JP2003319690A - Brushless motor drive for air conditioner fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor drive for an air conditioner fan capable of preventing demagnetization due to damping or stopping even if the fan is rotated by an external factor at a low atmospheric temperature. <P>SOLUTION: When there are provided an inverter circuit 3 in which a plurality of switching elements are connected to a three-phase bridge and which supplies an electric current to the stator winding of the brushless motor drive for the air conditioner fan; a Hall element 2 for detecting the magnetic pole position of a rotor of the brushless motor; a phase switching element on either a positive voltage side or a negative voltage side of the inverter circuit; the other two phase switching elements are energized by being synchronized with an output signal of the Hall element before the startup of the brushless motor; and a control means 10 for damping and stopping the rotor is provided by PWM-energizing at least one or the other of the positive voltage side and the negative voltage side, a temperature detection means S2 for detecting the atmospheric temperature of the brushless motor is also provided. The control means lowers the duty ratio of the PWM energization as the atmospheric temperature detected by the temperature detection means becomes low. <P>COPYRIGHT: (C)2004,JPO

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 for an air conditioner fan, which supplies a current to a stator winding to brake and stop a rotor before at least the start of the brushless motor.

[0002]

2. Description of the Related Art Brushless motors have been widely used as motors for driving fans of air conditioners.
The outdoor fan rotates when there is wind, and its rotation direction and speed are not uniform. If the outdoor fan is rotating at the start of operation of the air conditioner, it must be braked, stopped, and positioned before being started.

A brushless motor requires a detector for detecting the magnetic pole position of its rotor. For braking, stopping, and positioning of the outdoor fan, the direction and rotation speed of the outdoor fan are detected based on the output of this detector, and the current of the stator winding is controlled accordingly. However, since three Hall elements are used as the detector, complicated control is inevitable, which is one of the causes of the cost increase. In addition, a direct current was passed through the stator windings during braking, stopping, and positioning. However, this method causes demagnetization of the permanent magnets that form the rotor, and destruction of the drive circuit that passes current through the stator windings. There was a possibility that an excessive current would flow.

Therefore, for example, Japanese Patent Laid-Open No. 2000-1255.
In Japanese Patent Publication No. 84, in order to drive a brushless motor,
Using an inverter circuit in which a plurality of switching elements are connected in a three-phase bridge connection, one of the positive voltage side and negative voltage side switching elements of the inverter circuit is PWM-energized before starting the brushless motor,
Either of the other two switching elements of the other phases are set to P
It is disclosed that the WM is energized to brake, stop, and position the rotor.

[0005]

The permanent magnets forming the rotor magnetic poles of brushless motors include ferrite magnets and rare earth magnets. Of these, rare earth magnets are expensive, so they are used as fan motors in air conditioners. Ferrite magnets are often used. Generally, a ferrite magnet has poor low temperature characteristics, and is easily demagnetized when a large current is applied to the stator at low temperatures. Especially, for outdoor fans, it is unavoidable to start at low ambient temperature (0 ° C or less) in winter. Demagnetization may occur when the normal startup control is executed in such a state.

The one described in Japanese Patent Laid-Open No. 2000-125584 uses a PWM switching element for one phase on either the positive voltage side or the negative voltage side of the inverter circuit.
The duty ratio of the PWM energization was fixed when energizing and energizing the rotor by applying PWM to the remaining two phase switching elements to apply braking to the rotor. This P
The duty ratio of WM energization is set to a value at which it is affected by the limiting current at normal temperature. However, when PWM energization is performed at the same duty ratio as at room temperature in the above-described low temperature state, the winding resistance of the stator becomes low. Therefore, there is a problem in that demagnetization is likely to occur in combination with the fact that the current becomes large and the low temperature characteristics of the ferrite magnet are poor.

The present invention has been made in view of the above circumstances, and its purpose is to prevent demagnetization due to braking and stopping even when the fan is rotating due to external factors when the ambient temperature is low. Another object of the present invention is to provide a drive device for a brushless motor for a fan of an air conditioner, which can be prevented.

