JPH0417031B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is suitable for use in a slitting machine that cuts a wide film (for example, 4 m width) into a narrow film (for example, 30 cm width). The present invention relates to a magnet field DC motor, and more particularly to an automatic torque correction device for a permanent magnet field DC motor that automatically corrects a decrease in torque due to demagnetization of the permanent magnet.

[Conventional technology]

In the above-mentioned slitting machine, it is difficult to attach a tension detection mechanism to the winder, so it is difficult to directly detect the tension of the film. For this reason, winding control is performed by adjusting the torque of the motor by flowing an armature current necessary to achieve a preset tension.

On the other hand, a permanent magnet field direct current motor is often used as a drive motor for the winding machine due to mechanical space constraints.

FIG. 2 is a block diagram showing a conventional example of this type of torque correction device. In this figure, reference numeral 1 indicates a permanent magnet field DC motor (hereinafter simply referred to as a motor), and this motor 1 is supplied with an armature current Ia from a thyristor converter 2, and this current Ia is detected by a current detector 3. detected. The thyristor conversion device 2 rectifies the alternating current supplied from the alternating current power source 4 to form an armature current Ia, and the current
The magnitude of Ia is adjusted by changing the firing angle of the thyristor 2a using a signal supplied from the current control amplifier 5.

On the other hand, numeral 6 in the figure is a calculation device for calculating the armature current necessary to achieve the film tension set by the tension setting device 7. It is composed of a programmable controller that performs calculations. To explain further, this arithmetic device 6 includes a multiplier 6a that multiplies the tension and the winding diameter of the film to output a torque setting value Tqa, and a torque setting value Tqa.
From the torque command Tqc obtained by adding the inertia compensation value and mechanical loss compensation value to Tqa, the formula Ic = Tqc / Kφ ... (1) where φ: Field magnetic flux (Wb) K: Constant determined by the motor and an addition section 6b that calculates the current setting command Ic. Then, the current setting command Ic is manually corrected by the current correction volume 8,
A current command Iac is formed, and the firing angle of the thyristor 2a is adjusted by the current control amplifier 5 so that the armature current Ia matches the current command Iac, and feedback control of the armature current Ia is performed. .

[Problem that the invention seeks to solve]

By the way, in the conventional device described above, the permanent magnet field, that is, φ in equation (1), weakens due to excessive armature current Ia and natural demagnetization.
There was a problem that the generated torque decreased. For this reason, torque was measured periodically and the volume 8 was manually adjusted to increase the current command Iac to compensate.

However, in order to measure this torque, it was necessary to stop the machine and use many measuring instruments such as torque meters and dynamometers, as well as labor.

This invention has been made in view of the above circumstances, and aims to eliminate the need for complicated operations such as torque measurement by automatically performing torque correction.

[Means for solving problems]

In order to solve the above problems, this invention (1)
The initial value a ₀ (for example, the value at factory shipment) of the value Kφ (=Tqc/Ic) of the formula is memorized, and the above Kφ is set to the value a _o
The present invention is characterized in that the current setting command Ic in equation ( ₁ ) is automatically multiplied by a ₀ / _{a 0} when the current setting command Ic decreases to (a 0 /a ₀ ).

[Effect]

According to the above configuration, the generated torque Tqo with respect to the initial value a ₀ becomes Tqo=KφIa=a ₀ Ic (2) since Kφ=a ₀ and armature current Ia=Ic. Also, the generated torque for the value a _o after demagnetization
Since Kφ=a _o and armature current Ia=(a ₀ /a _o )Ic, Tq=KφIa=a _o (a ₀ /a _o )Ic =a ₀ Ic=Tqo ……(3) . That is, torque Tq is always kept constant.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a torque correction device according to this embodiment. In this figure, 1
A voltage detector 1 detects an armature voltage E of the motor 1, and is composed of a resistor. A rotation detector 12 detects the rotation speed of the motor 1. Here, if the armature resistance is ignored, the armature voltage E and rotation speed N are N=Ka(E/Kφ)...(4) However; since Ka is a constant, Kφ=Ka・E/N...(5) Therefore, Kφ in equation (1) can be obtained from equation (5). As mentioned above, this value Kφ gradually decreases due to the demagnetization effect, but if its initial value is a ₀ and the demagnetized value is a _o , then the actual value a _o is determined by equation (5). , _ao = Kφ = Ka・E/N ...(6). The arithmetic unit 13 calculates the value a _o using the above equation (6), and the ratio a ₀ /a _o between this value a _o and the initial value a ₀ stored in the memory 16 is sent to the dividing unit 14. It is calculated accordingly. Then, the multiplier 15 multiplies the current setting command Ic by the ratio a ₀ /a _o , and the current command Iac as follows is sent to the current control amplifier 5 as Iac = (a ₀ /a _o ) Ic ... (7) Supplied.

According to such a configuration, as already mentioned in the [Operation] section, the armature current Ia becomes (a ₀ /a _o )Ic, and the invention torque Tq of the motor 1 at this time is Tq = KφIa = a _o・(a ₀ /a _o ) Ic = a ₀ Ic = Tqo (constant) ...(8).

In this way, according to this embodiment, the armature current Ia of the motor 1 is automatically adjusted, and the torque Tq generated by the motor 1 is always kept constant.

〔Effect of the invention〕

As explained above, this invention ensures that the motor's output torque remains constant even when the permanent magnet is demagnetized, so it is possible to measure the motor torque and correct the armature current command. This has the advantage of not requiring complicated work.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a conventional torque correction device. 1... Motor, 2... Thyristor conversion device, 3
...Current detector, 5...Current control amplifier, 11...
...Voltage detector, 12... Rotation detector (3, 1 above)
1 and 12 are detection means), 13... calculation section (calculation means), 14... division section, 15... multiplication section (above 1
4 and 15 are correction means), 16...memory (storage means).

Claims (1)

[Claims] 1. In a torque correction device for a DC motor 1 using a permanent magnet as a field, the armature voltage E and the armature current of the DC motor 1 are
Detection means 3, 11 for detecting Ia and rotation speed N,
12, and the output torque Tq of the DC motor 1 and the armature current Ia are determined by the outputs of the detection means 3, 11, and 12.
The coefficient an that relates to is expressed as {an=(Ka・E)/
Calculating means 1 that calculates based on N} (Ka is a coefficient)
3, a storage means 16 for storing an initial value a0 of the coefficient an, and a storage means 16 for storing an initial value a0 of the coefficient an and the coefficient at an arbitrary point in time.
An automatic torque correction device for a permanent magnet field DC motor, comprising correction means 14 and 15 for correcting the armature current command Iac according to the ratio a0/an of the armature current command Iac.