JPH0733598Y2 - Stepping motor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a stepping motor device having a chopper-type constant current circuit.

[Prior Art] In order to make the current flowing through the winding of a stepping motor constant, a winding current that changes in a triangular wave or a sawtooth waveform is detected, and the detected voltage corresponding to this is compared with a reference voltage by a comparator. , It is possible to obtain a signal indicating the time when the detected voltage reaches the reference voltage, form a control pulse based on this signal, and use this control pulse to ON / OFF control the switching element for exciting period determination or the switching element for current control. Already done.

[Problems to be Solved by the Invention] By the way, the chopping control pulses of the first phase (A phase) and the second phase (B phase) are formed independently and are not synchronized. If there is a frequency shift or duty shift of the chopping control pulses of the first phase and the second phase due to the non-synchronization, a low frequency beat (motor abnormal noise) is generated based on this.
Occurs.

Also, if the level of ringing noise generated when switching the winding current is high, accurate current detection becomes impossible,
Accurate current control becomes impossible.

Therefore, an object of the present invention is to provide a stepping motor device that can prevent malfunction due to noise. Another object of the present invention is to provide a stepping motor device that can prevent malfunction due to noise and can drive the first winding and the second winding in synchronization.

[Means for Solving the Problems] The invention according to claim 1 for achieving the above object is a first and second device connected between one end and the other end of a DC power supply, respectively.
Windings, first and second switching elements respectively connected in series to the first and second windings, and the first
And an excitation signal generation circuit that generates first and second excitation signals indicating an excitation period of the second winding so as to have a temporally overlapping period, and flows through the first and second windings. First and second current detectors for respectively detecting a current, a reference voltage circuit having first and second reference voltage terminals, and one input terminal connected to the first reference voltage terminal. A first reference voltage provided from the first reference voltage terminal and a first reference voltage provided from the first current detector, the first reference voltage provided from the first reference voltage terminal and the other input terminal connected to the first current detector. Based on the output of the first comparator, which outputs a signal indicating the time point when the current flowing through the first winding reaches the first reference voltage by comparing with the detection voltage of 1; To turn on / off the first switching element. A first control pulse generating circuit for generating a first control pulse for generating the first control pulse in a cycle shorter than the first excitation signal, and the first control pulse obtained from the first control pulse generating circuit. It has a first gate circuit for giving the first switching element a period determined by the first excitation signal, and one input terminal connected to the second reference voltage terminal, and the second gate circuit A second reference voltage applied from the second reference voltage terminal and a second detection voltage applied from the second current detector are provided, which has the other input terminal connected to the current detector. Compared to,
A second comparator that outputs a signal indicating when the current flowing through the second winding reaches the second reference voltage;
A second control pulse generation circuit for generating a second control pulse for ON / OFF control of the second switching element based on the output of the second comparator in a cycle shorter than that of the second excitation signal. A second gate circuit that applies the second control pulse obtained from the second control pulse generating circuit to the second switching element during a period determined by the second excitation signal; A first capacitor connected between one input terminal and the other input terminal of the first comparator; and a second capacitor connected between one input terminal and the other input terminal of the second comparator And a third capacitor connected between the input terminals of one of the first and second comparators, respectively.

According to a second aspect of the present invention, in a stepping motor device provided with a switching element for exclusive use in current control without using the switching element for determining the excitation period also as current control.
Similarly to the above, the first, second and third capacitors are provided.

The first and second reference voltage terminals are the same as those of the first embodiment.
And the second reference voltage lines 12 and 13, and the first and second control pulse generation circuits are the capacitors 33 of the embodiment.
And a resistor 34, and a reference voltage source 32
And a comparator 27, respectively.

[Operation] In any of claims 1 and 2, the first and second capacitors have an operation of changing the reference voltage when the current of the winding is switched. As a result, it is possible to prevent noise generated when switching the winding current from crossing the reference voltage.

Also, the third capacitor has a function of correlating the first and second reference voltages with each other. This enables the synchronous operation of the first and second comparators.

[First Embodiment] Next, a stepping motor device according to a first embodiment of the present invention will be described with reference to FIGS.

