JPS61285095A - Counterelectromotive force controller of dc motor - Google Patents

Abstract

PURPOSE:To simplify a counterelectromotive force controller by obtaining a value corresponding to the counterelectromotive force in an input unit of a counterelectromotive force regulator. CONSTITUTION:An armature voltage Ea is input through an input filter 73 having the same time constant as an armature time constant Ta, an armature current Ia is converted by a voltage divider 74 to a value corresponding to the voltage drop Ia.Ra at an armature resistor Ra, and input through an input resistor 75. Accordingly, the combined value Vin in the input unit of a counterelectromotive force regulator 7 corresponds to a counterelectromotive force detected through a filter having the time constant Ta. The regulator 7 compares the counterelectromotive force corresponding value obtained in this manner with a command value Eomega*, and applies a current command value to a current regulator.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a back electromotive force control device for a DC motor, which includes a back electromotive force regulator for making the back electromotive voltage match a command value.

[Conventional technology]

This type of back electromotive voltage control device is applied, for example, to one that performs variable speed control of a DC motor using a back electromotive force as a representative value of rotation speed without a tacho generator. An example is shown in FIG. In this figure, 1 is a DC motor, the armature of which is supplied with power from an AC power source via a thyristor converter 2. 3 is a field adjuster. The control input for the firing angle regulator 4 of the thyristor converter 2 is provided by an armature current regulator 5. The current regulator 5 functions to match the armature current detected via the alternating current generator 6 and a rectifier circuit (not shown) to a current command value. This current command value is given by the back electromotive force regulator 7. The back electromotive force regulator 7 receives a command value derived from the speed setting device 9 via an acceleration/deceleration calculator 8 on one side, receives a value equivalent to the back electromotive force on the other hand, and adjusts the back electromotive voltage to that command. It works to match the value. The back electromotive voltage is calculated by a back electromotive force calculator provided as an accessory to the regulator 7 from the detected value of the armature voltage from the DC voltage detector 11 and the detected value of the armature current. FIG. 3 shows a specific example of the back electromotive force calculator 10 attached to the back electromotive force regulator 7. The back electromotive force calculation unit 10 is composed of a calculation amplifier A1, and the detected value of the armature voltage E is input to the input filter unit 101.
The detected value of the armature current (2) is input to the proportional differentiation circuit section 102. This is the basic formula for the back electromotive force Eω in the armature circuit of a DC motor: Eω=Ea − (Ra + 5 Lm') 1m
---- Based on (1). However, R1 is armature resistance, Ll is armature inductance, and S is Laplace operator. The output of the back electromotive voltage calculator 10 is inputted to the operational amplifier 2 which constitutes the back electromotive voltage regulator 7 via the filter section 71 . Command value Eω0 is input via input resistor 72.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a means for easily determining a back electromotive voltage by omitting a special back electromotive force calculator required in the conventional technology.

[Means to solve the problem]

According to the present invention, the above object is to introduce a signal proportional to the armature voltage and the armature circuit voltage drop to the back electromotive force regulator, in addition to its command value input, as an actual value human power to be compared with it. This is achieved by providing a first-order lag filter having a time constant equal to the armature circuit time constant at the input terminal to which the armature voltage is introduced.

[Effect]

The present invention is based on the above basic formula (1). That is, if the armature circuit time constant is T1, then T,=L,/
R. Therefore, equation (1) can be transformed as follows. Therefore, the left side corresponds to the actual value input composite value at the input part of the back electromotive voltage regulator in the present invention. On the other hand, the right side can be regarded as a value obtained by passing the back electromotive force Eω through a detection filter with a time constant T. Therefore, the composite value of the actual value inputs at the input of the back electromotive force regulator corresponds to the value obtained by passing the back electromotive force Eω through the detection filter with the time constant T1. In this manner, according to the present invention, a value equivalent to the back electromotive voltage detection value is obtained at the input section of the back electromotive force regulator, so that a special back electromotive voltage calculator in the prior art is not required.

【Example】

FIG. 1 shows the main parts of an embodiment of a back electromotive force control device according to the present invention. In FIG. 1, A2 is an operational amplifier constituting a back electromotive force regulator as in FIG. 2. A command value Eω'' is introduced to this operational amplifier via an input resistor 72 as in FIG. 2.The armature voltage E1 (detected by the DC voltage detector 11 in FIG. 1) is The armature current 1. (detected by the current transformer 4 and attached rectifier in FIG. It is converted into a voltage drop equivalent to R1·I3 in the resistor R1 and inputted via the input resistor 75. Therefore, the composite value V in at the input part of the back electromotive force regulator 7 can be expressed as follows. The second term corresponds to Eω 1 + s T m , that is, it corresponds to the back electromotive force Eω detected through the filter having a time constant of T1. The value corresponding to the back electromotive force generated is compared with the command value Eω", and the resulting control deviation is subjected to a predetermined adjustment calculation (for example, a proportional integral calculation), and is then applied to the minor loop current regulator 5 (Fig. 1). Gives the current command value.

【Effect of the invention】

As described above, according to the present invention, the back electromotive voltage can be detected easily at the input part of the back electromotive voltage regulator via the detection filter having the time constant T, without using a special back electromotive force calculator. A value corresponding to the back electromotive force is obtained. Therefore, it is possible to simplify the back electromotive voltage control device and reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a main part of an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional example of a back electromotive voltage control device, and FIG. FIG. 3 is a circuit diagram showing a specific example of an electromotive voltage regulator portion. 7-Back electromotive force regulator, 73-・Input filter, 74...
...-voltage divider, E6)*, -speed command value (back electromotive force command value), Eω... -back electromotive force, E, -armature voltage, ■,
--- Armature current, R, --- Armature resistance. Fang 3＠ 〉 ＼、− 1Φ′

Claims (1)

[Claims] 1) In a back electromotive force control device for a DC motor, which is equipped with a back electromotive voltage regulator for making the back electromotive voltage match a command value, the back electromotive voltage regulator is provided with the following: Then, a signal proportional to the armature voltage and the armature circuit voltage drop is introduced as an actual value input to be compared, and the input terminal from which the armature voltage is introduced has a time constant equal to the armature circuit time constant. 1. A back electromotive force control device for a DC motor, characterized in that a first-order lag filter is provided.