JP2002354870A - Brushless motor drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless motor drive capable of preventing a motor from being overheated with high response using a simple structure. SOLUTION: An output terminal is provided with an overheat protecting means 7 connected to a PWMDUTY command signal input terminal 16 of a 1-tip IC 6 in a brushless motor driving means. If the overheat protecting means 7 sets the input voltage of the PWMDUTY command signal input terminal 16 so as to lower or become zero, and so that the ON period of the switching device 5 is limited or turned off if the temperature of a switching device 5 of the 1-tip IC 6 exceeds a prescribed value. Thus, the switching device is restrained from being overheated, thereby attaining such high reliability that the drive is prevented from being destructed even under an overload condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor driving device provided with heating protection means and a brushless motor incorporating the same.

[0002]

2. Description of the Related Art Brushless motors are used in the field of home and commercial electric appliances such as air conditioners and air purifiers.

[0003] When an abnormal state such as lock or overload of the brushless motor occurs, the temperature of the brushless motor excessively rises, the windings of the brushless motor are damaged or insulation is poor, and various kinds of electrics built in the brushless motor are not included. Circuits and electronic circuits were sometimes destroyed. In the worst case, a fire may occur due to an excessive temperature rise of the brushless motor.

As a prior art for this measure, Japanese Patent Laid-Open Publication No.
FIG. 14 is a circuit diagram showing an electric configuration of a conventional motor driving device, and FIG. 15 is a block diagram showing a configuration of the driving device.

In FIG. 14, the voltage applied between the base and the emitter of the transistor Q2 is VBE2 = VCE1 + R2.times. (VCC-VCE1) / (R1 + R2) .multidot., Where R1 and R2 are R1 and R2, respectively. 1) Generally, the collector-emitter voltage VCE of a transistor has a positive temperature characteristic when the transistor is in a saturated state, and the base-emitter threshold voltage Vth has a negative temperature characteristic.

Therefore, when the temperature rises, the voltage VBE2 in the equation (1) increases, and the threshold voltage Vth2 of the transistor Q2 decreases. And the relation is VBE2 ≧
When the temperature becomes high enough to satisfy Vth2, the transistor Q2 turns on and the transistor Q8 turns off.
As a result, the current to the motor is cut off.

Therefore, corresponding to the actual temperature of the motor,
This is a configuration in which the drive current supplied to the motor can be limited.

[0008]

The driving device having such a configuration has the following problems.

The motor drive device must be a special one-chip IC in which components including a switch element, which is a heating element, are protected from overheating of the motor drive device in a monolithic manner. Is difficult to use when a motor drive device is composed of a one-chip IC or discrete semiconductor components that do not include a semiconductor chip. There is a need for a motor drive device that can provide effective protection.

[0010] In recent years, as motors have been downsized and inverter circuits have been downsized, heat sources have been concentrated, and the temperature has risen significantly when the motor is locked or overloaded, resulting in higher responsiveness and overheating. Sometimes, it is also required to quickly suppress or cut off the motor driving current to prevent the motor and the motor driving device from being damaged by overheating.

[0011] The present invention solves such a technical problem,
An object of the present invention is to provide a brushless motor driving device that can prevent overheating of a motor with a simple configuration and a high responsiveness.

[0012]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention uses a DC power supply as a power source, and a PWM forming unit in which a duty ratio is varied by a PWMDUTY command signal input from the outside. In a drive device for a brushless motor that supplies power to a brushless motor via a plurality of switch elements whose ratio of ON period / OFF period is variably controlled, an overheat protection unit is provided, and a power loss generated in the switch element is used. When the drive device of the brushless motor generates heat and reaches a predetermined temperature, the overheat protection means acts on the PWMDUTY command signal input terminal to reduce or reduce the voltage value of the signal input to the input terminal to zero. , The ON period of the switch element is limited.

