Babenko Artyom Vladimirovich

Electrotechnical faculty

Speciality: Electromechanics systems of automation and electrical drive

Theme of master's work:

«Analysis and synthesis of the control systems by position electric drive»

Scientific adviser: doctor of engineering sciences, profesor Tolochko Ol'ga Ivanovna

Abstract

1. Purpose of work and actuality

2. Development of digital assign device, forming optimum diagrams of working off moving

3. Practical realization of researches

4. Conclusion

5. Literature

Purpose of work and actuality

    The primary purpose of this work is development of forming algorithm of control signals, for the direct current position electrical driving systems with independent and unregulated excitation. Development of algorithm is executed from a condition of maintenance of a minimum thermal losses in the motor armature at working off the assigned moving for the assigned time. The algorithm is developed taking into account restrictions on an armature current and speed at presence on the motor shaft a constant static reactive moment. Such problem is actual, for example, for drives of blooming rolling mills screw - down mechanism.
    In the majority of the works, devoted to the search of control optimum on thermal losses apply restriction not on the complete armature current, and on acceleration, proportional to a dynamic constituent of a current or a moment.

Development of digital assign device, forming optimum diagrams of working off moving

    For forming optimum diagrams it is enough to have only the coordinates of the graphs knots, however for the choice of the required diagram it is necessary to know expression for the calculation of the maximal value of speed without taking into account restriction on this coordinate.
Possible types of optimum diagrams for the set task in relative units are represented on the fig. 1:

Figure 1 - Optimum diagrams of working off the set moving on heating

    a, b, c - the area of motion with permanent speed is absent in a diagram ( high speed does not reach a level of restriction );
    d, e, f - in a diagram there is an area of work with the set high possible speed;
    a, d - the current does not reach a level of restriction;
    b, e - the current reaches a level of restriction only at acceleration;
    c, f - the current reaches a level of restriction both at acceleration and at braking.
    The algorithm of a choice the optimum diagram is represented on the fig. 2.

Figure 2 - Algorithm of choice optimum diagram

Practical realization of researches

    While carrying out the researches of the direct current position electrical drives we shall take advantage of experimental installation located in laboratory 8109. The power part of installation includes two motors of direct current of machine-tool series (PBST), two thyristor converters ET6. The tachogenerator, located on the same shaft with researched machine М1 is used as the speed transducer. Shaft of researched and loading machines are connected rigidly, without springs and backlashes. On the side of the loading machine M2 the opportunity of connection the thirteen width code transducer KD3, which can act as the speed and position sensor is provided.
    The IBM-PC compatible computer Pentium III (600 Mhz) acts as control ECM. Analog-digital transformation of feed-backs signals and digital-analog transformation of control influences is carried out by the 5710 Octagon Systems card. Thy entrance analog signals acting from the speed transducer and current transducers are galvanic untied by three modules 5B41 Analog Devices. For a galvanic isolation of output signals ( tasks on SIPC ) are used two modules7B22 same manufacturer Analog Devices.
    The control ECM works under the control of operational system real time QNX. It is favorably allocated with the most complete instrumental resource kit, to which the user has got used in DOS or UNIX, provides all inalienable making real-time systems: multitasking, traffic control of the programs centralized on the basis of priorities and rapid context switching. Firmware part of installation consists of one knot, which is the IBM PC compatible office computer ( on composition similar to the industrial controller ) with a necessary set of peripheral units working under the control of real time OS QNX 4.25.
    The period of discrete of digital control machine makes 0,5 milliseconds. Except for function of control on the system are assigned the functions of visualization with possibility of operative control of the system from the keyboard of computer. Registration of necessary signals ( both internal and external signals of system ) is carried out with frequency 2Khz. The opportunity of record of signals with set prehistory is sipulated. Tht amount of written down information is limited to the volume of the allocated memory from total amount of main memory for this task and makes 16MB.
    Development of the electrical drives control system was carried out with the help of package Simulink in MatLab environment. For communication of the control program with the electrical drive the driver of card of analog input - output 5710 Octagon systems is used.

Conclusion

    Now became possible, with the help of digital control systems, to realize algorithms of work of optimum diagrams. That allows to organize in the best way optimum on speed and losses a control system of electrical drives .

Literature

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