JP2001169589A - Motor drive device and electric equipment using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely prevent the temperature of a motor from increasing excessively. SOLUTION: A speed-indicating means 6 includes a heat sensitive resistance element 9 that is directly connected to a speed command means 8 for externally instructing the speed of a brushless DC motor 1, and a comparator 11 for outputting duty by comparing a voltage divided by the resistor 9 that is connected via the heat sensitive resistance element 9 with the output of a triangular wave generation circuit 12. Thus providing the motor-drive device that securely prevents the temperature of a motor 1 from increasing excessively by mistake by detecting the temperature of the motor 1 and limiting an application voltage without changing the frequency of the duty to be supplied to the motor 1 according to the actual temperature of the motor 1, and hence suppressing generation of noise and vibration with a simple configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device for a motor used as a blower fan drive source for a ventilation blower such as an air conditioner, a water heater, an air purifier, a ceiling fan, a range hood, and the like. And a ventilation blower using the same.

[0002]

2. Description of the Related Art In recent years, this type of motor driving device has realized high quality and high safety while realizing miniaturization, cost reduction, and space saving along with miniaturization and price reduction of mounted equipment. Is strongly required. In addition, with the high airtightness and high heat insulation of houses and the reduction of equipment installation space, there is a strong demand for ventilating blowers to be downsized, to suppress a rise in temperature of circuit components, to have high quality, and to have high safety. And
In such motors and drive circuits, the heat radiation space is limited, so if an abnormal condition such as motor lock or overload occurs, the motor temperature will rise excessively and damage to the motor windings and insulation failure will occur. In such cases, various electric circuits and circuit components built into the motor may be destroyed. In the worst case, there is a problem that the motor may be ignited due to an excessive temperature rise of the motor. A drive device for solving the problem has been proposed.

[0003] Conventionally, an example of this type of motor drive device shown in FIG. 8 has been known. Hereinafter, the configuration will be described with reference to the drawings.

[0004] As shown in FIG.
The C motor comprises a rotor having stator windings U, V, W and permanent magnets. Reference numeral 102 denotes a position detecting means composed of a Hall element or the like, which detects switching of the magnetic pole of the rotor and outputs magnetic pole signals Hu, Hv, Hw. 103 is a plurality of switching elements, 104 is a driving means, 105 is a switching element on / off signal generating means, 106 is a speed indicating means comprising a triangular wave generating circuit and a comparator, 109 is a lock detecting means, 107 is a DC power supply, The stator windings U, V, and W of the brushless DC motor 101 are connected to a plurality of switching elements 103 that supply drive signals Vu, Vv, and Vw for the stator windings U, V, and W, respectively. Have transistors Q1 and Q
2, Q3, Q4, Q5 and Q6 are provided, and diodes are connected in parallel to the transistors Q1 to Q6. The drive signal V of the stator windings U, V, W from the connection point of the transistors Q1 and Q4, Q2 and Q5, and Q3 and Q6.
u, Vv, and Vw are output, respectively. Transistor Q
1 to Q3 are connected to the positive electrode of DC power supply 107, and the emitters of transistors Q4 to Q6 are connected to DC power supply 10
7 is connected to the negative electrode. The position detecting means 102 is connected to the switching element on / off signal generating means 105, and the output of the switching element on / off signal generating means 105 is a control signal for turning on / off each of the transistors Q1 to Q6 of the plurality of switching elements 103. Is output to the drive unit 104 that outputs the data. The switching element on / off signal generating means 105 includes a speed instruction means 10.
6 and the lock detection means 109 are connected. The speed instructing means 106 compares the rotation number instructing means 108 for determining the rotation number of the brushless DC motor 101 with the triangular wave from the triangular wave generating circuit by a comparator, and switches the duty of the on-period according to the predetermined rotational speed. Output to the element on / off signal generation means 105, the lock detection means 109 detects the rotation speed of the brushless DC motor 101, and outputs drive signals Vu, V to each stator winding U, V, W.
Although v and Vw are supplied and current is flowing,
When the detected rotation speed is abnormally low or stopped, a lock signal is output.

