JP3465732B2 - Control method of brushless motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation control technology of a brushless motor used for a motor of a compressor of an air conditioner, and more particularly, to a variable width of an applied voltage of the brushless motor depending on the number of rotations, which is optimum. The present invention relates to a control method for a brushless motor that enables various rotation speed control.

[0002]

2. Description of the Related Art To control the rotation of a brushless motor,
For example, the control device shown in FIG. 4 is required. In this figure, this control device includes an AC power supply 1 and an AC / DC converter 2
The power source obtained by converting into DC is supplied to the inverter unit 3 for switching, and this switched power source is applied to the armature winding of the brushless motor (for example, three-phase motor) 4.

The position detection circuit 5 compares, for example, armature winding voltages (induced voltages) R, S, T of the brushless motor 4 with a reference voltage, and outputs a position detection signal of the comparison result to a control circuit (microcomputer) 6 Output to.

The control circuit 6 outputs the drive signal of the inverter section 3 to the drive circuit 7 in order to detect the position of the rotor by the input position detection signal and to switch the energization of the armature winding current in a predetermined manner. The drive circuit 7 includes a transistor U, which forms an upper arm of the inverter unit 3, based on the drive signal.
V, W and transistors X, Y, which form the lower arm,
Drive Z. Further, in the PWM control method, the control circuit 6 outputs a drive signal including a predetermined chopping signal to the drive circuit 7.

In this way, the position of the rotor is detected based on the position detection signal, and the energization of each armature winding of the brushless motor 4 is switched based on this position detection to control the rotation of the brushless motor 4. To do.

Further, the ON / OFF ratio (ON time, OFF time) of the chopping signal is changed, that is, the applied voltage of the brushless motor 4 is changed to control the rotation speed of the brushless motor 4, for example, the rotation of the brushless motor 4. When increasing the number, the applied voltage is increased, and conversely, when decreasing the rotational speed, the applied voltage is decreased.

[0007]

However, in the above brushless motor control method, the timing of changing the rotation speed of the brushless motor 4 (the timing of changing the applied voltage) is set at a predetermined time asynchronous with the position detection timing. There is a drawback in that the responsiveness of the rotation speed control is poor and the accuracy of the rotation speed control cannot be improved.

That is, the rotation speed of the brushless motor 4 is detected based on the position detection, and this position detection information is not reflected in the variable applied voltage. In particular, since the position detection interval becomes larger in a region where the rotation speed is lower, the responsiveness of the rotation speed control is deteriorated, that is, the accuracy of the rotation speed control is deteriorated, and as a result, the rotation speed is increased or decreased.

Further, when it is used for a motor of a compressor of an air conditioner, for example, it is not preferable that the response of the rotation speed control is deteriorated. That is, it is preferable to keep the increase and decrease of the rotation speed constant in order to quickly create a comfortable environment in the room.

The present invention has been made in view of the above problems, and an object thereof is to appropriately change an applied voltage when controlling the rotation speed of a brushless motor, improve the responsiveness of the rotation speed control, and improve the rotation speed control. It is an object of the present invention to provide a brushless motor control method capable of improving accuracy.

[0011]

In order to achieve the above object, the present invention switches a DC power supply to apply it to an armature winding of a brushless motor while detecting the position of a rotor of the brushless motor, A method for controlling a brushless motor, which switches energization of an armature winding current of the brushless motor on the basis of the position detection, and controls rotation speed by varying an applied voltage of the brushless motor,
When controlling the rotation speed of the brushless motor, the minimum variable width of the voltage applied to the brushless motor is changed according to the current rotation speed.

In the brushless motor control method according to the present invention, when controlling the rotation speed of the brushless motor, the voltage applied to the brushless motor is changed at the position detection timing or at the timing synchronized with the position detection timing. The minimum variable width of the applied voltage is changed according to the current rotation speed.

In the brushless motor control method of the present invention, the minimum variable width for varying the voltage applied to the brushless motor corresponding to the rotation speed of the brushless motor is stored in the storage means as a table, When controlling the rotation speed of the brushless motor, the minimum variable width of the voltage applied to the brushless motor is changed by referring to the table.

According to the brushless motor control method of the present invention, the minimum variable width for varying the voltage applied to the brushless motor in correspondence with the rotation speed of the brushless motor is stored as a table in the storage means. When controlling the rotation speed of the brushless motor, the voltage applied to the brushless motor is changed at the timing of the position detection or at the timing synchronized with the timing of the position detection,
The minimum variable width of the applied voltage is changed by referring to the table.

In this case, the minimum variable width may be increased in a region where the rotation speed of the brushless motor is low, and the minimum variable width may be decreased in a region where the rotation speed of the brushless motor is high.

Further, it is preferable that the brushless motor is applied to a compressor motor of an air conditioner.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to FIGS. Note that FIG.
In FIG. 4, those parts which are the same as those corresponding parts in FIG. 4 are designated by the same reference numerals, and a duplicate description will be omitted.

