SU1582314A1 - Electric drive with limitted forces in excavator mechanisms - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drives for lifting and heading excavators. The aim of the invention is to increase reliability. The device contains series-connected voltage source 1, speed regulator 2, core current regulator 3 and reversible thyristor converter 4, the output of which is connected to the motor core 5. Sensors 6 and 7 of the speed and core current are connected to the inputs of the corresponding regulator tori connected in series the first diode 8, the acceleration sensor 9, the second diode 10 and the nonlinear element 11 with the dead zone, the output of which is connected to the input of the regulator 2 rotational speed. The use in this device of the unit 20 for maintaining the stability of the safety margin of the ropes allows ensuring the stability of the safety margin of the ropes and thereby increasing the reliability. 1 il.

Description

four

The invention relates to electrical engineering and can be used in electric drives for lifting and heading of Excavators,

The aim of the invention is to increase reliability,

The drawing shows a diagram of the drive.

The electric drive contains successively connected source1 of the driving voltage, regulator 2 rotational speed, regulator 3 of the current box and reversible thyristor device, the output 49 of which is connected to the motor pole 5, the speed sensor 6 and the current box 7, connected with inputs of regulators 2 and 3, respectively, of rotational speed And current, connected to the output of sensor 6 of rotational speed, serially connected first diode 8, sensor | acceleration, second diode 10 and non-linear) 1Y element 11 with dead band, the output of which is connected to the input of speed controller 2.

The electric drive also contains an analog storage unit 12, a zero-body 13, a first adder 14, pulse shapers 15 and 16, a functional converter 17 and a second adder 18. The limiter 19 block in the feedback circuit of the speed controller 2 is controlled The information input of the analog storage unit 12 and the input of the zero-body 13 are connected to the input of the acceleration sensor 9, the control input of the analog storage unit 12 is connected to the output of the first adder 14, whose inputs are connected to the outputs of the first 15 and second 16 pulse shapers, the pulse shaper input 15 is connected to the output of the nonlinear element 11 with an insensitive zone; the pulse shaper 16 input is connected to the zero-body output of $ 13, and the output of the analog storage device 12 is connected via a functional converter to the first input of the second adder 18, the second input of which is connected to a constant voltage source U, and the output of the adder 18 is connected to a control limiter 19 in the feedback circuit of the controller 2 of the rotation frequency.

The combination of blocks 12-19 forms a block 20 for maintaining the stability of the rope safety factor.

The drive works as follows

In normal operation, i.e. in the absence of a locking device, the device functions as usual a dual-circuit slave control system with an internal core current control loop and an external speed control loop.

Diodes 8 and 10 ensure the appearance of a signal at the input of the nonlinear element 11 only when the engine is slowed down in the digging mode, or when the bucket is raised (extension of the handle). When the bucket is lowered (the arm is steeped), the diode 8 is locked; when the diode 8 is open and the engine is accelerated, the diode 10 is locked.

The nonlinear element 11 is adjusted so that the signal from the output of the acceleration sensor 9 at the maximum possible deceleration values that occur during normal operation (i.e., without stopping) is less than the dead zone of the nonlinear element 11. The voltage at the output of the analog storage device 12 and at the output of the functional converter 17 are equal to zero, therefore the voltage limit of the block 19 of the regulator 2 of the rotational speed depends only on the voltage U1 supplied to the second I / O of the adder 18, and the corresponding t on specification static retaining force of the motor.

In the storage mode, the signal at the output of the acceleration sensor 9 becomes larger than the dead band of the nonlinear element 11,

As a result, a negative polarity voltage appears at the output of the nonlinear element 11, which is fed to the input of the rotational frequency controller 2 and exceeds the positive polarity of the input voltage of the regulator 2 from the source 1 of the driving voltage.

The resulting reference signal at the input of the speed controller 2 becomes significantly negative, the maximum voltage appearing at its output specifying a negative value of the current cor. Under the action of e, the voltage of the current, the core changes

515873

the direction and the regenerative braking of the electric motor begins. In regenerative braking mode, part of the kinetic energy stored in the electric drive before the start of the stopping process 5 is converted into electrical energy and returned (recovered) to the network, which

provides a reduction in dynamic

force in the elastic connection when stopping Since in the regenerative braking mode when the locking controller 2 speed control operates in the limiting mode, the motor force reference in this mode is proportional to the magnitude of the limiting voltage of the rotation frequency regulator 2, which is controlled by the limiting unit J9 feedback loop of this controller.

