JP6629017B2 - Electric motor device and electric linear actuator - Google Patents

Description

  The present invention relates to an electric motor device and an electric linear actuator, and relates to a technology for estimating a temperature for each excitation coil region in an electric motor in consideration of a temperature distribution.

The following technology has been proposed as an electric actuator using an electric motor.
1. An electric actuator that converts the rotational motion of an electric motor into a linear motion via a linear motion mechanism by depressing a brake pedal, and presses a brake pad against a brake disc to apply a braking force (Patent Document 1).
2. An electric linear motion actuator using a planetary roller screw mechanism (Patent Document 2).
3. A technology in which a thermistor is provided at a neutral terminal of each phase coil in an electric motor, and the average temperature of each phase coil is measured by the thermistor (Patent Document 3).
4. A technique for estimating a coil temperature from voltage and current and temperature characteristics of copper resistance when an electric motor is stopped (Patent Document 4).

JP-A-6-327190 JP 2006-194356 A JP-A-11-234964 JP-A-2004-208453

  In the electric actuators disclosed in Patent Literatures 1 and 2, when an abnormality occurs in the coil of the electric motor, there is a possibility that the braking function is reduced. This electric motor has a very limited mounting space for the vehicle, and an increase in the unsprung weight of the vehicle due to an increase in the size of the electric motor causes a problem that the riding comfort of the occupant is deteriorated. Therefore, it may be difficult to reduce the heat loss by reducing the copper loss of the motor coil.

In order to avoid the above situation, it is necessary to control the temperature of the motor coil, and therefore, it is necessary to accurately estimate the motor coil temperature. For example, there is a method of estimating the motor coil temperature using the temperature dependence of the resistance value of copper as disclosed in Patent Document 4.
However, in the above case, since the resistance value includes not only the coil but also a contact resistance and a control element such as an FET, it may be difficult to precisely model the temperature dependence. Further, for example, when a follow-up operation to an arbitrary input is required as in the case of an electric brake, it may be difficult to guarantee that a static condition that is not affected by transient response such as inductance is reliably provided. .

As a method that is not affected by the above transient response, for example, a countermeasure such as that disclosed in Patent Document 3 in which a temperature-sensitive element such as a thermistor is disposed in a motor coil is generally used.
However, for example, when heat generation is relatively quicker than heat transfer, such as when a suddenly large torque is exerted, a temperature distribution may occur in which a portion of the excitation coil that is difficult to dissipate heat locally. At this time, when the temperature sensing element is disposed at the coil end portion or the coil surface layer as in Patent Document 3, the coil may be abnormal due to the thermal load, or the thermal load may be insufficient in consideration of the temperature distribution. Under certain conditions, the system may stop. However, it is difficult to provide a temperature-sensitive resistor so that the temperature of the entire coil can be observed as the above countermeasure, which may cause problems in terms of cost and mounting space.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electric motor device and an electric linear actuator which can reduce the cost and solve the problem of the mounting space, and can accurately perform temperature estimation in consideration of the temperature distribution of the exciting coil. is there.

An electric motor device Ms of the present invention is an electric motor device including an electric motor 4 and a control device 2 for controlling the electric motor 4,
A temperature detecting element 26 for detecting the temperature of the exciting coil 4a is provided on the exciting coil 4a of the electric motor 4,
The control device 2 includes:
Current detection means 22 for obtaining a current flowing through the exciting coil 4a;
For a plurality of regions in the exciting coil 4a, a plurality of regions in the exciting coil 4a are determined based on a current of the exciting coil 4a obtained by the current detecting means 22 and information including heat generation and heat radiation characteristics in the exciting coil 4a. Coil temperature estimating means 19 for calculating the estimated temperature of the region,
The temperature of the exciting coil 4a detected by the temperature detecting element 26 and the estimated temperature of the area closest to the temperature detecting element 26 among the estimated temperatures of the plurality of areas estimated by the coil temperature estimating means 19. And a temperature distribution or the like estimating means 20 for estimating a temperature distribution in a plurality of regions or a local maximum temperature in the excitation coil 4a based on a comparison result with the above.
The “plurality of regions” refers to the excitation coil 4a wound in a plurality of layers around a predetermined tooth 28a provided with the temperature detecting element 26, and the wound excitation coil 4a is perpendicular to the motor center axis. In a cross section viewed by cutting on a plane, for example, it indicates a plurality of layers of coil regions having different distances relative to the outer surface of the teeth 28a. In addition, the method of dividing the plurality of regions is appropriately set by a designer according to each specification such as a coil winding.

