JPH0888994A - Air conditioner - Google Patents

Abstract

PURPOSE: To prevent the breakdown of an electric part caused by heating by providing a plurality of switching elements, which turn ON and OFF the current flowing through a stator winding in correspondence with the position of a rotor magnetic pole detected with a position detecting circuit, and detecting the locked state of a brushless fan motor. CONSTITUTION: After a starting command for a fan motor 4 is inputted from an external circuit, the fan motor 4 is rotated by the wind blowing toward the fan. Then, the counter-electromotive force is generated from the fan motor 4 and inputted into a position detecting circuit 12 through a filter circuit 9, and the detected rotor-pole position signal is outputted. The signal is detected for the specified time with a number-of-rotation setting circuit 11. A current, which is made to flow through a stator winding in correspondence with the detected rotor pole position, is turned ON and OFF with a plurality of switching elements 3. The locked state of the fan motor is detected by the detected position signal, and the signal is transferred into a compressor driving control circuit 14. Thus, the driving of a compressor 15 is stopped. Therefore, the breakdown of the part caused by heating can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly to control of a motor for driving a fan provided in an outdoor unit or an indoor unit, and enables detection of lock of the motor. Controlling a brushless fan motor.

[0002]

2. Description of the Related Art Conventionally, an induction motor has been generally used as a fan motor mounted on an outdoor unit or an indoor unit of an air conditioner. A fan motor using a brushless motor is also used, but the rotor position is detected by a hall element.

A sensorless brushless motor has been implemented as described in Japanese Patent Publication No. 55-26793. Brushless motors are known to have various starting methods, and the common points of these various starting methods are all
The position of the magnetic pole of the rotor is detected, and the brushless operation of generating a rotational torque by appropriately switching the current of the stator winding by using this signal is performed.

There are two methods for detecting the position of the rotor magnetic pole. The first method uses a hall element or an oscillating coil. In these methods, the rotor is stopped. Also, since the rotor magnetic pole position can be detected,
Although the number of parts is large, the motor can be started easily.

The second method is to detect the rotor magnetic pole position by the voltage induced by the rotor magnetic pole in the stator winding, and to determine the current in the stator winding according to the rotor magnetic pole position. The system is switched appropriately and started up. In this system, no induced voltage is generated in the stator winding when the rotor is stopped, so that the rotor magnetic pole position cannot be detected. Therefore, the motor cannot be activated, and some means for activating the motor is required. If the motor is started by some means and accelerated to a certain speed, then the position of the rotor magnetic pole is detected by the induced voltage in the stator winding, and the position of the rotor magnetic pole is detected according to this rotor magnetic pole position. The operation of appropriately switching the current of the stator winding (brushless operation) is continued.

The driving method described below belongs to the second method, and an example of a general brushless motor driving circuit is shown in FIG. 8 for understanding the driving method.

In FIG. 8, WA, WB, and WC are Y connections 3
It is a phase stator winding, and the other ends of the windings are connected to the collectors of power transistors TA, TB and TC, respectively. These stator windings WA, WB, WC and power transistors TA,
At the connection point with TB and TC, two pairs of each diode D
Are connected in a direction in which the current flowing from the connection point is blocked, and the other end of this diode D is connected to the other end of the diode connected to the other phase to form two diodes each. 3 pairs of diode are made. Each diode pair is connected to the neutral point of the stator winding through series resistors R1, R2 and R3. A, B,
C is a Schmitt circuit for inputting the voltage flowing through the resistors R1, R2 and R3.

The outputs of the Schmitt circuits A, B and C are connected to the inputs of the Schmitt circuits A, B and C.
The power transistor T of the phase in which the pair is not connected.
Connected to drive A, TB, TC.

When the rotor magnet is rotated by some means, the induced voltage E is applied to the stator windings WA, WB and WC.
A, EB and EC occur. This induced voltage waveform is shown in FIG. The polarity of the induced voltage defines that the polarity shown in the stator winding WA in FIG. 8, that is, the induced voltage in the direction of blocking the current flowing from the power source is +. When the induced voltage is + and a current flows in, torque is generated.

It will be appreciated that the voltage appearing across resistor R1 in FIG. 8 is zero only when the induced voltages EB, EC of the stator windings WB, WC are both negative. Induced voltage EB,
If either or both of Ec are positive, the voltage is in the forward direction of the diode, so that the voltage of the polarity shown is generated across the resistor R1.