First, second, third and fourth windings having substantially the same impedance between one end and the other end of the DC power supply 1.
2a, 2b, 2c and 2d are respectively connected. First to fourth switching elements for exciting period determination and constant current control
3a, 3b, 3c, and 3d are insulated gate FETs, and are connected in series to the first to fourth windings 2a to 2d, respectively. First
And a resistor 4a as a first current detector is connected between the common connection point of the third switching elements 3a and 3c and the ground, and a diode 5a for forming a winding energy emission path is connected in parallel to this. There is. Similarly, the second connection is provided between the common connection point of the second and fourth switching elements 3b and 3d and the ground.
A resistor 4b serving as a current detector is connected to a winding energy emission path forming diode 5b in parallel.

The first and second control circuits 6a and 6b are the excitation signal generation circuit 7
In response to the excitation signals of the output lines 7a and 7b of the above, the first to fourth switching elements 3a to 3d are ON-controlled by a predetermined excitation method (for example, a two-phase excitation method), and the current detection resistors 4a and 4b.
It is configured to perform intermittent control (chopping control) in response to a current detection signal obtained from the detection lines 8 and 9 connected to. The output lines of the control circuits 6a and 6b are connected to the gates of the switching elements 3a to 3d.

Reference numeral 10 is a reference voltage circuit, which is composed of voltage dividing resistors R1 and R2 connected between the power supply terminal 11 and the ground, and resistors R3 and R4 connected to the voltage dividing points, respectively. One end of the resistor R3 is a first reference voltage terminal and is connected to the first reference voltage line 12 through the first reference voltage line 12.
Connected to the control circuit 6a. One end of the resistor R4 is a second reference voltage terminal, and is connected to the second control circuit 6b via the second reference voltage line 13.

The first, second and third capacitors C1, C2 and C3 are related to the present invention, and the first capacitor C1 is connected between the first current detection line 8 and the first reference voltage line 12. The second capacitor C2 is connected between the second current detection line 9 and the second reference voltage line 13, and the third capacitor C3 is connected between the first and second reference voltage lines 12 and 13. Is connected in between.

2 and 3 show the rotor and the stator of the stepping motor. A rotor 22 including a permanent magnet 21 is fixed to a shaft 23. The stator 24 includes the magnetic poles 25a and 25b of the stator core 25.
It is configured by winding windings 2a to 2d around.
The first and third windings 2a and 2c are wound around the magnetic pole 25a, and the magnetic pole 2
Second and fourth windings 2b and 2d are wound around 5b. Since the structure of the rotor 22 and the stator 24 of this stepping motor is the same as that of the well-known bifilar winding four-phase stepping motor, detailed description thereof will be omitted.

FIG. 4 shows the control circuit 6a of FIG. 1 in detail. The control circuit 6a includes a current detecting comparator 26a, a square wave forming comparator 27, and first and second NOT circuits 28 and 29.
, The first and second AND gates 30 and 31, and the reference voltage source 32
And a capacitor 33 and a resistor 34 for obtaining a triangular wave.

One input terminal of the current detection comparator 26a is connected to the first reference voltage line 12, and the other input terminal is connected to the current detection line 8. One input terminal of the square wave forming comparator 27 is connected to the output terminal of the current detecting comparator 26a, and the other input terminal is connected to the reference voltage source 32. One input terminal of the first AND gate 30 is connected to the excitation signal generation circuit 7 via the NOT circuit 29,
The other input terminal is connected to the comparator 27 via the NOT circuit 28, and the output terminal is connected to the gate of the third switching element 3c. One input terminal of the second AND gate 31 is connected to the excitation signal generation circuit 7, the other input terminal is connected to the comparator 27 via the NOT circuit 28, and the output terminal is connected to the gate of the first switching element 3a. It is connected. The second control circuit 6b in FIG. 1 is not shown in detail, but is constructed substantially the same as the first control circuit 6a. One input terminal of the second comparator 26b at the input stage in the second control circuit 6b is connected to the second reference voltage line 13, and the other input terminal is connected to the current detection line 9.

FIG. 5 shows in principle the waveform of each part when the stepping motor of FIG. 1 is driven by the two-phase excitation method. That is, the fifth
Figures (A) and (B) are excitation signals, and are shown in Figures 5 (C) and (D).
(E) and (F) are gate signals of the first to fourth switching elements 3a to 3d. Now, taking the first switching element 3a as an example, the on-time width T of the excitation signal shown in FIG.
Is not turned on for the entire period of, and is turned on intermittently at a cycle shorter than the excitation signal as shown in FIG. 5 (C).