Thus, a brushless motor driving apparatus which can prevent overheating of the brushless motor with a simple configuration and a high response can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention uses a DC power supply as a power source and externally inputs PWM.
PW whose DUTY ratio is varied by the DUTY command signal
In a brushless motor driving device for supplying power to a brushless motor via a plurality of switch elements whose ON period / OFF period ratio is variably controlled by the operation of the M forming unit, an overheat protection means is provided, When the driving device of the brushless motor generates heat due to the power loss generated in the above and reaches a predetermined temperature, the overheat protection means acts on the PWMDUTY command signal input terminal to generate a voltage of the signal input to the input terminal. The ON period of the switch element is limited or O
A drive device for a brushless motor characterized by performing FF. Even if the drive device for the brushless motor generates heat due to power loss generated in the switch element,
It has the effect of suppressing the temperature rise below a predetermined temperature.

According to a second aspect of the present invention, a voltage obtained by dividing the overheat protection means by a resistance from a reference voltage is input to one input terminal, and the other input terminal is grounded via a thermistor and a resistor. Is connected to a reference voltage via a resistor, and the output terminal is a PW of a brushless motor driving device.
2. The brushless motor driving device according to claim 1, wherein the brushless motor driving device is configured by a comparator connected to an MDUTY command signal input terminal. When a predetermined temperature is reached, the voltage at the other input terminal of the comparator becomes lower than the voltage at one input terminal, that is, the voltage divided from the reference voltage due to the decrease in the resistance value of the thermistor, The output changes from open to LOW and is input to the PWMDUTY command signal input terminal, turning the switch element ON and OFF
When the drive device of the brushless motor once exceeds the predetermined temperature and falls below the predetermined temperature, the output of the comparator is switched from LOW to open and the switch element is returned from OFF to ON again. Have.

According to a third aspect of the present invention, a voltage obtained by dividing a resistance from a reference voltage is inputted to one input terminal of the overheat protection means, and the other input terminal is grounded via a thermistor and a resistor. Is connected to a reference voltage via a resistor, and the output terminal is a PW of a brushless motor driving device.
2. The brushless motor driving device according to claim 1, wherein the brushless motor driving device is constituted by a hysteresis comparator connected to an MDUTY command signal input terminal. When it generates heat and reaches a predetermined temperature,
Due to the decrease in the resistance value of the thermistor, the voltage of the other input terminal of the comparator becomes smaller than the voltage of one input terminal, that is, the voltage divided from the reference voltage, and the output of the comparator changes from open to LOW and PWMD
It is input to the UTY command signal input terminal to turn on and off the switch element, and the driving device of the brushless motor that has once exceeded the predetermined temperature drops below the predetermined temperature and further drops to the second predetermined temperature. In this case, the output of the comparator is switched from LOW to open, and the switching element is returned from ON to ON again.

According to a fourth aspect of the present invention, the overheat protection means includes a transistor having a series resistor connected to the base and a resistor connected between the base and the emitter. The terminal is grounded via a PTC (positive characteristic) thermistor, connected to a reference voltage via a resistor, the emitter is grounded, and the collector is connected to a PWMDUTY command signal input terminal. 1. The driving device for a brushless motor according to item 1, wherein the driving device for the brushless motor generates heat due to power loss generated in a switch element.
When the temperature reaches a predetermined temperature, the resistance value of the PTC (positive characteristic) thermistor increases, and the voltage at the other end of the resistor connected in series to the base of the transistor increases. When a current is input to the base of the transistor and the transistor is turned on, the voltage at the PWMDUTY command signal input terminal to which the collector is connected is reduced, and the ON period of the switch element is limited.

According to a fifth aspect of the present invention, there is provided an overheat protection means, wherein a transistor having a series resistor connected to the base and a resistor connected between the base and the emitter is provided. The end is connected to a reference voltage via a thermistor, is grounded via a resistor, the emitter is also grounded, and the collector is a PWM.
2. A brushless motor driving device according to claim 1, wherein the driving device is connected to a duty command signal input terminal.
When the driving device of the brushless motor generates heat and reaches a predetermined temperature, the voltage at the other end of the resistor connected in series to the base of the transistor increases due to a decrease in the resistance value of the thermistor, thereby reducing the series resistance. A current is input to the base of the transistor, and the transistor is turned on. The voltage of the PWMDUTY command signal input terminal to which the collector is connected decreases, and the ON state of the switch element is reduced.
Has the effect of limiting the period.

