JPH03261392A - Motor controller - Google Patents

Abstract

PURPOSE:To make the hysteresis width BW of a magnetic sensor apparently wider and eliminate the influence of the variation of the hysteresis width BW of the magnetic sensor by a method wherein a pulse generator generating a negative pulse is connected between both the terminals of a current limiting device inserted between the magnetic sensor and a switching device. CONSTITUTION:By a signal from a pulse generator 15, a current is applied to a coil 5 for a period longer than a hysteresis width BW between a detection level BH-L at which a magnetic sensor 7 is turned from detection-OFF to detection-ON and a detection level BL-H at which the magnetic sensor 7 is turned from detection-ON to detection-OFF. If a rotor 2 yields to the repulsion force of an initial positioning magnet 6 and starts reverse rotation after the attraction force of the coil 5 is lost at the level BL-H, the rotor 2 is restored to a position of the level BH-L and starts normal rotation again by the attraction force of the coil 5. After such processes are repeated several times, the rotor 2 overcomes the repulsion force of the initial positioning magnet 6 by an acceleration obtained during a period between the levels BH-L and BL-H and during the period of the width of a pulse from the pulse generator 15.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a motor control device for controlling the rotation of a rotor in a brushless motor.

2. Description of the Related Art Conventionally, this type of motor control device has a configuration as shown in FIGS. 4 to 6. Note that FIGS. 4 and 5 are diagrams showing the arrangement of parts of a conventional motor control device, and FIG.
The figure is a block circuit diagram of the control device. In the figure, 1 is a case consisting of a lower case IA and an upper case IB, and a rotor 2 is rotatably supported in the case 1. Furthermore, permanent magnets 3.4 are attached to the lower part of the rotor 2 at symmetrical positions with respect to the center. Reference numeral 5 denotes a coil attached to the lower case IA, and when the coil 5 is energized, a magnetic field generated attracts the permanent magnets 3.4, causing the rotor 2 to rotate.

6 is a magnet for positioning the rotor 2 at the initial position between it and the permanent magnet 3.4, and is disposed in the lower case IA. Since the polarities of the magnet 6 and the permanent magnet 3.4 are the same, they repel each other, and the rotating motor 2 is stopped at a balanced position.

Reference numeral 7 denotes a magnetic sensor such as a Hall element, which is mounted on a substrate 9 together with other electronic components 8 and arranged in the lower case IA. Further, this magnetic sensor 7 is arranged at a position where it is influenced by the magnetic force of the permanent magnets 3.4 of the rotor 2. Further, the board 9 on which this component is mounted is covered with a resin 10 after being placed on the lower case IA.

Further, in FIG. 6, a switching element 11 such as a transistor is inserted and connected between the coil 5 and the power source. The output terminal of the magnetic sensor 7 is connected to the switching element 11 via a current limiting element 12 such as a resistor.

That is, the magnetic sensor 7 detects the position of the permanent magnet 3.4, and the switching element 11 that controls the energization of the coil 5 is switched based on the signal from the magnetic sensor 7.

In addition, in FIG. 6, 13 is a constant voltage diode, and 14 is a constant voltage diode.
is resistance.

In such a configuration, when the permanent magnet 3 is located on the magnetic sensor 7, the output of the magnetic sensor 7 is turned on, the switching element 11 is turned on, and the coil 5 is turned on.
A current flows through the magnet, generating torque to attract the permanent magnet 4, and the rotor 2 rotates. When the permanent magnet 4 moves close to above the coil 5, the permanent magnet 3 moves from above the magnetic sensor 7, so the output of the magnetic sensor 7 is turned off, the switching element 11 is turned off, and current flows through the coil 5. The current stops, the attractive force between the permanent magnet 4 and the coil 5 disappears, and the rotor 2 continues to rotate due to inertia.

Thereafter, the permanent magnet 3.4 will continue to move in the same way as described above, but in the opposite state.

Here, a force that resists the movement of the rotor 2 to continue rotating due to inertia exists as a repulsive force between the magnet 6 for initial positioning of the rotor 2 and the permanent magnet 3.4 of the rotor 2, and Since the sensor 7 has a hysteresis width (hereinafter referred to as BW) between the detection level from detection off to on (hereinafter referred to as BH-L) and the detection level from detection on to off (hereinafter referred to as BL-H), If the rotor 2 loses the attractive force of the coil 5 at BL-H and then succumbs to the repulsive force of the magnet 6 for initial positioning of the rotor 2 and rotates in the opposite direction, the rotor 2 will move to BH.
-L, the magnet 6 for initial positioning of the rotor 2 is rotated again by the attractive force of the coil 5, and after repeating several times, the acceleration obtained between BH-L and BL-H
It is necessary to overcome and overcome the repulsive force of

Problem to be Solved by the Invention However, with such conventional motor control devices, there is a problem in that under the worst conditions (when the BW is narrow), the motor may not be able to rotate due to variations in the BW of the magnetic sensor. Ta.

Furthermore, there is a limit to suppressing the variation in BW of the magnetic sensor with the current technology, and it has not been possible to solve the problem.

In view of the current situation, it is an object of the present invention to provide a motor control device that is not affected by variations in BW of magnetic sensors.