In such a configuration, a brushless DC
When the motor 101 is locked, the lock detecting means 109
Outputs a lock signal, and the switching element on / off signal generating means 105 outputs an off signal based on the lock signal. On the other hand, when the brushless DC motor 101 is not locked, the energization ON signal of the brushless DC motor 101 is output. Thereby, the drive means 10
4 turns on / off each of the transistors Q1 to Q6 of the plurality of switching elements 103 according to a predetermined rotation speed when the brushless DC motor 101 is not locked.
Switching element on / off signal generating means 105
When the lock state of the brushless DC motor 101 is detected, the transistors Q1 to Q6 of the plurality of switching elements 103 are cut off via the drive unit 104,
The rotation of the brushless DC motor 101 has been stopped.

[0006]

According to such a conventional motor driving apparatus, the rotation speed of the brushless DC motor 101 is detected, and the processing is performed by judging from the state of energization of the stator winding. Therefore, depending on the structure and installation environment of the brushless DC motor 101, the brushless DC motor 10
When the lock of the brushless DC motor 1 is detected
In some cases, the temperature of the brushless DC motor 101 excessively increases by the time the brushless DC motor 101 stops, and the temperature of the stator windings may decrease. There were problems such as damage and poor insulation, and even breakdown of various electric circuits and electronic components of the built-in drive circuit.

Although a configuration using a temperature fuse or a temperature relay to prevent the above situation has been disclosed, a special configuration such as an external reset is required to restart the motor. There was a problem that.

Further, in order to limit the drive current supplied to the brushless DC motor when the temperature rises, a drive device that limits the drive current by a combination of a temperature-sensitive resistance element and a current limiting circuit (Japanese Patent Application Laid-Open No. H10-201280). ) Is disclosed, but there is a problem that noise is increased because the fundamental frequency of the duty always changes by limiting the drive current. Further, the current waveform is disturbed, so that the torque ripple and the rate of change in torque increase, and there is a problem that vibration and noise increase.

In a ventilation blower equipped with a motor driving device, the installation space of the device is narrow, and by installing the device in a place surrounded by a heat insulating material such as glass wool, the ambient temperature becomes high. In the case of the detection method, there is a problem that it is necessary to provide a margin for the rotation speed to be detected, and there is a possibility that the air volume required by the device may not be generated. Further, even when the configuration of Japanese Patent Application Laid-Open No. 10-201280 is applied, it is necessary to further reduce the value of the current limit, and there is a possibility that the air volume required by the device may not be obtained. There was a problem that noise increased.

SUMMARY OF THE INVENTION The present invention solves such a conventional problem. When the temperature of a motor, such as a lock, rises, the motor can be heated excessively without affecting noise and vibration with a simple configuration. It is an object of the present invention to provide a motor drive device capable of preventing such a problem and a ventilation blower equipped with the motor drive device.

[0011]

In order to achieve the above object, a motor driving device according to the present invention has a motor body having a plurality of stator windings and a rotor, and is connected to the stator windings. A plurality of switching elements for sequentially energizing in a predetermined direction and order; position detecting means for detecting a magnetic pole position of the rotor; speed instructing means for instructing the number of rotations of the motor; A switching element on / off signal generating means for outputting a signal necessary for rotating the rotor in a predetermined direction based on an output signal of the position detecting means, and a signal output from the switching element on / off generating means. Drive means for driving the plurality of switching elements, and the speed instruction means is serially connected to rotation speed instruction means for externally instructing the rotation speed of the motor. Continued, from normal temperature to the Curie temperature, has a substantially constant resistance value characteristic, and at a temperature equal to or higher than the Curie temperature, a temperature-sensitive resistance element having a relatively steep positive characteristic, at a predetermined cycle A triangular wave generating circuit that outputs a triangular wave; and a comparator that compares a voltage divided by a resistor connected in series via the temperature-sensitive resistance element and an output of the triangular wave generating circuit to output a duty. This is a configuration of a motor drive device.

