WO2016181898A1

WO2016181898A1 - Electric motor device and electric linear motion actuator

Info

Publication number: WO2016181898A1
Application number: PCT/JP2016/063649
Authority: WO
Inventors: 唯増田
Original assignee: Ntn株式会社
Priority date: 2015-05-14
Filing date: 2016-05-06
Publication date: 2016-11-17
Also published as: JP2016220270A; JP6080894B2

Abstract

Provided are an electric motor device and electric linear motion actuator that make it possible to reduce costs and reduce workload, and to precisely find all motor coil temperatures from some motor coil temperatures or the like. A temperature sensor (26) is provided to at least one of a plurality of excitation coils (4a). A control device (2) has a current sensor (22), a coil temperature estimating means (19), and an estimation error correcting means (20). The coil temperature estimating means (19) calculates an estimated temperature of a plurality of excitation coils (4a) from a coil current found by the current sensor (22) and from information including the heat generation and heat dissipation characteristics of the excitation coils (4a). The estimation error correcting means (20) corrects the estimated temperature of all of the excitation coils (4a) estimated by the coil temperature estimating means (19) on the basis of a result of comparison between the coil temperature detected by the temperature sensor (26) for the excitation coil(s) (4a) to which the temperature sensor (26) is provided and the estimated temperature.

Description

Electric motor device and electric linear actuator

Related applications

This application claims the priority of Japanese Patent Application No. 2015-09883 filed on May 14, 2015, and is incorporated herein by reference in its entirety.

The present invention relates to an electric motor device and an electric linear actuator, and relates to a technique in which a temperature sensor is provided in some coils and a temperature estimation result of another coil is corrected from a detection result of the temperature sensor.

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 through 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 Japanese Patent Laid-Open No. 11-234964 JP 2004-208453 A

In the electric actuators as disclosed in

Patent Documents

1 and 2, if an abnormality occurs in the coil of the electric motor due to heat generation or the like, the brake function may be degraded. The space for mounting the electric motor on the vehicle is very limited, 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 occupant is deteriorated. For this reason, it may be difficult to reduce the heat generation by reducing the copper loss of the motor coil by increasing the wire diameter of the 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 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 above 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 a servo motor of a system such as an electric actuator used for a brake, current may concentrate on a predetermined coil, and heat generation may be biased. At this time, with the measure for measuring the average temperature of each coil as in Patent Document 3, there is a possibility that the system may be stopped in a state where there is still a sufficient heat load. As the above-mentioned measures, providing thermistors for all the coils may cause problems in terms of cost, wiring and assembly man-hours, and mounting space.

An object of the present invention is to provide an electric motor device and an electric linear actuator that can reduce costs and man-hours, and can accurately obtain all motor coil temperatures from some motor coil temperatures and the like. .

Hereinafter, in order to facilitate understanding, the present invention will be described with reference to the reference numerals of the embodiments for convenience.

The electric motor device of the present invention is an electric motor device DB comprising an electric motor 4 having a plurality of exciting coils 4a and a control device 2 for controlling the electric motor 4,
At least one excitation coil 4a among the plurality of excitation coils 4a in the electric motor 4 is provided with a temperature detection element 26 for detecting the temperature of the excitation coil 4a.
The control device 2
Current detection means 22 for respectively obtaining currents flowing through the plurality of exciting coils 4a;
A coil temperature estimating means 19 for calculating an estimated temperature of the plurality of exciting coils 4a 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;
Based on the comparison result between the temperature of the excitation coil 4 a detected by the temperature detection element 26 and the estimated temperature estimated by the coil temperature estimation means 19 for the excitation coil 4 a provided with the temperature detection element 26. And an estimation error correcting means 20 for correcting the estimated temperatures of all the exciting coils 4a estimated by the coil temperature estimating means 19.
The excitation coil 4 a is a coil that constitutes a magnetic pole for rotation in the electric motor 4.

