JP6887560B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner including a protection circuit that stops driving the motor and protects the motor when an overcurrent flowing through the motor is detected.

The heater / cooler disclosed in Patent Document 1 has a current detection unit that detects the current flowing through the motor, and when the value of the current detected by the current detection unit is equal to or greater than the set value, it is said that an overcurrent is flowing through the motor. It is provided with an operation control unit that determines and stops the operation of the motor. The overcurrent is a current having a value exceeding the rated current of the motor.

Japanese Unexamined Patent Publication No. 6-123514

However, in the technique disclosed in Patent Document 1, the overcurrent protection function of the operation control unit is realized by executing the program by the microcomputer. Therefore, there is a problem that if an erroneous program is written to the microcomputer or if there is an erroneous program, the overcurrent protection function may not operate normally and the operation of the motor may not be stopped.

The present invention has been made in view of the above, and an object of the present invention is to obtain an air conditioner capable of improving the reliability of the overcurrent protection function.

In order to solve the above-mentioned problems and achieve the object, the air conditioner according to the present invention includes a motor, a first drive circuit that generates a first signal for driving the motor, and a motor based on the first signal. Based on the second drive circuit that generates the second signal to drive the motor and the information that depends on the current flowing through the motor, if it is determined that the motor is in an abnormal state, the second signal in the second drive circuit is generated. It includes a signal generation stop circuit for stopping and a temperature detection unit for detecting the temperature of the motor . The signal generation stop circuit compares the temperature detected by the temperature detection unit with the voltage for temperature determination, and when it is determined that the temperature of the motor has risen to a value determined to be abnormal, the signal generation stop circuit sets the second drive circuit. By lowering the power supply voltage for driving, the generation of the second signal in the second driving circuit is stopped.

The air conditioner according to the present invention has an effect that the reliability of the overcurrent protection function can be improved.

The figure which shows the structure of the air conditioner which concerns on Embodiment 1 of this invention. A flowchart for explaining an overcurrent protection operation in the air conditioner according to the first embodiment of the present invention. The figure which shows the structure of the air conditioner which concerns on Embodiment 2 of this invention. The figure which shows the structure of the air conditioner which concerns on Embodiment 3 of this invention. A flowchart for explaining an overcurrent protection operation in the air conditioner according to the third embodiment of the present invention. The figure which shows the structure of the air conditioner which concerns on Embodiment 4 of this invention. A flowchart for explaining an overcurrent protection operation in the air conditioner according to the fourth embodiment of the present invention. The first figure for demonstrating the example of the mounting place of the thermistor shown in FIG. The second figure for demonstrating the example of the mounting place of the thermistor shown in FIG.

Hereinafter, the air conditioner according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a diagram showing a configuration of an air conditioner according to a first embodiment of the present invention. The air conditioner 100 according to the first embodiment includes a motor driving device 200 and a motor 7 driven by the motor driving device 200. In addition to the motor drive device 200 and the motor 7, the air conditioner 100 includes, for example, a compressor for compressing a refrigerant, a blower fan, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, a refrigerant pipe, and the like. Be prepared. The description of the configurations other than the motor drive device 200 and the motor 7 will be omitted. The motor 7 is used, for example, for a compressor of an air conditioner, a blower fan, or the like.

The motor drive device 200 is a power conversion device that converts the AC power supplied from the AC power supply 1 into AC power having a frequency at which the motor 7 can be driven. The motor 7 is an AC motor driven by AC power supplied from the motor drive device 200.

The motor drive device 200 includes a noise filter circuit 2, a diode bridge 3, an electrolytic capacitor 4, a drive device 5, a current detector 10, a timer circuit 14, and a microcomputer 13. The microcomputer 13 is abbreviated as "microcomputer" in FIG.

One end of the first AC wiring 20 is connected to the AC power supply 1, and the other end of the first AC wiring 20 is connected to the first input terminal 2a of the noise filter circuit 2. Further, one end of the second AC wiring 21 is connected to the AC power supply 1, and the other end of the second AC wiring 21 is connected to the second input terminal 2b of the noise filter circuit 2.

