JPS6139898A - High speed drive circuit for stepping motor - Google Patents

Abstract

PURPOSE:To enable to drive a stepping motor at a high speed by providing a switch circuit for breaking a reverse exciting current generated by mutual induction. CONSTITUTION:In order to break a reverse exciting current for causing a motor winding to excite in a direction for disturbing the rotation of the motor, generated by mutual induction, bias resistors 17, 19, 20, 22, 23, 25, 26, 28 and transistors 18, 21, 24, 27 are added. Thus, a current passage formed of the transistor 21, a motor winding 4, a diode 10 and an absorbing resistor 7 is interrupted by the OFF of the transistor 21 in the motor winding 4 through which, for example, a reverse exciting current is heretofore flowed. Accordingly, the reverse exciting current does not flow to enable high speed drive.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a stepping motor high-speed drive circuit, and more particularly to a stepping motor high-speed drive circuit suitable for enabling high-speed drive while maintaining a half-step drive function. It is something.

[Background of the invention]

The problem when driving a stepping motor at high speed is (1
) To shorten the delay in the rise time of the current defined by the time constant T (=L/R) determined by the inductance L of the motor coil and the winding resistance R.

(2) Eliminate the reverse excitation phenomenon due to mutual induction between motor coils.

It is. Regarding (1), there are methods to increase the absolute value of the current by applying a high voltage to the stepping motor, and methods to change the time constant by adjusting the resistance value of an external resistor. It puts a strain on the equipment,
In addition, consideration must be given to heat dissipation from the motor, and furthermore, a special element with a high reverse voltage resistance must be used as the switching element. Regarding the latter, external resistance has the disadvantage that power consumption by the resistor is considerably large, resulting in poor efficiency. Regarding (2), it is possible to solve the problem from the structure of the motor body, such as changing the winding method of the motor coil, but this will increase the cost due to the increase in size due to the complexity of the structure or constraints from the precision aspect of processing. There are drawbacks that cannot be avoided. Therefore, improvements to the drive circuit are required, and for this reason, a bipolar drive system has generally been adopted.

FIG. 1 is a circuit diagram of a conventional bipolar stepping motor drive circuit. Although a description of the circuit configuration in FIG. 1 will be omitted, in FIG. Since it follows the switching thetance as shown in Figure 2, it is the same as the normal two-phase excitation method.Therefore, when the reverse excitation current generated by mutual induction should flow, this reverse excitation current is forced to flow. A canceling current flows, and as a result, a large amount of effective current flows, allowing high-speed driving.

However, since it can only be driven with the same sequence as in the case of two-phase excitation, in order to obtain a resolution of (N'/2) steps/pulses using a stepping motor with N0 steps/pulses, it is necessary to use N0 steps/pulses. It is necessary to use a four-phase stepping Tanabata pulse, which requires one more set of drive circuits as shown in FIG. 1, which has the disadvantage of complicating the circuit configuration.

FIG. 3 is a circuit diagram of a conventional unipolar stepping motor drive circuit. In Fig. 3, 3.4 is the A-phase motor winding of the stepping motor, 5.6 is the B-phase motor winding, 7 is an absorption resistor, 8 is a capacitor, 9 to 12 are diodes, and 13 to 16 are It is a transistor. According to FIG. 3, half-step driving is possible using the 1-2 phase excitation sequence shown in FIG. resolution can be obtained. However, the fifth
As shown in the figure, in the low speed range, each phase has a sufficiently large current 1. -I4 flows, but when entering the high speed range, as shown in FIG. 6, there is insufficient time for the currents in each of the phase currents 1 to 4 to rise, and the absolute value of the flowing current decreases. In addition, a reverse excitation current flows, and the output torque of the stepping motor is considerably reduced. FIG. 7 is an enlarged view of a part of FIG. 6, and in period T1, the A-phase current II becomes the effective current.
During period T3, a reverse excitation current circulates through the coil 3, diode 9, and resistor 7, and prevents the stepping motor from rotating. Therefore, the effective current flowing through the human phase during the period TI is approximately expressed as (, II I2), and is only the shaded portion in FIG. 7, resulting in a considerable decrease in the effective current. This decrease in current causes a decrease in motor torque, posing a problem in that high-speed drive becomes impossible.

As mentioned above, the conventionally used bipolar system is capable of high-speed driving, but the circuit configuration is complicated, while the unipolar system has a simple circuit, but is capable of reverse excitation in the high-speed range. The drawback was that it generated a current and was not suitable for high-speed driving.

[Purpose of the invention]

The present invention has been made in view of the above, and its purpose is to maintain the half-step drive function, and to
An object of the present invention is to provide a high-speed stepping motor drive circuit that is an improved version of a unipolar system capable of high-speed drive.

[Summary of the invention]

The present invention is characterized in that a switching circuit is provided to cut off the reverse excitation current, which has been a problem with conventional unipolar drive circuits.