  According to this configuration, the current detecting means 22 obtains a current flowing through the exciting coil 4a. The coil temperature estimating means 19 calculates the estimated temperatures of a plurality of regions in the exciting coil 4a from the obtained current of the exciting coil 4a and information including heat generation and heat radiation characteristics of the exciting coil 4a. The temperature distribution or the like estimating means 20 determines the temperature of the exciting coil 4 a detected by the temperature detecting element 26 and the position closest to the temperature detecting element 26 among the estimated temperatures of the plurality of regions estimated by the coil temperature estimating means 19. Compare with the estimated temperature of the area. The temperature distribution etc. estimating means 20 estimates the temperature distribution or the local maximum temperature in a plurality of regions in the exciting coil 4a based on the comparison result.

  By the way, when the heat generation is relatively quicker than the heat transfer, such as when a suddenly large torque is exerted, a temperature distribution may occur in which a portion of the excitation coil that is difficult to dissipate heat locally. Even in such a case, the temperature distribution or the like estimating means 20 estimates the temperature distribution and the local maximum temperature of a plurality of regions in the exciting coil 4a based on the comparison result without observing the temperature of the entire coil. can do. Therefore, in comparison with the technique of observing the temperature of the entire coil, this configuration suffices to provide the temperature detecting element 26 on at least one exciting coil 4a, so that cost can be reduced and the problem of mounting space can be solved. . Further, it is possible to accurately perform temperature estimation in consideration of the temperature distribution of the exciting coil 4a.

The motor stator 27 of the electric motor 4 includes a ring-shaped stator core 28 and a plurality of the exciting coils 4a wound around respective teeth 28a which are formed in a plurality on the peripheral surface of the stator core 28 and project in the radial direction. Have
The plurality of regions in the excitation coil 4a include:
With respect to the excitation coil 4a which is provided with the temperature detecting element 26 and is wound in a plurality of layers around a predetermined tooth 28a, the predetermined tooth 28a is used as a reference.
A proximity region Ka of a layer closest to the outer surface of the tooth 28a;
A separation region Ra of a layer most separated from the outer surface of the tooth 28a;
An intermediate region Ta between the proximity region Ka and the separation region Ra may be included.
The determined teeth 28a are appropriately determined in consideration of, for example, the number of assembly steps for providing the temperature detecting element 26 on the exciting coil 4a.

  In this case, heat radiation from the excitation coil 4a in the proximity region Ka of the layer closest to the outer surface of the teeth 28a to the stay core portion 28 is the main heat radiation. In addition, heat conduction occurs between the contact areas according to the temperature difference. In addition, heat is radiated from, for example, air into the air from the excitation coil 4a located in the separation area Ra of the most distant layer. Since the temperature distribution is likely to occur due to the inner and outer circumferences with respect to the outer surface of the tooth 28a, the plurality of regions are divided into the proximity region Ka, the separation region Ra, the intermediate region Ta, and the outer surface of the tooth 28a as described above. It is preferable to divide into

The coil temperature estimating unit 19 sets a value proportional to the square of the current of the exciting coil 4a obtained by the current detecting unit 22 as an operation amount, and sets a state amount and an observed amount as estimated temperatures of the exciting coil 4a in each region, the state transition matrix and heat capacity and thermal conductivity of the exciting coil 4a of each region, prior Symbol controller 2, the state estimation observer including the coil temperature estimating means 19 and the temperature distribution, etc. estimator 20 29 may be included.
The determined gain is determined by, for example, a result of a test, a simulation, or the like. This gain may be a fixed value or a variable value.