According to a sixth aspect of the present invention, there is provided a brushless motor drive comprising an overheat protection means for limiting an ON period of a switch element when a voltage generated in a positive temperature coefficient thermistor reaches a predetermined value. The drive device of the brushless motor generates heat due to power loss generated in the switch element, and when the temperature reaches a predetermined temperature, the resistance value of the positive temperature coefficient thermistor increases.
When the voltage generated in the C (positive characteristic) thermistor reaches a predetermined value, the ON period of the switch element can be limited.

According to a seventh aspect of the present invention, there is provided a brushless motor having the brushless motor driving device according to any one of the first to sixth aspects incorporated therein. Has an action not to exceed a predetermined temperature even in the event of overload or the like.

According to an eighth aspect of the present invention, there is provided an air conditioner in which the brushless motor according to the seventh aspect is used for blowing air. Even when the motor is overloaded, the air conditioner does not exceed a predetermined temperature. It has the effect of improving the reliability and safety of the shocker and not deforming the casing of the thermoplastic resin.

According to a ninth aspect of the present invention, there is provided an air purifier provided with the brushless motor according to the seventh aspect for blowing air. It has the effect of improving the reliability and safety of the machine and not deforming the casing of the thermoplastic resin.

According to a tenth aspect of the present invention, there is provided a garbage disposer characterized in that the brushless motor according to the seventh aspect is used for blowing air. And has the effect of improving the reliability and safety of the garbage disposal machine and not deforming the thermoplastic resin housing.

[0024]

Next, specific examples of the present invention will be described.

(Embodiment 1) In FIG. 1, a one-chip IC 6 which is a driving device of a brushless motor includes switch elements 5a, 5b, 5c, 5d, and typified by IGBTs.
Inverter circuit 5 having a three-phase bridge configuration of 5e and 5f, regulator 10, PWM forming unit 4, overcurrent detection circuit 11, three-phase distribution circuit 12, gate drive circuit 13
Is connected to the output terminal of the inverter circuit 5 by connecting each phase winding of the brushless motor 1,
When the DC power supply 2, the control power supply 8, and the PWMDUTY command signal 3 are input, the one-chip IC 6 causes the one-chip IC 6 to switch the switch element 5 based on a signal from a rotor position detection sensor (not shown).
The switches a, 5b, 5c, 5d, 5e, and 5f are switch-controlled to supply power from the DC power supply 2 to the brushless motor 1.
The increase / decrease in power supply depends on the ON period of the switch element group and O
This is performed by PWM control that varies the ratio of the FF period (PWMDUTY ratio) within a certain period. The PWMDUTY ratio is determined by the PWM forming unit 4 based on a comparison result between the triangular wave of the triangular wave oscillator 17 and the voltage VSP of the PWMDUTY command signal input terminal 16, and specifically, PWMDU.
When the voltage VSP of the TY command signal input terminal 16 increases, the ON period increases, and when the VSP decreases, the ON period shortens. When VSP is 0, the ON state is maintained.

If the brushless motor 1 is overloaded for some reason and the rotation speed of the brushless motor 1 decreases, the current flowing through the brushless motor 1 increases. The current is supplied to the inverter circuit 5 of the one-chip IC 6.
Flows through each of the switch elements (5a to 5f), the one-chip IC 6 is overheated due to the increase in current and the loss of the switch elements (5a to 5f), and the temperature rises sharply. The overheat protection means 7 acts on the PWMDUTY command signal input terminal 16 immediately when the temperature of the one-chip IC 6 exceeds a predetermined value, reduces the input voltage VSP, and limits the ON period of the switch element to a short time or , VSP is set to 0 V, and there is no ON period, that is, OFF is maintained, and the current flowing through the switch element group is reduced or set to 0, so that the one-chip IC 6 can be prevented from overheating.

