JPH0678594A - Drive circuit of pulse motor - Google Patents

Abstract

PURPOSE:To provide a driving circuit for a pulse motor in which power conservation is expedited. CONSTITUTION:A driving circuit for a pulse motor has a plurality of exciting coils 41 and comprises an applied current controller 5 for controlling exciting currents of the coils 41, a motor current value detector 4 for inputting a signal for operating the controller 5, and a load detector 12 for detecting a load state of the motor. The circuit feeds back a detected result of the detector 12 to the detector 4, controls the current to the coil 41 to a suitable value for a load of the motor, saves supply power and to suppress heat generation of the motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse motor drive circuit, and more particularly to a pulse motor drive circuit in which power consumption is reduced and heat generation of the motor is suppressed.

[0002]

2. Description of the Related Art There is a pulse motor as a drive source capable of speed and positioning without feedback, and this pulse motor is used in various automation devices and labor saving devices.

Further, in recent years, higher precision, higher quality and higher performance of these devices have been promoted, and higher precision is also required for driving and controlling the pulse motor.

A conventional pulse motor drive circuit will be described with reference to FIG.

In FIG. 6, 1 is a DC power supply, 2 is the DC power supply 1
A current chopper circuit having 3 is a motor excitation coil switching circuit, 4 is a motor current value detection circuit having a motor current value detection resistor 9 and an amplifier 10. The current chopper circuit 2 is an applied current control unit 5 and a coil 6. , A capacitor 7, a diode 8 and the like, and a motor exciting coil group 4 through the motor exciting coil switching circuit 3
The current applied to 1 is controlled.

The exciting coil group 41 includes exciting coils 41a,
41b, 41c, 41d and 41e are connected in a ring shape, so-called a pentagonal connection.

The motor exciting coil switching circuit 3
Is a transistor 42 and a flywheel diode 43
And switch parts 3a, 3b, 3c, 3d, 3e which are formed by connecting two parallel-connected switches in series, and any two of these switch parts and the exciting coil 41a,
41b, 41c, 41d and 41e are sequentially connected in a bridge shape, and the switch unit 3
By operating the a, 3b, 3c, 3d, and 3e, the current applied state to the exciting coils 41a, 41b, 41c, 41d, and 41e is sequentially moved along the rotation direction of the motor, so that the rotor (not shown). It enables the step rotation of.

The motor exciting coil switching circuit 3
, The motor drive voltage is applied to the DV point, the control current i1 given by the current chopper circuit 2 increases or decreases the motor drive voltage, and the current i2 passes through the transistor 42 of the motor exciting coil switching circuit 3. Current flowing through the exciting coil group 41, and further, the current i3
Is generated by the electromotive force of the exciting coil group 41, and is a surplus that circulates through the flywheel diode 43 of the motor exciting coil switching circuit 3 with the DV, the capacitor 7, the motor current value detecting resistor 9, and the motor exciting coil switching circuit 3. It is an electric current.

In the above-described conventional pulse motor drive circuit, the amplifier 10 detects the potential generated in the motor current value detecting resistor 9, and the applied current control section 5 is driven based on the detected result. It controls the current i1.

The amplifier 10 detects the electric potential of the motor current value detecting resistor 9 so that the current (i1 + i3) shown in FIG.
) Is detected, the control current i1 supplied to the DV point on the circuit is substantially equal to the current discharged from the DV point. Therefore, the current (i2 +
i3) is detected.

In the conventional pulse motor drive circuit described above, constant current control is performed so that the current (i2 + i3) becomes constant.

[0012]

In the above-mentioned conventional pulse motor drive circuit, since constant current control is performed, a constant current is always supplied to the motor regardless of the size of the load on the motor side. For this reason, when the load is light, it means that more current than necessary is being supplied, power is wasted, and the amount of heat generated is large, so it is necessary to take heat dissipation measures so that the function of the circuit is not damaged by heat. I was trying.

In view of the above situation, the present invention aims to provide a pulse motor drive circuit that promotes power saving.

[0014]

According to the present invention, in a drive circuit of a pulse motor having a plurality of exciting coils, an applied current controller for controlling an exciting current of the exciting coil and an applied current controller are operated. A motor current value detection circuit for inputting a signal for controlling the motor current value and a load detection circuit for detecting the load state of the motor are provided, and the detection result of the load detection circuit is fed back to the motor current value detection circuit. It is a feature.

[0015]

[Operation] The state of the load of the motor is detected and fed back to the motor current value detection circuit to control the supply current to the exciting coil to an appropriate value for the load of the motor to suppress the supply of power and heat generation of the motor. .

[0016]

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

In FIG. 1, those having the same functions as those shown in FIG. 6 are designated by the same reference numerals.

