JPH0556678A - Motor driver and controller - Google Patents

Abstract

PURPOSE:To enable the variable speed control of a motor over a wide revolution continuous range by controlling the motor so that it may decelerate or accelerate according to the revolution of a motor. CONSTITUTION:In the case of controlling the revolution of a motor 1 so that it may decelerate or accelerate continuously, the threshold is set at the value before the temperature of the junction of a semiconductor, which constitutes the drive circuit of the motor 1, reaches such operating condition that it becomes an allowable temperature. And when the operating condition becomes a threshold value, the drive voltage to be applied to the drive circuit 2 of the motor 2 is changed over to the drive voltage by which the rotational speed is higher than the control target speed at that time within the range of the temperature of the semiconductor junction not exceeding the allowable temperature. Hereby, the variable speed control of the motor 1 can be performed over the wide rotation continuous range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive control device for controlling a motor so as to continuously decelerate or speed it up.

[0002]

2. Description of the Related Art A magnetic recording / reproducing apparatus (hereinafter referred to as "VT
An example will be described of the fast-forwarding and rewinding (hereinafter referred to as "fast-forward") operation of the magnetic tape in "R". FIG. 6 is a block circuit diagram showing an example of the configuration of the motor drive control device. 1 is a motor, 2 is a rotation speed detection head that generates a pulse signal according to the rotation speed N of the motor 1, and 5 is a control of the motor 1. A microcomputer that stores patterns and the like and sends switching signals 1 and 2 for control, 6 is a servo circuit that sends a rotation speed control voltage according to a control reference signal to the drive circuit 2, and 7 is a speed of the magnetic tape. depending pulse signal (CTL signal) magnetic tape speed detecting head for generating a driving power source 8 switches a, 9 to switch the control reference signal input to the servo circuit 6 outputs a normal voltage V _L and the high voltage V _H Reference numeral 10 is a switch B for switching the drive voltage V _m applied to the drive circuit 2.

Conventional VTR fast-forwarding is performed by switching the rotation speed control voltage, or in addition, by switching the drive voltage before and after the high-speed operation to obtain higher-speed magnetic tape feeding.

As an example of a conventional fast-forward control pattern,
There is a means for controlling the rotation speed of the motor based on the frequency of the (CTL signal) recorded on the magnetic tape.

FIG. 7 is a characteristic diagram showing a change in the rotation speed of the motor 1 by the control means. The horizontal axis represents the winding diameter of the reel in the magnetic tape cassette, that is, the amount of the magnetic tape wound on the reel. The vertical axis in FIG. 7A shows the drive voltage V _m applied to the drive circuit 2, the vertical axis in FIG. 7B shows the rotational speed N of the motor, and the vertical axis in FIG. Indicates the temperature T _j of the semiconductor junction (hereinafter referred to as “semiconductor junction”) in the drive circuit 2.

Next, the operation will be described. Assuming that a constant drive voltage V _H is applied to the motor 1 as shown in FIG. 7A, the winding amount per one rotation of the motor 1 increases as the reel winding diameter changes. , The control target rotation speed of the motor 1 gradually decreases as shown in FIG. 7 (b).

As described above, when the rotation speed is reduced under the constant drive voltage V _H , the counter electromotive voltage of the motor 1 is reduced and the heat generation amount P _w at the semiconductor junction is increased. The heat generation amount P _w and the temperature T _j of the semiconductor junction are (1)
It is represented by the formula and the formula (2).

P _w = (V _m -K _e · N-R · I) · I (1) T _j = θ · P _w ··· (2) where V _m : drive voltage K _e : motor Back electromotive force constant N: Motor rotation speed R: Motor coil resistance I: Motor load current θ: Thermal resistance from semiconductor junction to semiconductor package

When the rotational speed N of the motor decreases under a constant load, the term of K _e · N (back electromotive force) in the equation (1) becomes small, and as a result, the value of the heat generation amount P _w becomes large. Further, from the equation (2), the temperature T _j of the semiconductor junction portion rises as shown in FIG. 7C as the heat generation amount P _w increases.

FIG. 3 is a diagram showing the relationship between the rotational speed N of the motor and the temperature T _j of the semiconductor junction, that is, the temperature T of the semiconductor junction.
_The upper limit temperature T _{max of j} is specified in terms of the operational reliability of the semiconductor element, and is normally used within the allowable temperature T _{L which is} lower than the upper limit temperature T _max in consideration of derating.

