JPH0824409B2 - Motor control device - Google Patents

Description

The present invention relates to a motor control device that controls the rotation speed of a motor by adjusting a firing phase angle.

<Prior Art> Conventionally, in a device such as an air conditioner or a combustor, a motor control device has been used in which an AC voltage is applied to a motor that rotationally drives a fan rotor via a triac or the like. Then, the actual rotation speed of the motor is detected, and the ignition phase angle of the triac is changed based on the comparison result between the detected rotation speed and the target rotation speed, and the rotation speed of the motor is feedback-controlled by this. The constant speed rotation of the fan rotor is realized.

FIG. 5 is a partial cross-sectional view of a motor used in the above-described motor control device. The motor 11 has a drive shaft 14 and a fan rotor 12 mounted on it. Reference numeral 17 is a rotor fixed to the drive shaft. 19 is a field surrounding the rotor 17, and 18 is a field winding. Further, as shown in FIG. 6, a rotating magnet plate 15 having N poles and S poles alternately arranged is attached to the drive shaft 14, and the magnetic field generated by the rotating magnet plate 15 is slightly separated from the rotating magnet plate 15. A Hall element 13 for detecting is arranged.

In such a motor, the number of revolutions of the motor is detected by detecting the alternating magnetic field by the Hall element 13 and measuring the frequency of the alternating magnetic field.

Then, when the rotation speed of the motor detected by the hall element 13 is smaller than the target rotation speed No, the ignition phase angle of the AC voltage is decreased to increase the rotation speed, and when it is larger than No, the AC The rotation speed was kept constant by increasing the ignition phase angle of the voltage and decreasing the rotation speed.

On the other hand, in the case where the motor is locked due to a load abnormality in the above motor, the rotation speed of the motor detected by the hall element 13 is zero and the ignition phase angle is expected to prevent the seizure. A protective device is known in which the power supply is shut off when it is determined that it is smaller than the ignition phase angle set corresponding to the maximum load (Japanese Patent Laid-Open No. 63-217919).
(See the official gazette).

<Problems to be Solved by the Invention> According to the protection device of the above publication, the lock of the motor can be detected, and after the detection, the power of the motor can be stopped without using a fuse or the like. , There are the following problems.

That is, when the rotation of the motor is stopped, the positional relationship between the Hall element 13 and the rotary magnet plate 15 is as shown in FIG. As shown in FIG. 7, it can be considered that the Hall element 13 is in a state in which a magnetic field is biased. In the former case, the output signal from the Hall element 13 does not appear in principle, and in the latter case, a DC component appears in the output signal from the Hall element 13. While the DC component is appearing, even if some noise component is added to the output signal, it will not be erroneously detected, but without the former output signal, if noise is received, it will be regarded as a signal and the motor will It will be judged that it is rotating. Here, noise is a magnetic field generated from the field magnet 19, for example. If the rotation speed of the magnetic field generated from the field 19 is small, voltage will be applied to the motor forever,
Burning will eventually occur.

The present invention has been made in view of the above problems,
It has a rotation speed detection means for detecting the rotation speed of the motor and a rotation control means for controlling the rotation speed of the motor by adjusting the ignition phase angle, and the rotation speed detected by the rotation speed detection means and the target rotation. In the controller of the motor that rotates the motor at a constant speed by changing the ignition phase angle based on the comparison result with the number of rotations, even if there is no abnormality in the detected rotation speed, the rotation abnormality of the motor can be reliably identified. An object of the present invention is to provide a motor control device capable of stopping the power supply of the motor.

<Means and Actions for Solving the Problems> The motor control device according to the first aspect of the present invention for achieving the above-mentioned object provides a range of ignition phase angles θmin to θmax expected within a normal load range. Storage means for storing the number of revolutions and shutting off the power applied to the motor when the ignition phase angle exceeds the range of the ignition phase angle stored in the storage means at the detected number of revolutions. And a means for stopping the power supply.

When the motor is normally rotating within the normal load range, the firing phase angle at that time is within the firing phase angle range stored in the storage means.

FIG. 1 is a graph in which the horizontal axis represents the firing phase angle θ and the vertical axis represents the rotation speed N, and the load is drawn as a parameter. The normal load range is the area between the curve A and the curve B. Indicated by.

However, if an abnormal load is applied to the rotation of the motor to cause a lock or the like, the detected ignition phase angle θ1 is detected even if the rotation of the motor is detected by the rotation speed detection means (the rotation speed is N1). , The range of phase angle corresponding to normal load θmin
Ends up to ~ max (point P on the graph).

