JP2019041503A - Motor-driven direct-acting actuator and motor-driven brake device - Google Patents

Abstract

To provide a motor-driven direct-acting actuator and a motor-driven brake device which allow for space-saving high output motor control by down-sizing an electric motor.SOLUTION: A motor-driven direct-acting actuator DA includes an electric motor 4, a direct-acting mechanism 6 for converting rotation of the electric motor 4 into straight movement of a direct-acting part, and a control arrangement 2 for controlling the electric motor 4. The control arrangement 2 has an angular speed estimation function part 20b for estimating the angular speed of the electric motor 4, a current limit function part 23a limiting the current for energizing the electric motor 4 to a predetermined maximum, and a maximum current adjustment function part 24 for increasing the maximum value of the current limited by the current limit function part 23a, when the angular speed estimated in the angular speed estimation function part 20b becomes larger than the predetermined angular speed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to, for example, an electric linear actuator and an electric brake device mounted on a vehicle or the like, and relates to a technology that enables space-saving and high-output motor control.

The following technologies have been proposed as electric linear actuators.
1. An electric brake actuator using an electric motor, a linear motion mechanism, and a speed reducer (Patent Document 1).
2. An electric actuator using a planetary roller mechanism and an electric motor (Patent Document 2).

JP-A-6-327190 JP 2006-194356 A

In the electric linear actuators as described in Patent Documents 1 and 2, for example, when used for an application requiring a high-speed and high-accuracy response such as an electric brake device, a desired output can be obtained within a limited mounting space of the vehicle. It may be difficult to obtain.
In particular, in the case of the electric brake device described above, it is necessary to obtain desired actuator thrust (that is, torque) and output after being configured so as not to interfere with surrounding wheels and suspension devices. At this time, when a high output is to be exhibited at a maximum motor current that is generally determined as a constant value, the motor size may increase, and an increase in mounting space and cost may become a problem.

  An object of the present invention is to provide an electric linear actuator and an electric brake device capable of reducing the size of an electric motor and performing space-saving and high-output motor control.

The electric linear motion actuator DA of the present invention includes an electric motor 4, a linear motion mechanism 6 that converts rotational motion of the electric motor 4 into linear motion of the linear motion portion 14, and a control device 2 that controls the electric motor 4. In the electric linear actuator with
The control device 2
An angular velocity estimation function unit 20b for estimating the angular velocity of the electric motor 4,
A current limiting function unit 23a for limiting the current flowing to the electric motor 4 to a predetermined maximum value;
And a maximum current adjustment function unit 24 that increases the maximum value of the current limited by the current limiting function unit 23a when the angular velocity estimated by the angular velocity estimation function unit 20b is larger than a predetermined angular velocity.
The predetermined maximum value and the predetermined angular velocity are respectively a maximum value and an angular velocity arbitrarily determined by design or the like. For example, an appropriate maximum value and angular velocity are obtained by one or both of testing and simulation. Determined.

  According to this configuration, the angular velocity estimation function unit 20 b estimates the angular velocity of the electric motor 4. The current limiting function unit 23a limits the current supplied to the electric motor 4 to a predetermined maximum value (maximum current value). The maximum current adjustment function unit 24 determines whether or not the estimated angular velocity (estimated angular velocity) is larger than a predetermined angular velocity. When the estimated angular velocity is equal to or lower than the predetermined angular velocity, the predetermined maximum current value is maintained. The maximum current adjustment function unit 24 temporarily increases the maximum current value when the estimated angular velocity is larger than the determined angular velocity.

In this way, by increasing the maximum current value in the region where the angular velocity of the electric motor 4 is large, the motor output increases and a high-speed response is possible. Therefore, it is possible to reduce the size of the electric motor 4 and perform space-saving and high-output motor control.
For example, in an actuator that performs position (load) control, such as the electric brake device 1, the motor angular velocity is relatively high in a limited situation such as panic brake or anti-skid control. Even if the current is temporarily increased, the heat load on the electric motor 4 is light and there is no problem in durability.