1, in addition to the function of the control circuit 6 shown in FIG. 4, this brushless motor control device applies the brushless motor 4 according to the current rotation speed when controlling the rotation speed of the brushless motor 4. Control circuit (microcomputer) 10 for changing the minimum variable voltage width (variable width) of voltage
Is equipped with. Further, the control circuit 10 varies the applied voltage at the position detection timing (or the timing synchronized with the position detection) when controlling the rotation speed of the brushless motor 4.

Next, the operation of the brushless motor control device will be described with reference to the time charts of FIGS. 2 and 3. First, the control circuit 10 includes the position detection circuit 5 as in the conventional case.
The position of the rotor is detected on the basis of the position detection signal from and the energization of the armature winding current of the brushless motor 4 is switched based on this position detection.

In the position detection operation mode, when the current rotational speed calculated based on the position detection when varying the applied voltage to control the rotational speed is low, the variable voltage width of the applied voltage is large. The value (for example, 3V) is set, and the applied voltage is changed at the position detection timing (see FIG. 2). The control circuit 10 varies the applied voltage by changing the on / off of the chopping signal of the output drive signal (including the chopping signal) according to the variable voltage width.

When the current rotational speed is high, the rotational speed may already be near the target rotational speed. Therefore, the variable voltage width of the applied voltage is set to a small value (for example, 1 V), and the applied voltage is set to the position. It is performed at the detection timing (see FIG. 2).

As described above, the variable voltage width is increased in the low speed range so that the rate of increase and decrease of the speed of rotation is larger than that of the prior art. Therefore, even if the position detection interval is long, the speed of rotation is increased and decreased. That is, the rotation speed can be quickly set to the target rotation speed, the responsiveness of the rotation speed control can be improved, and the accuracy of the rotation speed control can be improved.

In the high speed range, the variable voltage width is reduced,
For example, since the same value as the conventional value is used, even if the position detection interval is short, the increase / decrease rate of the rotation speed does not become too large, the target rotation speed is easily maintained, and the accuracy of the rotation speed control is improved. be able to.

Further, since the timing for changing the variable voltage width is the position detection timing or the timing synchronized with the same position detection timing, the position detection can be reflected in the variable voltage width variable, and the responsiveness of the rotational speed control can be improved. Will be improved.

By the way, as a control method of the brushless motor of the present invention, the minimum variable voltage width (variable width) for varying the voltage applied to the brushless motor 4 in accordance with the rotation speed of the brushless motor 4 is preset. The ROM (storage means) 10a of the control circuit 10 may be stored in the table format shown in Table 1 below. The ROM 10a is the control circuit 1
It may be externally attached to 0.

[0026]

[Table 1] As is clear from Table 1, the lower the rotation speed, the larger the variable voltage width of the voltage applied to the brushless motor 4, and the higher the rotation speed, the smaller the variable voltage width of the voltage applied to the brushless motor 4. . The data in Table 1 is an example when applied to a compressor motor of an air conditioner.

As described above, since the variable voltage width can be increased in the low speed range of the brushless motor 4 and the variable voltage width can be changed for each rotation speed, the load characteristics and the like are known in advance. It is effective when applied in
Moreover, the rotation speed control can be performed more finely, the responsiveness of the rotation speed control can be further improved, and the accuracy of the rotation speed control can be improved.

Further, if the variable voltage width is changed at the position detection timing or at a timing synchronized with the position detection timing, the position detection can be reflected in the variable variable voltage width, that is, the responsiveness of the rotational speed control can be improved. Therefore, the accuracy of the rotation speed control can be improved.

In the above-described embodiment, since the rotation speed of the brushless motor 4 is in the wavy line range as shown by the wavy line in FIG. 3, the applied voltage is increased or decreased (variable) when the rotation speed is out of the wavy line range. Add the voltage range,
Alternatively, the applied voltage may be maintained (the variable voltage width may be set to zero) when the rotation speed is within the wavy line range.

Then, the rotation speed of the brushless motor 4 can be raised or lowered at a constant level, which is particularly preferable for controlling the rotation speed of the compressor motor of the air conditioner, and an appropriate rotation speed for making the room a comfortable environment. It becomes possible to control.

As a method of changing the rotation speed of the brushless motor 4, the method of changing the duty ratio of the chopping signal to change the applied voltage has been described. However, another method is used to change the applied voltage to change the rotation speed. It can also be applied to the method.

[0032]

As described above, according to the first aspect of the brushless motor control method of the present invention, the minimum variable width (variable voltage width) of the voltage applied to the brushless motor is changed according to the current rotational speed. As a result, the response of the rotation speed control can be improved, and the accuracy of the rotation speed control can be improved.

According to the second aspect of the invention, the voltage applied to the brushless motor is varied at the position detection timing or at the timing synchronized with the position detection timing.
In addition, since the minimum variable width of the applied voltage is changed according to the current rotation speed, it is possible to further improve the responsiveness of the rotation speed control and further improve the accuracy of the rotation speed control. .