The circuit operation of FIG. 4 will be described with reference to FIG. 6 showing the state of each part during the period in which the third switching element 3c is on-controlled. FIG. 6 (A) shows the voltage across the current detection resistor 4a.
The relationship between Vr1 and the reference voltage V1 is shown before the capacitors C1 to C3 are connected. A positive voltage corresponding to the current during the ON period of the third switching element 3c is applied across the resistor 4a,
The voltage corresponding to the forward voltage drop of the diode 5a during the off period of the switching element 3c is obtained. The current detection voltage Vr1 is compared with the reference voltage V1 in the current detection comparator 26a, and when the detection voltage Vr1 reaches the reference voltage V1 at the time t1, the output of the comparator 26a becomes low level and the capacitor 33
Is discharged. Therefore, the input voltage Va of the pulse forming comparator 27 decreases as shown in FIG. 6 (B),
The output voltage Vb of the comparator 27 becomes high level as shown in FIG. 6 (C), the output of the NOT circuit 28 and the AND gate.
The output of 30 becomes low level as shown in FIG. 6 (D).
The third switching element 3c that was in the ON state before t1
When it is turned off at t1, the detection voltage Vr1 drops, so the output of the current detection comparator 26a becomes high level again,
Charging of the saw (triangle wave) generation capacitor 33 starts again. The charging voltage of the capacitor 33 is the voltage V2 of the reference voltage source 32.
When it reaches (about 2V), the output of the pulse forming comparator 27 is inverted to the low level. As a result, NOT circuit 28 and A
The output of the ND gate 30 becomes high level, and the third switching element 3c is turned on again at time t2. Even if the output of the comparator 27 is inverted at t2, the capacitor 33 is charged by the resistor 34
Continue through and are discharged at t3. In this embodiment, the off period (t1 to t2) of the third switching element 3c is kept constant and the on period (t2 to t3) is variably controlled. Third
During the ON period of the switching element 3c, the power supply 1,
The current 11 shown in FIG. 6 (E) flows through the circuit composed of the winding 2c, the switching element 3c, the current detection resistor 4a, and the ground, and t1
During the off period from t3 to t3, the energy stored based on the excitation of the winding 2c is released through the winding 2a electromagnetically coupled thereto. That is, winding 2a, power supply 1, bypass diode 5a, switching element 3a built-in diode (FET
Current I2 flows in a closed circuit consisting of a built-in diode. The direction of this current is actually the direction indicated by the arrow 35, but since it is defined as the direction indicated by I2 in FIG. 4, it has the waveform shown in FIG. 6 (F). The combined current indicated by I in FIG. 4 has a waveform shown in FIG. 6 (G). The operation during the period in which a signal for exciting the third winding 2c is generated from the excitation signal generating circuit 7 has been described with reference to FIG. The operation during the excitation period is also substantially the same.

Next, the synchronization between the excitation of the first and third windings 2a and 2c and the excitation of the second and fourth windings 2b and 2d will be described with reference to FIG. When the currents of the windings 2a to 2d are controlled to be turned on and off by the switching elements 3a to 3d, the currents of the windings 2a to 2d, that is, the detection voltages Vr1 and Vr2 of the current detection lines 8 and 9 are shown in FIG.
It changes as shown by a broken line in (B). When the detection voltages Vr1, Vr2 change abruptly at times t1, t2, t3, t4, etc., the reference voltage V1 of the first and second reference voltage lines 12, 13 is passed through the first and second capacitors C1, C2. , V11 also changes like a differential pulse. Ringing noise occurs when the current of the windings 2a to 2d is switched, but since the reference voltages V1 and V11 change when the current is switched, the noise does not cross the reference voltage and malfunction does not occur.

Since the windings 2a to 2d each have an inductance, the winding current has a ramp and increases, and reaches the first reference voltage V1 at t2, t4 and the like. As a result, the output of the first comparator 26a is inverted, the capacitor 33 shown in FIG. 4 is discharged, the current in the winding 2a or 2c is cut off, and the energy in the winding 2a or 2c is released. When the detection voltage Vr1 obtained based on the current detection resistor 4a suddenly decreases, the first capacitor C
The reference voltage V1 of the first reference voltage line 12 coupled via 1 also changes into a differential wave shape. As shown in FIG. 7 (A), when the potential of the first reference voltage line 12 decreases, the second reference voltage V11 of the second reference voltage line 13 coupled by the third capacitor C1 also changes to the seventh reference voltage V11. It decreases as shown in FIG. As a result, even if the rise of the second detection voltage Vr2 obtained based on the second current detection resistor 4b is slightly delayed, the second reference voltage V11 will be crossed at an early opportunity, and the second or The current in the fourth winding 2b or 2d is cut off. Therefore, the first or third winding 2a, 2c and the second or fourth winding 2b, 2d are turned off substantially at the same time.

