JP2017058131A - Electric motor device, and electromotive direct acting actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor device and an electromotive direct acting actuator that can help reduce costs, solve the problem of mounting space and accurately estimate temperature by taking the temperature distribution of an exciting coil into account.SOLUTION: A controller 2 comprises a current sensor 22 that finds a current to be let flow to an exciting coil 4a and a coil temperature estimator 19 that calculates estimated temperatures of multiple areas in the exciting coil 4a from information regarding the current of the exciting coil 4a and heat generating and heat radiation characteristics of the exciting coil 4a. The controller further has an estimation error corrector 20 that estimates temperature distribution in the multiple areas or the maximum local temperature in the exciting coil 4a on the basis of the result of comparison between the temperature of the exciting coil 4a detected by a temperature sensor 26 and the estimated temperature of the area closest in position to the temperature sensor 26 out of the temperatures in the multiple areas estimated by the coil temperature estimator 19.SELECTED DRAWING: Figure 1

Description

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

The following techniques have been proposed as an electric actuator using an electric motor.
1. An electric actuator that converts a 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 disk to apply a braking force (Patent Document 1).
2. An electric linear actuator using a planetary roller screw mechanism (Patent Document 2).
3. A technique in which a thermistor is provided at the neutral point terminal of each phase coil in the electric motor, and the average temperature of each phase coil is measured by this thermistor (Patent Document 3).
4). A technique for estimating a coil temperature from voltage, current, and temperature characteristics of copper resistance when the electric motor is in a stopped state (Patent Document 4).

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

  In the electric actuators such as Patent Documents 1 and 2, if an abnormality occurs in the coil of the electric motor, the brake function may be lowered. This electric motor has a very limited mounting space with respect to 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 ride comfort of the passenger is deteriorated. For this reason, 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, the temperature management of the motor coil is required, and for that purpose, it is necessary to estimate the motor coil temperature with high accuracy. For example, there is a method of estimating the motor coil temperature using the temperature dependence characteristic of the resistance value of copper as shown in Patent Document 4.
However, in the above case, since the resistance value includes not only the coil but also a control element such as a contact resistance or an FET, it may be difficult to strictly model temperature dependence. Further, for example, when a follow-up operation for an arbitrary input is required, such as an electric brake, it may be difficult to ensure that a static condition that is not affected by a transient response such as an inductance is reliably provided. .

As a technique that is not affected by the transient response, for example, a countermeasure for disposing a temperature sensitive element such as a thermistor on a motor coil as shown in Patent Document 3 is generally used.
However, for example, in the case where heat generation is relatively faster than heat transfer, such as when a large torque is suddenly exerted, there may be a temperature distribution in which portions of the exciting coil that are difficult to dissipate heat locally. At this time, when the temperature sensitive element is arranged at the coil end portion or the coil surface layer as in Patent Document 3, the coil is abnormal due to the thermal load, or the thermal load is considered in consideration of the temperature distribution. The system may stop in some state. 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, and there is a possibility that a problem may occur in terms of cost and mounting space.

  An object of the present invention is to provide an electric motor device and an electric linear actuator that can reduce the cost and solve the mounting space problem and can accurately estimate the temperature in consideration of the temperature distribution of the exciting coil. is there.

An electric motor device Ms according to the present invention includes an electric motor 4 and a control device 2 that controls the electric motor 4.
The exciting coil 4a in the electric motor 4 is provided with a temperature detecting element 26 for detecting the temperature of the exciting coil 4a.
The control device 2
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 currents in the exciting coil 4a are obtained from the current of the exciting coil 4a obtained by the current detecting means 22 and information including heat generation and heat dissipation characteristics in the exciting coil 4a. Coil temperature estimating means 19 for calculating the estimated temperature of each region;
The temperature of the exciting coil 4a detected by the temperature detecting element 26 and the estimated temperature of the region closest to the temperature detecting element 26 among the estimated temperatures of the plurality of regions estimated by the coil temperature estimating means 19 And temperature distribution estimation means 20 for estimating a temperature distribution of a plurality of regions or a local maximum temperature in the exciting coil 4a based on the 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 in which the temperature detection element 26 is provided, and the wound excitation coil 4a is perpendicular to the motor central axis. In a cross section viewed by cutting along a plane, for example, it refers to a multi-layered coil region whose distance is relatively different from the outer surface of the tooth 28a. In addition, how to divide the plurality of regions is set as appropriate by the designer according to each specification such as coil winding.

