JP2789920B2 - Motor drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driving apparatus using an AC motor as a motor and using a Hall element to detect the rotation speed of the AC motor.

[0002]

2. Description of the Related Art For example, when a DC motor is used to drive a fan of a home air conditioner, speed control can be easily performed, but since there is no DC power supply in the home,
It is necessary to convert an AC power supply to a DC power supply, which causes a problem that the air conditioner is expensive and large.

Accordingly, an AC motor is used as a motor for driving a fan of a home air conditioner. A conventional example of a motor drive device for an air conditioner using an AC motor is disclosed in JP-A-61-164485.

This conventional example uses a sensor magnet and a Hall element as speed detecting means when detecting the speed of an AC motor and controlling a predetermined number of revolutions, and outputs the output according to the number of revolutions of the motor. The speed of the motor is controlled by detecting a signal from the Hall element and processing the signal.

[0005]

In general, a sensor magnet for detecting a speed is formed in a disk shape by alternately arranging a plurality of magnets of N and S poles, and is attached to a rotating shaft of a rotor. Therefore, if the motor stops when the valley of the magnetic flux of the sensor magnet coincides with the detection unit of the Hall element, the Hall element is affected by the leakage magnetic flux of the coil end at the time of restart, and the motor rotates at a certain speed. There is a problem that it is erroneously determined to be.

Therefore, there is a conventional example in which the positions of the Hall element and the sensor magnet are shifted to a position not affected by the leakage magnetic flux. 4 and 5 show such a conventional example. FIG. 4 is a sectional view of a main part of the AC motor M, and FIG. 5 is a view seen from the direction A in FIG.

A sensor magnet 4 is attached to an end of the rotating shaft 1 of the rotor 2 via a bush 3.
It rotates with it.

As shown in FIG. 5, the sensor magnet 4 is composed of a plurality of N-pole and S-pole permanent magnets arranged alternately, and is formed in a substantially disk shape. This sensor magnet 4
A printed circuit board 6 on which a Hall IC 5 composed of a Hall element is mounted so as to face the device.

A stator 7 is disposed on the outer periphery of the rotor 2, and a coil 8 is wound around the stator 7.
In the figure, X indicates the leakage magnetic flux of the coil end 9, and the sensor magnet 4 indicated by a dashed line indicates a conventional mounting position. In this case, as described above, when the valley of the magnetic flux of the sensor magnet 4 (the black circle in FIG. 5) matches the position of the Hall IC 5, the motor stops and the Hall IC 5 leaks from the coil end 9 when restarting. Under the influence of the magnetic flux X, it is erroneously determined that the motor is rotating at a predetermined rotation speed.

Therefore, the sensor magnet 4 is disposed at the position shown by the solid line in FIG. However, even in such a case, it may not be applicable to all motors, and if the motor is started at a low speed by phase control driving, the AC magnetic flux is detected and the rotational speed is erroneously detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide a motor drive device capable of performing a start-up compensation for an AC motor and obtaining a reliable startability. is there.

[0012]

Means for Solving the Problems] Therefore drive motor of the present invention, a Hall element, a detecting means for detecting a rotational speed of <br/> AC motor M by means of such a sensor magnet, detected by the detection means Let's bring the speed closer to the target speed
The drive device for a motor and a control circuit for cormorants control, drives the or in the motor reaches the initial rotational speed set in advance when starting the AC motor M, it reaches the initial rotational speed
Sometimes, a startup compensating means is provided for shifting to rotation speed control by the control circuit , and the initial rotation speed is
By the AC magnetic flux of the AC power applied to the AC motor M
It is characterized in that it is set to be lower than the induced false detection speed .

[0013]

According to the above-described motor driving device, the AC motor
When starting the motor M, the motor M
Drives and rotates by the control circuit when the initial rotation speed is reached
Numerical control, for example phase control, is performed. And at this time
The initial rotation speed is determined by the AC power applied to the AC motor M.
Smaller than the false detection rotation speed induced by AC magnetic flux
It is said that the startup compensation operation has been performed because it has been set.
This means that no misdetection has occurred and normal rotation speed detection is performed.
After that, it is controlled
Normal rotation speed control by a circuit may be performed.
As a result, according to the above-described motor driving device, the
Malfunction due to false detection of rotation speed due to AC magnetic flux
Generation can be eliminated, and the reliable startability of AC motor M can be obtained.
It is.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a specific embodiment of a motor driving device according to the present invention will be described in detail with reference to the drawings. Note that the basic configuration for detecting the AC motor M and the rotation speed of the AC motor M is the same as that of the conventional example, and the present invention compensates for the activation of the AC motor by software.

FIG. 2 is a diagram showing the overall structure of the AC motor M.
A cross-flow fan 10 is connected to the rotating shaft 1, and a sensor magnet 4 is attached to the rotating shaft 1. A Hall IC 5 is provided to face the sensor magnet 4. The sensor magnet 4 and the Hall IC 5 constitute detection means for detecting the number of revolutions of the AC motor M. Although the sensor magnet 4 and the Hall IC 5 are separately provided in FIG. 2, they are illustrated for convenience, and are actually built in the AC motor M.