In such a synchronous operation, when the second detection voltage Vr2 shown in FIG. 7 (B) crosses the second reference voltage V11, the first detection voltage Vr1 shown in FIG. 7 (A) becomes the first detection voltage Vr1. The same occurs in the case before the time when the reference voltage V1 is crossed.

Current of first or third winding 2a, 2c and second or fourth winding
If the currents 2b and 2d are synchronized at the time of driving by the two-phase excitation method, generation of low-frequency beat due to frequency shift or duty shift is suppressed.

This embodiment has the following effects.

(1) It is possible to prevent malfunction due to noise based on changes in the reference voltages V1 and V11 due to the provision of the first and second capacitors C1 and C2.

(2) The third capacitor C3 makes it possible to change the first and second reference voltages at the same time and drive them synchronously. That is, despite the self-excited chopping control, a plurality of phases can be driven synchronously and an abnormal sound can be suppressed.

(3) In the present embodiment, it is not necessary to provide a backflow prevention diode in series with the first to fourth switching elements 3a to 3d composed of FETs.

[Second Embodiment] Next, a stepping motor device according to a second embodiment of the present invention shown in FIG. 8 will be described. However, in FIG. 8, the substantially same parts as those in FIGS. 1 to 4 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 8, the DC power supply 1 and the first and third windings 2
The first current control switching element S1 is connected between a and 2c, and the DC power supply 1 and the second and fourth windings 2b and 2d
A second current control switching element S2 is connected between the first and second control terminals. The first and second current control switching elements S1 and S2 are for making the current flowing through the windings 2a to 2d constant, and are composed of FETs or bipolar transistors, and have a cycle shorter than the cycle of the excitation signal. ON / OFF controlled. First to fourth switching elements 3a to 3 composed of FETs
A switching element for exciting period determination is connected to the exciting signal generating circuit 16a. Excitation signal generation circuit 16a
Applies the excitation signal of FIG. 5 (A) to the first switching element 3a, and the signal of which the phase of the excitation signal of FIG. 5 (A) is inverted to the third switching element 3c. The excitation signal of FIG. 5 (B) is applied to 3b, and the inverted signal of FIG. 5 (B) is applied to the fourth switching element 3d.

The first and second chopper control circuits 36a and 36b include first and second current detecting comparators 26a and 26b. Now, the first chopper control circuit 36a and the first control circuit 6a shown in FIG.
Comparing with the above, the first chopper control circuit 36a corresponds to the circuit portion including the comparators 26a and 27, the NOT circuit 28, the reference power source 32, the capacitor 33, and the resistor 34 in FIG. The second chopper control circuit 36b is also configured similarly to the first chopper control circuit 36a.

The connection of the reference voltage circuit 10, the detection lines 17, 18 and the first to third capacitors C1 to C3 to the first and second current detecting comparators 26a and 26b is the same as that shown in FIG. The ON / OFF control pulses of the second current control switching elements S1 and S2 are formed in the same manner as in FIG. 4, and the synchronous drive becomes possible.

[Modification] The present invention is not limited to the above-described embodiments, and the following modifications are possible, for example.

(1) The present invention can be applied not only to the two-phase excitation method but also to the 1-2-phase excitation method.

(2) The windings 2a to 2d may be unifilar windings.

(3) FE as the first to fourth switching elements 3a to 3d
If T does not have a diode in antiparallel, then FET
Alternatively, a diode may be externally connected in anti-parallel.

(4) The first to fourth switching elements 3a to 3d can be replaced with other switching elements such as bipolar transistors.

[Advantage of Invention] As described above, according to the inventions of claims 1 and 2, it is possible to prevent an operation caused by noise.