  According to this configuration, the current detection means 22 obtains a current flowing through the exciting coil 4a. The coil temperature estimating means 19 calculates 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 dissipation characteristics in the exciting coil 4a. The temperature distribution etc. estimating means 20 is closest to the temperature detecting element 26 among the temperature of the exciting coil 4a detected by the temperature detecting element 26 and the estimated temperatures of the plurality of regions estimated by the coil temperature estimating means 19. Compare with the estimated temperature of the area. Based on the comparison result, the temperature distribution etc. estimating means 20 estimates the temperature distribution or the local maximum temperature of a plurality of regions in the exciting coil 4a.

  By the way, in the case where heat generation is relatively quicker than heat transfer, such as when a large torque is suddenly exerted, a temperature distribution in which a portion in the exciting coil that is difficult to dissipate heat locally may occur. Even in such a case, the temperature distribution etc. estimation means 20 estimates the temperature distribution and 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 contrast to the technique of observing the temperature of the entire coil, this configuration is sufficient if the temperature detecting element 26 is provided in at least one exciting coil 4a, so that the cost can be reduced and the problem of mounting space can be solved. . In addition, temperature estimation considering the temperature distribution of the exciting coil 4a can be performed with high accuracy.

The motor stator 27 in the electric motor 4 includes a ring-shaped stator core portion 28 and the excitation coil 4a wound around each of the teeth 28a that are formed side by side on the circumferential surface of the stator core portion 28 and project in the radial direction. Have
The plurality of regions in the exciting coil 4a are:
The excitation coil 4a wound in a plurality of layers on a predetermined tooth 28a provided with the temperature detection element 26, with the predetermined tooth 28a as a reference,
A proximity region Ka of the layer closest to the outer surface of the tooth 28a;
A separation region Ra of a layer farthest from the outer surface of the tooth 28a;
It may include an intermediate region Ta between the proximity region Ka and the separation region Ra.
The predetermined teeth 28a are determined as appropriate in consideration of, for example, the number of assembly steps for providing the temperature detecting element 26 in the exciting coil 4a.

  In this case, heat radiation from the exciting coil 4a in the proximity region Ka of the layer closest to the outer surface of the tooth 28a to the stay core portion 28 is the main heat radiation. Moreover, heat conduction according to the temperature difference occurs between the contact regions. In addition, heat is radiated, for example, into the air from the excitation coil 4a in the separation region Ra of the most separated layer. Since the temperature distribution tends 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 adjacent region Ka, the separation region Ra, and the intermediate region Ta with respect to the outer surface of the tooth 28a as described above. It is preferable to divide into two.

The coil temperature estimation means 19 uses a value proportional to the square of the current of the excitation coil 4a obtained by the current detection means 22 as an operation amount, and uses a state quantity and an observation quantity as an estimated temperature of the excitation coil 4a in each region, The state transition matrix is defined as the heat capacity of the exciting coil 4a in each region, the thermal conductivity, the heat transfer coefficient between the regions, and the amount of heat released to external elements. The temperature distribution estimation means 20 is detected by the temperature detection element 26. The control device 2 includes a feedback of a value obtained by multiplying the deviation between the temperature of the exciting coil 4a and the observed quantity by a gain determined, and the control device 2 includes the coil temperature estimating means 19 and the temperature distribution estimating means 20 The estimation observer 29 may be included.
The determined gain is determined by a result of a test or a simulation, for example. This gain may be a fixed value or a variable value.

The state estimation observer 29 may have a function of changing the gain of the feedback with a correlation determined with respect to a change in the manipulated variable.
The determined correlation is determined by a result of a test or a simulation, for example.
In general, the larger the gain L is, the better the convergence speed. For example, a process for increasing the gain L when applying a large current at which the coil temperature is likely to change sharply may be added. By changing the gain L in this way, the estimated temperature of the exciting coil 4a can be corrected finely and quickly.

The control device 2 is equal to or greater than a predetermined value with respect to the maximum temperature estimated by the temperature distribution etc. estimation means 20 and a value using at least one of the differential values. At this time, it may be possible to have phase current limiting means 24 for limiting the phase current of the exciting coil 4a for which the maximum temperature is estimated.
The determined value is determined by a result of a test or a simulation, for example.