The noise filter circuit 2 is a circuit for preventing the conductive noise generated in the AC power supply 1 from affecting the drive device 5 or the like which is the second drive circuit. The drive device 5 generates a drive signal 8a for driving the motor based on the control signal 11.

One end of the third AC wiring 22 is connected to the first output terminal 2c of the noise filter circuit 2, and the other end of the third AC wiring 22 is connected to the first input terminal 3a of the diode bridge 3. One end of the fourth AC wiring 23 is connected to the second output terminal 2d of the noise filter circuit 2, and the other end of the fourth AC wiring 23 is connected to the second input terminal 3b of the diode bridge 3.

The diode bridge 3 is a full-wave rectifier circuit configured by combining four diodes. The configuration of the diode bridge 3 is not limited to that configured by combining diodes, and may be configured by combining a plurality of MOSFETs (Metal Oxide Semiconductor-Field Effect Transistors).

One end of the first DC bus 31 is connected to the first output terminal 3c of the diode bridge 3. The other end of the first DC bus 31 is connected to the first input terminal 5a of the drive device 5. One end of the second DC bus 32 is connected to the second output terminal 3d of the diode bridge 3. The other end of the second DC bus 32 is connected to the second input terminal 5b of the drive device 5.

The first DC bus 31 is a wiring on the high potential side provided between the diode bridge 3 and the drive device 5. The second DC bus 32 is a wiring on the low potential side provided between the diode bridge 3 and the drive device 5.

The drive device 5 is a power module including a drive circuit 6 composed of a plurality of semiconductor switching elements and a control IC (Intelligent Circuit) 8. The control IC 8 outputs a signal for controlling the switching operation of the plurality of semiconductor switching elements to the drive circuit 6.

One end of the electrolytic capacitor 4 is connected to the first DC bus 31, and the other end of the electrolytic capacitor 4 is connected to the second DC bus 32.

The current detector 10 detects the current flowing through the second DC bus 32. The current information indicating the value of the detected current is input to the control IC 8 via the timer circuit 14. The current detector 10 may be a current sensor using a current transformer for an instrument called a CT (Curent Transformer), or may be a current sensor using a shunt resistor. Further, the current detector 10 may be a combination of these. The location of the current detector 10 may be the first DC bus 31, or the AC wiring provided between the drive device 5 and the motor 7.

In the motor drive device 200 configured in this way, the AC voltage applied from the AC power supply 1 to the diode bridge 3 is full-wave rectified, and the full-wave rectified voltage is smoothed by the electrolytic capacitor 4 and applied to the drive device 5. Will be done. The voltage applied to the drive device 5 is converted into an AC voltage by the switching operation of the switching element of the drive circuit 6 and applied to the motor 7.

The control IC 8 outputs a drive signal 8a having a waveform similar to that of the control signal 11 output from the microcomputer 13 which is the first drive circuit. The control signal 11 is a PWM (Pulse Width Modulation) signal. The control signal 11 is a first signal for driving the motor 7. The drive signal 8a is a signal in which the control signal 11 is converted into a voltage having a value at which the switching element of the drive circuit 6 can be driven. The drive signal 8a is a second signal for driving the motor 7.

The control IC 8 includes a protection circuit 9. The protection circuit 9 is a circuit for preventing the motor 7 from failing due to an overcurrent flowing through the windings constituting the motor 7, for example.

When the protection circuit 9 detects the occurrence of an overcurrent based on the signal output from the timer circuit 14, the protection circuit 9 outputs an error signal 12 to the microcomputer 13. The timer circuit 14 is a signal generation stop circuit that stops the generation of the second signal in the second drive circuit. The error signal 12 is an electric signal that takes a binary potential of high level or low level. The Low level error signal 12 indicates that no overcurrent has occurred. The high level error signal 12 indicates that an overcurrent has occurred.

Further, when the protection circuit 9 detects the occurrence of an overcurrent based on the signal output from the timer circuit 14, even if the control signal 11 is output from the microcomputer 13, the control IC 8 generates the drive signal 8a. Stop it.

The timer circuit 14 includes a determination unit 16 and a holding unit 15.

