JPH0646871B2 - AC synchronous motor driving method - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an AC synchronous motor, and more particularly to a method for regulating a rotation direction at the time of starting the AC synchronous motor.

2. Description of the Related Art A microcomputer or the like is used to control this type of AC synchronous motor, and a switching means such as a relay or a reed switch is used as its operation unit.

On the other hand, in the bidirectional rotating inductor type AC synchronous motor, the rotor is in a state where it can take two stable positions when stopped. Then, since a non-directional alternating magnetic field is applied to this, the rotation direction at the time of starting is not constant, and therefore a reverse rotation preventing means is required.

In the mechanical reverse rotation prevention means, when the rotor rotates in the reverse direction, the rotation in the forward direction is corrected by the reverse rotation prevention lever or the like after several steps of rotation. With such startup, the rising operation is likely to be unstable and hunting development is likely to occur. These phenomena cause time and position control errors. Especially when the rotor is rotated intermittently, a large error appears.

OBJECT OF THE INVENTION It is an object of the present invention to stabilize the rising of the rotation of an AC synchronous motor of this kind and to accurately regulate the rotation direction of the rotor by operating an electric signal.

SUMMARY OF THE INVENTION Therefore, according to the present invention, before starting the AC synchronous motor, a DC voltage is applied to the excitation winding of the stator to make the rotor in an unstable state first, and then the DC voltage is cut off. After shifting to one of the stable positions, an AC voltage for starting is applied after that. When a voltage is applied to the excitation winding of the stator in this order, the rotation direction of the rotor can be accurately regulated in either direction. The rotation direction of the rotor is
It can be set in either direction by selecting the initial polarity of the AC voltage immediately before activation.

Configuration of the Invention Hereinafter, the configuration of the present invention will be specifically described with reference to the drawings.

First, FIG. 1 shows a drive circuit 2 of an AC synchronous motor 1. The AC synchronous motor 1 has a stator 8 and a permanent magnet rotor 9. Further, the drive circuit 2 constitutes a bridge circuit including four control transistors 31, 32, 33 and 34, and is connected to the DC power supply 4. The transistors 31 and 32 are controlled by the transistors 51 and 52, and control signals S1, S2, S3, and S4 are applied to their bases by a control computer or the like. In addition, the resistor 6,
Reference numeral 7 is for biasing or current limiting.

By the way, when the other control signals S1 and S4 are both at the “L” level and the other control signals S2 and S3 are at the “H” level, both the transistors 31 and 33 are in the ON state. Current flows in the synchronous motor 1 in the direction indicated by the solid line.

Further, when the control signals S1 and S4 are at the “H” level and the other control signals S2 and S3 are at the “L” level, the transistors 32 and 34 are turned on. That is, a current flows in the direction of the arrow indicated by the dotted line. By such a switching operation, the AC voltage V2 from the DC voltage V is applied to the AC synchronous motor 1.

Next, FIG. 2 shows changes in voltage according to the driving method of the present invention on the time axis of time t. At the beginning of driving,
For example, the direct-current voltage V1 in the positive direction over a predetermined time T1
Is applied. Then, after an appropriate time T2, the AC voltage V2 is applied by the control as described above.
Both the DC voltage V1 and the AC voltage V2 are applied to the excitation winding in the stator 8 of the AC synchronous motor 1, but the former DC voltage V1 regulates the rotational position of the rotor 9 in a stationary state to an unstable state. The latter AC voltage V2 is for driving the rotor 9 at a regular rotation speed in a predetermined rotation direction after regulating the rotation position of the rotor 9.

Operation of the Invention Next, the operation of the driving method will be described with reference to FIG.

FIG. 3 shows the positional relationship between the exciting magnetic poles 81, 82 and 83 of the stator 8 and the magnetic poles N and S of the rotor 9. Excitation magnetic pole 81,
82 and 83 are alternately magnetized with different polarities at the time of driving, and the auxiliary exciting magnetic pole 83 among them is the other exciting magnetic pole 8
The reluctance distribution is shifted by changing the interval, that is, the pitch on the rotation angle from 1, 82. Specifically, the exciting magnetic pole 8
With reference to 1 and 82, the exciting magnetic pole 83 has an electrical angle of 90 °.
It has been staggered. The rotors 9 are magnetized at equal intervals and with different polarities.

When the exciting magnetic poles 81, 82, 83 are not excited, that is, when the rotor 9 is not rotating, the rotor 9 tries to enter the adjacent magnetic poles of the rotor through the exciting magnetic poles of the stator. It will stop at the minimum position of the reluctance or at a stable phase.
The position of the rotor 9 is different in phase by one magnetic pole. The rotor 9 has two positions and two
It is stable in two states and therefore the stop position is not constant. Here, if there is no exciting magnetic pole 83, the rotor stops at a position where the boundary of the rotor magnetic pole and the center of the exciting magnetic pole of the stator coincide with each other.
As a result of the force that the center of 3 and the magnetic pole boundary of the rotor try to coincide with each other, the rotor stops at a position slightly shifted to the right from the position where the center of the exciting magnetic poles 81 and 82 coincides with the magnetic pole boundary of the rotor. When the AC voltage V2 is directly applied in this state, the rotation direction becomes uncertain depending on the position of the rotor 9 or the state of.