When the angular velocity estimated by the angular velocity estimation function unit 20b is larger than the predetermined angular velocity, the control device 2 determines the estimated angular velocity for the axial current converted as a vector component on the orthogonal axis on the rotating coordinate system. Compared with the phase of the shaft current vector when the angular velocity is equal to or lower than the predetermined angular velocity, the current vector control function is provided to change the phase of the shaft current vector in the direction reversed from the magnetic field vector phase of the rotor in the electric motor 4. And
The maximum current adjustment function unit 24 includes:
About the maximum current locus of the shaft current vector that is a norm corresponding to the maximum value of the electric motor 4 current,
A non-circular ellipse that passes through a point that becomes the maximum current vector at which the torque per current becomes the largest when the estimated angular velocity is substantially zero, and whose longitudinal direction is the vector direction that substantially coincides with the magnetic field of the rotor. The maximum current may be increased so as to form a locus.

  According to this configuration, the current vector control function uses field-weakening control that shifts the axial current vector in the direction of -180 degrees with the phase on the dq axis when the estimated angular velocity increases. In this case, the maximum current adjustment function unit 24 sets the maximum current locus of the axis current vector corresponding to the maximum current as an elliptical locus having the d axis as a substantially longitudinal direction. Thus, by increasing the maximum current value in a region where the motor angular velocity is large, the motor output increases and a high-speed response is possible.

When the angular velocity estimated by the angular velocity estimation function unit 20b is larger than the predetermined angular velocity, the control device 2 determines the estimated angular velocity for the axial current converted as a vector component on the orthogonal axis on the rotating coordinate system. Compared with the phase of the shaft current vector when the angular velocity is equal to or lower than the predetermined angular velocity, the current vector control function is provided to change the phase of the shaft current vector in the direction reversed from the magnetic field vector phase of the rotor in the electric motor 4. And
The maximum current adjustment function unit 24 includes:
About the maximum current locus of the shaft current vector that is a norm corresponding to the maximum value of the electric motor 4 current,
When the estimated angular velocity is substantially zero, it passes through a point that becomes the maximum current vector in which the torque per current becomes the largest, so that it becomes a linear trajectory with the vector direction approximately coincident with the magnetic field of the rotor as a vertex. The maximum current may be increased.

  According to this configuration, the current vector control function uses field-weakening control that shifts the axial current vector in the direction of -180 degrees with the phase on the dq axis when the estimated angular velocity increases. In this case, the maximum current adjustment function unit 24 sets the maximum current locus of the axis current vector corresponding to the maximum current as a linear locus having a vertex on the d axis. Thus, by increasing the maximum current value in a region where the motor angular velocity is large, the motor output increases and a high-speed response is possible.

The control device 2 determines a power supply capability of the power supply device 3 by using one or both of the voltage and current of the power supply device 3 that supplies power for driving the electric motor 4. The maximum current adjustment function unit 24 may increase the maximum value of the current when the power supply capability determined by the power supply monitoring function unit 26 is higher than a predetermined value.
The determined value is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by one or both of testing and simulation, for example.

  In this case, the maximum current can be increased only when the power supply device 3 is normal and has sufficient power supply capability. For example, when an abnormality occurs in the power supply device 3 and the like, it is possible to prevent the electric linear actuator DA from becoming unusable after the power is excessively consumed. Therefore, the redundancy of the electric linear actuator DA can be increased.

  The electric brake device 1 according to the present invention provides braking force by contact between the electric linear actuator DA described above, the friction material 9 operated by the electric linear actuator DA, and the friction material 9. And a brake rotor 8 to be generated. According to this electric brake device 1, since any one of the electric linear actuators DA is provided, it is possible to control the motor with high output and space saving.

  An electric linear actuator of the present invention includes an electric motor, a linear motion mechanism that converts rotational motion of the electric motor into linear motion of a linear motion portion, and a control device that controls the electric motor. In the dynamic actuator, the control device includes an angular velocity estimating function unit that estimates an angular velocity of the electric motor, a current limiting function unit that limits a current to be supplied to the electric motor to a predetermined maximum value, and the angular velocity estimating function unit. And a maximum current adjustment function unit that increases a maximum value of the current limited by the current limiting function unit when the angular velocity estimated in (1) becomes larger than the predetermined angular velocity. For this reason, it is possible to reduce the size of the electric motor and perform space-saving and high-output motor control.

  An electric brake device according to the present invention includes any one of the electric linear actuators described above, a friction material operated by the electric linear actuator, and a brake rotor that generates a braking force by contact with the friction material. Therefore, it is possible to reduce the size of the electric motor and perform space-saving and high-output motor control.