The determination unit 16 is realized by, for example, a comparator, and the determination unit 16 compares the overcurrent determination value with the current value detected by the current detector 10.

The determination unit 16 outputs a Low level electric signal when the current detected by the current detector 10 does not exceed the overcurrent determination value. Further, the determination unit 16 outputs a high level electric signal when the current detected by the current detector 10 exceeds the overcurrent determination value. The high level electric signal is the first overcurrent generation information. In this way, the determination unit 16 outputs an electric signal that takes a binary potential of high level or low level depending on the comparison result.

The holding unit 15 is realized by, for example, a switch and a timer. The switch may be a semiconductor switching element or a switch having mechanical contacts to open and close.

When the switch of the holding unit 15 is a semiconductor switching element, the semiconductor switching element is turned off when the first overcurrent generation information is not received, and outputs a Low level electric signal. Further, when the semiconductor switching element receives the first overcurrent generation information, it is turned on until a certain time n elapses from the time when the first overcurrent generation information is received, and outputs a high level electric signal. The time from the time when the first overcurrent generation information is received until a certain time n elapses is measured by the timer included in the holding unit 15. The details of the fixed time n will be described later.

When the switch of the holding unit 15 is a switch, the switch is turned off when the first overcurrent generation information is not received, and outputs a Low level electric signal. When the switch receives the first overcurrent generation information, the switch is turned on until a certain period of time n elapses from the time when the first overcurrent generation information is received, and outputs a high level electric signal.

In this way, the holding unit 15 outputs an electric signal that takes a binary potential of high level or low level to the protection circuit 9. The high level electric signal output from the holding unit 15 is the second overcurrent generation information. The second overcurrent generation information is the first stop signal for stopping the generation of the drive signal 8a.

Next, the overcurrent protection operation of the air conditioner 100 will be described with reference to FIG. FIG. 2 is a flowchart for explaining an overcurrent protection operation in the air conditioner according to the first embodiment of the present invention.

After the operation of the air conditioner 100 shown in FIG. 1 is started, the timer circuit 14 determines whether or not the current I detected by the current detector 10 exceeds the overcurrent determination value Is (step S1).

When the current I detected by the current detector 10 does not exceed the overcurrent determination value Is (steps S1 and No), the timer circuit 14 outputs a Low level electric signal to the protection circuit 9 (step S2).

At this time, the control IC 8 continues to generate the drive signal 8a based on the control signal 11 output from the microcomputer 13 (step S3).

The processing of steps S1, S2, and S3 is repeated until the current I exceeds the overcurrent determination value Is.

For example, when the bearing of the motor 7 during operation is seized, the rotation of the rotor of the motor 7 is hindered, and an overcurrent flows through the winding wound around the motor 7. Therefore, the value of the current detected by the current detector 10 increases.

When the current I detected by the current detector 10 exceeds the overcurrent determination value Is (steps S1 and Yes), the determination unit 16 of the timer circuit 14 outputs the first overcurrent generation information to the holding unit 15 (steps S1, Yes). Step S4).

The holding unit 15 that has received the first overcurrent generation information outputs the second overcurrent generation information to the protection circuit 9 (step S5).

The protection circuit 9 that detects the occurrence of the overcurrent by receiving the second overcurrent generation information outputs the error signal 12 to the microcomputer 13 and stops the generation of the drive signal 8a by the control IC 8 (step S6). ..

By the operation of step S6, for example, even when the control signal 11 is continuously output from the microcomputer 13 without detecting the occurrence of the overcurrent in the microcomputer 13 to which the error signal 12 is input, the control IC 8 is used. The generation of the drive signal 8a is stopped, and the drive of the motor 7 is stopped.

The holding unit 15 determines whether or not a certain period of time n has elapsed since the output of the second overcurrent generation information was started (step S7). If n has not elapsed for a certain period of time (steps S7, No), the processes from step S5 to step S7 are repeated.

When a certain time n has elapsed since the output of the second overcurrent generation information is started (steps S7 and Yes), the holding unit 15 outputs a Low level electric signal to the protection circuit 9 by the process of step S2. As a result, the generation of the drive signal 8a is restarted.