According to the present invention, since the temperature of the motor can be detected and the duty, that is, the applied voltage can be limited according to the actual temperature of the motor without changing the frequency of the duty supplied to the motor. It is possible to obtain a motor drive device that can suppress generation of noise and vibration with a simple configuration and can reliably prevent the temperature of the motor from erroneously increasing excessively.

According to another aspect of the present invention, the speed indicating means includes a resistor to which the control power of the motor driving device is applied, a temperature-sensitive resistor connected in series with the resistor, and a resistor and the resistor. A transistor which is turned on / off based on the applied voltage, a triangular wave generating circuit which outputs a triangular wave at a predetermined cycle, an output of a rotational speed command means connected in series to a collector of the transistor, and a triangular wave generating circuit. This is a motor drive device having a comparator for comparing the output of the circuit and outputting a duty.

According to the present invention, the temperature of the motor can be detected and the duty, ie, the applied voltage can be turned on / off according to the actual temperature of the motor without changing the frequency of the duty supplied to the motor. Therefore, it is possible to obtain a motor drive device that can suppress generation of noise and vibration with a simple configuration and that can more reliably prevent the temperature of the motor from erroneously increasing excessively.

Another means is that the speed instructing means is connected in series to a rotational speed instructing means for externally instructing the number of rotations of the motor, and has a substantially constant resistance value characteristic from a normal temperature to a Curie temperature. At a temperature equal to or higher than the Curie temperature, a temperature-sensitive resistance element having a relatively steep positive characteristic, a triangular wave generation circuit that outputs a triangular wave at a predetermined cycle, and a series connection via the temperature-sensitive resistance element A motor driving device provided with a comparator for comparing a voltage divided by a resistor with an output of the triangular wave generation circuit and outputting a duty; or a speed instructing means, a resistor to which control power of the motor driving device is applied, A temperature-sensitive resistance element connected in series to a resistance, a transistor that is turned on / off based on a voltage divided by the resistance and the temperature-sensitive resistance element, and a triangular wave having a predetermined period. A motor drive device comprising: a triangular wave generating circuit for outputting a signal; and a comparator for comparing the output of a rotational speed command means connected in series to the collector side of the transistor with the output of the triangular wave generating circuit and outputting a duty. This is a configuration of an electric device equipped with a.

According to the present invention, it is possible to reliably satisfy the characteristics such as the air volume required by the equipment, to suppress the generation of noise and vibration with a simple structure, and to ensure that the temperature of the motor rises excessively by mistake. Thus, an electrical device that can be prevented is obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to achieve the above object, the present invention provides a motor body having a plurality of stator windings and a rotor, and a motor body connected to the stator windings, each having a predetermined direction and a predetermined order. A plurality of switching elements for sequentially energizing;
Position detecting means for detecting the magnetic pole position of the rotor, speed indicating means for indicating the number of rotations of the motor, and rotating the rotor in a fixed direction based on output signals from the speed indicating means and the position detecting means. Switching element on / off signal generating means for outputting a signal necessary for the switching, and driving means for driving the plurality of switching elements based on a signal output from the switching element on / off generating means, The instructing means is connected in series to a rotational speed instructing means for externally instructing the rotational speed of the motor, and has a substantially constant resistance value characteristic from a normal temperature to a Curie temperature. A temperature-sensitive resistance element having a steep positive characteristic, a triangular wave generating circuit that outputs a triangular wave at a predetermined cycle, and A motor drive device including a comparator that outputs a duty by comparing a voltage divided by a resistor connected to a column and an output of the triangular wave generation circuit, and detects a motor temperature. hand,
The duty, that is, the applied voltage is limited without changing the frequency of the duty supplied to the motor in accordance with the actual temperature of the motor.

