JP4503267B2 - Method and apparatus for high-speed positioning of electric motor - Google Patents

Description

  The present invention relates to a method and an apparatus for positioning a motor on which a load caused by a Coulomb friction and a load caused by a change in moment of inertia act at high speed.

  FIG. 4 illustrates the configuration of a conventional apparatus for positioning an electric motor. In FIG. 4, a current detector 107 detects a current flowing through a stator of an electric motor (permanent magnet type synchronous motor, induction motor, etc.) 108, and a position detector (for example, constituted by an encoder) 109 A number of pulse signals corresponding to the angular displacement of the rotor of the electric motor 108 are output as position detection signals. The position / speed converter 110 detects the amount of change in the rotor position per unit time, that is, the rotational speed of the electric motor 108 based on the output of the position detector 109.

The deviation counter 102 counts the position command pulse output from the pulse oscillator 101 and the feedback pulse output from the position detector 109, and detects the deviation, that is, the position deviation of the electric motor 108.
The speed controller 103 inputs the position deviation output from the deviation counter 102 as a speed command, and the value of this speed command and the actual rotational speed value of the motor 108 output from the position / speed converter 110. And output an appropriate current command corresponding to the difference between the two.

The current controller 104 gives an appropriate instruction voltage to the inverter 106 corresponding to the difference between the value of the current command output from the speed controller 103 and the stator current detected by the current detector 107. Therefore, the inverter 106 forms the instruction voltage from the current controller 104 based on the output of the AC power source 105 and applies it to the motor (for example, see Non-Patent Document 1).
According to this control device, the rotor of the electric motor 108 is positioned at the position commanded by the position command pulse.

FIGS. 5A, 5B and 5C show the ideal torque current i, the speed ω _m of the motor 108, and the position of the motor 108 when the motor 108 is positioned in the shortest time using the above-described apparatus. This is an example of each time change pattern of θ _m .
As shown in FIG. 5, in order to position the electric motor 108 in the shortest time, first, a voltage at which the maximum torque component current i _torque flows is applied to the electric motor 108 to accelerate the electric motor 108 with the maximum torque. . As a result, the motor 108 is accelerated rapidly until the speed ω _m reaches its limit value (the rated maximum speed of the motor 108) ω _max .
Thereafter, until a certain point before reaching the target position θ _m ^ref , the electric motor 108 is driven so that the maximum speed ω _max is maintained. Torque component current -i _torque is applied to the motor 108 to decelerate the motor 108.

In short, in order to position the electric motor 108 in the shortest time, it is necessary to generate a speed command that changes in the pattern shown in FIG. The speed command output from the deviation counter 102 is formed by a pool pulse in the deviation counter 102. The number of pool pulses tends to increase as the frequency of the output pulse of the pulse oscillator 101 increases. Therefore, the frequency of the output pulse of the pulse oscillator 101 is appropriately set based on the target position θ _m ^ref , the speed limit value ω _max , the current limit values i _torque , −i _torque of the motor 108, and the speed command as described above is issued. Will be generated.
"Introduction to AC Servo Motor" 5th edition, Oriental Motor Co., Ltd., November 1997, p. 12

However, in the high-speed positioning method using the above-described device, when the target position is changed, when a load due to a change in the Coulomb load or moment of inertia acts on the motor 108, or a load due to a change in the Coulomb load or moment of inertia. When is changed, it is necessary to recalculate the target position command based on the speed command pattern.
Further, in the above method, a pulse oscillator or the like for generating a speed command pattern is required, and since the accumulated pulse of the deviation counter 102 is used for the command speed, the time required for accumulating the accumulated pulse is Usually, positioning of the electric motor 108 is delayed.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a high-speed positioning method for an electric motor capable of self-generating a high-speed positioning speed command adapted to the target position and load of the electric motor. To provide an apparatus.

