JP2003339193A - Driver of stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driver of a stepping motor in which the motor characteristics are not required to be grasped previously, the load torque current is not required to be detected and stabilized control can be realized up to a high speed rotational region through a simple and inexpensive system arrange ment. <P>SOLUTION: A positional deviation δ of an angle detection signal θ<SB>f</SB>indicative of the rotational angle of the rotor from a command angle θ* is calculated and compared with a specified value. A lead angle controller 20 outputs the command angle θ* if the positional deviation δ is not larger than the specified value, otherwise outputs a value obtained by adding a fixed value (90°), a rotational angular frequency ω<SB>re</SB>multiplied by a specified coefficient k<SB>ω</SB>, and a value obtained by multiplying the product of the positional deviation δ and the rotational angular frequency ω<SB>re</SB>by a coefficient k<SB>r</SB>to the angle detection signal θ. Phase of a voltage being applied to the motor is controlled by the output from the lead angle controller 20, i.e., a correction command angle θ<SB>r</SB>. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor drive device for controlling the rotor rotation angle and rotor speed of a stepping motor.

[0002]

[Prior art]

[Non-Patent Document] IEE Proc.-Electr. Power Appl., Vol.14
2, No.1, January 1995 Motors are required to be able to rotate over a wide range with low vibration as the equipment becomes highly functional.However, stepping motors apply a current pulse to each winding from the outside every time a command pulse is applied. Since it rotates by switching to, there is a problem in that vibration and step-out occur due to switching of energization conditions. In order to reduce the vibration, a micro-step drive in which a winding current is smoothly changed using a pulse width modulation type (hereinafter referred to as PWM) inverter is generally used as the vibration reducing measure. Further, in order to prevent step-out, a control system has been proposed which includes an angle detector for detecting the rotor rotation angle and selects an appropriate excitation condition at the step-out limit.

In order to prevent out-of-step, for example, a conventional example described in the non-patent document shown in FIG. 4 (hereinafter referred to as a first conventional example).
, The method of controlling the phase angle of the motor applied voltage,
That is, advance control can be considered. In the first conventional example shown in the drawing, the detection unit 211 receives a command angle θ ^* given from the outside and a rotor angle detection signal θ _f which is an output of the encoder 240 and generates a detection signal. The speed determination unit 214 receives the output of the detection unit 211 and determines the speed. The position deviation counting unit 215 receives the output of the detection unit 211 and calculates the position deviation. The control unit 212 uses the detection unit 21.
The control algorithm is executed by receiving 1 and the outputs of the speed determination unit 214 and the position deviation counting unit 215. The pulse signal generator 213 receives the output of the controller 212 and generates a pulse signal. The torque signal generator 220 receives the pulse signal from the pulse signal generator 213 and controls the stepping motor power unit 230. In the first conventional example, an encoder is used to drive a stepping motor in open loop control in a normal state, and an applied voltage is applied according to a value of a position deviation which is a difference between a pulse command and an actual position of the motor by the encoder. It is possible to change the phase of to avoid step-out and realize high-speed rotation. In addition, in the first conventional example, the operation of advancing the phase of the motor applied voltage beyond the command position, that is, the advance, is expected in consideration of the fact that the motor exciting current is delayed with respect to the applied voltage due to the winding inductance. A stable control system is realized with a simple configuration by performing angle control. The phase of the applied voltage that has been advanced,
That is, the advance value is determined by using the position deviation and the motor rotation speed as input values, but for a plurality of advance values, the relationship between the motor rotation speed and the generated torque is experimentally determined and determined. Elements that absorb changes in specifications and changes in load torque are not specified. Therefore, it is necessary to measure appropriate conditions for each motor specification.

A stepping motor, which is a kind of synchronous motor, can determine an appropriate advance angle value γ from the voltage equation by the equation (1).