The fixed time n is the lower limit of the time during which the temperature of the winding does not reach an excessively high temperature even if the temperature of the winding of the motor 7 rises in a situation where the operation of the motor 7 is repeatedly stopped and restarted, for example. The upper limit is the time for recovering from the error of the air conditioner 100, the time for not significantly impairing the operating ability of the air conditioner 100, and the like. The time for error recovery is, for example, a recovery grace time preset in the air conditioner 100. The recovery grace time is set to a value that can completely open the capacitor involved in the logical determination of operation in the internal circuit of the air conditioner 100, for example, when the air conditioner 100 is stopped due to the flow of an overcurrent. Will be done. By setting the time for error recovery, the air conditioner 100 stopped due to the occurrence of overcurrent can be safely recovered after the condenser is completely opened. Further, since the cooling / heating capacity per unit time is impaired as the stop time of the air conditioner 100 becomes longer, the loss of the air conditioning capacity per unit time can be tolerated for a time that does not significantly impair the operating capacity of the air conditioner 100. Set to time. Specifically, when the upper limit of the winding temperature of the motor 7 is 150 degrees in a state where the air conditioner 100 repeatedly stops and returns, the time for stabilizing the winding temperature at 150 degrees or less is 1 minute. The above is required, and the time for error recovery of the air conditioner 100 is 5 minutes or less.

In the air conditioner 100 according to the first embodiment, since the second overcurrent information output from the timer circuit 14 which is the hardware is used, an erroneous program is written in the microcomputer 13 or the program is not corrected. Even in such a case, the overcurrent protection of the motor 7 is possible.

Further, in the air conditioner 100 according to the first embodiment, since the output time of the second overcurrent information in the holding unit 15 can be arbitrarily changed, even if the change in the temperature of the winding differs depending on the motor 7, the winding The time for stopping the motor 7 can be adjusted so that the temperature does not rise excessively.

Further, in the air conditioner 100 according to the first embodiment, the microcomputer 13, the timer circuit 14, and the protection circuit 9 whose operation is guaranteed by the manufacturer are used. Therefore, the functions realized by these circuits are safe. Moreover, the motor can be stopped reliably.

Further, in the air conditioner 100 according to the first embodiment, overcurrent protection is possible by using the microcomputer 13 and the timer circuit 14, so that when only one of the microcomputer 13 and the timer circuit 14 is used. In comparison, the reliability of overcurrent protection is improved.

Further, in the air conditioner 100 according to the first embodiment, when an overcurrent occurs, the error signal 12 continues to be transmitted for a certain period of time. Therefore, the length of the error signal 12 generation time can be used to identify the cause of the overcurrent. It can be used.

Embodiment 2.
FIG. 3 is a diagram showing a configuration of an air conditioner according to a second embodiment of the present invention. The air conditioner 100A according to the second embodiment includes a motor drive device 200A instead of the motor drive device 200.

The motor drive device 200A includes a drive device 5A which is a second drive circuit, a control IC 8A, and a protection circuit 9A instead of the drive device 5, the control IC 8 and the protection circuit 9. Other configurations are the same as or equivalent to the configuration of the first embodiment, and the same or equivalent components are designated by the same reference numerals, and redundant description will be omitted.

The current information output from the current detector 10 is input not only to the timer circuit 14 but also to the protection circuit 9A.

For example, if the current detected by the current detector 10 does not exceed the overcurrent determination value set in the protection circuit 9A, the protection circuit 9A determines that no overcurrent has occurred and an error signal. 12 is not output. When the current detected by the current detector 10 exceeds the overcurrent determination value, it is determined that an overcurrent has occurred, and the generation of the drive signal 8a by the control IC 8A is stopped.

Further, when the protection circuit 9A does not receive the second overcurrent generation information from the timer circuit 14, it determines that no overcurrent has occurred and does not output the error signal 12. Further, when the protection circuit 9A receives the second overcurrent generation information from the timer circuit 14, it determines that the overcurrent has occurred and stops the generation of the drive signal 8a by the control IC 8A.

