JPH11252980A - Motor drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the rotational frequency of a motor at a low speed with high accuracy. SOLUTION: When the power consumption of a personal computer is low, a low-level off-control signal is outputted to a control signal terminal 23, and first and fourth transistor 25, 35 are turned on by the divided voltage of fourth and fifth resistors 27, 28. If the voltage of a base (B) of the second transistor 26 is lower than the voltage of a base (A) of the first transistor 25, the collector current of the fourth transistor 35 is increased, so that the voltage of the base (B) of the transistor 26 increases. If the voltage of the base (B) of the second transistor 26 is higher than the voltage of the base (A) of the first transistor 25, the collector current of the fourth transistor 35 is decreased, so that the voltage of the base (B) of the transistor 26 drops. The voltage of the base (B) of the second transistor 26 is thus controlled to become roughly equal to the voltage on the base (A) of the first transistor 25, so that a low voltage is applied between both of connection terminals 39, 40 of a motor 38 and a motor 7 can be rotated at a low speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driving device for controlling the speed of a motor such as a fan motor at a high speed and a low speed.

[0002]

2. Description of the Related Art A personal computer (hereinafter referred to as a personal computer) is usually provided with a fan for cooling heat generated when the personal computer is used. Recently, there has been a demand for such a fan for cooling the personal computer to reduce noise. Because of the increase, it has been considered to control the rotation speed of the fan motor by a control signal from a personal computer. As a motor driving device based on the control of a personal computer, a device having a configuration as shown in FIG. 3 has been conventionally proposed.

In FIG. 3, 1 is a + 5V power supply terminal, 2
Is a ground terminal, 3 is a control signal terminal of a personal computer which outputs a high-level ON control signal when the power consumption of the personal computer is large, and a low-level OFF control signal when the power consumption is small. 4 is a control signal output terminal of the base and the emitter. An NPN transistor 5 connected to the ground terminal 2 and a PNP transistor 5 connected to the ground terminal 2; an emitter connected to the power supply terminal 1;
The base is connected to the collector of the NPN transistor 4 via the current limiting first resistor 6, and when the NPN transistor 4 is turned on by a high-level ON control signal, the PNP transistor 5 is turned on. The collector of the PNP transistor 5 and the ground terminal The power supply voltage is applied to the motor coil of the motor 7 to which both the connection terminals 8 and 9 are connected.

Further, in FIG. 3, reference numerals 11 and 12 denote second and third resistors for voltage division provided in series between the power supply terminal 1 and the ground terminal 2, and 13 denotes a collector connected to the power supply terminal 1 and a base connected thereto. An NPN transistor connected to a connection point P between the second and third resistors 11 and 12 is a backflow prevention diode, and the anode and the cathode are NPN transistors 1
3 and one connection terminal 8 of the motor 7.

When the power consumption of the personal computer is large, a high-level ON control signal is output to the control signal terminal 3 as described above. The transistor 4 turns on. When the NPN transistor 4 is turned on, the PNP transistor 5 is turned on, a high voltage substantially equal to the +5 V power supply voltage is applied between the connection terminals 8 and 9 of the motor 7, the motor 7 rotates at high speed, and the fan is mounted on the personal computer. A cooling effect is exhibited.

A voltage equal to the potential difference between the connection point P and one connection terminal 8 of the motor 7 is applied to the base of the NPN transistor 13. In this case, the potential of one connection terminal 8 of the motor 7 is changed to the connection point P Therefore, the NPN transistor 13 does not turn on.

On the other hand, when the power consumption of the personal computer is small, the low-level off control signal is output to the control signal terminal 3 as described above, so that the NPN transistor 4 does not turn on and the PNP transistor 5 also turns on. Never. On the other hand, the NPN transistor 13 is turned on by a positive bias due to a potential difference between the connection point P and one connection terminal 8 of the motor 7 at the base of the NPN transistor 13, and the connection point P is grounded by turning on the NPN transistor 13. The low voltage obtained by subtracting the voltage drop between the base and the emitter of the NPN transistor 13 and the forward voltage drop of the diode 14 from the voltage between the terminal 2 and the motor 7
, The motor 7 rotates at a low speed, and the cooling effect of the personal computer by the fan is lower than when the power consumption is large.

