JPS63213491A - Motor control system - Google Patents

Abstract

PURPOSE:To improve the starting characteristic of a motor by providing a circuit for increasing a motor coil current during a predetermined time synchronized with a motor signal. CONSTITUTION:A spindle motor control system for a magnetic disk device has a tachometer generator 13, a monostable multivibrator MM, an operational amplifier 24, Hall elements 34, 38, and transistors, etc. Power is supplied to motor coils 27-30 through a control circuit having a parallel unit of a transistor 41 and a current limiting resistor 42, and a timer 40 is connected to its base. Further, a circuit having the timer 40, the transistor 41 and a motor ON start signal input 43 is attached. When the start signal 43 is input thereto, the timer 40 is operated synchronously therewith to conduct the transistor 41 during the timer time to feed a large current to the coils 27 30, thereby generating a large starting torque. After the timer, the transistor 41 is interrupted, and the power is supplied through the resistor 42.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a motor control method, particularly a motor control method for starting an electric motor and rotating it at a predetermined rotation speed. [Prior Art] Floppy disk device, 2. Description of the Related Art In magnetic disk devices such as hard disk devices, a DC motor is used as a drive source, that is, a spindle motor, in order to rotate a magnetic disk at a predetermined rotational speed.

In conventional spindle motor control, when starting the spindle motor, a current determined by the coil resistance, the power supply voltage used, and a limiting resistor connected in series with the coil is applied to the coil, and the disk is rotated by the starting torque corresponding to this current. ing.

Further, even during steady rotation, a current determined by the coil resistance and the servo voltage is applied to the coil to keep the rotation of the disk constant.

[Problems to be Solved by the Invention] In the case of the above-mentioned conventional method, in order to prevent heat generation in the motor and to make the power supply smaller and cheaper, when determining the resistance value for controlling the power supply of the coil, the starting We had to consider the balance between torque and these factors. Conventionally, in order to prevent heat generation during steady rotation, the starting current was limited by a current limiting resistor set high in the coil, resulting in a sacrifice in starting torque.

FIG. 3 shows the configuration of a conventional motor drive circuit.

In FIG. 3, reference numeral 1 indicates a power supply voltage application point, and 1' indicates a ground potential. First, a voltage dividing circuit consisting of a series circuit of a resistor 2 and a diode 12 is connected between the power supply line and the ground line, and the voltage division value is determined by an amplifier AMP composed of a transistor 15, a resistor 3, a transistor 18, 21,
Resistors 4 to 7, diodes 17. ．． It is used as a power supply voltage for a mono-multivibrator MM consisting of 20 capacitors 19.

A protective diode 14 is connected to the base of the transistor 15.
Together with the tacho generator 13 for detecting the number of disk rotations.
is connected. The tacho generator 13 outputs a voltage according to the rotational speed, and the value is amplified by the amplifier AMP made up of the transistor 15, and applied to the differentiating circuit made up of the capacitor 16.
．． 21 to form a trigger pulse for the mono-multivibrator MM.

The output of the mono-multivibrator MM is taken out via a resistor 10, and by smoothing this with a capacitor 22, a DC voltage corresponding to the number of disk rotations is formed.

From this voltage, a comparator composed of an operational amplifier 24 forms a voltage difference between it and a reference voltage divided by a resistor 8.23, and further controls a transistor 26 by this voltage difference. A feedback circuit 25 is provided at the input and output of the operational amplifier 24 to improve startup characteristics and prevent hunting.

A power supply voltage is connected to one end of the motor coils 27 to 30 via a current limiting resistor 42, and the other end is controlled by transistors 31, 35, 37, and 39, respectively. A Hall element 34.38 for controlling the base current is connected to the base of each transistor 31.35°37.39, and the current applied to these is connected to the base of the transistor 26.
controlled by Each Hall element 34.38 is connected via a protective resistor 32.33.36.

Conventionally, one or more configurations have been used to control the rotational speed of the magnetic disk to be constant according to the detected rotational speed.

In the conventional configuration shown in FIG. 3, the motor coils 27 to 30
The maximum voltage applied to the motor is always the power supply voltage vl both at startup and during steady rotation. Resistor 42 connects coils 27, 28, 29 .
The current flowing through the circuit 30 is limited.

