Drive controller for stepping motor

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a stepping motor drive control device that facilitates rotation of a stepping motor.

【0002】

[Conventional technology]

Conventionally, in order to smooth the rotation of the stepping motor, it has been known that in a stepping motor with 1-2 phase excitation, the sum of currents during 1-phase excitation and 2-phase excitation is made substantially equal to make the generated torque smooth. Has been done.

【0003】

[Problems to be Solved by the Invention]

However, in the above-mentioned conventional example, when the rotation speed of the motor increases, a counter electromotive voltage is generated by the motor, and this counter electromotive voltage reduces the voltage applied to the motor, so that a phenomenon occurs in which the current flowing through the motor differs from the intended value. .. For example, where the motor current waveform should be a sine wave, there is a drawback that the peak portion is distorted from the rising edge, which causes a problem that the motor driving sound becomes loud.

【0004】

The present invention is intended to solve the above-mentioned drawbacks, and is intended to provide a stepping motor drive control device in which the rotation of the motor is always smooth.

【0005】

[Means for solving problems]

In order to achieve such an object, the present invention monitors a stepping motor drive control device for driving a multi-phase stepping motor and controls the current of the drive circuit so as to obtain a set value by monitoring the current flowing through the stepping motor. It is something to try.

【0006】

[Example]

Hereinafter, examples of the present invention will be described with reference to the drawings, but first, the first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

【0007】

FIG. 1 shows a stepping motor drive control circuit. In FIG. 1, 1 and 2 are input terminals to which a stepping motor drive signal is input, and 3 and 4 are reference waveform signals and input terminals from a serrated wave generation circuit 5. Comparator comparing the stepping motor drive signals from 1 and 2, 6 and 7 are the drive circuit to which the PWM output from comparators 3 and 4 is input, and the output of this drive circuit 6 excites the A phase of the stepping motor 8. The output of the drive circuit 7 excites the B phase of the stepping motor 8. 9 and 10 are current detection resistors, the current detection resistor 9 excites the A phase of the stepping motor 8 and detects the current returned to the drive circuit 6, and the current detection resistor 10 excites the B phase of the stepping motor 8. The current returned to the drive circuit 6 is detected. 11 and 12 are amplifiers that amplify the terminal voltage of current detection resistors 9 and 10, 13 and 14 are comparators that compare the output signals from amplifiers 11 and 12 with the stepping motor drive signals from input terminals 1 and 2. It is a motor drive power supply that determines the power supply voltage of the drive circuits 6 and 7, and the motor drive power supply 15 is controlled by output signals from the comparators 13 and 14.

【0008】

Next, the operation of the above configuration will be described with reference to FIG.

【0009】

The stepping motor drive signal input from the input terminals 1 and 2 is compared with the reference waveform signal from the sawtooth wave generation circuit 5 by the comparators 3 and 4, and is output as a PWM signal from the comparators 3 and 4. The PWM outputs of the comparators 3 and 4 are input to the drive circuits 6 and 7, and excite the A phase and the B phase of the stepping motor 8 to rotate the stepping motor 8.

【0010】

The current that excites the A and B phases of the stepping motor 8 returns to the drive circuits 6 and 7, and then flows through the current detection resistors 9 and 10. At this time, the voltage generated in the current detection resistors 9 and 10 is amplified by the amplifiers 11 and 12, and the amplified signal and the stepping motor drive signal from the input terminals 1 and 2 are compared by the comparators 13 and 14, and actually It will be checked whether the current flowing in the A phase and B phase of the stepping motor 8 is larger or smaller than the intended current value.

【0011】

When the current flowing through the A phase and B phase of the stepping motor 8 is smaller than the intended current value, the voltage of the motor drive power supply 15 is increased by the output signals from the comparators 13 and 14, and the drive circuits 6 and 7 are used. Increase the power supply voltage. When the current flowing through the A phase and B phase of the stepping motor 8 is larger than the intended current value, the voltage of the motor drive power supply 15 is lowered by the output signals from the comparators 13 and 14, and the drive circuit 6 Lower the power supply voltage of 7.