The speed instructing means includes a resistor to which control power of the motor driving device is applied, a temperature-sensitive resistor connected in series to the resistor, and a voltage divided by the resistor and the temperature-sensitive resistor. A transistor which is turned on / off based on
A triangular wave generating circuit that outputs a triangular wave at a predetermined cycle, a comparator that compares the output of the rotational speed command means connected in series to the collector side of the transistor and the output of the triangular wave generating circuit, and outputs a duty. It is a configuration of a motor drive device having a motor, which detects the temperature of the motor and changes the duty, that is, the applied voltage without changing the frequency of the duty supplied to the motor according to the actual temperature of the motor. It has the effect of turning on and off.

The speed instructing means is connected in series to a rotational speed instructing means for externally instructing the rotational speed of the motor. The speed instructing means has a substantially constant resistance value characteristic from normal temperature to the Curie temperature, At temperature, the voltage is divided by a temperature-sensitive resistance element having a relatively steep positive characteristic, a triangular wave generation circuit that outputs a triangular wave at a predetermined cycle, and a resistor connected in series via the temperature-sensitive resistance element. The motor driving device provided with a comparator that compares the output voltage and the output of the triangular wave generation circuit to output a duty, or a speed instruction unit is connected in series with the resistor to which the control power of the motor driving device is applied and the resistor. A connected temperature-sensitive resistor, a transistor that is turned on / off based on a voltage divided by the resistor and the temperature-sensitive resistor, and outputs a triangular wave at a predetermined cycle. A motor drive device comprising: an angular wave generation circuit; and a comparator that compares the output of a rotation speed command means connected in series to the collector side of the transistor and the output of the triangular wave generation circuit and outputs a duty. This is a configuration of the installed electric equipment, and the limit value can be set strictly.
It has the effect of turning off.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) As shown in FIGS. 1 to 5, reference numeral 1 denotes a brushless DC motor main body mounted on a ventilating fan 1a of a ceiling embedded type or the like, and stator windings U, V, W and a permanent magnet. . Reference numeral 2 denotes a position detecting means composed of a Hall element or the like, which detects switching of the magnetic pole of the rotor. The plurality of switching elements 3 include transistors Q1,
Q2, Q3, Q4, Q5, and Q6 are connected to the stator windings U, V, and W. The positive electrode of the DC power supply 7
The negative electrodes are connected to the collectors of the transistors Q1 to Q3, and the negative electrodes are connected to the transistors Q4 to Q6. Reference numeral 9 denotes a temperature-sensitive resistance element which is an n-type valence control type semiconductor in which a rare earth element is added in a small amount to barium titanate, and is built in the housing of the brushless DC motor 1 whose temperature is to be detected. Reference numeral 6 denotes a temperature-sensitive resistance element 9 connected in series to a rotation speed command means 8 for externally commanding the rotation speed of the brushless DC motor 1, and a resistor 10 connected in series via the temperature-sensitive resistance element 9. The voltage V0 divided by the temperature-sensitive resistance element 9 and the resistor 10 by the speed indicating means is input to the input terminal of the comparator 11. Also, comparator 1
The other input terminal of 1 is connected to a triangular wave generating circuit 12 for outputting a triangular wave of a predetermined frequency, and the comparator 11 outputs a duty as a comparison result. The switching element on / off signal generating means 5 outputs a signal necessary for rotating the rotor in a fixed direction based on the signals from the position detecting means 2 and the speed indicating means 6.
The drive means 4 includes a plurality of switching elements 3 based on the output of the switching element on / off signal generation means 5.
To supply the current to the bases of Q1 to Q6.

