JPH099671A - Control circuit for dc brushless motor - Google Patents

Abstract

PURPOSE: To constitute a control circuit on one board without an outer connection lead using a simple program for a microcomputer, by comparing a detected current of a DC brushless motor with a reference voltage and detecting a locked state in the DC brushless motor. CONSTITUTION: A motor driving means 2 drives a DC brushless motor 1, and a current detection means 3 detects a current in the DC brushless motor 1 which flows through the motor driving means 2. A reference voltage is set by a reference voltage setting means 4, and an output signal from the current detection means 3 and an output signal from the reference voltage setting means 4 are compared by using a comparing means 5. A control means 8 generates a signal to the motor driving means 2. The output signal of the comparing means 5 is entered in the control means 8 and when the DC brushless motor 1 is locked, the control means 8 generates a signal to a display circuit 6. The locked state is displayed and at the same time a load circuit 7 is stopped under control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC brushless motor control circuit mainly used for cooling electronic devices and the like.

[0002]

2. Description of the Related Art In recent years, high-power electronic devices have become popular, and electronic devices having a fan for cooling an electronic control circuit have become mainstream inside the electronic devices.

A block diagram of a control circuit of a conventional DC brushless motor is shown in FIG. FIG. 9 shows a concrete example of the control circuit of the conventional DC brushless motor. Further, FIG. 10 shows voltage waveforms at various parts of the control circuit of the conventional DC brushless motor.

The structure and operation will be described below with reference to FIGS.
Description will be given with reference to 0. As shown in FIG. 8, a block diagram of a control circuit of a conventional DC brushless motor is shown as follows: a DC brushless motor 80 with a fan and a motor driving means 81 for driving the DC brushless motor 80. Rotation detecting means 82 for detecting the rotation of the DC brushless motor 80.
And the output signal of the rotation detection means 82 as an input, and outputs a signal to the load circuit 83 other than the DC brushless motor 80 and the motor drive means 81 to load the load when the DC brushless motor 80 is locked. And a control means 84 for controlling the circuit 83 to stop.

Next, the structure of the control circuit of the conventional DC brushless motor shown in FIG. 9 will be described. Reference numeral 80 is a DC brushless motor with a fan, which is driven by a transistor 81b. In addition, a photo diode 82, which is arranged with a fan of the DC brushless motor 80 in between.
The rotation speed of the fan is detected by using a and the phototransistor 82b. The photo diode 82a and the phototransistor 82b are on a printed circuit board, and are connected to the printed circuit board having the microcomputer 84b by three connecting lines. A load circuit 83 is a load circuit other than the DC brushless motor 80. Reference numeral 84b is a microcomputer which outputs a signal to the transistor 81b and inputs the output signal of the resistor 82d to control the load circuit 83 to stop it when the DC brushless motor 80 is locked. Reference numeral 85 is an AC power source, and 86 is a DC motor power source, which generates a DC power source for the DC brushless motor 80. Reference numeral 87 is a power supply for a microcomputer, which is input with the power supply 86 for the DC motor and generates a 5V power supply.

The operation of the control circuit of the conventional DC brushless motor 80 shown in FIG. 9 will be described below with reference to FIG. First, the microcomputer 84b sets the output portion connected to one side of the resistor 81a and the base of the transistor 81b to the open state from the ground level to turn on the transistor 81b.
Is turned on to rotate the DC brushless motor 80.
At the same time, the microcomputer 84b has a resistor 8
The output section connected to 2c is changed from the open state to the ground level, a current is supplied to the photodiode 82a, and the load circuit 83 is operated according to the program stored in the storage section of the microcomputer 84b. Let When the DC brushless motor 80 is rotating normally, the resistance 82d, which is the output of the phototransistor 82b, is shown in FIG.
As shown in (a), a pulse corresponding to the number of revolutions of the DC brushless motor 80 of high level and ground level of about 5 V is generated and input to the input part of the microcomputer 84b. Thereby, the micro computer 84b
Determines that the DC brushless motor 80 is rotating normally, and continues the operation of the load circuit 83 according to the program stored in the storage unit. DC brushless motor 80
When the is locked, depending on the position where the fan is locked,
0 (b) and FIG. 10 (c), it becomes a high level or a ground level of about 5V.

That is, if the position where the fan is locked is the position where the current is passed through the photodiode 82a, the position shown in FIG.
0 (b) to a high level of about 5V, photodiode 8
At a position where no current is applied to 2a, the ground level is shown in FIG. The microcomputer 84b that receives this signal determines that the DC brushless motor 80 is locked and stops the operation of the load circuit 83. That is, the signal level when the DC brushless motor 80 is normally rotating is a pulse of a high level of about 5V and a ground level, and the signal level when the DC brushless motor 80 is locked is a high level of about 5V. Or, there are two types of ground level.

