RU43702U1 - MICROPROCESSOR CONTROLLED DC THYRISTOR ELECTRIC DRIVE - Google Patents

Abstract

The utility model relates to electrical engineering, in particular, to the areas of automated electric drive and converter technology. The device comprises an electric motor, respectively connected to an armature thyristor converter and a thyristor exciter, the power inputs of which are connected to the mains, and their control inputs are connected via pulse transformers to the outputs of the microprocessor control unit, the inputs of which are connected to the outputs of the sensors of controlled values of the electric drive, to an analog tachogenerator and to the control panel, an analog speed controller, the inputs of which are connected respectively to the tachogenerator and analog output control unit, and an output - to an analog input of the microprocessor control unit, wherein the digital input of the latter is connected to the digital output control unit. In the device, an analog speed controller can be programmed with control from the microprocessor control unit.

Description

The utility model relates to electrical engineering, in particular, to the areas of automated electric drive and converter technology.

Known electric drive with a microprocessor control system (MPSU) thyristor electric drive [1], containing a thyristor converter, MPSU, sensors of adjustable values (current, motor speed, etc.) and a control panel. MPSU implements a system of pulse-phase regulation of the control angle of the thyristor converter, current and speed controllers, devices for separate control of sets of thyristors of the converter and protection devices. An analog tachogenerator connected to the MPSU through an ADC is used as a speed sensor.

The disadvantage of this device is the limited range of regulation of the minimum engine speed, which takes place due to insufficient measurement accuracy using low-level ADC signals, for example, 1-10 mV.

The closest in technical essence to the claimed solution and taken as a prototype is a thyristor electric drive according to [2]. The functional diagram of this drive is given in [2] on page 174. Here, the reversible thyristor converter TP is connected to the network and

DC motor M through a current sensor DT. The microprocessor system provides control of the TP control angle, current i and motor speed n, as well as the choice of a working group of thyristors. The engine speed control is carried out from the remote control, the analog tachogenerator BR is used as a speed sensor, connected to the microprocessor via the PNK (or ADC) voltage-code conversion unit.

The disadvantage of the prototype lies in the limited range of regulation of the minimum speed due to the error of the PNK unit when measuring small signals, which affects the static characteristics of the electric drive. For example, for a standard tachogenerator of the TP-80 type, having an output voltage of 20 V at a speed of 1000 rpm and a PNA error of 10 mV, we tentatively have a minimum measured tachogenerator voltage with an error of 10%

This voltage in this example corresponds to the maximum minimum motor speed

Below n _{min, the} speed cannot be adjusted with the required accuracy. However, in wide-adjustable electric drive systems

lower speeds are required, for example, n _min ≅ 0.1 rpm. This is fundamentally impossible to obtain in this case.

The technical result of the proposed solution is the improvement of the static characteristics of the electric drive.

The technical result is achieved by the fact that in a thyristor DC drive with microprocessor control, containing an electric motor connected respectively to an anchor thyristor converter and a thyristor exciter, the power inputs of which are connected to the mains, and their control inputs are connected via pulse transformers to the outputs of the microprocessor control unit, the inputs of which are connected to the outputs of the sensors of the controlled parameters of the electric drive, to the analog tachogenerator and to the remote Control additionally introduced external analog speed regulator, the inputs of which are respectively connected to the tachogenerator and the analog output control unit, and an output - to an analog input of the microprocessor control unit, wherein the digital input of the latter is connected to the digital output control unit. In the device, an analog speed controller can be programmed with control from a microprocessor unit.

A distinctive feature of the utility model is that the improvement of the static characteristics of the electric drive is achieved by connecting to the microprocessor control unit and the control panel

analog speed controller, which provides high-quality speed control with a wide change in input signals up to 0.1 mV.

Figure 1 shows a diagram of the inventive device, where the following notation:

1 - electric motor;

2 - field winding of an electric motor;

3 - anchor thyristor converter;

4 - thyristor converter for powering the field winding of the electric motor (thyristor exciter);

5, 6 - pulse transformers;

7 - sensors of controlled parameters of the electric drive;

8, 9 - current sensors, respectively, of the armature converter and thyristor exciter;

10 - conductivity sensor of the thyristors of the converter 3 (only in reversible electric drives);

11, 13 - temperature sensors, respectively, of the thyristors of the converter 3 and the armature of the motor 1;

12 - voltage sensor;

14 - microprocessor control unit having control inputs input 1 "- for input of an analog signal and" Ex. input 2 "- for a digital signal;

15 - external analog speed controller, for example, proportional-integral type, which can be programmable;

16 - analog tachogenerator;

17 - control panel with outputs U _s and i _z.v ;

U _s - the reference voltage, the magnitude and sign of which determine the level of speed and the direction of rotation of the electric motor;

U _pc - analog signal from the output of an external speed controller 15;

i _z.v - the driving signal in digital form, which determines the excitation current of the electric motor.