[0008]

In order to meet the demand for a quieter fan motor for cooling a personal computer, it is important to keep the motor rotation speed accurately when the power consumption of the personal computer is small, that is, at a low speed. Becomes

However, in the case of the conventional driving device shown in FIG. 3, when the power consumption of the personal computer is small, the NPN is calculated from the voltage between the connection point P and the ground terminal 2 as described above.
A low voltage obtained by subtracting the voltage drop between the base and the emitter of the transistor 13 and the forward voltage drop of the diode 14 is applied to the motor 7, and these voltage drops are easily affected by variations in element characteristics and temperature changes. However, there is a problem that the applied voltage of the motor 7 at the time of low speed varies, and the motor rotation speed at the time of low speed rotation cannot be accurately maintained.

An object of the present invention is to make it possible to accurately maintain a constant motor rotation speed at a low speed.

[0011]

In order to solve the above-mentioned problems, the present invention provides a first switching which is turned on and off by input of an on control signal and an off control signal from a control signal output means to a control terminal, respectively. A second switching device which is provided in a flow path of a current from a power supply terminal to a motor coil and which is turned on by turning on the first switching element to close the flow path and supply a power supply voltage to the motor coil; An element, which operates by turning off the first switching element to turn on the second switching element, and controls a current flowing through the second switching element to supply a voltage supplied to the motor coil to the power supply voltage. Constant voltage supply means for controlling the voltage to a lower constant voltage.

According to this configuration, when an ON control signal is input from the control signal output means to the control terminal of the first switching element, the first switching element is turned on and the second switching element is turned on. Then, when the second switching element is turned on, the flow path of the current from the power supply terminal to the motor coil is closed, and the power supply voltage is supplied to the motor coil to rotate the motor at high speed.

When an off control signal is input from the control signal output means to the control terminal of the first switching element,
While the first switching element is turned off, the constant voltage supply means operates to turn on the second switching element. At this time, the current flowing through the second switching element is controlled by the constant voltage supply means, and the voltage supplied to the motor coil is controlled to a constant voltage lower than the power supply voltage, whereby the motor rotates at a low speed.

Therefore, by the operation of the constant voltage supply means and the second switching element, the voltage applied to the motor at the time of low speed is kept constant without being affected by the variation in element characteristics and the temperature change as in the prior art. The motor rotation speed at the time is accurately maintained at a constant value.

Here, the constant voltage supply means may be any as long as it can supply a constant voltage lower than a high voltage such as a power supply voltage to the motor coil without being affected by variations in element characteristics or temperature changes.

Also, the present invention is characterized in that the constant voltage supply means comprises two voltage dividing resistors which are provided in series between the power supply terminal and the ground and divides a power supply voltage, and a pair of transistors. The other input terminal is connected to the connection point of the two voltage dividing resistors and the motor coil, and one output terminal is connected or grounded to the power supply terminal via a current limiting resistor and controls the second switching element. A differential amplifier circuit connected to the terminal and the other output terminal connected to or grounded to the power supply terminal, wherein the differential amplifier circuit controls a signal to a control terminal of the second switching element. The second input terminal so that the voltage of the other input terminal is equal to the divided voltage of the two voltage dividing resistors.
And a constant voltage lower than the power supply voltage and equal to the divided voltage is supplied to the motor coil.

In this case, if there is a difference between the voltages of the two input terminals of the differential amplifier circuit, a voltage corresponding to the difference is generated between the two output terminals, whereby a signal to the control terminal of the second switching element is generated. The controlled current flowing through the second switching element is controlled, and the voltage of the other input terminal connected to the motor coil is controlled to be equal to the voltage of one input terminal connected to the connection point between the two voltage-dividing resistors. .

In this manner, the voltage at the other input terminal of the differential amplifier circuit becomes equal to the divided voltage obtained by dividing the two voltage-dividing resistors. A constant voltage lower than a high voltage such as a power supply voltage is supplied without receiving.

Incidentally, the constant voltage supply means may be constituted by an operational amplifier or the like in addition to the one constituted by the two voltage dividing resistors and the differential amplifier circuit as described above.

Further, according to the present invention, there are provided two voltage-dividing resistors which are provided in series between a power supply terminal and the ground to divide a power supply voltage, and a first and a second transistor, and one end of the first transistor is provided. One end of a second transistor is connected to the power supply terminal via a current limiting resistor, one end of the second transistor is connected to the power supply terminal, the base of the first transistor is connected to a connection point of the two voltage dividing resistors, and the other end of the two transistors is grounded. And a differential amplifier circuit having one end connected to the first
A third transistor connected to one end of the transistor, the other end of which is grounded, and a base to which an on-control signal and an off-control signal are input from a control signal output means; and a third transistor provided between the power supply terminal and the base of the second transistor. A fourth transistor having a base connected to one end of the first transistor; and a motor coil provided between the base of the second transistor and ground.