It is a figure showing roughly the electric brake equipment concerning the embodiment of this invention. It is a block diagram of a control system of an electric linear actuator of the electric brake device. It is a figure which shows the example of the locus | trajectory of the current norm on the dq axis by the maximum electric current adjustment function part of the same electric linear actuator. It is a block diagram which shows the example which performs the same maximum current adjustment function part. It is a block diagram of the control system of the electric linear actuator of the electric brake device which concerns on other embodiment of this invention. It is a figure which shows the example of the locus | trajectory of the current norm on the dq axis by the maximum current adjustment function part of the electric linear actuator which concerns on further another embodiment of this invention. It is a figure which shows the example of the locus | trajectory of the current norm on the dq axis by the maximum current adjustment function part of the electric linear actuator which concerns on further another embodiment of this invention. It is a block diagram which shows the example which performs the maximum electric current adjustment function part of the electrically driven linear actuator which concerns on further another embodiment of this invention.

An electric brake device according to an embodiment of the present invention will be described with reference to FIGS. This electric brake device is mounted on a vehicle, for example.
As shown in FIG. 1, the electric brake device 1 includes an electric linear actuator DA and a friction brake BR. First, the structure of the electric linear actuator DA and the friction brake BR will be described.

<Structure of electric linear actuator DA and friction brake BR>
As shown in FIGS. 1 and 2, the electric linear actuator DA includes an actuator main body AH, a power supply device 3, and a control device 2 described later. The actuator body AH includes an electric motor 4, a speed reduction mechanism 5, a linear motion mechanism 6, a parking brake device 7, an angle sensor Sa, and a load sensor Sb.

As shown in FIG. 1, the electric motor 4 is composed of, for example, a permanent magnet type synchronous motor. When a permanent magnet type synchronous motor is applied as the electric motor 4, space is saved and high torque is preferable.
The friction brake BR includes a brake rotor 8 that rotates in conjunction with the wheels of the vehicle, and a friction material 9 that contacts the brake rotor 8 and generates a braking force. The friction material 9 is operated by an electric linear motion actuator DA. It is possible to use a mechanism in which the friction material 9 is operated by the actuator body AH of the electric linear actuator DA and pressed against the brake rotor 8 to generate a braking force by the frictional force.

  The reduction mechanism 5 is a mechanism that reduces the rotation of the electric motor 4, 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 transmits it to the tertiary gear 11 fixed to the end of the rotation shaft 10. It is possible.

  The linear motion mechanism 6 is a mechanism for converting 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 bringing the friction material 9 into contact with and separated 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 material 9 is provided on 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 a pressing force of the friction material 9 to generate a braking force. . In the state where the electric brake device 1 is mounted on the vehicle, the outer side in the vehicle width direction of the vehicle is referred to as the outboard side. The center side in the vehicle width direction of the vehicle is called the inboard side.

  For example, a linear solenoid is applied as the actuator 16 of the parking brake mechanism 7. The locking member 15 is advanced by the actuator 16 and is locked by being fitted into a locking hole (not shown) formed in the intermediate gear 13, and the parking gear is locked by prohibiting the rotation of the intermediate gear 13. To. 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. 2, the angle sensor Sa detects the rotation angle of the electric motor 4. As the angle sensor Sa, for example, a resolver or a magnetic encoder is preferably used because it is highly accurate and reliable, but various sensors such as an optical encoder may be used. Instead of using the angle sensor Sa, in the control device 2 to be described later, angle sensorless estimation that estimates the motor angle from the relationship between the voltage and current of the electric motor 4 can be used.

  The load sensor Sb detects the axial load of the linear motion mechanism 6. As the load sensor Sb, for example, a magnetic sensor, a strain sensor, a pressure sensor, or the like that detects displacement or deformation of a predetermined member to which the load of the linear motion mechanism 6 acts can be used. Instead of using the load sensor Sb, the control device 2 may perform the load sensorless estimation from the motor angle and the electric brake device rigidity, the motor current, the electric linear actuator efficiency, or the like. Alternatively, for example, other external sensors such as a wheel torque of a wheel on which a brake is mounted or a sensor for detecting a longitudinal force of a vehicle on which the electric brake device 1 (FIG. 1) is mounted may be used. Further, various sensors such as a thermistor may be separately provided as necessary.