It said state estimation observer 29, may have a function of gain of the feedback with a correlation that is defined for the change in the manipulated variable is changed.
The determined correlation is determined by, for example, a result of a test, a simulation, or the like.
In general, the larger the gain L, the better the convergence speed. Therefore, for example, a process for increasing the gain L when a large current is applied where the coil temperature tends to change sharply may be inserted. By changing the gain L in this way, the estimated temperature of the exciting coil 4a can be corrected quickly and finely.

The control device 2 has determined that the maximum temperature estimated by the temperature distribution etc. estimating means 20 and a value obtained by using at least one of the differential values thereof have become equal to or greater than a predetermined value. At this time, a phase current limiting means 24 for limiting a phase current of the exciting coil 4a whose maximum temperature is estimated may be provided.
The determined value is determined based on a result of a test, a simulation, or the like, for example.

  According to this configuration, the phase current limiting unit 24 determines this value with respect to the maximum temperature estimated by the temperature distribution or the like estimating unit 20 and a value using at least one of its differential values. It is determined whether the value is equal to or greater than the value. When it is determined that the maximum temperature has been reached, the phase current of the exciting coil 4a whose maximum temperature has been estimated is limited. Therefore, by limiting the phase current of the excitation coil 4a when a load is concentrated on the predetermined excitation coil 4a, it is possible to reliably prevent the excitation coil 4a from being thermally degraded.

The electric linear motion actuator 1 of the present invention includes any one of the electric motor devices Ms of the present invention, and a linear motion mechanism 6 that converts a rotational motion of the electric motor 4 of the electric motor device Ms into a linear motion. The control device 2 controls the electric motor . When the control device 2 controls the axial force of the linear motion mechanism 6 to be kept constant, for example, the motor phase current is constantly applied constantly. For this reason, the loss of each excitation coil 4a varies, and each excitation coil 4a has a temperature difference from each other. Even if a temperature difference occurs between the respective excitation coils 4a, measures to reliably prevent thermal deterioration of the excitation coils 4a should be taken by improving the temperature detection accuracy of all the excitation coils 4a. Can be.

  An electric motor device according to the present invention is an electric motor device including an electric motor and a control device that controls the electric motor, wherein an exciting coil of the electric motor is provided with a temperature detecting element that detects a temperature of the exciting coil. The control device includes: a current detection unit that obtains a current flowing through the excitation coil; a plurality of regions in the excitation coil; a current of the excitation coil obtained by the current detection unit; Coil temperature estimating means for calculating estimated temperatures of a plurality of regions in the exciting coil from information including heat radiation characteristics, the temperature of the exciting coil detected by the temperature detecting element, and the coil temperature estimating means Comparison between the estimated temperature of the plurality of regions and the estimated temperature of the region closest to the temperature detecting element Based on the results, having a temperature distribution such as estimating means for estimating the temperature distribution or local maximum temperatures of a plurality of regions in the exciting coil. Therefore, it is possible to reduce the cost and solve the problem of the mounting space, and it is possible to accurately perform the temperature estimation in consideration of the temperature distribution of the exciting coil.

FIG. 2 is a block diagram of a control system of the electric linear actuator according to the embodiment of the present invention. It is a figure which shows the same electric linear motion actuator schematically. It is sectional drawing of the motor stator of the electric motor of the same electric linear motion actuator. FIG. 4 is an enlarged view of a portion A in FIG. 3. It is a conceptual diagram of the temperature rise of each area | region when a predetermined motor torque is exhibited by the electric linear actuator. It is a figure showing an example of 1 composition of a coil temperature estimator and an estimation error amendment device of the electric linear actuator.

An electric motor system including an electric motor device according to an embodiment of the present invention will be described with reference to FIGS. In this embodiment, an example is shown in which the electric motor device is applied to an electric linear motion actuator for a vehicle, but the present invention is not limited to this example.
As shown in FIG. 1, this electric motor system includes a plurality of electric linear actuators 1 provided for each wheel of the vehicle, a power supply device 3, and a host ECU 17. Each electric linear actuator 1 includes an electric motor device Ms, a speed reduction mechanism 5, and a linear motion mechanism 6. The electric motor device Ms includes the electric motor 4 and the control device 2. In this embodiment, an electric brake actuator Da including the electric motor 4, the speed reduction mechanism 5, and the linear motion mechanism 6 is configured. First, the electric brake actuator Da will be described.