A microcomputer 11 constituting a control circuit capable of arbitrarily setting the number of revolutions of the AC motor M is mounted on a printed circuit board 12, and a control relay 13 for controlling the phase of the AC motor M is mounted on the printed circuit board 12. I have. Then, a rotation speed signal is input from the Hall IC 5 to the microcomputer 11, and a control signal is output from the microcomputer 11 to the control relay 13 so that the microcomputer 11 controls the phase of the control relay 13 so that the rotation speed becomes the set rotation speed.

FIG. 3 shows an AC voltage waveform applied from the control relay 13 to the coil of the AC motor M. FIG. 3A shows a voltage waveform at a high speed, and FIG. 3B shows a voltage waveform at a low speed. ing. The phase angle increases at lower speeds,
This phase control is controlled by the microcomputer 11.

Next, the control of the starting compensation of the AC motor M, which is the gist of the present invention, will be described with reference to FIG. FIG. 1
RVNOW shown in (1) and (2) show the determined value of the number of revolutions, and RVS shows the measured value of the number of revolutions. The number of revolutions is always measured irrespective of operation or stop. The rotation speed fixed value is the rotation speed after the start compensation.

Now, when the control is started, if the rotation speed of the AC motor M is 200 rotations (rpm) or less,
Judge that the motor is stopped and start the motor, that is,
Wait until the AC power is applied. And start the motor
Then, the rotation speed of the motor is increased. And if the measured value of the rotational speed is still 200 rotates (rpm) or less, gradually increases the voltage applied to position phase angle is forced to AC motor M by 1 step smaller. Note that the motor
It is assumed that the start-up compensation has been completed if
To the next process.

The measured value of the motor rotation speed is 200 rpm
When the speed reaches between 300 and 300 rpm, the initial rotation speed is reached.
Then, the measured value of the rotation speed of the motor at that time is determined as the actual rotation speed (RVNOW = RVS). This completes the motor start-up compensation control, and shifts to control toward the originally set rotational speed , for example, phase control . The startup compensation means for performing startup compensation is constituted by the microcomputer 11.

According to the motor driving device,
When starting the AC motor M, the motor
The motor M is driven, and the control circuit
Rotation speed control, for example, phase control is performed. And this
When the initial rotation speed is equal to the AC applied to the AC motor M,
Than the false detection rotation speed induced by the AC magnetic flux of the power supply
Since the start compensation operation was performed because it was set small
This means that no erroneous detection has occurred and a normal
It means that the exit is taking place, and then
Means that the normal rotation speed control by the control circuit
Become. As a result, according to the motor drive device,
Sometimes, due to the false detection of rotation speed due to AC magnetic flux
Occurrence of malfunctions can be eliminated, and reliable startability of AC motor M
Is obtained. In the above embodiment, the initial rotation speed is 2
00 rpm (or between 200 rpm and 300 rpm)
This is the AC power applied to the AC motor
Times lower than the false detection rotation induced by the AC magnetic flux
Any number of rotations can be selected. For example
The erroneous detection rotation speed is the commercial frequency (50 Hz / 60 Hz).
Function, and the sensor magnet 4 makes one rotation as shown in FIG.
False detection if the number of pulses to be determined is 3 pulses / rotation
The number of rotations is 50 (Hz / sec) × 60 (sec / min) ÷ 3 (Hz
/ Rotation) = 1000 rotations / minute (or 1200 rotations / minute)
And set the initial frequency in the range described above.
That is, it can be surely confirmed that there is no false detection.
You. By controlling in this manner, the motor can be started from a very low speed, so that the air volume change by the fan 10 becomes smooth, and it is possible to start from a very low speed regardless of the motor structure. Further, since the engine can be started from an extremely low speed, the engine does not need to be started from a high rotation speed, so that there is no overshoot of the rotation speed and the driving sound does not feel uncomfortable.

[0022]

The motor driving apparatus according to the present invention comprises a detecting means for detecting the rotational speed of the AC motor, and a control circuit capable of setting the AC motor to an arbitrary rotational speed in response to a signal from the detecting means. After confirming that there is no erroneous detection when starting the AC motor ,
Since the startup compensating means for shifting to the rotation speed control by the control circuit is provided, there is an effect that the AC motor can be started smoothly and reliably.

[Brief description of the drawings]

FIG. 1 is a flowchart of an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of the same.

FIG. 3 (a) is a waveform diagram of a current voltage applied to an AC motor at the time of high speed according to the first embodiment. (B) is a waveform diagram of a current voltage applied to the AC motor at the time of low speed in the above.

FIG. 4 is a sectional view of a main part of the AC motor.

FIG. 5 is a diagram viewed from a direction A in FIG. 4;

[Explanation of symbols]

 M AC motor

Claims (1)

(57) [Claims] 1. A detecting means for detecting the number of revolutions of an AC motor (M) by means such as a Hall element, a sensor magnet, etc., and the number of revolutions detected by the detecting means is brought close to a target number of revolutions.
The drive device for a motor and a control circuit for so that control, drives the initial <br/> until in motor becomes the rotation speed previously set when starting the AC motor (M), the initial rotational speed
When the speed reaches
Made by the start compensating means is provided for, further the initial rotational speed
Is the AC of the AC power applied to the AC motor (M).
Set lower than the false detection speed induced by magnetic flux.
Motor driving device, characterized in that are.