In this case, the power supply is shut off by the power supply stopping means even when the rotation of the motor is detected.

In the motor control device of the second invention for achieving the above object, the rotation control means can change the ignition phase angle, and the rotation control means changes the ignition phase angle. Even if the rotation speed detected by the rotation speed detection means is not increased, the power supply stopping means for cutting off the power supply to the motor is provided.

According to the above configuration, if the rotation control means changes the firing phase angle, the rotation speed increases or decreases if there is no abnormality in the rotation of the motor, but if there is abnormality in the rotation of the motor (for example, lock The rotation speed does not increase or decrease. Therefore, in this case, even when the rotation of the motor is detected, it is determined that there is an abnormality, and the power supply stopping means cuts off the power supply.

<Examples> Detailed description will be given below with reference to the accompanying drawings showing examples.

FIG. 2 is a block diagram showing the basic configuration of the motor control device of the embodiment. The AC voltage from the AC power supply 1 is applied to the motor 3 via the triac 2. The motor 3 is used, for example, for blowing air in an air purifier, and a fan rotor 4 is fixed to its rotation shaft 3a. A cylindrical rotating magnet plate 5 having S poles and N poles alternately arranged in the circumferential direction is fixed to the rotating shaft 3a, and the rotating magnet plate 5 is provided in the vicinity of the rotating magnet plate 5. Hall IC that is a rotation speed detection means that detects the magnetic field that forms
6 are located. When the rotating magnet plate 5 rotates as the motor 3 rotates, the magnetic field detected by the Hall IC 6 changes at a cycle corresponding to the rotation speed of the motor 3.

The output of the Hall IC 6 is given to the control circuit 7 which adjusts the voltage applied to the motor 3 by controlling the firing phase angle of the triac 2. The control circuit 7 is also supplied with a detection signal from a zero-cross detection circuit 8 that detects a zero-cross point of the output voltage of the AC power supply 1.

The control circuit 7 derives a control signal for conducting the triac 2 at a timing corresponding to the firing phase angle after the detection signal is given. Control circuit 7
By changing the firing phase angle of TRIAC 2,
The waveform of the voltage applied to the motor 3 can be changed, and thus the rotation speed of the motor 3 can be changed.
Therefore, the target rotation speed No is set in advance in the control circuit 7, and this target rotation speed No is compared with the actual rotation speed N of the motor 3 obtained from the output of the Hall IC 6,
If the firing phase angle of the triac 2 is controlled based on the comparison result, the motor 3 can be rotated at a constant speed at the target rotation speed.

A detailed configuration of the control circuit 7 according to the embodiment of the first invention will be described.

As shown in FIG. 2, the output signal of the Hall IC 6 is input to the rotation speed detection unit 71. This rotation speed detection unit 71 measures, for example, the time required to input a predetermined number of pulses,
The frequency of the output pulse of the Hall IC 6 is detected based on this time. The output of the rotation speed detection unit 71 is given to the abnormality detection unit 73. Further, the rotation speed control unit 72 gives the present ignition phase angle θ of the triac 2 to the abnormality detection unit 73. The abnormality detection unit 73 determines that the firing phase angle θ is the firing phase angle range θmi in the normal load range stored in the phase angle storage unit 75.
It is checked whether or not n to θmax is entered, and if not entered, a stop signal is sent to the power stop unit 74. Power stop unit 74
Sends a predetermined signal to the rotation speed control unit 72, which stops the driving of the triac 2.

FIG. 3 is a flow chart for explaining the operation of the motor control device of the present embodiment having the above-mentioned configuration.

The protection operation by the motor control device is performed by interruption every predetermined time after the motor is driven.

In step S1, the rotation speed N of the motor is detected, and in step S2, the ignition phase angle θ at the rotation speed N is θmin-
Check if it is within θmax. If it does not enter, it is judged to be abnormal in step S3 and stopped. At this time, a display may be given to inform the person. If yes, it is judged to be normal rotation and the state before interruption is returned.

Thereby, the abnormal rotation state of the motor can be eliminated early.

Next, a detailed configuration of the control circuit 7 according to the embodiment of the second invention will be described.

The control circuit 7 is different from the configuration of the first embodiment in the following points. That is, the rotation speed control unit 72 has a built-in timer circuit and has a function of changing the firing phase angle θ over the time counted by the timer under a predetermined condition. On the other hand, the abnormality detection unit 73 has a function of checking a change in the rotation speed.

FIG. 4 is a flow chart for explaining the operation of the motor control device of the present embodiment having the above-mentioned configuration.