The operation of the above configuration will be described.
FIG. 3 shows a temperature-resistance change ratio characteristic diagram of the temperature-sensitive resistance element 9 of this embodiment. As shown in FIG.
Up to 0 ° C, the resistance change ratio shows a gradual decreasing trend,
When the temperature exceeds 00 ° C., the resistance change ratio rapidly increases. The temperature at which the resistance change ratio rapidly increases is the Curie temperature.
When the brushless DC motor 1 is in an abnormal state such as a locked state or the like and the temperature of the stator winding rises and reaches the Curie temperature of the temperature-sensitive resistance element 9, the resistance value of the temperature-sensitive resistance element 9 rapidly increases, Voltage V divided by resistance element 9 and resistance 10
0 rapidly decreases and is input to the comparator 11. Then, the voltage V0 becomes smaller than the lower limit value VL of the triangular wave amplitude level of a predetermined frequency outputted from the triangular wave generating circuit 12 inputted to the other input terminal of the comparator 11, and the output of the comparator 11, that is, the speed indicating means. The duty, which is the output of No. 6, decreases or becomes zero, and the brushless DC motor 1 decelerates or stops.

In the first embodiment, the motor on which the motor driving device is mounted is the brushless DC motor 1. However, a switched reluctance motor, a synchronous reluctance motor, or an induction motor may be used, and there is no difference in operation and effect.

Although the position of the magnetic pole of the rotor is detected using a Hall element or the like, a method of detecting the position of the magnetic pole from an induced voltage induced in the stator winding of the motor may be used. Does not occur.

The temperature-sensitive resistance element 9 does not need to be built in the housing of the brushless DC motor 1, but may be fixed to the surface. If the temperature-sensitive resistance element 9 is installed at a position where the temperature is reliably changed according to the heat generated by the motor. , Does not cause a difference in the operation and effect.

The temperature-sensitive resistance element 9 uses an n-type valence control type semiconductor in which a rare earth element is added in a small amount to barium titanate, but a resistance element in which a polymer as an insulator and carbon as a conductor are blended. May be used, and there is no difference in the operation and effect.

The characteristics of the temperature-sensitive resistance element 9 to be used in the motor driving device may be appropriately selected from environmental conditions in which the motor is installed.

The same effect can be obtained by mounting the apparatus in an electric device such as an air purifier, an air conditioner, or an air conditioner instead of mounting the apparatus in a ventilation blower.

As described above, according to the motor driving apparatus of the first embodiment of the present invention, the temperature of the brushless DC motor 1 is detected and supplied to the brushless DC motor 1 according to the actual temperature of the brushless DC motor 1. Since the duty, that is, the applied voltage can be limited without changing the duty frequency, the current waveform is not disturbed, and the torque ripple and the rate of change in torque are suppressed with a simple configuration, thereby suppressing noise and vibration. Yes, brushless DC
It is possible to provide a motor drive device that can reliably prevent the temperature of the motor 1 from being excessively increased by mistake.

Further, in the ventilation blower equipped with the motor driving device according to the first embodiment of the present invention, the installation space of the equipment is narrow, and the ventilation blower can be installed in a place where the ambient temperature is high surrounded by heat insulating material such as glass wool. In addition, it is possible to reliably provide the air volume required by the equipment, and to provide a low-noise ventilation ventilation device.

(Embodiment 2) As shown in FIGS. 6 and 7, reference numeral 6 denotes a speed indicating means, and a resistor 10 to which a control power supply 13 is applied and a temperature-sensitive resistance element connected in series via the resistor 10. 9 is provided. A transistor 14 that is turned on and off based on a voltage V1 divided by the resistor 10 and the temperature-sensitive resistance element 9, and a rotation speed that externally commands the rotation speed of the brushless DC motor 1 applied to the collector of the transistor 14. The command means 8 is connected to an input terminal of the comparator 11. Also, the other input terminal of the comparator 11
A triangular wave generation circuit 12 that outputs a triangular wave of a predetermined frequency is connected, and the comparator 11 outputs a duty as a comparison result. The temperature-sensitive resistance element 9 is, for example, a brushless DC motor 1 whose temperature is to be detected.
Or fixed to the surface of the brushless DC motor 1. Other components are
This is the same as the first embodiment.