(Embodiment 2) In FIG. 2, the thermistor 26 as a component of the overheat protection means 7 is a one-chip IC 6
When the temperature of the one-chip IC 6 increases due to overheating, the resistance value of the thermistor 26 decreases. The third comparator 2
The non-inverting input terminal voltage of 1 also decreases. On the other hand, a constant voltage obtained by dividing the voltage VB of the first reference power supply output terminal by the first and second resistors 22 and 23 is input to the inverting input terminal. During normal operation, the voltage of the inverting input terminal is smaller than the voltage of the non-inverting input terminal, and the output of the third comparator is open (High impedance).
, The voltage at the non-inverting input terminal decreases significantly, and finally the relationship of the voltage at the inverting input terminal> the voltage at the non-inverting input terminal is reached, the output of the third comparator becomes 0 V, and the ON period of the switch element is 0. That is, the current becomes 0 and overheating of the one-chip IC 6 is prevented.

FIG. 10 shows a first resistor 22 and a second resistor 2.
3. The third resistor 24 is 15 kΩ and the fourth resistor 25 is 12
kΩ, the voltage VB of the first reference power supply output terminal is 7.5
V, when the temperature characteristic of the resistance of the thermistor 26 is (a), the temperature characteristic of the input voltage of the third comparator 21 is shown in (b).

As shown in FIG. 10, the temperature Ta = 100-1.
It can be seen that the magnitude relationship between the non-inverting input terminal voltage V + and the inverting input terminal voltage V− is inverted at 25 ° C. Generally, the upper limit of the guaranteed temperature of silicon semiconductor parts is 150 ° C.,
Since the upper limit of the operating temperature during normal operation is 80 to 100 ° C., extremely good characteristics are shown.

The time required for the temperature to be limited to a predetermined value is, for example, in the case of a motor having a built-in driving device of 140 VDC and a shaft output of 30 W, the motor is saturated in a locked state from the start of operation to a predetermined limit temperature. It takes only about 5 minutes to complete.

(Embodiment 3) In FIG. 3, the temperature characteristic of the input voltage V + to the non-inverting input terminal of the third comparator 21 is the same as that of the second embodiment. However, by providing the hysteresis unit 33, the input voltage V
During the normal operation in which the output of the third comparator 21 is High impedance, the operation is the same as that of the second embodiment, but at a high temperature, the third comparator 21
When the output is low, the operation in which the first transistor 28 conducts and the inverting input terminal voltage V- rises is different from the second embodiment.

FIG. 11 is a characteristic diagram showing an actual operation. (A) shows the time change of the temperature of the one-chip IC 6 at the time of overload, and (b) shows the third comparator 21.
11 (c) shows a voltage change at the non-inverting input terminal V + and the inverting input terminal V-, and FIG.

In FIG. 11, at time t1, the magnitude relationship between the non-inverting input terminal voltage V + and the inverting input terminal voltage V− = V− (1) changes from V +> V− to V + <V when the temperature of the one-chip IC 6 rises. −, The third comparator 21 switches from open to LOW, VSP = 0 V, the power supply to the brushless motor 1 stops, and the one-chip IC 6
Of the temperature decreases. At the same time, the inverted input terminal voltage V-
When the first transistor 28 conducts, V- becomes V-
(1) <V− (2) where V− = V− (2). 1
When the temperature of the chip IC 6 decreases, the thermistor 26
At time t2, V + <V− = V− (2)
Then, the third comparator 21 switches from LOW to open again, and the VSP becomes the High level of the PWMDUTY command signal input from the outside,
The power supply to the brushless motor 1 is restored. Thereafter, the same operation is repeated, and the temperature rise of the one-chip IC 6 is suppressed.

