SU1436255A1 - D.c. electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be applied in dual-zone speed control circuits. The aim of the invention is to increase the speed and reliability of the electric drive. The electric drive contains a rhythm determination unit 17, the inputs of which are connected to the core current sensor 10, the module allocation unit 15 and the voltage sensor 12. The output of block 17 is connected to the excitation current controller 5. One of the inputs of the excitation current controller 5 through the non-linearity unit 14 is connected to the excitation winding temperature detection unit 16. When the temperature approaches an unacceptable level, a signal appears at the output of block 14, due to which the excitation reference decreases. Temperature control provides in the early electric drive the improvement of the conditions of the electric motor's mutation. 3 hp f-ly, 7 ill.

Description

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The invention relates to electrical engineering and can be applied in systems of two-zone speed control of electric motors of direct current of various mechanisms with a large moment of inertia on the shaft of an electric motor and operating with a large range of frequency control by varying the excitation current.

The purpose of the invention is to increase the speed and reliability of the electric drive.

In Fig, 1 shows a functional diagram of the drive; in fig. 2 - Skeme logical device; in fig. 3 is a diagram of the excitation current regulator for the exciter based on a magnetic amplifier and transistors of power switches; in fig. 4 shows a drive current regulator circuit for a thyristor exciter; in fig. 5 is a block diagram of the determination of the temperature of the field winding; in fig. 6 and 7 - characteristics of nonlinearity blocks.

The electric drive (Fig. 1) contains an electric motor, the main winding 1 of which is connected to the adjustable converter 2, and the excitation winding 3 to the control driver 4, the control circuit of which includes the excitation current regulator 5, the first and second inputs of which are connected respectively with the outputs of the dial 6 of the minimum excitation current and the first block 7 of the nonlinearity type saturation through the decoupling diodes 8 and 9, the sensors 10 and 11 of the core current and the excitation current and the sensors 12 and 13 of the voltage on the core and on the excitation winding, the second block ca. 14 non-linearities such as dead band and block 15 in the module slot.

The drive also contains a block

16 determine the temperature of the excitation winding and the mode detection unit 17 in the form of a logic device, and the electric motor is provided with an additional excitation winding 18 located at the main poles. In this case, the first, second and third inputs of the block 17 are connected respectively to the outputs of the current sensor 10 of the core of the voltage 12 on the core and on the block 15 of the allocation module connected by its output to the input of the nonlinearity block 7, and the output of the block

17connected to the third input of the excitation current controller 5, the fourth

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and the fifth inputs of which are connected respectively with the output of the excitation current sensor 11 and the outputs of the additional excitation winding 18, which together with the output of the voltage sensor 13 on the excitation winding are also connected to the inputs of the excitation winding temperature detection unit 16, the output of which is connected through the nonlinearity 14 to the sixth input of the excitation current controller 5.

Block 17 (Fig. 2) contains a non-inverting proportional amplifier 19, comparators 20 and 21, diodes 22-24, zener diode 25 and a logic element EXCLUSIVE OR 26, while the cathode of the Zener diode 25 serves as the second input of the logic device, the anodes of diodes 23 and 24 form the first and its third inputs, and their cathodes are connected to the inputs of a logical element of the EXTRACTOR OR 26, the output of which is connected to the cathode of the diode 22, is connected through the indicated diode to the limiting input of the non-inverting proportional amplifier 19, the input of which is connected to the anode stable 25, and the output is the output of the logic device.

Field current regulator 5 (Fig. 3) contains a capacitor 27 and a serially proportional amplifier 28 and a comparator 29, the output of which is an output, and the inputs are the fifth and sixth inputs of the field current regulator, the first and second noninverting inputs of the proportional amplifier 28 are the first and second inputs of the regulator, the first and second inverting inputs of this amplifier are the third and fourth inputs of the controller, while the capacitor 26 is connected between the output and the inverting input of proportional amplification l 19.

The field drive regulator 5 (FIG. 4) contains a capacitor 30, a resistor 31 and series-connected proportional amplifiers 32 and 33, the first and second non-inverting inputs of the first proportional amplifier 32 are the first and second inputs of the controller, and the first and second inverting inputs are third and the fourth inputs of the controller, the first and second inverting inputs of the second proportional amplifier 3 are respectively the fifth and sixth inputs of the controller, and the output of this amplifier is the output of the controller, while the condensation The torus 30 is connected between the invertirucic input and the output of the first proportional amplifier 32, between the non-inverting input of which and the output of the proportional amplifier 33 a resistor 31 is turned on.