In the above configuration, when the brushless DC motor 1 enters an abnormal state such as a locked state and the temperature of the stator winding rises and reaches the Curie temperature of the temperature-sensitive resistance element 9,
The resistance value of the temperature-sensitive resistance element 9 rapidly increases, and the control power supply 13
The voltage V1 divided by the resistor 10 and the temperature-sensitive resistor 9 to which the voltage is applied rapidly increases, and the transistor 14 is turned on. At this time, the voltage output from the rotation speed command means 8 input to the comparator 11 becomes zero, and the triangular wave generation circuit 12 input to the other input terminal of the comparator 11
As a result, the output becomes lower than the lower limit value VL of the triangular wave amplitude level of the predetermined frequency, and the output of the comparator 11, that is, the duty as the output of the speed instruction means 6, becomes zero, and the brushless DC motor 1 stops.

Although the transistor 14 is used in the second embodiment, a comparator may be used, so that there is no difference in operation and effect.

As described above, according to the motor driving apparatus of the second embodiment of the present invention, the temperature of the brushless DC motor 1 is detected and supplied to the brushless DC motor 1 according to the actual temperature of the brushless DC motor 1. Since the duty, that is, the applied voltage can be turned on / off without changing the duty frequency, the generation of noise and vibration can be suppressed with a simple configuration, and the temperature of the brushless DC motor 1 is prevented from excessively rising erroneously. It is possible to provide a motor drive device that can more reliably prevent such a problem.

[0035]

As is apparent from the above embodiments, according to the present invention, the speed instructing means for instructing the rotation speed of the motor, and the rotor is controlled based on the output signals of the speed instructing means and the position detecting means. Switching element on / off signal generating means for outputting a signal necessary for rotating in a fixed direction; and driving means for driving a plurality of switching elements based on a signal output by the switching element on / off generating means. The speed instruction means is connected in series with a rotation speed instruction means for externally instructing the rotation speed of the motor, has a substantially constant resistance characteristic from normal temperature to the Curie temperature, and has a temperature equal to or higher than the Curie temperature. Then, a temperature-sensitive resistance element having a relatively steep positive characteristic, a triangular wave generating circuit that outputs a triangular wave at a predetermined cycle, and A comparator for comparing the voltage divided by the resistor connected to the output of the triangular wave generation circuit and outputting a duty to detect the temperature of the motor and respond to the actual temperature of the motor. hand,
The duty, that is, the applied voltage can be limited without changing the frequency of the duty supplied to the motor, noise and vibration can be suppressed with a simple configuration, and the temperature of the motor can be prevented from rising excessively by mistake. It is possible to provide a motor driving device capable of preventing the motor driving.

The speed instructing means includes a resistor to which control power of the motor driving device is applied, a temperature-sensitive resistor connected in series to the resistor, and a voltage divided by the resistor and the temperature-sensitive resistor. A transistor which is turned on / off based on
A triangular wave generating circuit that outputs a triangular wave at a predetermined cycle, a comparator that compares the output of the rotational speed command means connected in series to the collector side of the transistor and the output of the triangular wave generating circuit, and outputs a duty. With this arrangement, the temperature of the motor can be detected, and the duty, that is, the applied voltage can be turned on / off according to the actual temperature of the motor without changing the frequency of the duty supplied to the motor. With this configuration, an extremely safe motor drive device that can suppress increase in torque ripple and torque change rate, suppress generation of noise and vibration, and reliably prevent the motor temperature from excessively rising accidentally can be provided. it can.