[0008]

The invention according to claim 1 is
An inverter circuit that supplies a current to the stator winding of a brushless motor for a fan of an air conditioner, a hall element that detects the magnetic pole position of the rotor of the brushless motor, and a start of the brushless motor, in which a plurality of switching elements are connected in a three-phase bridge Before, in synchronization with the output signal of the Hall element,
At least one of the positive voltage side and the negative voltage side is energized while energizing the switching element of one phase on either the positive voltage side or the negative voltage side of the inverter circuit and the remaining two phase switching elements on the other side. In a drive unit for a brushless motor for a fan of an air conditioner, which includes a control unit that energizes PWM to brake and stop the rotor, the control unit includes a temperature detection unit that detects an ambient temperature of the brushless motor. A drive device for a brushless motor for a fan of an air conditioner, characterized in that the duty ratio of PWM energization is reduced as the ambient temperature detected by the device decreases.

According to a second aspect of the present invention, in the fan brushless motor driving device for an air conditioner according to the first aspect, when the brushless motor is for an outdoor fan, the temperature detecting means is the temperature of the outdoor heat exchanger. When the brushless motor is for an indoor fan, the temperature detecting means is used instead of the temperature detecting means of the indoor heat exchanger.

According to a third aspect of the present invention, a plurality of switching elements are connected in a three-phase bridge and an inverter circuit for supplying a current to a stator winding of a brushless motor for an air conditioner fan, and a magnetic pole position of a rotor of the brushless motor. Hall element to detect the, and before the start of the brushless motor,
In synchronization with the output signal of the Hall element, while energizing the switching element of one phase on either the positive voltage side or the negative voltage side of the inverter circuit and the switching element of the other two phases on the other side, In a drive device for a brushless motor for a fan of an air conditioner, which comprises a control means for PWM-energizing at least one of the positive voltage side and the negative voltage side to brake and stop the rotor, the control means further comprises:
The air conditioner is characterized in that braking is applied to the rotor even at the end of the slow frost mode operation, and the duty ratio of PWM energization at the end of the slow frost mode operation is reduced as compared with the braking before starting. Drive device for brushless motor for fans.

According to a fourth aspect of the present invention, a plurality of switching elements are connected in a three-phase bridge, and an inverter circuit that supplies a current to a stator winding of a brushless motor for an air conditioner fan and a magnetic pole position of a rotor of the brushless motor. Hall element to detect the, and before the start of the brushless motor,
In synchronization with the output signal of the Hall element, while energizing the switching element of one phase on either the positive voltage side or the negative voltage side of the inverter circuit and the switching element of the other two phases on the other side, In a drive unit for a brushless motor for a fan of an air conditioner, which includes a control unit that applies PWM to at least one of a positive voltage side and a negative voltage side to brake and stop the rotor, a current detection unit that detects a current in a stator winding. A drive device for a brushless motor for a fan of an air conditioner, characterized in that the control means increases the duty ratio of PWM energization as much as possible within a range not exceeding a predetermined current limit value.

According to a fifth aspect of the present invention, in the fan brushless motor drive device for an air conditioner according to the fourth aspect, there is provided temperature detection means for detecting the ambient temperature of the brushless motor, and a predetermined current limit value is set. The lower the ambient temperature detected by the temperature detecting means, the lower the ambient temperature is set.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail based on the preferred embodiments shown in the drawings. FIG. 1 is a block circuit diagram showing a schematic configuration of a control unit of an air conditioner to which the present invention is applied together with a refrigeration cycle system. In the figure, the discharge side of the compressor 31 is connected to one end of the indoor heat exchanger 33 through one switching path of the four-way valve 32. The other end of the indoor heat exchanger 33, via the expansion valve 34,
It is connected to one end of the outdoor heat exchanger 35. The other end of the outdoor heat exchanger 35 is connected to the suction side of the compressor 31 through the other switching path of the four-way valve 32. And
These form a well-known refrigeration cycle, and by circulating the refrigerant in the direction of arrow A, operation is performed in a heating mode in which the indoor heat exchanger 33 functions as a condenser and the outdoor heat exchanger 35 functions as an evaporator.