FIG. 12 shows a first resistor 22 and a second resistor 2.
3. The third resistor 24 is 15 kΩ and the fourth resistor 25 is 12
A characteristic diagram showing the input voltage temperature characteristics of the third comparator 21 when kΩ, the resistance value of the ninth resistor 27 is 44.2 kΩ, and the voltage VB of the first reference power supply output terminal is 7.5 V. And the inverted input voltage V− becomes V− (1) = 3.5
V, V− (2) = 4.3 V, and from the temperature characteristic value of the non-inverting input terminal voltage V +, the energization cutoff temperature T1 is 11
0 ° C., and the power return temperature T2 becomes 80 ° C.

The time required for the temperature to be limited to a predetermined value is, for example, in the case of a motor having a built-in driving device of 140 VDC and a shaft output of 30 W, the motor is saturated in a locked state from the start of operation to a predetermined limit temperature. It takes only 7 minutes to complete.

(Embodiment 4) In FIG. 4, a PTC (positive characteristic) thermistor 37 of the overheat protection means 7 is a one-chip IC.
When the temperature rises due to overheating of the one-chip IC 6, the resistance value of the PTC thermistor 37 increases, and the other end of the seventh resistor 35 connected in series to the base of the third transistor 32 Increases, the third transistor 32 starts conducting, the collector voltage of the third transistor 32, that is, the voltage VSP of the PWMDUTY command signal input terminal 16 decreases, and the switching element 5
The ON periods of a, 5b, 5c, 5d, 5e, and 5f are limited (short), the power supply to the brushless motor 1 is limited, and the temperature rise of the one-chip IC 6 is suppressed.

The time required for the temperature to be limited to a predetermined value is, for example, in the case of a motor with a built-in drive device of 140 VDC and a shaft output of 30 W, the motor is saturated in a locked state from the start of operation to a predetermined limit temperature. It takes only about 5 minutes to complete.

(Embodiment 5) Referring to FIG.
6 is thermally coupled to the one-chip IC 6,
When the temperature rises due to overheating of C6, the resistance value of the thermistor 26 decreases, and the voltage at the other end of the seventh resistor 35 connected in series to the base of the third transistor 32 increases. As in Example 4, when the third transistor 32 starts conducting, the collector voltage of the third transistor 32, that is, the PWMDUTY command signal input terminal 16
Of the switching elements 5a, 5b, 5
The ON periods of c, 5d, 5e, and 5f are limited (shortened), and the power supply to the brushless motor 1 is limited.
The temperature rise of the chip IC 6 is suppressed.

The time required for the temperature to be limited to a predetermined value is, for example, in the case of a motor having a built-in drive device of 140 V DC and a shaft output of 30 W, the motor is saturated in a locked state from the start of operation to a predetermined limit temperature. It takes only about 2.5 minutes to complete.

FIG. 13 shows a case where a thermistor having the resistance-temperature characteristic shown in FIG.
5, the resistance of the ninth resistor 38 is set to 10 kΩ,
kΩ, 820Ω, the resistance value of the series resistor 9 is 1 kΩ, the voltage VB of the first reference power supply output terminal is 7.5 V, and PWM is
FIG. 7 is a diagram showing temperature characteristics when the voltage of a DUTY command signal 3 is 6.1 V.

FIG. 13 shows that at Ta = 110 to 120 ° C.,
VSP is attenuating. This is because Ta = 110-1
At 20 ° C., the PWMDUTY ratio, ie, the O
It means that N period is limited.

(Embodiment 6) In FIG. 6, a PTC thermistor 37 thermally coupled to the one-chip IC 6 is provided in place of the current detection resistor, so that when the temperature rises due to overheating of the one-chip IC 6, the PTC When the resistance value of the thermistor 37 increases and the current is smaller than the current during normal operation, the overcurrent detection circuit 11 considers that the current limit value has been reached and determines that the switching elements 5a, 5b, 5c, 5
By acting to limit (short) the ON periods of d, 5e and 5f, the power supply to the brushless motor 1 is limited, and the temperature rise of the one-chip IC 6 is suppressed.