  As shown in FIG. 2, the electric brake actuator Da includes an electric motor 4, a reduction mechanism 5 for reducing the rotation of the electric motor 4, a linear motion mechanism 6, a parking brake mechanism 7 serving as a parking brake, and a brake rotor. 8 and a friction member 9. The electric motor 4, the speed reduction mechanism 5, and the linear motion mechanism 6 are incorporated in, for example, a housing or the like (not shown). The electric motor 4 comprises a three-phase synchronous motor or the like.

  The reduction mechanism 5 is a mechanism that transmits the rotation of the electric motor 4 to the tertiary gear 11 fixed to the rotating shaft 10 at a reduced speed, and includes a primary gear 12, an intermediate gear 13, and a tertiary gear 11. In this example, the reduction mechanism 5 reduces the rotation of the primary gear 12 attached to the rotor shaft 4 a of the electric motor 4 by the intermediate gear 13, and reduces the rotation of the tertiary gear 11 fixed to the end of the rotation shaft 10. It can be transmitted to.

  The linear motion mechanism 6 serving as a friction member operating means converts the rotational motion output from the speed reduction mechanism 5 into a linear motion of the linear motion portion 14 by a feed screw mechanism, and brings the friction member 9 into contact with the brake rotor 8. It is a mechanism for separating. The translation portion 14 is supported so as not to rotate and to be movable in the axial direction indicated by an arrow A1. A friction member 9 is provided at an end of the direct acting portion 14 on the outboard side. By transmitting the rotation of the electric motor 4 to the linear motion mechanism 6 via the speed reduction mechanism 5, the rotational motion is converted into a linear motion, and this is converted into a pressing force of the friction member 9, whereby the linear motion mechanism 6 is transmitted. To generate a braking force which is an axial force of the vehicle. When the electric brake actuator Da is mounted on a vehicle, the outside of the vehicle is called an outboard side, and the center side of the vehicle is called an inboard side.

  As the actuator 16 of the parking brake mechanism 7, for example, a linear solenoid is applied. The lock member (solenoid pin) 15 is advanced by the actuator 16 and fitted into a locking hole (not shown) formed in the intermediate gear 13 to lock the lock, thereby preventing the rotation of the intermediate gear 13. , Put the parking lock. By releasing the lock member 15 from the locking hole, the rotation of the intermediate gear 13 is allowed, and the unlocked state is set.

  As shown in FIG. 1, the control device 2 of each electric motor device Ms is connected to a power supply device 3 and a host ECU 17 that is a host control unit of each control device 2. In FIG. 1, only one electric linear actuator 1 is shown, and illustration of the other electric linear actuators is omitted. As the host ECU 17, for example, an electric control unit that controls the entire vehicle is applied. Further, the host ECU 17 has an integrated control function of each electric motor device Ms. A target value command such as a motor angular velocity, a motor angle, a torque, and other predetermined loads is input from the host ECU 17 to the control calculator 18 of the control device 2.

The power supply device 3 supplies electric power to the electric motor 4 and the control device 2 in each electric motor device Ms.
The control device 2 includes a control calculator 18, a coil temperature estimator 19 as a coil temperature estimator, an estimation error corrector 20 as a temperature distribution or the like estimator, a motor driver 21, and a current sensor 22 as a current detector. Having. The control calculator 18, the coil temperature estimator 19, and the estimation error corrector 20 may be implemented by, for example, a processor such as a microcomputer or a hardware module such as an ASIC, an FPGA, or a DSP.

  The control calculator 18 has a control calculation function unit 23 and a phase current limiting unit 24. The control calculation function unit 23 generates a control signal of the motor driver 21 from the values of the various sensors so that the control target from the host ECU 17 is achieved. At this time, the phase current limiting unit 24 refers to the estimation result of the coil temperature estimator 19 and executes a process of protecting the exciting coil 4a from heat generation according to the estimation result (described later).

