JPH06343294A - Drive controller of stepping motor - Google Patents

Abstract

PURPOSE:To provide a stepping motor drive controller which was so corrected that the rotation of each one pulse may be uniform in microstep driving of a stepping motor. CONSTITUTION:This equipment is provided with an up/down counter 1 which assigns a rotor position of a motor, ROMs 2a, 2b, which correct exciting signals in accordance with a characteristic of a stepping motor and store data which leads the corrected data with the help of an electric angle of the motor and data which lags the corrected data, a signal generator 5 which generates an excitation switching signal having the frequency that the rotor of the motor cannot follow or above, and exciting current controlling sections 3a, 3b, which select lead phases and lag phases of the ROMs 2a, 2b by means of the excitation switching signal of the signal generator 5, and read out from the ROMs an exciting signal corresponding to a counter output value of the up/down counter, and convert the read-out excitation signal data to exciting current of each phase of the stepping motor 4.

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 control device for driving a stepping motor in microsteps, and more particularly, to the position of a stable point by finely changing the magnitude of the excitation signal for each phase of the stepping motor. The present invention relates to a drive control device for a stepping motor in which the excitation signal is corrected in accordance with the motor characteristics so that the step angle is made finer and the rotation amount for each pulse becomes uniform. is there.

[0002]

2. Description of the Related Art In recent years, a microstep drive of a stepping motor can be controlled in an open loop, and a servo mechanism can be simply and highly accurately configured without using a feedback element such as an encoder or a potentiometer. Is often used as a magnetic head drive source.

A conventional drive control device for a stepping motor will be described below. FIG. 5 shows the configuration of a conventional drive control device for a stepping motor. In FIG. 5, 1 is an up / down counter that counts up or down the clock pulse CLK according to the rotation direction signal UD / DOWN, 2a and 2b are ROMs storing amplitude data of sine wave and cosine wave, and 31a and 31b are up and down. Each ROM uses the output of counter 1 as address data
D / A converters that convert the amplitude data read from 2a and 2b into analog signals, and 32a and 32b are the D
A / A converter drives a stepping motor according to an output analog signal of the A / A converter.
An exciting current control unit including converters 31a and 31b and drive circuits 32a and 32b, 4 is a stepping motor, and 4 is a stepping motor.
Reference symbols a and 4b are stator coils of the stepping motor 4.

The operation of the drive control device for the stepping motor configured as described above will be described below. First, when the counting direction of the up / down counter 1 is set by the rotation direction signal UD / DOWN and the clock pulse CLK is input, the up / down counter 1 starts counting operation. As shown in FIG. 6, amplitude data of the sine wave and the cosine wave are sequentially read from the ROMs 2a and 2b using the count value of the up / down counter 1 as address data, and the D / A converter 31 of the exciting current control units 3a and 3b is read.
It is converted into an analog signal by a and 31b, and is input to the drive circuits 32a and 32b as an excitation signal. The drive circuit is
For example, the stator coils 4a and 4b of the stepping motor 4 are driven by constant current driving.

In the case of such a stepping motor driving device, it is known that the pitch accuracy for each step has an error cycle that is four times as large as one cycle (2π in electrical angle) of the stepping motor. . This cycle matches the cycle of the cogging torque of the static torque characteristic, and it is considered that this is mainly due to the characteristics inside the stepping motor. That is, the step angle cannot be made uniform in the microstep driving by the waveform of the sine wave and the cosine wave,
Since the rotation amount for each pulse becomes non-uniform, in order to realize highly accurate positioning, it is necessary to correct the magnitude of each phase excitation signal according to the characteristics of the stepping motor.

Therefore, for example, based on the static angle data for each pulse obtained by switching the excitation current in steps of sine wave and cosine wave, the rotation amount for each pulse becomes uniform, for example, as shown in FIG. It is considered to correct the excitation signal as shown in.

Further, when the pitch accuracy at each step differs depending on the rotation direction of the stepping motor, a forward rotation correction table and a reverse rotation correction table are provided, and independent excitation signal correction is performed during forward rotation and reverse rotation of the motor. It is considered to be performed (Japanese Patent Laid-Open Publication No. 1-218393).
1-218394).

[0008]

However, in the above conventional configuration, when independent excitation signal correction is performed during forward rotation and reverse rotation of the motor, when the hysteresis of the static angle accuracy during forward rotation and reverse rotation is large. During the switching between the normal rotation and the reverse rotation, there is a possibility that the position may be displaced due to the difference in data and the rotation axis may be skipped. Therefore, it is conceivable to switch the forward rotation excitation signal and the reverse rotation excitation signal when the two coincide with each other, but in this case, the excitation signal cannot be switched at any place, so that the pitch accuracy for each step can be smoothly changed. However, there is a problem in that it cannot be uniformly corrected.