Here, an outdoor fan 1F driven by the outdoor fan motor 1 is provided in order to promote heat exchange of the outdoor heat exchanger 35. The outdoor fan motor 1 is a brushless motor having a rotor in which magnetic poles are formed by ferrite magnets, and a Hall IC 2 is mounted inside to detect the magnetic pole position of the rotor. Also,
An inverter circuit 3 for supplying three-phase power to the stator winding of the outdoor fan motor 1 is provided. The inverter circuit 3 converts alternating current of a single-phase alternating current power supply 11 into direct current, and further the direct current is a pseudo waveform of PWM waveform. It is converted into phase alternating current and supplied to the outdoor fan motor 1. Further, each output signal of the current detection circuit 5 for detecting the current of the outdoor fan motor 1, the temperature sensor S1 for detecting the temperature of the outdoor heat exchanger 35, and the temperature sensor S2 for detecting the outside air temperature, which is accompanied by the current transformer 5A. On the basis of,
An outdoor control device 10 that controls the inverter circuit 3, the four-way valve 32, and the expansion valve 34 is provided.

On the other hand, an indoor fan 6F is provided which is driven by the indoor fan motor 6 to promote heat exchange of the indoor heat exchanger 33. This indoor fan motor 6
Also uses a brushless motor having a rotor in which magnetic poles are formed by ferrite magnets, and includes an inverter circuit 7 for controlling the speed thereof. In this case, the Hall IC for detecting the magnetic pole position of the indoor fan motor 6 is omitted for simplification of the drawing. The inverter circuit 7 converts the AC of the single-phase AC power supply 11 into DC, and further converts the DC into P
It is converted into a pseudo three-phase AC having a WM waveform and supplied to the indoor fan motor 6. Further, a temperature sensor S3 for detecting the temperature of the indoor heat exchanger 33 and a temperature sensor S for detecting the indoor temperature.
The indoor control device 20 controls the inverter circuit 7 based on each detected value of 4. The outdoor control device 10 and the indoor control device 20 are connected by a signal line that exchanges information with each other.

Next, the operation of the air conditioner shown in FIG. 1 will be described. Setting signals such as an operation mode and a room temperature are transmitted to the indoor control device 20 from a remote control device (not shown). At this time, when the operation mode is heating, the outdoor control device 10 energizes the four-way valve 32 to form a path for circulating the refrigerant in the arrow A direction. As a result, the indoor heat exchanger 3
A heating operation in which 3 functions as a condenser and the outdoor heat exchanger 35 functions as an evaporator becomes possible. Further, while the indoor control device 20 controls the inverter circuit 7, the outdoor control device 10 controls the inverter circuit 3 to supply PWM currents to the outdoor fan motor 1 and the indoor fan motor 6, respectively. In this case, before the outdoor control device 10 rotates the outdoor fan motor 1, if the outdoor fan 1F is rotating, control of braking, stopping, and positioning of the outdoor fan motor 1 is performed based on the output signal of the Hall IC 2. To do. The details of this braking / stopping control will be described later. In addition,
Since the positioning is described in Japanese Patent Laid-Open No. 2000-125584, its description is omitted.

On the other hand, the indoor control device 20 calculates the number of revolutions of the compressor 31 according to the difference between the room temperature set by the remote control device and the room temperature detected by the temperature sensor S4, and the calculated result is calculated as the outdoor control device 10. Send to. The outdoor control device 10 controls the rotation speed of the compressor 31 in accordance with this rotation speed and also controls the rotation speed of the outdoor fan motor 1. Further, the outdoor control device 10 controls the opening degree of the expansion valve 34 according to the temperature of the outdoor heat exchanger 35 detected by the temperature sensor S1 and the like, and shuts off the energization of the four-way valve 32 to operate in the slow frost mode. To do The indoor control device 20 performs control for preventing overheating of the indoor heat exchanger 33 based on the temperature detection signal of the temperature sensor S3. Since these controls have been proposed and are well known, their description will be omitted. .

FIG. 2 is a circuit diagram showing a configuration of a first embodiment of a brushless motor driving device for a fan of an air conditioner according to the present invention. In the figure, an outdoor fan motor (hereinafter, abbreviated as a brushless motor including drawings) 1
U-phase, V-phase, and W-phase stator windings are star-connected,
Further, a Hall IC 2 is provided on the stator.
Of these, the external connection conductors of the stator windings U, V, W are connected to the inverter circuit 3, and the current supply and detection signal conductors of the Hall IC 2 are connected to the control device 10.