<Configuration of control device 2>
FIG. 2 is a block diagram of a control system of the electric linear actuator DA of the electric brake device. For example, a control device 2 and an actuator main body AH corresponding to each wheel are provided. Each control device 2 controls a corresponding electric motor 4. Connected to each control device 2 is a DC power supply device 3 and a host ECU 17 which is a host control means of each control device 2. The power supply device 3 supplies power to the electric motor 4 and the control device 2. As the power supply device 3, for example, a low voltage (for example, 12V) battery of a vehicle on which the electric brake device 1 (FIG. 1) is mounted can be applied.

  For example, an electric control unit (VCU) that controls the entire vehicle is applied as the host ECU 17. The host ECU 17 has an integrated control function of each control device 2. The host ECU 17 includes command means 17a, and the command means 17a outputs a target load command value to each control device 2 in accordance with the output of the sensor that changes according to the operation amount of the brake operation means (not shown). To do. Note that the command means 17a may be the brake operation means itself, or, for example, determines braking in an automatically driven vehicle without depending on the operation of the brake operation means, and sends a load command value (brake force command) to each control device 2. Value) can also be output.

  Each control device 2 includes various control calculation function units that perform control calculations and a motor driver 18. The various control arithmetic function units are constituted by, for example, a processor such as a microcomputer, an arithmetic unit such as an FPGA or an ASIC, and a peripheral circuit. The various control calculation function units include a load estimation function unit 19, a motion estimation function unit 20, a current estimation function unit 21, a load control function unit 22, a current command function unit 23, a maximum current adjustment function unit 24, and a current control function unit 25. Is provided.

The load estimation function unit 19 estimates the axial load (estimated load) of the linear motion mechanism 6 from the output of the load sensor Sb and the like. Or when performing load sensorless estimation, you may comprise the load estimation function part 19 so that the axial direction load of the linear_motion | direct_drive mechanism 6 may be estimated using information, such as a motor angle and an electric current.
The motion estimation function unit 20 estimates the rotational motion state of the electric motor 4 from the output of the angle sensor Sa and the like. The motion estimation function unit 20 includes a position / phase estimation unit 20a and an angular velocity estimation function unit 20b.

  In the position / phase estimation unit 20a, for example, when a sensor that detects a predetermined angle region such as a resolver or an encoder as one period is used as the angle sensor Sa, the rotor phase of the electric motor 4 is estimated from the output of the angle sensor Sa. Then, the integrated value of the variation amount of the rotor phase may be estimated as the total rotation angle (position). Further, the angular velocity estimation function unit 20b may estimate the differential value of the rotor phase or position as the angular velocity. Alternatively, for example, when the angle sensorless estimation described above is performed, the phase and angular velocity may be estimated from the voltage and current of the electric motor 4.

  The current estimation function unit 21 estimates a motor current. The current estimation function unit 21 may estimate the motor current using, for example, a current sensor (not shown) provided on the current path of the phase current of the electric motor 4. As the current sensor, a contact sensor such as a shunt resistor and an amplifier, or a non-contact sensor such as a magnetic sensor disposed in the vicinity of the energization path can be used.

The current sensor may be arranged to detect, for example, a three-phase motor phase current, and detects the two phases of the three-phase motor phase currents, and the remaining one phase from the relationship that the three-phase sum is zero. You may arrange | position so that it may detect.
Alternatively, the current estimation function unit 21 may be a current sensorless estimation that estimates the motor current from the motor voltage and the motor coil characteristics, or, for example, a current sensor that detects a positive current or a negative primary current, a voltage, and a motor A combination of current sensor and current sensorless estimation, such as estimating the motor phase current from the coil characteristics, may be used.

  The load control function unit 22 controls the electric motor 4 so that the estimated load calculated by the load estimation function unit 19 follows the target load command value (actuator load command) given from the command unit 17a. Control the amount of operation. The operation amount may be, for example, a target motor torque or a current norm. In particular, when the motor torque is used as an operation amount, a current command function unit 23 described later may have a function of a current converter for torque.

  The current command function unit 23 has a function of generating a target current for the electric motor 4. The current command function unit 23 includes a current limit function unit 23a and a command current calculation unit 23b. The current limiting function unit 23a limits the magnitude of the current supplied to the electric motor 4 to a predetermined maximum value. The current limiting function unit 23a in this example has a function of limiting the target current so that the magnitude of the motor current is equal to or less than a predetermined value. The command current calculation unit 23b may have a function of generating a current command value in a current control function unit 25 to be described later within the range of the limit current by the current limit function unit 23a.