Means for Solving the Problems In order to solve these problems, the present invention provides a rotor having permanent magnets, a magnet for positioning the rotor at an initial position between the permanent magnets, and a rotor for positioning the rotor at an initial position between the permanent magnets. A coil for generating a magnetic field for rotating the rotor, a switching element inserted and connected between the coil and a power supply, and a magnet for detecting the position of the permanent magnet of the rotor and controlling switching of the switching element. The device includes a sensor, a current limiting element inserted and connected between the magnetic sensor and the switching element, and a negative pulse generator connected to both ends of the current limiting element.

Effect With this configuration, even after the magnetic sensor is turned off at BL-H, the switching element is turned on by the negative pulse generator, and the BW of the magnetic sensor is apparently widened.
It becomes possible to eliminate the influence of variations in BW of the magnetic sensor.

EXAMPLE Hereinafter, an example of the present invention will be explained using the drawings of FIGS. 1 to 3.

FIG. 1 shows a block circuit of a motor control device according to an embodiment of the present invention, FIG. 2 shows a diagram explaining the operating principle of the device, FIG. 3 shows a specific circuit, and FIG. 1 to 3, the same parts as those of the conventional apparatus shown in FIGS. 4 to 6 are given the same numbers. In the figure, 15 is a negative pulse generator, which is connected to both ends of the current limiting element 12, and in addition to increasing the BW of the magnetic sensor 7, extends the ON period of the switching element 11 to lengthen the energization period to the coil 5. do the work. As shown in FIG. 3, this pulse generator 15 includes transistors Q1 and Q2, a constant voltage diode D1, resistors R1 to R4, and a capacitor C.
1. In the circuit shown in FIG. 3, when the magnetic sensor 7 such as a Hall element is turned from on to off, point A changes from a low level to a high level. At this time, the potential at the 0 point gradually increases, and when it reaches (Zener voltage + base-emitter voltage of transistor Q1), transistor Q1 is turned on. Also, transistor Q
When magnetic sensor 7 is turned off and point A becomes high level until transistor Q1 is turned on, transistor Q
Since the base current flows through 2, it turns on. While this transistor Q2 is on, the switching element 11 such as a transistor is on even if the magnetic sensor 7 is off.

In addition, in Fig. 3, C2 and C3 are capacitors, and R5
, R6 are resistors, and D2 and D3 are diodes.

With this configuration, as shown in FIG. 2, when the permanent magnet 4 is located on the magnetic sensor 7, the output of the magnetic sensor 7 is turned on, and the switching element 1 is turned on.
1 is turned on, current flows through the coil 5, a torque is generated to attract the permanent magnet 3, and the rotor 2 rotates. When the permanent magnet 3 moves close to above the coil 5, the permanent magnet 4 moves from above the magnetic sensor 7.
The output of is turned off, the switching element 11 is turned off, current no longer flows through the coil 5, the attractive force between the permanent magnet 4 and the coil 5 disappears, and the rotor 2 continues to rotate by inertia.

Thereafter, the permanent magnet 3.4 will continue to move in the same way as described above, but in the opposite state.

Here, a force that resists the movement of the rotor 2 to continue rotating due to inertia exists as a repulsive force between the magnet 6 for initial positioning of the rotor 2 and the permanent magnet 3.4 of the rotor 2, but the actual In the embodiment, the magnetic sensor 7 receives a signal from the pulse generator 15 in addition to the hysteresis level BW between the detection level BH-L that changes from detection off to on and the detection level BL-)1 that changes from detection on to off. As a result, the coil 5 is energized for a longer period than before, and after the rotor 2 loses the attractive force of the coil 5 at BL-H, it succumbs to the repulsive force of the magnet 6 for initial positioning of the rotor 2 and reverses. When rotating, rotor 2 is B
Returning to H-L, normal rotation is performed again by the attractive force of the coil 5, and after repeating several times, due to the acceleration obtained during the period from BH-L to BL-H and the pulse width period from the pulse generator 15. , the repulsive force of the magnet 6 for initial positioning of the rotor 2 is overcome and overcome.

Effects of the Invention As described above, according to the present invention, the ON period of the current flowing through the coil can be lengthened by the pulse width of the negative pulse generator in addition to the BW width determined by the performance of the magnetic sensor.
It is possible to provide a motor control device that can rotate the rotor without succumbing to the repulsive force of the magnet for initial positioning of the rotor, and is not affected by variations in BW of the magnetic sensor.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of a motor control device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram explaining the operating principle of the device, and FIG. 3 is a circuit diagram showing a specific circuit of the device. Fourth
5 are a sectional view and an exploded perspective view showing the arrangement of parts of a conventional motor control device, and FIG. 6 is a block circuit diagram of the control device. 2... Rotor, 3.4... Permanent magnet, 5... Coil, 6... ・Magnet, 7. ・Magnetic sensor, 11. ・
Switching element, 12. Current limiting element, 15.
・Pulse generator.

Claims (1)

[Claims] A rotor having a permanent magnet, a magnet for positioning the rotor at an initial position between the permanent magnets, a coil for generating a magnetic field for rotating the rotor, and a power source and the coil. a switching element inserted and connected between the two; a magnetic sensor that detects the position of the permanent magnet of the rotor and controls switching of the switching element; and a current limiting element inserted and connected between the magnetic sensor and the switching element. , and a negative pulse generator connected to both ends of the current limiting element.