When a voltage of the indicated polarity appears across the resistor R1, the transistor T1 of the Schmitt circuit A turns on.
N, the transistor T2 is OFF. The transistor T1 is turned off only when the voltage across the resistor R1 becomes zero,
The transistor T2 is turned on. Transistor T2 is ON
Then, since the base current of the power transistor TA flows, the power transistor TA is turned on and the phase A is energized.

That is, the A-phase stator winding WA is energized when the induced voltages EB and EC are both negative at time t _{1 in} FIG.
From time t ₂ to electrical angle 60 °. During this time, since the induced voltage EA is +, torque is generated by energization.

Similarly, the stator winding WB is energized from the time t ₃ to the time t ₄ , and the stator winding WC is supplied from the time t ₅ to the time t _6.
It energizes for a period of time to generate torque and continue rotation.

In the circuit of FIG. 8, the energization period of each phase is an electrical angle of 60 °, but FIG. 10 shows a circuit improved to further expand the energization period. In FIG. 10, a bias voltage V1 is applied to the Schmitt circuits A, B, and C by resistors R4 and R5 that divide the power supply voltage.

In FIG. 10, even if a voltage appears across the resistor R1, if the voltage is smaller than V1, the base potential of the transistor T1 becomes lower than the emitter potential, so that the transistor T1 is turned off and therefore the transistor T1 is turned off. T2 is turned on and the power transistor TA is turned on. Due to the action of this bias voltage, the conduction width of each phase is increased as compared with the case of FIG. As shown in FIG. 11, the A-phase stearyl - the motor winding WA is conducting, the induced voltage EB, EC is less time than the bias voltage V1 together, ie the time from the time t ₁ t
_{Between two} . At the same time, the B-phase stator winding WB conducts during the time period t ₃ to the time t ₄ and the C-phase stator winding W W extends.
C conducts between time t ₅ and time t ₆ .

The conduction angle is 1 at maximum depending on the amount of bias.
It can be freely changed within the range of 20 °. FIG. 12 shows a circuit including a motor starting device. The principle configuration of the circuit is the same as in FIG. The difference is that, assuming that the main power supply E1 is a high-voltage power supply, the power transistors TA, T
The transistors other than B and TC use a photo coupler P for coupling the Schmitt circuits A, B and C and the power transistors TA, TB and TC so that transistors of low voltage specifications can be used, and separate from the main power source E1. The low-voltage power supplies E2 and E3 supply power to circuits other than the power transistors TA, TB and TC. Of course, when the main power source E1 is at a low voltage, the entire circuit may be powered only by the main power source as shown in FIG. Schmidt circuit A,
Switches SA and SB are included in the input terminals of B and C.

In order to activate the motor with this circuit, it is necessary to prepare for activation. The reason for the preparation for starting is that the rotor magnetic pole is first placed in a predetermined position. The preparation for starting is achieved by turning on only the switch SB and turning on only the switch SA. First, the transistor T1 of the Schmitt circuit B is turned off, the transistor T2 is turned on, the power transistor TB is turned on, and the B-phase stator winding WB is energized, as described in the explanation of the circuit operation.
When the power transistor TB is turned on, the power supply voltage appears at both ends of the stator winding WB, so that the outputs of the Schmitt circuits A and B become zero due to the function of the diode logic circuit, and the starter winding WA. , WC is not energized.

The rotor magnetic pole is initially located at an arbitrary position,
When the stator winding WB is energized, as shown in FIG.
When the pole provided with the stator winding WB becomes the N pole, the S pole of the rotor is attracted to the pole provided with the stator winding WB, and FIG.
Stand still. However, the initial rotor magnetic pole is shown in FIG.
If it is in the position, the rotor magnetic pole does not move although it is in an unstable state. Next, when the switch SB is turned off and the switch SA is turned on, the south pole of the rotor is attracted to the pole provided with the stator winding WA from either position of FIG. 13 or FIG. It moves to the position of FIG. 15 and stops. With the above, the rotor magnetic pole is located at the predetermined position, and the start preparation is completed.

The activation is performed by turning off the switch SA and turning on the switch SB for a short time. However, the predetermined rotation direction of the motor is in the order of A phase → B phase → C phase.
When the switch SB is turned on, the rotor rotates in the direction of the arrow in FIG. 16, that is, it rotates in the predetermined direction. At this time, the switch SB is turned off before the south pole of the rotor passes through the pole of the stator winding WB.
This is because even if the S pole of the rotor passes through the pole on which the stator winding WB is applied, if the stator winding WB is energized, it will cause a brake to the rotation of the rotor. Because.