  The motor driver 21 converts the DC power of the power supply device 3 into three-phase AC power used for driving the electric motor 4. The motor driver 21 may constitute, for example, a half-bridge circuit using a switching element such as a MOSFET. Further, the motor driver 21 may include a pre-driver that drives the switch element instantaneously.

  The current sensor 22 is a current detection unit that obtains a current flowing through the three-phase excitation coil 4a. The current sensor 22 is one of the various sensors, and may be, for example, a current sensor that detects a magnetic field generated around a power transmission path, and detects a voltage drop amount using a shunt resistor and an operation amplifier. A current sensor may be used. When a current sensor for detecting the magnetic field is used, the current sensor can be mounted at high efficiency and high accuracy, and at a low cost when a current sensor for detecting the amount of voltage drop is used. Further, in measuring the three-phase current, for example, the current may be measured only in any two of the three phases, and the remaining one phase may be obtained by using a characteristic in which the sum of the three-phase currents is zero.

  The electric motor 4 is a brushless DC motor including an exciting coil 4a, a rotor angle sensor 25, a temperature sensor 26, and a rotor (not shown) having a permanent magnet. Is preferred. However, as the electric motor 4, a DC motor with a brush or a stepping motor can also be used functionally. The excitation coil 4a may be a concentrated winding wound around one tooth in a concentrated manner, or a distributed winding extending over a plurality of teeth. Comparing the two, the concentrated winding can be downsized, and the distributed winding can have high efficiency and high output.

  FIG. 3 is a sectional view of the motor stator 27 of the electric motor 4. The motor stator 27 has, for example, a stator core 28 made of a soft magnetic material and the exciting coil 4a. The stator core portion 28 has a ring shape with an outer peripheral surface having a circular cross section, and has a plurality of teeth 28a protruding toward the inner diameter side formed on the inner peripheral surface thereof arranged in the circumferential direction. The excitation coil 4a is wound around each tooth 28a of the stator core 28.

  FIG. 4 is a partially enlarged view showing a portion A in FIG. 3 in an enlarged manner. As shown in FIGS. 3 and 4A, the temperature sensor 26 as a temperature detecting element detects the temperature of the exciting coil 4a. One of the three-phase excitation coils 4a of the electric motor 4 is provided with a temperature sensor 26 for detecting the temperature of the excitation coil 4a. It is preferable to use a thermistor using a temperature-sensitive resistor and a voltage dividing circuit as the temperature sensor 26 at a simple and low cost.

  In this example, the temperature sensor 26 is disposed in the gap δ between the exciting coils 4a, 4a adjacent to each other in the circumferential direction between the teeth 28a, 28a adjacent in the circumferential direction. The temperature sensor 26 is disposed so as to be in contact with the outer peripheral surface of the separation region Ra of the layer most separated from the outer surface of the teeth 28a among a plurality of regions (described later) in one of the excitation coils 4a. Note that the exciting coils 4a, 4a adjacent to each other may be covered with a mold material (not shown) together with the temperature sensor 26.

  As shown in FIG. 1, for example, a sensor such as a resolver or a magnetic encoder may be mounted on the electric motor 4 as the rotor angle sensor 25, and the rotor angle is estimated using a rotating coil voltage in a so-called sensorless manner. You may. When a sensor such as a magnetic encoder is used, the rotor angle can be detected with high accuracy from a low speed to a stopped state, and when the rotor angle is estimated without a sensor, it is advantageous in saving space.

  In this embodiment, in particular, the control device 2 is provided with a coil temperature estimator 19 and an estimation error corrector 20. Further, a phase current limiting means 24 is provided in the control calculator 18. The coil temperature estimator 19 divides the exciting coil 4a into a plurality of regions, and performs temperature estimation for each region. FIG. 4A shows an example in which the exciting coil 4a is divided into a plurality of regions Ra, Ka, and Ta. For reasons described below, the temperature distribution is likely to occur due to the inner and outer circumferences of the teeth 28a of the stator core portion 28, and thus it is considered that the area division as shown in FIG.

