SU1119149A1 - Process for dependent adjusting of excitation current of d.c.motor - Google Patents

Abstract

A METHOD FOR DEPENDENT CONTROL OF CURRENT EXCITATION OF A DC MOTOR ELECTRIC MOTOR, according to which the core current of the electric motor and the EMF value are determined, the EMF value is compared with its nominal value and when the second value exceeds the second value, the motor excitation current is reduced while simultaneously increasing its motor speed. that, in order to improve the commutation of the electric motor by reducing the emission of the braking current when reversed across the field, determine the mode of operation of the electric motor In the brake mode, the magnitude of the current of the core is compared with the specified allowable value of the B4 value, and when the current of the core exceeds the specified value, the setting of the excitation current is reduced by a constant value.

Description

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The invention relates to electrical engineering, namely to DC motor drives with two-zone control.

There is a known method of independent control of the excitation flow, according to which the voltage on the motor cortex is controlled to a certain 5f6vn control signal, and then the excitation flow (current) of the electric motor is changed using main feedback at the rotation frequency or auxiliary control feedback in the loop control of the excitation flow IJ.

A voltage-independent change in the motor crust in the braking conditions causes overvoltage and an increase in the braking current.

The closest to the proposed technical essence and the achievable result is the method of dependent control of the excitation current of the DC motor, according to which the magnitude of the core current of the motor and its EMF value is determined, the EMF value is compared with its nominal value and when the first value is reduced to the second, the task is reduced motor current at the same time limiting the rate of its rise.

When using this method in the case of a deep weakening of the floor of the electric motor and the presence of large flywheel masses on the motor shaft, the converter in the core circuit can become saturated, output. the EMF sensor signal ceases to increase, c. As a result, the EMF and braking current increase in excess of the allowable values, which leads to deterioration of the electric motor commutation.

The purpose of the invention is to improve the switching of an electric motor by reducing the TOifMoaiforo current emission during reverse across the field.

The goal is achieved by the fact that, according to the method of dependent control of the excitation current of a direct current electric motor, which is used to determine the magnitude of the main current of the electric motor and the magnitude of its electromotive force, the emf value is compared with its nominal value and when exceeded by the first value

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the second reduces the setting of the excitation current of the electric motor while simultaneously limiting the rate of its growth, determines the operating mode 5 of the electric motor, compares the magnitude of the current of the core with a predetermined allowable value in braking mode and reduces the setting of the current of the excitation by a constant value when the current of the core exceeds the specified value.

Figure 1 shows the functional diagram of the device; figure 2 - timing diagrams.

The device contains a series-connected regulator 1 of rotational speed and regulator 2 of the main current in the control circuit of an irreversible converter 3, connected to the electric motor core 4, the current sensor 5 of the core, the excitation current control system 6 in the control circuit of the reverse valve converter 7, supplying the winding 8 excitation of electric motor.

The output of the current sensor 5 and the output of the voltage source 9 is connected to the inputs of the relay element 10, the output of which is connected to the excitation current control system 6.

To implement the method, the level of the reference voltage UQ, which determines the allowable value of the core current, is set, as a rule, proportional to the starting current of the core. In the braking mode, the current cor is equal to I g2.J where the emf can be pre-.

max out the rectified voltage of the U converter,

0, which is accompanied by current surges (Fig. 2), if the converter in the core circuit enters saturation when regulating the excitation current as a function of the EMF (in this mode in

5 voltage converter functions).

When implementing the proposed method, the voltage is compared, pro-.

0 is a portion of the braking current with the reference voltage, and as soon as the first one exceeds the second, with the help of the relay element 10 a signal is generated and fed to the control system

5 by excitation, thereby limiting the rate of increase of the excitation current after its reversal, i.e. stabilize the brake directly

Claims (1)

METHOD FOR DEPENDENT CONTROL OF EXCITING ELECTRIC MOTOR OF CURRENT CURRENT, according to which determine the magnitude of the current of the armature of the motor and the magnitude of the EMF, compare the magnitude of the EMF with its nominal value and when the first value is exceeded, the second set the excitation current of the electric motor while limiting the rate of its rise, which is different in order to improve the switching of the electric motor by reducing the emission of braking current when reversing the field, determine the mode of operation of the electric motor, in in braking mode, compare the value of the armature current with a predetermined permissible value and, when the armature current exceeds a preset value, reduce the reference of the excitation current by a constant value *.