The protection operation of this embodiment is also performed by interruption every predetermined time after driving the motor.

In step S10, the rotation speed N of the motor is detected. In step S11, it is checked whether or not the rotation speed N of the motor has reached the target rotation speed No. If not, the interruption is stopped.

When the target rotation speed No is reached, a rotation test of the motor is performed in step S12. That is, the firing phase angle θ is changed to a lower value, and it is checked in step S14 whether the rotation speed N changes. The observation of the change in the ignition phase angle θ is continued until the timer counts the time T unless the rotation speed N changes.

Note that the firing phase angle θ can be changed until it becomes smaller than θmin, which is the lower limit of the firing phase angle range θmin to θmax corresponding to a normal load, in order to detect a significant change in the rotation speed N. desirable. Further, it is desirable that the time T for changing the firing phase angle is shorter than the time at which the temperature of the coil may reach the upper limit temperature at which the insulation is compensated when the motor is locked.

If the rotation speed N changes during the time T, it is determined to be normal,
Returns to the state before the interrupt. If it is determined in step S15 that the rotation speed N does not change, it is determined that the rotation is abnormal, and the application of voltage to the motor is stopped (step S16).

This makes it possible to detect abnormal rotation of the motor at an early stage and prevent seizure of the motor.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the case where the invention is applied to the air purifier is taken as an example, but the present invention can be widely applied to devices configured to control the rotation speed of the motor by adjusting the ignition phase angle. Is something that can be done. Various other design changes can be made without departing from the scope of the present invention.

<Effects of the Invention> As described above, according to the motor control device of the first invention, even if the rotation of the motor is apparently detected due to noise or the like entering the rotation speed detecting means, the ignition is performed. If it is determined that the phase angle is not within the normal range,
It is possible to determine that the rotation of the motor is abnormal and shut off the power of the motor by the power stopping means.

Further, according to the motor control device of the second aspect of the invention, an abnormality in the rotation of the motor is detected by changing the ignition phase angle of the power source supplied to the motor and examining the change in the rotation of the motor at this time. However, when it is determined that the rotation of the motor is abnormal, the power supply of the motor can be cut off by the power supply stopping means.

Therefore, in any case, the abnormal rotation of the motor can be reliably identified, and the occurrence of the accident of the motor can be prevented.

[Brief description of drawings]

FIG. 1 is a graph for explaining the influence of the load variation on the phase angle, FIG. 2 is a block diagram showing the overall configuration of a motor control device according to an embodiment of the present invention, and FIG. 3 is a control circuit. FIG. 4 is a flow chart for explaining the protection operation of the first embodiment, FIG. 4 is a flow chart for explaining the protection operation of the first embodiment of the control circuit, and FIG. 5 is a partial sectional view of a general motor. 6 and 7 are views showing the positional relationship between the stop position of the rotating magnet plate and the magnet detecting element. 2 ... Triac, 3 ... Motor, 5 ... Rotating magnet plate, 6 ... Hall IC, 7 ... Control circuit, 71 ... Rotation speed detection unit, 72 ... Rotation speed control unit, 73 ... Abnormality detection Section, 74 ... Power supply stop section, 75 ... Phase angle storage section

Claims (2)

[Claims] 1. A rotation speed detection means (71) for detecting a rotation speed of a motor (3) and a rotation control means (72) for controlling the rotation speed of the motor (3) by adjusting an ignition phase angle. A motor for rotating the motor (3) at a constant speed by changing the firing phase angle based on the comparison result between the rotation speed detected by the rotation speed detection means (71) and the target rotation speed. In the control device, a storage means (75) for storing the range of ignition phase angles θmin to θmax expected within a normal load range in association with the number of revolutions, and the ignition phase angle is the detected number of revolutions. Power supply stopping means (74) for shutting off the power applied to the motor (3) when the ignition phase angle range θmin to θmax stored in the storage means (75) is exceeded. A motor control device characterized by: 2. A rotation speed detection means (71) for detecting the rotation speed of the motor (3) and a rotation control means (72) for controlling the rotation speed of the motor (3) by adjusting the firing phase angle. A motor for rotating the motor (3) at a constant speed by changing the firing phase angle based on the comparison result between the rotation speed detected by the rotation speed detection means (71) and the target rotation speed. In the control device, the rotation control means (72) is capable of forcibly changing the firing phase angle, and even if the rotation control means (72) changes the firing phase angle,
Motor control characterized by having a power stopping means (74) for cutting off the power applied to the motor (3) when the rotation speed detected by the rotation speed detecting means (71) does not rise or fall. apparatus.