JP2722644B2 - Stop device for brushless motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for a brushless motor.

2. Description of the Related Art In recent years, with the development of the FA and OA fields, drive motors used in peripheral devices have been developed using mechanical devices such as brushes and commutators in order to extend their life, increase reliability, and reduce the shape of the motor. A so-called brushless motor having an electronic switch using a transistor has been increasingly used in place of a conventional DC motor having a simple switching mechanism.

In particular, a brushless motor is used for a memory mechanism, for example, a spindle motor in a floppy disk drive or an optical disk drive. Various characteristics are required for the spindle motor in the memory device. Among them, the operating characteristics of the spindle motor such as the start time and the stop time are strongly required.

Hereinafter, a conventional method for performing stop control of a brushless motor will be described with reference to the drawings.

FIG. 2 is a circuit block diagram of a stop device having a brake circuit for performing stop control of the brushless motor. In FIG. 2, reference numeral 13 denotes a controlled motor. An oscillator 1 generates a reference signal corresponding to the controlled speed.
Is a frequency divider for dividing the reference signal of the oscillator 1 as necessary. Reference numeral 14 denotes a speed detector capable of detecting the speed of the controlled motor. The output of the frequency divider 17 and the output of the speed detector 14 are input to five phase comparators. 6 is an error lamp, 17 is the controlled motor
13 is a position detector that detects the position of 12 movers forming 13. 16 is a start / brake switch, which is connected to 15 operation control circuits. The error amplifier 6, the position detector 17, and the operation control circuit 15 are respectively connected to 7 energization switching circuits. The energization switching circuit 7 is 8
Connected to the oscillation transistor. The driving transistor 8 supplies current to the driving coils 9, 10, and 11.

The operation of the stop control method of the brushless motor configured as described above will be described below.

First, to start the controlled motor 13,
Turn on the brake switch 16. The ON signal of the start / brake switch 16 reaches the operation control circuit 15 and instructs the operation switching circuit 7 to rotate the operation control circuit 15 and the controlled motor 13 in the forward direction. The rotation speed of the controlled motor 13 is detected by a speed detector 14. The rotation speed of the controlled motor 13 is determined by the oscillator 1 that generates the reference signal and, if necessary, the frequency divider 18 that divides the signal of the oscillator 1. The output of the speed detector 14 and the output of the frequency divider 18 are
The phases of the signals are compared, and the error signal is compared with the phase comparator 5.
Will output. The error signal is amplified and smoothed by the error lamp 6 and reaches the energization switching circuit 7 as a torque command signal. A mover constituting the controlled motor 13
The signal of the position detector 17 for detecting the position of the twelve also reaches the energization switching circuit 7. At this time, the energization switching circuit 7 drives the drive coils 9, 10 and 11 via the drive transistor 8 in order to perform a constant speed control by the operation control circuit 15 in the forward direction by the torque command signal of the error amplifier 6. Are sequentially energized.

Next, the operation when the start / brake switch 16 is turned off will be described.

When the start / brake switch 16 is turned off while the controlled motor 13 continues to rotate at a constant speed, the operation control circuit 15 outputs a command for rotating the controlled motor 13 in the reverse direction to the conduction switching circuit 7. . The energization switching circuit 7
Are driving transistors 9 and 10 via driving transistor 8
And 11 are sequentially energized so as to be reversed. By this operation, the controlled motor 13 is decelerated. At this time, the speed detector 14 always detects the speed via the controlled motor 13. The output of the speed detector 14 is input to the operation control circuit 15. The operation control circuit 15 includes the controlled motor 13
Is stopped, and a command to reduce the torque generation to zero is issued to the energization switching circuit 7, and the controlled motor 13 stops. The method for detecting the stop of the controlled motor 13 is based on
This is performed by comparing a signal obtained by dividing the speed reference signal, which is the output of the frequency divider 17 that determines the rotation speed of the speed controller 13 with the frequency divider inside the operation control circuit 15, with the signal of the speed detector 14. . The frequency division ratio in the operation control circuit 15 is set to be constant. If the frequency division ratio is, for example, N frequency division, the frequency of the speed reference signal is multiplied by 1 / N. When the speed reference signal obtained by multiplying the signal from the operation control circuit 15 and the speed detector 14 by 1 / N matches, a command is issued to the energization switching circuit 7 so that the torque generation becomes zero.

In other words, the controlled motor 13 is 1 / the rotation speed at the time of control.
Torque is applied in the reverse direction until N rotations are reached, and braking is applied.

