance table according to the stator temperature, a D axis magnetic flux table according to the magnitude of the D axis current, and a D axis magnetic flux independent of temperature change. The counter electromotive force may be generated using a table.

The rotor temperature calculator may be configured to calculate the rotor temperature by using the counter electromotive force-temperature table map preset for the calculated counter electromotive force and motor stator coil temperature.

The rotor temperature calculator may not estimate the rotor temperature when the change in the Q-axis current command for driving the inverter is greater than or equal to a preset limit value.

In addition, the motor may be a permanent magnet motor using a rare earth magnet.

On the other hand, another embodiment of the present invention, the speed sensing step of sensing the speed of the motor rotor; A temperature sensing step of sensing a coil temperature of the motor stator; A current sensing step of sensing a current of the motor stator; Calculating a counter electromotive force using the sensed current, the motor stator coil temperature, and the motor rotor speed; And a rotor temperature calculating step of calculating a motor rotor temperature using the calculated back electromotive force.

In this case, the current sensing step may include a coordinate conversion step of converting the sensed current into D and Q-axis current information.

The counter electromotive force calculation step may include a counter electromotive force table according to the rotor temperature, a stator resistance table according to the stator temperature, a D-axis magnetic flux table according to the magnitude of the D-axis current, and a D-axis independent of temperature change. And generating back electromotive force using the magnetic flux table.

In the calculating of the rotor temperature, the rotor temperature may be calculated by using the counter electromotive force-temperature table map preset for the calculated back electromotive force and the motor stator coil temperature.

Further, the step of calculating the rotor temperature may include: not estimating the rotor temperature if the change in the Q-axis current command for driving the inverter is greater than or equal to a preset limit value; And estimating the rotor temperature if the change in the Q-axis current command for driving the inverter is smaller than a preset limit value.

According to the present invention, it is possible to accurately measure the rotor temperature compared to the conventional calculation method using the loss, heat resistance and heat capacity, thereby improving the motor torque control accuracy and efficiency.

In addition, another effect of the present invention is that it is not necessary to calculate the heat resistance, heat capacity, and the like, so that the implementation is easy and the process can be simplified.

In addition, another effect of the present invention is that the maximum current and time of the motor current can be used up to the allowable temperature of the rotor magnet, so that the design margin of the permanent magnet motor can be reduced, and the capacity can be reduced. It is possible.

1 is a conceptual diagram for measuring a temperature of a general motor.
FIG. 2 is a cross-sectional view of the motor shown in FIG. 1 taken along the 2-2 axis.
3 is a block diagram of a rotor temperature estimation apparatus for estimating the rotor temperature of a motor according to an embodiment of the present invention.
4 is a conceptual diagram illustrating an operating state of a temperature estimating function according to an embodiment of the present invention.
5 is a flowchart illustrating a process of creating a magnetic flux table, a counter electromotive force table, and a stator resistance table according to an embodiment of the present invention.
FIG. 6A is a graph showing a relationship of temperature VS inverse electro motive force (EMF) constants according to an embodiment of the present invention, and FIG. 6B is a diagram illustrating a concept of preparing a D-axis magnetic flux table.
7 is a flowchart illustrating a rotor temperature estimation process according to an embodiment of the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing each drawing, like reference numerals are used for like elements.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term “and / or” includes any combination of a plurality of related items or any item of a plurality of related items.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art.

Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Should not.

Hereinafter, an apparatus and method for estimating a motor rotor temperature according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram of a rotor temperature estimation apparatus for estimating the rotor temperature of a motor according to an embodiment of the present invention. Referring to FIG. 3, the rotor temperature estimating apparatus may include a motor stator coil temperature sensor 379, a motor rotor speed sensor 378, motor stator current sensors 390-1 and 390-2, a motor control unit 300, and the like. It is configured to include.

First, the motor 370 will be described. The motor 370 is a three-phase AC motor, and includes a motor stator 371 with a coil wound thereon, and a motor rotor 373. Of course, in one embodiment of the present invention is illustrated a three-phase AC motor for understanding of the description, but is not limited to this may be applied to a single-phase motor. In addition, the motor 370 may be a permanent magnet motor, but is not limited thereto and may be a universal motor.

On the stator 371 side, motor stator current sensors 390-1 and 390-2 are configured to sense a current of the motor stator 371 and provide a value to the coordinate converter 340. Of course, the motor stator current sensor is composed of a first motor stator current sensor 390-1 and a second motor stator current sensor 390-2.

In addition, the motor stator coil temperature sensor 379 and the motor rotor speed sensor 378 and the like are configured to sense the coil temperature of the motor stator 371 and the motor rotor speed.

In addition, an inverter 360 for supplying AC power to the motor 370 is configured.

The motor control unit 300 controlling the motor 370 includes a current controller 310, a pulse width modulation (PWM) generator 320, a counter electromotive force calculator 330, a coordinate converter 340, and a rotor temperature. The calculator 350 is configured.