[0008]

The control circuit of such a conventional DC brushless motor 80 is composed of a substrate having the microcomputer 84b and a substrate having the rotation detecting means 82. Since it is necessary to connect with three or more connecting wires, there is a problem that material cost and work cost increase. In addition, there is a problem that the structure for fixing the substrate having the three or more connecting wires and the rotation detecting means 82 becomes complicated.

Further, since the pulse signal is output during normal rotation and either one of the two types of signals is output during lock, a program for processing is processed by the microcomputer 84b. There was a problem that it became complicated.

Further, when the DC brushless motor 80 is locked, the user cannot determine the reason why the load circuit 83 is stopped.

The present invention has been made to solve the above problems, and it is possible to reduce the number of connecting wires to simplify the structure, to reduce the material cost and the work cost, and to facilitate the processing in a micro computer. It has the first purpose.

Further, the number of connecting wires is reduced to simplify the structure, reduce the material cost and the working cost, facilitate the processing by the micro computer, and detect the locked state of the DC brushless motor. The second purpose is to further improve

A third object is to allow the user to easily determine the state of the DC brushless motor.

[0014]

SUMMARY OF THE INVENTION In order to achieve the first object, the present invention is a DC brushless motor with a fan.
Motor, a motor driving means for driving the DC brushless motor, a current detecting means for detecting a current of the DC brushless motor flowing in the motor driving means, and a reference voltage for setting a reference voltage. The control means comprises: setting means, comparing means for comparing two output signals of the current detecting means and the output signal of the reference voltage setting means, and control means for controlling the motor driving means. Is for detecting the locked state of the DC brushless motor by the output signal of the comparison means and controlling the load circuit.

In order to achieve the second object,
The present invention relates to a DC brushless motor with a fan, a motor driving means for driving the DC brushless motor, and a current for detecting a current of the DC brushless motor flowing through the motor driving means. Detecting means, reference voltage setting means for setting a reference voltage, comparing means for comparing two output signals of the output signal of the current detecting means and the output signal of the reference voltage setting means, and the output level of the comparing means. A voltage level holding means for holding for a predetermined time and a control means for controlling the motor driving means are provided, and the control means detects a lock state of the DC brushless motor by an output signal of the voltage level holding means and detects a load circuit. Is controlled.

Further, it is an object of the present invention to provide a display circuit for displaying the state of the DC brushless motor, in order to achieve the third object.

[0017]

The present invention has the above-mentioned structure and is a DC brushless motor.
The current of the DC brushless motor flowing through the motor driving means for driving the motor is detected, and the magnitude and the reference voltage are compared to detect the locked state of the DC brushless motor.
It can be composed of one board to eliminate the connecting line, the structure is simple and the material cost and work cost can be reduced, and one kind of signal is output when the DC brushless motor is locked. As a result, the program for processing by the microcomputer can be simplified.

Further, a voltage level holding means for holding the output level of the comparison means for a predetermined time is provided, and the lock state of the DC brushless motor is detected by the output of the voltage level holding means, so that the structure of one substrate is obtained. It is possible to eliminate the connection line, the structure is simple and the material cost and work cost can be reduced, and there is a margin in the level setting of the reference signal corresponding to the normal state and the locked state of the DC brushless motor. Since it can be held, it is possible to further improve the detection performance of the locked state of the DC brushless motor.

Further, by providing the display circuit, the user can easily understand the locked state of the DC brushless motor.

[0020]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is a DC brushless motor with a fan, and 2 is a motor driving means for driving the DC brushless motor 1. Reference numeral 3 is a current detecting means, which is a DC brushless motor flowing in the motor driving means 2.
The current of data 1 is detected. Reference numeral 4 is a reference voltage setting means for setting a reference voltage. Reference numeral 5 is a comparison means, which inputs the output signal of the current detection means 3 and the output signal of the reference voltage setting means 4 and compares the two output signals. 6
Is a display circuit and displays the state of the DC brushless motor 1. A load circuit 7 is a circuit other than the DC brushless motor 1. Reference numeral 8 is a control means which outputs a signal to the motor drive means 2 and inputs the output signal of the comparison means 5 to output a signal to the display circuit 6 when the DC brushless motor 1 is locked. Is displayed, and the load circuit 7 is controlled to be stopped.