In the inverter circuit 3, transistors Fu, Fv, Fw, Fx, Fy and Fz which are FETs (Field Effect Transistors) are connected as a switching element in a three-phase bridge connection. That is, the transistors Fu and F
A series connection circuit of x, a series connection circuit of transistors Fv and Fy, and a series connection circuit of transistors Fw and Fz are connected in parallel, and one end thereof is connected to the positive electrode of a DC power supply (DC280V) not shown via the switch 4. And the other end is connected to the negative electrode of the DC power supply. These transistors Fu, Fv, Fw, Fx, Fy and Fz are respectively connected to diodes Du, Dv, Dw, Dx, Dy and Dz for free circulation in antiparallel.

Further, the transistors Fu, Fv, Fw, F
x, Fy, to the gates of the Fz, the drive circuit _B 1 made of a _{photo-coupler, B 2, B 3, B} 4, B 5, B 6 is connected.

The operating power for these drive circuits is supplied.
For the primary side, the transformer connected to the single-phase AC power supply 11
Connected to the transformer 12 and the secondary side of the transformer 12 in series.
Diode D₀₁And smoothing capacitor C₀₁And
It has a half-wave rectifier circuit. And the capacitor C
₀₁The drive circuit B whose positive electrode is the negative voltage side of the DC power supply_Four，
B₅, B₆Capacitor C
₀₁The negative electrode of the drive circuit B_Four, B ₅, B₆On the other end of
Are connected and connected, the transistors Fx, Fy, Fz
It is connected to each source (negative voltage side). In addition, direct current
Drive circuit B on the positive voltage side of the source₁, B_Two, B_ThreeTo each
Capacitor C that stores drive power₀₂, C₀₃, C ₀₄But
It is connected in parallel, and its positive electrode is a diode D for preventing backflow.
₀₂, D₀₃, D_{0 Four}Through the resistor R for current limiting
It is connected to one end. The other end of this resistor R is a half-wave rectification circuit.
Capacitor C that constitutes the path₀₁Is connected to the positive electrode of
It Also, the capacitor C₀₂, C₀₃, C₀₄The negative electrode of
Connected to each source of transistors Fu, Fv, Fw
There is.

On the other hand, the external connection conductors of the stator windings U, V, W of the brushless motor 1 are connected to the interconnection points of the transistors Fu and Fx, Fv and Fy, Fw and Fz, respectively. The signal output conductor of the Hall IC 2 provided in the brushless motor 1 is connected to an MCU (microcomputer unit) 100 that constitutes the control device 10, and a control signal G output from the MCU 100 is connected.
₁ , G ₂ , G ₃ , G ₄ , G ₅ , G ₆ are configured to be added to the drive circuits B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B ₆ , respectively. Further, a current transformer 5A is provided in the DC current path of the inverter circuit 3, and the current detection circuit 5 is configured to apply a current detection signal to the outdoor control device 10.

The operation of the present embodiment configured as described above will be described below. Transistors Fu, Fv, F
w, Fx, Fy, and Fz are connected to the DC input terminals of the inverter circuit 3 in which the three-phase bridge connection is made, and D of the DC power supply not shown
A voltage of C280V is applied. Here, the transistors Fu, Fv, and Fw are referred to as switching elements on the positive voltage side of the inverter circuit, and the transistors Fx, Fy, and Fz are referred to as switching elements on the negative voltage side of the inverter circuit. AC power supply 11 is AC100V, transformer 1
2 lowers this voltage to AC5V, for example. The stepped-down AC is rectified and smoothed by a half-wave rectifier circuit including a diode D ₀₁ and a capacitor C ₀₁ , and the obtained DC voltage is a transistor F as a switching element on the negative voltage side.
a drive circuit B ₄ , which drives x, Fy, and Fz, respectively.
It is applied to both ends of B ₅ and B ₆ .