However, in the above-described conventional technology, the rotation speed at which the braking operation of the controlled motor is released is determined by the frequency division ratio of the frequency divider built in the operation control circuit. This means that when the control rotation speeds are different, the rotation speed range in which the brake braking operation is performed is different. That is, when the rotation is controlled at a high speed, the braking operation is stopped before the vehicle is sufficiently decelerated, and the stop time is extended. Further, when the rotation is controlled at a low speed, since the reverse rotation torque is effective just before the stop, even if the brake is released after the speed is reduced to zero and the brake is released, the motor rotates in the opposite direction in a vigorous manner. In order to rotate in the reverse direction, the operation control circuit 15 operates to stop the controlled motor 13 again. That is, torque is generated in the normal rotation direction. Since the forward rotation torque is effective just before the stop, the vehicle rotates in the forward direction even if the brake is released after the speed is reduced to zero and the speed is reduced again. There is a problem that a phenomenon in which the normal rotation and the reverse rotation are continued forever occurs, and the operation cannot be stopped.

The present invention has been made in view of the above circumstances, and provides a brushless motor stopping device that can apply a brake to an appropriate rotating speed in order to shorten a stopping time even in a brushless motor rotating at any rotating speed. .

Means for Solving the Problems A brushless motor stopping device of the present invention for solving the above problems includes a drive coil of a multi-phase motor, a plurality of drive transistors connected to the drive coil, and a mover of the motor. A plurality of position detectors for detecting a position, an energization switching circuit for sequentially energizing the drive transistor according to the output of the position detector, a speed detector for detecting a rotation speed of the motor, and starting and braking of the motor. A start / brake switch for switching, an operation control circuit for instructing the energization switching circuit to start / brake / stop based on signals from the start / brake switch and the speed detector; and a reference signal corresponding to a rotation speed of the motor. An oscillator, a first divider for dividing the signal of the oscillator, a second divider for further dividing the output signal of the first divider, An output of the first frequency divider and a reference signal switching device having the input of the output of the second frequency divider as an input. When the signal of the start / brake switch is in the regulation command state, the reference signal is switched. The device outputs a signal of the second frequency divider to the operation control circuit, and outputs a signal of the first frequency divider to the operation control circuit when the rotation of the motor stops.

According to the present invention, with the configuration including the above-described reference signal switching device, an appropriate brake can be applied to the brushless motor having any rotational speed from low speed control to high speed control, and the stop time can be reduced.

Embodiment Hereinafter, a stop device for a brushless motor according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an example of a circuit block diagram of a device for stopping a brushless motor according to an embodiment of the present invention. In FIG. 1, portions having the same functions as those of the conventional brushless motor stopping device of FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, reference numeral 2 denotes a signal of an oscillator 1
13 is a first frequency divider that divides frequency to obtain a frequency corresponding to the rotation speed at the time of the control of 13. 3 is the first frequency divider 2
Is a second frequency divider for dividing the output of the second frequency divider. Reference numeral 4 denotes a reference signal switching device which receives the output of the first frequency divider 2 and the output of the second frequency divider 3 and outputs the input to the operation control circuit 15.

The operation of the brushless motor stopping device configured as described above will be described below.

First, the start / brake switch 16 is turned on to start the controlled motor 13. The ON signal of the start / brake switch 16 reaches the operation control circuit 15, and the operation control circuit 15 instructs the energization switching circuit 7 to rotate the controlled motor 13 in the normal rotation direction. The rotation speed of the controlled motor 13 is detected by a speed detector 14.

The rotation speed of the controlled motor 13 is determined by the oscillator 1 that generates the reference signal and, if necessary, the first frequency divider 2 that divides the signal of the oscillator 1. The speed detector 14
And the output of the first frequency divider 2 compare the phases of the two signals by a phase comparator 5, and the phase comparator 5 outputs an error signal. The error signal is amplified and smoothed by the error amplifier 6 and reaches the energization switching circuit 7 as a torque command signal. Further, a signal of a position detector 17 for detecting the position of the movable element 12 constituting the controlled motor 13 also reaches the energization switching circuit 7. At this time, the energization switching circuit 7 is operated by the operation control circuit 15 in the normal rotation direction so that the error amplifier 6
The drive coils 9, 10 and 11 are sequentially energized via the drive transistor 8 in order to perform control at a constant speed according to the torque command signal.