[0005]

[Equation 1] Here, γ is the advance angle value, ω _re is the rotation angle (electrical angle) frequency (current fundamental frequency) of the motor, L is the motor winding inductance, R is the motor winding resistance, Z is the motor winding impedance, and i _q the q-axis component of the motor winding current, V is the voltage applied to the motor, E _{e mf} is a speed electromotive force. Below, the derivation process of equation (1) is shown, and the significance of advance control is described. The magnitude of the voltage applied to the motor is V, and its d-axis and q-axis components are v _d and v _q . Further, when the magnitude of the motor winding current is I and the d-axis and q-axis components thereof are _id and _iq , the relationships of the expressions (2) and (3) are established.

[0006]

[Equation 2]

[0007]

[Equation 3] Regarding v _d and v _q , the voltage equation of the motor is as shown in equation (4).

[0008]

[Equation 4] Where p is the differential operator, L_dIs the winding inductance
d-axis component, L_qIs the q-axis component of the winding inductance, and R is
Winding resistance, ω_reIs the rotational angular frequency of the motor, Φ _mIs moo
Represents magnetic flux. Here, the steady state at high speed rotation
Think, pL_d= PL_q= 0, R << ω_rePut it as L (4)
By approximating the equations, equations (5) and (6) are obtained.

[0009]

[Equation 5]

[0010]

[Equation 6] Equations (5) and (6) are substituted into equations (2) and (3) to obtain equation (7).

[0011]

[Equation 7] In equation (7), the normal power supply voltage V_oIs constant, so
The maximum applied voltage of the data is usually V_oIt becomes the following. Note that ω
_reΦ_mIs the speed electromotive force E_emfIs. In equation (7)
Ω_reΦ_m> V_oMotor internal voltage in case of
The relationship is shown in FIG. In FIG. 6, the motor applied voltage V
_oIs the reactance drop ω in the d-axis direction_reL_qi_qAnd
Vector AC and the reactance drop ω in the q-axis direction_re
L _di_dVector CB and velocity electromotive force in the q-axis direction
Backward component of −ω_reΦ_m= -E_emfVector O which is
It becomes a combined vector OB with A. Circle P has radius V _oof
Indicates a circle. FIG. 6 shows that the phase of the motor applied voltage can be controlled.
And the speed electromotive force E _emfIs the power supply voltage V_oRotation over
It shows that it can be controlled up to a number.

In equation (1), the steady state at high speed is considered, and equation (8) is obtained by approximating equation (4) with pL _d = pL _q = 0.

[0013]

[Equation 8] When the q-axis current i _q is obtained from the equation (8), the equation (9) is obtained.

[0014]

[Equation 9] here,

[0015]

[Equation 10]

[0016]

[Equation 11]

[0017]

[Equation 12]

[0018]

[Equation 13]

[0019]

[Equation 14] Suppose As the motor torque T is proportional to i _q, if you put a proportionality constant and kt,

[Equation 15] Therefore, the expression (16) representing the advance value γ, that is, the expression (1) is obtained.

[0020]

[Equation 16] Here, since the motor winding resistance R and the motor winding inductance L can be known values, the advance value γ can be determined from the q-axis current i _q and the rotation angular frequency ω _{re of the} motor. it can. By giving the advance value γ according to the equation (1), the stepping motor can maintain a state in which it is balanced with the load torque at any rotation speed. That is, by controlling the advance value γ, the rotation can be controlled up to the high speed range without stepping out the stepping motor. Figure 5
It is a block diagram which shows the drive device of the stepping motor of the 2nd prior art example. As shown in the figure, the calculator 19 converts the command angle θ ^* applied to the angle command input terminal 10 and the signal of the encoder 90 connected to the rotor shaft of the stepping motor 80 into the rotation angle of the rotor by the angle calculator 91. The advance angle γ is calculated from the converted angle detection signal θ _f using the equation (1). The current detectors 55 and 56 detect the motor winding currents i _αf and i _βf . The coordinate converter 61 converts the motor winding currents i _αf and i _{β f} into the current value i in the rotating coordinate system.
Convert to _df and i _qf . Further, the adder 51 uses the d-axis command current value i _d ^* applied to the d-axis current command input terminal 31 ^.
And the rotational coordinate system current value i _df , that is, the current deviation is obtained. Similarly, the adder 52 uses the q-axis current command input terminal 3
The difference between the q-axis command current value i _q ^* added to 2 and the rotating coordinate system current value i _qf , that is, the current deviation is obtained. The current controllers 53 and 54 amplify the outputs of the adders 51 and 52, that is, the current deviations, respectively. The coordinate converter 62 is a calculator 19
Then, it receives the outputs of the current controllers 53 and 54 and converts from the rotating coordinate system to the fixed coordinate system. In addition, the PWM inverter 7
0 receives the output of the coordinate converter 62 and applies a predetermined voltage to the stepping motor 80 to rotate the stepping motor 80. As described above, in the second conventional example shown in FIG. 5, it is possible to perform the advance angle control using the equation (1) by the calculator 19, but the advance angle value γ according to the change of the load torque. Since it is necessary to detect the load torque or the q-axis current i _q required to generate the load torque, that is, the load torque current, there is a problem in that the advance value derivation calculation becomes complicated and the cost becomes high. In particular, a system using a microcomputer has a problem that it takes a long time to derive an advance angle value.