  According to this configuration, the phase current limiting means 24 determines this value for a value using at least one of the maximum temperature estimated by the temperature distribution etc. estimating means 20 and its differential value. It is determined whether or not the value has been exceeded. The phase current of the exciting coil 4a whose maximum temperature is estimated is determined by determining that the value is equal to or greater than a predetermined value. Therefore, by limiting the phase current of the exciting coil 4a when the load is concentrated on the predetermined exciting coil 4a, it is possible to reliably prevent thermal deterioration of the exciting coil 4a.

  The electric linear 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 the rotational motion of the electric motor 4 of the electric motor device Ms into a linear motion. The control device 2 has an axial force control function for controlling the axial force of the linear motion mechanism 6. When the control device 2 performs control so that the axial force of the linear motion mechanism 6 is kept constant, for example, the motor phase current is constantly applied constantly. For this reason, the loss of each exciting coil 4a varies, and each exciting coil 4a has a temperature difference. Thus, even when a temperature difference occurs in each excitation coil 4a, measures to reliably prevent thermal degradation of the excitation coil 4a should be taken by improving the temperature detection accuracy of all the excitation coils 4a. Can do.

  The electric motor device according to the present invention is an electric motor device comprising an electric motor and a control device for controlling the electric motor, wherein a temperature detecting element for detecting the temperature of the exciting coil is provided in the exciting coil of the electric motor. The control device includes: current detection means for obtaining a current to be passed through the excitation coil; current of the excitation coil obtained by the current detection means for a plurality of regions in the excitation coil; heat generation in the excitation coil; Coil temperature estimation means for calculating estimated temperatures of a plurality of regions in the excitation coil from information including heat dissipation characteristics, temperature of the excitation coil detected by the temperature detection element, and estimation by the coil temperature estimation means Comparison with the estimated temperature of the region closest to the temperature detection element among the estimated temperatures of the plurality of regions 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. For this reason, it is possible to reduce the cost and solve the mounting space problem, and it is possible to accurately estimate the temperature in consideration of the temperature distribution of the exciting coil.

It is a block diagram of the control system of the electric linear actuator which concerns on embodiment of this invention. It is a figure which shows schematically the same electric linear actuator. It is sectional drawing of the motor stator of the electric motor of the same electric linear actuator. It is an enlarged view of the A section of FIG. It is a conceptual diagram of the temperature rise of each area | region at the time of exhibiting a predetermined motor torque with the same electric linear actuator. It is a figure which shows one structural example of the coil temperature estimator and estimation error correction | amendment device of the same 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 in which the electric motor device is applied to an electric linear actuator for a vehicle is shown, but the present invention is not limited to this example.
As shown in FIG. 1, the electric motor system includes a plurality of electric linear actuators 1 provided for each vehicle wheel, 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 an electric motor 4 and a control device 2. In this embodiment, an electric brake actuator Da including an electric motor 4, a speed reduction mechanism 5, and a 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 speed reduction mechanism 5 that decelerates the rotation of the electric motor 4, a linear motion mechanism 6, a parking brake mechanism 7 that is 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 not shown. The electric motor 4 is composed of a three-phase synchronous motor or the like.

  The reduction mechanism 5 is a mechanism that reduces and transmits the rotation of the electric motor 4 to a tertiary gear 11 fixed to the rotary shaft 10, and includes a primary gear 12, an intermediate gear 13, and a tertiary gear 11. In this example, the speed reduction mechanism 5 decelerates 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 is fixed to the end of the rotation shaft 10. Can be communicated to.

  The linear motion mechanism 6, which is 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 the feed screw mechanism and abuts the friction member 9 against the brake rotor 8. It is a mechanism for separating. The linear motion part 14 is supported so as to be free of rotation and movable in the axial direction indicated by the arrow A1. A friction member 9 is provided at the outboard side end of the linear motion portion 14. 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, which is converted into the pressing force of the friction member 9. The brake force that is the axial force of the is generated. In the state where this electric brake actuator Da is mounted on the vehicle, the outside of the vehicle is referred to as the outboard side, and the center side of the vehicle is referred to as the inboard side.