A surplus current value detecting resistor 11 is connected between the ground side of the capacitor 7 and the motor exciting coil switching circuit 3, and a surplus current detecting circuit 12 is connected to the surplus current value detecting resistor 11. The surplus current detection circuit 1
2 detects the load state of the motor, and outputs the output of the surplus current detection circuit 12 to the motor current value detection circuit 4.

The surplus current detection circuit 12 will be described.

An amplifier 1 is attached to the excess current value detecting resistor 11.
3 is connected to the amplifier 13, and a peak hold circuit 17 including a diode 14, a capacitor 15, and a resistor 16 is connected to the amplifier 13.
An amplifier 18 is connected via a resistor 30, and a resistor 30 for adjusting an amplification factor is connected to the amplifier 18 and a resistor 2
A buffer circuit 22 is connected via an integrating circuit 19 composed of 0 and a capacitor 21.

The buffer circuit 22 includes an inverting amplifier 2
3. The amplifier 24 is connected and the output from the amplifier 24 is input to the motor current value detection circuit 4 via the resistor 31. Further, the reference voltage V1 input to the inverting amplifier 23
Is adjustable by the resistor 25.

Thus, the surplus current detection circuit 12 having the above configuration
Is output to the motor current value detection circuit 4.

The amplifier 10 of the motor current value detection circuit 4
Is connected to the motor exciting coil switching circuit 3 side of the excess current value detecting resistor 11 and is compared and amplified with the potential input from the amplifier 24. The potential on the side of the surplus current value detecting resistor 11 is adjusted by the resistors 26 and 27, and the potential from the amplifier 24 is adjusted by the resistors 28 and 29.

The applied current controller 5 controls the current to the motor exciting coil switching circuit 3 based on the signal from the motor current value detecting circuit 4.

A potential based on the current (i1 + i2-i3) flowing in the motor current value detecting resistor 9 and the surplus current value detecting resistor 11 is input to the + terminal of the amplifier 10.
Further, the amplifier 13 outputs a potential generated across the resistor 11 for detecting the excess current value, and the potential is caused by the current (i3 -i2). When the current (i3 -i2)> 0, the amplifier 1
3 outputs a positive voltage corresponding to the increase of i3 with respect to i2.

The peak voltage of the output of the amplifier 13 is held by the peak hold circuit 17, and the output value is smoothed and input to the amplifier 18. The amplifier 1
Reference numeral 8 amplifies the signal from the amplifier 13 and further converts it into a direct current component by an integrating circuit 19.

The signal from the integrator circuit 19 is low-impedance-converted by the buffer circuit 22, inverting-amplified by the inverting amplifier 23, the reference voltage is adjusted by the resistor 25, and the feedback of the increment of i3 is provided by the amplifier 24. Allows the amplifier 10 to operate properly. or,
The amplifier 10 is an error amplifier that controls the applied current control unit 5, and operates so that the + input voltage becomes equal to the −input voltage.

The above-mentioned i2 and i3 have a relation that the ratio of i2 and i3 changes in proportion to the magnitude of the load of the motor during rotation of the motor. That is, when the load on the motor is small, the number of rotations of the motor increases and i2> i3, i2 =
i3, i2 <i3 changes, and if the motor load is large, i2> i3 remains as it is even if the rotation speed of the motor increases. Furthermore, when the motor load is small and i2 <i3, the motor load increases to i2> i3.

Therefore, when the current (i3-i2) is detected by the surplus current detection circuit 12 and is input to the motor current value detection circuit 4, when i2 <i3 (motor load is small), the motor Reduce the drive current, i2> i3
When (motor load is large), increase the motor drive current to the first set value. Further, by appropriately selecting the values of the resistors 30 and 31, it is possible to arbitrarily select the amount of change in the current (i1 + i2-i3) with respect to the change in the current i3.

When the load on the motor is small, the drive current of the motor is reduced to reduce unnecessary current supply to the motor to suppress heat generation of the motor. When the load on the motor is increased, the motor is driven. Increase the current to bring out the maximum torque characteristics of the motor.

Referring to FIG. 2, the current flowing through each layer coil of the 5-phase motor and the current detected by the surplus current value detecting resistor 11 will be described.

Excitation coil a phase, b phase, c phase, d phase, e
The currents flowing in the respective phases have a trapezoidal shape, and the cross hatched portion in the figure corresponds to the current i2 and is an exciting current. Also, the dot-hatched portion corresponds to the surplus current i3, and the unmarked portion is the undetected current circulating in the motor.

Thus, the current (i2 -i3) flowing through the excess current value detecting resistor 11 has a sawtooth shape, and when a load is applied, the current at the cross hatched portion increases and the current at the point hatching portion decreases. To do. In the above embodiment, the peak value of the current in the point hatching portion is detected and fed back to the amplifier 10.

