JPS606762Y2 - Field magnetic flux detection device for DC motor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a field magnetic flux detection device for a DC motor that detects the field magnetic flux of a DC motor with high precision.

FIG. 1 shows a conventional field magnetic flux detection circuit, in which a field current If is detected by a current detector 3 connected in series with a field winding 2 of a DC motor 1, and a function generator 4 is used to detect the field current If. The field magnetic flux signal Φ with respect to the field current If is determined.

The function generator 4 generally generates a function such that as the field current If increases, the output, that is, the rate of increase in the field magnetic flux signal Φ decreases due to saturation, as shown in FIG. This function is created using the polygonal line approximation method.

However, in reality, the field magnetic flux signal Φ with respect to the field current If of the DC motor cannot be accurately detected by this method because the DC motor is affected by hysteresis of magnetic flux changes, armature reaction, etc.

Therefore, if the field magnetic flux signal of a DC motor is detected using a simple function generator as described above, an automatic control device that uses this signal, for example, can detect the field magnetic flux of a DC motor and calculate its torque. However, in a direct current motor for driving a tandem rolling mill that performs tension control, there is a drawback that the desired control accuracy cannot be obtained.

In order to improve control accuracy, the present invention is designed to accurately detect the field magnetic flux of a DC motor without being affected by hysteresis of field magnetic flux changes, armature reaction, etc. It is an object of the present invention to provide a field magnetic flux detection device for a DC motor that can be used.

The present invention will be explained below based on an embodiment shown in FIG.

FIG. 3 is a block diagram of the field magnetic flux detection device of the present invention, in which the terminal voltage V of the DC motor, the armature current 11 and the rotation speed N are used as input signals.

The terminal voltage signal V is led to the middle terminal which is one input terminal of the adder 11, and the armature current signal I is led to the voltage drop calculation circuit 10.
The signal is then led to one terminal, which is the other input terminal of the adder 11, and the difference between the two signals is determined.

The output e of the adder 11 is then led to a divider 12, where it is divided by the rotational speed signal N and the field magnetic flux signal Φ is taken out as an output.

The field magnetic flux Φ of a DC motor is generally expressed as follows.

Here, k is a constant determined by the structure of the DC motor armature, the number of magnetic poles, etc., ■ is the DC motor terminal voltage, ■ is the DC motor armature current, and R is the total resistance including the brush contact resistance of the DC motor armature circuit. The resistance, L is the inductance of the DC motor armature, and N is the rotational speed of the DC motor.

The voltage drop calculation circuit 10 calculates 1 (IR+I, -) on the right side of equation (1) using a known first-order differential equation analog computer circuit. This is a circuit that calculates the value of voltage drop (IR+I Lat)=zz with respect to the momentary armature current.

The adder 11 has a terminal voltage signal ■ at both input terminals, and
The output of the voltage drop calculation circuit 10, that is, the voltage drop signal 2 generated by the armature current, is added with the polarity reversed, and the difference between the two signals, that is, the back electromotive force I, is the force signal e= (V-(IR+L side) ) is being calculated.

The divider 12 divides the back electromotive force signal e by the rotation speed signal N to calculate the field magnetic flux signal φ as shown in equation (1),
It is output as output.

As explained above, when the field magnetic flux detection device of the present invention is used to detect the field magnetic flux of a DC motor, in addition to the voltage drop due to the resistance component of the armature, it is also possible to detect the voltage drop due to the armature actance component. Since the correction is also performed, it is possible to detect the field magnetic flux of the DC motor with high precision, which is not affected by hysteresis of field magnetic flux changes, armature reaction, etc.

Therefore, if the proposed field magnetic flux detection device for a DC motor is used in a DC motor circuit of a tandem rolling mill that performs tension control, fluctuations in the torque of the DC motor can be accurately detected, increasing the control accuracy of tension control. be able to.

That is, it is possible to provide automatic control signals that can improve the accuracy of the shape, dimensions, etc. of products produced by the rolling mill.

[Brief explanation of drawings]

FIG. 1 is a conventional field magnetic flux detection circuit for a DC motor, FIG. 2 is an output curve diagram of a function generator, and FIG. 3 is a block diagram of a field magnetic flux detection device for a DC motor according to the present invention. 10... Voltage drop calculation circuit, 11...
Adder, 12...Divider.

Claims (1)

[Scope of utility model registration request] In a DC motor, a voltage drop calculation circuit receives the terminal voltage signal, armature current signal, and rotational speed signal as input and calculates the voltage drop caused by the armature current, and the output of the voltage drop calculation circuit and the terminal voltage signal. It consists of an adder that obtains a back electromotive force signal, and a divider that obtains a field magnetic flux signal from the output of the adder and the rotational speed signal. A field magnetic flux detection device for a DC motor, characterized in that the field magnetic flux is detected by correcting even voltage drops due to precepts.