The protection circuit 9A outputs an error signal 12 and drives the protection circuit 9A in either the case where the current detected by the current detector 10 exceeds the overcurrent determination value or the case where the second overcurrent generation information is received. The generation of the signal 8a is stopped, and the error signal 12 is not output in other cases.

According to the air conditioner 100A according to the second embodiment, the overcurrent can be determined by using the current detected by the current detector 10 in addition to the second overcurrent generation information from the timer circuit 14. Therefore, the reliability of the air conditioner 100A is improved because the occurrence of the overcurrent can be detected even faster than in the case where the overcurrent determination is performed using only the timer circuit 14.

Embodiment 3.
FIG. 4 is a diagram showing a configuration of an air conditioner according to a third embodiment of the present invention. The air conditioner 100B according to the third embodiment includes a motor drive device 200B instead of the motor drive device 200A of the second embodiment.

The motor drive device 200B includes a timer circuit 14A which is a signal generation stop circuit instead of the timer circuit 14. The timer circuit 14A includes a holding unit 15A. Other configurations are the same as or equivalent to the configuration of the second embodiment, and the same or equivalent components are designated by the same reference numerals, and duplicate description will be omitted.

Like the holding unit 15, the holding unit 15A is realized by, for example, a switch and a timer.

When the switch of the holding unit 15A is a semiconductor switching element, the semiconductor switching element is turned off when the error signal 12 output from the protection circuit 9A is not received, and outputs a Low level electric signal. Further, when the semiconductor switching element receives the error signal 12, it is turned on until a certain period of time n elapses from the time when the error signal 12 is received, and outputs a high level electric signal. The time from the time when the error signal 12 is received until a certain time n elapses is measured by the timer.

When the switch of the holding unit 15A is a switch, the switch turns off when the error signal 12 is not received, and outputs a Low level electric signal. When the switch 12 receives the error signal 12, the switch is turned on until a certain period of time n elapses from the time when the error signal 12 is received, and outputs a high level electric signal.

In this way, the holding unit 15A outputs an electric signal having a binary potential of high level or low level to the protection circuit 9A. The high level electric signal output from the holding unit 15A is overcurrent generation information. The overcurrent generation information is a first stop signal for stopping the generation of the drive signal 8a.

Next, the overcurrent protection operation of the air conditioner 100B will be described with reference to FIG. FIG. 5 is a flowchart for explaining an overcurrent protection operation in the air conditioner according to the third embodiment of the present invention.

After the operation of the air conditioner 100B is started, the protection circuit 9A determines whether or not the current I detected by the current detector 10 exceeds the overcurrent determination value Is (step S11).

When the current I detected by the current detector 10 does not exceed the overcurrent determination value Is (steps S11 and No), the protection circuit 9A permits the control IC 8A to generate the drive signal 8a (step S12).

The processes of steps S11 and S12 are repeated until the current I exceeds the overcurrent determination value Is.

When the current I detected by the current detector 10 exceeds the overcurrent determination value Is (step S11, Yes), the protection circuit 9A stops the generation of the drive signal 8a by the control IC 8A and outputs the error signal 12. (Step S13).

The holding unit 15A that has received the error signal 12 outputs the overcurrent generation information to the protection circuit 9A for a certain period of time (step S14).

The protection circuit 9A continues to output the error signal 12 to the microcomputer 13 when the overcurrent generation information from the holding unit 15A is output, and further stops the generation of the drive signal 8a by the control IC 8A. (Step S15).

The holding unit 15A determines whether or not a certain period of time n has elapsed since the output of the overcurrent generation information was started (step S16). If n has not elapsed for a certain period of time (steps S16, No), the processes from step S14 to step S16 are repeated.

When a certain time n has elapsed since the output of the overcurrent generation information is started (steps S16, Yes), the holding unit 15A outputs a Low level electric signal to the protection circuit 9A. As a result, the generation of the drive signal 8a is restarted.

In the air conditioner 100B according to the third embodiment, the same effect as that of the first embodiment can be obtained. Further, in the air conditioner 100B according to the third embodiment, even if the current information detected by the current detector 10 fluctuates depending on the current value, the current information has two values of high level or low level by the protection circuit 9A. It is converted into an error signal 12 that takes the potential of. Therefore, the reliability of the overcurrent determination in the timer circuit 14A is improved.

