JPH05236783A - Rotational direction identifying method for two-phase unipolar sensorless motor - Google Patents

Abstract

PURPOSE:To provide a rotational direction identifying method for two-phase unipolar sensorless motor through which reverse rotation can be prevented by recognizing the rotational direction of the motor. CONSTITUTION:The rotational direction identifying method is applied on a fan motor having a cogging stop position, i.e., a magnetic stop position, different from an electric lock position, i.e., an electric stop position, and the method takes advantage of the asymmetry in the waveform of counter electromotive force induced in the stator through rotation of the rotor. In other words, only the waveform of counter electromotive force is selected (101) and thus selected waveform is subjected to differentiation (102), zero-cross comparison (103) and integration (104) and thus integrated waveform is compared (105) with a not integrated waveform thus identifying the rotational direction of the motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-phase unipolar sensorless motor, and more particularly to a two-phase unipolar sensorless motor capable of discriminating the rotation direction in a fan motor having a magnetic stop point and an electric stop point different from each other. The present invention relates to a technique effectively applied to a rotation direction identification method.

[0002]

2. Description of the Related Art Conventionally, as a fan motor for cooling or the like, for example, a stator that generates a magnetic field in an excited state and a rotor that obtains a rotational force by electromagnetic interaction with the stator are used, and an induced voltage of a coil is used. A sensorless type brushless motor has come to be used, and in many cases, rotation control is performed by an electronic circuit made into a semiconductor chip.

In this case, as the rotor rotates, the magnet fixed to the rotor moves, so that the magnetic flux penetrating the stator changes with time, and this change in magnetic flux causes counter-electromotive force in the coil wound around the stator. Electric power is generated.

Further, when the motor is started, the motor is in a stopped state and no counter electromotive force is generated in the coil.
After the phase coils have been forcibly excited to start the motor and the rotor has started to rotate, rotation control is performed by detecting the back electromotive force generated in the coils.

[0005]

However, in the above-mentioned prior art, since the two-phase coils are only excited alternately, the rotation direction of the motor cannot be switched midway, and the motor first moves in the opposite direction. If you start to turn to, there is a problem that it continues to reverse. In particular,
When used as a fan motor, there is a problem that a predetermined cooling effect cannot be obtained unless it rotates in the forward rotation direction.

Therefore, an object of the present invention is to provide a method for identifying the rotation direction of a two-phase unipolar sensorless motor, which can recognize the rotation direction of the motor and prevent reverse rotation when driving the two-phase unipolar sensorless motor. It is in.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, the method for identifying the rotational direction of a two-phase unipolar sensorless motor according to the present invention comprises a stator that generates a magnetic field in an excited state and a rotor that obtains a rotational force by electromagnetic interaction with the stator, and the cogging stop position. Is a two-phase unipolar sensorless motor having a magnetic stop point that is different from an electric stop point that is an electric lock position, and detects a back electromotive force generated in a stator due to rotation of a rotor.

[0010]

According to the above-described method for identifying the rotational direction of the two-phase unipolar sensorless motor, the detected waveform of the counter electromotive force generated in the stator is used to identify the rotational direction of the rotor. The direction of rotation can be identified by the asymmetry of the waveform.

That is, the stator is formed asymmetrically in order to prevent the dead point from staying, and this utilizes the fact that the waveform of the counter electromotive force is asymmetrical between forward rotation and reverse rotation. This makes it possible to recognize the rotation direction of the motor and prevent reverse rotation.

[0012]

Embodiment 1 FIG. 1 is a flow chart showing a procedure of a rotation direction identification method which is an embodiment of a rotation direction identification method of a two-phase unipolar sensorless motor according to the present invention, and FIG. 2 is the identification of FIG. 1 in this embodiment. It is a wave form diagram in each step of the flow.

First, referring to FIG. 1, a method of identifying the rotational direction in the two-phase unipolar sensorless motor of this embodiment will be described.

In the rotation direction identifying method of the present embodiment, for example, the stator is obliquely cut to prevent dead point stop and formed asymmetrically, and a magnetic stop point which is a cogging stop position,
It is applied to fan motors whose electrical lock position is different from the electrical stop point, and detects the counter electromotive force generated in the stator due to the rotation of the rotor.The direction of rotation is detected by using the asymmetry of the detected waveform of this counter electromotive force. Are being identified.

For example, first, by detecting the counter electromotive force generated in the stator and selecting only this counter electromotive force waveform, the counter electromotive force waveform as shown in FIG. 2 (a) can be obtained. In this case, the description will be made assuming that the forward counter electromotive force waveform is p and the reverse counter electromotive force waveform is r (step 10).
1).

Then, the selected back electromotive force waveform p,
By differentiating r, the forward differential waveform p1 or the reverse differential waveform r1 as shown in (b) can be obtained (step 102).

Further, the differential waveforms p1 and r1 are zero-crossed to obtain a normal rotating waveform p2 or a reverse rotating waveform r2 as shown in (c) (step 103).

Then, the comparison waveforms p2 and r2
And the negative comparator waveform of the comparator waveforms p2 and r2 are integrated and reset at the point A, so that the forward integral waveforms p3 and p3 ′ or the reverse integral waveform r3 as shown in (d). , R3 ′ can be obtained (step 104).

As a result, by comparing the integral waveforms p3 and p3 'immediately before the point A, when the negative integral waveform p3' is higher than the integral waveform p3, it is determined that the normal rotation is normal. Can be judged (Step 105, 1
06).