(Embodiment 7) In FIG. 7, on a printed circuit board 46, any one of Embodiments 1 to 6
The brushless motor drive device including the overheat protection means 7 is constituted, and the thermistor 2 provided on the printed circuit board 46 is provided.
6 or PTC thermistor 37 is made of a heat conductive material 47 such as silicon and is a one-chip IC 6 which is a heat source.
Are filled with each other, and are thermally coupled to each other. When the temperature rises due to overheating of the one-chip IC 6, the action of the overheat protection means 7 causes each switch element and the winding 50 in the one-chip IC 6 to move. , The thermal breakdown of the one-chip IC 6 and the burning of the winding 50 are eliminated, and the temperature rise of the brushless motor 1 itself is suppressed.

(Embodiment 8) The brushless motor 1 described in Embodiment 7 (FIG. 7) can be mounted on many home electric appliances or commercial electric appliances, and specific examples are shown in FIGS. 8 and 9. This will be described with reference to FIG.

In the air conditioner shown in FIG.
The brushless motor 1 rotates a cross flow fan 56 for the air conditioner indoor unit 54 and a propeller fan 57 for the air conditioner outdoor unit 55.

In the air cleaner 59 shown in FIG. 9, the brushless motor 1 rotates the sirocco fan 60.

The brushless motor 1 is shown in Embodiment 7
A brushless motor driving device including the overheat protection means 7 is built in. Even in the event of an abnormality such as overload, the heat generation of the brushless motor 1 is suppressed, and the air conditioner indoor unit 54,
The reliability and safety of the air conditioner outdoor unit 55 and the air purifier 59 are not impaired, and the resin casings of the air conditioner indoor unit 54 and the air purifier 59 around the brushless motor 1 are not thermally deformed.

The above-described electric equipment is an example. For example, in the case of a household or business garbage disposer, particularly a garbage disposer of a drying method using heat, the brushless motor may be heated even by external heating. Therefore, it is effective to use the brushless motor driving device of the present invention in order to ensure its reliability.

[0049]

As is apparent from the above description, according to the first aspect of the present invention, the overheating protection means is provided, and the power loss generated in the switching element allows the driving device of the brushless motor to be driven. When heat is generated and reaches a predetermined temperature, the overheat protection means acts on a PWMDUTY command signal input terminal to reduce or reduce the voltage value of a signal input to the input terminal, thereby turning on the switch element.
Since the period is limited or turned off, even if the driving device of the brushless motor generates heat due to the power loss generated in the switch element, the temperature rise can be suppressed to a predetermined temperature or less.

According to the second aspect of the present invention, the overheat protection means is configured such that a voltage obtained by dividing a reference voltage by a resistor is inputted to one input terminal, and the other input terminal is grounded via a thermistor and a resistor. And a comparator connected to a reference voltage via a resistor, and an output terminal connected to a PWMDUTY command signal input terminal of the brushless motor driving device. Is lower than the predetermined temperature, the output of the comparator is switched from LOW to open, and the switch element can be returned from OFF to ON again.

According to the third aspect of the present invention, the overheat protection means is configured such that a voltage obtained by dividing a reference voltage by a resistance is input to one input terminal, and the other input terminal is grounded via a thermistor and a resistor. And a hysteresis comparator whose output terminal is connected to a reference voltage via a resistor and whose output terminal is connected to a PWMDUTY command signal input terminal of the brushless motor driving device. If the device drops below a predetermined temperature and further down to a second predetermined temperature,
The output of the comparator is switched from LOW to open, and the switch element can be returned from OFF to ON again.

According to the fourth aspect of the present invention, the overheat protection means is provided with a transistor in which a series resistor is connected to the base and a resistor is connected between the base and the emitter, and the resistor is connected in series to the base of the transistor. The other end is PTC
(Positive characteristic) Grounded via a thermistor, connected to a reference voltage via a resistor, the emitter is grounded,
Since the collector was connected to the PWMDUTY command signal input terminal, the power loss generated in the switch element
When the driving device of the brushless motor generates heat and reaches a predetermined temperature, the resistance value of the PTC (positive characteristic) thermistor increases, and the voltage at the other end of the resistor connected in series to the base of the transistor increases. , A current is input to the base of the transistor via the series resistor, the transistor is turned on, and the PW
The voltage of the MDUTY command signal input terminal decreases, the ON period of the switch element is limited, and the temperature rise can be suppressed to a predetermined temperature or less.