[0021]

As described above, in the first conventional example in which the advance angle control is performed, it is necessary to investigate the motor characteristics in advance in order to deal with the constant change of the stepping motor. In addition, in the second conventional example, (1)
Since the advance value γ is controlled according to the change of the load torque current, which is the q-axis current i _q in the equation, the load torque current needs to be detected, and the system configuration becomes complicated and the cost increases. there were. The present invention solves the above problem and does not need to investigate and grasp the motor characteristics in advance,
Another object of the present invention is to provide a drive device for a stepping motor that does not require detection of load torque current, has a simple system configuration, is inexpensive, and can stably realize control up to a high-speed rotation range. .

[0022]

To achieve the above object, a stepping motor driving device of the present invention is obtained from the outside in a stepping motor driving device for controlling the phase of a motor applied voltage with respect to a rotor rotation angle. The position deviation, which is the difference between the command angle and the rotor rotation angle, is calculated, and the position deviation is compared with a predetermined value.If the position deviation is less than or equal to the predetermined value, the command angle is output and the position If the deviation exceeds the predetermined value, it is obtained by multiplying the rotor rotation angle by a fixed value, a value obtained by multiplying the motor rotation angular frequency by a predetermined coefficient, and the position deviation by the rotation angular frequency. It is characterized in that it comprises an advance angle control means for outputting a value obtained by adding a value obtained by multiplying the above value with a coefficient, and the phase of the motor applied voltage is controlled by the output of the advance angle control means.

In this case, a value obtained by differentiating the angle detection signal representing the rotor rotation angle detected by the angle calculating means is used as the rotation angular frequency.

Alternatively, a value obtained by differentiating the command angle is used as the rotation angular frequency.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 7A is a graph showing the relationship between the rotational angular frequency ω _{re of the} motor and the advance value γ, which is represented by the equation (1). In the figure, a-1 is the sum of the values of the first term and the second term of the equation (1), a-2 is the value of the first term of the equation (1), and a-3 is the second term of the equation (1). The value of each is shown. As shown in the figure, the first term of the equation (1) is the phase angle related to the impedance of the motor, and the rotational angular frequency ω _{re of the} motor is
Asymptotically approaches 90 ° with increasing. Also, the second of the equation (1)
The term changes as the rotational angular frequency ω _re of the motor and the q-axis current (load torque current) i _q increase or decrease. On the other hand, as is well known, the generated torque T when the motor exciting current is constant can be approximated by the equation (17).