According to such a configuration, when the base voltage of the second transistor is lower than the base voltage of the first transistor, the collector current of the first transistor increases, and the base current of the fourth transistor increases. The collector current of the four transistors also increases, and the current flowing through the motor coil via the fourth transistor increases,
The base voltage of the second transistor increases.

On the other hand, when the base voltage of the second transistor is higher than the base voltage of the first transistor, the collector current of the first transistor decreases, the base current of the fourth transistor decreases, and the collector current of the fourth transistor also decreases. As the current decreases, the current flowing through the motor coil via the fourth transistor decreases, and the base voltage of the second transistor decreases.

In this way, the base voltage of the second transistor is controlled so as to be equal to the divided voltage by the two voltage dividing resistors, which is the base voltage of the first transistor. A constant voltage lower than a high voltage such as a power supply voltage is supplied without being affected.

In this case, the first and second transistors are N
Although it is preferable to use a PN type, it is needless to say that a PNP type may be used. And the fourth transistor is
If the first and second transistors are of the NPN type, they are of the PNP type, and if the first and second transistors are of the PNP type, they are of the NPN type.
It just needs to be a mold. Further, the first to fourth transistors may be field effect transistors.

Further, in the present invention, the control signal output means comprises an electronic device which outputs the ON control signal when the power consumption is large and outputs the OFF control signal when the power consumption is small.

In this way, the motor speed can be controlled to be high and low according to the high and low power consumption of the electronic device such as a personal computer, and particularly, the supply to the motor when the motor is running at low speed. Since the voltage can be maintained constant without being affected by variations in element characteristics and temperature changes, it is very effective in reducing the noise of the motor.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described with reference to FIG.

In FIG. 1, 21 is a + 5V power supply terminal,
22 is a ground terminal, 23 is a control of a personal computer as a control signal output means for outputting a high-level ON control signal when the power consumption of a personal computer (not shown) is large and a low-level OFF control signal when the power consumption is small. Signal terminal,
Reference numeral 24 denotes a differential amplifier circuit, which includes first and second NPN transistors 25 and 26. Here, the bases A and B of the first and second transistors 25 and 26 correspond to both input terminals of the differential amplifier circuit 24, and the collectors C and D of the first and second transistors 25 and 26 are differential. It corresponds to both output terminals of the amplifier circuit 24.

The first transistor 25 is connected to the connection point of the fourth and fifth resistors 27 and 28 which are provided in series between the power supply terminal 21 and the ground terminal 22 and divide the power supply voltage of +5 V. Is connected, the collector C of the first transistor 25 is connected to the power supply terminal 21 via the sixth current limiting resistor 29, and the collector D of the second transistor 26 is connected to the power supply terminal 21. The emitters of the second transistors 25 and 26 are both connected to the ground terminal 22 via a current limiting seventh resistor 30.

The fourth and fifth resistors 27 and 28 and the differential amplifier circuit 24 constitute a constant voltage supply means 31.

Further, in FIG. 1, reference numeral 33 denotes a third transistor whose base and emitter are connected to the control signal terminal 23 and the ground terminal 22, respectively, and whose collector is connected to the collector C of the first transistor 25 via an eighth resistor 34 for current limiting. The third switching transistor of the NPN type, which is the first switching element, is the second transistor of the second type.
, A PNP-type fourth transistor which is a switching element having an emitter, a base, and a collector, each having a power supply terminal 21, a collector C of the first transistor 25, and a second
It is connected to the base B of the transistor 26.

In FIG. 1, reference numeral 37 denotes a capacitor for preventing oscillation connected between the base and collector of the fourth transistor 35, and reference numeral 38 denotes a fan motor, and both connection terminals 39 and 40 at both ends of the motor coil. Is the second
It is connected to the base B of the transistor 26 and the ground terminal 22.

Next, the operation will be described.

When the power consumption of the personal computer is large, a high-level ON control signal is output to the control signal terminal 23 of the personal computer, so that the high-level ON control signal is input to the base of the third transistor 33. The third transistor 33 turns on. When the third transistor 33 is turned on, the fourth transistor 35 is turned on, and the voltage obtained by subtracting the voltage drop between the emitter and the collector of the on-state fourth transistor 35 from the power supply voltage between the connection terminals 39 and 40 of the motor 38. When the voltage is applied, the motor 38 rotates at high speed, and the fan exerts a high cooling effect on the personal computer.

At this time, the fourth transistor 3 in the ON state
Since the voltage drop between the emitter and the collector of the motor 5 is very small, a voltage substantially equal to the power supply voltage of +5 V is applied between the connection terminals 39 and 40 of the motor 38. Further, in the differential amplifier circuit 24, the base B of the second transistor 26 is substantially equal to the power supply voltage, so that the first transistor 25
Becomes higher than the voltage of the base A of the first transistor 2
5, the collector current becomes zero, and the differential amplifier circuit 24 does not operate.