Next, the operation when the start / brake switch 16 is turned off will be described.

When the start / brake switch 16 is turned off while the controlled motor 13 continues to rotate at a constant speed, the operation control circuit
Reference numeral 15 outputs a command for rotating the controlled motor 13 in the reverse direction to the power supply switching circuit 7. The energization switching circuit 7
Are driving transistors 9 and 10 via driving transistor 8
And 11 are sequentially energized so as to be reversed. By this operation, the controlled motor 13 is decelerated. At this time, the speed detector 14 constantly detects the rotation speed of the controlled motor 13. The output of the speed detector 14 is the operation control circuit 15
Is input to the reference signal switching device 4. The operation control circuit 15 detects the stop of the controlled motor 13 and instructs the current supply switching circuit 7 to reduce the torque generation to zero, and the controlled motor 13 stops. The method for stopping the controlled motor includes the step of detecting the rotation speed of the controlled motor 13 by the speed detector.
14 and the output of the reference signal switching device 4 to which two signals of the first frequency divider 2 and the second frequency divider 3 are input, and the start / brake switch 16.

When the start / brake switch 16 is turned off, that is, when the mode of stopping the controlled motor 13 is set, the reference signal switching device 4 selects the signal of the second frequency divider 3 and outputs it to the operation control circuit 15. Since the output of the second frequency divider 3 is obtained by further dividing the output of the first frequency divider 2, even if the controlled motor 13 rotates at a high speed, the second frequency divider 3
By adjusting the frequency division ratio, the brake can be used even at low speeds. If the signal of the second frequency divider 3 is input to the operation control circuit 15 even after the brake is applied to just before the stop, a phenomenon occurs in which the normal rotation and the inversion are repeated. Therefore, the reference signal switching device 4 outputs the signal of the first frequency divider 2 to the operation control circuit 15 at the time when the controlled motor 13 is detected to be stopped based on the output signal of the speed detector 14. Since the operation control circuit 15 switches to the operation based on the signal of the first frequency divider 2, the controlled motor 13 does not repeat the normal rotation and the reverse rotation.

When the controlled motor 13 is controlled at a low speed, the reference signal input to the phase comparator 5 is realized by exchanging the outputs of the first frequency divider 2 and the second frequency divider 3. it can.

Effect of the Invention As described above, the present invention provides a frequency divider that divides the frequency of an oscillator in two stages, and has a function of switching two inputs according to the rotation state of a brushless motor using two types of frequencies as reference signals. By providing a reference signal switching device, the stop time of the brushless motor can be shortened.In particular, when using an IC, the frequency division ratio of the frequency divider can be adjusted for any rotational speed of the brushless motor. By setting the appropriate frequency division ratio of the motor, the other configuration can be the same, so that an IC with versatility can be designed, and therefore a brushless motor stopping device with a large degree of design freedom can be realized at low cost. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a brushless motor stopping device having a function of switching a reference signal according to an embodiment of the present invention.
FIG. 1 is a configuration diagram of a conventional brushless motor stopping device. DESCRIPTION OF SYMBOLS 1 ... Oscillator, 2 ... 1st frequency divider, 3 ... 2nd frequency divider, 4 ... Reference signal switching device, 7 ... Energization switching circuit, 8
... Driving transistors, 9 to 11 Driving coils, 14
Speed detector, 15… Operation control circuit, 16… Start brake switch, 17… Position detector.

Claims (1)

(57) [Claims] 1. A driving coil for a multi-phase motor, a plurality of driving transistors connected to the driving coil, a plurality of position detectors for detecting a position of a mover of the motor, and an output of the position detector. An energization switching circuit for sequentially energizing the drive transistor in response to the current, a speed detector for detecting a rotation speed of the motor, a start / brake switch for switching between starting and braking of the motor, and a start / brake switch and the speed detector. A braking control circuit that issues a start / brake / stop command to the energization switching circuit by a signal, an oscillator that issues a reference signal according to the rotation speed of the motor, and a first frequency divider that divides the signal of the oscillator. A second frequency divider for further dividing the output signal of the first frequency divider, and a reference signal switch receiving the output of the first frequency divider and the output of the second frequency divider as inputs Equipment and When the signal of the start / brake switch is in the braking command state, the reference signal switching device outputs the signal of the second frequency divider to the operation control circuit, and when the rotation of the motor stops, the first signal is output. A brushless motor stopping device for outputting a signal of the frequency divider to the operation control circuit.