Further, it becomes possible to flow current in synchronization with the winding of one phase and the winding of the other phase. Thereby, the abnormal sound of the stepping motor can be suppressed.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a stepping motor device according to the first embodiment of the present invention, and FIG. 2 is a sectional view of a portion corresponding to the line II-II in FIG. 3 showing a stator and a rotor of the stepping motor. 3, FIG. 3 is a sectional view of a portion corresponding to line III-III in FIG. 2, FIG. 4 is a circuit diagram showing the control circuit of FIG. 1 in detail, and FIG. 5 is a voltage waveform diagram of each portion of FIG. FIG. 6 is a waveform diagram of each part of FIG. 4 in a state in which the first to third capacitors of FIG. 4 are omitted, FIG. 7 is a waveform diagram showing a change of the reference voltage, and FIG. It is a circuit diagram which shows the stepping motor apparatus of an Example. 1 ... Power supply, 2a, 2b, 2c, 2d ... Winding, 3a, 3b, 3c, 3d ... Switching element, 4a, 4b ... Current detection resistor, 6a, 6b ... Control circuit, 7
... excitation signal generation circuit, 10 ... reference voltage circuit, C1, C2, C3 ... first, second and third capacitors, S1, S2 ... current control switching element.

Claims (2)

[Scope of utility model registration request] 1. A first and second winding connected to one end and the other end of a DC power supply, respectively, and first and second windings connected in series to the first and second windings, respectively. 2 switching elements, and 1st and 2nd indicating excitation periods of the 1st and 2nd windings
Excitation signal generating circuit for generating the excitation signals of the first and second current detectors, the first and second current detectors detecting the currents flowing through the first and second windings, respectively. A reference voltage circuit having first and second reference voltage terminals, and another input having one input terminal connected to the first reference voltage terminal and connected to the first current detector A first reference voltage provided from the first reference voltage terminal and a first detection voltage provided from the first current detector, and comparing the first detection voltage with a terminal; A first comparator that outputs a signal indicating a time point when the current flowing through the first reference voltage has reached the first reference voltage; and an on / off control for controlling the first switching element based on the output of the first comparator. The first control pulse is the first A first control pulse generating circuit which is generated in a cycle shorter than the excitation signal of, and the first control pulse obtained from the first control pulse generating circuit in a period determined by the first excitation signal. A first gate circuit for supplying the first switching element and one input terminal connected to the second reference voltage terminal, and the other input terminal connected to the second current detector. A current flowing through the second winding by comparing a second reference voltage provided from the second reference voltage terminal with a second detection voltage provided from the second current detector. A second comparator that outputs a signal indicating a time point when the voltage reaches the second reference voltage, and a second comparator for ON / OFF controlling the second switching element based on the output of the second comparator. A control pulse is applied to the second excitation A second control pulse generating circuit which is generated in a cycle shorter than a signal, and the second control pulse which is obtained from the second control pulse generating circuit during the period determined by the second excitation signal. A second gate circuit that supplies the second switching element, a first capacitor connected between one input terminal and the other input terminal of the first comparator, and one input of the second comparator Stepping motor device including a second capacitor connected between a terminal and the other input terminal, and a third capacitor connected between one input terminals of the first and second comparators . 2. A first and second winding connected respectively between one end and the other end of a DC power supply, and first and second windings respectively connected in series to the first and second windings. 2 switching elements for exciting period determination, and 1st and 2nd showing exciting periods of the 1st and 2nd windings.
Generate the excitation signal of with the time overlapping period,
An excitation signal generation circuit that supplies the first and second excitation signals to the first and second excitation period determining switching elements, respectively, and an excitation signal generation circuit that is connected in series to the first and second windings, respectively. First and second current control switching elements, first and second current detectors for detecting currents flowing through the first and second windings, respectively, and first and second references A reference voltage circuit having a voltage terminal, one input terminal connected to the first reference voltage terminal, and the other input terminal connected to the first current detector; Comparing the first reference voltage applied from the reference voltage terminal of the first reference voltage and the first detection voltage applied from the first current detector to determine that the current flowing through the first winding is the first reference voltage. The first coil that outputs a signal indicating when the voltage is reached A first control pulse for turning on / off the first current control switching element based on the output of the comparator and the first comparator, the first control pulse being generated in a cycle shorter than that of the first excitation signal. 1 control pulse generating circuit, and one input terminal connected to the second reference voltage terminal, and the other input terminal connected to the second current detector, the second The second reference voltage applied from the reference voltage terminal is compared with the second detection voltage applied from the second current detector, and the current flowing through the second winding is the second reference voltage. A second comparator that outputs a signal indicating a time point at which the second current control switching element is turned on and off based on the output of the second comparator. First excitation A second control pulse generating circuit which is generated in a cycle shorter than a signal, a first capacitor connected between one input terminal and the other input terminal of the first comparator, and the second comparator A second capacitor connected between the one input terminal and the other input terminal, and a third capacitor connected between the one input terminals of the first and second comparators. Stepping motor device.