Figure 2 shows one of the possible functional diagrams of the microprocessor control unit 14 in relation to a non-reversible electric drive, made at the software level, where:

18, 19 - a system of pulse-phase control, respectively, converters 3 and 4;

20, 21 - current regulators, respectively, the armature and field winding;

22-25 - analog-to-digital converters (ADC) of the output signals, respectively, of the speed controller 15 and the sensors of the controlled parameters of the electric drive 7;

26 - protection device, the input of which signals from the corresponding ADC.

For a reversible electric drive, the functional circuit of block 14 is supplemented by a separate control device for a reversible armature thyristor converter 3 and other auxiliary units.

In the proposed device, the armature of an electric motor 1 having an excitation winding 2 is connected to an anchor thyristor converter 3, and the excitation winding is connected to a thyristor exciter 4, thyristor converters 3, 4 are connected to the mains, the input circuits of the thyristors through the corresponding pulse transformers 5 and 6 are connected to the outputs of the microprocessor control unit 14, the inputs of which are connected to the outputs of the sensors of the controlled parameters of current 8, 9, conductivity of thyristors 10, temperature 11, 13 and voltage 12, which control the first input of the microprocessor control unit 14 is connected to the output of an external analog speed controller 15, the inputs of which are connected to the analog tachogenerator 16 and to the analog output of the control panel 17, the digital output of the panel 17 is connected to the digital input of the microprocessor control unit.

The device (figure 1, figure 2) works as follows.

The inputs of the analog speed controller 15 are fed signals from the control panel 17 and the analog tachogenerator 16. A voltage U _s is supplied from the control panel, specifying the magnitude of the engine speed and its direction of rotation. The voltage at the output of the tachogenerator U _BR corresponds to the true engine speed. Speed controller output voltage

where k is the transmission coefficient;

T is the integration constant, which is a signal for setting the motor current and is supplied to the control input 1 of the microprocessor control unit 14. The digital control input 2 of the microprocessor control unit is used to set the drive excitation current i _h from the output of the control panel. The output signal U _PC and the analog signals of the controlled parameters of the drive are converted into digital form using the appropriate ADC 22-25.

The microprocessor control unit at the software level performs the following operational control algorithms:

- according to the signals for setting the excitation current i _z.v and the current sensor 9 of the thyristor exciter 4, the algorithm performs the proportional-integral controller of the excitation current of the motor 21 and the pulse-phase control system 19. The output signals of the system 19 (control pulses) are supplied to the thyristor converter 4 via pulse transformers 6. As a result, the excitation current of the motor is set at a given i _z.v with a static error of zero;

- the signals from the output of the analog speed controller U _PC and the current sensor 8 of the thyristor converter 3 executes the algorithm of the proportional-integral current controller of the armature of the motor 20 and the pulse-phase control system 18. Output signals

systems 18 are fed to the anchor transducer 3 and a current is set in the armature winding at the level specified by U _PC with a zero static error.

In general, the analog speed controller and program current controller provide high quality static characteristics of the electric drive, both in the field of ultra-low and high speeds. This result is achieved due to the effective analog-digital control of the electric drive, in which the analog speed controller provides high accuracy of the error of the deviation in speed, and the software current controller ensures the high quality of the motor current regulation taking into account the specific properties of the thyristor converter: semi-controllability, non-linearity and discrete control.

The excitation current regulator ensures the constancy of the excitation current of the motor in a single-zone electric drive and changes the excitation current in a two-zone electric drive.

The protection software block 26 implements the protective shutdown algorithm of the drive in emergency situations, such as a short circuit, exceeding the maximum or specified rotation speed, overheating of the motor or converter, etc. In this case, the corresponding current, voltage, and temperature sensors and ADCs are used to convert analog signals to digital view.

It should be noted that in the absence of an analog speed controller and replacing it with an analog in a program form, the drive will

have a smaller range of speed control and worse static characteristics, as is the case in the prototype.

To provide the self-tuning function of the electric drive, the device can use an analog programmable speed controller with inputs for setting the gear ratio and constant integration with control from a microprocessor control unit.

Sources of fame:

[1] V.G. Feinstein, E.G. Feinstein. Microprocessor control systems for thyristor electric drives. M: Energoatomizdat, 1986, 240 pp.

[2] V. M. Perelmuter, V. A. Sidorenko. Control systems for thyristor electric drives of direct current. M: Energoatomizdat, 1988, 303 p.

Claims (2)

1. Thyristor DC drive with microprocessor control, containing an electric motor connected respectively to the armature converter and thyristor exciter, the power inputs of which are connected to the mains, and their control inputs through pulse transformers are connected to the outputs of the microprocessor control unit, the inputs of which are connected to the outputs of the sensors controlled values of the electric drive, to the analog tachogenerator and to the control panel, characterized in that it additionally includes An external analog speed controller was used, the inputs of which are connected respectively to the tachogenerator and the analog output of the control panel, and the output to the analog input of the microprocessor control unit, while the digital input of the latter is connected to the digital output of the control panel. 2. The device according to claim 1, characterized in that it uses an analog programmable speed controller with control from the microprocessor control unit.