ただし、ω_m：電動機の実速度
ｋ_t：電動機のトルク係数
Ｊ_M：電動機の慣性モーメント
Ｊ_L：負荷となる慣性モーメント
i_torque：最大トルクを出力するための電動機のトルク分電流
Ｔ_LC：電動機に対するクーロン摩擦負荷 In order to achieve the above object, a high-speed positioning method for an electric motor according to the present invention includes a step of detecting a position deviation, and comparing the position deviation with a first reference value and a second reference value smaller than the reference value. A speed command for instructing an allowable maximum speed of the motor when the position deviation is greater than or equal to the first reference value, and when the position deviation is greater than or equal to the second reference value and smaller than the first reference value. Generating a speed command for instructing zero speed, a speed command for instructing a speed corresponding to the position deviation when the position deviation is smaller than the second reference value, and a speed of the motor being the speed command And driving the electric motor so as to achieve a speed corresponding to the first reference value. The first reference value is set based on the following equation.

Where ω _{m is} the actual speed of the motor
k _t : Torque coefficient of the motor
J _M : Moment of inertia of the motor
J _L : Moment of inertia
i _torque ： The torque component current of the motor to output the maximum torque
T _LC : Coulomb friction load on the motor

  According to this positioning control method, the speed command for high-speed positioning adapted to the target position of the motor, the Coulomb friction load, and the load due to the variation of the moment of inertia is self-generated, and the motor is driven based on this speed command.

  The moment of inertia that becomes the load of the motor can be estimated based on the drive current, speed, and acceleration of the motor. The speed command may be subjected to anti-windup compensation.

ただし、ω_m：電動機の実速度
ｋ_t：電動機のトルク係数
Ｊ_M：電動機の慣性モーメント
Ｊ_L：負荷となる慣性モーメント
i_torque：最大トルクを出力するための電動機のトルク分電流
Ｔ_LC：電動機に対するクーロン摩擦負荷 On the other hand, the high-speed positioning device for an electric motor according to the present invention includes a deviation detecting unit that detects a positional deviation of the electric motor, and compares the positional deviation with a first reference value and a second reference value smaller than the reference value, A speed command for instructing an allowable maximum speed of the electric motor when the position deviation is equal to or greater than the first reference value is zero when the position deviation is equal to or greater than the second reference value and smaller than the first reference value. A speed command generating means for generating a speed command for instructing a speed corresponding to the position deviation when the position deviation is smaller than the second reference value, and a speed of the motor is the speed Drive means for driving the electric motor so that the speed corresponds to the command, and the first reference value is set based on the following equation.

Where ω _{m is} the actual speed of the motor
k _t : Torque coefficient of the motor
J _M : Moment of inertia of the motor
J _L : Moment of inertia
i _torque ： The torque component current of the motor to output the maximum torque
T _LC : Coulomb friction load on the motor

  Means for detecting the drive current, speed, and acceleration of the electric motor, and means for estimating the moment of inertia that becomes the load of the electric motor based on the drive current, speed, and acceleration can be provided. Further, a compensation means for performing antiwindup compensation on the speed command can be further provided.

According to the high-speed positioning method and apparatus for an electric motor according to the present invention, the high-speed positioning speed command adapted to the target position, the coulomb friction load torque, and the load torque due to the variation of the inertia moment is self-generated, so the target position is set. Therefore, the electric motor is positioned at the target position at high speed. Therefore, it is possible to easily and quickly cope with a change in load due to fluctuations in the target position, coulomb friction load, and moment of inertia.
Further, since a pulse oscillator and a deviation counter are not used as means for generating a speed command, there is an advantage that positioning control response is improved.

Embodiments of a high-speed positioning method and apparatus for an electric motor according to the present invention will be described below with reference to the drawings.
(A), (b) and (c) of FIG. 2 illustrate the ideal position, speed, and torque variation pattern of the motor when the motor is positioned at high speed, respectively. Note that (a), (b), and (c) in FIG. 2 correspond to (c), (b), and (a) in FIG. 5, respectively.

As described above, in order to position the motor at high speed, an allowable maximum current (maximum torque component current) i _torque is passed through the motor to accelerate the motor to the maximum speed ω _max (region t ₀ < t ≦ t ₁ ), a current that maintains the maximum speed ω _max is supplied to the motor (region t ₁ <t ≦ t ₂ ), and then an allowable maximum current −i _torque is supplied to the motor to decelerate the motor (region t ₂ <t ≦ t ₃ ).
In other words, in order to position the motor at a high speed, it is only necessary to give a speed command to the control system so that the speed of the motor changes according to the pattern of FIG.