According to this configuration, the current detection means 22 obtains the currents flowing through the plurality of exciting coils 4a, respectively. In this case, when detecting the three-phase current, for example, the current detection means 22 detects the current of only two phases, and the remaining one phase is subtracted from zero because the sum of the three-phase currents is zero. You may ask. The coil temperature estimating means 19 calculates estimated temperatures of the plurality of exciting coils 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 estimation error correction means 20 compares the temperature of the excitation coil 4 a detected by the temperature detection element 26 with the estimated temperature estimated by the coil temperature estimation means 19 for the excitation coil 4 a provided with the temperature detection element 26. To do. The estimation error correction unit 20 corrects the estimated temperatures of all the excitation coils 4a estimated by the coil temperature estimation unit 19 based on the comparison result. Even for the estimated temperature of the exciting coil 4a that is not detected by the temperature detecting element 26, the coil temperature can be obtained more accurately than in the prior art by performing correction based on the comparison result.

Thus, even if the temperature of each coil is not directly measured, the coil temperature can be obtained accurately and indirectly from the coil temperature and current at other points. Further, for example, in contrast to the conventional technique in which temperature detection elements are provided in all coils, this configuration only requires the temperature detection element 26 to be provided in at least one excitation coil 4a. In addition, it is possible to avoid the occurrence of a problem in terms of the space for mounting the temperature detection element 26 on the electric motor 4. Further, by estimating the temperatures of all the excitation coils 4a, it is possible to improve the temperature detection accuracy when the load is concentrated on the predetermined excitation coil 4a.

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 of each phase, The state transition matrix 27 is used as the heat capacity and thermal conductivity of the excitation coil 4a of each phase, and the estimation error correction means 20 determines the deviation between the temperature of the excitation coil 4a detected by the temperature detection element 26 and the observed amount. The control device 2 may include a state estimation observer including the coil temperature estimation unit 19 and the estimation error correction unit 20. The determined gain L is determined by, for example, a result of a test or simulation. The gain L may be a fixed value or a variable value.

The state estimation observer 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, since the larger gain L is excellent in the convergence speed, for example, processing may be performed to increase the gain L when applying a large current at which the coil temperature is likely to change sharply. 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 uses at least one of the maximum value of the estimated temperatures of all the excitation coils 4a corrected by the estimation error correction means 20 and the differential value of the estimated temperature of all the excitation coils 4a. When this value is equal to or greater than a predetermined value, the phase current limiting means 24 for limiting the phase current of the exciting coil 4a where the maximum value of the estimated temperature is estimated may be provided. The determined value is determined by a result of a test or a simulation, for example.

According to this configuration, the phase current limiting unit 24 determines whether or not a value using at least one of the maximum value of the estimated temperature and the differential value of the estimated temperature is equal to or greater than a predetermined value. judge. When it is determined that the value is equal to or greater than the predetermined value, the phase current limiting unit 24 limits the phase current of the exciting coil 4a where the estimated maximum temperature is estimated. 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 according to the present invention includes any one of the electric motor devices DB according to the present invention and a linear motion mechanism 6 that converts the rotational motion of the electric motor 4 of the electric motor device DB into a linear motion. The 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 linear actuator 1 includes a brake rotor 8, a friction member 9 that makes contact with the brake rotor 8, the linear movement mechanism 6 that makes the friction member 9 contact the brake rotor 8, and the linear movement mechanism 6. The control device 2 may control a braking force that is an axial force of the linear motion mechanism 6 by controlling the electric motor 4. In this case, the redundancy can be improved and the cost can be reduced as compared with the conventional electric brake actuator.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the invention.

The present invention will be understood more clearly from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.

It is a block diagram of a control system of the electric servo system according to the embodiment of the present invention. It is a figure which shows schematically the electric brake device of the same electric servo system. It is a figure which shows the example of mounting of the coil temperature estimation means and estimation error correction means in the same electric motor device. It is a figure which shows the operation example of the same electric motor apparatus.

An electric brake device for an electric servo system 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 servo system that is an electric brake system for a vehicle and arranged on each wheel is shown, but the present invention is not limited to this example.

As shown in FIG. 1, this electric servo system includes a plurality of electric motor devices DB (only one is shown in FIG. 1), a power supply device 3, and a host ECU 17. Each electric motor device DB includes an electric actuator (electric linear actuator) 1 and a control device 2. First, the electric actuator 1 will be described.