[0011]

Since the conventional motor drive control device controls the rotation speed of the motor so that the speed of the magnetic tape becomes constant, the winding diameter of the take-up reel approaches the end of winding the magnetic tape. Becomes larger, the speed of the motor decreases, the back electromotive voltage of the motor 1 decreases,
There is a problem that the amount of heat generated in the semiconductor junction increases, the temperature T _j of the semiconductor junction exceeds the allowable temperature T _L , and the semiconductor is destroyed.

If the drive voltage V _{m of the} motor is easily switched, the rotation speed changes abruptly depending on the rotation speed when the drive voltage is switched, and the magnetic tape is slackened or excessive tension is applied to the magnetic tape. There is a problem that the tape may be damaged.

The present invention has been made to solve the above problems, and by switching the drive voltage V _m at an appropriate timing, a rapid change in the rotation speed at the time of switching the drive voltage does not occur, And the temperature T of the semiconductor junction
_The object is to obtain a motor drive control device that can be used within a range in which _j does not exceed the allowable temperature T _L.

[0014]

In a motor drive control device according to the present invention, in a motor in which the magnetic tape speed is controlled to be a constant speed, the control target rotation speed is continuously changed as the reel diameter changes. Therefore, in the case of deceleration control, the speed is lower than the original drive voltage before the rotational speed exceeds the temperature T _j allowable temperature T _L of the semiconductor junction in the drive circuit, and the control target at that time is set. Switch to a drive voltage that provides a rotation speed that is faster than the rotation speed, and in the case of speed-up control, switch to a drive voltage that is higher than the original drive voltage and that is faster than the control target rotation speed at that time. It is equipped with means.

[0015]

Since the motor drive control device according to the present invention switches to the drive voltage capable of maintaining the control target rotation speed at an appropriate timing according to the rotation speed of the motor, there is no sudden change in the rotation speed of the motor, and It is possible to drive the motor such that the temperature T _j of the semiconductor junction does not exceed the allowable temperature T _L and continuously decelerates or accelerates in a predetermined pattern.

[0016]

EXAMPLES Example 1. An embodiment of the present invention will be described below. The configuration of this embodiment is the same as that of the conventional example shown in FIG. 6, but the control operation by the microcomputer 5 is different. FIG. 1 is a flowchart of the control operation. FIG. 3 is a characteristic diagram showing the relationship between the rotation speed N and the temperature T _j of the semiconductor junction, and shows that the temperature T _j of the semiconductor junction increases as the rotation speed N decreases.

FIG. 4 is a characteristic diagram showing the relationship between the drive voltage V _m and the rotation speed N, showing that the controllable rotation speed range expands as the drive voltage V _m increases. It can be seen from FIG. 4 that the temperature T _{j of the} semiconductor junction increases as the driving voltage V _m increases.

Next, the operation of this embodiment will be described with reference to FIGS.
Will be described. As described in the conventional example, in FIG. 2, the reel winding diameter increases with the passage of time, and the control target rotation speed decreases, but in this embodiment, the drive is performed when the rotation speed reaches N _X. the voltage V _m, is switched from V _H to V _L.

This operation will be described with reference to the flowchart of FIG. First, in step 1 (hereinafter referred to as "S1"), the magnetic tape winding operation is started, and in S2, control is performed so that the frequency of the CTL signal reproduced from the magnetic tape becomes constant, and in S3, the changeover switch B Sets the drive voltage V _m to the high voltage V _H.

Thereafter, in S4, the drive voltage switching rotational speed N _X
(See FIG. 2 (b)) is used as a threshold value to enter a loop for monitoring the rotation speed N, and when the rotation speed N becomes equal to or lower than N _X , the switch B is switched to the drive voltage V _L side in S5 to switch the motor. The drive operation is continued, and the motor is stopped when the magnetic tape reaches the end in S6 or when a stop command is received.

Next, an example of setting the threshold value N _X for switching the drive voltage V _m will be described with reference to FIGS. 2, 3 and 4. As shown in FIG. 2B, as the rotation speed N decreases with time, the temperature T _j of the semiconductor junction moves to the left on the characteristic curve of FIG. 3, and the rotation speed N _L If the temperature is below, the temperature T _j of the semiconductor junction will exceed the allowable temperature T _L.

On the other hand, considering the drive voltage V _m required when the rotation speed N becomes low in FIG. 4, the rotation speed N becomes
When it is N ₁ or less, it is in the rotational speed range that can be controlled by the drive voltage V _L. Thus the timing of switching the driving voltage V _m, when the rotational speed N _X is in the range _{N L <N X <N 1} , if switch the driving voltage V _m from V _H to V _L, control out like rotational speed It is possible to perform smooth continuous deceleration control without fluctuation of the rotation speed due to, and it is possible to suppress the temperature T _j of the semiconductor junction to _TL or less.