  For example, a linear solenoid is applied as the actuator 16 of the parking brake mechanism 7. The actuator 16 is locked by advancing the lock member (solenoid pin) 15 and fitting it into a locking hole (not shown) formed in the intermediate gear 13, thereby inhibiting the rotation of the intermediate gear 13. Set 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 established.

  As shown in FIG. 1, a power supply device 3 and a host ECU 17 that is a host control means of each controller 2 are connected to the controller 2 of each electric motor device Ms. In FIG. 1, only one electric linear actuator 1 is shown, and other electric linear actuators are not shown. For example, an electric control unit that controls the entire vehicle is applied as the host ECU 17. The host ECU 17 has an integrated control function of each electric motor device Ms. Target value commands such as motor angular velocity, motor angle, torque, and other predetermined loads are 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 arithmetic unit 18, a coil temperature estimator 19 that is a coil temperature estimation unit, an estimation error corrector 20 that is a temperature distribution estimation unit, a motor driver 21, a current sensor 22 that is a current detection unit, and the like. Have The control arithmetic unit 18, the coil temperature estimator 19, and the estimation error corrector 20 may be implemented by a processor such as a microcomputer or a hardware module such as an ASIC, FPGA, or DSP, for example.

  The control calculator 18 includes a control calculation function unit 23 and a phase current limiting unit 24. The control calculation function unit 23 generates a control signal for the motor driver 21 from the values of various sensors so as to achieve the control target from the host ECU 17. At this time, the phase current limiting means 24 refers to the estimation result of the coil temperature estimator 19 and executes processing for 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. For example, the motor driver 21 may constitute a half bridge circuit using a switching element such as a MOSFET. The motor driver 21 may include a pre-driver that instantaneously drives the switch element.

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

  The electric motor 4 is an electric servo system in which 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 compatible with high speed, small size, and high accuracy. Is preferred. However, a functional DC motor with a brush or a stepping motor can be used as the electric motor 4. The exciting coil 4a may be concentrated winding wound around one tooth or distributed winding extending over a plurality of teeth. Comparing the two, the concentrated winding can be reduced in size, and the distributed winding can have high efficiency and high output.

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

  FIG. 4 is a partially enlarged view showing an A portion of FIG. 3 in an enlarged manner. As shown in FIGS. 3 and 4A, the temperature sensor 26, which is a temperature detection element, detects the temperature of the exciting coil 4a. A temperature sensor 26 for detecting the temperature of the exciting coil 4a is provided in any one of the three-phase exciting coils 4a in the electric motor 4. As the temperature sensor 26, a thermistor using a temperature-sensitive resistor and a voltage dividing circuit are suitable for simplicity and low cost.

  Further, in this example, the temperature sensor 26 is disposed in the gap δ between the mutually adjacent exciting coils 4a and 4a in the circumferential direction between the teeth 28a and 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 farthest from the outer surface of the tooth 28a among a plurality of regions (described later) in any one of the exciting coils 4a. The adjacent excitation coils 4a and 4a may be covered with a molding material (not shown) together with the temperature sensor 26.

  As shown in FIG. 1, as the rotor angle sensor 25, for example, a sensor such as a resolver or a magnetic encoder may be mounted on the electric motor 4, and the rotor angle is estimated without using a rotating coil voltage. You may do it. 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. When the rotor angle is estimated without a sensor, it is advantageous for space saving.

  In this embodiment, in particular, the controller 2 is provided with a coil temperature estimator 19 and an estimation error corrector 20. The control calculator 18 is provided with phase current limiting means 24. 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, Ta. For reasons described later, the temperature distribution is likely to occur due to the relationship between the inner and outer circumferences of the teeth 28a of the stator core portion 28. Therefore, the region 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 composed of a layer closest to the outer surface of the tooth 28a with respect to the tooth 28a around which the excitation coil 4a is wound, with respect to the excitation coil 4a wound around a plurality of layers provided with the temperature sensor 26. An annular region. The separation region Ra is an annular region formed of a layer that is most separated from the tooth 28a. The intermediate region Ta is an annular region composed of a layer between the adjacent region Ka and the separation region Ra.

  FIG. 4B shows an example of a heat dissipation path when the exciting coil 4a generates heat. In this example, heat radiation from the coil 4aa in the adjacent area Ka closest to the outer surface of the tooth 28a to the stator core 28 is the main heat radiation, and heat conduction according to a temperature difference occurs between the contact areas, and is located on the outermost periphery. The heat is dissipated from the separation region Ra into the air. As another example, for 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 dissipation element. In addition, how to divide the plurality of regions is set as appropriate by the designer according to each specification such as coil winding.