This is especially designed to reduce the coil current during steady rotation and prevent heat generation, but on the other hand, at startup, this resistance 4
2, the starting current is limited and the starting torque is sacrificed.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, in a motor control method in which an electric motor is started and rotated at a predetermined rotation speed, A configuration is adopted in which current control means is provided to increase the current supplied to the coils of the motor compared to the steady rotation period.

[Operation] According to the above configuration, the starting torque can be increased by increasing the current applied to the coil of the motor during the motor starting period compared to the steady rotation period.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings. However, in the following, the same reference numerals will be given to the same or corresponding members as in the conventional example, and detailed explanation thereof will be omitted.

FIG. 1 shows the structure of a control system for a spindle motor of a magnetic disk drive employing the motor control method of the present invention.

As shown in the figure, a tacho generator 13, an amplifier AMP,
Mono multivibrator MM, Op.

24, Hall element 34.38, transistor 31.3
The motor rotation speed control system according to 3.37.39 is constructed exactly the same as that shown in FIG.

However, power is supplied to the motor coils 27, 28, 29, 30 through a control circuit consisting of a transistor 41 and a current limiting resistor 42 connected in parallel as in the prior art. A timer 20 composed of a mono-multivibrator or the like is connected to the base of the transistor 41, and a motor-on signal is inputted to the timer 30 from a terminal 43.

In the present invention, a circuit including a timer 40, a transistor 41, and a starting signal 43 for turning on the motor is attached to the conventional circuit (see FIG. 3) as shown in FIG. The timer 40 is activated, and for a time determined by the timer, the transistor 41 is conductive, allowing a large current to flow through the coils 27 to 30, and generating a large starting torque.

On the other hand, after the timer expires, the transistor 41 is cut off and power is supplied via the resistor 42 as before, so current is limited and heat generation during the steady rotation period can be minimized.

The above configuration can also be modified as shown in FIG.

In FIG. 2, a voltage v2 higher than the power supply voltage v1 is applied to the coils 27 to 30 of the motor at the time of startup.

That is, the resistor 42 is omitted, and the power supply voltage v2, which is higher than Vl, is connected to the collector of the transistor 41 in FIG. 1 via the terminal 44.

A diode 47 connects the connection point between the transistor 41 and the coils 27 to 30 to the vl power supply line.

When the motor-on signal is input to the terminal 43, the timer 40 operates in synchronization with this, and the transistor 41 becomes conductive for a time determined by the timer, during which time the voltage applied to the motor coil becomes the normal voltage. The voltage v2 becomes higher than v1. At this time, the current flowing through the motor coil also increases,
As in the first embodiment, the starting torque can be increased.

In FIG. 2 as well, the transistor 41 is cut off after the time set by the timer 4o has elapsed, and the voltage Vl during steady rotation is applied via the diode 47, so the current is limited and the effect of preventing heat generation is reduced. have

The present invention is characterized by providing a circuit for increasing the motor coil current for a certain period of time in synchronization with a motor signal, and can be applied to various motor drive circuits such as DC motors and stepping motors. Furthermore, the circuit configuration illustrated above is merely an example, and it goes without saying that those skilled in the art can adopt various modifications without impairing the technical idea of the present invention.

[Effects of the Invention] As is clear from the above, according to the present invention, in a motor control method in which an electric motor is started and rotated at a predetermined rotation speed, the electric motor is supplied to the coil of the motor for a predetermined period of time from the start of the motor. Since the structure includes a current control means that increases the current generated during the steady rotation period compared to the following steady rotation period, the starting torque is increased by supplying a larger current than the steady rotation period at startup, and the heat generation during the steady rotation is reduced. An excellent effect is that the starting characteristics of the motor can be significantly improved without causing problems such as increase.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the configuration of a motor control circuit adopting the motor control method of the present invention, Fig. 2 is a circuit diagram showing a modification of the configuration of Fig. 1, and Fig. 3 is a circuit diagram showing a conventional motor control circuit. FIG. 2 is a circuit diagram showing the configuration of a circuit. 2~1O532,33,36,42...Resistance 12.1
4,17.2o,47-...Diode 15.18,2
1.26.31.35.39... Transistor 41... Transistor 16.19.22... Capacitor 13... Tacho generator 24... Operational amplifier

Claims (1)

[Claims] In a motor control system in which an electric motor is started and rotated at a predetermined rotation speed, current control means is provided for increasing the current supplied to the coil of the motor for a predetermined period of time from the start of the motor compared to the following steady rotation period. A motor control system featuring: