JPH088769B2 - Half-wave drive circuit for single-phase brushless motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a brushless motor that controls the rotation of a rotor in a single phase.

2. Description of the Related Art Conventionally, this type of brushless motor has a configuration as shown in FIGS. 4 and 5 are diagrams showing the arrangement of parts of a conventional brushless motor, and FIG. 6 is a block diagram of the brushless motor. In the figure, 1 is a case composed of a lower case 1A and an upper case 1B,
A rotor 2 is rotatably and rotatably supported in the case 1. Further, permanent magnets 3 and 4 are attached to the lower portion of the rotor 2 at positions symmetrical with respect to the center.
Reference numeral 5 is a coil attached to the lower case 1A, and the permanent magnets 3 and 4 are attracted by the magnetic field generated by energizing the coil 5 to rotate the rotor 2. Reference numeral 6 is a magnet for positioning the rotor 2 at the initial position between the permanent magnets 3 and 4, which is disposed in the lower case 1A and is for initial positioning of the rotor 2 when the power is off. 6 and permanent magnet
Since the polarities of 3 and 4 are the same, it repels and the rotor 2 stops 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 is arranged in the lower case 1A. The magnetic sensor 7 is arranged at a position affected by the magnetic force of the permanent magnets 3 and 4 of the rotor 2. The board 9 on which the components are mounted is disposed on the lower case 1A and then covered with the resin 10. 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 positions of the permanent magnets 3 and 4, and a signal from the magnetic sensor 7 is used to switch the switching element 11 that controls the energization of the coil 5. In FIG. 6, 13 is a constant voltage diode and 14 is a resistor.

In such a configuration, the permanent magnet 3 has the magnetic sensor 7
When it is located above, 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 rotor 2, a torque for attracting the permanent magnet 4 is generated, and the rotor 2 rotates. When the permanent magnet 4 moves close to the coil 5, the permanent magnet 3 moves from above the magnetic sensor 7, so that the output of the magnetic sensor 7 is turned off, the switching element 11 is turned off, and a current flows through the coil 5. The flow stops, the attractive force of the permanent magnet 4 and the coil 5 disappears, and the rotor 2 continues to rotate by inertia. Then a permanent magnet
3 and 4 will continue to move in the same way as before with the opposite state.

Here, a force that resists the movement of the rotor 2 that tries 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 magnets 3 and 4 of the rotor 2, and The sensor 7 has a hysteresis width (hereinafter referred to as BW-L) between a detection level when the detection is turned on (hereinafter referred to as BH-L) and a detection level where the detection is turned on (hereinafter referred to as BL-H).
Therefore, when the rotor 2 loses the attractive force of the coil 5 at BL-H and then yields to the repulsive force of the magnet 6 for initial positioning of the rotor 2 and rotates in the reverse direction, the rotor 2 becomes BH- After returning to L, normal rotation is again performed by the attractive force of the coil 5, and after repeating several times, the repulsion of the magnet 6 for initial positioning of the rotor 2 by the acceleration obtained from BH-L to BL-H. You will overcome the power and overcome it.

However, such a conventional brushless motor has a problem that it may not be able to rotate under the worst conditions (when BW is narrow) due to variations in BW of the magnetic sensor.

In addition, there is a limit in the current technology to suppress the variation in BW of the magnetic sensor, and it cannot be solved.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a brushless motor that is not affected by variations in BW of a magnetic sensor.

Means for Solving the Problems In order to solve such problems, the present invention provides a rotor having a permanent magnet, a magnet for positioning the rotor at an initial position between the permanent magnet, and the rotor. A coil for rotating the child, a switching element inserted and connected between the coil and a power source, a magnetic sensor for detecting the position of a permanent magnet of the rotor and controlling switching of the switching element, and this magnetic sensor. And a switching element and a delay circuit inserted and connected between the current limiting element and the magnetic sensor or between the current limiting element and the switching element. In addition, a timer circuit is added to turn on the switching element for a certain time when the power is turned on.

Action With this configuration, even when the rotor is vibrating without being able to rotate normally due to the repulsive force of the initial positioning magnet of the rotor, the delay occurs even after the magnetic sensor is turned off by BL-H. Even after the switching element is turned on by the circuit and the magnetic sensor is turned on by BH-L, the switching element is turned off by the delay circuit and the BW of the magnetic sensor is apparently widened. Due to the acceleration obtained between the rotors, the rotor overcomes the repulsive force and is allowed to rotate normally, so that it is possible to eliminate the influence of variations in the BW of the magnetic sensor.

In addition, by providing a timer circuit that conducts the switching element for a certain period of time when the power is turned on, switching is performed for a certain period of time when the power is turned on even if the permanent magnet of the rotor rarely stops directly above the rotor initial positioning magnet. Since the rotor moves due to the attractive force of the coil when the element conducts,
The initial position of the rotor is always returned to the initial position determined by the repulsive force of the magnet, so that the rotor cannot be disabled.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings of FIGS.

FIG. 1 shows a block circuit of a brushless motor according to an embodiment of the present invention, FIG. 2 shows a diagram for explaining the operating principle of the motor, and FIG. 3 shows a specific circuit.
1 to 3, the same parts as those of the conventional motor shown in FIGS. 4 to 6 are designated by the same reference numerals. In the figure, reference numeral 15 is a delay circuit, which is inserted and connected between the current limiting element 12 and the magnetic sensor 7, and is magnetic only when the rotor is vibrating due to the repulsive force of the initial positioning magnet of the rotor. In addition to the BW of the sensor 7, the ON period of the switching element 11 is extended and the energization period of the coil 5 is extended. As shown in FIG. 3, the delay circuit 15 is composed of transistors Q1 and Q2, diodes D1 and D2, resistors R1, R2 and R3, and a capacitor C1. In the circuit of FIG. 3, when the magnetic sensor 7 such as a Hall element is switched from ON to OFF, the potential at the point A gradually rises to (diode forward voltage + base-emitter voltage of the transistor Q1). When it reaches, the transistor Q1 is turned on, the transistor Q2 is turned off, and the switching element 11 is turned off after a certain time delay from the turning off of the magnetic sensor 7. On the contrary, when the magnetic sensor 7 is turned on, the transistor Q1 is turned off at the point A because the charging voltage of the capacitor is discharged through the diode D1. It turns on after a certain delay.