On the other hand, when the power consumption of the personal computer is small, a low-level off control signal is output to the control signal terminal 23 of the personal computer, so that the third transistor 33 does not turn on and the fourth and fifth resistors 27 are not turned on. , 28 are applied to the base A of the first transistor 25, the first transistor 25 is turned on, the collector current flows, the differential amplifier circuit 24 operates, and the first transistor 2
By turning on 5, the fourth transistor 35 is turned on.

When the voltage of the base B of the second transistor 26 is lower than the voltage of the base A of the first transistor 25 during the operation of the differential amplifier circuit 24,
This acts to increase the collector current of the first transistor 25, thereby increasing the base current of the fourth transistor 35, increasing the collector current of the fourth transistor 35, and increasing the voltage of the base B of the second transistor 26 to the second level. The voltage at the base B of the second transistor 26 rises to be equal to the voltage at the base A of one transistor 25.

Conversely, when the voltage at the base B of the second transistor 26 is higher than the voltage at the base A of the first transistor 25, the collector current of the first transistor 25 acts to decrease, and 35, the collector current of the fourth transistor 35 decreases, and the base B of the second transistor 26 becomes equal to the voltage of the base A of the first transistor 25. Voltage decreases.

As described above, the voltage of the base B of the second transistor 26 is applied to the differential amplifier circuit 24 and the fourth transistor 35.
Is controlled to be substantially equal to the voltage of the base A of the first transistor 25, and the two connection terminals 39 of the motor 38,
A voltage lower than that when the power consumption of the personal computer is large is applied between 40 and the motor 38 rotates at low speed.

At this time, both connection terminals 39 of the motor 38,
A power supply voltage of +5 V is applied between the fourth and fifth resistors 27 and
A low voltage substantially equal to the divided voltage divided by 8 is applied. Generally, the resistance value of the resistor is higher in accuracy than the transistor and the diode and is less affected by the temperature. Voltage is very stable. Further, by adjusting the resistance values of the fourth and fifth resistors 27 and 28, the rotation speed of the motor 38 at low speed can be appropriately selected.

Therefore, according to the first embodiment, the motor speed can be controlled to be high and low according to the high and low power consumption of the personal computer, respectively. Circuit 24 and fourth transistor 3
5, the voltage of the base B of the second transistor 26 is the voltage of the base A of the first transistor 25.
Since the voltage is controlled so as to be equal to the divided voltage of the resistors 27 and 28, it is possible to supply the motor 38 with a constant low voltage which is not affected by variations in element characteristics and temperature changes. The rotation speed can be accurately maintained.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. In FIG.
1 denote the same or corresponding elements, and different points from FIG. 1 will be mainly described below.

This embodiment is an example in which a two-phase fan motor is driven. As shown in FIG. 2, a position detecting means 42 comprising a Hall element for detecting a rotational angle position of a rotor magnet and an eighth resistor are provided. 43 is a power supply terminal 21;
It is provided in series between a connection terminal 40 connected to the ground terminal 22. Switching means 46 for alternately switching the energization to the two-phase motor coils 44 and 45 of the fan motor in accordance with the rotational angle position of the rotor magnet detected by the position detecting means 42 includes a position detecting means 42 and an eighth resistor. 43 are connected in parallel to the series circuit.

At this time, a voltage substantially equal to the power supply voltage is supplied to the position detecting means 42 and the switching means 46, and a voltage between the connection terminals 39 and 40 is supplied to the motor coils 44 and 45. Have been. Therefore, a high voltage substantially equal to the power supply voltage appearing between the connection terminals 39 and 40 according to the power consumption of the personal computer, or the fourth and fifth resistors 27 and
A low voltage equal to the divided voltage by 28 is provided.

Therefore, according to the second embodiment, the same effects as in the first embodiment can be obtained.

In each of the above embodiments, the case where the constant voltage supply means 31 is constituted by the fourth and fifth resistors 27 and 28 and the differential amplifier circuit 24 has been described. In this case, the same effects as those of the above embodiment can be obtained. In short, the constant voltage supply means may be any unit that can supply a constant voltage lower than a high voltage such as a power supply voltage to the motor coil without being affected by variations in element characteristics or temperature changes.

In each of the above embodiments, the case where the control signal output means is a personal computer, which is an electronic device, has been described. However, the control signal output means is not limited to a personal computer. Control signal,
It is desirable that the electronic device output an off control signal when it is small.