Next, as the rotor rotates in the predetermined rotation direction, an induced voltage is generated in the stator windings WA, WB, WC, and the drive circuit uses this induced voltage to position the rotor magnetic pole. Is detected, and the brushless operation is started in which the current of the stator winding is appropriately switched according to the rotor magnetic pole position.

[0021]

When the motor of the prior art described above is used as an outdoor fan motor for driving a fan of an outdoor unit of an air conditioner, the following points have not been taken into consideration. Generally, the fan of the outdoor unit of the air conditioner not only has the effect of blowing air to the outdoor heat exchanger to increase the heat exchange rate, but also to prevent the temperature rise of the parts of the outdoor electrical components built into the outdoor unit. This has the effect of cooling the parts by replacing the air inside the electric parts with the outside air, or by attaching a radiation fin to the electric parts to radiate heat. However, when the fan motor is locked, the outdoor fan motor cannot dissipate heat from the electric parts, and the rise of the temperature of the electric parts causes the parts to be destroyed. In order to prevent this, it is necessary to prevent the heat generation of the electric parts by detecting the locked state of the fan motor and stopping the compressor. However, in the above-mentioned conventional motor, the means for detecting the lock of the fan motor is not taken into consideration, and there is a problem that parts are destroyed due to heat generation.

[0022]

In order to solve the above problems, the present invention provides a compressor, a compressor drive control circuit, a heat exchanger, a fan for blowing air to the heat exchanger, and a fan. In an air conditioner equipped with a driven brushless fan motor, a winding voltage induced in a stator winding by rotation of a rotor magnetic pole in the brushless fan motor is used to rotate the rotor.
A position detecting circuit for detecting the position of the magnetic pole of the rotor; and a plurality of switching elements for electrically connecting and disconnecting the current flowing through the stator winding according to the position of the magnetic pole of the rotor detected by the position detecting circuit. The output signal of the position detection circuit detects the lock state of the brushless fan motor, transfers the signal to the compressor drive control circuit, and the control means for stopping the drive of the compressor is provided to prevent the destruction of electrical parts caused by heat generation. To prevent.

[0023]

The rotational speed of the fan motor is detected by the output signal of the position detecting circuit while driving the fan motor for the air conditioner. When the fan motor is in the locked state, the output signal of the position detection circuit corresponding to the normal rotation speed cannot be obtained, so it is judged that the fan motor is locked due to a failure in the rotation of the fan motor, Stop the drive of the compressor. As a result, the temperature rise of the electric parts is eliminated, and it is possible to prevent the electric parts from being destroyed due to heat generation. Further, since the fan motor drive circuit outputs the fan motor lock signal when the fan motor is locked and the means for communicating with the compressor drive control circuit is provided, it is possible to stop the compressor when the fan is locked. . Further, when the fan motor is locked, the compressor drive control circuit may reduce the rotation speed of the compressor by the output fan motor lock signal to reduce the temperature rise of the electric parts and prevent the electric parts from being destroyed. .

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 3 is a circuit block diagram. The counter electromotive force generated by rotating the rectifier circuit 1 for rectifying and smoothing the commercial AC power source and outputting it, the internal power source circuit 13 for supplying power to the peripheral circuits, and the fan motor 4. Is detected through the filter circuit 9 as a rotor magnetic pole position detection signal, and the actual rotational speed is recognized from the rotor magnetic pole position detection signal and compared with the rotational speed of the command input from the external circuit. Rotation speed setting circuit 11 for controlling the rotation speed by limiting the current
And a chopper circuit 5 for comparing the chopper reference signal output from the rotation speed setting circuit through the duty command circuit 10 with the triangular wave signal output from the triangular wave generation circuit 6 and outputting a chopper signal, and a rotation speed setting circuit. A drive circuit 2 for driving a power element (switching element) 3 by a drive signal and a chopper signal output from 11, and a fan motor drive including a current limiting circuit 7 and an overcurrent protection circuit 8 as a protection circuit for the power element 3. It is composed of a control circuit, a compressor 15 and a compressor drive control circuit 14.