Example 2. In the above embodiment, the smooth continuous deceleration control is described, but the invention can be similarly applied to the continuous speed increase control as shown in FIG. That is, when the drive voltage V _m is switched, if the drive voltage is switched from V _L to V _H at the threshold N _X ,
Without changing the rotation speed due to loss of control,
The smooth continuous speed-up control can be performed, and the temperature T _j of the semiconductor junction can be suppressed to _TL or less.

Example 3. In the above embodiment, the example in which the drive voltage V _m is switched once at the time of deceleration or acceleration has been described. However, when the range of change in the rotational speed to be controlled is wide, a plurality of drive voltage switching rotational speeds N _Xi are set, By sequentially switching the drive voltage V _m , the same effect as in the above embodiment can be obtained even when the control rotation speed range is wide.

Example 4. Further, in the above embodiment, the case has been described in which the fast-forward speed of the magnetic tape is controlled to a constant speed with reference to the frequency of the CTL signal recorded on the magnetic tape. However, other rotation speeds are continuously changed. The same effect can be obtained by applying it to the system using the control means.

Example 5. Further, in the above embodiment, the example in which the rotation speed of the motor is used as the threshold value for switching the drive voltage has been described. However, the temperature T _j of the semiconductor junction portion of the drive circuit is detected and compared with the allowable temperature T _L. , T _j < _TL , and the drive voltage V _m is switched at the timing at which the condition of N _X <N ₁ is satisfied, the same effect as in the above embodiment can be obtained.

[0027]

As described above, according to the present invention, when controlling the rotational speed of the motor so as to continuously reduce or increase the speed, the temperature T _j of the semiconductor junction forming the drive circuit of the motor is controlled. A threshold value is reached before the operating condition at which the operating temperature reaches the allowable temperature T _L is reached, and the drive voltage applied to the drive circuit of the motor when the operating condition reaches the threshold value is set to the temperature T of the semiconductor junction. _The motor is driven so that the rotation speed by the drive voltage after the switching is within a range in which _j does not exceed T _L , and the rotation speed that is higher than the control target speed at that time is obtained. The temperature T _j of the semiconductor junction portion in the circuit can be kept below T _L at all times, and a sudden change in the rotation speed of the motor due to the switching of the drive voltage can be prevented.
There is an effect that a motor drive control device capable of performing variable speed control of a motor over a wide continuous rotation range can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart of a drive voltage switching control operation according to an embodiment of the present invention.

FIG. 2 is a diagram showing changes in drive voltage, rotation speed, and semiconductor junction temperature in this example.

FIG. 3 is a diagram showing a relationship between a temperature of a semiconductor junction and a rotation speed.

FIG. 4 is a characteristic diagram showing a relationship between a motor rotation speed and a drive voltage.

FIG. 5 is a diagram showing changes in drive voltage, rotation speed, and semiconductor junction temperature according to another embodiment of the present invention.

FIG. 6 is a block circuit diagram showing a motor drive control device according to an embodiment of the present invention and a conventional example.

FIG. 7 is a diagram showing changes in drive voltage, rotation speed, and semiconductor junction temperature in this conventional example.

[Explanation of symbols]

 1 Motor 2 Drive Circuit 4 Rotational Speed Detection Head 5 Microcomputer 6 Servo Circuit 7 Magnetic Tape Speed Detection Head 8 Changeover Switch 9 Drive Power Supply 10 Changeover Switch

Claims (2)

[Claims] 1. A motor drive control device for controlling a motor rotation speed so as to continuously decelerate or speed up in a constant pattern, and a means for detecting the motor rotation speed, and the detected rotation speed. Is a predetermined threshold value, the drive voltage of the motor is lower than the original drive voltage in the case of deceleration control, and a drive voltage that gives a rotation speed faster than the control target rotation speed at that time. In the case of acceleration control, it is higher than the original drive voltage,
A motor drive control device further comprising: a means for switching to a drive voltage at which a rotation speed higher than the control target rotation speed at that time is obtained. 2. A motor drive control device for controlling a motor rotation speed to continuously decelerate or speed up in a constant pattern, wherein the temperature of a junction of semiconductor elements constituting a circuit for driving the motor is controlled. The means for detecting and the drive voltage applied to the drive circuit when the detected temperature of the semiconductor junction portion reaches a predetermined temperature are lower than the original drive voltage in the case of deceleration control, and Switch to a drive voltage that gives a rotation speed faster than the control target rotation speed, and in the case of speed-up control, a drive voltage that is higher than the original drive voltage and that is faster than the control target rotation speed at that time. And a means for switching to a motor drive control device.