JPH03270693A - Driving circuit for step-motor - Google Patents

Abstract

PURPOSE:To eliminate electromagnetic influence due to fluctuation of ripple in a winding current and electric influence due to fluctuation of winding terminal voltage onto the environment by providing at least two sets of lowpass filters in series with a step-motor. CONSTITUTION:When an input control signal S3 to a predriver 24 is H, a transistor 3 is turned ON whereas transistors 1, 4 are turned OFF because control signals S1, S2 are L. When a control signal So is H, a transistor 2 is turned ON and a current flows from a power supply terminal 12 through the transistor 3, a winding 14, smoothing circuits 30, 29, the transistor 2 and a current detecting resistor 11. When the control signal So is L, the transistor 2 is turned OFF and a current flows through the current detecting resistor 11, a diode 8, the winding 14, the smoothing circuits 30, 29, a diode 5 and the power supply terminal 12. When the current flow is reversed, a transistor 1 is turned ON and a transistor 4 is turned ON or OFF.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a stepping motor drive circuit, and more particularly to a stepping motor drive circuit provided with a filter circuit for reducing electromagnetic noise generated from the stepping motor. be.

[Conventional technology]

Conventionally, this type of stepping motor drive circuit has a third
As shown in the figure, there are four switching elements, t, b transistors 1, 2, 3.4, and diode 5, 6, 7.8.
, a pre-driver 9, 10, and an i-flow ejection resistor 11, a power supply terminal 12 is connected to a power supply, and a control signal S is input to an input terminal 100 case or an input terminal 101. Among them, 13 is a stepping motor, and 14 is a winding of the stepping motor 13.

FIG. 4 is a timing diagram showing the operation of the circuit of FIG. 3. In Fig. 4, (,) indicates an input signal S of a binary logic level input to the driver 9. When this input signal S is at a low level, transistors 2 and 3 are turned off. So, high level Toki, transistor 2
As a result, transistor 3 is turned on. Figure (b),
(c) is a stepping motor with 130 turns! l! 14 points PI, Ps voltage v1. The figure (d) shows the motor voltage V, and the voltage Ili [14
It shows the electric current flowing through.

In FIG. 3, the current detecting resistor 11 is connected to a circuit (not shown) through which a current of the same magnitude as that of the winding current flows, and a voltage drop across the current detecting resistor 11 is detected. The ratio of the high level width to the low level width of the control signal SO was set at 12 so that the size of the control signal SO was linear at one point. In other words, if you want to increase the winding current I, make it wider than the control signal SO high level width and low level width, and conversely, the winding current ! When it is desired to reduce the storage capacity, the low level width of the control signal S is made wider than the high level width. Among them, according to the operating waveform in Fig. 4,
It is assumed that the control signal S is at a low level.

[Problem to be solved by the invention]

The conventional stepping motor drive circuit described above uses winding current! The generated magnetic field changes due to ripples, which has an adverse electromagnetic effect on the surrounding environment where the stepping motor drive circuit is installed.

Also, stepping motor OqI! There is also a problem in that a change in the terminal voltage of I causes an adverse electric field effect on the surrounding environment.

[Means to solve the problem]

In order to solve these problems, a stepping motor drive circuit according to the present invention includes at least two sets of rotor cross filters connected in series with the windings of the stepping motor.

[Effect]

According to the present invention, by connecting two sets of low-pass filters, fluctuations in the voltage applied to the windings of the stepping motor are reduced.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing the structure of an embodiment of a stepping motor drive circuit according to the present invention, and the same parts as in the previous figures are given the same reference numerals.

In the figure, pre-drivers 100, 101, 102, and 103 control the on/off of transistors 1, 2, and 3.4, respectively, and 21, 22, 23, and 24 are binary logic level control signals S@+Sl+8! +Sj input terminal, 2
5.26 is an inductor, 27.28 is a capacitor, the inductor 25 and capacitor 27 constitute a first low-pass filter 29, and the inductor 26 and capacitor 2
B constitutes a second ronox filter 30.

FIG. 2 is a timing chart showing the operation of the circuit in FIG. (C) shows the motor voltage V applied to point P1 in FIG.
) indicates the motor voltage v3 at point P in FIG. It shows.

Next, the operation shown in FIG. 1 will be explained using FIG. 2.

In FIG. 1, the control signal S3 input to the predriver 24 is fixed at a high level, so the transistor 3 is turned on. Although not shown, the control signal 5sjr and the control signal S2 are fixed at a low level, so the transistors 1 and 4 are turned off. When the control signal Sod is at a high level, transistor 2 is turned on, and transistors 3 . Inductor 269 winding 14. Inductor 25. Transistor 2. A current flows through the current detection resistor 11.

Meanwhile, when the control signal SO is at a low level, the transistor 2 is turned on and the current detection resistor 11. Diode 81 Inductor 261 Winding 14. Inductor 25° diode 5.
A current flows through the power supply terminal 12. At this time, the first low-pass filter 29 made up of an inductor 25 and a capacitor 2T, and the second low-pass filter 30 made up of an inductor 26 and a capacitor 28, the motor voltage v!
and the winding current is smoothed. ! The winding current! When flowing in the opposite direction, transistor 1 is turned on and transistor 4 is turned on or off. In order to set the winding current to a desired value, the current flowing through the current detection resistor 11 is detected and controlled by a current detection circuit, although it is not shown in the figure, in the same way as in a conventional stepping motor drive circuit. Signal S
This can be achieved by changing the ratio between the high level width and the low level width. The inductances of the inductors 25 and 26, the capacitor 27.
The frequency of the signal input to each of the 28 capacitors and the control signal S0 is set.

〔Effect of the invention〕

As explained above, according to the present invention, since at least two sets of low-pass filters are connected in series with the windings of the stepping motor, fluctuations in the voltage applied to the windings of the stepping motor are reduced. This provides an extremely excellent effect of reducing electromagnetic and electric field effects on the environment.

[Brief explanation of drawings]

Figure WJ1 shows an embodiment of the stepping motor drive circuit according to the present invention! s, the circuit diagram shown in Fig. 2 is the first
Figure 3 is a timing chart explaining the operation of the figure; Figure 3 is a circuit diagram showing the configuration of a conventional stepping motor drive circuit;
FIG. 4 is a timing chart explaining the third operation. 1.2,3,4...transistor, 5,6°7.8
...Diode, 11...Current detection resistor, 12
...Power terminal, 13...Stepping motor,
14...Winding, 21.22. 23.24-...Predriver, 25,266...
Inductor, 27.28... Capacitor, 29...
...first low-pass filter, 30...second low-pass filter.

Claims (1)

[Claims] In a stepping motor drive circuit in which the magnitude of the current flowing through the stepping motor winding can be arbitrarily set by adjusting the on and off periods of a switching element, A stepping motor drive circuit, characterized in that at least two low-pass filters are connected.