In FIG. 2, 1 is a DC brushless motor with a fan, which is driven by a transistor 2b. Reference numeral 3 is a resistance as a current detecting means, which is a DC brushless motor 1 flowing in the transistor 2b.
Is detecting the current. A display circuit 6 displays the state of the DC brushless motor 1. Reference numeral 7 is a load circuit. Reference numeral 8b is a microcomputer which outputs a signal to the transistor 2b, inputs the output signal of the comparator 5a, outputs a signal to the display circuit 6 when the DC brushless motor 1 is locked, and displays it. At the same time, the load circuit 7 is controlled to stop. 9 is an AC power supply. Reference numeral 10 denotes a DC motor power source, which receives an AC power source 9 to generate a DC power source for the DC brushless motor 1. Reference numeral 11 is a power supply for a microcomputer, which is supplied with the power supply 10 for the DC motor and generates a 5V power supply.

The operation of the above structure will be described with reference to the voltage waveforms at the respective portions shown in FIGS. First, the micro computer 8b turns on the transistor 2b by turning on the transistor 2b by turning on one side of the resistor 2a and the output part connected to the base of the transistor 2b from the ground level to rotate the DC brushless motor 1. Let At the same time, the microcomputer 8b operates the load circuit 7 according to the program stored in the storage section. When the DC brushless motor 1 is rotating normally, the waveform as shown in FIG. 3 (a) is input to the non-inverting terminal of the comparator 5a.
Further, as shown in FIG. 3 (a), a reference voltage obtained by dividing the power source 11 for the microcomputer by the resistors 4a and 4b is input to the inverting terminal of the comparator 5a.
Therefore, at the output terminal of the comparator 5a, as shown in FIG. 3 (b), a pulse corresponding to the rotation speed and the excitation method of the DC brushless motor 1 at a high level and a ground level of about 5V is generated. When this signal is input to the microcomputer 8b, the microcomputer 8b determines that the DC brushless motor 1 is rotating normally, and the load circuit 7 is operated according to the program stored in the storage unit. Let it continue. When the DC brushless motor 1 is locked, the current flowing through the motor driving means 2 for driving the DC brushless motor 1 becomes large and a continuous DC current is obtained.
A voltage as shown in FIG. 3C is input to the non-inverting terminal of the comparator 5a. Further, as shown in FIG. 3 (c), a reference voltage obtained by dividing the power source 11 for the microcomputer by the resistor 4a and the resistor 4b is input to the inverting terminal of the comparator 5a. The output terminal of is at a high level of almost 5 V as shown in FIG. This signal is sent to the micro computer 8b.
Is input, the microcomputer 8b determines that the DC brushless motor is locked, displays this on the display circuit 6, and stops the operation of the load circuit 7. Next, depending on the characteristics of the DC brushless motor 1, the current
If the difference between the peak value and the peak value of the current when locked is large,
Microcomputer power source 1 with resistors 4a and 4b
If the reference voltage obtained by dividing 1 is set so as to be larger than the peak value of the waveform in the normal state and smaller than the peak value in the locked state, the output terminal of the comparator 5a in the normal state is also Can be almost at ground level.

This will be described with reference to FIG. When the DC brushless motor 1 is rotating normally, the comparator 5a
A waveform as shown in FIG. 4A is input to the non-inverting terminal of the. Further, as shown in FIG. 4A, a reference voltage obtained by dividing the power supply 11 for the microcomputer by the resistors 4a and 4b is input to the inverting terminal of the comparator 5a. This reference voltage is set to be sufficiently smaller than the peak value at the time of lock and larger than the peak value of the voltage waveform at the normal time, and the output terminal of the comparator 5a is shown in FIG.
As shown in (b), it is almost at the ground level. As a result, the microcomputer 8b determines that the DC brushless motor 1 is rotating normally, and continues the operation of the load circuit 7 according to the program stored in the storage unit. Further, when the DC brushless motor 1 is locked, the current flowing through the motor driving means 2 for driving the DC brushless motor 1 becomes large and a continuous DC current is produced, so that the comparator 5a is not inverted. Figure 4
The voltage as shown in (c) is input. Further, the inverting terminal of the comparator 5a is provided with a resistor 4a and a resistor 4b as shown in FIG.
The divided reference voltage is input. This reference voltage is set to be sufficiently smaller than the peak value at the time of lock and larger than the peak value of the voltage waveform at the normal time, and the output terminal of the comparator 5a is shown in FIG. As shown, it is almost at a high level of 5V. When this signal is input, the microcomputer 8b determines that the DC brushless motor 1 is locked, displays this on the display circuit 6, and stops the operation of the load circuit 7. Here, the control of the load circuit 7 is such that the operation is stopped after a certain period of time elapses.
It suffices if it can be controlled so that the electronic circuit is not destroyed.