【0012】

Specifically, in the state 1 of FIG. 2, the waveform B1 which is the output of the amplifiers 11 and 12 compared by the comparators 13 and 14 with respect to the waveform of the stepping motor drive signal A1 input to the input terminals 1 and 2 is Since the output value is partially reduced due to the distortion, the comparators 13 and 14 indicate small, and the motor drive power supply 15 raises the motor power supply voltage to output. The motor power supply voltage rises until the counter electromotive voltage generated by the rotation of the stepping motor 8 is offset, and the stepping motor drive signal A as shown in state 2 in FIG.₂Output waveforms B of widens 11 and 12 with respect to the waveform of₂When is the same, the rise of the motor power supply voltage stops.

【0013】

On the contrary, when the output values of the amplifiers 13 and 14 are large, the comparators 13 and 14 indicate large, and the motor drive power supply 15 lowers the motor power supply voltage to output.

【0014】

Also, as shown in Fig. 3, the sum of the current flowing in the A phase and the current flowing in the B phase in the input signal is always a constant value, that is, I._A+ I_BBy inputting a waveform such that = const, for example, a triangular wave having the same amplitude and the same period, the total output torque always shows a constant value.

【0015】

As described above, according to this first embodiment, it is possible to smooth the rotation by stabilizing the output torque of the stepping motor.

【0016】

Next, a second embodiment of the present invention will be described with reference to FIG. 4 and FIG.

【0017】

FIG. 4 shows a stepping motor drive control circuit, and the same parts as those in FIG. 1 are designated by the same reference numerals, and specific description thereof will be omitted.

【0018】

In FIG. 4, 20 is a controller that controls the stepping motor 8, and 21 is a CPU. The current flowing through the coil of the stepping motor 8 is compared with the set value, and the voltage rise / fall signals are output to the motor drive power supply 15. To do. 22 and 23 are A / D converters that convert the voltage value due to the current flowing through the coil of the stepping motor 8 from analog to digital.

【0019】

Next, the operation of the above configuration will be described with reference to the flowchart of FIG.

【0020】

In step S1, the voltage generated by the current flowing through the coil of the stepping motor 8 flowing through the current detection resistors 9 and 10 is A / D converted and read, and whether or not the current value (voltage value) is the intended current value is stepped. Judge with S2. If the current value is the intended value, proceed to step S8. If the current value is not the intended value, the process proceeds to step S3.

【0021】

In step S3, if the A / D converted current value is flowing more than the intended current value, the process proceeds to step S6, and if the current value is less than the intended current value, the process proceeds to step S4.

【0022】

In step S4, a signal for increasing the motor power supply voltage is output to the motor drive power supply 15, the motor power supply voltage is increased in step S5, the process returns to step S2, and the above steps are repeated.

【0023】

Further, in step S6, the motor power supply voltage is lowered to the motor drive power supply 15 to output a signal, the motor power supply voltage is lowered in step S7, and then the process returns to step S2, and the above steps are repeated.

【0024】

In step S8, the output of the signal for raising or lowering the motor power supply voltage to the motor drive power supply 15 is stopped, and the change in the motor power supply voltage is stopped.

【0025】

[Effect of the invention]

As described in detail above, according to the present invention, in the stepping motor drive control device for driving a multi-phase stepping motor, the current flowing through the stepping motor is monitored and the current of the drive circuit is controlled so as to be a set value. By setting this, the distortion of the motor current due to the countercurrent force of the stepping motor 8 can be reduced, and by inputting a triangular wave with the same amplitude and the same period as the drive signal, the stable output of torque and vibration can be achieved. There is an effect that the noise can be reduced because the smooth rotation can be performed by the reduction.

[Simple explanation of drawings]

[Figure 1]

It is a stepping motor drive control circuit diagram which shows 1st Embodiment of this invention.

[Figure 2]

It is a figure explaining the improvement of the current flowing through the motor in the circuit shown in FIG.

[Fig. 3]

It is a signal waveform diagram of the triangular wave input to the motor shown in FIG.

[Fig. 4]

It is a stepping motor drive control circuit diagram which shows the 2nd Embodiment of this invention.

[Fig. 5]

It is a flowchart of the motor drive control circuit shown in FIG.

[Explanation of symbols]

1 and 2 input terminals 3, 4 comparator 5 Sawtooth wave generation circuit 6, 7 drive circuit 8 Stepping motor 9, 10 current detection resistor 11, 12 amplifier 13, 14 comparator 15 Power supply for driving the motor 20 controller 21 CPU 22, 23 A / D converter