SU1716065A2 - Drill electric drive - Google Patents

Abstract

The invention relates to an automated electric drive (E) and makes it possible to increase the reliability of its operation in inverter modes. To do this, E is provided with an inverter breakout protection unit 28 and a fifth key 34. When operating in motor mode, keys 10 and 14 are closed, and keys 12 and 15 are open, i.e. there is a signal at the first and third outputs of the switching unit 20. With a positive voltage at the output of intensity control 6, the signal from the output of the one-dimensional comparator 29 through the first element AND-NOT 31 does not reach the first input of the third element AND-NOT 33. The signal at the output of the second element AND-NOT 32 is present, therefore at the output of the AND element -NOT 33 signal is. Key 34 is closed and the formation of electromechanical harak

Description

The invention relates to an automated electric drive and can be used in the automation of technological processes, for example, in the construction of control systems for electric drives of geological exploration drilling machines.

The aim of the invention is to increase the reliability of the drive in inverter modes.

FIG. 1 shows a functional diagram of the proposed electric drive; FIGS. 2 and 3 show time diagrams of the operation of some units of the device; in fig. 4 - timing diagram of the operation of the inverter breakthrough protection unit.

The electric drive of the drilling machine includes a current transformer 1, the output of which is connected to a current sensor 2, the output of which is connected to a current cutoff unit 3, and the output of the setting device 4 of the rotation frequency is simultaneously connected to the input of the first nonlinear element 5 and to the input of the intensity setting 6 connected to the first input of the first adder 7, to the second input of which voltage sensor 8 is connected, and the output of the first adder 7 is connected to the input of voltage regulator 9, the first output of which through the first switch 10 is connected to the first input of the second adder 11, and the second output of the voltage regulator 9 through the second switch 12 is connected to the first input of the second adder 1.1, to the second input of which the output of the current cutoff unit 3 is connected, and the output of the second adder 11 through the first control unit 13 is connected the inputs of the third 14 and fourth 15 keys, the output of the third key 14 is connected to the control input of the first controlled rectifier 16, and the output of the fourth key 15 is connected to the control input of the second controlled rectifier 17. The first and second controlled rectifiers and turned on and counter inputs connected through a current transformer 1 to the power supply, and outputs through the sensor 18 current cor - to the core

motor 19. The output of the first adder 7 is connected to the first input of the switching unit 20, to the second input of which the output of the current-current sensor 18 is connected.

The first and second outputs of the switching unit 20 are connected respectively to the control inputs of the first 10 and second 12 keys, the third and fourth outputs of the switching unit 20 are connected to the control

inputs, respectively, of the third 1.4 and fourth 15 keys, and the output of the first nonlinear element 5 is connected to the first input of the second nonlinear element 21, to the second input of which the output is connected

current sensor 2. The output of the threshold voltage source Unop is connected to the third input of the second nonlinear element 21. The first switch output 22 modes of operation is connected to the second sensor input

2 current, the second and third outputs of the switch 22 operating modes are connected respectively to the fourth and fifth inputs of the second nonlinear element 21. The output of the first nonlinear element 5 is connected to the second input of the third adder 23, to the third input of which is connected the output of the source of the set value of the nominal field current DI EX ., and the output of the third adder 23 is connected to the input of the controller 24

excitation voltage, the output of which through the second control unit 25 is connected to the third controlled rectifier 26, the output of which is connected to the motor excitation winding 27. The device contains

also block 28 protection against breakthrough inverter, which includes a unipolar comparator 29, the input of which is connected to the output of the intensity setting device 6, and the output is connected to the element NO 30 and the first input. The first element AND-NOT 31, the second input of which is connected to the third output of the switching unit 20, the fourth output of which is connected to the second input-the second element AND-NOT 32, the first input of which is connected to the output of the HE element 30, Outputs of the first 31 and second 32 elements AND NOT

connected respectively to the first and second inputs of the third element I-HE 33, the output of which is connected to the control input of the fifth key 34, the input of which is connected to the output of the second nonlinear element 21x, and its output connected to the first input of the third adder 23.