The velocity pattern of FIG. 2 (b) is analyzed as follows.
(1) Region (t ₀ <t ≦ t ₁ ): The acceleration is fixed by the maximum allowable current of the motor.
(2) Region (t ₁ <t ≦ t ₂ ): The electric motor is operated at the maximum speed.
(3) Region (t ₂ <t ≦ t ₃ ): The deceleration is fixed by the allowable maximum current of the motor.
(4) Region (t ₃ > t): Continue to issue a speed command to bring the speed close to zero.

  The above analysis results show that the ideal speed pattern shown in FIG. 2B can be obtained by setting the speed command as shown in FIG.

  By the way, the ideal speed pattern for positioning the electric motor in the shortest time changes depending on the target position, and the load fluctuation caused by the fluctuation of the Coulomb friction load and the moment of inertia acting on the electric motor. Therefore, the ideal speed pattern shown in FIG. 2B is only an example.

FIG. 1 shows an embodiment of a positioning device according to the present invention for positioning an electric motor at high speed. In this positioning device, a high-speed positioning speed command as illustrated in FIG. 2D is self-generated.
In FIG. 1, a current detector 7 detects a current (for example, a stator current) i flowing through the electric motor 8, and a position detector 9 detects an actual position (actual rotation position of the rotor) θ _m of the electric motor 8. Further, the position / speed converter 10 detects the actual speed ω _m of the electric motor 8 based on the time change of the actual position θ _m of the electric motor 8. As the motor 8, a permanent magnet type synchronous motor, an induction motor, a brushed synchronous motor, or the like is applied.

The position controller 2 calculates a deviation between the target position θ _m ^ref given from the target position input device 1 and the actual position θ _m of the electric motor 8 and outputs a speed command corresponding to the position deviation. Further, the speed controller 3 outputs an appropriate current command corresponding to the deviation between the target speed ω _m ^ref indicated by the speed command and the actual speed ω _m of the electric motor 8 to the current controller 4. The speed controller 3 has an anti-windup function (which will be described later) for driving the motor 8 stably even when a large speed deviation occurs.

  The current controller 4 gives the inverter 6 an appropriate instruction voltage corresponding to the difference between the current indicated by the current command output from the speed controller 3 and the current detected by the current detector 7. The inverter 6 has a known configuration in which the voltage input from the AC power supply 5 is subjected to pulse width modulation based on the instruction voltage from the current controller 4 and a modulation output voltage corresponding to the instruction voltage is applied to the motor 8. .

The load estimator 11 is based on the actual speed ω _{m of} the motor 8 and the current i detected by the current detector 7, and loads T _L (Coulomb friction load torque T _LC and moment of inertia acting on the motor 8. is intended to estimate the variation J _L by those plus the load torque), it has a configuration as a so-called disturbance observer.
Since the principle and configuration of the disturbance observer are well known, description thereof is omitted here.

The speed / acceleration converter 12 detects the acceleration α of the electric motor 8 based on the time change of the actual speed ω _m of the electric motor 8 obtained by the position / speed converter 10.
Load separator 13, a load T _L of the motor 8, which is estimated by the load estimator 11, velocity and acceleration transducers 12 based on the acceleration α detected by the Coulomb friction load T _LC and the load becomes inertia (inertia This is the load torque due to the fluctuation of the moment, and is hereinafter divided into J _L ).

Incidentally, when the load of the electric motor 8 is the Coulomb friction load T _LC and the load inertia moment J _L , the speed ω and the load torque T _L of the electric motor 8 are as shown in FIGS. 3A and 3B, respectively. It changes with. As is apparent from the figure, the load torque T _L of the electric motor 8 becomes T _L1 and T _L2 in acceleration and steady state, respectively. The load torque T _L2 in the steady state means the Coulomb friction load T _LC .
Therefore, a load separator 13 obtains the load torque T _L at the end of the acceleration time t _r after the electric motor 8 (= T _L2) as Coulomb friction load T _LC.