After the fan motor start command is input from the external circuit, when the fan motor is rotated by the air blown to the fan, a counter electromotive force is generated from the motor and the filter circuit 9 is generated.
Is input to the position detection circuit 12, and a rotor magnetic pole position detection signal is output. This rotor magnetic pole position detection signal is
The rotation speed setting circuit 11 detects for a predetermined time, for example,
Detection is performed for 0.4 seconds, and the processing shown in FIG. 1 is performed. The process of FIG. 1 will be described with reference to FIGS. 4 to 7.

FIG. 4 is a position detection circuit diagram, FIG. 5 is a diagram showing waveforms of A, D, E, and F portions of the position detection circuit 12, and FIG. 6 is an upper arm of the power element (switching element) 3 ( Q1, Q2,
Q3), lower arm (Q4, Q5, Q6) and position detection circuit 1
It is a figure which shows the drive timing of 2 output parts (VA, VB, VC).

The rotor magnetic pole position detection signal having an electrical angle of 180 ° width such as the voltage of the F portion shown in FIG. 5 is used as one phase, and the rotor magnetic pole position detection signals for the other three phases are similarly created. , A rotor magnetic pole position signal pattern (not shown) in the rotation direction (forward rotation) during fan motor operation which is set in advance in the rotation speed setting circuit 11 is checked, and the rotor position detection signal (shown in FIG. 6) VA, VB, VC) A signal such as a G portion of a signal such as a rising edge and a falling edge having an electrical angle of 60 ° is counted how many times it is detected within a predetermined time (0.4 seconds). Determine the rotation speed of the rotor. If the rotor speed is 94 min to ¹ or more and it matches the rotor magnetic pole position detection signal pattern during normal rotation,
Performs startup processing during normal rotation.

The acceleration processing is to output a drive signal according to the rotor magnetic pole position based on the output of the position detection circuit from the state where the fan motor is rotating at a predetermined rotation number at the time of the synchronous start. ON / OFF the element
At the same time, the current is gradually increased to accelerate the rotation speed of the rotor to a predetermined rotation speed. Further, the speed control is a control for maintaining a target number of revolutions, and when the disturbance is applied such as when the wind is blown or when the ventilation resistance passing through the heat exchanger is changed, The number of revolutions is determined by the position detection signal, and the current or voltage is controlled to increase or decrease so as to reach the target number of revolutions. Here, a process of detecting a fan lock from the detected rotation speed and sending a signal to the compressor drive control circuit 14 is also included.

When the rotation speed setting circuit 11 determines that the rotation is normal, the brushless operation is performed without performing the positioning and the low frequency synchronous operation, which are the usual start methods, and the start processing is terminated and continued. Brushless operation is performed by controlling the rotation speed according to the load. At the time of switching to the brushless operation, when the power element (switching element) 3 is turned on and current is supplied to the motor winding, the terminal voltage of the motor winding of the portion A shown in FIG. Since the D section voltage and the E section voltage of the position detection circuit 12 that detects the magnetic pole position reach the power supply 12V of the comparator used in the position detection circuit 12, the E section voltage and the D section voltage cannot be compared, The rotor position detection signal output from the position detection circuit 12 is disturbed. When a current is applied to the motor winding in response to this disturbed rotor position detection signal,
Since a rotating magnetic field that acts on the rotor in the direction opposite to the rotation direction is generated with respect to the rotor position, or a rotating magnetic field that acts on the torque is generated in the rotating direction, the rotation of the rotor is not stable and the position of the rotor relative to the rotating magnetic field is Step out, rotation stops.

Therefore, when the rotation speed setting circuit 11 determines that the rotation is normal, the rotation speed setting circuit 11 outputs a drive signal for driving the drive circuit 2 in accordance with the rotor magnetic pole position detection signal. In addition, the chopper circuit 5 uses the initial value of the chopper reference signal obtained by converting the digital signal output from the rotation speed setting circuit 11 into an analog signal by the duty command circuit as a voltage lower than the triangular wave signal output from the triangular wave generation circuit. The chopper reference signal is increased as the commutation of the chopper signal output from the stopped state is commutated, the duty of the chopper signal is controlled, and the drive circuit 2 and the power element (switching element) 3 are driven by this chopper signal. To limit the current that flows to the motor. As a result, at the time of switching to the normal rotation brushless operation, the upper arms (Q1, Q2, Q3) of the power element (switching element) 3 are driven and the lower arm (Q
4, Q5, Q6) are stopped because the chopper signal is not output, a voltage is applied to the motor winding, and only the base current of the position detection circuit 12 and the power element (switching element) 3 flows as a current.