In detail, the motor control unit 300 is connected to the motor 370 to transmit and receive a control signal and / or a sensing signal, and supply power to the inverter 360.

The current controller 310 converts the current command into a voltage command for the motor stator D / Q axis according to the D / Q axis current command and outputs it.

The pulse width modulation (PWM) generator 320 generates and applies a PWM signal for phase-converting a DC voltage to a three-phase AC voltage according to a voltage command determined and applied by the current controller 310 to the inverter 360.

Therefore, the inverter 360 is composed of a plurality of power switch elements, and supplies a current power to each phase of the motor 370 by converting the DC voltage into a three-phase AC voltage by the PWM signal applied from the PWM generator 320. do.

)를, 모터 고정자 코일 온도 센서(379)로부터 센싱된 모터 고정자 코일 온도 정보(T_s)를, 모터 회전자 속도 센서(378)로부터 센싱된 모터 회전자 속도 정보(ω_r)를 수신받아서 역기전력을 계산한다. The counter electromotive force calculator 330 senses the D / Q axis current information sensed by the motor stator current sensors 390-1 and 390-2 calculated by the coordinate converter 340.

) Receives the motor stator coil temperature information (T _s ) sensed from the motor stator coil temperature sensor 379 and the motor rotor speed information (ω _r ) sensed from the motor rotor speed sensor 378. Calculate

In other words, the counter electromotive force calculator 330 calculates the counter electromotive force using the Q-axis voltage equation and / or the D-axis magnetic flux table (current-magnetic flux table).

The rotor temperature calculator 350 calculates the rotor temperature T _r according to the counter electromotive force using a preset counter electromotive force-temperature table map.

4 is a conceptual diagram illustrating an operating state of a temperature estimating function according to an embodiment of the present invention. Referring to FIG. 4, S1 is a rotor temperature measurement OFF state.

In other words, S1 refers to a state in which the temperature of the rotor magnet is not estimated, that is, the temperature is not estimated when the change in the Q-axis current command is larger than the limit value? Iq_th.

S2 is the rotor temperature estimation ON state. In other words, it refers to a state of estimating the temperature of the rotor magnet, i.e., it is performed when the change in the Q-axis current command is smaller than the limit value? Iq_th.

5 is a flowchart illustrating a process of creating a magnetic flux table, a counter electromotive force table, and a stator resistance table according to an embodiment of the present invention. Referring to Fig. 5, a counter electromotive force table E (T _r ) corresponding to the temperature of the motor rotor 373 is created (step S500).

The counter electromotive force of a permanent magnet motor using a rare earth magnet has a characteristic of decreasing with increasing temperature. A diagram showing this is shown in FIG. 6A. 6A is a graph showing a relationship of temperature VS inverse electro-motive force (EMF) constants according to an embodiment of the present invention.

The relationship between the temperature and the counter electromotive force shown in FIG. 6A is obtained in advance through an offline experiment and then used as a formula or a table. For example, E = function (T _r ) to T _r = function (E (T _r )).

If still with reference to Figure 5, it creates a table motor stator resistance (R _s (T _s)) according to the temperature of the motor stator 371 (step S510). The motor stator resistance is characterized by an increase in temperature. Therefore, the relationship between temperature and stator resistance is also obtained in advance through an offline experiment and then used as a formula or a table. For example, R _s = function (T _s ). R _s (T _s ) reflects the stator resistance that varies with coil temperature.

Next, a D-axis magnetic flux table corresponding to the magnitude of the D-axis current is created (step S520). D axis 375 is one axis of motor rotor 373 as shown in FIG. 3.

In addition, the Q-axis voltage equation of the permanent magnet motor 370 is expressed as follows. Q axis 377 is one axis of motor rotor 373 as shown in FIG. 3.

Here, R _s represents a stator resistance, i _qs denotes a Q-axis current measurement value (or a reference value), λ _ds represents a D-axis flux value, ω _r represents a motor rotor speed.

Using Equation 1, the D-axis magnetic flux can be expressed as a function of Q-axis voltage command, Q-axis current, rotor speed, and stator coil resistance as shown in the following equation.

Here, R _s (T _s ) represents a stator resistance value that varies with coil temperature.

Stator resistance R _s is changed according to the stator coil temperature (T _s), Q-axis voltage command when it is assumed that the rotor speed and the Q-axis current stator current is constant coil temperature (T _s) and the rotor magnet temperature (T _r Is a value that depends on

Accordingly, the D-axis magnetic flux table according to the D-axis current is generated through an offline experiment based on Equation 2.

5, the D-axis magnetic flux component table irrelevant to temperature is created next (step S530).

The D-axis magnetic flux is divided into components generated by magnets (components affected by temperature) and components generated by D-axis current, and can be expressed as follows.

Where r represents the coordinates of the rotor, E represents the counter electromotive force, λ _PM represents the permanent magnet flux, and L _d represents the D-axis inductance.