According to the fifth aspect of the present invention, the overheat protection means is provided with a transistor having a series resistor connected to the base and a resistor connected between the base and the emitter, and a resistor connected in series to the base of the transistor. Is connected to a reference voltage via a thermistor, grounded via a resistor, the emitter is also grounded, and the collector is connected to P
Since the drive device of the brushless motor generates heat due to power loss generated in the switch element and is connected to the WMDUTY command signal input terminal, when the temperature reaches a predetermined temperature, the resistance value of the thermistor decreases, and the resistance of the thermistor decreases. The voltage at the other end of the series-connected resistor increases, a current is input to the base of the transistor via the series resistor, the transistor is turned on, and the voltage of the PWMDUTY command signal input terminal to which the collector is connected. Is reduced, the ON period of the switch element is limited, and even if the brushless motor driving device generates heat, the temperature rise can be suppressed to a predetermined temperature or less.

According to a sixth aspect of the present invention, there is provided a brushless motor provided with overheat protection means for limiting an ON period of a switch element when a voltage generated in a positive temperature coefficient thermistor reaches a predetermined value. Of the drive unit,
When the driving device of the brushless motor generates heat due to the power loss generated in the switch element and reaches a predetermined temperature, the resistance value of the positive temperature coefficient thermistor increases, and a voltage generated in the PTC (positive characteristic) thermistor with a small current. Reaches a predetermined value, the ON period of the switch element can be limited,
Even if the driving device of the brushless motor generates heat, the temperature rise can be suppressed to a predetermined temperature or less.

According to the invention described in claim 7, according to claim 1,
A brushless motor characterized by incorporating the brushless motor drive device according to any one of claims 1 to 6, wherein the temperature is reduced to a predetermined temperature or less with good responsiveness to any temperature rise factor. The present invention can provide a brushless motor capable of performing the following.

According to the invention as set forth in claims 8 to 10, a brushless motor capable of controlling the temperature to a predetermined temperature or less with good responsiveness is mounted on an air conditioner, an air purifier and a garbage disposal machine. Thereby, the reliability of the electric device can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a brushless motor driving device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a brushless motor driving device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a brushless motor driving device according to a third embodiment of the present invention;

FIG. 4 is a configuration diagram of a brushless motor driving device according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a brushless motor driving device according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of a brushless motor driving device according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a brushless motor according to a seventh embodiment of the present invention.

FIG. 8 is a configuration diagram of an air conditioner according to an eighth embodiment of the present invention.

FIG. 9 is a configuration diagram of an air purifier according to a ninth embodiment of the present invention.

FIG. 10A is a diagram showing a temperature characteristic of a resistance value of the thermistor according to the second embodiment of the present invention. FIG. 10B is a diagram showing a temperature characteristic of an input voltage of the third comparator.

11A is a diagram illustrating a temperature rise characteristic of a motor driving device according to a third embodiment of the present invention. FIG. 11B is a diagram illustrating a temperature rising characteristic of a motor driving device according to a third embodiment of the present invention. Temperature rise characteristic diagram of motor drive device

FIG. 12A is a diagram showing a temperature characteristic of a resistance value of the thermistor according to the third embodiment of the present invention. FIG. 12B is a diagram showing a temperature characteristic of an input voltage of the third comparator.

FIG. 13A is a diagram showing a temperature characteristic of the resistance value of the thermistor according to the fifth embodiment of the present invention. FIG.

FIG. 14 is a circuit diagram of a conventional motor drive device.