On the other hand, a drive circuit B for driving the transistors Fu, Fv, Fw as switching elements on the positive voltage side.
Capacitors C connected in parallel to ₁ , B ₂ , and B ₃ , respectively
₀₂ , C ₀₃ , and C ₀₄ are connected to the capacitor C via the resistor R when the negative voltage side switching element is turned on.
Sequential charging (charge-up) by the voltage across ₀₁
To be done. Before the start of the inverter circuit 3, the capacitors C ₀₂ , C ₀₃ , and C ₀₄ are all charged by turning on the transistors Fx, Fy, and Fz all at once. As a result, the transistors Fu, Fv, Fw, F
x, Fy, Fz drive circuits B ₁ , B ₂ , B ₃ , B ₄ , B
₅ and B ₆ can be operated. A charging circuit for a capacitor connected in parallel to these drive circuits is known as a charge pump system, and is described in, for example, Japanese Patent Application Laid-Open No. 9-37587, so a detailed description of its operation will be omitted.
At least during normal operation, the capacitors C ₀₂ , C ₀₃ , C are set according to the energization pattern for each switching element.
₀₄ is charged.

Next, before starting the air conditioner, the outdoor fan that has been rotated by the wind must be stopped and positioned. Therefore, the brushless motor 1 needs to be braked and stopped.

In this case, the MCU 100 controls the control signals G ₁ ,
By adding G ₂ , G ₃ , G ₄ , G ₅ , G ₆ to the drive circuits B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B ₆ , respectively, as shown in FIG. All of the U-phase transistor Fu and the W-phase transistor Fw on the voltage side and the transistor Fy on the negative voltage side are PWM-energized, or one of the positive voltage side and the negative voltage-side is continuously energized and the other is PWM-energized. When energized, a PWM current is passed through the stator windings U, V, W to generate a magnetic field in a predetermined direction to stop the rotor. In this specification, this is referred to as braking by a DC excitation energization pattern. Since the PWM current flows in the braking by the DC excitation energization pattern, there is an effect that the demagnetization of the permanent magnet is suppressed without imposing an excessive load on the drive circuit and the motor.

By the way, when a ferrite magnet is used for the rotor of the brushless motor 1, the temperature characteristic of the ferrite magnet at low temperature is poor, and when a large current is applied to the stator at low temperature, demagnetization is likely to occur. In the present embodiment, when the ambient temperature of the brushless motor 1 exceeds 0 ° C., for example, the duty ratio of PWM energization is increased to quickly brake and stop the temperature of 0 ° C.
At the following low temperatures, the duty ratio of PWM energization is reduced to prevent the ferrite magnet from being demagnetized and to be braked and stopped.

To explain this, FIG. 4 is a diagram showing the relationship between the duty ratio of PWM energization and the current flowing in the stator winding, that is, the motor current, with the ambient temperature as a parameter. Here, when the ambient temperature of the brushless motor 1 is higher than 0 ° C., for example, 5 ° C., the motor current increases linearly as the duty ratio of PWM energization increases as shown by the characteristic line P. On the other hand, when the ambient temperature of the brushless motor 1 is lower than 0 ° C., for example, −3 ° C., the motor current increases as the winding resistance decreases.
It has a characteristic that it linearly increases as the duty ratio of WM energization increases, and that the characteristic line P is translated to the left side. That is, even if the duty ratio of PWM energization is reduced, the same amount of current flows. As is apparent from this, when the ambient temperature of the brushless motor 1 is −3 ° C., when PWM energization is performed with the same duty ratio as when the ambient temperature is 5 ° C., an excessive current flows and the ferrite magnet is driven. There is a risk of demagnetization.

Therefore, in this embodiment, when the ambient temperature T of the brushless motor 1 exceeds 0 ° C., the current limit value I
When the duty ratio of PWM energization is set to D1 so that the current IA is equal to or less than LA, and the ambient temperature T of the brushless motor 1 is lower than 0 ° C., the current limit value ILB (<IL
A) The duty ratio of PWM energization is set to D2 (<D1) so as to suppress the current IB below.