As shown in FIG. 2, the electric actuator 1 applicable to the electric brake device includes an electric motor 4, a speed reduction mechanism 5 that decelerates the rotation of the electric motor 4, a linear motion mechanism 6, and a parking brake that is a parking brake. A mechanism 7, a brake rotor 8, and a friction member 9 are included. 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 speed reduction mechanism 5 is a mechanism that transmits the rotation of the electric motor 4 to the rotation shaft 10 of the linear motion mechanism 6 while reducing the transmission, and includes a primary gear 12 and an intermediate gear (secondary gear) attached to the rotor shaft 4 a of the electric motor 4. Gear) 13 and a tertiary gear 11 fixed to the end of the rotary shaft 10. In this example, the speed reduction mechanism 5 can reduce the rotation of the primary gear 12 by the intermediate gear 13 and transmit it to the tertiary gear 11.

The linear motion mechanism 6 is a mechanism that 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 causes the friction member 9 to contact and separate from the brake rotor 8. 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 addition, in the state which mounted several electric motor apparatus DB (FIG. 1) in each wheel of a vehicle, the outer side of a vehicle is called the outboard side, and the center side of a vehicle is called the inboard side.

For example, a linear solenoid is applied as the actuator 16 of the parking brake mechanism 7. The parking brake mechanism 7 is locked by causing a lock member (solenoid pin) 15 to be advanced by an actuator 16 and fitted in a locking hole (not shown) formed in the intermediate gear 13. By prohibiting the rotation of 13, the parking lock state is established. The parking brake mechanism 7 allows the rotation of the intermediate gear 13 by releasing the lock member 15 from the locking hole, thereby bringing the lock member 15 into an unlocked state.

As shown in FIG. 1, a power supply device 3 and a host ECU 17 which is a host control means of each controller 2 are connected to the controller 2 of each electric motor device DB. In FIG. 1, only the control device 2 and the electric actuator 1 in one electric motor device DB are shown, and the other electric brake devices 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 for each electric motor device DB. A target value command such as a motor angular velocity, a motor angle, 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 DB. The control device 2 includes a control arithmetic unit 18, a coil temperature estimation unit 19, an estimation error correction unit 20, a motor driver 21, a current sensor 22 that is a current detection unit, and the like. The control computing unit 18, the coil temperature estimation means 19, and the estimation error correction means 20 may be implemented by a processor such as a microcomputer or a hardware module such as an ASIC, FPGA, DSP, for example.

The control arithmetic unit 18 includes a control arithmetic function unit 23 and phase current limiting means 24. The control calculation function unit 23 stores a LUT (Look Up Table) implemented in software or hardware or a software library (Library) so as to achieve the control target from the host ECU 17 from the values of various sensors. A control signal for the motor driver 21 is generated using a predetermined conversion function and hardware equivalent thereto (hereinafter referred to as “realization model”). At this time, the phase current limiting unit 24 refers to the estimation result of the coil temperature estimation unit 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 a half bridge circuit or a full bridge circuit using a switch element such as a MOSFET (metal-oxide-semiconductor field-effect transistor) or an IGBT (insulated gate bipolar transistor). . The motor driver 21 may include a pre-driver that instantaneously drives the switch element.

The current sensor 22 is a current detection means for obtaining currents flowing through the three-phase excitation coils 4a. The current sensor 22 is one of the various sensors described above. For example, a current sensor that detects a current value by detecting a magnetic field generated around the power transmission path may be used, and a shunt resistor and an operational amplifier are used. A current sensor that detects the current value by detecting the voltage drop amount may be used. When the current sensor for detecting the magnetic field is used, it can be mounted with high efficiency and high accuracy, and when the current sensor for detecting the voltage drop amount is used, it can be mounted at low cost. Also, when measuring the three-phase current, for example, measure the current of only two of the three phases, and calculate the remaining one phase by subtracting from zero because the sum of the three-phase current is zero. May be.

In the electric motor 4, a brushless DC motor including a plurality of exciting coils 4a, a rotor angle sensor 25, a temperature sensor 26, and a rotor (not shown) having permanent magnets is an electric motor that achieves both high speed, small size, and high accuracy. Since it is suitable for a servo system, it can be adopted. 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 low torque ripple.