As described above, the present invention is a DC brushless motor.
The current of the DC brushless motor 1 flowing through the motor driving means for driving the motor 1 is detected, and the magnitude of the current is compared with the reference voltage to detect the locked state of the DC brushless motor 1. It can be composed of a board, connection wires can be eliminated, the structure is simple, material cost and work cost can be reduced, and one kind of signal is output when the DC brushless motor 1 is locked. Therefore, when processing by the microcomputer 8b, the program for processing can be simplified. Further, the user can easily understand that the DC brushless motor 1 is locked.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIGS.

In FIG. 5, 20 is a DC brushless motor with a fan, and 21 is a motor driving means for driving the DC brushless motor 20. 22
Is a current detecting means for detecting the current of the DC brushless motor 20 flowing through the motor driving means 21. 23
Is a reference voltage setting means and sets a reference voltage.
Reference numeral 24 is a comparison means, which inputs the output signal of the current detection means 22 and the output signal of the reference voltage setting means 23 and compares two signals. A voltage level holding means 25 operates so as to hold the voltage level of the output signal of the comparing means 24. A display circuit 26 displays the state of the DC brushless motor 20. Reference numeral 28 is a control means which outputs a signal to the motor drive means 21 and inputs the output signal of the voltage level holding means 25 to the DC brushless motor 20.
When is locked, a signal is output to the display circuit 26 to display it and the load circuit 27 is controlled to stop.

Further, in FIG. 6, 20 is a DC brushless motor with a fan, which is driven by a transistor 21b. Reference numeral 22 denotes a resistor as a current detecting means, which detects the current of the DC brushless motor 20 flowing through the transistor 21b. A display circuit 26 displays the state of the DC brushless motor 20. 28
Reference numeral b is a microcomputer which outputs a signal to the transistor 21b, outputs a signal to the display circuit 26 when the DC brushless motor 20 is locked, displays the signal and stops the load circuit 27. Control. 29
Is an AC power supply. Reference numeral 30 denotes a DC motor power source, which receives the AC power source 29 as an input and is used as a DC brushless motor 2.
Generate 0 DC power supply. Reference numeral 31 is a power supply for a microcomputer, which is input with the power supply of the DC motor power supply 30 to generate a 5V power supply.

The operation of the above structure will be described with reference to the voltage waveforms at the respective portions shown in FIGS. First, the micro-computer 28b turns on the transistor 21b by turning on the transistor 21b by turning on one side of the resistor 21a and the output part connected to the base of the transistor 21b from the ground level to rotate the DC brushless motor 20. Let At the same time, the micro computer 28b is replaced by the micro computer 28b.
The load circuit 27 according to the program stored in the storage unit of
To work. When the DC brushless motor 20 is rotating normally, the waveform as shown in FIG. 7A is input to the non-inverting terminal of the comparator 24a.

Further, as shown in FIG. 7A, a reference voltage obtained by dividing the power supply 31 for the microcomputer by the resistors 23a and 23b is input to the inverting terminal of the comparator 24a. Therefore, at the output terminal of the comparator 24a, as shown in FIG. 7 (b), a pulse corresponding to the rotation speed and the excitation method of the DC brushless motor 20 of high level and ground level of about 5V is generated. At time t1, the output terminal of the comparator 24a becomes the ground level, so that the electric charge of the electrolytic capacitor 25c is transferred to the resistor 25b.
To rapidly discharge through. Comparing at time t2
Since the output terminal of the battery 24a is in the open state, the electrolytic capacitor 25c is slowly charged through the resistor 25a. Here, if the constants of the resistor 25a and the electrolytic capacitor 25c are set sufficiently larger than the period when the output terminal of the comparator 24a becomes the ground level, and the resistor 25b is made sufficiently small, the microcomputer 2
The signal input to 8b holds the ground level as shown in FIG. 7 (c). The microcomputer 28b that receives this signal determines that the DC brushless motor 20 is rotating normally, and causes the load circuit 27 to continue to operate according to the program stored in the storage unit.