[Embodiments of the invention]

The present invention will be explained in detail below using the embodiment shown in FIG.

FIG. 8 is a circuit diagram showing an embodiment of the stepping motor high speed drive circuit of the present invention. In Figure 8, ur-13,
4 is an A-phase motor winding of the stepping motor, 5 and 6 are B-phase motor windings, 7 is an absorption resistor, 8 is a capacitor, 9 to 12 are diodes, and 13 to 16 are transistors. By the way, in the present invention, the bias resistors 17, 19, 20, 22, 23 are used in order to cut off the reverse excitation current that causes the motor winding to be excited in a direction that prevents the motor rotation, which occurs due to mutual induction.゜25
．． 26, 28, and transistors 18, 21, and 24, 27 are added, and these are connected as shown. In addition, since Fig. 8 basically has a unipolar system configuration, the 1-2 phase excitation sequence signal shown in Fig. 4 is inputted.
-7 step drive is possible.

The excitation operation of the A-phase motor windings 3 and 4 will be described below with reference to FIG. According to the 1-2 phase excitation sequence shown in FIG. 4, when a 1H# level signal is input from terminal Dm to the base of transistor 13,
turns on. At this time, as is clear from FIG. 4, since the ""L#L# level is input to the terminal, the base of the transistor 18 becomes a low potential, the transistor 13 is also turned on, and the power supply VM supplies the transistor 18, a current flows to the motor winding 3 and the transistor 13, and an excitation current flows to the motor winding 3. - 10,000, since the base of the transistor 13 maintains a high potential, the transistor 21 is in an off state, and the motor winding 4 through which reverse excitation current conventionally flows has the transistor 21, the motor winding 4, the diode 10,
The current path formed by the absorption resistor 7 is the transistor 2
1 is turned off, so no reverse excitation current flows. Next, when the input signal of the terminal D becomes "L# level", the transistor 13 turns off, but the human phase current does not suddenly become zero, so the diode 9, absorption resistor 7, transistor 18, and motor winding 3, it flows in the form of a damping current and gradually attenuates.Then, when the input signal at the terminal D becomes "H" level, the transistor 14 is turned on, and at the same time, the input signal at the terminal DA becomes "L". '' level, the transistor 21 is also turned on, and the transistor 21.14 is connected to the motor winding 4.
The excitation current flows through. On the other hand, since the base of the transistor 14 is at a high potential, the transistor 18 is turned off, and the reverse excitation current flowing through the motor winding 3 is cut off. When the input signal of the terminal DA becomes @L'' level, the transistor 14 is turned off, and the excitation current of the motor winding 4 damps the current path consisting of the motor winding 4, the diode 10, the absorption resistor 7, and the transistor 21. It flows as a current and gradually attenuates.The same operation is repeated thereafter.The same applies to the excitation operation of the B-phase motor windings 5 and 6.

As described above, according to the embodiment of the present invention, a bias resistor 17° 19.20, 22, 2 for cutting off reverse excitation current is added to the conventional unipolar stepping motor drive circuit.
3, 25, 26.28 and transistor 8.21, 24
．． Since the switching circuit consisting of 27 is added, the half-step drive function is maintained and high-speed drive is possible.

In the embodiment shown in FIG. 8, transistors 18, 21 .・24.2
7 is used, but this is not limited to transistors, and may be constructed from other conductive switches such as SIRISK or mechanical switches such as relays. Also, the 8th
It goes without saying that the drive circuit shown in the figure can also be applied to driving a polyphase motor.

〔Effect of the invention〕

As explained above, according to the present invention, there is an effect that the half-step drive function is maintained and high-speed drive is possible.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional bipolar stepping motor drive circuit, Figure 2 is a two-phase excitation sequence diagram, Figure 3 is a circuit diagram of a conventional unipolar stepping motor drive circuit, and Figure 4 is a circuit diagram of a conventional unipolar stepping motor drive circuit. -Two-phase excitation sequence diagram, Figure 5 is a winding current waveform diagram at low speed when the signal in Figure 4 is input to the circuit in Figure 3, and Figure 6 is the winding current waveform at high speed. Figure 7 is a partially enlarged view of Figure 6 and effective current theory 8A diagram, #! FIG. 8 is a circuit diagram showing an embodiment of the stepping motor high speed drive circuit of the present invention. 3.4, 5.6... Motor winding, 7... Absorption resistance,
8... Capacitor, 9-12... Diode, 13
~16.18,21,24.27...transistor,
17.19,20,22,23,25,26゜So /I Appetizer 2m IK

Claims (1)

[Claims] 1. A unipolar stepping motor drive circuit, characterized in that it is equipped with a switch circuit that cuts off a reverse excitation current that causes the motor windings to be excited in a direction that prevents motor rotation caused by mutual induction. Ping motor high speed drive circuit.