The stop state of the lower arms (Q4, Q5, Q6) is held for a period of time during which the voltages of the D and E portions of the position detection circuit 12 shown in FIG. A chopper signal is output from the time when the partial voltages can be compared, and the lower arm (Q4, Q5, Q6) of the power element (switching element) 3 is driven to supply a current to the motor winding. As a result, the switching to the brushless operation at the time of forward rotation is stably performed, and the motor can be smoothly accelerated to the commanded rotation speed.

Next, the reverse rotation will be described with reference to FIG. 1 in the same manner as the normal rotation. When the rotor magnetic pole position detection signal pattern during normal rotation does not match the rotor magnetic pole position detection signal input from the position detection circuit 12 to the rotation speed setting circuit 11, or when the rotation speed is 94 min to less than ¹ The rotor magnetic pole position detection signal pattern in the rotation direction during motor operation and the reverse rotation direction is collated, and it is determined from the 60 ° width signal whether or not the number of rotations of the rotor is 43 min to ¹ or more. When this number of revolutions is 43 min to ¹ or more and coincides with the rotor magnetic pole position detection signal pattern in the reverse rotation direction, the starting process (reverse braking, rotor stop, synchronous start) during reverse rotation is performed. .

Next, the stoppage will be described with reference to FIG. The pattern of the rotor magnetic pole position detection signal during reverse rotation,
When the rotor magnetic pole position detection signals input from the position detection circuit 12 to the rotation speed setting circuit 11 do not match, or when the rotation speed is 43 min to less than ¹ , current is applied to the two phases of the motor winding shown in FIG. After the center of the magnetic field and the center of the rotating magnetic field are positioned and then synchronously started, the brushless operation is switched to end the start-up process, and then the brushless operation according to the load is performed.

Next, a method of detecting the locked state of the fan motor in one embodiment of the present invention will be described. FIG. 1 is a control block diagram showing an embodiment of the present invention.

In general, a sensorless brushless motor cannot detect the magnetic pole position of the rotor because the rotor magnetic pole does not induce a voltage in the stator winding when the rotor is stopped. Therefore, the locked state of the motor cannot be detected before starting the motor. A feature of the present invention is that the rotation speed of the fan motor is detected by the output signal of the position detection circuit while driving the fan motor for the air conditioner.

When the fan motor is in the locked state, the output signal of the position detection circuit corresponding to the normal rotation speed cannot be obtained during the speed control process, so that the rotation speed setting circuit 11 causes the rotation of the fan motor. It is determined that a failure has occurred in the fan motor and the fan motor is locked, and a fan lock signal is output to the compressor drive control circuit 14.

FIG. 2 is a control block diagram for explaining a method of detecting the locked state of the fan motor during the speed control process, which is one of the control block diagrams showing the embodiment of the present invention.
Since the rotation speed of the rotor can be known from the number of times the position detection signal input from the position detection circuit 12 receives the magnetic pole position detection signal within a predetermined time, the fan lock is determined based on this rotation speed.

In the present embodiment, the detected rotation speed is different from the target rotation speed, and if the state of 150 min to ¹ or less continues for 3 minutes, it is judged to be the fan lock state, the rotation of the fan motor is stopped, and the compressor is driven. A signal for stopping the driving of the compressor is output to the control circuit 14. The compressor drive control circuit 14 stops driving the compressor 15 when the communication signal of the fan lock signal is input. Further, when the fan motor is locked, the compressor drive control circuit may reduce the rotation speed of the compressor by the output fan motor lock signal to mitigate the temperature rise of the electric parts and prevent the destruction of the electric parts. .

According to the embodiment, the means for detecting the lock of the fan motor is provided by the output signal of the position detection circuit, and the communication means for notifying the compressor drive control circuit 14 of the detection of the fan lock is provided. By stopping the operation, there is an effect that it is possible to prevent thermal destruction due to a temperature rise of the electric component. Further, since the communication means is provided between the compressor drive control circuit for driving the compressor and the control circuit of the brushless fan motor, it is possible to control the compressor and the fan motor independently. The control circuit has an effect that the starting operation of the fan motor can be repeated until the locked state of the fan motor is released.