When the DC brushless motor 20 is locked, the current flowing through the transistor 21b for driving the DC brushless motor 20 becomes large and a continuous DC current is generated, so that the comparator 24a is not connected. A voltage as shown in FIG. 7D is input to the inverting terminal. Further, the inverting terminal of the comparator 24a is provided with a resistor 23a and a resistor 23b as shown in FIG.
A reference voltage obtained by dividing the power source 31 for the power supply is input, and the voltage of the output terminal of the comparator 24a and the terminal of the electrolytic capacitor 25c becomes a high level of almost 5V as shown in FIG. 7 (e). There is. When this signal is input to the micro computer 28b, the micro computer 28b
Determines that the DC brushless motor 20 is locked, displays this on the display circuit 26, and stops the operation of the load circuit 27. In this case, the high level of 5V may be held, or the voltage level may be held and each signal level may be determined according to the state of the DC brushless motor 20. Further, the control of the load circuit 27 may be performed not only to stop the operation immediately but also to stop the operation after a lapse of a predetermined time so that the electronic circuit is not destroyed.

As described above, the present invention is a DC brushless motor.
The current of the DC brushless motor 20 which flows through the transistor 21b for driving the DC brushless motor 20 is detected, the magnitude thereof is compared with the reference voltage, and the voltage level of the compared output is held so that the DC brushless motor 20 Since the locked state is detected, it is possible to eliminate the connection line by using one substrate, and the structure is simple and the material cost and work cost can be reduced. Further, since the set value of the reference voltage setting means 23 can be set to approximately the middle of the voltage level of the microcomputer power supply 31, the locked state of the DC brushless motor 20 can be detected more reliably.

[0033]

As described above, the present invention compares the output signal of the current detecting means for detecting the current of the DC brushless motor flowing in the motor driving means with the output signal of the reference voltage setting means for setting the reference voltage. The output of the comparison means detects the locked state of the DC brushless motor flowing to the motor drive means for driving the DC brushless motor, so that it is possible to eliminate the connection line by using one board. Since the structure is simple and the material cost and work cost can be reduced, and one kind of signal is output when the DC brushless motor is locked, a program for processing by the microcomputer is required. Can be easy.

Further, by providing the voltage level holding means for holding the output level of the comparing means for a predetermined time, the set value of the reference voltage setting means can be set to about the middle of the maximum output signal level of the current detecting means. As a result, the locked state of the DC brushless motor can be detected more reliably.

Further, by providing the display circuit, the user can easily understand the locked state of the DC brushless motor.

[Brief description of drawings]

FIG. 1 is a main block diagram of a control circuit of a DC brushless motor according to a first embodiment of the present invention.

FIG. 2 is a control circuit diagram of the DC brushless motor of the same.

FIG. 3 is a diagram showing voltage waveforms at various parts of the control circuit of the DC brushless motor.

FIG. 4 is a diagram showing voltage waveforms of other parts of the control circuit of the DC brushless motor.

FIG. 5 is a main block diagram of a DC brushless motor according to a second embodiment of the present invention.

FIG. 6 is a control circuit diagram of the same DC brushless motor.

FIG. 7 is a diagram showing voltage waveforms at various parts of the control circuit of the DC brushless motor.

FIG. 8 is a main block diagram of a control circuit of a conventional DC brushless motor.

FIG. 9 is a control circuit diagram of the same DC brushless motor.

FIG. 10 is a diagram showing voltage waveforms at various parts of the control circuit of the DC brushless motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC brushless motor 2 Motor drive means 3 Current detection means 4 Reference voltage setting means 5 Comparison means 6 Display circuit 7 Load circuit 8 Control means

Claims (3)

[Claims] 1. A DC brushless motor with a fan, a motor drive means for driving the DC brushless motor, and a current of the DC brushless motor flowing through the motor drive means. Current detecting means, reference voltage setting means for setting a reference voltage, comparing means for comparing two output signals of the current detecting means and the output signal of the reference voltage setting means, and the motor drive And a control means for controlling the means, the control means detecting the locked state of the DC brushless motor by the output signal of the comparing means to control the load circuit, and the control circuit of the DC brushless motor. 2. A DC brushless motor with a fan, a motor driving means for driving the DC brushless motor, and a current of the DC brushless motor flowing through the motor driving means. Current detecting means, reference voltage setting means for setting a reference voltage, comparing means for comparing two output signals of the output signal of the current detecting means and the output signal of the reference voltage setting means, and the output of the comparing means. A voltage level holding means for holding the level for a predetermined time and a control means for controlling the motor driving means are provided, and the control means detects the lock state of the DC brushless motor by an output signal of the voltage level holding means. A control circuit for a DC brushless motor that controls the load circuit. 3. A control circuit for a DC brushless motor according to claim 1, further comprising a display circuit for displaying the state of the DC brushless motor.