SU1226600A1 - D.c.electric drive - Google Patents

Abstract

The invention can be used in speed control systems for electric drives having a wide range of inertia variations. The purpose of the invention is the formation of optimal speed transients when changing parameters of the electric drive. The electric drive contains an electric motor I, a converter 2, a speed controller Z. intensity indicator 4, made in the form of an amplifier-limiter 5. Introduction of an integrator 6 with a block of limitation 7, a current regulator 8 and speed and current controllers 9 and 10, a control key 1I, an integrator 12 with a reset, a module allocation module 13, a scale amplifier 14, a multiplication unit, a differentiator, 16, zero-org 17 and the restriction mode permits the sensor 18 to receive, at a fixed structure, regulators and quick-change system parameters deystvztoschie transients. The drive is invariant to changes in parameters, in particular, the moment of inertia. 3 il. c (ldd ic u: o:

Description

The invention relates to electrical engineering, in particular to direct current drives, and can be used in speed control systems for electric drives that have a wide range of inertia changes.

The purpose of the invention is the formation of speed-optimal transition processes when changing parameters of the electric drive.

FIG. 1 shows a functional diagram of the electric drive; in fig. 2 curves of transients at a speed reference jump (the current of the core does not enter the limiting mode); in fig. 3 - the same (the current cor goes to the limiting mode).

The electric drive (Fig. I) contains a electric motor 1 of constant current connected to a charged converter 2, into the control circuit of which serially connected speed controller 3 is connected, intensity set 4, made in the form of serially connected amplifier limiter 5 and integrator 6 with block 7, limitations in the feedback circuit, and a current regulator, as well as speed and current sensors 9 and 10, connected to the inputs of the corresponding regulators, respectively. In addition, it contains a serially connected controllable key 11, an integrator 12 with a reset, and a module allocation unit 13, as well as a scaled amplifier 14, a multiplication unit 15, a differentiator 16, a null organ 17, and a restriction mode sensor 18, the input of which is connected to the unit 7, and the outputs x of the control input of the controlled Katiuchi I 1, the outputs of the differentiating link 16 and the block 13 of the module's section are connected to the inputs of the multiplication unit 15, the output of which is connected via the scale amplifier 14 to the input of the intensity setting 4 An integrator 12 with a null-reset 17 is connected to the output of the differentiating link 6s, and the input of the control key 11 is connected to the output of the amplifier-limiter 5 of the intensity adjustor 4.

The drive works as follows.

In established (quasi-installed shihs) operating modes of the electric drive

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The speed reference signal 9 is equal to the signal of the motor speed sensor 9. Since the speed of the motor is non-variable,

5, the signal at the output of differentiating element 16 is zero and the null organ 17 drops the voltage of integrator 12 to zero. The output voltages of the module allocation unit 13, the blade unit 15 and the scale amplifier 14 are also zero. The average value of the voltage at the output of the amplifier-limiter 5 is zero, and the voltage at the output of the integrator 6 is equal to the voltage of the core current sensor 10 and is determined by the static load on the motor shaft. The output voltage of the regulator 8 of the core current (the structure of the regulator can be

20 PI, IlHDi or relay) is converted by controlled transducer 2 to the voltage on the core of electric motor 1.

When the signal changes

 speed (e.g., a jump) at the output of the P-speed controller, a signal appears proportional to the speed deviation from the setpoint

30 11rs Crc ();,

where K 1 - transfer coefficient

S P-regulator; speed deviation from a given value.

Wuxi limiter 5 lies at a level proportional to the maximum permissible derivative of the current core, the output signal of the integrator 6 linearly increases in time and is converted by the current regulator 8 of the core to a change in the voltage on the core. The transient process tracks the signal of its task, which is formed by the setting unit 4 of the current intensity of the core.

The speed of the motor varies according to the expression

; 4-J4-- c), 5i,; - -:,

where is the initial (steady) speed value;

T; - constant start time

(g

 i

MH

, j - the moment of inertia, "C, MC - nominal

3

motor speed and torque); T - constant setpoint time 4 intensity. Since the change in the static load ij, during this transient process is not significant, the signal at the output of the speed controller 3 changes as a function

one

RS

one

  about 2tj b

..,

 Sl

- FROM ot-t

/.Ij 1, l

where the initial deviation of the speed reference signal from the set value

0 A voltage is formed at the output of the scale amplifier 14.

UA.y to. Udt /,

where K „is the transmission coefficient of the scale amplifier; - - derivative of speed, measured by differentiating element 16;

and - the voltage at the output of the amplifier-limiter 5, the relative value of this voltage is limited to +1).

The increment of the core current in this transient is determined by the enemy

i - / T-Jt; f-t.

