JPH06225585A - Conduction control circuit for motor - Google Patents

Abstract

PURPOSE:To obtain a conduction control circuit for a small-sized low-cost motor by providing conduction control means for stopping energization of the motor for a predetermined time when a motor current exceeding a reference value is detected and restarting after a predetermined time is elapsed. CONSTITUTION:A one-shot multivibrator 5 is arranged between a conduction stop transistor Q2 and a comparator 3 to turn ON the comparator 3 by inversion when a motor current I is increased when a motor 1 is started to exceed a reference current thereby to operate the multivibrator 5, thereby turning ON the transistor Q2 during an operating time. After an OFF operation delay time is elapsed, a control transistor Q1 is turned OFF, the motor current I flows through a flywheel diode 4 during the operating time of the multivibrator 5 to be reduced. When the operating time is elapse, the transistor Q2 is turned OFF, and the current I again flows after an ON delay time. As a result, a control element can be reduced in capacity and the circuit can be reduced in size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor energization control circuit.

[0002]

2. Description of the Related Art In a conventional motor, in order to protect the motor itself, a motor control circuit, etc., the motor current supplied to the motor is detected, and when the motor current exceeds a reference value, For example, an energization control circuit as shown in FIG. 4 is provided to stop energization.

Here, in FIG. 1, a motor 1 includes a control transistor Q1 which is a control element switched by a motor control circuit (hereinafter referred to as a control circuit) 2 which controls driving of the motor 1 and the like. It is connected in series with a detection resistor R which is a motor current detection means for detecting the current I.

When a motor drive signal is input to the control circuit 1 by operating a switch (not shown) or the like,
The control circuit 2 turns on the control transistor Q1 so that the motor 1 is energized and the motor 1 starts driving.

On the other hand, the detection resistor R is connected to a comparator 3, which has a reference voltage Vref.
And the voltage drop in the detection resistor R are compared, and when the voltage drop is smaller than the reference voltage Vref, it is turned off, and the energization stopping transistor Q2 connected to the comparator 3 is turned off. In addition,
When the energization stopping transistor Q2 is off, the control transistor Q1 remains on and the motor 1 continues to be energized.

However, when the motor current I exceeds the reference value for some reason and the voltage drop becomes larger than the reference voltage Vref, the comparator 3 reverses and becomes O.
Then, the power supply stop transistor Q2 is turned on.

In this case, the control transistor Q1 is turned off even though the control circuit 2 is operating.
Then, the power supply to the motor 1 is stopped. In addition, 4 is connected in parallel with the motor 1 and the O of the control transistor Q1 is
A flywheel diode for biasing the motor current I during FF.

[0008]

By the way, in such a conventional motor energization control circuit, when the motor is started,
As shown in FIG. 5, a starting current Ip having a magnitude close to the constraint flows through the control transistor. It should be noted that the starting current Ip decreases as the number of revolutions of the motor increases after starting the motor, and eventually reaches the rated current Ic, as shown in FIG.

Since the starting current Ip flows more than 10 times the rated current Ic depending on the type of motor,
In order to withstand this, the control transistor has a large capacity, and accordingly, there has been a problem that the energization control circuit becomes large and the price becomes expensive.

Therefore, conventionally, for example, a current (hereinafter referred to as a reference current) Ia for inverting a comparator is used as a starting current I.
There is a device in which the capacitance of the control transistor is set to be smaller than p so as to reduce the capacitance thereof.

By the way, in the case of such an energization control circuit, as shown in FIG. 6, after a fixed delay time (hereinafter referred to as OFF operation delay time) T1 has elapsed since the comparator was inverted and turned on, the control circuit is controlled. Since the transistor is turned off, the motor current I remains even after the comparator is turned on.
Is further increased by the OFF operation delay time T1.

When the control transistor is turned off, the voltage drop of the detection resistor R becomes 0 and the comparator is inverted again to be turned off. As a result, the comparator is turned off again and a certain delay time (hereinafter, turned on). After a lapse of T2 (referred to as operation delay time), the control transistor is turned on and the motor current I starts to flow again.

The motor current I is bypassed by the flywheel diode 4 while the control transistor is off, and the control transistor is turned on again.
When it starts to flow, it decreases as shown by the broken line in the figure.

Here, comparing the motor current I decreasing during the ON delay time T2 and the motor current I increasing during the OFF operation delay time T1, the increasing motor current I is larger. The motor current I increases even though the energization control circuit is operating. For this reason, the energization control circuit having such a configuration can be used only when the starting current I
There is a problem that only the motor having a small difference between p and the rated current Ic cannot be used for other motors.