  FIG. 5 is a conceptual diagram of a temperature rise in each region when a predetermined motor torque is exhibited by this electric linear actuator. Due to the above-described heat dissipation and heat conduction, the intermediate region Ta of the exciting coil 4a (FIG. 4) is higher in temperature than the adjacent region Ka, and the separation region Ra is intermediate in any time during which the predetermined motor torque is exerted. The temperature is higher than that in the region Ta.

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

Here, FIG. 6 is a diagram showing a 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 based on the following heat generation and heat dissipation characteristics, for example, as a general heat transfer characteristic equation.
[Temperature change] = [Heat amount] ÷ [Heat capacity]
= ([Temperature difference from surrounding area] x [Heat transfer coefficient] + [Heat generation]) ÷ [Heat capacity]

  In the above formula, the heat capacity mainly consists of the specific heat and 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 dissipation is, for example, a temperature difference with a stator core portion, an insulator (not shown), or the like, or a heat transfer coefficient of the contact portion.

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

  By the way, the coil temperature in the region Ra where the temperature sensor 26 is provided is directly detected by the temperature sensor 26, and therefore it is not necessary to estimate it by the coil temperature estimator 19. However, there are cases where it is easily affected by noise, such as when a simple measurement system composed of a temperature-sensitive resistor and a divided circuit is constructed. In such a case, since the coil temperature estimator 19 of the present embodiment plays a 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 respect to a change in the operation amount (amount of heat generated in each region). In general, the larger the gain, the better the convergence speed. For example, a process for increasing the gain L when applying a large current that is likely to change the coil temperature rapidly may be added. By changing the gain L in this way, the estimated temperature of the exciting coil 4a can be corrected finely and quickly.

  The estimation error corrector 20 is a region closest to the temperature sensor 26 among the temperature of the exciting coil 4a detected by the temperature sensor 26 and the estimated temperatures of the regions Ra, Ka, Ta estimated by the coil temperature estimator 19 ( In this example, the estimated temperature of each region Ra, Ka, Ta estimated by the coil temperature estimator 19 is 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.

  By configuring the coil temperature estimator 19 and the estimation error corrector 20 as described above, it is possible to estimate the coil temperature of each region Ra, Ka, Ta in the exciting coil 4a. From the estimated coil temperatures of the regions Ra, Ka, Ta, the temperature distribution and local maximum temperatures of the regions Ra, Ka, Ta in the exciting coil 4a can be obtained. In addition, the code | symbol of the addition / subtraction calculating part in FIG. 6 shall be set according to numerical formula expansion at the time of mounting.

  As shown in FIG. 1, the phase current limiting unit 24 includes a determination unit 24a and a limiting unit 24b. The determination unit 24a determines this value for a value using at least one of the maximum temperature of each region Ra, Ka, Ta corrected by the estimation error corrector 20 and its differential value. It is determined whether or not the value exceeds the specified value. When it is determined that the limiter 24b is equal to or greater than the value determined by the determination unit 24a, the limiter 24b limits the phase current of the exciting coil 4a where the maximum estimated temperature is estimated.

  In this case, for example, the limiter 24b may limit the estimated phase current so as to reduce several percent to several tens of percent, or depending on one or both of the motor rotation speed and the estimated coil temperature. Thus, it may be limited to a predetermined phase current. The determined phase current is determined by a result of a test or a simulation, for example. Therefore, by limiting the phase current of the exciting coil 4a when the load is concentrated on the predetermined exciting coil 4a, it is possible to reliably prevent thermal deterioration of the exciting coil 4a.

  According to the electric motor system described above, in the case where heat generation is relatively fast compared to heat transfer, such as when a large torque is suddenly exerted, there is a temperature distribution in which a portion that is difficult to dissipate in the excitation coil generates heat locally. Can occur. Even in such a case, the estimation error corrector 20 does not observe the temperature of the entire coil, and the detected temperature of the exciting coil 4a and the regions Ra, Ka, Ta estimated by the coil temperature estimator 19 are detected. The temperature distribution and the local maximum temperature of the plurality of regions Ra, Ka, Ta in the exciting coil 4a may be estimated based on the comparison result with the estimated temperature of the region Ra closest to the temperature sensor 26 among the estimated temperatures of it can.