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 may be estimated without using a rotating coil voltage. 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 estimating the rotor angle without a sensor is advantageous for space saving.

The temperature sensor 26, which is a temperature detection element, detects the temperature of the exciting coil 4a. In the present embodiment, a temperature sensor 26 for detecting the temperature of the excitation coil 4a is provided in at least one of the three-phase excitation coils 4a in the electric motor 4 or in any one of the excitation coils 4a. As the temperature sensor 26, a thermistor using a temperature-sensitive resistor and a voltage dividing circuit are suitable for simplicity and low cost. The temperature sensor 26 may be disposed so as to be in contact with the single excitation coil 4a. For example, in the case of being in the middle of adjacent coils of the concentrated winding coil, the temperature sensor 26 is disposed so as to be in contact with the plurality of

excitation coils

4a and 4a. You may do it.

In this embodiment, in particular, the control device 2 is provided with a coil temperature estimation means 19 and an estimation error correction means 20. The control calculator 18 is provided with phase current limiting means 24. More specifically, the coil temperature estimating means 19 uses the current of the exciting coil 4a obtained by the current sensor 22 and the information including the heat generation and heat dissipation characteristics in the exciting coil 4a, and more specifically, the above implementation model, multiplication or integration. Or a hardware function that can calculate and output the estimated temperature of the three-phase exciting coil 4a using a function equivalent to the above or a hardware equivalent thereto, or a software function on a processor (not shown). Here, FIG. 3 is a diagram showing an implementation example of the coil temperature estimation means 19 and the estimation error correction means 20. The control device 2 (FIG. 1) includes a linear state estimation observer including these coil temperature estimation means 19 and estimation error correction means 20. The subscripts u, v, and w in FIG. 3 indicate the u, v, and w phase parameters of the exciting coil 4a (FIG. 1), respectively.

The coil temperature estimating means 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 consists of the specific heat and volume of the substance. The heat transfer coefficient consists of the thermal conductivity of the substance, the heat transfer coefficient of the contact portion, the heat transfer area, and the heat transfer distance. The heat generation basically consists of coil copper loss.

As described above, as shown in FIGS. 1 and 3, in the coil temperature estimation means 19, the state quantity is set to the estimated temperature ^ x (t) of the excitation coil 4a of each phase, and the input operation quantity is proportional to the square of the current. The state transition matrix 27 is the heat capacity and heat transfer coefficient of the excitation coil 4a of each phase. In this coil temperature estimation means 19, the estimated coil temperature x of u, v, and w phases obtained via the integrator 28 is output to the outside and input to the phase current limiting means 24. The estimation error correction means 20 is based on the comparison result between the temperature of the excitation coil 4 a detected by the temperature sensor 26 and the estimated temperature estimated by the coil temperature estimation means 19 for the excitation coil 4 a provided with the temperature sensor 26. Specifically, the estimated temperature of all the excitation coils 4a estimated by the coil temperature estimating means 19 can be corrected and output using the above-described realization model, the multiplication function, or hardware equivalent thereto. It is composed of software functions on a hardware circuit or a processor (not shown). More specifically, the estimation error correction means 20 detects the temperature y of the exciting coil 4a detected by the temperature sensor 26 (= [yu yuv yw] ^T, where the phase element in which the temperature sensor 26 does not exist is zero). When, the deviation between the observed quantity column vector ^ y multiplied by the matrix C ₀ to the estimated temperature estimated by the coil temperature estimating unit 19, a feedback value obtained by multiplying the stipulated gain L.

The matrix C ₀ is a matrix that is set to have a predetermined vector length in accordance with the coil phase in which the temperature sensor 26 is provided. For example, when the temperature sensor 26 is provided in the u-phase excitation coil 4a, C ₀ = [1 0 0], and when the temperature sensor 26 is provided in the v-phase excitation coil 4a, C ₀ = [0 1 0], u, When the temperature sensor 26 is provided in the middle of the v-phase exciting coil 4a, C ₀ = [0.5 0.5 0] can be obtained.