Current sensor 2 is designed to rectify the output signal of current transformer 1. The contact of the manual switch 22 of the electric drive operating modes is introduced into the current sensor 2, which is intended to change the transmission coefficient of the current sensor 2, FIG. 2, and the static characteristics of the current sensor 2 are shown. In the long-term operation of the electric drive (), the contact of the manual override 22 operating modes is open, i.e. U22-1 is 0, and current sensor 2 has a high transmission coefficient. In the intermittent operation mode of the electric drive (100%), the switch contact of the 22 operating modes of the electric drive is closed; U22-1 1, and current sensor 2 has a lower transmission coefficient (Fig. 2, a) ..

The overcurrent block 3 is a threshold element. When the output signal of sensor 2 reaches the value of the threshold of block 3 (which can be set, for example, by means of a stabilizer), a signal appears at the output of block 3, which is fed to the second adder 11. Since block 3, the current cutoff has a large gain factor With a further increase in the signal from current sensor 2, the output signal of unit 3 rapidly increases, which leads to the compensation of the output signal of voltage regulator 9. FIG. 2.6 shows the static characteristic of the block 3 current cutoff.

The first nonlinear element 5 with the dead band and saturation is designed to extract from the output signal of the setpoint device 4 the rotational speed of the positive setpoint signal Us to the change of the excitation current. In Fig., 3, a, its static characteristic is presented, where (-A, + A) is the insensitivity zone. :

The accelerator and deceleration rate setter 6 is an integrator with adjustable intensity of rise and fall of the signal. The steady state output of the setpoint 6 is always equal to the input level.

Control units 13 are vertically controlled nodes. The inputs for blocks 13 and 25 are the analog outputs of the adder 11 and voltage regulator 24, respectively.

At the outputs of blocks 13 and 25, control pulses are generated, intended for opening thyristors in controlled rectifiers 16, 17 and 26, respectively. Here, the amplitude and width of the control pulses generated at the outputs of the blocks 13 and 25 are unchanged parameters, and their phase is determined by the amplitude of the input signal. When the output signal of the blocks 11 and 14 changes, the phase of the control pulses at the output of the blocks 13 and 25 changes, which leads to a change in the moment of switching on the thyristors in the controlled amplifiers 16, 17 and 26. As a result, the voltage at the core windings changes 19 and excitation windings 27.

Switching unit 20 is designed to control the keys 10, 12, 14, and 15. Switching the unit is carried out as a function of the polarity of the output signal of the first adder 7 if there is no current in the engine circuit 19 (the inhibit signal from the zero current sensor 18). If the polarity of the output of the first adder 7 is positive, output signals appear on the first and third outputs of the switching unit 20, and the keys 10 and 14 are closed. On the second and fourth outputs there are no signals, and the keys 12 and 15 are open. When the polarity of the output signal of the first adder changes from positive to negative, block 20 should switch, but it will not switch until the current in the crust circuit of the executive motor 19 becomes zero. At this point in time, the inhibit signal from the output of current current sensor 18 becomes zero, and block 20 is switched. The signals at the first and third outputs become equal to zero, and the keys 10 and 14 open. On the other hand, signals appear on the second and fourth outputs of block 20, and keys 12 and 15 are closed.

The second non-linear element 21 with the dead band by saturation and variable gain is designed to correct the reference signal for a change in the excitation current as a function of this signal and the output signal of the current sensor 2. Three signals are input to the input of the element 21: the threshold Unop., The output signal of the block of the first measuring element 5 and the signal from the current sensor 2. In addition, the composition of the second nonlinear element 21 introduced two contacts of the manual switch 22 modes. In the long-time operation of the electric drive (), the contacts of the switch 22 of the operation modes are open, and the second nonlinear element 21 has a large gain factor.

Therefore, when the signal from sensor 2 exceeds the threshold signal Unop. At the output of element 21, an output signal appears that goes to the third adder 23. In continuous operation, the output signal of block 5 does not affect the operation of the second nonlinear element 21, since due to the open contact of switch 22 of operating modes the signal of block 5 the input element 21 is not received.

In the intermittent operation mode of the electric drive (100%), the contacts of the manual switch of the 22 operating modes are closed. The second non-linear element 21 has a small gain factor, and through a closed contact, the output signal of the first non-linear element 5 arrives at its input. In FIG. 3.6 shows the static characteristics of the second nonlinear element 21 for long (dashed line) and intermittent (continuous lines) modes of operation.

