JPH05236770A - Motor driver - Google Patents

Abstract

PURPOSE:To realize positive starting performance by providing a start compensating means for forcibly starting an AC motor until a preset number of revolution is reached thereby avoiding erroneous detection of the number of revolution under low speed. CONSTITUTION:A microcomputer 11 and a control relay 13 for controlling the phase of an AC motor M are mounted on a printed board 12. A number of rotation signal is fed from a Hall IC 5 to the microcomputer 11 which then delivers a control signal to the control relay 13 and controls the phase of the AC motor M through the control relay 13 such that a set number of rotation is achieved. If measured number of rotation is lower than 200 rpm, a decision is made that the detection result of the Hall element 5 is within the range of erroneous detection and then the phase angle is decreased by one step thus forcibly increasing the voltage to be applied onto the AC motor M. When the measured number of rotation reaches between 200 rpm and 300 rpm, the measured value is employed as an actual number of revolution in the speed control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive apparatus which uses an AC motor as a motor and uses a hall element to detect the rotational speed of the AC motor.

[0002]

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

Therefore, an AC motor is used as a motor for driving a fan of a domestic air conditioner. Japanese Patent Application Laid-Open No. 61-164485 is a conventional example of a drive device for a motor of an air conditioner using an AC motor.

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 rotations, and outputs according to the number of rotations of the motor. The speed of the motor is controlled by detecting the signal from the Hall element that operates and processing this signal.

[0005]

Generally, a sensor magnet for speed detection has a plurality of N-pole and S-pole magnets alternately arranged to form a disk shape and is attached to a rotating shaft of a rotor. Therefore, when the motor stops at the point where the valley of the magnetic flux of the sensor magnet and the detection part of the hall element match, the hall element is affected by the leakage magnetic flux at the coil end when restarting, and the motor rotates at a certain number of revolutions. There is a problem of misjudging that the

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

A sensor magnet 4 is attached to an end portion of the rotating shaft 1 of the rotor 2 via a bush 3, and the rotating shaft 1
It is designed to rotate 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 disc shape. This sensor magnet 4
A printed circuit board 6 on which a Hall IC 5 composed of a Hall element is mounted is arranged so as to face the.

A stator 7 is arranged 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 shown by the alternate long and short dash line indicates the 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) and the position of the Hall IC 5 match, the Hall IC 5 leaks to the coil end 9 when the motor is stopped and restarted. 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 arranged 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 phase-controlled to start at a low speed, the AC magnetic flux is detected and the rotational speed is erroneously detected.

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 which performs start compensation of an AC motor to obtain reliable startability. is there.

[0012]

Therefore, the motor drive device of the present invention detects the number of revolutions of the AC motor M, and receives a signal from the detector to set the AC motor M to an arbitrary number of revolutions. A motor drive device including a control circuit that can be set is characterized in that start-up compensating means for forcibly starting the AC motor M until it reaches a predetermined rotation speed is provided at the time of starting the AC motor M.

[0013]

In the motor drive device, the start compensating means forcibly starts the AC motor M until it reaches a predetermined rotational speed when the AC motor M is started, thereby reliably starting the AC motor M. be able to.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of the motor drive device of the present invention will be described in detail with reference to the drawings. The basic configuration for detecting the rotational speed of the AC motor M and the AC motor M is the same as that of the conventional example, and the present invention is configured to compensate the starting of the AC motor by software.

FIG. 2 shows the overall configuration of the AC motor M.
A cross-flow fan 10 is connected to the rotary shaft 1 and a sensor magnet 4 is attached to the rotary shaft 1. A Hall IC 5 is arranged so as to face the sensor magnet 4. The sensor magnet 4 and the Hall IC 5 constitute a detecting means for detecting the rotation speed of the AC motor M. Although the sensor magnet 4 and the Hall IC 5 are separately provided in FIG. 2, the sensor magnet 4 and the Hall IC 5 are illustrated for convenience, and are actually incorporated in the AC motor M.

A microcomputer 11 forming a control circuit capable of arbitrarily setting the rotation speed 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. There is. 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 is set.

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

Next, the control of the starting compensation of the AC motor M, which is the subject matter of the present invention, will be described with reference to FIG. Figure 1
RVNOW shown in (1) indicates a rotational speed fixed value, and RVS indicates a rotational speed measured value, and the rotational speed is always measured regardless of whether it is running or stopped. Further, the rotation speed fixed value is the rotation speed after the start compensation.

If the number of revolutions of the AC motor M is 200 revolutions (rpm) or less when the operation is started, it is determined that the motor is stopped, the motor is started, and the number of revolutions of the motor is increased. To go. If the measured value of the rotation speed is still 200 rpm (rpm) or less, the Hall IC5
Since it is within the range of erroneous detection, the phase angle is reduced by one step and the voltage applied to AC motor M is forcibly increased.

When the measured value of the number of rotations of the motor reaches between 200 rpm and 300 rpm, it is considered that the detection of the Hall IC 5 is out of the range of the false detection, and the measured value of the number of rotations of the motor at that time is taken as the actual number of rotations. Judge (RVNOW =
RVS). This completes the motor start compensation control and shifts to the control of the originally set rotation speed. It should be noted that the start compensation means for performing start compensation is configured by the microcomputer 11.

By controlling in this manner, the motor can be started from an ultra-low speed, so that the change in the air volume by the fan 10 becomes smooth, and the motor can be started from an ultra-low speed regardless of the motor structure. Furthermore, since the engine can be started from an ultra-low speed, starting from a high rotation is not necessary, there is no overshoot of the rotation speed, and the discomfort of the driving noise is eliminated.

[0022]

The motor drive device of the present invention comprises the detection means for detecting the rotational speed of the AC motor, and the control circuit for receiving the signal from the detection means and setting the AC motor at an arbitrary rotational speed. In the motor drive device provided, a start compensating means for forcibly starting the motor at the time of starting the AC motor until a predetermined number of rotations is provided is provided. By forcibly starting the motor until a predetermined number of rotations set in advance, the AC motor can be smoothly and reliably started.

[Brief description of drawings]

FIG. 1 is a flow chart of an embodiment of the present invention.

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

FIG. 3A is a waveform diagram of a current voltage applied to the AC motor at the same high speed as above. (B) is a waveform diagram of the current voltage applied to the AC motor at the same low speed.

FIG. 4 is a cross-sectional view of a main part of an AC motor.

5 is a view seen from the direction A in FIG. 4. FIG.

[Explanation of symbols]

 M AC motor

Claims (1)

[Claims] 1. A motor comprising a detection means for detecting the rotation speed of the AC motor (M) and a control circuit capable of receiving a signal from the detection means and setting the AC motor (M) at an arbitrary rotation speed. 2. The motor drive device according to claim 1, further comprising a start compensating means for forcibly starting the AC motor (M) when the AC motor (M) is started up to a predetermined rotational speed.