On the other hand, during acceleration in which the load torque T _L is T _L1 ,
T _L1 = J _L α + T _L2 = J _L α + T _LC (1)
Therefore, the load inertia moment J _L is
J _L = (T _L1 −T _LC ) / α (2)
It is expressed.
Therefore, the load separator 13 is based on the load torque T _L (= T _L1 ) during acceleration, the Coulomb friction load T _LC obtained as described above, and the acceleration α during acceleration (2). The calculation of the equation is executed to obtain the load inertia moment J _L.
The coulomb friction load T _LC and the load inertia moment J _L are separated from the load torque T _L estimated by the load estimator 11 as described above. The load separator 13 calculates, for example, a deviation Δω _m ^err (see FIG. 3) between a predetermined maximum speed ω _max and an actual speed ω _m of the electric motor 8, and the deviation Δω _m ^err falls within a predetermined minute range. Time t _r is determined as the end of acceleration, that is, the start of steady state.

The speed command switching unit 15 determines the switching timing of the selector switch element 16 based on the target position θ _m ^ref , the actual position θ _m of the electric motor 8 and a second reference value Δθ _m2 ^err-s described later, and the timing The selector switch element 16 is switched by The switch element 16 is provided for selectively adding the output of the position controller 2 and the output of the speed command generator 14 to the input of the speed controller 3.

Here, description will be given first reference value [Delta] [theta] _m1 ^err-s and the second reference value Δθ _m2 ^err-s shown in FIG. 2 (a).
Speed command change time t ₂ in FIG. 2, which means the time of starting the deceleration of the motor 8. Since this deceleration start time varies depending on the target position θ _m ^{ref of} the electric motor 8, the Coulomb friction load acting on the electric motor 8, and the moment of inertia, it cannot be predicted.
Therefore, in this embodiment, the first reference value [Delta] [theta] _m1 ^err-s calculated, the speed command change point position deviation by comparing the first reference value [Delta] [theta] _m1 ^err-s of the electric motor 8 t ₂ That is, the deceleration start timing of the electric motor 8 is determined.

ただし、ω_m：電動機の実速度
ｋ_t：電動機のトルク係数
Ｊ_M：電動機の慣性モーメント
Ｊ_L：負荷となる慣性モーメント
i_torque：最大トルクを出力するための電動機のトルク分電流
Ｔ_LC：電動機に対するクーロン摩擦負荷 The first reference value Δθ _m1 ^err-s corresponds to the area of the velocity pattern shown in FIG. 2B in the areas t _{2 to} t ₃ and can be calculated based on the following equation.

Where ω _{m is} the actual speed of the motor
k _t : Torque coefficient of the motor
J _M : Moment of inertia of the motor
J _L : Moment of inertia
i _torque ： The torque component current of the motor to output the maximum torque
T _LC : Coulomb friction load on the motor

On the other hand, the second reference value Δθ _m2 ^err-s is fixedly set to a minute position deviation value that can be considered that the electric motor 8 has almost reached the target position θ _m ^ref . The second reference value Δθ _m2 ^err-s is smaller than the first reference value Δθ _m1 ^err-s .

Hereinafter, a positioning control method using the positioning control device according to this embodiment will be described.
The speed command changer 15 takes a deviation between the target position θ _m ^ref and the actual position θ _m of the electric motor 8, and compares this position deviation with the second reference value Δθ _m2 ^err-s . If the position deviation is equal to or greater than the second reference value Δθ _m2 ^err-s, it is determined that the motor 8 has not yet reached the vicinity of the target position θ _m ^ref , and the changeover switch element 16 is as shown in FIG. To the b side. Thereby, the speed command generated by the speed command generator 14 is selected as the speed command.

On the other hand, the speed command generator 14 calculates the position deviation and compares the position deviation with the first reference value Δθ _m1 ^err-s . The speed command generator 14 obtains the first reference value Δθ _m1 ^err-s and the actual speed ω _m of the motor 8 given from the position / speed converter 10 and the coulomb given from the load separator 13. moment of inertia which is a frictional load torque T _LC and the load (variation of moment of inertia) on the basis of the J _L executes computation of the above equation (3).