The plurality of regions include a proximity region Ka, a separation region Ra, and an intermediate region Ta.
The proximity region Ka is formed of a layer closest to the outer surface of the teeth 28a with respect to the teeth 28a around which the exciting coils 4a are wound, with respect to the exciting coils 4a wound around a plurality of layers on which the temperature sensors 26 are provided. An annular area. The separation area Ra is an annular area made of a layer most separated from the teeth 28a. The intermediate region Ta is an annular region composed of a layer between the proximity region Ka and the separation region Ra.

  FIG. 4B shows an example of a heat radiation path when the exciting coil 4a generates heat. In this example, the heat radiation from the coil 4aa in the proximity area Ka closest to the outer surface of the tooth 28a to the stator core 28 is the main heat radiation, and heat conduction occurs according to the temperature difference between the respective contact areas. The heat is radiated into the air from the separated area Ra. As another example, when the exciting coil 4a is molded with a molding material (not shown), a contact portion with the molding material serves as a heat radiation element. In addition, the method of dividing the plurality of regions is appropriately set by a designer according to each specification such as a coil winding.

  FIG. 5 is a conceptual diagram of a temperature rise in each region when a predetermined motor torque is exerted by the electric linear actuator. At an arbitrary time during which a predetermined motor torque is exerted, the intermediate region Ta of the exciting coil 4a (FIG. 4) has a higher temperature than the adjacent region Ka and the separated region Ra has an intermediate temperature due to the above-described heat radiation and heat conduction. The temperature is higher than in the region Ta.

  As shown in FIG. 1, the coil temperature estimator 19 includes, for the plurality of regions in the excitation coil 4a, the current of the excitation coil 4a obtained by the current sensor 26 and the heat generation and heat radiation characteristics of the excitation coil 4a. From the information, the estimated temperatures of the plurality of regions in the exciting coil 4a are calculated. The coil temperature estimator 19 includes a plurality of partial area estimators 19a, and these partial area estimators 19a calculate the estimated temperatures of the plurality of areas, respectively.

Here, FIG. 6 is a diagram showing one configuration example of the coil temperature estimator 19 and the estimation error corrector 20 of the electric linear actuator. As shown in FIGS. 1 and 6, the control device 2 includes a linear state estimation observer 29 including a coil temperature estimator 19 and an estimation error corrector 20.
The coil temperature estimator 19 is given, for example, as a general heat transfer characteristic based on the following heat generation and heat radiation characteristics.
[Temperature change amount] = [Heat amount] / [Heat capacity]
= ([Temperature difference from peripheral part] x [Heat transfer coefficient] + [Heat generation]) ÷ [Heat capacity]

  In the above formula, the heat capacity mainly consists of the specific heat and the volume of the substance. The heat transfer coefficient includes the heat conductivity of the substance, the heat transfer coefficient of the contact portion, the heat transfer area, the heat transfer distance, and the like. Heat generation mainly consists of coil copper loss. The heat radiation includes, for example, a temperature difference between the stator core and an insulator (not shown) and a heat transfer coefficient of a contact portion.

  As described above, in the coil temperature estimator 19, the state quantity is used as the estimated temperature of the excitation coil 4a in each of the regions Ra, Ka, and Ta, and the input operation amount is generated in each of the regions Ra, Ka, and Ta proportional to the square of the current. And the state transition matrix is the heat capacity and heat transfer coefficient of the exciting coil 4a in each of the regions Ra, Ka, and Ta. The current is provided from a current sensor 22. The heat transfer coefficient includes a heat transfer coefficient between the separation area Ra and the intermediate area Ta, and a heat transfer coefficient between the intermediate area Ta and the adjacent area Ka.