An object of the present invention is to provide a small-sized and inexpensive motor energization control circuit.

[0016]

According to the present invention, there is provided a motor current detecting means for detecting a motor current supplied to a motor, and the motor current detecting means detects the motor current exceeding a reference value. To a value less than or equal to the reference value, and the energization control means for stopping the energization of the motor for a predetermined time and restarting the energization after the elapse of the predetermined time.

The present invention also provides, as the energization control means,
It uses a one-shot vibrator.

Further, according to the present invention, there is provided a motor current detecting means for detecting a motor current supplied to the motor, and when the motor current detecting means detects a motor current exceeding a reference value, the motor current is set to a reference value or less. The motor starting means for stopping the energization of the motor for a predetermined time sufficient to operate the motor and repeating the operation of resuming the energization after a predetermined time to start the motor, and measuring the time from the start, and elapses a predetermined time And a motor protection unit for stopping the energization of the motor when the motor current detection unit later detects a motor current exceeding a reference value.

[0019]

With this configuration, when the motor current detecting means detects the motor current exceeding the reference value, the one-shot vibrator as the energization control means supplies the motor current for a predetermined time sufficient to keep the motor current below the reference value. The energization can be stopped to reduce the motor current below the reference value. In addition, after a lapse of a predetermined time, the energization can be restarted.

When the motor current detecting means detects a motor current exceeding the reference value, the one-shot vibrator stops the energization of the motor for a predetermined time sufficient to keep the motor current below the reference value, and the motor current is stopped. Is reduced to a reference value or less, and the motor can be started by the motor starting means that repeats the operation of restarting the energization after the lapse of a predetermined time.

When a motor current exceeding the reference value is detected by the motor current detecting means after a lapse of a certain time from the start-up, the motor protection means can stop the energization of the motor.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of a motor energization control circuit according to an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 4 indicate the same or corresponding parts.

In the figure, numeral 5 is a one-shot vibrator (hereinafter referred to as one-shot) which is an energization control means. This one-shot 5 is an energization stopping transistor Q.
2 is placed between the comparator 3 and the normal OF
When the comparator 3, which is F, is inverted and turned on, the energization stopping transistor Q2 is turned on and the control transistor Q1 is turned off regardless of the output state of the control circuit 2 for a predetermined operation time T3. Is.

The reference current Ia is set to a value larger than the rated current Ic shown in FIG. 5 and smaller than the starting current Ip, and when the motor 1 is started, the motor current I increases to increase the reference current Ia. When it exceeds, the comparator 3 is inverted and turned on, and the one-shot 5 is activated to turn on the energization stopping transistor Q2.

Then, along with this, the motor current I is shown in FIG.
After being increased by the OFF operation delay time T1 as shown in (3), it flows through the flywheel diode 4 for the operation time T3 of the one-shot 5 and decreases as shown by the broken line in the figure. Further, even after the operation time T3 has passed and the energization stopping transistor Q2 is turned off,
It continues to decrease until the N delay time T2 elapses, and increases again when the control transistor Q1 is turned on.

Here, the operating time T of this one-shot 5
3 is turned off after the motor current I, which has begun to flow again in this way, exceeds the reference current Ia and is stopped again.
The current value I2 when the operation delay time T1 has elapsed is set to be smaller than the current value I1 at the last OFF operation delay time T1. In other words, the control transistor Q1 is turned off to stop the energization of the motor 1 so that the motor current I is set to the reference current Ia or less.

As a result, when the one-shot 5 is activated and the ON delay time T2 elapses and then the control transistor Q1 is turned ON, the motor current I decreased during that period.
Is again increased and exceeds the reference current Ia, the control transistor Q1 is turned off after the OFF operation delay time T1, but the current value I2 at this time is smaller than the current value I1 when it was turned off last time. Will be things.

In the energization control circuit configured as described above, when the motor 1 is started by the drive signal and the motor current I increases and exceeds the reference current Ia, the comparator 3 is inverted and turned on, and the one-shot. 5 operates to turn on the energization stopping transistor Q2 during the operation time T3.

As a result, as shown in FIG. 2, after the OFF operation delay time T1 has elapsed, the control transistor Q1 is turned OFF, and accordingly, the motor current I becomes the flywheel diode 4 during the operation time T3 of the one shot 5. Flow through and decrease as shown by the broken line.