Further, since the means for stopping the driving of the compressor when the brushless fan motor is locked is provided, it is possible to prevent an increase in the pressure of the compressor, which has the effect of improving the reliability of the compressor. Further, since the means for detecting the lock state of the fan motor is provided by the output signal of the position detection circuit 12, parts such as a hall sensor for detecting the lock of the motor are unnecessary in the fan motor, and the fan motor is inexpensive. It has the effect of producing.

Although the embodiment has described the means for detecting the locked state of the outdoor fan motor of the air conditioner,
It goes without saying that the means for detecting the locked state of the rotor in other brushless motors can be similarly performed.

[0042]

As described above, according to the present invention, air having a fan using a brushless motor provided with a rotor having a permanent magnet in the motor case and a stator is provided. In the harmony machine, by detecting the fan lock and stopping the compressor, there is an effect that the thermal destruction due to the temperature rise of the electric parts can be prevented.

[Brief description of drawings]

FIG. 1 is a control block diagram showing an embodiment of the present invention.

FIG. 2 is a control block diagram showing details of fan motor lock detection in FIG.

FIG. 3 is a circuit block diagram showing an embodiment of the present invention.

FIG. 4 is a position detection circuit diagram showing an embodiment of the present invention.

FIG. 5 is a waveform chart of each part of the position detection circuit according to the embodiment of the present invention.

FIG. 6 is a drive timing chart of a power element showing an embodiment of the present invention.

FIG. 7 shows an embodiment of the present invention in normal time (when rotation is stopped)
Startup pattern diagram

FIG. 8 is a circuit diagram showing a basic example of a drive circuit for a conventional commutatorless motor.

FIG. 9 is a voltage waveform diagram induced in a prior art stator winding.

FIG. 10 is a circuit diagram showing an example in which FIG. 8 is improved.

11 is a voltage waveform induced in the stator winding shown in FIG.

FIG. 12 is a circuit diagram showing an example of a drive circuit of a conventional non-rectifier motor.

FIG. 13 is a positional relationship diagram of a prior art stator winding and a rotor.

FIG. 14 is a positional relationship diagram of a prior art stator winding and a rotor.

FIG. 15 is a positional relationship diagram of a prior art stator winding and a rotor.

FIG. 16 is a positional relationship diagram of a prior art stator winding and a rotor.

[Explanation of symbols]

1 ... Rectifier circuit, 2 ... Drive circuit, 3 ... Power element (switching element), 4 ... Fan motor, 5 ... Chopper circuit, 6 ... Triangular wave generation circuit, 7 ... Current limiting circuit, 8 ... Overcurrent protection circuit, 9 ... Filter circuit, 10 ... Duty command circuit, 11 ... Rotation speed setting circuit, 12 ... Position detection circuit, 1
3 ... Internal power supply, 14 ... Compressor drive control circuit, 15 ... Compressor

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Toru Inoue, Toru Inoue, Ohira-cho, Shimotsuga-gun, Tochigi 800 Tomita, Ltd. Living Equipment Division, Hitachi, Ltd. No. 2 within Hitachi Tochigi Electronics Co., Ltd.

Claims (4)

[Claims] 1. An air conditioner comprising a compressor, a heat exchanger, a fan for blowing air to the heat exchanger, and a brushless fan motor for driving the fan, and a rotor in the brushless fan motor. A position detection circuit for detecting the rotor magnetic pole position by using the winding voltage induced in the stator winding by the rotation of the magnetic pole, and the stator according to the rotor magnetic pole position detected by this position detection circuit. An air conditioner comprising: a plurality of switching elements that conduct and block a current flowing through a winding; and a means for detecting a locked state of the brushless fan motor. 2. An air conditioner comprising a compressor, a heat exchanger, a fan that blows air to the heat exchanger, and a brushless fan motor that drives the fan, and a rotor in the brushless fan motor. A position detection circuit for detecting the rotor magnetic pole position by using the winding voltage induced in the stator winding by the rotation of the magnetic pole, and the stator according to the rotor magnetic pole position detected by this position detection circuit. A plurality of switching elements for conducting and blocking a current flowing through the winding, means for detecting a locked state of the brushless fan motor, a compressor drive control circuit for driving a compressor, and a lock for the brushless fan motor. Means for communicating the status to the compressor drive control circuit. 3. The air conditioner according to claim 1, wherein the means for detecting the locked state of the brushless fan motor detects the locked state of the fan motor based on the output signal of the position detection circuit. 4. The air conditioner according to claim 2, wherein the compressor drive control circuit includes means for stopping drive of the compressor when the brushless motor is locked.