[0026]

[Equation 17] However, T _m is the maximum static torque, δ is the load angle, and when the reference is the d axis, δ corresponds to the position deviation that is the difference between the command angle and the rotor rotation angle. When the rotational angular frequency ω _re is relatively small and the positional deviation is also small, it can be considered that the motor torque is generated according to the equation (17). Therefore, when the positional deviation δ is equal to or less than the predetermined value, the advance angle control is not performed and the command angle is used as it is as the phase of the motor applied voltage. For example, 90 ° is used as the predetermined value. When the position deviation δ exceeds the predetermined value, the value of the first term in the equation (1) gradually approaches a constant value, so a fixed value that is a constant value is used as the value of the first term. As the fixed value, it is desirable to use a value of 90 ° or a value in the vicinity thereof, in view of the characteristic of the trigonometric function. FIG. 7B is a graph showing the relationship between the value of the first term of the equation (1) approximated in this way and the rotational angular frequency ω _re of the motor. In the figure, b-1 is a strict value of the first term of the equation (1), b-2 is a value obtained by substituting the first term of the equation (1) with a command angle, and b-3 is the first term of the equation (1). Is a range in which the command angle is substituted, and b-4 is a range in which the first term in the equation (1) is approximated by a fixed value. Further, the second term of the equation (1) is, as a first approximation, the rotation angular frequency ω of the motor.
It can be approximated by a linear expression of _re , and the rotation angular frequency ω
It is practically possible to use a value obtained by multiplying _re by an appropriate coefficient as the value of the second term, and this value is called a speed compensation value.
Further, as shown in FIG. 7A, the second term of the equation (1) is
Rotational angular frequency ω _re and q-axis current (load torque current) i
_It changes with the increase and decrease of _q , and the gradient of the change increases rapidly with the increase of ω _re and the q-axis current (load torque current) i _q . On the other hand, the relationship between the generated torque T and the position deviation δ is (1
As shown in the equation 7), when δ ≦ 90 degrees, the torque change and the load angle (positional deviation δ) change with the same sign, and the positional deviation δ is expressed by the inverse sine function of the generated torque. You can Therefore, in order to reflect the change in the value of the second term of the equation (1) due to the rotational angular frequency ω _re and the q-axis current (load torque current) i _q , the position deviation δ and the rotational angular frequency ω
_By adding a value obtained by multiplying _re and a suitable coefficient to the value given by the above first-order approximation,
Further, it becomes possible to correct the advance value corresponding to the load change. The correction value thus obtained is called a deviation compensation value. Figure 7
(C) is a graph showing the relationship between the value of the second term of the equation (1) and the rotational angular frequency ω _re of the motor approximated in this way. In the figure, c-1 is the exact value of the second term of the equation (1), c-2 is the total value of the speed compensation value and the deviation compensation value, and c
-3 is a deviation compensation value, and c-4 is a speed compensation value. FIG. 1 is a block diagram showing a driving device of a stepping motor according to the present invention. The stepping motor 80 shown in the figure rotates by applying a predetermined voltage from the PWM inverter 70 to the motor winding. Stepping motor 80
Winding current values i _αf , i _{β f in} the α-β fixed coordinate system of
Is detected by the current detectors 55 and 56 and sent to the first coordinate converter 61. The angle calculator 91 is an encoder 90.
From this, a signal relating to the position of the rotor (not shown) of the stepping motor 80 is received, and an angle detection signal θ _f representing the rotor rotation angle is calculated. The encoder 90 and the angle calculator 91 form an angle calculator. The first coordinate converter 61 converts the winding current values i _αf and i _βf into dq