Embodiment 4.
FIG. 6 is a diagram showing a configuration of an air conditioner according to a fourth embodiment of the present invention. The air conditioner 100C according to the fourth embodiment includes a motor drive device 200C. Hereinafter, the configurations are the same as or equivalent to those of the first to third embodiments, and the same or equivalent components are designated by the same reference numerals, and redundant description will be omitted.

The motor drive device 200C includes a thermistor 17, a determination circuit 18, and an opening / closing circuit 40. The determination circuit 18 and the switching circuit 40 form a signal generation stop circuit for stopping the generation of the second signal in the second drive circuit.

The thermistor 17, which is a temperature detection unit, detects the temperature of the motor 7 and outputs temperature information indicating the temperature. The mounting location of the thermistor 17 will be described later.

By comparing the temperature information from the thermistor 17 with the voltage 19 for determining the winding temperature, the determination circuit 18 raises the temperature of the winding of the motor 7 to a value determined to be abnormal, and the motor 7 is abnormal. Judge whether or not it is in such a state.

When the determination circuit 18 determines that the motor 7 is not in an abnormal state, the opening / closing circuit 40 maintains the open state. When the determination circuit 18 determines that the motor 7 is in an abnormal state, the opening / closing circuit 40 changes from the open state to the closed state.

The switching circuit 40 is provided between the first resistor 42 and the second resistor 43. The first resistor 42 and the second resistor 43 are resistors for dividing the voltage output from the drive power supply 41 for the drive device 5A.

When the opening / closing circuit 40 is in the open state, the drive power supply 41 is applied to the drive device 5A. Since the first resistor 42 and the second resistor 43 are connected in series when the switching circuit 40 is in the closed state, the voltage applied to the drive device 5A is lower than when the switching circuit 40 is in the open state. It becomes a value.

Next, the overcurrent protection operation of the air conditioner 100C will be described with reference to FIG. 7. FIG. 7 is a flowchart for explaining an overcurrent protection operation in the air conditioner according to the fourth embodiment of the present invention.

After the operation of the air conditioner 100C shown in FIG. 6 is started, the determination circuit 18 determines whether or not the temperature T detected by the thermistor 17 exceeds the winding temperature determination voltage Tth (step S21). ..

When the temperature T does not exceed the voltage Tth (steps S21 and No), it is determined that the motor 7 is not in an abnormal state, and an electric signal taking a low level potential is output (step S22).

Since the drive power supply 41 is applied to the control IC 8A, the control IC 8A continues to generate the drive signal 8a (step S23).

When the temperature T exceeds the voltage Tth (steps S21, Yes), it is determined that the motor 7 is in an abnormal state, and an electric signal having a high level potential is output. The high level electric signal is overcurrent generation information (step S24).

The switching circuit 40 that has received the overcurrent generation information changes from the open state to the closed state (step S25). As a result, the voltage divided by the first resistor 42 and the second resistor 43 is applied to the control IC 8A, and the generation of the drive signal 8a is stopped in the control IC 8A (step S26). After step S26, the processes after step S21 are repeated.

FIG. 8 is a first diagram for explaining an example of the mounting location of the thermistor shown in FIG. FIG. 8 shows a compressor 300 in which the motor 7 shown in FIG. 6 is built. What is shown by 301 and 302 in FIG. 8 is a thermistor.

The thermistor 301 is installed on the surface of the refrigerant blowing pipe 310 of the compressor 300. The refrigerant compressed by the compressor 300 and having a high temperature passes through the refrigerant blowing pipe 310. By providing the thermistor 301 in the refrigerant blowing pipe 310, the temperature of the winding of the motor 7 can be indirectly measured.

The thermistor 302 is installed on the surface of the frame 311 of the compressor 300. Since the temperature of the high temperature refrigerant and the temperature generated by the motor 7 are transmitted to the surface of the frame 311, the temperature of the winding of the motor 7 is indirectly measured by providing the thermistor 302 on the frame 311. Can be done.