The drive works as follows.

When moving the control knob of the setting knob 4 of the engine rotation frequency, a reference signal is generated at its output, which simultaneously arrives at the inputs of the setting knob b of the intensity of the first nonlinear element 5 with the dead zone.

At the output of the first nonlinear element 5, the signal is equal to zero until the signal from the output of the setting device 4 of the engine rotation frequency exceeds the deadband (-A, + A, Fig. 3, a) of element 5.

The voltage at the output of the intensity master B varies from zero to a certain steady-state value. The dead zone of the element 5 is chosen equal to the amplitude of the output signal of the setting device 4 of the engine rotation frequency, at which the nominal voltage on the engine bark 19.

With further movement of the control knob by the setting device 4 of the engine rotation frequency, the amplitude of the output signal from the output of the intensity setting device 6 remains unchanged, and the output signal of the first nonlinear element 5 begins to increase from zero to a certain value, the value of which is determined by the angle of rotation of the control knob by setting device 4 engine speed.

Until the executive motor 19 accelerates to the rated speed, the output of element 5 is zero. Therefore, the input signal of the regulator 24 of the excitation voltage is determined by the setting signal of the nominal

excitation current DI int., supplied to the third adder 23 together with the signals of elements 5 and 21, which are equal to zero. In this case, a rated current flows through the excitation winding 27.

0 The intensity setting device 6 forms a linearly varying voltage, the intensity of which change determines the acceleration (deceleration) rate of the engine 19. The voltage regulator 9 together with

5, the voltage sensor 8 and the first adder 7 form a voltage stabilization circuit on the engine bark 19 at a level determined by the output signal of the intensity control b. Under the influence of the output signal of the intensity setting device 6 and the voltage sensor 8, a signal proportional to their difference appears at the output of the adder 7. As a result, the direct and inverse outputs of the voltage regulator 9

5, signals are also generated.

Keys 10 and 12 cannot be simultaneously closed, i.e. when one of them is closed, the other is necessarily open; Keys 14 work in the same way.

0 and 15.,

Since at the first moment of time the voltage on the engine bark 19 is zero, the signal from the voltage sensor 8 is also zero, the entire signal from the output of the setpoint b intensity is fed to the input of the voltage regulator 9. The power current in the core circuit is missing, so the signal to prohibit the switching of the switching unit 20 from the sensor 18 is absent. Under the action of the differential signal from the output of the first adder 7, block 20 includes either keys 10 and 14, or keys 12 and 15.

Depending on which key is closed, to the input of the first control unit 13

5, the signal comes from the direct or inverse outputs of the voltage regulator 9 after the second adder 11, since at the second input of the second adder 11 the signal from the output of the current cutoff unit 3 is zero. Block 13

Control 0 generates control pulses for rectifiers.

16 or 17 and their phase shift is proportional to the input signal from the output of voltage regulator 9.

five

Via keys 14 or 15 control pulses, the rectifier actuators 16 or

17 and at the output of one of them, the supply voltage of the engine winding 19 is generated.

At the output of the voltage sensor 8, a voltage is applied to the VITS, which is fed to the adder 7. However, since an increasing signal is generated at the output of the intensity setting device 6, its amplitude will be greater than the amplitude of the signal from the voltage sensor 8. Therefore, the polarity of the difference signal at the output of the adder 7 does not change. Consequently, block 20 will retain its state, and keys 10, 12, 14, and 15 will remain as they were, i.e. motor 19 will continue to accelerate in the same direction.

In the steady state, there is always a difference between the reference and feedback signals, under the influence of which the engine speed setpoint set by the position of the setting knob 4 will be maintained.