FIG. 15 is a block diagram of a conventional motor drive device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brushless motor 2 DC power supply 3 PWMDUTY command signal 4 PWM formation part 5 Inverter circuit part 5a, 5b, 5c, 5d, 5e, 5f Switch element 6 1 chip IC 7 Overheat protection means 8 Control power supply 9 Series resistance 10 Regulator 11 Overcurrent Detection circuit 12 Three-phase distribution circuit 13 Gate drive circuit 14 Current detection resistor 15 First reference power supply output terminal 16 PWMDUTY command signal input terminal 17 Triangular wave oscillator 18 Second reference power supply 19 First comparator 20 Second comparator 21 First Third comparator 22 First resistor 23 Second resistor 24 Third resistor 25 Fourth resistor 26 Thermistor 27 Ninth resistor 28 First transistor 29 Second transistor 30 Diode 31 Fifth resistor 32 Third Transistor of 33 Hysteresis Portion 34 Sixth resistor 35 Seventh resistor 36 Eighth resistor 37 PTC thermistor (positive characteristic thermistor) 38 Ninth resistor 39 Rotor assembly 40 Shaft 41 Yoke 42 Magnet 43 Bearing 44 Bracket 45 Heat dissipation silicon 46 Printed circuit board 47 Heat conductive material 48 Mold assembly 49 Stator core 50 Winding 51 Insulator 52 Fixed PIN 53 Terminal PIN 54 Air conditioner indoor unit 55 Air conditioner outdoor unit 56 Cross flow fan 57 Propeller fan 58 Refrigerant pipe 59 Air purifier 60 Sirocco fan

Claims (10)

[Claims] 1. A plurality of switches which use a DC power supply as a power source and variably control the ratio of an ON period / OFF period by an operation of a PWM forming unit in which a DUTY ratio is varied by an externally input PWMDUTY command signal. In a brushless motor drive device that supplies power to the brushless motor via the element, an overheat protection unit is provided, and the power loss generated in the switch element causes the brushless motor drive device to generate heat and reach a predetermined temperature. At this time, the overheat protection means acts on the PWMDUTY command signal input terminal to reduce or set the analog voltage value input to the input terminal to zero voltage, thereby limiting or turning off the ON period of the switch element. A drive device for a brushless motor, characterized in that: 2. An overheat protection means, wherein a voltage obtained by dividing a resistance from a reference voltage is inputted to one input terminal, and the other input terminal is grounded via a thermistor and a resistor.
2. The brushless motor driving device according to claim 1, wherein the driving device comprises a comparator connected to a reference voltage via a resistor and having an output terminal connected to a PWMDUTY command signal input terminal of the brushless motor driving device. 3. An overheat protection means, wherein a voltage obtained by dividing a reference voltage by a resistor is inputted to one input terminal, and the other input terminal is grounded via a thermistor and a resistor.
2. The brushless motor driving device according to claim 1, wherein a hysteresis comparator connected to a reference voltage via a resistor and having an output terminal connected to a PWMDUTY command signal input terminal of the brushless motor driving device is provided. 4. An overheat protection means, a transistor having a base connected with a series resistor and a resistor connected between the base and the emitter is provided, and the other end of the resistor connected in series with the base of the transistor is provided with a positive temperature coefficient thermistor. 2. The brushless motor driving device according to claim 1, wherein the brushless motor is grounded via a resistor, connected to a reference voltage via a resistor, the emitter is grounded, and the collector is connected to a PWMDUTY command signal input terminal. 5. The overheat protection means includes a transistor having a base connected to a series resistor and a resistor connected between the base and the emitter, and the other end of the resistor connected in series to the base of the transistor is connected via a thermistor. 2. The brushless motor driving device according to claim 1, wherein the brushless motor is connected to a reference voltage, grounded via a resistor, the emitter is also grounded, and the collector is connected to a PWMDUTY command signal input terminal. 6. A brushless motor driving device, comprising: overheat protection means for limiting an ON period of a switch element when a voltage generated in a PTC thermistor reaches a predetermined value. 7. A brushless motor, comprising the brushless motor driving device according to claim 1. 8. An air conditioner, wherein the brushless motor according to claim 7 is used for blowing air. 9. An air cleaner, wherein the brushless motor according to claim 7 is used for blowing air. 10. A garbage disposal machine, wherein the brushless motor according to claim 7 is used for blowing air.