Using the current-flux table obtained in the previous experiment and the counter electromotive force table (E (T _r )) according to the temperature, the magnetic flux components irrelevant to the rotor magnet temperature change are made into a table.

When performing the offline experiment, the current-magnetic flux table is prepared using Equation 2. Of course, when doing the offline experiment, make sure that T _s = T _r , that is, the stator coil temperature and the rotor temperature have similar values. Here, the counter electromotive force is a function of the rotor magnet temperature T _r .

Therefore, the D-axis magnetic flux table irrelevant to the temperature is obtained by subtracting the counter electromotive force from the D-axis magnetic flux table. This is expressed as the following equation.

That is, D-axis magnetic flux table irrespective of temperature = (D-axis magnetic flux table)-(reverse electromotive force).

Conceptually speaking, this is illustrated in FIG. 6B. That is, FIG. 6B is a diagram illustrating the concept of creating a D-axis magnetic flux table.

Thus, a current-flux table is generated that is independent of temperature changes such as

7 is a flowchart illustrating a rotor temperature estimation process according to an embodiment of the present invention. Referring to Fig. 7, it is determined whether the Q-axis current change value is smaller than the reference value (e.g.,? Iqs_th) (step S700).

If the determination result is smaller than the reference value, the counter electromotive force is calculated (step S710). This is expressed as an equation.

That is, using Equations 2 and 5, it is possible to calculate the counter electromotive force in real time as shown in Equation 6 above.

In addition, when the counter electromotive force is calculated, the rotor temperature is calculated using the back electromotive force-temperature table map preset for the counter electromotive force and the rotor temperature through an offline experiment, as shown in the following equation (step S720).

300: motor control unit
310: current controller 320: pulse width modulation (PWM) generator
330: counter electromotive force calculator 340: coordinate conversion unit
350: rotor temperature calculator 360: inverter
370: motor
371: motor stator 373: motor rotor
375: D axis 377: Q axis
378: motor rotor speed sensor
379: motor stator coil temperature sensor
390-1, 390-2: motor stator current sensor

Claims (12)

In the motor rotor temperature estimation device having a motor having a motor stator and a motor rotor to which the coil is wound, and an inverter for supplying power to the motor,
A motor rotor speed sensor for sensing the speed of the motor rotor;
A motor stator coil temperature sensor for sensing a coil temperature of the motor stator;
A plurality of motor stator current sensors for sensing current of the motor stator;
A back EMF calculator that calculates back EMF using the sensed current, motor stator coil temperature, and motor rotor speed; And
A rotor temperature calculator configured to calculate a motor rotor temperature using the calculated back EMF;
Motor rotor temperature estimation device comprising a.
The method of claim 1,
And a coordinate conversion unit for converting the sensed current into D and Q-axis current information.
The method of claim 2,
The counter electromotive force calculator includes a counter electromotive force table according to the rotor temperature, a stator resistance table according to the stator temperature, a D axis magnetic flux table according to the magnitude of the D axis current, and a D axis magnetic flux table independent of temperature change. The apparatus for estimating the temperature of a motor rotor, characterized in that to generate back electromotive force.
The method of claim 2,
And the rotor temperature calculator is configured to calculate the rotor temperature using the counter electromotive force-temperature table map preset for the calculated back electromotive force and motor stator coil temperature.
The method of claim 4, wherein
And the rotor temperature calculating unit does not estimate the rotor temperature if the change in the Q-axis current command for driving the inverter is greater than or equal to a preset limit value.
The method of claim 1,
And the motor is a permanent magnet motor using a rare earth magnet.
A speed sensing step of sensing a speed of the motor rotor;
A temperature sensing step of sensing a coil temperature of the motor stator;
A current sensing step of sensing a current of the motor stator;
Calculating a counter electromotive force using the sensed current, the motor stator coil temperature, and the motor rotor speed; And
A rotor temperature calculating step of calculating a motor rotor temperature using the calculated back EMF;
Motor rotor temperature estimation method comprising a.
The method of claim 7, wherein
The current sensing step includes a coordinate transformation step of converting the sensed current into the D and Q-axis current information.
The method of claim 8,
The counter electromotive force calculation step may include a counter electromotive force table according to the rotor temperature, a stator resistance table according to the stator temperature, a D-axis magnetic flux table according to the magnitude of the D-axis current, and a D-axis magnetic flux table irrelevant to the temperature change. Generating a counter electromotive force using the method.
The method of claim 8,
The step of calculating the rotor temperature, the motor rotor temperature estimation method, characterized in that for calculating the rotor temperature by using the back EMF-temperature table map preset for the calculated back EMF and motor stator coil temperature.
The method of claim 10,
The rotor temperature calculating step may include: estimating the rotor temperature if the change in the Q-axis current command for driving the inverter is greater than or equal to a preset limit value; And estimating the rotor temperature if the change in the Q-axis current command for driving the inverter is smaller than a preset limit value.
The method of claim 7, wherein
The motor rotor temperature estimation method, characterized in that the motor is a permanent magnet motor using a rare earth magnet.

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