  The current command value may be, for example, a current vector on an orthogonal axis on a predetermined rotational coordinate system, or may be a current command value of a three-phase alternating current. It is preferable to use an axis current corresponding to the d-axis and the q-axis orthogonal to the d-axis because a simple and high-performance current control system can be configured.

  The maximum current adjustment function unit 24 can have a function of changing the limit current in the current command function unit 23 according to conditions. The maximum current adjustment function unit 24 has a function of increasing the maximum value of the current limited by the current limiting function unit 23a when the angular velocity estimated by the angular velocity estimation function unit 20b is larger than the predetermined angular velocity. The function of increasing the maximum current value improves the maximum output of the electric motor 4 and enables a high-speed response in the electric linear actuator DA.

The current control function unit 25 can have a function of controlling the motor voltage so that the estimated current estimated by the current estimation function unit 21 follows the current command value.
The motor driver 18 controls the power supplied to the coil of the electric motor 4. The motor driver 18 constitutes a half bridge circuit using a switching element such as a field effect transistor (abbreviated as FET), and PWM control for determining a motor applied voltage based on an ON-OFF duty ratio of the switching element. If it is the structure which performs, it will become inexpensive and high performance. Or it can also be set as the structure which provides a transformer circuit etc. and performs PAM control.

  In addition, the configuration of a current sensor or the like that is not shown can be provided as needed. In addition, each functional unit is provided as a block for convenience, and may be integrated and divided as necessary, or a predetermined functional unit may be omitted as appropriate.

<Example of limit current vector>
FIG. 3 is a diagram illustrating an example of a locus of a current norm on the dq axis by the maximum current adjustment function unit of the electric linear actuator. This will be described with reference to FIG. The d-axis in FIG. 3 coincides with the direction of the rotor magnetic flux when there is no load.

  In the example of FIG. 3, the maximum current adjustment function unit 24 uses the maximum current norm corresponding to the maximum value of the electric motor 4 as an elliptical locus. That is, the maximum current adjustment function unit 24 passes through the maximum current phase (θmax) at which the torque per current is maximum, and is a non-circular elliptical locus Kd whose longitudinal direction is approximately the negative d-axis direction (weakening magnetic flux direction). Change the maximum current so that In addition, the dotted line which becomes a perfect circle in a figure shows the locus | trajectory at the time of making the conventional maximum current (current limitation) constant.

  The maximum current phase (θmax) is approximately 90 ° particularly in a surface magnet type synchronous motor, and a predetermined phase angle in a motor having a saliency typified by an embedded magnet type synchronous motor. In general, the maximum current locus of the axis current vector is often a symmetrical locus in which the direction of the torque is reversed with respect to the d-axis. However, the maximum current locus is asymmetric with respect to the d-axis and has a different maximum current depending on the direction of the torque. Also good. Alternatively, different trajectories can be applied for power running and regeneration.

  In this control device 2, when the angular velocity estimated by the angular velocity estimation function unit 20b becomes larger than the predetermined angular velocity, a control method (weak magnetic flux control) is used to increase the negative d-axis current and suppress the induced voltage. . In other words, when the estimated angular velocity is larger than the determined angular velocity, the control device 2 determines that the estimated angular velocity is equal to or less than the determined angular velocity for the axial current converted as a vector component on the orthogonal axis on the rotating coordinate system. Compared with the phase of the shaft current vector, the current vector control function is provided to change the phase of the shaft current vector in the direction reversed from the magnetic field vector phase of the rotor in the electric motor 4.

  Therefore, when the control device 2 has the current vector control function, the maximum current locus of the axial current vector that becomes the maximum current norm is elliptical as shown in FIG. The value increases and the motor output can be improved.

  As a contradiction, the heat load on the electric motor 4 increases as the maximum current value increases. However, for example, in an electric linear actuator DA that performs position control or load control such as an electric brake device, the magnitude of the motor angular velocity is increased temporarily such as panic brake or anti-skid control in the electric brake device. It is considered that it is easy to ensure durability against the heat load of the electric motor 4.

<System configuration example>
FIG. 4 is a block diagram illustrating an example in which the maximum current adjustment function unit is executed. This will be described with reference to FIG. FIG. 4 shows an example in which the maximum current limiting function shown in FIG. 3 is directly implemented as the maximum current limiter 24a as the maximum current adjustment function unit 24. A load control controller 22a is mounted as the load control function unit 22, and the current command function unit 23 includes a torque → current converter 23c that converts a target motor torque into a current. In addition, a current control controller 25 a is mounted as the current control function unit 25.

