SU1713068A1 - Method of controlling dc motor torque - Google Patents

Abstract

The invention relates to electrical engineering and can be used in a control system of direct current electric drives. The aim of the invention is to improve the accuracy of torque control. A device that implements a method for controlling the torque of a DC motor of sequential excitation contains a nonlinear torque controller 1, the output of which is connected to the input of converter 18, the regulation of the dynamics of the electric drive is determined by the first order linear differential equation by introducing two multipliers into the nonlinear regulator 1 of torque 11 and 13 and two functional converters 6 and 10. 2 ill.

Description

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with

The invention relates to electrical engineering and can be used in control systems of direct current electric drives.

The purpose of the invention is to improve the accuracy of torque control.

FIG. 1 shows a functional diagram of a control unit that implements this control method; in fig. 2 is equivalent linear model.

The direct current motor control unit contains a nonlinear moment regulator 1 consisting of the first amplifier 2, at input 3 of which a reference voltage is applied, the output of the first amplifier 2 is connected to the first input of the first adder 4, the output of which is connected to the input of the second the amplifier 5, the first functional element 6, the first input of which is connected with the output of the second amplifier 5, and the output with the first input of the second adder 7, the third adder 8, the first input of which is connected with the output of the second totalizer and 7, and the third amplifier 9, the output of which is connected to the second input of the third adder 8, and to the input of the third amplifier 9, which is connected to the input of the second functional element 10, the second input of the first initial element 6 and the input of the first multiplier 11, is fed the current signal 12 core, the output of the second functional element 10 is connected with the third input of the first functional element 6, the second input of the first multiplier 11 and the first input of the second multiplier 13, the output of the first multiplier 11 is connected to the input of the fourth amplifier 14, the output the signal of which is fed to the second input of the first adder 4, the second input of the second multiplier 13 is given a signal 15 of the rotational speed of the direct current motor, the output of the second multiplier 13 is connected to the input of the fifth amplifier 1.6, the output of which is connected to the second input of the second adder 7. Since Because the voltage supplied by the nonlinear torque control is not enough to control the motor, it is necessary to introduce a converter with a gain CRF. One, in order to match these two voltages, it is necessary to enter a link with a factor before the converter

1 / CRC.

The output signal 17 of the non-linear torque controller 1 is fed to the input of the converter 18, the output signal 19 of which, namely the voltage Ufl (t), is applied to the motor 20.

The device works as follows.

The equation of the dynamics of a DC motor with sequential excitation is:

and 1 V + - „- +

+ WB + KF () nd), (1)

where and is the voltage applied to the engine;

1 - engine current circuit current;

P 2 is the total resistance of the core chain;

 total inductance of the root winding;

WB is the number of turns of the field winding; /

F (1) is the motor flow, which is a nonlinear function of the current in the core;

K - engine design factor;

O) - angular speed of the engine.

The moment developed by the engine is determined by the equation;

);

and 1 H + (1 g +

.w.,

d 1

dt

An analysis of equation (3) allows us to conclude that the inductance of the core circuit (1 2- + W, coefficient

The Q-FO) varies due to the saturation of the magnetic system, therefore the time constant of the core chain, defined as

T (i) L, + ,,

The back EMF E KF (motor torque MK-F (1)) are nonlinear functions of the current in the core.

Differential equation (2), written relative to the engine torque has the form;

.,. dФJVl

dM dt

(Ht

dt

X 1 + F (1)).

Claims (2)

(4) From equation (3), they find -; - and are substituted in (4) + W F (O U1 V dt + in,, JX x (and -1 -K 2: -KF (1) d)); К (1) х х (и - Р у-КФ (1) су), (6) (1) - 1 + Ф (): Ti xa., + Wl iJ l non-linear coefficient. DM 1 / .. (Ms-M) - (Km Wem - KO (1) 1). Where T is equivalent to the constant time of regulation of the moment; Km is the coefficient relating the given moment of M3 to the voltage of the EME. Equation to the right of Eq. (6) and (8), get the control law and (d) (Mz-M) (K V9 (ifl)) + + 1 Р 2. + KF (1) yL Thus, if a voltage is applied to the motor, varying in time in accordance with (9), then the moment dynamics is determined by the linear first-order differential equation (8). 1 In the initial position, the voltage 19 of the converter 18 is equal to O, therefore the core current and the rotational speed of the DC motor 20 are also 0. When a input signal is received at input .3, a signal is formed that is proportional to a given moment Мз UMS-USM Km . 5 10 15 20 25 30 35 45 ° 55 Since at the initial moment of time the signal 12 of the current cor and the signal 15 of the rotation speed are zero, there are also no signals at the outputs of elements 14, 16, 10 and 9. The UMS signal passes through the adder 4 and is fed to the input of the amplifier 5, the output of which forms the signal UMS /, which is fed to the first input of the functional element b, and there are no signals at the other two inputs at this time. Since function X) is equal to O, then ()) 00, a signal is generated at the output of functional element 6, the amplitude of which depends on the design and circuit of element 6 (in the case of operational amplifiers, the amplitude of the output signal is equal to the power supply voltage of operational amplifiers). The output signal of the element 6 passes through the adders 7 and 8 unchanged and is fed to the input of the converter 18. Since in this case the gain of the converter is chosen equal to one, the input voltage 19 of the converter 18 is applied to the motor 20. The engine 20 begins to rotate, therefore The signal 12 of the current core and the signal 15 of the speed of the engine 20 are different from zero. A signal appears at the output of the functional element 10. At the output of the amplifier 14, a signal of the moment named K-FO) -1 appears. This signal is applied to the second input of the adder 4, at the output of which a signal Ui is generated, named after UsM (KMF). This signal passes through the amplifier 5 and enters the input of the functional element 6. Since the two other inputs of this element receive the signals 12 of the current core and the signal from the output of the functional element 10, the output of the element 6 generates a signal u2 (meas-Km-KFO) 1 ) (Qu (1)) (13)) -function, defined in (7). The signal U2 is fed to the first input of the accumulator 7, the second input of which is supplied by the motor EMF signal, formed with the power of the second multiplier 13 and the amplifier 16 in the form of EE to FO-RF Ud. 1) -YX x (K95 ()) + QF) (M. This signal is fed to the first input of adder 8, to another input of which a signal is output from the output of amplifier 9, defined as UR - K. At the output of adder 8, a signal is generated which, via converter 18, is applied to motor 20. Thus, a voltage is formed at which the The torque pattern is determined by the first-order linear differential equation (8). The method allows to control the torque with high accuracy and greatly simplifies control. Formula of the invention A method for controlling the torque of a DC motor of sequential excitation, at which the current of a corona circuit is measured, the difference between the set and the actual moments of the engine and form a control voltage applied to the engine, o t and the fact that, in order to improve the accuracy of torque control, in addition, the engine's anti-electromotive force is determined, the motor flux, the instantaneous value of the inductance of the core circuit, as a function of the core current, and the control voltage are formed as the sum of three terms, the first of which is the motor counter-electromotive force, the third is determined in accordance with the ratio of ФF (i) U (t) - (M3-M) - (KLC gij 1 + -HF (l)) (L, + We- (l) -) where M3 is the specified moment; M-real moment; t is equivalent to the time constant of torque control; K - engine design factor; FD) - engine flow; 1 - current of the root circuit; dФ (i) - у .-- is the instantaneous value of the inductance of the core chain; total inductance of the core chain; WB is the number of turns of the field winding. cfius.Z