According to the invention of claim 3, the minimum variable width for varying the voltage applied to the brushless motor corresponding to the rotation speed of the brushless motor is stored as a table in the storage means, and this table is referred to. Since the variable width of the applied voltage of the brushless motor is changed, it can be applied when it is known in advance, the rotation speed control can be performed more finely, and the responsiveness of the rotation speed control can be improved. There is an effect that the accuracy of the rotation speed control can be improved.

According to the invention of claim 4, the voltage applied to the brushless motor is varied at the timing of position detection or at the timing synchronized with the timing of position detection.
Moreover, since the variable width of the applied voltage is changed with reference to the table of claim 3, in addition to the effect of claim 3, the response of the rotation speed control can be further improved.
There is an effect that the accuracy of the rotation speed control can be further improved.

According to the invention of claim 5, claims 1, 2,
In addition to 3 or 4, the variable width is increased in a region where the rotation speed of the brushless motor is low, and the variable width is decreased in a region where the rotation speed of the brushless motor is high. The target speed can be quickly set at a low speed, the control response can be improved, the accuracy of the speed control can be improved, and the target speed can be set at a high speed. This has the effect of easily maintaining the rotation speed.

According to the invention of claim 6, claims 1, 2,
Since the brushless motor of 3, 4 or 5 is applied to the motor of the compressor of the air conditioner, the air having a constant rotation speed of the brushless motor can be obtained by the effect of claim 1, 2, 3, 4 or 5. There is an effect that it is possible to perform preferable rotation control for the harmony machine, that is, it is possible to quickly make the room a comfortable environment.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a control device to which an embodiment of the present invention is applied and to which a method of controlling a brushless motor is applied.

FIG. 2 is a schematic time chart diagram for explaining the operation of the control device shown in FIG.

FIG. 3 is a schematic time chart diagram for explaining the operation of the control device shown in FIG.

FIG. 4 is a schematic block diagram of a conventional brushless motor control device.

[Explanation of symbols]

1 AC power supply 2 AC / DC converter 3 Inverter section 4 brushless motor 5 Position detection circuit 6,10 Control circuit (microcomputer) 10a ROM (storage means)

Claims (6)

(57) [Claims] 1. A DC power supply is switched and applied to an armature winding of a brushless motor, while the position of a rotor of the brushless motor is detected, and the armature winding of the brushless motor is detected based on the detected position. A method for controlling a brushless motor, which switches the energization of a current and controls the rotation speed by varying the applied voltage of the brushless motor,
A method of controlling a brushless motor, wherein a minimum variable width of a voltage applied to the brushless motor is controlled according to a current rotational speed when controlling the rotational speed of the brushless motor. 2. A DC power supply is switched to apply it to the armature winding of the brushless motor, while detecting the position of the rotor of the brushless motor, and the armature winding of the brushless motor is based on the detected position. A method for controlling a brushless motor, which switches the energization of a current and controls the rotation speed by varying the applied voltage of the brushless motor,
When controlling the rotation speed of the brushless motor, the voltage applied to the brushless motor is changed at the position detection timing or the timing synchronized with the position detection timing, and the minimum variable width of the applied voltage is changed to the current rotation. A control method for a brushless motor, characterized in that it is changed according to the number. 3. A brushless motor armature winding is detected by switching a DC power supply and applying the same to an armature winding of the brushless motor, and detecting the position of a rotor of the brushless motor. A method for controlling a brushless motor, which switches the energization of a current and controls the rotation speed by varying the applied voltage of the brushless motor,
The minimum variable width for varying the voltage applied to the brushless motor corresponding to the rotation speed of the brushless motor is stored in the storage means as a table, and the brushless motor is controlled when controlling the rotation speed of the brushless motor. A method of controlling a brushless motor, characterized in that the minimum variable width of the voltage applied to is changed with reference to the table. 4. A brushless motor armature winding is detected by switching a DC power supply and applying the same to the armature winding of the brushless motor, and the position of the rotor of the brushless motor is detected. A method for controlling a brushless motor, which switches the energization of a current and controls the rotation speed by varying the applied voltage of the brushless motor,
The minimum variable width for varying the voltage applied to the brushless motor corresponding to the rotation speed of the brushless motor is stored as a table in the storage means, and the position detection is performed when controlling the rotation speed of the brushless motor. The voltage to be applied to the brushless motor is changed at the same timing as the above timing or the same position detection timing, and the minimum variable width of the applied voltage is changed by referring to the table. Brushless motor control method. 5. The minimum variable width is increased in a region where the rotation speed of the brushless motor is low, and the minimum variable width is decreased in a region where the rotation speed of the brushless motor is high. , 3 or 4, the brushless motor control method. 6. The method of controlling a brushless motor according to claim 1, 2, 3, 4, or 5, wherein the brushless motor is a compressor motor of an air conditioner.