The excitation winding temperature detection unit 16 (FIG. 5) contains a proportional amplifier 34 and a capacitor 35, the first and second inverting inputs of the proportional amplifier 34 are the first and second inputs of the block, respectively, the non-inverted input is the third input of the block, and the output is the output of the block 5 for determining the temperature of the excitation winding, wherein the capacitor 35 is connected between the inverting input and the output of the proportional amplifier 34,

The DC motor (Fig. 1) operates as follows.

When the motor is stationary, there is no current in the crustal circuit and the signals at the outputs of the sensors 10 and 12 of the current and voltage on the crust are zero. Therefore, there are no signals at the output of the module allocation module 15, the logical-kofo device 17, the non-linearity block 7 and the diode 8. When the excitation winding 3 is cold, the signals at the outputs of the temperature detection unit 16 and. block 14 nonlinearity also absent. As a result, the signal at the output of the excitation current regulator 5 is determined by the ratio of the reference signal supplied to its first input from

When a voltage appears at the output of the adjustable converter 2, signals appear at the outputs of the current and voltage sensors 10 and 12 on the core and the module 15 for extracting the module. These signals are fed to the inputs of the logic device 17.

Logical device (block 17)

works as follows.

In the motor mode of the motor, the voltage and current signals have a positive polarity. These signals come through

diodes 23 and 24 to the inputs of the comparators 20 and 21, the outputs of which form signals corresponding to logical units and arriving at the inputs of the EXCLUSIVE OR 26 element.

As a result, the signal at the output of this element is practically zero, and the signal at the output of the proportional amplifier 19 is also zero. In braking mode, the polarity of the signals

voltage and current is different. Therefore, at the cathode of one of the diodes 23 or 24, the signal will be absent, as a result of which one of the signals at the comparators outputs will be absent

20 or 21. As a result, at the output of the logical element EXCLUSIVE OR 26, a signal of a logical unit appears.

35

The signal from the logic element 26 through the diode 22 enters the limiting input of amplifier 19, and the magnitude of this signal is chosen so that it 40 practically does not limit the signal at the output of the proportional amplifier 19. The signal at the output of amplifier 19 depends only on the signal coming on his non-inverting

setter6 minimum current exciter-dd input. This input signal appears

neither through the diode 9, or the feedback signals from the outputs of the additional excitation winding 18 and the excitation current sensor 11, respectively, fed to the fifth and sixth inputs of the regulator 5 of the excitation current. The signal from the output of the excitation current regulator 5 is fed to the input of the exciter 4 and determines the current flowing

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only when the current reaches the permissible value, since the breakdown voltage of the Zener diode 25 is selected from the condition that the current reaches the maximum permissible value. Thus, at the output of the amplifier 19, the signal appears only in the braking mode when the current reaches the maximum permissible value,

in the excitation winding 3, and the voltage modes, this signal is absent, at the output of the sensor 13, the voltage voltage - The signal from the output of the amplifier 19 is equal to

and

There is no power supply to the output of the adjustable converter 2.

as well as from the output of the logic device 17, it is fed to the third input of the controller 5 of the excitation current.

only when the current reaches the permissible value, since the breakdown voltage of the Zener diode 25 is selected from the condition that the current reaches the maximum permissible value. Thus, at the output of the amplifier 19, the signal appears only in the braking mode when the current reaches the maximum permissible value,

and

as well as from the output of the logic device 17, it is fed to the third input of the controller 5 of the excitation current.

At the same time, a signal from the output of the module allocation module 15 is fed to the first input of the excitation current controller 5 through the nonlinearity block 7. Block 7 nonlinearity serves to limit the signal at the top level.

The excitation current regulator 5 for the exciter on the basis of a magnetic amplifier and power transistor switches (Fig. 3) works in the following way.

The first and second inputs of the excitation current regulator 5, as well as the non-inverting inputs proportional to the amplifier 27, are the reference inputs and receive signals from the setpoint 9 of the minimum excitation current and from the module 15 allocation module through the diodes 8 and 9, and the diodes serve to select the larger of these two signals. The third and sixth inputs of the regulator 5, as well as the inverting inputs of the amplifier .27, are corrective and they receive signals from the code (logical device 17 and through the nonlinearity block 14 from the output of the excitation winding temperature block 16. These signals reduce the reference value excitation current at exceeding the permissible value of the current core, for which the logic device 17 serves and when the permissible value of the winding temperature 3 excitations is exceeded, for which nonlinearity unit 14 and temperature detection unit 16 excitation winding. As a result, the proportional signal of the amplifier 28 appears at the output of the amplifier 28. This signal is compared at the input of the comparator 29 with feedback signals from the excitation current to the fourth and fifth inputs of the regulator 5 of the excitation current, as the inputs of the comparator 29.

