JPH0426397A - Driving apparatus for stepping motor - Google Patents

Abstract

PURPOSE:To improve an energy utilization efficiency and improve responsiveness against phase switching by a distributing circuit by a method wherein a single- directional device is connected in a forward direction to a power supply line for an exciting coil. CONSTITUTION:In order to block a current which is made to flow from the collector side to the emitter side of a chopping transistor 2 by electromotive forces which are induced in exciting coils except the selected one when a phase is switched, a single-directional device are connected in a forward direction to a power supply line for the exciting coil. That is, a diode 6 is connected in a forward direction between the emitter of the transistor 2 and the power supply 4. Further, a capacitor 7 is connected to the anode side of the diode 6. With this constitution, an energy utilization factor can be improved and the responsiveness at the switching of the coil can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a stepper motor drive device, and more particularly, to a stepper motor drive device that can improve the rise of current supply during phase switching and improve responsiveness. Regarding.

(Prior Art) An example of a main circuit of a conventional stepper motor drive device is shown in FIG.

In the figure, coils A and C1 and B and D, which are magnetically coupled to each other, are stator windings of a stepper motor, and are preferably wound around an iron core (not shown). The current supplied from the power supply 4 is passed through the PNP transistor (
After being chopped (on/off) by the transistor 2 (hereinafter simply referred to as a transistor), it is supplied to the coils AD. That is, the current supplied to the coils A to D is a pulse current whose duty ratio is determined by a control signal applied from the switching control circuit 3 to the base of the transistor 2.

Coils A to D are selected in a predetermined order by the distribution circuit 1, and the pulsed current is supplied to the selected coils to excite them. The coils A, B, C.

When D is selected and excited, the magnetic poles of the rotor 5 are attracted and rotated by the interaction of the magnetic fields generated by the excited coils. The rotational speed of the stepper motor is determined according to the number of pulses of the switching signal outputted to the distribution circuit 1 per unit time.

(Problem to be Solved by the Invention) In the stepper motor drive device described above, for example, the distribution circuit 1
When coil A is selected, an electromotive force is generated in coil C at that moment due to mutual induction between the coils.

Due to the electromotive force, the voltage of the common power supply line rises instantaneously, and the rise of the current supply to the coil A becomes smooth. Similarly, when coil C is energized, an electromotive force is generated in coil A. The same phenomenon occurs between coils B and 0 that are magnetically coupled to each other.

However, in the driving device that uses the chopping control circuit 3 and the transistor 2 to reduce power consumption, when the voltage to be applied to the coil A increases due to the generation of the electromotive force, the voltage is increased from the emitter side of the transistor 2 to the collector side. The potential on the side increases. As a result, a phenomenon occurs in which current flows from the collector side to the emitter side, and there is a problem that the voltage increased due to mutual induction is not used to improve the rise of the current supply to the coil A.

On the other hand, in order to reduce the power consumption of the stepper motor and suppress the heat generation of the excitation coil, There is a technical background that the noping control circuit and transistor are absolutely necessary components.

An object of the present invention is to solve the above-mentioned problems and to effectively utilize the electromotive force generated in other coils due to mutual induction to sharply increase the excitation current of a selected coil. An object of the present invention is to provide a stepper motor drive device that can improve usage efficiency and increase responsiveness when switching coils.

(Means and effects for solving the problem) In order to solve the above-mentioned problems and achieve the object, the present invention uses an electromotive force generated in other excitation coils other than the selected one at the time of phase switching. The feature is that a unidirectional element is connected in the forward direction to the power supply line to the excitation coil in order to prevent current from flowing from the collector side to the emitter side of the chopping transistor.

In the present invention having the above-described configuration, the electromotive force generated in the excitation coil can be effectively used for excitation of the coil, so that the start-up at the time of phase switching can be improved.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are circuit diagrams showing embodiments of the present invention,
The same reference numerals as in FIG. 3 indicate the same or equivalent parts.

In FIG. 1, a diode 6 is arranged between the emitter of the transistor 2 and the power supply 4, connected in the forward direction.
On the other hand, in the example shown in FIG. 2, a diode 6 is arranged and connected in the forward direction between the collector of the transistor 2 and the exciting coils AD. In these embodiments, current flowing from coils A to D to transistor 2 can be blocked.

Note that a capacitor 7 is connected to the at side of the diode 6 in FIG. 1, and to the emitter side of the transistor 2 in FIG. Thereby, when power is instantaneously consumed in the coils A to D due to startup of the stepper motor or load fluctuation, it is possible to supplementally supply current from the capacitor 7.

In this way, in this embodiment, between the emitter of the transistor 2 and the power supply 4, or between the collector and the coil A-D,
That is, a diode 6 is connected in the forward direction to the power supply line for the coils A-D to block current flowing from the coils A-D to the power supply side via the transistor 2. Therefore, when switching between coils A and D, the electromotive force generated in a coil other than the coil selected by the distribution circuit 1 can be effectively used to raise the excitation current of the selected coil.

(Effects of the Invention) As is clear from the above description, according to the present invention, the electromotive force generated at the time of phase switching can be effectively used to start up the excitation current of the coil, so the energy use efficiency is improved and the distribution The response to phase switching by the circuit becomes faster.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams showing one embodiment of the present invention, and Figure 3 is a circuit diagram showing an embodiment of the present invention.
The figure is a circuit diagram showing an example of the prior art. DESCRIPTION OF SYMBOLS 1... Distribution circuit, 2... Transistor, 3... Chopping control circuit, 4... Power supply, 5... Rotor,
6...Diode, 7...Capacitor

Claims (2)

[Claims] (1) A chopping control circuit that outputs a signal for chopping the current supplied from a power source to a PNP transistor, a plurality of excitation coils connected in series to the PNP transistor, and a chopping control circuit that outputs a signal for chopping the current supplied from a power source to the excitation coil. 1. A stepper motor drive circuit having a distribution circuit for supplying in a predetermined order, wherein a unidirectional element is connected in a forward direction to a power supply line for the excitation coil. (2) The stepper motor drive device according to claim 1, wherein the excitation coil is wound around an iron core.