When the positioning is started, the position deviation is equal to or greater than the second reference value Δθ _m2 ^err-s . Therefore, the speed command generator 14 generates a speed command that indicates the allowable maximum speed (rated speed) ω _max of the electric motor 8. This speed command is input as a speed command ω _m ^ref to the speed controller 3 through the switch 16 connected to the contact b side at the present time.
Thereby, a steep instruction is given to the electric motor 8 to shift from the stopped state to the allowable maximum speed ω _max , and an infinite driving current tends to flow. However, the electric motor 8 is driven so that the allowable maximum current (maximum torque component current) i _torque flows by the action of the current limiter provided in the current controller 4 and is accelerated toward the allowable maximum speed ω _max. The

Until the speed command generator 14 determines that the positional deviation of the electric motor 8 has reached the second reference value Δθ _m2 ^err-s , that is, in the region (t ₀ <t ≦ t ₁ ), A speed command indicating the maximum allowable speed (rated speed) ω _max is continuously generated.
Therefore, in the example of FIG. 2, the electric motor 8 is accelerated to the maximum speed ω _max at the time point t ₂ , and thereafter, until the position deviation decreases to the first reference value Δθ _m1 ^err-s , that is, the region ( This maximum speed ω _max is maintained during the period of t ₁ <t ≦ t ₂ ). The current i in the region (t ₁ <t ≦ t ₂ ) is smaller than i _torque .

In general, the speed controller 3 includes a compensator (for example, a PI compensator) including an integrator for eliminating a steady-state deviation. Therefore, a speed command that changes stepwise as shown in FIG. 2D, that is, a speed that suddenly changes from zero to ω _max at time t ₀ and rapidly changes from ω _max to zero at time t _2. If you enter a command to the speed controller 3, t _0, t ₁ at the time, resulting in so-called windup. That is, the response may become unstable or vibrated due to overshoot or the like.

  Therefore, in this embodiment, the speed controller 3 is provided with an anti-windup function to avoid the windup phenomenon. Note that the anti-windup function can be obtained by using well-known means such as a state observer, for example, and the description thereof is omitted here. According to the speed controller 3 having the antiwindup function, the speed of the electric motor 8 can be controlled according to an ideal speed pattern as shown in FIG.

As shown in FIG. 2D, the speed command generator 14 generates a speed command instructing zero speed at time t ₂ when the positional deviation of the electric motor 8 is lower than the first reference value Δθ _m1 ^err-s. . However, even if this speed command is generated, the actual speed ω _m of the electric motor 8 does not instantaneously drop to zero. That is, the electric motor 8 descends while drawing a locus as shown in FIG. 2B while being driven by the current −i _torque that generates the maximum deceleration torque, and settles to zero.

When the positional deviation of the electric motor 8 is lower than the second reference value Δθ _m2 ^err-s , that is, when the time t ₃ has elapsed from the start of the control, the speed command switching device 15 connects the switch element 16 to the terminal a side. Switch to and connect.
As a result, the speed controller 3 is given a speed command corresponding to the output of the position controller 2, that is, the position deviation of the electric motor 8, so that a minute position deviation smaller than the second reference value Δθ _m2 ^err-s can be obtained. The electric motor 8 is driven so as to disappear, and the electric motor 8 is positioned at the target position θ _m ^ref .

In the above embodiment, although obtained by converting the output of the position detector 9 actual speed omega _m of the electric motor 8, be directly detected by an appropriate speed detector said actual speed omega _m good. Further, in the above embodiment, the load torque due to the fluctuation of the Coulomb friction load torque and the moment of inertia acting on the electric motor 8 is estimated by the load estimator using the disturbance observer. May be detected directly.