At this time, when the single coil temperature is detected by the temperature sensor 26 among the above, the temperature of the coil 4a of the phase provided with the temperature sensor 26 is directly detected by the temperature sensor 26. Need not be estimated. However, the temperature sensor 26 may be easily affected by noise, for example, when a simple measurement system including a temperature sensitive resistor and a voltage dividing circuit is constructed. At this time, since the coil temperature estimating means 19 serves as a filter, the coil temperature is estimated also in the exciting coil 4a provided with the temperature sensor 26, as in the other exciting coils 4a not provided with the temperature sensor 26. It is preferable.

The observer gain L may be a fixed value or may be a variable value that changes with a predetermined correlation with respect to the change in the manipulated variable q (t). In general, since a larger gain is superior in convergence speed, for example, processing may be performed to increase the gain L when a large current is applied, in which the coil temperature is likely to change sharply. By changing the gain L in this way, the estimated temperature of the exciting coil 4a can be corrected finely and quickly. As described above, the estimated temperature of each excitation coil 4a can be corrected by using the deviation between the temperature of the excitation coil 4a detected by the temperature sensor 26 and the observed quantity column vector (that is, the estimated temperature).

The phase current limiting unit 24 includes a determination unit 24a and a limiting unit 24b. The determination unit 24a uses at least one of the maximum values of the estimated temperatures of all the excitation coils 4a corrected by the estimation error correction means 20 and the differential values of the estimated temperatures of all the excitation coils 4a. On the other hand, specifically, a hardware circuit capable of determining and outputting whether or not this value is equal to or greater than a predetermined value using the above-described implementation model, or a comparison function or hardware equivalent thereto. Alternatively, it is composed of software functions on a processor (not shown). When it is determined that the limit unit 24b is equal to or greater than the value determined by the determination unit 24a, the limit unit 24b receives the input of the determination result, and more specifically, the implementation model, the comparison function, or equivalent hardware It is constituted by a hardware function or a software function on a processor (not shown) that can output a command for limiting the phase current of the exciting coil 4a whose estimated temperature maximum value is estimated using the wear.

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 rotational speed and the estimated coil temperature. The phase current may be limited to a predetermined value. 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 by the phase current limiting means 24 when the load is concentrated on the predetermined exciting coil 4a, the thermal deterioration of the exciting coil 4a can be surely prevented.

FIG. 4 is a diagram illustrating an operation example of the electric motor device. As this operation example, an operation example of an electric servo motor system that controls an actuator axial force (brake force) represented by an electric brake will be described. FIG. 4A shows the actuator axial force, and FIG. 4B shows the motor phase current when the actuator axial force is applied. When the actuator axial force is held at a constant value during the period t1 in FIG. 4A, the motor phase current is constantly applied constantly as shown in FIG. 4B. For this reason, the loss of each excitation coil varies and a temperature difference arises in each excitation coil. Therefore, as shown in FIG. 1, in the present embodiment, the control device 2 is provided with a coil temperature estimation means 19 and an estimation error correction means 20. The control calculator 18 is provided with phase current limiting means 24.

According to the electric motor apparatus DB described above, the coil temperature estimation means 19 calculates the estimated temperature of the three-phase excitation coil 4a from the required current of the excitation coil 4a and information including heat generation and heat dissipation characteristics in the excitation coil 4a. Is calculated. The estimation error correction means 20 compares the temperature of the excitation coil 4 a detected by the temperature sensor 26 with the estimated temperature estimated by the coil temperature estimation means 19 for the excitation coil 4 a provided with the temperature sensor 26. The estimation error correction unit 20 corrects the estimated temperatures of all the excitation coils 4a estimated by the coil temperature estimation unit 19 based on the comparison result. Even for the estimated temperature of the exciting coil 4a that is not detected by the temperature sensor 26, the coil temperature can be obtained more accurately than in the prior art by performing correction based on the comparison result.

Even if the temperature of all coils is not directly measured in this way, the coil temperature can be obtained accurately and indirectly from the coil temperature and current of other points. Further, for example, in contrast to the prior art in which temperature sensors are provided in all the excitation coils, this configuration only requires the temperature sensor 26 to be provided in at least one excitation coil 4a. Therefore, the cost of the electric motor itself and the number of assembly steps can be reduced. In addition, it is possible to avoid the occurrence of a problem in terms of the space for mounting the temperature sensor 26 on the electric motor 4. Further, by estimating the temperatures of all the excitation coils 4a, it is possible to improve the temperature detection accuracy when the load is concentrated on the predetermined excitation coil 4a.