Further, in each of the above embodiments, the first and second transistors 25 and 26 constituting the differential amplifier circuit 24 are provided.
Has been described as an NPN type, it is needless to say that both of the transistors 25 and 26 may be formed of a PNP type.
Needless to say, the transistors 3 and 35 may be constituted by field effect transistors. However, the first and second transistors 2
When the PNP transistors 5 and 26 are used, the fourth transistor 35 may be an NPN transistor.

The present invention is not limited to the above embodiments, and various changes other than those described above can be made without departing from the spirit of the present invention.

[0050]

As described above, according to the first aspect of the present invention, the voltage applied to the motor at a low speed is controlled to a constant voltage lower than the power supply voltage by the constant voltage supply means and the second switching element. As a result, the supply voltage to the motor at low speeds is not affected by variations in element characteristics or temperature changes, as in the past, and the motor speed at low speeds can be accurately maintained at a constant value, and noise is reduced. It is possible to provide a motor having good characteristics.

According to the second aspect of the present invention, when the off control signal is output from the control signal output means,
The voltage of the other input terminal of the differential amplifier circuit is controlled to be equal to the divided voltage by both voltage dividing resistors, and the resistance value is not affected by temperature changes. A low constant voltage can be supplied stably.

According to the third aspect of the present invention, when the off-control signal is output from the control signal output means,
Since the base voltage of the second transistor is controlled so as to be equal to the divided voltage by the two voltage-dividing resistors, which is the base voltage of the first transistor, when the motor rotates at a low speed, variations in element characteristics and temperature changes in the motor coil occur. A low voltage that is not affected can be supplied stably.

According to the fourth aspect of the present invention, when the power consumption of an electronic device such as a personal computer is small, the voltage supplied to the motor is kept constant without being affected by variations in element characteristics or changes in temperature. Since it can be maintained, it is very effective in reducing the noise of the motor.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a first embodiment of the present invention.

FIG. 2 is a connection diagram of a second embodiment of the present invention.

FIG. 3 is a connection diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 21 power supply terminal 22 ground terminal 23 control signal output terminal 24 differential amplifier circuit 25, 26 first and second transistors 33 third transistor (first switching element) 35 fourth transistor (second switching element) 38 fan motor 44, 45 Motor coil

Claims (4)

[Claims] 1. A first switching element which is turned on and off by input of an on control signal and an off control signal from a control signal output means to a control terminal, respectively, and is provided in a flow path of a current from a power terminal to a motor coil. A second switching element that is turned on when the first switching element is turned on to close the communication path and supplies a power supply voltage to the motor coil; and a second switching element that is operated by turning off the first switching element. Constant voltage supply means for turning on the second switching element and controlling the current flowing through the second switching element to control the voltage supplied to the motor coil to a constant voltage lower than the power supply voltage. A motor driving device characterized by the above-mentioned. 2. The power supply device according to claim 2, wherein the constant voltage supply means is provided in series between the power supply terminal and ground to divide the power supply voltage.
And a pair of transistors, one and the other input terminals are respectively connected to the connection point of the two voltage dividing resistors and the motor coil, and one output terminal is connected to the power supply terminal via a current limiting resistor. A differential amplifier circuit connected or grounded and connected to the control terminal of the second switching element and the other output terminal connected to or grounded to the power supply terminal; By controlling the signal to the control terminal of the switching element of, controlling the current flowing through the second switching element so that the voltage of the other input terminal is equal to the divided voltage by the two voltage dividing resistors, The motor driving device according to claim 1, wherein a constant voltage lower than the power supply voltage and equal to the divided voltage is supplied to the motor coil. 3. A voltage dividing resistor which is provided in series between a power supply terminal and a ground and divides a power supply voltage, and is constituted by first and second transistors, and one end of the first transistor has a current limiting resistor. The second transistor is connected to the power supply terminal via a second terminal, one end of the second transistor is connected to the power supply terminal, the base of the first transistor is connected to the connection point of the two voltage-dividing resistors, and the other end of the two transistors is grounded. A dynamic amplifier circuit, one end of which is connected to one end of the first transistor via another current limiting resistor, the other end of which is grounded, and an ON control signal and an OFF control signal from a control signal output means are input to a base; A transistor, a fourth transistor provided between the power supply terminal and the base of the second transistor, a base connected to one end of the first transistor, and a base of the second transistor. , Drive motor, characterized in that a motor coil provided between the ground. 4. The electronic device according to claim 1, wherein said control signal output means comprises an electronic device which outputs said ON control signal when power consumption is large and said OFF control signal when power consumption is small. A drive device for a motor according to any one of the above.