On the contrary, the integrated waveforms r3 and r3 'are compared immediately before the point A, and when the integrated waveform r3 is at a higher level than the negative integrated waveform r3', it can be judged that the waveform is reversed (step). 105, 107). This makes it possible to identify whether the motor is rotating in the forward rotation direction or the reverse rotation direction.

Therefore, according to the method for identifying the rotation direction of the two-phase unipolar sensorless motor of this embodiment, the waveform of the counter electromotive force generated in the stator due to the obliquely cut shape for preventing the dead point of the stator from being stopped is generated. Due to the asymmetry, the rotation direction is identified by utilizing the asymmetry of the counter electromotive force waveforms p and r, and the operation is continued in the case of forward rotation, while the rotation direction is determined in the case of reverse rotation. Can be changed and the order of excitation can be changed so as to achieve normal rotation, and a cooling effect as a fan motor can be obtained.

[0022]

[Embodiment 2] FIG. 3 is a flow chart showing a procedure of a rotation direction identification method which is another embodiment of the rotation direction identification method of the two-phase unipolar sensorless motor of the present invention, and FIG. It is a waveform diagram in each step of the identification flow.

In the method for identifying the rotational direction in the two-phase unipolar sensorless motor according to the present embodiment, the stator is shaving obliquely to prevent dead point retention and asymmetrically formed, as in the first embodiment. The present invention is applied to a fan motor in which the static stop point and the electric stop point that is the electric lock position are different. The difference from the first embodiment is that the zero cross-compare back electromotive force waveform is not integrated and a large frequency is applied. The point is to identify the rotation direction by using the clock signal of.

That is, as shown in the rotational direction identification flow of FIG. 3, steps 301 to 303 are the same as those in the first embodiment, and therefore step 304 and subsequent steps will be described.

For example, in step 304, FIG.
As shown in (d), a clock signal c having a frequency much higher than the rotation frequency of the motor is prepared. Then, the number of pulses in which the prepared clock signal c enters in the section of Hi level or Lo level in one cycle of the zero-cross-compared comparison waveforms p2, r2 obtained in step 303 is counted (step 305). ..

As a result, the numbers of pulses in the Hi level and Lo level sections are compared, and as shown in (e), the clock signal c of the mp pulse in the Hi level section and the np pulse in the Lo level section is assumed to be normal rotation. If you enter, mp <
When it is np, it can be determined that the rotation is forward based on the assumption (steps 306 and 307).

Further, if the mr pulse clock signal c is input in the Hi level section and the nr pulse section is input in the Lo level section assuming reverse rotation, it can be determined that the reverse rotation occurs when mr> nr (steps 306 and 308). ).

Therefore, according to the method for identifying the rotation direction of the two-phase unipolar sensorless motor of this embodiment, the counter electromotive force waveforms p and r of forward rotation or reverse rotation and the clock signal c are used, so Similarly, it is possible to identify the rotation direction by utilizing the asymmetry of the back electromotive force waveform generated in the stator.

The invention made by the present inventor has been specifically described above based on the first and second embodiments. However, the present invention is not limited to the above-mentioned embodiments and various modifications are possible without departing from the scope of the invention. Needless to say, it can be changed.

For example, regarding the rotation direction identification method,
Various modifications are conceivable, and in particular, it becomes possible by utilizing the asymmetry between the forward rotation and the reverse rotation due to the difference between the magnetic stationary point and the electrical stationary point.

In the above description, the case where the invention made by the present inventor is mainly applied to the rotation direction identification method used for a fan motor, which is the field of use of the invention, has been described, but the invention is not limited to this. It is also widely applicable to the two-phase unipolar sensorless motor of.

[0032]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, the magnetic stop point at the cogging stop position and the electric stop point at the electrical lock position are made different from each other, and the counter electromotive force generated in the stator due to the rotation of the rotor is detected. The rotation direction can be identified by utilizing the asymmetry of the detected waveform of.

As a result, the reverse rotation of the motor can be prevented by recognizing the rotation direction, and particularly when applied to the fan motor, the rotation direction of the two-phase unipolar sensorless motor capable of obtaining a predetermined cooling efficiency. An identification method can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure of a rotation direction identification method that is Embodiment 1 of a rotation direction identification method for a two-phase unipolar sensorless motor of the present invention.

2 is a waveform diagram in each step of the identification flow of FIG. 1 in Embodiment 1. FIG.

FIG. 3 is a flowchart showing a procedure of a rotation direction identification method which is Embodiment 2 of the rotation direction identification method of the two-phase unipolar sensorless motor of the present invention.

FIG. 4 is a waveform diagram in each step of the identification flow of FIG. 3 in the second embodiment.

[Explanation of symbols]

 p Forward rotation counter electromotive force waveform p1 Forward rotation differential waveform p2 Forward rotation comparator waveform p3 Forward rotation integral waveform r Reverse rotation back electromotive force waveform r1 Reverse rotation differential waveform r2 Reverse rotation comparator waveform r3 Reverse rotation integral waveform c clock signal

Claims (1)

[Claims] 1. A stator comprising a stator that generates a magnetic field in an excited state and a rotor that obtains a rotational force by electromagnetic interaction with the stator, and a magnetic stationary point that is a cogging stop position and an electric lock position that is an electrical lock position. 2 which is different from the static stop
A phase unipolar sensorless motor, which detects a counter electromotive force generated in the stator due to rotation of the rotor,
A method for identifying a rotational direction of a two-phase unipolar sensorless motor, characterized in that the rotational direction is identified by utilizing the asymmetry of the detected waveform of the counter electromotive force.