In the event that the acceleration intensity of the executive motor 19 is determined by the intensity indicator 6 sufficiently high, then the current of the motor core 19 will reach such a value that the output voltage of the current sensor 2 may reach the insensitivity threshold of the current shut-off unit 3. At the output of unit 3, according to Vits, the voltage that will be subtracted from the voltage of the voltage regulator 9 in the second adder 11. The control voltage of the unit 13 due to this decreases and will be maintained at such a level that the current of the motor 19 does not exceed the set values depending on the mode of operation of the drive. Engine acceleration rate

19 in this case, it will become lower than the intensity set by the setting unit 6 and will be determined only by the load on the motor shaft 19. In this case, the engine will be accelerated according to the limiting electromechanical characteristic having the form of an excavator.

In case the rotational speed control handle 4 sets the opposite polarity of the reference signal, the drive operation algorithm is similar to the above with the difference that the polarity of the difference signal at the output of the adder 7 will be opposite, block.

The switch 20 switches on the other keys, the control unit 13 will be connected to another output of the voltage regulator 9, the pulses from the output of the block 13 will flow to the other rectifier 16 or 17, the voltage on the main winding of the engine 19 will be different polarity.;. .; .. As mentioned above, in motor mode, the key 34 is always closed.

Let us now assume that after the end of acceleration of the engine 19 to the nominal rotational speed, there is no torque on the motor shaft, and the control knob of the setpoint 4 is set in such a way that a reference signal is also generated at the output of the first nonlinear element 5. Moreover, since the reference signal at the output of the intensity setting device 6 does not change, the voltage on the engine bark 19 is also unchanged.

The reference signal from the output of the first nonlinear element 5 is fed to the third adder 23. At the output of the third adder 23, a signal is formed and fed to the input of the regulator 24 of the excitation voltage.

Under the action of this signal, the controller 24 changes (decreases) its output signal, the control unit 25 changes the phase of the control pulses fed to the controlled rectifier 26. As a result

This changes (decreases) the voltage at the output of the rectifier 26, therefore, the excitation current.

The engine 19 begins to accelerate to a rotational speed determined by the flow.

excitation, and therefore, the signal setpoint 4, i.e. The frequency of rotation of the engine 19 in the second control zone is determined by the position of the control knob of the setting frequency regulator 4.

If the moment of resistance on the motor shaft increases, then under its influence the current in the core winding of the engine 19 begins to increase, and consequently, the signal from the transformer 1 increases.

current.

The second non-linear element 21c zone

insensitivity, saturation and variable gain is designed to change the current, setpoint

the electric drive in the second control zone when and when the power constant mode is applied at. Functionally, the element 21 performs a change in the control signal of the regulator 24 of the excitation voltage so that the excitation current increases in proportion to the current exceeding the nominal value of the core.

The change in the type of characteristics realized by the electric drive is carried out by a manual switch 22 of operating modes, which performs the switching of both the element 21 and the current sensor 2.

The 100% on-off voltage of the electromechanical characteristic of the electric drive is determined by the transfer coefficient of the nonlinear element 21 at the second input LJ2, and the threshold is determined by the voltages of the source Unop. As well as the voltage at the output of the first nonlinear element Us.

In the mode, when the current of the actuator motor 19 reaches its nominal value at the output of the element 21, a voltage of 1) 21 appears, which due to the high transmission coefficient of the element 21 becomes large with the slightest increase in the current of the core. In this case, the resulting signal at the output of the adder 23 (the fifth key 34 is open only in the inverter mode of operation of the controlled rectifiers 16 and 17) changes in such a way that the excitation current increases, the rotation frequency of the motor 19 decreases, and the torque developed by the electric drive increases by increasing the excitation flow of the engine 19. As a result, the electric drive will develop an increased torque on the shaft by increasing the excitation flow of the engine 19 while reducing the rotational speed with little or no increase in the core current.

As a result, the element 21 provides for stabilization of the current of the core at the nominal level by increasing the excitation flow as a function of the current exceeding the core of the nominal value. This ensures that the engine 19c is rated at its rated output.

In the mode, the second nonlinear element 21 has a significantly lower transmission coefficient for the input U2, therefore, the electromechanical characteristic has a flatter form. In this mode of operation of the drive to the input of the element 21 except for the voltage source Unop. also a signal Us is received, which is necessary to change the resultant trigger threshold of element 21.

In this case, the resulting trigger threshold of the second nonlinear element 21 is a function of the output signal of the first nonlinear element 5, which in the second control zone is proportional to the frequency of rotation of the engine 19, due to which the electromechanical characteristic is maximum allowable for the actuator at 100% DC.