As is clear from the above description, according to the positioning control method and apparatus for an electric motor according to this embodiment, the electric motor can be positioned at high speed according to an ideal speed pattern only by giving a target position.
That is, as in the prior art, when trying to achieve the ideal speed pattern by commanding the target position by the output pulse of the oscillator, along with the load fluctuation due to the fluctuation of the target position, the Coulomb friction load torque, and the moment of inertia, Although it takes time to readjust the output form of the command pulse, according to the above embodiment, the speed command for high-speed positioning adapted to the target position and the load is self-generated, so that the above trouble is unnecessary. Become.
Moreover, conventionally, since the speed command is formed based on the output pulse of the oscillator accumulated in the deviation counter, a delay in control occurs due to the time until the pulse accumulates in the deviation counter. According to the embodiment, since the pulse oscillator and the deviation counter are unnecessary, the controllability is improved.

It is a block diagram which shows an example of the high-speed positioning device of the electric motor which concerns on this invention. (A), (b), and (c) are graphs each showing an example of a change pattern of an ideal position, speed, and torque component current of the motor when positioning the motor in the shortest time, respectively (d ) Is a graph showing a speed command for obtaining the ideal speed pattern of (b). (A) And (b) is a graph which shows the change mode of the speed and load torque of this motor when the load of a motor is a Coulomb friction load and a load inertia moment, respectively. It is a block diagram which shows the structural example of the positioning device of the conventional motor. (A), (b), and (c) are graphs showing examples of ideal torque current, speed, and position change patterns of the motor when the motor is positioned in the shortest time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Target position input device 2 Position controller 3 Speed controller 4 Current controller 6 Inverter 7 Current detector 8 Electric motor 9 Position detector 10 Position / speed converter 11 Load estimator 12 Speed / acceleration converter 13 Load separator 14 Speed command generator 15 Speed command changer

Claims (6)

Detecting a position deviation of the electric motor;
Comparing the position deviation with a first reference value and a second reference value smaller than the reference value, and when the position deviation is greater than or equal to the first reference value, a speed command that indicates an allowable maximum speed of the motor A speed command indicating zero speed when the position deviation is greater than or equal to the second reference value and smaller than the first reference value, and the position deviation when the position deviation is smaller than the second reference value. Each generating a speed command indicating the corresponding speed;
Driving the electric motor so that the speed of the electric motor becomes a speed corresponding to the speed command,
A high-speed positioning method for an electric motor, wherein the first reference value is set based on the following equation.

Where ω _{m is} the actual speed of the motor
k _t : Torque coefficient of the motor
J _M : Moment of inertia of the motor
J _L : Moment of inertia
i _torque ： The torque component current of the motor to output the maximum torque
T _LC : Coulomb friction load on the motor Load become the moment of inertia, fast positioning method of an electric motor according to claim 1, characterized in that estimated based on the driving current, velocity and acceleration of said motor of said electric motor.   The high-speed positioning method for an electric motor according to claim 1, further comprising a step of performing anti-windup compensation on the speed command. Deviation detecting means for detecting the positional deviation of the electric motor;
Comparing the position deviation with a first reference value and a second reference value smaller than the reference value, and when the position deviation is greater than or equal to the first reference value, a speed command that indicates an allowable maximum speed of the motor A speed command indicating zero speed when the position deviation is greater than or equal to the second reference value and smaller than the first reference value, and the position deviation when the position deviation is smaller than the second reference value. Speed command generating means for generating speed commands for instructing corresponding speeds, and
Drive means for driving the electric motor so that the speed of the electric motor becomes a speed corresponding to the speed command;
The high-speed positioning apparatus for an electric motor, wherein the first reference value is set based on the following formula.

Where ω _{m is} the actual speed of the motor
k _t : Torque coefficient of the motor
J _M : Moment of inertia of the motor
J _L : Moment of inertia
i _torque ： The torque component current of the motor to output the maximum torque
T _LC : Coulomb friction load on the motor Drive current of the motor, and means for detecting the velocity and acceleration, the driving current, based on the speed and acceleration, in claim 4, characterized in that it comprises a means for estimating the moment of inertia of the load of the motor A high-speed positioning device for an electric motor as described.   5. The high-speed positioning apparatus for an electric motor according to claim 4, further comprising compensation means for applying anti-windup compensation to the speed command.

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