The signal from the upstream sensor 11 of the excitation current is proportional to the actual value of the excitation current and forms a hard feedback. The output signal from the auxiliary excitation winding 18 is proportional to the derivative of the useful magnetic flux of the main poles and serves to dynamically stabilize the excitation control loop, forming a flexible feedback on the excitation current. Depending

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The ratio of the signal to the reference and the feedback signals at the output of the comparator 29 results in either a maximum positive or maximum negative signal. Thus, the controller 5 for the exciter on the basis of a magnetic silyel and power transistor switches actually implements a relay characteristic, which allows pulsing the output power transistor cascades with a small power loss. Capacitor 27 serves to limit the effect of interference.

In the controller 5 of the excitation current for the thyristor driver (Fig. 4) the proportional amplifier 32 and the capacitor 30 are identical with the amplifier 28 and the capacitor 27 (Fig. 3) and the same functions are performed. The difference between the two variants of the regulators lies in the fact that in the controller for the thyristor exciter, the reference signal and feedback signals are compared at the inverting input of the proportional amplifier 32. The signal at the output of the amplifier 33, as well as at the output of the controller 5, is determined the ratio of the signals at its inputs. This controller implements a proportional law, and a flexible feedback on the derivative of the magnetic flux provides dynamic stabilization of the excitation current control loop. Resistor 31 forms a deep negative feedback that serves to suppress the zero drift.

To determine the overheating of the excitation winding 3, the excitation winding temperature detection unit 16 (Fig. 5) serves. This block implements the dependency.

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excitation current value; excitation voltage value;

cold winding resistance; change in resistance of a winding under the influence of a heater.

To do this, the non proportional amplifier input 34, as well as the third input of the temperature detection unit 16, receives a signal from the excitation voltage sensor 3 proportional to Ug, and the inverting inputs, as well as the first and second inputs of the unit 16, arrive the signal from the excitation current sensor 11, proportional to i., and the signal from the output of the additional

winding 18, proportional to LT--.

As a result, the signal proportional to the overheating of the excitation winding 3 forms at the output of the proportional amplifier FOR, as well as at the output of block 16. The capacitor 35 serves to limit the influence of interference The signal from the output of block 16 of determining the temperature of the excitation winding arrives at the nonlinearity block 14 , having the characteristic of the dead zone type 5 which is shown in FIG. 7, When the temperature approaches an unacceptable level, a signal arrives at the input of the nonlinearity block 14, which is fed to the input of the regulator 5 excitation current and reduces the reference to the excitation current,

Thus, as a result of the application of the invention, the speed and reliability of the proposed electric drive is improved,

Claims (3)

Invention Formula 1, A DC motor containing a motor, the main winding of which is connected to an adjustable converter, and the excitation winding to the control driver, the control circuit of which is connected to the controller of the excitation current, the first and second inputs of which are connected excitation current and the first block of non-linearity type saturation through decoupling diodes, core current and excitation current sensors and voltage sensors on the core and voltage on the field winding, second block type nonlinearity deadband and vscheleni modulation unit, characterized in that, with a view to operating speed and povpieni five 0 five 0 five 0 five 0 five reliability, an excitation winding temperature detection unit and a mode detection unit are entered into it, and the electric motor is equipped with an additional excitation winding located at the main poles, the first, second and third inputs of the mode detection unit are connected respectively to the outputs of the current sensor of the voltage sensor bark and a module allocation unit connected by its output to the input of the first block of nonlinearity type saturation, and the output of the mode determination unit is connected to the third input of the current regulator The fourth and fifth inputs of which are connected respectively with the output of the excitation current sensor and the outputs of the additional excitation winding, which together with the output of the voltage sensor on the excitation winding are also connected to the inputs of the excitation winding temperature detection unit, the output of which through the second nonlinearity block of the zone type the insensitivity is connected to the sixth input of the excitation current regulator. 2. The electric drive according to claim 1, is about the fact that the mode detection unit contains a non-inverting proportional amplifier, two comparators, three diodes, a zener diode and a logic element EXCLUSIVE OR, while the cathode of the zener diode serves as the second input of the mode determination unit, the anodes the first and third diodes form its first and third inputs, and their cathodes are connected to the inputs of an EXCLUSIVE OR logic gate, the output of which is connected to the cathode of the third diode, is connected through the indicated diode to the limiting input of non-inverting a proportional amplifier, whose input is connected to the anode of the Zener diode, and the output is the output of the mode detection unit. 3. The electric drive according to claim 1, which is characterized by the fact that the excitation current controller contains a capacitor and connected in series with a proportional amplifier and comparator, the output of which is the output, and the inputs are the fifth and sixth inputs of the excitation current controller, the first and second non-inverting proportional amplifier inputs Omfs 1-g 2 f1 2S QfftfO and go iG .. From 18 ff.fn fi o fi J22 , “Pm Omt e / g Jl FIG. five r.5-f.8Ijtff t / g 7