Meanwhile coil temperature of a region Ra in which a temperature sensor 26, because it directly detected at the same temperature sensor 26, need not be estimated by the coil temperature estimator 19. However, in some cases, such as when a simple measuring system composed of a temperature-sensitive resistor and a divided circuit is constructed, it is easily affected by noise. In such a case, since the coil temperature estimator 19 of the present embodiment plays the role of a filter, it is preferable to perform the estimation by the coil temperature estimator 19 as in the other regions Ta and Ka.

  The observer gain L of the state estimation observer 29 may be a fixed value, or may be a variable value that changes with a predetermined correlation with the change in the operation amount (the amount of heat generated in each area). Generally, the higher the gain, the better the convergence speed. Therefore, for example, a process for increasing the gain L at the time of applying a large current in which the coil temperature is likely to change sharply may be inserted. By changing the gain L in this way, the estimated temperature of the exciting coil 4a can be corrected quickly and finely.

  The estimation error corrector 20 determines the temperature of the excitation coil 4a detected by the temperature sensor 26 and the area (Ra, Ka, Ta) estimated by the coil temperature estimator 19 that is closest to the temperature sensor 26 among the areas Ra, Ka, and Ta. In this example, the estimated temperatures of the regions Ra, Ka, and Ta estimated by the coil temperature estimator 19 are corrected based on the comparison result with the estimated temperature of the separation region Ra). The estimation error corrector 20 can be implemented, for example, as a correction function for the next step state quantity in the differential state equation or a correction function for the state quantity differential value in the continuous approximation state equation.

  As described above, by configuring the coil temperature estimator 19 and the estimation error corrector 20, it is possible to estimate the coil temperatures of the respective regions Ra, Ka, and Ta in the exciting coil 4a. From the estimated coil temperatures of the regions Ra, Ka, and Ta, the temperature distribution and the local maximum temperature of the plurality of regions Ra, Ka, and Ta in the exciting coil 4a can be obtained. Note that the sign of the addition / subtraction operation unit in FIG. 6 is set in accordance with the mathematical expression development at the time of mounting.

  As shown in FIG. 1, the phase current limiting unit 24 has a determining unit 24a and a limiting unit 24b. The determination unit 24a determines the maximum temperature of the estimated temperature of each of the regions Ra, Ka, and Ta corrected by the estimation error corrector 20 and a value using at least one of its differential values. It is determined whether the value is equal to or greater than the set value. When it is determined that the temperature has become equal to or greater than the value determined by the determining unit 24a, the limiting unit 24b limits the phase current of the exciting coil 4a at which the maximum temperature of the estimated temperature is estimated.

  In this case, for example, the limiting unit 24b may limit the estimated phase current so as to reduce a few% to several tens% of the estimated phase current, or according to one or both of the motor rotation speed and the coil estimated temperature. Thus, the current may be limited to a predetermined phase current. The determined phase current is determined by, for example, a result of a test, a simulation, or the like. Therefore, by limiting the phase current of the excitation coil 4a when a load is concentrated on the predetermined excitation coil 4a, it is possible to reliably prevent the excitation coil 4a from being thermally degraded.

  According to the electric motor system described above, when the heat generation such as when suddenly exerting a large torque is relatively faster than the heat transfer, the temperature distribution at which the heat-dissipating portion in the exciting coil locally generates heat is generated. Can occur. Even in such a case, the estimation error corrector 20 detects the temperature of the exciting coil 4a detected and the regions Ra, Ka, Ta estimated by the coil temperature estimator 19 without observing the temperature of the entire coil. It is possible to estimate the temperature distribution and the local maximum temperature of the plurality of regions Ra, Ka, and Ta in the exciting coil 4a based on the result of comparison with the estimated temperature of the region Ra closest to the temperature sensor 26 among the estimated temperatures. it can.

Therefore, in contrast to the technique of observing the temperature of the entire coil, this configuration suffices to provide the temperature sensor 26 on at least one of the exciting coils 4a, so that the cost can be reduced and the mounting space problem can be solved. Further, it is possible to accurately perform temperature estimation in consideration of the temperature distribution of the exciting coil 4a. Therefore, it is possible to improve the temperature detection accuracy when a particularly large current flows in a concentrated manner.
By improving the temperature detection accuracy, it is possible to reliably prevent an abnormality caused by the heat of the exciting coil 4a. This makes it possible to increase the degree of freedom in design.