It is converted into a d-axis winding current value i _df and a q-axis winding current value i _qf in the rotating coordinate axis system. On the other hand, the d-axis command current value i
_{The d} ^* and q-axis command current values i _q ^* are applied to the d-axis command current input terminal 31 and the q-axis command current input terminal 32, respectively. The current controller 53 amplifies the difference between the d-axis command current value i _{d *} and the d-axis winding current value i _df , that is, the current deviation, and sends it to the second coordinate converter 62. Similarly, the current controller 54
The difference between the axis command current value i _q ^* and the d-axis winding current value i _df , that is, the current deviation is amplified and sent to the second coordinate converter 62. The second coordinate converter 62 converts the amplified d-axis current deviation and q-axis current deviation in the dq rotation coordinate axis system into values in the α-β fixed coordinate system, and in the α-β fixed coordinate system. It is sent to the PWM inverter 70 as a current control signal. The PWM inverter 70 generates a voltage based on the current control signal in the α-β fixed coordinate system and supplies it to the motor winding. The advance angle controller (advance angle control means) 20 has an angle detection signal θ _f indicating a command angle θ ^* and a rotor rotation angle applied from the outside.
A correction command angle θ _r is generated based on the difference between Details of the advance angle controller 20 will be described later. The first coordinate converter 61 and the second coordinate converter 62 use the correction command angle θ _r , which is the output of the advance angle controller 20, from the α-β fixed coordinate system to the dq rotary coordinate axis system. , Or vice versa. FIG. 2 is an advance angle controller 2 in the first embodiment of the driving apparatus for a stepping motor according to the present invention.
It is a block diagram which shows the detail of 0. In the figure, the subtractor 26 subtracts the angle detection signal θ _f from the command angle θ ^* to calculate the position deviation δ. The determiner 24 generates a switching signal depending on whether the positional deviation δ (electrical angle) is less than 90 ° or 90 ° or more. When the position deviation δ (electrical angle) is less than 90 °, the switch 30 responds to the switch signal so that the switch outputs the command angle θ ^* as the correction command angle θ _r without any change. Connect to ^* side. Further, when the position deviation δ (electrical angle) is 90 ° or more in response to the switching signal, the switch 30 performs the correction command angle θ according to the present invention for performing advance control.
_The switch is connected to the adder 27 side so as to output _r . The differentiator 23 differentiates the angle detection signal θ _f to calculate the rotational angular frequency ω _re of the rotor. The speed compensator 29 is
The rotational angular frequency ω _re is multiplied by a predetermined coefficient k _ω to calculate the speed compensation value. The multiplier 22 multiplies the position deviation δ by the rotation angular frequency ω _re . The deviation compensator 28 detects the position deviation δ.
_Is multiplied by the rotational angular frequency ω _re to multiply the value obtained by the coefficient k _R to calculate the deviation compensation value. The adder 27 adds the fixed value (for example, 90 °) supplied from the fixed value generator 21, the speed compensation value, and the deviation compensation value to the angle detection signal θ _f , which is the rotor rotation angle, to calculate the position. The correction command angle θ _r when the deviation δ (electrical angle) is 90 ° or more is output.
The approximation of the first term of the equation (1) is realized by the switching operation of the phase angle control of the motor applied voltage according to the switching signal of the determiner 24, and the approximation of the first term of the equation (1) is realized by the speed compensation value and the deviation compensation value. A binomial approximation is implemented. According to such a stepping motor drive device of the present invention, the motor rotation can be stably maintained up to a high speed region without stepping out in response to changes in speed and load torque. Further, since the phase of the voltage applied to the stepping motor is controlled, a position / speed controller is not required, and the number of adjusting elements is reduced as compared with the conventional AC servomotor.