Therefore, in contrast to the technique for observing the temperature of the entire coil, this configuration is sufficient if the temperature sensor 26 is provided in at least one exciting coil 4a, so that the cost can be reduced and the problem of mounting space can be solved. In addition, temperature estimation considering the temperature distribution of the exciting coil 4a can be performed with high accuracy. Therefore, it is possible to improve the temperature detection accuracy when a particularly large current flows.
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 design freedom.

The temperature sensor 26 may be disposed on the inner peripheral surface of the proximity region Ka in the exciting coil 4a. In this case, for example, a recess may be provided on the outer peripheral surface of the tooth 28a, and the temperature sensor 26 may be provided in the recess.
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 nonlinear observer, the accuracy of removing error factors is increased.

  The electric motor device Ms of this embodiment may be applied to an electric press. When the pressing force of the electric press is held 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, but at least the coil temperature estimator 19 is estimated in the control device 2. By providing the error corrector 20, the coil temperature in each region of the exciting coil 4a can be obtained with high accuracy.

  As mentioned above, although the form for implementing this invention based on embodiment was demonstrated, embodiment disclosed this time is an illustration and restrictive at no points. 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 actuator 2 ... Control apparatus 4 ... Electric motor 6 ... Linear motion mechanism 4a ... Excitation coil 19 ... Coil temperature estimator (coil temperature estimation means)
20 ... Estimated error corrector (Temperature distribution estimation means)
22 ... Current sensor (current detection means)
24: Phase current limiting means 26 ... Temperature sensor (temperature detection element)
27 ... Motor stator 28 ... Stator core 28a ... Teeth Ms ... Electric motor device

Claims (6)

In an electric motor device comprising an electric motor and a control device that controls the electric motor, the excitation coil in the electric motor is provided with a temperature detection element that detects the temperature of the excitation coil,
The controller is
Current detection means for obtaining a current flowing through the exciting coil;
For the plurality of regions in the exciting coil, the estimated temperature of the plurality of regions in the exciting coil is obtained from the current of the exciting coil obtained by the current detecting means and information including heat generation and heat dissipation characteristics in the exciting coil. A coil temperature estimating means for calculating each,
Comparison result between the temperature of the exciting coil detected by the temperature detecting element and the estimated temperature of the region closest to the temperature detecting element among the estimated temperatures of the plurality of regions estimated by the coil temperature estimating means And a temperature distribution estimation means for estimating a temperature distribution of a plurality of regions or a local maximum temperature in the exciting coil based on the electric motor device. 2. The electric motor device according to claim 1, wherein the motor stator in 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 circumferential surface of the stator core portion and project in the radial direction. The excitation coil,
The plurality of regions in the exciting coil are:
The excitation coil provided with the temperature detection element and wound in a plurality of layers on a predetermined tooth, with the predetermined tooth as a reference,
The proximity region of the layer closest to the outer surface of the teeth;
A separation region of the layer farthest 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 estimation means uses a value proportional to the square of the current of the exciting coil obtained by the current detection means as an operation amount, and a state quantity and an observation quantity. Is the estimated temperature of the exciting coil in each region, the state transition matrix is the heat capacity and thermal conductivity of the exciting coil in each region, and the temperature distribution etc. estimating means includes the temperature of the exciting coil detected by the temperature detecting element and the temperature An electric motor device including feedback of a value obtained by multiplying a deviation from an observed amount by a gain determined, and wherein the control device includes a state estimation observer including a coil temperature estimation unit and a temperature distribution estimation unit.   The electric motor device according to claim 3, wherein the state estimation observer has a function of changing the gain of the feedback with a predetermined correlation with respect to a change in the operation amount.   5. The electric motor device according to claim 1, wherein the control device is at least one of the maximum temperature estimated by the temperature distribution estimation means and a differential value thereof. An electric motor device having phase current limiting means for limiting the phase current of the exciting coil whose maximum temperature has been estimated when the value is equal to or greater than a predetermined value with respect to the value using.   6. An electric motor device according to claim 1, and a linear motion mechanism that converts a rotational motion of the electric motor of the electric motor device into a linear motion, wherein the control device includes the linear motor. An electric linear actuator having an axial force control function for controlling an axial force of a moving mechanism.

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