In accordance with the foregoing, element 21 is used to form a section of the characteristic of the electric drive, both when the voltage of the task to weaken the field current and the load on the motor shaft changes.

FIG. 4 shows time diagrams of an inverter breakout protection unit 28.

4 Suppose that the electric drive operates in the steady state, i.e. At the output of the intensity setting device 6, a positive voltage is present in FIG. 4, a). At the output 1 of the voltage regulator 9, a signal is generated, which is fed to the input of the second adder 11, the output of which also contains a signal. The control unit 13 forms and shifts the control angles in proportion to this signal. Since there is a voltage at the output of one of the controlled rectifiers, voltage sensor 8 generates a signal that enters the input of the first adder 7. The output from the adder 7 arrives at the input of the switching unit 20. Since the electric drive

5 is in a static state, the signal from the output of intensity controller 6 is greater than the feedback signal from voltage sensor 8, i.e. their difference is positive, therefore, on the first and third outputs of block 20

0 switching signal is formed Log. 1 (keys 10 and 14 are closed), and on the second and fourth outputs of the switching unit - Log. O (keys 12 and 15 are open).

At time ti (Fig. 4, a) the signal

5 at the output of the setter 6 intensity begins to fall linearly. The signals at the outputs of blocks 9, 11 and 13 are also reduced, the difference signal at the output of adder 7 changes sign, due to which block 20 switches. At its first and third outputs, the signals Log are formed. О (keys 10 and 14 are opened), and on the second 20.2 and fourth 20.4 outputs the Log signals are formed. 1 (keys 12 and 15

5 are closed). Switching keys 10,12 and 14, 15. The electric motor 19 enters the generator mode (II quadrant), i.e. regenerative braking of the electric drive takes place.

0 At the moment of time r, the signal at the output of the intensity setting device 6 will become zero, the electric motor will stop. If the signal at the output of the setting device 6 continues to vary linearly (it will increase

5 amplitude negative voltage),. the motor 19 will accelerate to a rotational speed corresponding to the signal level at the output of the setter 6. At the same time, the voltage is not; output setpoint 6 has

0 negative sign, on the first and third

the outputs of block 20 switching - Log; one

(keys 10 and 14 are open), and on the second and

 fourth exit - Log. 1 (keys 12 and 15

closed).

5 At the time ti (Fig. 4, and) the signal at the output of the setting device 6 begins to increase linearly, and the electric motor goes into generator mode (IV quadrant). The operation algorithm of the electric drive is similar to the above, i.e. switches 12, 10, and 15, 14 are switched, and the drive performs regenerative braking. It is obvious that in the I quadrant the signal at the output of the intensity sensor 6 is positive, and at the third 20.3 output of the switching unit 20 - the signal Log. 1 (key 14 is closed). When moving the motor

19c generator operating mode (II quadrant), with a positive signal at the output of setpoint 6, the third 20.3 output will be Log. O (key 14 is open), and on the fourth 20.4 exit - Log. 1 (key .15 closed).

In the third quadrant, the signal at the output of the setting device 6 will be a negative sign, at the third 20.3 output - the Log. O (key 14 is open), and on the fourth 20.4 exit - Log. 1 (key 15 is closed). In the transition of the electric motor 19 in the generator mode of operation (IV quadrant) with a negative signal at the output of the setting device 6 at the third 20.3 output - Log. 1 (key 14 is closed), and on the fourth 20.4 output - Log. O (key 15 is open). Thus, the algorithm of the drive allows the following one-to-one correspondences to be established.

Motor operation mode of the electric drive:

1) De is positive and the key 14 is closed (and 20 .. 1);.-...,

2) 11b is negative and key 15 is closed (1120 .. 1).

Generator mode of the electric drive (inverter mode of operation of controlled rectifiers):

1) Ue is positive and key 15 is closed (i2o .. D);

2) Ue is negative and key 14 is closed (.. 1).

Based on these correspondences, an inverter breakthrough protection unit 28 is constructed.

Consider the work of this unit.