The voltage from the output of the nonlinear element 11 is fed to the input of the pulse driver 15, and a voltage pulse appears at the output of the driver 15, which is fed through the adder 14 to the control input of the analog storage unit 12. When this pulse arrives, it is recorded and stored in the block 12 voltage supplied to the information input of this device from the rotational speed sensor 6. Thus, after the arrival of a pulse from the generator 15, a constant voltage appears at the output of the analog storage unit 12, which is proportional to the initial speed of the engine in the locking mode Vfo.

This voltage is fed to the input of the functional converter 17, the output voltage of which is fed to the adder 18. The voltage from the output of the adder 18 is equal to the voltage of the limiting unit 19, i.e. it sets the value of the engine effort in regenerative braking mode,

The characteristic of the functional converter 17 provides for the change of the engine forces F dr as a function of the initial reduced speed of the engine V. (.

This law corresponds to the unchanged maximum dynamic force in the elastic coupling of the mechanism to the maize, regardless of the magnitude of the initial reduced engine speed.

V

By keeping the given

P values are provided by constant

five

0

, 0

50

five

146

in the safety margin of the ropes and the working equipment of the excavator during locking, which increases reliability.

Throughout the entire locking mode, the value of the motor forces in the regenerative braking mode is maintained, since the voltage at the output of the analog storage unit 12 remains constant.

At the end of the locking process, when the engine speed drops to zero, a voltage appears at the output of the null organ 13, which enters the input of the pulse driver 16, and a voltage pulse occurs at the output of the driver 16.

This pulse is transmitted through the adder 14 to the control input of the analog storage unit 12. At the time the pulse arrives from the shaper 16, block 12 records and stores the voltage supplied to its information input from the rotational speed sensor 6, which is zero at this time instant . Therefore, at the outputs of the device 12 and the converter 17, the voltage also becomes zero, the output voltage of the adder 18 is set to the initial voltage, which depends only on the voltage U at its input and is equal to the limiting voltage of the block 19 of the regulator 2 corresponding to the static stop reference an effort

engine f

st

The characteristic of the functional converter 17 is determined by the ratio

 AR

FCT G

t I

UTR shs

F k

 At

ri7 -o).

de K. - the specified value of the coefficient of dynamism of the force in the elastic bond during stopping;

V - initial reduced to livestock

engine rush mode

stopper;

FUT static stop force;

m is the reduced mass of the rotating parts of the electric drive;

c is the equivalent stiffness of the elastic bond;

F. - engine power mode

R

recuperative braking when snoring.

The relation given above with reference to the functional converter 17 can be written as follows:

U2 AU, - B,

where U and U., are the output and input signals of the functional converter, respectively;

A and B constants. The device automatically changes the engine force in the regenerative braking mode 13 of the initial speed function of the engine when it is unlocked, and this change is carried out according to the law ensuring the constant dynamic force in the elastic

Intermittent locking regardless of the initial speed of the engine, i.e. regardless of the initial kinetic energy of the drive,

Due to this, the safety margin of the ropes AND working equipment is maintained, which increases the reliability of the excavator mechanisms,

Claims (1)

Invention Formula An electric drive with limited dynamic forces in excavator mechanisms, containing serially connected source of driving voltage eg Xeni, rotational speed controller with feedback limiting unit, current regulator core and reversible thyristor converter, the output of which is connected to the motor kor, sensors rotational speed and current core, connected to the inputs of the corresponding regulators, as well as connected to the frequency sensor ,, 0 five 0 d five rotationally connected diode, acceleration sensor, second diode and nonlinear element with dead band, the output of which is connected to the input of the speed regulator, characterized in that, in order to increase reliability, it is additionally equipped with a rope durability unit containing analog a storage unit, a null organ, whose information input is connected to the acceleration sensor inputs and an analog storage unit, the first adder, two pulse generators, a functional the transducer and the second adder, and the limiting unit in the feedback circuit of the rotational speed controller is controlled, the control input of the analog storage unit is connected to the output of the first adder, the inputs of which are connected to the outputs of the first and second pulse formers, the input of the first pulse generator is connected to the output of the nonlinear element with the dead zone, the input of the second pulse shaper is connected to the output of the null organ, the output of the analog storage unit is connected via the function An initial converter to the first input of the second adder, the second input of which is connected to a constant voltage source, the output of the second adder is connected to a controlled limiting unit in the feedback circuit of the speed regulator, and the functional converter realizes the function U4 AU ,, В, where Ut and U 1 - respectively, the signals at the output and input of the functional converter j A and B are constants.