The delay circuit 15 may be inserted and connected between the current control element 12 and the switching element 11. Reference numeral 16 is a timer circuit which conducts a current through the current limiting element 12 for a certain period of time when the power is turned on to conduct the current.

With such a 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 switching is performed with a certain time delay. Element 11 turns on and coil 5
An electric current flows through the rotor 2, a torque for attracting the permanent magnet 3 is generated, and the rotor 2 rotates. When the permanent magnet 3 moves close to the coil 5, the permanent magnet 4 moves from above the magnetic sensor 7, so that the output of the magnetic sensor 7 is turned off, and the switching element 11 is turned off with a certain time delay. Then, no current flows through the coil 5, the attraction force between the permanent magnet 3 and the coil 5 is lost, and the rotor 2 continues to rotate by inertia. After that, the permanent magnets 3 and 4 continue to move in the same manner as described above in the opposite state.

Here, the force that resists the movement of the rotor 2 that tries to continue rotating due to inertia exists as the repulsive force between the magnet 6 for initial positioning of the rotor 2 and the permanent magnets 3 and 4 of the rotor 2, but In the embodiment, for example, even when the rotor 2 reversely rotates and vibrates, the detection level BH-L in which the magnetic sensor 7 is turned on from the detection off and the detection level BL-H in which the magnetic sensor 7 is turned off from the detection on.
Since there is a delay time due to the delay circuit 15 in addition to the hysteresis width BW between, 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. , When the rotor 2 yields to the repulsive force of the magnet 6 for initial positioning of the rotor 2 and rotates in the reverse direction, the rotor 2 returns to BH-L, performs normal rotation again by the attractive force of the coil 5, and repeats several times. The acceleration obtained during the period from BH-L to BL-H and the delay time in the delay circuit 15 overcomes the repulsive force of the magnet 6 for initial positioning of the rotor 2 and overcomes it.

Since the delay time of the delay circuit 15 is set to a fixed time, the vibration of the rotor 2 gradually increases in acceleration and amplification of the vibration increases, so that the repulsive force of the magnet 6 for initial positioning can be overcome. Further, when the rotor 2 continues to rotate normally, the delay time at BH-L and BL-H is generated in the same rotation direction of the rotor 2, so that it has almost no effect on the energization period of the coil 5 as in the conventional case. It can be designed according to the design specifications.

If the permanent magnet 3 or 4 of the rotor 2 is stopped just above the initial positioning magnet 6, the resistor R4 and the capacitor C2 forming the timer circuit 16 when the power is turned on.
The transistor Q3 is turned on for a fixed time (about 10 ms) determined by the time constant of, and the switching element 11 is turned on, so that the coil 5 is energized and the permanent magnet 3 or 4 of the rotor 2 is pulled toward the coil 5 to Since the permanent magnet 3 or 4 moves from directly above the initial positioning magnet 6, the permanent magnet 3 or 4 will not be unable to start. In FIG. 3, D3 is a diode.

As described above, according to the present invention, the delay is added to the width of BW determined by the performance of the magnetic sensor only when the rotor vibrates and it is necessary to overcome the repulsive force of the initial positioning magnet of the rotor. Since the ON period of the current flowing in the coil can be extended by the sum of the circuit delay times, the rotor can be rotated without yielding to the repulsive force of the initial positioning magnet of the rotor, and the BW variation of the magnetic sensor can be varied. It is possible to provide a brushless motor that is not affected by.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a brushless motor according to an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining the operating principle of the motor, and FIG. 3 is a circuit diagram showing a specific circuit of the motor. 4 and 5 are a sectional view and an exploded perspective view showing the arrangement of parts of a conventional brushless motor, and FIG. 6 is a block circuit diagram of the motor. 2 ... Rotor, 3,4 ... Permanent magnet, 5 ... Coil, 6 ...
… Magnet, 7… Magnetic sensor, 11… Switching element,
12 …… Current limiting element, 15 …… Delay circuit, 16 …… Timer circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sueo Matsumoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Tetsuro Niimura 390 Umeda, Kosai City, Shizuoka Prefecture Tsutomu Kinoshita 390 Umeda, Kosai City, Shizuoka Asmo Stock Association In-house (56) References JP-A-60-91853 (JP, A) Actual development: 60-141675 (JP, U)

Claims (1)

[Claims] 1. A rotor having a permanent magnet, a magnet for positioning the rotor at an initial position between the permanent magnet, one coil for rotating the rotor, and this coil and a power supply. A switching element inserted and connected between the magnetic sensor and the magnetic sensor that detects the position of the permanent magnet of the rotor and outputs a signal corresponding to the detected position; and an insertion connection between the magnetic sensor and the switching element. Between the current limiting element and the magnetic sensor,
Alternatively, a half-wave drive of a single-phase brushless motor including a delay circuit that is inserted and connected between the current limiting element and the switching element, and delays the phase shift of the output of the magnetic sensor for a fixed time and outputs the delayed phase shift to the switching element. circuit.