A second embodiment will be described with reference to FIG. 3, those parts which are the same as those shown in FIG. 1 are designated by the same reference numerals.

In this embodiment, instead of detecting the current caused by the excess current value detecting resistor 11, the load state of the motor is detected by the drive voltage of the motor and is fed back to the amplifier 10.

The motor exciting coil switching circuit 3
A drive voltage detection unit 37 of the motor is connected to a power supply line to the motor, and a signal from the drive voltage detection unit 37 is fed back to the applied current control unit 5. The drive voltage detector 37 will be described below.

The motor exciting coil switching circuit 3
A resistor 32 and a resistor 33 are connected in series to a power supply line to the motor to divide the drive voltage of the motor and input the divided voltage value to the amplifier.

A voltage division value adjusting circuit 36 including an amplifier 35 is connected to the input line for the voltage division value. The signal of the amplifier 34 is input to the inverting amplifier 23. The inverting amplifier 23,
The amplifier 24 adjusts the output value of the amplifier 34 so that the signal from the amplifier 34 is properly fed back to the amplifier 10 as in the above-described embodiment.

In this embodiment, the drive voltage of the motor is detected, and when the drive voltage rises, the control current supplied to the motor exciting coil switching circuit 3 is reduced. Therefore, there is an inverse relationship between the motor drive voltage and the control current, and the maximum value of the motor output power is adjusted.

Thus, the maximum electric power can be adjusted, an excessive electric power can be prevented from being supplied to the motor, and the heat generation amount of the motor can be suppressed.

In the second embodiment, the resistor 3
A capacitor 38 connected in parallel with the capacitor 3 relaxes the responsiveness when the change in the motor drive voltage is fed back to the amplifier 10. By providing the capacitor 38, the time constant is input to the amplifier 34. Since the input voltage to the amplifier 34 does not immediately increase even if the motor drive voltage rapidly increases, the amplifier 10 reacts,
The control current i is not reduced. Therefore,
Acceleration torque is sufficiently applied to the motor, and the acceleration characteristic is improved. After that, since the detected voltage to the amplifier 34 rises, the control current decreases and the excess current to the motor is suppressed.

It goes without saying that the capacity of the capacitor 38 can be selected according to the required characteristics. Further, the one that alleviates the responsiveness at the time of feedback is not limited to the capacitor, and an appropriate delay means may be used.

The third embodiment shown in FIG. 4 is a combination of the first embodiment shown in FIG. 1 and the second embodiment shown in FIG.

That is, the value of the current flowing through the excess current value detecting resistor 11 is detected, the motor drive voltage is detected by the drive voltage detector 37 ', and the current value and the drive voltage are combined and fed back to the amplifier 10. Is.

The feedback amount for detecting the excess current is adjusted by the resistor 30, and the feedback amount of the motor drive voltage is adjusted by the resistor 31.

Thus, the third embodiment has the respective characteristics of the first and second embodiments.

Next, FIG. 4 shows a fourth embodiment. The fourth
This embodiment is substantially the same as the above-mentioned first embodiment, but in order to detect the current (i3 -i2), a surplus current value detecting resistor 11 is provided in the power supply line of the motor.

The structure and operation of the fourth embodiment are the same as those of the first embodiment, so the description thereof will be omitted.

Although the above-mentioned embodiments have all described the so-called pentagon-connected pulse motors of five phases, the excitation coils can be implemented as long as the excitation coils are radially connected and a plurality of excitation coils of two or more phases are provided. Needless to say.

[0050]

As described above, according to the present invention, it is possible to supply an appropriate drive current to the drive circuit of the pulse motor according to the state of the load of the motor. Can be suppressed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a current waveform of the example.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 6 is a circuit diagram showing a conventional example.

[Explanation of symbols]

 4 Motor Current Value Detection Circuit 5 Applied Current Control Section 12 Surplus Current Detection Circuit 37 Drive Voltage Detection Section 41 Excitation Coil Group

Claims (5)

[Claims] 1. A pulse motor drive circuit having a plurality of exciting coils, wherein a motor for inputting an applied current controller for controlling an exciting current of the exciting coil and a signal for operating the applied current controller. A pulse motor drive circuit characterized in that a current value detection circuit and a load detection circuit for detecting a load state of the motor are provided, and a detection result of the load detection circuit is fed back to the motor current value detection circuit. . 2. The pulse motor drive circuit according to claim 1, wherein the load detection circuit detects a difference between the exciting current and the surplus current. 3. The pulse motor drive circuit according to claim 1, wherein the load detection circuit detects the drive voltage of the motor. 4. The pulse motor drive circuit according to claim 1, wherein the load detection circuit detects a difference between the exciting current and the surplus current and a drive voltage of the motor. 5. The drive circuit for a pulse motor according to claim 1, further comprising delay means for reducing feedback responsiveness.