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. That is, in this embodiment, the phase current limiting means 24 is provided to limit the motor phase current.

The phase current limiting means 24 may be a process of limiting the current upper limit value according to the estimated temperature of the exciting coil 4a, or may be a process of stopping the operation when the estimated temperature exceeds a predetermined value. The process of limiting the current upper limit value can prevent the electric motor 4 from stopping undesirably, although the control calculator 18 needs to execute the calculation process. The process of stopping the operation can be performed simply and reliably. A process for limiting the current upper limit value and a process for stopping the operation may be used in combination.

FIG. 3 shows a simple configuration of a linear observer, but 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 brake device 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 phase current continues to be applied at a constant value, so that a temperature difference occurs between the excitation coils. However, the control device includes at least a coil temperature estimation means, an estimation error correction means, It is possible to obtain the coil temperature of each excitation coil with high accuracy.

As mentioned above, although the suitable form for implementing this invention based on embodiment was demonstrated referring drawings, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the above description but by the claims. Those skilled in the art will readily appreciate various changes and modifications within the obvious scope upon reviewing this specification. Therefore, such changes and modifications should be construed as being within the scope of the invention defined by the claims or within the scope equivalent thereto.

1 ... Electric actuator (Electric linear actuator)
DESCRIPTION OF SYMBOLS 2 ... Control apparatus 4 ... Electric motor 4a ... Excitation coil 6 ... Linear motion mechanism 8 ... Brake rotor 9 ... Friction member 19 ... Coil temperature estimation means 20 ... Estimation error correction means 22 ... Current sensor (current detection means)
24: Phase current limiting means 26 ... Temperature sensor (temperature detection element)

Claims

An electric motor device comprising an electric motor having a plurality of excitation coils and a control device for controlling the electric motor,
A temperature detection element for detecting the temperature of the excitation coil is provided in at least one of the plurality of excitation coils in the electric motor,
The controller is
Current detection means for respectively obtaining currents flowing through the plurality of exciting coils;
A coil temperature estimating means for calculating an estimated temperature of the plurality of exciting coils from the current of the exciting coil determined by the current detecting means and information including heat generation and heat dissipation characteristics in the exciting coil;
For the excitation coil provided with the temperature detection element, based on the comparison result between the temperature of the excitation coil detected by the temperature detection element and the estimated temperature estimated by the coil temperature estimation means, the coil temperature Estimation error correction means for correcting the estimated temperature of all exciting coils estimated by the estimation means;
An electric motor device.
2. The electric motor device according to claim 1, wherein the coil temperature estimating means uses a value proportional to the square of the current of the exciting coil obtained by the current detecting means as an operation amount, and sets a state quantity and an observation quantity for each phase. The estimated temperature of the exciting coil is used, the state transition matrix is the heat capacity and thermal conductivity of the exciting coil of each phase, and the estimated error correcting means is a deviation between the temperature of the exciting coil detected by the temperature detecting element and the observed amount. An electric motor apparatus including a state estimation observer including a coil temperature estimation means and an estimation error correction means.
3. The electric motor device according to claim 2, wherein the state estimation observer has a function of changing the gain of the feedback with a correlation determined with respect to a change in the operation amount.
4. The electric motor device according to claim 1, wherein the control device includes a maximum value of estimated temperatures of all excitation coils corrected by the estimation error correction unit, and When this value is equal to or greater than a predetermined value relative to the value using at least one of the differential values of the estimated temperature of the exciting coil, the phase current of the exciting coil in which the maximum value of the estimated temperature is estimated An electric motor device further comprising phase current limiting means for limiting.
5. 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 motion An electric linear actuator having an axial force control function for controlling the axial force of the mechanism.
6. The electric linear actuator according to claim 5, wherein the electric linear actuator includes a brake rotor, a friction member that makes contact with the brake rotor, and the linear movement mechanism that makes the friction member contact the brake rotor. And an electric linear actuator that controls the braking force, which is an axial force of the linear motion mechanism, by controlling the electric motor.