In the time interval preceding ti (Fig. 4, a), the electric drive operates in motor mode. Positive voltage is output from Vas 6, so the output of the unipolar comparator 29 is level equal to Log. 1 (Fig. 4,6), at the output of the element NOT 30 - Log. 1 (Fig. 4, c). At the third 20.3 block output

20 switches - Log. 1 (Fig. 4, d), and on the fourth 20.4 - Log. O (Fig. 4, d). Thus, at the inputs of the first element AND-EUT 31 there are two signals of the Log. 1 and, therefore, at its output, the signal Log. O (Fig. 4, e). At the inputs of the second element AND-NOT 32 two signals Log. Oh and, therefore, at its output - Log. 1 (Fig. 4, g). Thus, at the inputs of the third element AND-NOT 33, the combination of signals from Log. 1 and Log. Oh, and at his exit - Log. 1 (Fig. 4, h).

As long as the drive works in motor mode, fifth key 34

closed (Fig. 4, h), and the formation of electromechanical characteristics is carried out using the second nonlinear element 21. At time c, the electric drive switches to regenerative braking, while the output of the comparator 29 retains its state (Fig. 4, a), since the output signal of the setting device 6 positive sign. The element EE 30 also maintains its state Log. ABOUT.

At this moment in time, at the third 20.3 output of the switching unit 20, the signal Log. Oh, and on the fourth 20.4 - Log. one,

those. at time ti at the inputs of the first

element EHNE 31 combination of the log. Oh and Log. 1, the ion changes its state to Log. 1. The second element IS-HE 32 does not change its output state, since at its inputs there is a combination of Log. 1 and Log. A. As a result, at the moment of time ti, the third AND-HE element 33 changes its state to Log. O. Fifth key 34 opens (Fig. 4, g).

At time t2, the signal at the output of the setpoint intensity 6 will be equal to

to zero. In the event that the signal at the output of the setting device 6 continues to linearly increase in amplitude of the negative sign, the elements 29 and 30 change their output state. On the third 20.3 and fourth 20.4 outputs

block 20, the signals retain their previous state, the drive begins to accelerate in the opposite direction.

Therefore, on the time interval

 (Fig. 4, a) the regenerative braking of the electric drive is accompanied by the opening of the sixth switch 34, which eliminates the possibility of the appearance of positive feedback on the EMF

engine

If the drive operates with a negative voltage at the output of the setpoint 6 (Fig. 4, i), the algorithm of operation of the inverter breakthrough protection unit 28 is similar to the above. FIG. 4, and-4, p shows the time diagrams of the operation of the elements of the block 28 for this case.

Thus, the introduction of an inverter breakthrough protection unit 28 makes it possible to eliminate the influence of the second nonlinear element 21 on the operation of an electric drive in an inverter mode of controlled rectifiers, i.e. the possibility of positive feedback on the EMF of the engine during its regenerative braking is eliminated. This allows you to limit the growth of the motor's EMF within the allowable (under protection conditions against inverter breakthrough) limits.

Since the possibility of an unlimited increase in the EMF of the motor in the inverter mode is significantly reduced, the possibility of emergency situations is reduced, and consequently, the reliability of operation of the electric drive as a whole increases.

Claims (1)

The invention of the electric drilling machine for aut. St. No. 1641969, characterized in that, in order to increase the reliability of the electric drive in inverter modes, the electric drive is equipped with a fifth key and an inverter breakout protection unit, while the output of the second nonlinear element is connected to the first input of the third sum- tor by the fifth key, and protection block Inverter breakthrough contains a unipolar comparator, an NOT element and three NAND elements, while the output of a unipolar comparator is connected to the first input of the first and NOT element to the first input of the second NAND element, and the outputs of the first and second AND NAND element connected to the corresponding inputs of the third element IS-NOT, the input of the unipolar comparator is the first input of the block, the second inputs of the first and second elements of the IS-NOT are respectively the second and third inputs of the block, and the output of the third element IS-NOT is the output of the protection block breakthrough from the inverter, the output ramp-function generator, and outputs third and fourth switching unit connected respectively to the first, second and third inputs of the relay by breaking the inverter, whose output is connected to the control input of the fifth key, 6 FIG. 2 C Fig.Z  - “f / ner