JPS5911791A - Drive circuit for dc motor - Google Patents

Abstract

PURPOSE:To accurately obtain a proportional control for applied pulse width by adding a brake circuit which shortcircuits a drive current supply line when a DC motor is stopped, thereby almost eliminating the rotation of the motor due to inertia from the interruption of the energization of the drive current. CONSTITUTION:When a normal rotation command from normal/reverse rotation instructing circuit 5 and a pulse P1 of the prescribed width from a pulse generator 4 are applied to a pulse distributor 3, an output terminal 3A becomes ''H'', and the output terminal 3B becomes ''L'', transistors Q5, Q3, Q1 are turned ON, while transistors Q6, Q4, Q2 are turned OFF. Accordingly, the line X becomes ''H'', while Y becomes ''L'', and the DC motor A is normally rotated. When the pulse P1 of the prescribed width becomes OFF, the output terminals 3A, 3B of the pulse distributor 3 together become ''L'', and the drive current from a drive current amplifier 2 is stopped from supplying. On the other hand, the monostable circuit 8 of the brake circuit 6 is triggered at the trailing edge, the output terminals b1, b2 become ''H'', and the transistors Q1, Q2 are turned ON. Thus, the DC motor 1 is shortcircuited, a brake is operated to abruptly stop the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC motor drive circuit for driving a DC motor.

BACKGROUND ART Conventionally, as a method for driving a DC motor, there is a technique of controlling the four-wheel rotation by changing the duty ratio of pulses supplied to the motor.

This includes, for example, a pulse width generation circuit 4 as shown in FIG.
Forward/reverse command circuit 5, pulse distribution circuit 6, drive amplifier 2A
, 2B, which drives pulses from the pulse width generation circuit 4 based on the forward/reverse signal from the forward/reverse command circuit 5.

2B to rotate the DC motor 1 forward or reverse, respectively. That is, when it is desired to rotate the motor 1 in the normal direction, the two drive amplifiers are selected by outputting a normal rotation signal from the forward/reverse rotation command circuit 5 to rotate the DC motor 1 in the normal direction, and when the motor 1 is desired to be rotated in the reverse direction, the drive amplifier 2B is selected. The DC motor is selectively reversed.

Now, as shown in FIG. 2, the purpose of such technology is to obtain a rotation amount of the motor 1 that is proportional to the width of the pulse (this becomes the drive current) applied to the DC motor 1.
Normally, the DC motor 1 has inertia, so the amount of rotation cannot be controlled with high precision using conventional techniques. That is, as shown in FIG. 2, even if the energization to the DC motor 1 is stopped at time t5, the rotation of the DC motor 1 does not stop due to inertia during the time t5, so it ends up rotating an additional amount of rotation A. The amount of rotation A due to inertia depends on the rotational speed of the DC motor 1, the level of voltage applied to the DC motor 1, the size of the load,
Since the amount of rotation varies depending on the width of the pulse, it was not possible to obtain a rotation amount proportional to the width of the applied pulse.

In view of the above, it is an object of the present invention to provide a DC motor drive circuit that can reduce the amount of rotation of the DC motor due to inertia and perform accurate proportional control with respect to an applied pulse of 1'M. be.

Hereinafter, one embodiment of the present invention will be described in detail from FIG. 1.

First, in FIG. 6 showing the overall configuration, 1 is a DC motor, 2 is a drive amplifier, 5 is a pulse distribution circuit, 4 is a pulse generation circuit, and 5 is a forward/reverse command circuit. These have the same structure as the conventional one shown in FIG. 1, and in this example, in addition to this structure, a brake circuit 6 is newly added.

The pulse generating circuit 4 has a 1 m path for setting the drive time of the DC motor 1, and is configured to output pulses with different duty ratios as desired, as shown in FIG. 5(A). Therefore, when the pulse shown in FIG. 5 P1 is output from the pulse generating circuit 4, the DC motor 1 can rotate for the time t1 during which the pulse P1 is on.

Forward/reverse command circuit 5 pieces In the first cycle for outputting a signal for forward or reverse rotation of the DC motor 1 to the pulse distribution circuit 3, a high level (hereinafter referred to as H) No. 1d and a low level (hereinafter referred to as H) are output. The configuration is such that signals corresponding to the forward rotation and reverse rotation of the DC motor 1 are supplied to the pulse distribution circuit 6, respectively.

The MiJ pulse generation circuit 4 and the forward/reverse rotation command circuit 5 are controlled by, for example, a control circuit (not shown).

The pulse distribution circuit 6 is configured to set one of the output terminals 6A, 3E to H and the other to L based on the signals from the pulse generating circuit 4 and the forward/reverse command circuit 5. For example, an H signal instructing forward rotation is output from the forward/reverse rotation command circuit 5,
And the pulse P shown in FIG. 5(a) from the pulse generating circuit 4
When 1 is output, the output terminal 6A is set to t1 time, and the output terminal 6B is set to t1 time.