The temperature sensor 26 may be arranged on the inner peripheral surface of the proximity area Ka in the exciting coil 4a. In this case, for example, a concave portion may be provided on the outer peripheral surface of the tooth 28a, and the temperature sensor 26 may be provided in the concave portion.
Instead of the state estimation observer 29, for example, a non-linear observer represented by a VSS observer may be used. By using such a non-linear observer, the accuracy of removing error factors is improved.

  The electric motor device Ms of the present embodiment may be applied to an electric press. When the pressing force of the electric press is maintained at a constant value, the motor current continues to be applied at a constant value, so that a temperature difference occurs in each region of the exciting coil 4a. By providing the error corrector 20, the coil temperature of each region of the exciting coil 4a can be accurately obtained.

  Although the embodiments for carrying out the present invention have been described based on the embodiments, the embodiments disclosed herein are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Electric linear motion actuator 2 ... Control device 4 ... Electric motor 6 ... Linear motion mechanism 4a ... Exciting coil 19 ... Coil temperature estimator (coil temperature estimation means)
20: Estimation error corrector (temperature distribution and other estimation means)
22 ... Current sensor (current detection means)
24 phase current limiting means 26 temperature sensor (temperature detecting element)
27 motor stator 28 stator core 28a teeth Ms electric motor device

Claims (6)

In an electric motor device including an electric motor and a control device that controls the electric motor,
A temperature detecting element for detecting a temperature of the exciting coil is provided on the exciting coil in the electric motor,
The control device includes:
Current detection means for obtaining a current flowing through the exciting coil;
For a plurality of regions in the excitation coil, the estimated temperatures of the plurality of regions in the excitation coil are calculated from the current of the excitation coil obtained by the current detection unit and information including heat generation and heat radiation characteristics in the excitation coil. Coil temperature estimating means for calculating each,
A comparison result between the temperature of the exciting coil detected by the temperature detecting element and an estimated temperature of an area closest to the temperature detecting element among the estimated temperatures of the plurality of areas estimated by the coil temperature estimating means. And a temperature distribution or the like estimating means for estimating a temperature distribution or a local maximum temperature of a plurality of regions in the excitation coil based on the electric motor. 2. The electric motor device according to claim 1, wherein the motor stator of the electric motor is wound around a ring-shaped stator core portion and a plurality of teeth that are formed side by side on the peripheral surface of the stator core portion and project radially. Having the exciting coil,
A plurality of regions in the excitation coil,
The temperature detecting element is provided, with respect to the excitation coil wound in a plurality of layers on a predetermined tooth, based on the predetermined tooth,
A proximity region of the layer closest to the outer surface of the teeth,
A separation region of the layer most separated from the outer surface of the teeth,
An electric motor device including an intermediate region between the proximity region and the separation region. 3. The electric motor device according to claim 1, wherein the coil temperature estimating unit uses a value proportional to a square of a current of the exciting coil obtained by the current detecting unit as an operation amount, and a state amount and an observation amount. was the estimated temperature of the exciting coil of each region, the state transition matrix and the heat capacity and thermal conductivity of the exciting coil of each region, prior Symbol controller the coil temperature estimating unit and the temperature distribution and the like estimating means An electric motor device including a state estimation observer. The electric motor according to claim 3, wherein the state estimation observer, the electric motor apparatus having a function of gain of the feedback with a correlation that is defined for the change in the manipulated variable is changed.   5. The electric motor device according to claim 1, wherein the control device is configured to control at least one of the maximum temperature estimated by the temperature distribution or the like estimation unit, and a differential value thereof. 6. An electric motor device having phase current limiting means for limiting the phase current of the exciting coil whose maximum temperature is estimated when this value becomes equal to or greater than a predetermined value. Comprising an electric motor apparatus according to any one of claims 1 to 5, and a linear motion mechanism for converting the linear motion to rotational motion of the electric motor of the electric motor device, the control device, the electric An electric linear actuator that controls the motor.

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