  The maximum current limiter 24a and the maximum torque limiter 24b (FIG. 8), which will be described later, include, for example, a lookup table (Lookup table: abbreviated as LUT) for each limit value according to motor characteristics obtained in advance through analysis or measurement. Although it is preferable to reduce the calculation load, for example, a predetermined calculation expression that is calculated based on the motor characteristics such as phase resistance or inductance can also be used.

<About the effects>
According to the electric linear actuator DA and the electric brake device 1 described above, the current limiting function unit 23a limits the current supplied to the electric motor 4 to the maximum current value. The maximum current adjustment function unit 24 determines whether or not the estimated angular velocity is greater than a predetermined angular velocity. When the estimated angular velocity is equal to or lower than the predetermined angular velocity, the predetermined maximum current value is maintained. The maximum current adjustment function unit 24 temporarily increases the maximum current value when the estimated angular velocity is larger than the determined angular velocity. In this way, by increasing the maximum current value in the region where the angular velocity of the electric motor 4 is large, the motor output increases and a high-speed response is possible. Therefore, it is possible to reduce the size of the electric motor 4 and perform space-saving and high-output motor control.

<About other embodiments>
In the following description, the same reference numerals are given to portions corresponding to the matters described in advance in the respective embodiments, and overlapping descriptions are omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in advance unless otherwise specified. The same effect is obtained from the same configuration. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

  As illustrated in FIG. 5, the control device 2 may include a power supply monitoring function unit 26. For example, the power supply monitoring function unit 26 may estimate the voltage of the power supply device 3 and determine that the power supply capability of the power supply device 3 has decreased when the estimated voltage falls below a predetermined value. Alternatively, the power supply monitoring function unit 26 estimates the current of the power supply device 3 together, and can determine that the power supply capability of the power supply device 3 has decreased when the voltage fluctuation at the time of current output becomes larger than a predetermined value. Alternatively, for example, a higher-level current monitoring function unit (not shown) such as a battery manager that calculates a% SOC (State Of Charge) that is a percentage of the charge state from the integrated value of the current value of the power supply device 3 is provided. The monitoring function unit 26 may determine the power supply capability of the power supply device 3 through communication from the upper current monitoring function unit.

  Improving the maximum output of the electric motor 4 temporarily by the maximum current adjustment function unit 24 temporarily increases the maximum load of the power supply device 3. For this reason, in this configuration, the power supply monitoring function unit 26 is provided, and when the power supply capability of the power supply device 3 is reduced, an increase in the maximum current by the maximum current adjustment function unit 24 is suppressed or not executed. May be preferable from the viewpoint of redundancy. Also, the maximum current can be increased only when the power supply device 3 is normal and has sufficient power supply capability. For example, when an abnormality occurs in the power supply device 3 and the like, it is possible to prevent the electric linear actuator DA from becoming unusable after the power is excessively consumed. Therefore, the redundancy of the electric linear actuator DA can be increased.

As shown in FIG. 6, the maximum current adjustment function unit 24 sets a linear maximum current locus (straight line locus) Ks having a vertex on the d-axis as a locus for increasing the maximum current as in FIG. May be. Although FIG. 6 shows an example in which the maximum current locus Ks is a straight line for one quadrant, for example, it may be a locus with an appropriate break point.
The elliptical trajectory method of FIG. 3 and the linear trajectory method of FIG. 6 can be used together as appropriate. For example, the maximum current locus may be such that the predetermined area is a straight line and the other predetermined area is an ellipse.

  FIG. 7 shows a case where the maximum current adjustment function unit 24 further increases the maximum current phase according to the maximum current phase until the angular velocity magnitude (| ω |) reaches a predetermined value (| ω | = a). An example of increasing the current is shown. Generally, until the magnitude of the motor angular velocity reaches the predetermined value, current vector control can be performed at the maximum current phase without performing the flux-weakening control. Therefore, as shown in FIG. 7, in contrast to the example of FIG. 3, the maximum current adjustment function unit 24 further increases the angular velocity magnitude (| ω |) until a predetermined value (| ω | = a) is reached. By increasing the maximum current according to the maximum current phase, the effect of temporarily increasing the motor output can be used more actively.