However, in the driving method of the present invention, as described above, since the DC voltage V1 is applied at the initial stage of driving, the rotation direction becomes constant. That is, when the exciting magnetic poles 81, 82, 83 of the stator 8 are magnetized by the DC voltage V1 with the polarities shown in the lower part of FIG. 3, the rotation phase of the rotor 9 becomes the magnetic attraction force and the repulsive force. From the relation, that is, the reluctance distribution relation, the state of the unstable position shown in FIG. 3 is obtained.

More specifically, at the above-mentioned position, the exciting magnetic pole and the rotor magnetic pole stop at a position where the centers of the exciting magnetic poles 81 and 82 and the center of the rotor magnetic pole are substantially aligned with each other due to the mutually opposing poles attracting each other. The reason why they do not completely match is that the pitch of the exciting magnetic poles 83 is deviated by an electrical angle of 90 °, and the center of the rotor magnetic poles is 8
Stop at a position slightly left of the center of 1, 82.

After that, when the DC voltage V1 is turned off, the rotor magnetic poles facing the excitation magnetic poles 81 and 82 are located slightly leftwardly displaced in the excited state as described above.
For example, in the exciting magnetic pole 81, the magnetic flux emitted from the N pole of the rotor is
As a result of attempting to enter the S pole to the right of the N pole via the exciting magnetic pole 81, the rotor receives a force on the left side of the drawing due to the reluctance distribution relationship. Further, as a result of 82 and 83 also receiving a force to the left for the same reason, after a proper time T2, the rotor is
From the reactance distribution relationship, the position must always be
The phase shifts to the position shown in the figure. Next, an AC voltage V2 is applied with a predetermined polarity, and N, S, and N are applied to the magnetic poles 81, 82, and 83, respectively, as shown in parentheses at the top of FIG.
When the poles are magnetized, the rotation direction of the rotor 9 is restricted in the arrow direction shown in FIG. Therefore, regardless of whether the rotor 9 is in the position or the phase at the time of the stop, the rotation direction of the rotor 9 is accurately regulated in one direction.

FIG. 4 shows the relationship between the stable position and the unstable position of the rotor 9 in relation to the times T1, T2, T3. When the DC voltage V1 is turned off, that is, time T
In the period of 2, the rotor 9 moves from the unstable position to the stable position, and when it enters the time T3, as shown by the dotted line,
While vibrating, he eventually tries to stop. When the AC voltage V2 is applied while the rotor 9 is moving, that is, while the inertia in the desired rotation direction is present in the rotor 9,
The rotation direction of the rotor 9 is regulated in a more stable state. When the rotor 9 comes closest to the desired rotation direction, that is, at the initial peak of vibration,
Even when the AC voltage V2 is applied, the rotation direction can be regulated. The time T2 already described is set to the most optimum value in relation to the characteristics of the AC synchronous motor 1 in consideration of the above phenomenon.

Next, FIG. 5 shows the rotor 9 in the direction opposite to the above description.
The waveform of the AC voltage V2 when rotating is shown.
Since the initial polarity of the AC voltage V2 here is opposite to the polarity shown in FIG. 2, the rotation direction of the rotor 9 is set to the opposite direction.

Field of Application of the Invention Although the method of the present invention is premised on the existence of the permanent magnet type rotor 9, the magnetized state of the rotor 9 may be formed on a circumferential surface centered on the rotation axis. Also, it may be magnetized on a plane orthogonal to the rotation axis.

EFFECTS OF THE INVENTION In the present invention, the following unique effects are obtained.

First of all, since the start-up at the time of start-up is stable, there are few errors in time and position control and the accuracy is improved especially during intermittent rotation. Secondly, since the position control of the rotor at the initial stage of start-up is performed by the DC voltage, it can be easily dealt with by changing the frequency by the conventional control means.

[Brief description of drawings]

FIG. 1 is a drive circuit diagram of an AC synchronous motor, FIG. 2 is a drive voltage waveform diagram, and FIG. 3 is an explanatory diagram showing the positional relationship of the motor.
FIG. 4 is an explanatory diagram showing the operation of the rotor, and FIG. 5 is an explanatory diagram showing the waveform of the drive voltage. 1 ... AC synchronous motor, 2 ... Drive circuit, 4 ... DC power supply, 8
... Stator, 9 ... Rotor, V1 ... DC voltage, V2 ... AC voltage.

Claims (1)

[Claims] 1. A rotor having a plurality of magnetic poles which are alternately magnetized with different polarities at equal intervals, and a stator having an exciting magnetic pole which is provided so as to face the magnetic poles of the rotor and is magnetized with alternating polarities. In an AC operating motor having a structure in which a rotor that is stationary in an unstable state is operated in a fixed direction by non-excitation, the exciting magnetic pole is different from the auxiliary magnetic pole that is different from the distance between other adjacent exciting magnetic poles. Having an exciting magnetic pole, the exciting magnetic pole of the stator is excited by a DC voltage for a predetermined time to make the rotor unstable, and then the DC voltage is turned off to move the rotor to a stable position. A method of driving an AC synchronous motor, characterized in that a driving AC voltage is applied.