The drive amplifier 2 includes a switching circuit mainly composed of four transistors Q1 to Q4, and two transistors Q5.
．． It consists of an amplifier circuit mainly composed of Q6.

As shown in FIG. 4, the brake circuit 6 includes a monostable circuit 8 consisting of a capacitor C1 and a resistor R%NOT element 7, a diode DI for branching the output from this monostable circuit 8,
D2.

The input side a of this brake circuit B is the pulse generating circuit 4.
The output side b1.1)2 of the brake circuit B is connected to the output IA of the brake circuit B, and the output side b1.1)2 of the brake circuit B is connected to the bake B1. They are respectively connected to B2.

In the above configuration, when a forward rotation command is given to the pulse distribution circuit 6 from the forward/reverse command circuit 5, the pulse generation circuit 4 generates a pulse P1 of a predetermined width as shown in FIG. When the pulse distribution circuit 6 is applied, its output terminal 3A is set to H and its output terminal 3B is set to L while the pulse P1 is applied.

Then, transistor Q, 5 turns on, and transistor Q
, 6 are turned off, transistors Q1°Q, 3 are turned on, and transistors Q2. Q, 4 is turned off.

For this reason, transistor Q2. Since the line X1l-1:H connected to the emitter of transistor Q3 and the line Y connected to the emitters of transistors Q1 to Q4 become L, the DC motor 1 starts rotating forward.

Next, when time t1 has elapsed since this pulse P1 was output from the pulse generating circuit 4, the pulse P1 is turned off (this corresponds to time t2).

Then, the output J terminals 3A and 5B of the pulse distribution circuit both become L, so the supply of current from the drive amplifier 2 to the DC motor 1 is stopped.

On the other hand, since the output signal from the pulse generating circuit 4 is input to the brake circuit 6, when the Mjj pulse P1 is turned off, the monostable circuit 8 of the brake circuit 6 is turned off to FiIJ.
Triggered by the trailing edge of pulse P1, its output i+1)
1.1) 2 becomes H. For this reason, Towonjinuta Q1.
Q and 2 are turned on, and the lines X and Y of the DC motor 1 are short-circuited.

That is, if the DC motor 1 rotates even a little due to inertia after the pulse ends, the DC motor 1 generates a DC voltage as a DC generator. Therefore, if the current supply lines X and Y are short-circuited immediately after the pulse ends, a torque that stops the rotation of the motor will be generated, so the DC motor 1 can be stopped immediately.

Thereafter, when a predetermined time t6 determined by the resistive current and the capacitor C has elapsed, the monostable circuit 8 is inverted and turned off as shown in FIG. 5(b). Therefore, the short circuit between the lines X and Y is released and preparations can be made for the arrival of the next pulse P2.

Note that the brake circuit 6 may be configured without the resistor B and capacitor C. In this configuration, the brake circuit 6 becomes an inverting circuit mainly composed of the NOT element 7, and therefore, as shown in FIG.

This will short-circuit Y. Also, the output of the brake circuit 6 (11111) 1. Of course b2 is the pace of Tofunjista Q 3-, -Q 4 B3. It can also be connected to B4O11.

As explained above, in the present invention, a brake circuit is attached to the DC motor drive circuit to short-circuit the line for supplying current to the DC motor when the DC motor stops. A major feature is that rotation due to the inertia of the DC motor can be almost completely eliminated. For this reason, it is possible to control the rotation amount of the DC motor in proportion to the varne width from the pulse generation circuit, which eliminates the need for a position detector when controlling the rotation amount of the DC motor. It also has very favorable features as a drive circuit.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional DC motor drive circuit, Fig. 2 is an explanatory diagram showing the operating characteristics of a DC motor by a conventional DC motor drive circuit, and Fig. 6 is a primary current motor drive circuit according to the present invention. A block diagram showing one embodiment of the brake circuit, FIG. 4 is a circuit diagram showing one embodiment of the brake circuit, and FIG. 5 (A)
is an explanatory diagram showing the output waveform from the pulse generation circuit, Figure 5 (b) is an explanatory diagram showing the output waveform from the brake circuit, and Figure 5 (c) is the output waveform when the brake circuit is configured as an inverter circuit. FIG. 1...DC motor 2...Drive amplifier 6...
Pulse distribution circuit 4...Pulse generation circuit 5...Forward/reverse command circuit 6...For brake circuit Application
Aisan Industries Co., Ltd. Representative Patent Attorney Oka 1) Hide
Hiko45 2B Figure 2 s tg Time - Figure b

Claims (1)

[Claims] A DC motor, a pulse generation circuit that generates pulses to instruct the operation of the DC motor, a forward/reverse command circuit that outputs command signals for forward and reverse rotation of the DC motor, and signals from the forward/reverse command circuit. A DC motor drive circuit comprising a pulse distribution circuit that distributes pulses from the pulse generation circuit based on the above, and a drive amplifier that controls supply of current to the DC motor in forward and reverse directions using the pulses distributed thereby. A DC motor drive circuit, characterized in that a brake circuit that short-circuits a current supply line of the DC motor when the DC motor stops serves some purpose.