FIG. 5 is a waveform diagram showing the relationship of the above-mentioned DC excitation energization. In the figure, (a) shows the U-phase transistors Fu and W on the positive voltage side when the ambient temperature T exceeds 0.degree. When the braking / stopping control in which the transistor Fw is PWM-energized and the V-phase transistor Fy on the negative voltage side is continuously energized is performed over the period P, the duty ratio D1 = W1 /
In the figure, (b) shows that the U-phase transistor Fu on the positive voltage side and the W-phase transistor Fw are PWMed when the ambient temperature T is lower than 0 ° C. When the braking and stop control for energizing and continuously energizing the V-phase transistor Fy on the negative voltage side is performed for the period P, it is shown that the DC excitation energizing is performed with the duty ratio D2 = W2 / Q. Here, there is a relationship of W1> W2. Therefore, with the relationship of D1> D2, PWM energization is performed at a duty ratio D1 of flowing a current IA equal to or less than the allowable current ILA in a range where the atmospheric temperature exceeds 0 ° C. In the range where the temperature is lower than 0 ° C., PWM energization is performed with the duty ratio D2 that suppresses the current IB to the allowable current ILB or less.

Thus, according to the first embodiment, even when the fan is rotating due to an external factor when the ambient temperature is low, demagnetization due to braking and stopping can be prevented in advance.

In the above embodiment, when the ambient temperature T of the brushless motor 1 is lower than 0.degree.
Although the duty ratio of energization was reduced, the ambient temperature immediately after the defrosting mode operation performed during the heating mode operation is considered to be 0 ° C. or lower. Therefore, if the outdoor fan 1F is still rotating at this point, it is necessary to carry out the DC excitation energization with a reduced duty ratio of the PWM energization.

FIG. 6 is a flow chart showing a concrete processing procedure of the MCU 100 corresponding to the braking / stopping control including the start-up time and the defrosting return time. Here, first, in step 111, it is determined whether or not the operation is started. If it is determined that the operation is started, in step 112, the ambient temperature T
Is 0 ° C or more, and when 0 ° C is exceeded, the duty ratio of PWM energization is set to D1 in step 113, and the start control including braking and stop control is executed in step 114. Then, the processing from step 111 onward is repeated. If it is determined in step 111 that the operation has not started, it is determined in step 115 whether the defrosting operation has ended, that is, whether defrosting has recovered, and if defrosting has recovered, PWM energization is performed in step 116. The duty ratio is set to D2, and the start control including the braking and stop control is executed in step 114. In step 112, the ambient temperature T is 0 ° C.
Also when it is determined that the value does not exceed step 116, step 116
Then, the duty ratio of PWM energization is set to D2, and at step 114, start-up control including braking and stop control is executed.
When it is determined in step 115 that defrosting has not been recovered, other normal control is executed in step 117 and the process returns to step 111.

By the processing of the MCU 100 shown in FIG. 6, when the ambient temperature at the time of startup exceeds 0 ° C., DC excitation is performed with the duty ratio of PWM energization being D1 and the ambient temperature at the startup is 0 ° C. or less. PW when and after defrost recovery
Direct current excitation is performed with the duty ratio of M conduction being D2 (<D2), whereby demagnetization due to braking and stopping can be prevented in advance.

In the first embodiment, the ambient temperature T
It was determined whether the duty ratio was D1 or D2 depending on whether or not the temperature exceeded 0 ° C., and these duty ratios were fixed values set with a margin below the allowable value of the current. In other words, it is a value that guarantees that overcurrent will not occur even when the ambient temperature drops considerably. Therefore, control of braking and stopping tends to be prolonged. As one method for shortening the control time for the braking and stopping, it is conceivable to set the duty ratio close to the current allowable value ILA or ILB in FIG.

FIG. 7 is a flow chart in which the MCU 100 is provided with its function as a second embodiment based on such an idea. In this case, first, in step 121, it is determined whether or not the operation is started, and when it is determined that the operation is started, in step 122, it is determined whether or not the atmospheric temperature T exceeds 0 ° C, and 0 ° C is set. When it exceeds, the current limit value Is is set to I1 (large) in step 123. On the other hand, when it is determined in step 121 that the operation has not started, it is determined in step 124 whether the defrosting operation has ended, that is, whether or not defrosting has been restored.
At 5, the current limit value Is is set to I2 (small). Also when it is determined in step 122 that the ambient temperature T does not exceed 0 ° C., the current limit value Is is set to I in step 125.
Set to 2 (small).