FIG. 9 is a second diagram for explaining an example of the mounting location of the thermistor shown in FIG. The fan motor 700 shown in FIG. 9 uses the motor 7 shown in FIG. 6 as a blower motor.

Those represented by reference numerals 701 to 705 in FIG. 9 are thermistors.

The thermistor 701 is installed on the outer peripheral surface 710 of the fan motor 700. The thermistor 702 is installed on the first end surface 720 in the axial direction of the fan motor 700. The thermistor 703 is installed on the second end surface 730 of the fan motor 700 in the axial direction. The thermistor 704 is installed on the outer peripheral surface of the bearing housing 740 of the fan motor 700. The thermistor 705 is installed inside the housing of the fan motor 700.

By installing the thermistor in the fan motor 700 in this way, the temperature of the winding of the motor 7 can be indirectly measured.

In the determination circuit 18 and the switching circuit 40 of the air conditioner 100C according to the fourth embodiment, the temperature detected by the temperature detection unit is compared with the voltage for temperature determination, and the temperature of the motor is determined to be abnormal. When it is determined that the temperature has risen to the above, the power supply voltage for driving the second drive circuit is lowered to stop the generation of the second signal in the second drive circuit. With this configuration, the operation of the control IC 8A can be stopped, so that even if an erroneous program is written to the microcomputer 13 or there is an omission of correction of the program, the overcurrent of the motor 7 can be protected and the coil can be wound. When the temperature of the wire shows an abnormal value, the operation of the control IC 8A can be stopped. Therefore, the reliability of the air conditioner 100C is improved as compared with the case where the overcurrent protection operation is performed using only the microcomputer 13.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 AC power supply, 2 noise filter circuit, 2a, 3a, 5a 1st input terminal, 2b, 3b, 5b 2nd input terminal, 2c 1st output terminal, 2d 2nd output terminal, 3 diode bridge, 4 electrolytic capacitor, 5 , 5A drive device, 6 drive circuit, 7 motor, 8,8A control IC, 8a drive signal, 9,9A protection circuit, 10 current detector, 11 control signal, 12 error signal, 13 microcomputer, 14, 14A timer circuit , 15, 15A holding part, 16 judgment part, 17,301,302,701,702,703,704,705 thermistor, 18 judgment circuit, 19 voltage, 20 1st AC wiring, 21 2nd AC wiring, 22 3rd AC wiring, 23 4th AC wiring, 31 1st DC bus, 32 2nd DC bus, 40 switch circuit, 41 drive power supply, 42 1st resistor, 43 2nd resistor, 100, 100A, 100B, 100C air conditioner, 200, 200A, 200B, 200C motor drive, 300 compressor, 310 refrigerant blow pipe, 311 frame, 700 fan motor, 710 outer peripheral surface, 720 first end face, 730 second end face, 740 bearing housing.

Claims (3)

With the motor
A first drive circuit that generates a first signal to drive the motor,
A second drive circuit that generates a second signal for driving the motor based on the first signal, and
When it is determined that the motor is in an abnormal state based on the information depending on the current flowing through the motor, the signal generation stop circuit for stopping the generation of the second signal in the second drive circuit and the signal generation stop circuit.
A temperature detection unit that detects the temperature of the motor,
Equipped with a,
When the signal generation stop circuit compares the temperature detected by the temperature detection unit with the voltage for determining the temperature and determines that the temperature of the motor has risen to a value determined to be abnormal, the first by lowering the power supply voltage for driving the second driving circuit, an air conditioner Ru stops the generation of the second signal in the second drive circuit. Equipped with a current detector that detects the current flowing through the motor
The signal generation stop circuit uses the current detected by the current detector to generate a first stop signal for stopping the generation of the second signal.
The air conditioner according to claim 1, wherein the second drive circuit uses the current detected by the current detector to stop the generation of the second signal. The second drive circuit uses the current detected by the current detector to stop the generation of the second signal and generate the second stop signal to stop the generation of the second signal. Output to the signal generation stop circuit,
The air conditioner according to claim 2, wherein the signal generation stop circuit generates the first stop signal based on the second stop signal.

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