The present invention solves the above-mentioned conventional problems. The stepping motor drive control can make the rotation amount uniform for each pulse and eliminate the hysteresis phenomenon regardless of the rotation direction of the stepping motor. The purpose is to provide a device.

[0010]

In order to achieve this object, the apparatus of the present invention finely changes the magnitude of each phase excitation signal of the stepping motor to gradually move the position of the stable point to obtain the step angle. With the miniaturization of 1
In a stepping motor micro-step drive control device that corrects the excitation signal according to the motor characteristics so that the rotation amount for each pulse becomes uniform, the motor rotor cannot follow the excitation position of the stepping motor. A high-frequency vibration component having a frequency equal to or higher than the frequency is added, and the central excitation position of the high-frequency vibration component is adjusted to the motor characteristic so that the rotation amount for each pulse becomes uniform.

[0011]

With this configuration, since the excitation position of the stepping motor vibrates at high frequency, high frequency vibration torque is generated in the rotor of the motor. If the maximum value of this high-frequency vibration torque is equal to or greater than the loss caused by friction of the motor,
Starting torque is sequentially generated in the motor rotor in the forward rotation direction and the reverse rotation direction, and the hysteresis phenomenon of the stepping motor can be eliminated. Further, since the central excitation position of the harmonic vibration component is adjusted to the motor characteristics so that the rotation amount for each pulse is uniform, the stepping motor can be driven with higher accuracy, regardless of the rotation direction. The rotation amount for each pulse can be made uniform.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. An up-down counter 1, ROMs 2a and 2b, exciting current control units 3a, 3b and D which are substantially the same as the conventional example shown in FIG.
/ A converters 31a and 31b, drive circuits 32a and 32
b, stepping motor 4, stator coils 4a, 4b
In a drive control device for a stepping motor including the above, a signal generator 5 for generating an excitation switching signal having a frequency equal to or higher than a frequency that cannot be followed by a rotor of the motor is provided, and the excitation signals are corrected in the ROMs 2a and 2b according to the characteristics of the motor. However, this correction data is different from the conventional example in that it includes data in which the phase is advanced by the electrical angle and data in which the phase is delayed.

The operation of the stepping motor drive control device constructed as described above will be described with reference to FIG. FIG. 2 shows that the rotation direction signal UD / DOWN is turned up (H) and the rotation direction signal UP / D is rotated for one period (2π in electrical angle) from the stationary state in the initial state.
The state of each part when the OWN is turned down (L) and one cycle (2π in electrical angle) is rotated in the reversing direction is shown.

First, the clock pulse CLK is not input and the count value of the up / down counter 1 is in the initial state of 0. Here, the up / down counter 1 has one cycle of the stepping motor (2π in electrical angle).
Is divided into 256 equal parts by microstep driving,
It is an 8-bit up / down counter that returns to zero at 256.

The signal generator 5 constantly generates an excitation switching signal SELECT having a frequency equal to or higher than the frequency that the rotor of the motor cannot follow.
Is generated, and the lead phase correction data and the lag phase correction data stored in the ROMs 2a and 2b are selected by this signal. That is, for example, as shown in FIG.
In the OMs 2a and 2b, the lead phase correction data is stored in the even address (the lowest address A0 = 0), and the lag phase correction data is stored in the odd address (the lowest address A0 =
1), and the excitation switching signal SELECT is stored in ROM
Input to the lowest address (A0) of 2a and 2b. RO
The count output of the up / down counter 1 is input to the upper addresses (A1 to A8) of M2a and 2b. By this address connection, the excitation with the correction data of the lead phase and the correction data of the lag phase are alternately performed with respect to the excitation position designated by the up / down counter 1, and high frequency vibration can be constantly applied. Due to the high frequency vibration at the excitation position, a high frequency vibration torque is generated in the stepping motor. When the high-frequency vibration torque exceeds the maximum frictional force of the motor, the starting torque acts to start the motor rotor and accelerate it, but since the rotor has inertia, it cannot follow the high-frequency vibration at the excitation position. It stops when the starting torque in the forward direction and the starting torque in the reverse direction are balanced.