Next, in step 127, the duty ratio d corresponding to the current smaller than the two current limit values is set to execute braking and stop control, and the current I at that time is detected in step 128. . Next, at step 129, it is judged whether or not the detected current value I exceeds the electric limit value Is corresponding to each ambient temperature. Here, if the current detection value I does not exceed the current limit value Is, the duty ratio of PWM energization is increased by Δd in step 130, and conversely, the current detection value I exceeds the current limit value Is. If so, in step 131, the duty ratio of PWM energization is reduced by Δd, and braking and stop control are executed, respectively. Next, in step 132, it is determined whether or not the fan has stopped, that is, whether or not the braking / stopping control has been completed. If completed, the start control is started in step 133, and if not completed. The processing from step 128 onward is repeated. If it is determined in step 124 that defrosting has not been recovered, other normal control is executed in step 126, and the process returns to step 121.

Thus, also in the second embodiment in which the processing procedure of the MCU 100 is shown in FIG. 7, when the fan is rotating due to an external factor when the ambient temperature is low, as in the first embodiment. However, demagnetization due to braking and stopping can be prevented in advance, and DC excitation energization is performed at a current that is closest to the allowable current according to the ambient temperature, so the braking and stopping control time is shortened. be able to.

By the way, in the second embodiment,
Although the current limit value Is is set to two types depending on whether the ambient temperature exceeds 0 ° C., regardless of the ambient temperature,
It is also possible to set the current limit value Is and always flow a current slightly lower than the current limit value Is for direct current excitation.

In each of the above-described embodiments, the variation range of the ambient temperature is divided into two, such as whether the ambient temperature exceeds 0 ° C., but the variation range is further divided into the atmosphere. By reducing the duty ratio of the PWM energization as the temperature becomes lower, the braking / stopping control time can be minimized.

In each of the above-described embodiments, the outdoor fan motor in which the fan rotates when there is wind is controlled. However, in an air conditioner having a larger capacity than that for general household use, the indoor fan motor is activated at startup. May be rotating. When this indoor fan motor is a brushless motor, the same braking / stopping control as described above can be performed by executing the processing shown in FIG. 6 or 7. In addition,
In controlling the indoor fan motor, the defrosting recovery determination processing shown in step 115 of FIG. 6 and step 124 of FIG. 7 is unnecessary.

Furthermore, in each of the above embodiments, the U-phase transistor Fu and the W-phase transistor Fw on the positive voltage side of the inverter circuit 3 connected in a three-phase bridge are used.
Is energized by PWM, and the V-phase transistor Fy on the negative voltage side is energized continuously to perform DC excitation. However, even if all of these transistors are energized by PWM, or U
It is possible to perform the same DC excitation as described above by continuously energizing the phase-phase transistor Fu and the W-phase transistor Fw and PWM-energizing the V-phase transistor Fy. Further, it is also possible to change the combination of energized phases and perform the same DC excitation as described above.

Further, in each of the above embodiments, the temperature sensor S2 for detecting the ambient temperature of the fan to be braked or stopped is provided. However, when the brushless motor to be braked or stopped is for an outdoor fan, the outdoor It is also possible to substitute the temperature sensor of the heat exchanger and substitute the temperature sensor of the indoor heat exchanger when the brushless motor to be braked or stopped is for an indoor fan.

[0044]

As is apparent from the above description, according to the present invention, even when the fan is rotating due to an external factor when the ambient temperature is low, demagnetization due to braking and stopping can be prevented. It is possible to provide a drive device for a brushless motor for a fan of an air conditioner that can prevent the above.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of a control unit of an air conditioner to which the present invention is applied together with a refrigeration cycle system.

FIG. 2 is a circuit diagram showing the configuration of a first embodiment of a brushless motor drive device for a fan of an air conditioner according to the present invention.

FIG. 3 is an explanatory diagram of a DC excitation energization pattern for explaining the operation of the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a duty ratio of PWM energization and a motor current with an ambient temperature as a parameter in order to explain an operation of the first embodiment of the present invention.