FIG. 3 is a block diagram showing an advance angle controller in the second embodiment of the stepping motor drive device according to the present invention. In the first embodiment, the rotation angle frequency ω _{re of the} rotor is differentiated by differentiating the angle detection signal θ _f.
However, in the second embodiment, the command angle θ ^* is differentiated to calculate the rotation angular frequency ω _re . The procedure is the same as that of the first embodiment except that the rotation angle frequency ω _re is calculated by differentiating the command angle θ ^* . Also in this case, it is possible to stably maintain the motor rotation even in the high speed region without stepping out, and to perform stable advance control.

In the embodiment of the present invention, the encoder is used to detect the rotational angular frequency.
A sensor such as a resolver having equivalent performance may be used. Further, the sensor may not be directly connected to the motor shaft. Further, although the current is controlled by using the current detector, the present invention can be applied to a voltage drive type driving device. Further, although the two-phase stepping motor has been described in detail in the above-described embodiment, the present invention can be applied to a multi-phase stepping motor. Further, the advance angle control means can be realized by a microprocessor.

[0029]

According to the present invention, in a drive device for a stepping motor for controlling the phase of a voltage applied to a motor with respect to a rotor rotation angle, a position deviation which is a difference between a command angle obtained from the outside and a rotor rotation angle is calculated. Then, the position deviation is compared with a predetermined value, and if the position deviation is less than a predetermined value, the command angle is output, and if the position deviation exceeds the predetermined value, the rotor rotation angle is set to a fixed value and the motor The motor applied by the output of the advance angle control means for outputting a value obtained by adding a value obtained by multiplying the rotation angular frequency of the above by a predetermined coefficient and a value obtained by multiplying the position deviation by the rotation angular frequency by the coefficient Since the voltage phase is controlled, the proper advance value of the stepping motor can be determined with a simple operation to control the applied voltage phase, and it is not necessary to investigate and grasp the motor characteristics in advance. Detect It is not necessary, the system configuration is simple, inexpensive, and capable of stably realizing a control to a high-speed rotation region, it is possible to provide a driving apparatus of the stepping motor. Since a value obtained by differentiating the angle detection signal detected by the angle calculation means is used as the rotation angular frequency, it is not necessary to separately provide a device for detecting the rotation angular frequency or the rotation speed of the rotor. Further, when the value obtained by differentiating the command angle is used as the rotation angular frequency, it is possible to realize stable control which is less affected by the vibration of the motor. Further, even when the calculation in the driving device of the stepping motor of the present invention is processed by the computer software, the processing contents are simplified, so that the advance angle control is performed by an inexpensive processing means without requiring an expensive and highly functional CPU. It is possible to realize the function.

[Brief description of drawings]

FIG. 1 is a block diagram showing a driving device of a stepping motor according to the present invention.

FIG. 2 is a block diagram showing an advance angle controller in the first embodiment of the stepping motor drive device according to the present invention.

FIG. 3 is a block diagram showing an advance angle controller in a second embodiment of a stepping motor drive device according to the present invention.

FIG. 4 is a block diagram showing a driving device of a stepping motor in a first conventional example.

FIG. 5 is a block diagram showing a driving device of a stepping motor in a second conventional example.

FIG. 6 is a diagram for explaining a relationship between voltages inside a motor.

FIG. 7 is a graph showing a relationship between a rotation angular frequency and an advance value.

[Explanation of symbols]

10 ... Angle command input terminal 20 ... Advance controller 21 ... Fixed value generator 22 ... Multiplier 23 ... Differentiator 24 ... Judgment device 26 ... Subtractor 27 ... Adder 28 ... Deviation compensator 29 ... Speed compensator 30 ... Switch 31 ... d-axis command current input terminal 32 ... q-axis command current input terminal 51, 52 ... Adder 53, 54 ... Current controller 54 ... Current controller 55, 56 ... Current detector 61 ... First coordinate converter 62 ... Second coordinate converter 70 ... PWM inverter 80 ... Stepping motor 90 ... Encoder 91 ... Angle calculator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukinari Takahashi             Gunma Prefecture Kiryu City Aioi 3-93 Address Nippon Sir             Bo Institute of Research (72) Inventor Hiroaki Taka             Gunma Prefecture Kiryu City Aioi 3-93 Address Nippon Sir             Bo Institute of Research F-term (reference) 5H580 BB06 FA04 FA10 FA14 FA24                       FC10 HH02 HH39 JJ02

Claims (3)

[Claims] 1. A stepping motor drive device for controlling a phase of a motor applied voltage with respect to a rotor rotation angle, wherein a position deviation which is a difference between a command angle obtained from the outside and the rotor rotation angle is calculated, and the position deviation is calculated. If the position deviation is less than or equal to the predetermined value, the command angle is output.If the position deviation exceeds the predetermined value, the rotor rotation angle is set to a fixed value. , Advance value control means for outputting a value obtained by adding a value obtained by multiplying the rotational angular frequency of the motor by a predetermined coefficient and a value obtained by multiplying the positional deviation by the rotational angular frequency by a coefficient A stepping motor drive device, comprising: controlling the phase of the motor applied voltage by the output of the advance angle control means. 2. The stepping motor drive device according to claim 1, wherein a value obtained by differentiating an angle detection signal representing the rotor rotation angle detected by the angle calculation means is used as the rotation angular frequency. 3. The stepping motor drive device according to claim 1, wherein a value obtained by differentiating the command angle is used as the rotational angular frequency.