Next, the clock pulse CLK is input,
When the up-down counter 1 starts the counting-up operation, the excitation position vibrates at high frequency and the rotation angle moves in the forward direction. Due to this movement of the excitation position, the high-frequency vibration torque becomes larger than the starting torque generated in the forward rotation direction, the equilibrium state collapses, the rotor accelerates in the forward rotation direction, and moves to the next equilibrium position. . By repeating this operation, the rotor of the stepping motor follows the movement of the excitation position due to the counting up operation of the up / down counter 1.

Even when the rotation direction signal UP / DOWN is inverted and the up / down counter 1 starts counting down, as in the case of counting up, the high frequency vibration torque is larger in the starting torque generated in the inversion direction. The equilibrium state collapses, the rotor accelerates in the reverse direction, and moves to the next equilibrium position. By repeating this operation, the rotor of the stepping motor follows the movement of the excitation position due to the counting down operation of the up / down counter 1.

The central excitation position at the electrical angle of the lead phase correction data and the lag phase correction data stored in the ROMs 2a and 2b is matched to the motor characteristics so that the rotation amount for each pulse is uniform. For example, the electrical angle is as shown in FIG. 4, and the one-step electrical angle for one step in the micro-step drive has a non-linear characteristic.

As described above, according to the present embodiment, a high-frequency vibration component having a frequency higher than that of the rotor of the motor cannot follow is added to the excitation position of the stepping motor, and the central excitation position of the high-frequency vibration component is every pulse. It has a configuration adapted to the motor characteristics so that the rotation amount of is uniform. When the maximum value of the high-frequency vibration torque generated by the high-frequency vibration component at the excitation position is made equal to or higher than the loss caused by the friction of the motor, the starting torque is sequentially generated in the forward and reverse directions of the motor rotor, and the stepping motor It is possible to eliminate the hysteresis phenomenon. Further, since the central excitation position of the harmonic vibration component is adjusted to the motor characteristics so that the rotation amount for each pulse is uniform, the stepping motor can be driven with higher accuracy, regardless of the rotation direction. The rotation amount for each pulse can be made uniform.

In this embodiment, in order to add a high frequency vibration component to the excitation position, one set of lead phase correction data and one set of lag phase correction data are provided and selected alternately. The high frequency vibration component may be added by sequentially selecting them using the correction data in which the phases of the sets are shifted. Further, the excitation current control units 3a and 3b are configured so that the D / A converters 31A and 31b are replaced by
A PWM control circuit that modulates input data with a pulse width time may be used.

[0022]

As described above, according to the present invention, a high-frequency vibration component having a frequency equal to or higher than the frequency that the rotor of the motor cannot follow is added to the excitation position of the stepping motor, and the central excitation position of the high-frequency vibration component is every pulse. Since the amount of rotation is matched to the motor characteristics so that the amount of rotation is uniform, the amount of rotation for each pulse is made uniform regardless of the rotation direction of the stepping motor, and high-precision positioning that can eliminate the hysteresis phenomenon is possible. It is possible to realize an excellent driving device for a stepping motor.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a drive control device for a stepping motor according to an embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the drive control device for the stepping motor in the embodiment.

FIG. 3 is a diagram showing corrected excitation data in a ROM of the drive control device for the stepping motor in the embodiment.

FIG. 4 is a diagram showing an electrical angle of an excitation position based on corrected excitation data of a ROM of the stepping motor drive controller in the embodiment.

FIG. 5 is a circuit diagram of a conventional drive control device for a stepping motor.

FIG. 6 is an R of a drive control device for a conventional stepping motor.
The figure which shows the excitation data of OM

FIG. 7 is a view showing R of a conventional drive control device for a stepping motor.
The figure which shows the excitation data which OM corrected.

[Explanation of symbols]

 1 Up-down counter 2a ROM 2b ROM 3a Excitation current control unit 3b Excitation current control unit 31a D / A converter 31b D / A converter 32a Drive circuit 32b Drive circuit 4 Stepping motor 4a Stator coil 4b Stator coil 5 Signal generator

Claims (1)

[Claims] 1. A stepping motor is provided with a stepwise motor in which the amplitude of each phase excitation signal is finely changed to gradually move the position of a stable point to make the step angle finer and to make the rotation amount per pulse uniform. As described above, in the stepping motor micro-step drive control device that corrects the excitation signal according to the motor characteristics, a high-frequency vibration component of a frequency higher than that of the motor rotor cannot follow is added to the excitation position of the stepping motor. A drive control device for a stepping motor, wherein the central excitation position of the high-frequency vibration component is adjusted to the motor characteristics so that the rotation amount for each pulse becomes uniform.