Eventually, when the operating time T3 elapses, the energization stopping transistor Q2 is turned off, and the ON delay time T
After 2, the motor current I flows again. After that, when the decreased motor current I increases again and exceeds the reference current Ia, O
After the FF operation delay time T1, the control transistor Q1 becomes O.
FF, but the current value I2 of the motor current I at this time is
It becomes smaller than the current value I1 when it was turned off last time.

In this way, the O of the control transistor Q1 is
Even if the motor current I flows again and increases the FF time, the capacitance of the control transistor Q1 is made to correspond to the reference current Ia instead of the starting current Ip by not exceeding the current value I1 that was previously turned OFF. Therefore, the control transistor Q1 having a small capacity can be used. In addition, since the energization can be stopped when the reference current Ia is exceeded, even when a problem such as a motor lock occurs, the motor 1 can be stopped.
It is possible to prevent an overcurrent from flowing in the above.

By the way, the energization control circuit described so far protects the motor and the like by temporarily stopping energization to the motor when an overcurrent flows during normal operation as well as during motor startup. The present invention is not limited to this,
When an overcurrent flows after the motor is started, the motor and the like can be protected by not energizing the motor thereafter.

FIG. 3 is a circuit diagram of a motor energization control circuit according to another embodiment of the present invention. In the figure, 6 is an energization time measurement circuit connected to the control circuit 2 for measuring the energization time after the motor 1 is started. In addition,
The output of the comparator 3 is also input to the control circuit 2.

The control circuit 2 constitutes a motor protection means together with the energization time measuring circuit 6, and the comparator 3 is inverted based on the time information of the time measuring circuit 6 before the lapse of a fixed time from the start of the motor 1. When it is turned on, it is determined that it is in the activated state, and the control transistor Q already described.
The ON / OFF operation of 1 is repeated to start the motor 1.

Further, based on the time information of the time measuring circuit 6, when the comparator 3 is turned on after a lapse of a certain time from the start-up of the motor 1, it is judged that it is not in the start-up state and thereafter the control transistor Q1 is connected. The power is turned off.

As a result, when an overcurrent flows after the motor 1 is started, the motor 1 is no longer energized and the motor 1
Etc. can be protected and the state at the time of overcurrent generation is maintained, so that accurate abnormality detection can be performed.

In the above description, the motor using the transistor as the control element has been described, but the present invention is not limited to this, and other control elements such as a three-phase brushless motor such as an FET and a thyristor may be used. It can be applied to all kinds of devices as long as they are used to control energization of a motor.

[0039]

As described above, according to the present invention, when the motor current exceeds the reference value, the energization of the motor is stopped for a predetermined time, and after the energization is resumed, the current value of the motor current which was turned off last time. Since the energization can be controlled so as not to exceed the limit, the capacity of the control element and the size of the circuit can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a motor energization control circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing how the motor current of the energization control circuit changes.

FIG. 3 is a circuit diagram of a motor energization control circuit according to another embodiment of the present invention.

FIG. 4 is a circuit diagram of a conventional energization control circuit.

FIG. 5 is a diagram showing a change in motor current from the start.

FIG. 6 is a diagram showing how the motor current of a conventional energization control circuit changes.

[Explanation of symbols]

 1 Motor 5 One-shot vibrator 6 Energization time measurement circuit Q1 Control transistor Q2 Energization stop transistor R Detection resistor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Matsumoto 2-18 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (72) Inventor Hiroyasu Ishihara 2-18, Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. Within the corporation

Claims (3)

[Claims] 1. A motor current detecting means for detecting a motor current supplied to a motor, and a motor current detecting means for detecting a motor current exceeding a reference value is sufficient to set the motor current to a reference value or less. An energization control circuit for a motor, comprising: energization control means for stopping energization of the motor for a predetermined time and resuming energization after a lapse of a predetermined time. 2. The motor energization control circuit according to claim 1, wherein a one-shot vibrator is used as the energization control means. 3. A motor current detecting means for detecting a motor current supplied to the motor, and a motor current detecting means for detecting a motor current exceeding a reference value is sufficient to keep the motor current below a reference value. The motor starting means for starting the motor by repeating the operation of stopping the energization of the motor for a predetermined time and restarting the energization after the elapse of the predetermined time, and measuring the time from the start, An energization control circuit for a motor, comprising: a motor protection unit that stops energization of the motor when a motor current exceeding a reference value is detected by the current detection unit.