  In general, since current vector control (intensifying magnetic flux control) using a positive d-axis current that enhances the rotor magnetic flux is not performed, although not shown, when performing control to increase the positive d-axis current, For example, in the strong magnetic flux region, a conventional perfect circular maximum current may be used, or an ellipse or a straight line may be used.

  FIG. 8 is a block diagram showing another system configuration example for executing the maximum current adjustment function unit 24. FIG. 8 shows an example in which a maximum torque limiter 24b that limits torque according to the magnitude of the motor angular velocity is provided as the maximum current adjustment function unit 24. In this example, compared to the case where the maximum current is constant, by setting the maximum torque limit value when the magnitude of the angular velocity is increased, the current value for exerting the torque increases, and as a result The maximum current locus as shown in any of FIG. 3, FIG. 6, or FIG.

  As the conversion mechanism portion of the linear motion mechanism 6, various screw mechanisms such as a planetary roller and a ball screw, a mechanism using an inclination of a ball ramp, and the like can be used.

  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 brake device 2 ... Control apparatus 3 ... Power supply device 4 ... Electric motor 6 ... Linear motion mechanism 8 ... Brake rotor 9 ... Friction material 14 ... Linear motion part 20b ... Angular velocity estimation function part 23a ... Current limiting function part 24 ... Maximum Current adjustment function part 26 ... Power supply monitoring function part DA ... Electric linear actuator

Claims (5)

In an electric linear motion actuator comprising an electric motor, a linear motion mechanism that converts the rotational motion of the electric motor into a linear motion of the linear motion portion, and a control device that controls the electric motor,
The control device includes:
An angular velocity estimation function unit for estimating an angular velocity of the electric motor;
A current limiting function unit that limits a current to be supplied to the electric motor to a predetermined maximum value;
An electric linear actuator having a maximum current adjustment function unit that increases a maximum value of a current limited by the current limiting function unit when the angular velocity estimated by the angular velocity estimation function unit becomes larger than a predetermined angular velocity. 2. The electric linear actuator according to claim 1, wherein when the angular velocity estimated by the angular velocity estimating function unit is larger than a predetermined angular velocity, the control device converts the vector as a vector component on an orthogonal axis on a rotational coordinate system. Compared with the phase of the axial current vector when the estimated angular velocity is equal to or lower than the predetermined angular velocity, the axial current vector is shifted in the direction reversed from the magnetic field vector phase of the rotor in the electric motor. Has a current vector control function to change the phase,
The maximum current adjustment function unit includes:
About the maximum current locus of the shaft current vector that is a norm corresponding to the maximum value of the electric motor current,
A non-circular ellipse that passes through a point that becomes the maximum current vector at which the torque per current becomes the largest when the estimated angular velocity is substantially zero, and whose longitudinal direction is the vector direction that substantially coincides with the magnetic field of the rotor. Electric linear actuator that increases the maximum current so as to form a locus. 2. The electric linear actuator according to claim 1, wherein when the angular velocity estimated by the angular velocity estimating function unit is larger than a predetermined angular velocity, the control device converts the vector as a vector component on an orthogonal axis on a rotational coordinate system. Compared with the phase of the axial current vector when the estimated angular velocity is equal to or lower than the predetermined angular velocity, the axial current vector is shifted in the direction reversed from the magnetic field vector phase of the rotor in the electric motor. Has a current vector control function to change the phase,
The maximum current adjustment function unit includes:
About the maximum current locus of the shaft current vector that is a norm corresponding to the maximum value of the electric motor current,
When the estimated angular velocity is substantially zero, it passes through a point that becomes the maximum current vector in which the torque per current becomes the largest, so that it becomes a linear trajectory with the vector direction approximately coincident with the magnetic field of the rotor as a vertex. Electric linear actuator that increases the maximum current.   The electric linear actuator according to any one of claims 1 to 3, wherein the control device is one or both of a voltage and a current of a power supply device that supplies electric power for driving the electric motor. The power supply monitoring function unit for determining the power supply capability of the power supply device, and the maximum current adjustment function unit, when the power supply capability determined by the power supply monitoring function unit is higher than a predetermined value, Electric linear actuator that increases the maximum current.   5. The electric linear actuator according to claim 1, a friction material operated by the electric linear actuator, and a brake rotor that generates a braking force by contact with the friction material. And an electric brake device.

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