- yi, and

Derivative speed of the engine is

 -t.

S Given the last two expressions

The voltage at the output of the scale amplifier 14 can be written as follows:

12

Thus, if you choose K 0.5, then when reducing the output signal of the controller 3 speed to. the value of U 0.55 speed deviation from the steady-state value is half from the initial 5 and the output voltage Up of the speed regulator 3 becomes equal to the voltage and m of the scale amplifier 14. At the same time, the sign of the signal at the input of the unit 4 of the core current intensity 4 changes cor current

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begins to decrease linearly (Fig. 2, curve 19). The deviation of the motor speed is about a predetermined value (Fig. 2, curve - 5 va 20) and the voltage at the output of the scale amplifier 14 (Fig. 2, curve 21). MOHOTOHHq decreases to zero.

If the moment of inertia of mechanism 10 changes, for example, it increases, then when the speed setting jumps, the engine speed increases more slowly and the speed error decreases more slowly (Fig. 2, line 22). The current cor 15 (Fig. 2, curve 23) increases linearly until the voltage of the scale amplifier 1 4 (Fig. 2, curve 24) becomes equal to the voltage of the speed controller 3. 20 Then the voltage of the amplifier - limiter 5 changes the sign and the speed control error monotonously rushes to zero.

Thus, regardless of the magnitude of the moment of inertia of the electric drive, transient processes in the system remain optimal in speed with a given limitation on the derivative of the current cor, defined by JQ constant time Tc of the unit 4 of the current intensity cor. If set with another value T, for example, smaller, then transients proceed faster, but their character remains optimal in speed. This is due to the fact that the switching surface of the amplifier-limiter 5 does not depend on the parameters T: and Tj, the drive system not included in the expression for the signals of the regulator 3 of the speed Up Kpj (-5-) and the scale amplifier 14 U, jj K ,.

If the step increment of the speed reference signal is high enough that the core current reaches the maximum possible value of L in the transient process, determined by the conditions of the electric motor switching - 0 bodies (Fig. 3, curve 25), the sensor 18 of the limiting mode produces a signal disconnecting control key 11. In this case, the voltage at the output of the integrator 12 with a reset is remembered. Since the current cor in the time interval tj ... t2 remains unchanged, then the derivative of the motor speed measured by the differential

0

51

the raiding link 16 is constant, and the error in speed (Fig. 3, curve 26) decreases linearly. Thus, the voltages at the output of multiplier 15 and scale amplifier 14 over time tj .-. T remain unchanged (Fig. 3, curve 27). As soon as the voltage of the speed regulator 3 becomes equal to the voltage of the scale amplifier 14 (Fig. 3, curves 26 and 27, time t), the current of the core begins to decrease, the speed deviation from the predetermined value monotonically rushes to zero.

In order to avoid accumulation of an integrator error, its voltage is zeroed at zero values of the derivative of the velocity, i.e. in the installation of (quasi-established) modes.

The invention allows, with a constant controller structure and a change in the system parameters (inertia moment, constant setting time of the current intensity core), transient processes that are optimal in response to the constraints imposed on the control coordinates, current cor and its derivative. In the electric drive under consideration, the control algorithm does not require knowledge of the parameters of the electric drive, in particular, the moment of inertia, i.e., the electric drive is invariant to change the parameters.

ten

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Claims (1)

Invention Formula A DC motor that contains a DC motor connected to a controlled converter, the control circuit of which includes serially connected speed controller, an intensity control unit, implemented as a series-connected limiting amplifier and integrator with a limiting unit in the reverse circuit. connections, and a current regulator, as well as speed and current sensors connected to the inputs of the corresponding 5 regulators, are distinguished by the fact that, in order to form optimal ystviyu transients when the parameters 2® of the electric drive, a sequentially connected control key, an integrator with a reset, and a module allocation unit, as well as a scale amplifier, and a multiplication unit,  the differentiating element, the null organ and the restriction mode sensor, the input of which is connected to the said restriction unit, and the output to the control input of the controllable key, the outputs 30 of the differentiating link and the module allocation unit are connected to the inputs of the multiplication unit, the output of which is connected to the intensity setting unit through a scale amplifier, The 35 reset to zero of the integrator with a reset through the null-organ is connected to the output of the differentiating link, and the input of the controlled key is connected to the output of the amplifier-limiter of the intensity setter. 23 Editor N. Rogulich Order 2144/56 Circulation 631 Subscription VNISCHI State Committee of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab. D. 4/5 Production and printing company, Uzhgorod, st. Design, And Compiled by V. Kuznetsova Tehred L.Oleynik Proofreader M. Sharoshi