The speed instructing means is connected in series to a rotational speed instructing means for externally instructing the number of revolutions of the motor. The speed instructing means has a substantially constant resistance value characteristic from normal temperature to the Curie temperature, At temperature, the voltage is divided by a temperature-sensitive resistance element having a relatively steep positive characteristic, a triangular wave generation circuit that outputs a triangular wave at a predetermined cycle, and a resistor connected in series via the temperature-sensitive resistance element. The motor driving device provided with a comparator that compares the output voltage and the output of the triangular wave generation circuit to output a duty, or a speed instruction unit is connected in series with the resistor to which the control power of the motor driving device is applied and the resistor. A connected temperature-sensitive resistor, a transistor that is turned on / off based on a voltage divided by the resistor and the temperature-sensitive resistor, and outputs a triangular wave at a predetermined cycle. A motor drive device comprising: an angular wave generation circuit; and a comparator that compares the output of a rotation speed command means connected in series to the collector side of the transistor and the output of the triangular wave generation circuit and outputs a duty. With the built-in, the applied voltage is limited or the applied voltage is turned on / off to prevent excessive temperature rise of the motor, so that the air volume required by the equipment can be satisfied satisfactorily and noise and vibration are suppressed with a simple configuration Thus, it is possible to provide an extremely safe and high-performance electric device capable of reliably preventing the temperature of the motor from being excessively increased by mistake.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a motor drive device of the present invention.

FIG. 2 is a detailed circuit configuration diagram of a speed instruction unit according to the first embodiment.

FIG. 3 is a diagram showing a temperature-resistance change ratio characteristic of a temperature-sensitive resistance element.

FIG. 4 is a diagram showing a relationship between a temperature characteristic of a voltage V0 and a duty.

FIG. 5 is a schematic diagram showing a state when a ventilation fan using the motor drive device of the present invention is installed.

FIG. 6 is a detailed circuit configuration diagram of a speed instruction unit according to the second embodiment.

FIG. 7 is a diagram showing a relationship between a temperature characteristic and a duty of the voltage V1.

FIG. 8 is a circuit configuration diagram of a conventional motor drive device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brushless DC motor 1a Ventilation fan 2 Position detection means 3 Plural switching elements 4 Drive means 5 Switching element ON / OFF signal generation means 6 Speed indication means 7 DC power supply 8 Speed command means 9 Temperature sensitive resistance element 10 Resistance 11 Comparator 12 Triangle wave Generator 13 Control power supply 14 Transistor

Claims (4)

[Claims] A motor body having a plurality of stator windings and a rotor; a plurality of switching elements connected to the stator windings for sequentially energizing in a predetermined direction and order, respectively; Position detecting means for detecting the magnetic pole position of the rotor, speed instructing means for instructing the number of rotations of the motor, and for rotating the rotor in a fixed direction based on output signals from the speed instructing means and the position detecting means. A switching element on / off signal generating means for outputting a necessary signal,
Drive means for driving the plurality of switching elements based on a signal output by the switching element on / off generation means, wherein the speed instruction means is a rotation speed instruction means for externally instructing the rotation speed of the motor. A series-connected, temperature-sensitive resistance element having a substantially constant resistance characteristic from normal temperature to the Curie temperature, and having a relatively steep positive characteristic at a temperature equal to or higher than the Curie temperature, is predetermined. A triangular wave generating circuit that outputs a triangular wave with a period, and a comparator that compares a voltage divided by a resistor connected in series via the temperature-sensitive resistance element with an output of the triangular wave generating circuit and outputs a duty. A motor drive device characterized by being provided. 2. The speed indicating means includes a resistor to which a control power of a motor driving device is applied, a temperature-sensitive resistor connected in series to the resistor, and a voltage divided by the resistor and the temperature-sensitive resistor. A transistor which is turned on / off based on a voltage, a triangular wave generating circuit which outputs a triangular wave at a predetermined cycle, an output of a rotation speed command means connected in series to a collector side of the transistor, and an output of the triangular wave generating circuit 2. A motor driving device according to claim 1, further comprising a comparator for comparing the values and outputting a duty. 3. An electric device comprising the motor drive device according to claim 1 mounted thereon. 4. The electric device according to claim 3, wherein the electric device is a ventilation device,
A ventilation blower characterized by being one of an air purifier, an air conditioner, and an air conditioner.