JPS60237897A - Damping circuit of stepping motor - Google Patents

Abstract

PURPOSE:To improve the stability of an operation by inserting a damping resistor after the prescribed time is elapsed from the rise of a pulse, thereby improving the responsiveness of a stepping motor and eliminating a vibration. CONSTITUTION:Switching elements Qa, Qb are conducted during a time t2 after a time t1 from the rise of a motor drive pulse. Thus, an abruptness can be maintained without damping at the rising time, damping resistors Ra, Rb are inserted after rising to attenuate the vibrating current, with the result that the responsiveness of a stepping motor can be improved and a vibration is eliminated to improve the stability of the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a damping circuit for a bipolar drive type step motor.

[Background technology] In order to suppress the blindness and improve the response characteristics, a Gumping resistor is connected in series with the transistor protection guide as shown in Figure 3. There are many cases where this is done.

In the same figure, I is a stator coil, and a diode D
is to circulate the energy stored in the filter I- after turning off the transistor Tr; thus, it is to protect the transistor T, or to attenuate this circulating current as quickly as possible. This method is inserted in series with a resistor R or diode I).This method has the advantage that the circuit configuration is extremely simple compared to the PWL method, but because the polarity is limited, it is only used for unipolar drive types. Therefore, there was a problem that it could not be applied to a bipolar drive type step motor as shown in Fig. 2. Fig. 2 shows the drive circuit of a two-phase excitation bipolar drive type step motor, and (a) In the figure, by switching the current of each filter La and Lb using four switching elements (transistors) at the timing shown in figure (b), the coils of each phase can be changed as shown in figure (c). As shown in , it is excited by a two-phase, two-pole current.This drive system has the advantage of increasing torque and approximately twice the efficiency compared to the unipolar system.
As mentioned above, there is a drawback that a simple damping circuit cannot be constructed.

[Object of the Invention] The present invention has been made in view of the above points, and its object is to provide a damping circuit for a bipolar drive type step motor with an extremely simple circuit configuration.

[Disclosure of the Invention 1] A damping circuit for a step motor according to the present invention is a bipolar drive type step motor configured to alternately switch the current direction of the stator coil, and the input end of a full-wave rectifier circuit is connected to both ends of the stator coil. In addition, a switching element is connected to the output end of the full-wave rectifier circuit via a resistor, and this switching element is configured to conduct for 12 hours with a delay of t1 from the rise of each pole of each phase of the motor drive pulse. It is characterized by
The combination of a full-wave rectifier circuit and a switching element simultaneously protects and damps the transistor of the stator coil which is excited in both directions.

The present invention will be described in detail below based on the embodiment shown in FIG. In the figure, DRV is a conventional bipolar drive circuit, which is a circuit similar to that in FIG. 2(a), constructed using a microprocessor. La and Lb are A-phase and B-phase stator coils, respectively. The input terminals of full-wave rectifier circuits Ba and Bb are connected to both ends of each fill La and Lb, and the output terminal of each full-wave rectifier circuit Ba and Bb is connected to the input terminals of full-wave rectifier circuits Ba and Bb. The damping resistors Ra and Rb are connected in series with switching elements (in this embodiment, Darlington transistors Qa and Q+). Each switching element Qa and Qb is controlled by a control circuit CNT to be conductive for a certain period of time for each step.

Figure 3(a) shows a circuit example of the control circuit CNT, in which the A-phase or B-phase coil excitation voltage is passed through a differentiating circuit DE and then added to an OR circuit, and pulses are generated at the rising edge of each pole of each phase. By obtaining a1 and s and passing them through a monostable multivibrator M1 for a t1 time delay and a monostable multivibrator M2 for a 2 time delay,
Control signals a2 and b2 as shown in FIG. 2(b) are obtained.

[Effect of the invention 1] According to the above configuration, the exciting current of each stator coil flows through the path shown in FIG. In addition to being able to attenuate current, it also has the advantage of allowing the use of directional transistors, FETs, etc. because current always flows in one direction through the switching elements. Further, since two monostable multi-by-breaks are provided and the switching elements are brought into conduction after a certain time delay from the rise of the motor drive pulse, more effective damping can be achieved. In other words, Fig. 6 (
One monostable multivibrator M1 as shown in a)
When the switching element is turned on from the rising edge of the motor drive pulse using There is a problem that the rise of the coil excitation current is slow, so the response speed is not much improved, but according to the configuration of the present invention, the switching element is made conductive for only 12 hours 11 hours after the rise of the motor drive pulse. , as shown in Figure 5(b), when the rise is 1), it maintains the same steepness as in the figure without damping (,), and after the rise, a damping resistor is inserted and the oscillating current This has the advantage of improving the responsiveness of the step motor, eliminating vibration, and improving stability of operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 (
, ) is a schematic circuit diagram of the same drive circuit as above, FIG. 3(b) and (c) are waveform diagrams of each part in FIG. ) is a waveform diagram of each part in the figure (,), Figures 4 (,) and (b) are explanatory diagrams of the same operation as above, and Figure 5 is a graph of the rotation angle of the rotor.
) is without damping, (b) is with the present invention, (
c) shows the case of FIG. 6, and FIG. 6 is a reference diagram for explaining the present invention in detail, (a) is a block diagram of the control circuit, (b) is a waveform diagram according to the above, FIG. 7 is a circuit diagram of a main part of a conventional example. La and Ll) are stator filters, Ba and Bb are full-wave rectifier circuits, Ra and Rh are damping resistors, Qa
and Qb are switching elements, Ml and M2 are monostable multivibrators, D Rv is a drive circuit, and CNT is a control circuit. Agent Patent Attorney Ishi 1) Chief 7 Figure 1 Figure 3 ↓ (b) Figure 4 (G) (b) Figure 5 Figure 6 (b) □□□□□□□□□□□□□ □□□□□□□□□□□Special Publication Day HGO-237897 (5)

Claims (1)

[Claims] (1) In a bipolar drive step motor configured to alternately switch the current direction of the stator coil, the input ends of the aftereffect rectifier circuit are connected to both ends of the stator filter, and a resistor is connected to the output end of the full-wave rectifier circuit. 1. A damping circuit for a step motor, characterized in that a switching element is connected to the switching element via the motor drive pulse, and the switching element is made conductive for 17 hours one hour after the rise of a motor drive pulse.