FIG. 5 is a diagram showing energization waveforms for braking / stopping control in order to explain the operation of the first embodiment of the present invention.

FIG. 6 is a schematic diagram for explaining a first embodiment of the present invention.
The flowchart which showed the specific processing procedure of CU.

FIG. 7 is a schematic diagram for explaining a second embodiment of the present invention.
The flowchart which showed the specific processing procedure of CU.

[Explanation of symbols]

1 Outdoor fan motor (brushless motor) 2 Hall IC 3,7 Inverter circuit 4 Switch 5 Current detection circuit 6 Indoor fan motor 10 Outdoor control device 11 AC power supply 12 Transformer 31 Compressor 32 Four-way valve 33 Indoor heat exchanger 34 Expansion valve 35 Outdoor heat exchanger 100 MCU Fu, Fv, Fw, Fx, Fy, Fz Transistor (FET) B _{1 to} B ₆ Drive circuit C _{01 to} C ₀₄ Capacitor

Claims (5)

[Claims] 1. An inverter circuit for connecting a plurality of switching elements in a three-phase bridge connection to supply a current to a stator winding of a brushless motor for a fan of an air conditioner, and a Hall element for detecting a magnetic pole position of a rotor of the brushless motor. Before starting the brushless motor, in synchronization with the output signal of the Hall element, one of the switching elements of one phase on the positive voltage side or the negative voltage side of the inverter circuit and the remaining of the other one A drive device for a brushless motor for a fan of an air conditioner, comprising: a control unit that energizes two-phase switching elements and PWM energizes at least one of a positive voltage side and a negative voltage side to brake and stop the rotor. And a temperature detecting means for detecting an ambient temperature of the brushless motor, wherein the control means includes the temperature detecting means. A drive unit for a brushless motor for a fan of an air conditioner, characterized in that the duty ratio of PWM energization is reduced as the ambient temperature detected by the stage decreases. 2. When the brushless motor is for an outdoor fan, the temperature detecting means substitutes for the temperature detecting means of an outdoor heat exchanger, and when the brushless motor is for an indoor fan, the temperature detecting means is for indoor use. The drive device for the brushless motor for a fan of an air conditioner according to claim 1, wherein the temperature detecting means of the heat exchanger is substituted. 3. An inverter circuit for supplying a current to a stator winding of a brushless motor for a fan of an air conditioner, and a Hall element for detecting a magnetic pole position of a rotor of the brushless motor, wherein a plurality of switching elements are connected in a three-phase bridge. Before starting the brushless motor, in synchronization with the output signal of the Hall element, one of the switching elements of one phase on the positive voltage side or the negative voltage side of the inverter circuit and the remaining of the other one A drive device for a brushless motor for a fan of an air conditioner, comprising: a control unit that energizes two-phase switching elements and PWM energizes at least one of a positive voltage side and a negative voltage side to brake and stop the rotor. The control means further applies braking to the rotor even at the end of the slow frost mode operation, and A drive device for a brushless motor for a fan of an air conditioner, characterized in that the duty ratio of PWM energization at the end of the slow frost mode operation is reduced as compared with braking. 4. An inverter circuit for connecting a plurality of switching elements in a three-phase bridge connection to supply a current to a stator winding of a brushless motor for a fan of an air conditioner, and a Hall element for detecting a magnetic pole position of a rotor of the brushless motor. Before starting the brushless motor, in synchronization with the output signal of the Hall element, one of the switching elements of one phase on the positive voltage side or the negative voltage side of the inverter circuit and the remaining of the other one A drive device for a brushless motor for a fan of an air conditioner, comprising: a control unit that energizes two-phase switching elements and PWM energizes at least one of a positive voltage side and a negative voltage side to brake and stop the rotor. A current detection means for detecting the current of the stator winding, and the control means does not exceed a predetermined current limit value. A brushless motor driving device for a fan of an air conditioner, characterized in that the duty ratio of PWM energization is maximized within a range. 5. A temperature detecting means for detecting an ambient temperature of the brushless motor is provided, and the predetermined current limit value is set to be lower as the ambient temperature detected by the temperature detecting means becomes lower. Item 5. A brushless motor drive device for a fan of an air conditioner according to Item 4.