SYSTEMS FOR AUTOMATIC CONTROL OF CRYSTAL GROWTH BY THE CHOCHRALSKI METHOD UNDER THE CONTROL OF A CONTINUOUS PID REGULATOR

The article describes systems for automatic control of crystal growth using the Czochralski method under the control of a continuous PID controller. A description is given of a series of computational experiments in the interactive software environment SimInTech, during which the accumulation of experimental data on crystal growth using the Czochralski method under the control of a continuous PID controller was carried out: the coefficients of the model of the control object were calculated and the coefficients of the PID controller were determined based on the constructed mathematical model and a given reference transient process . Conclusions are drawn about the operation of the systems: the controller gain plays a key role in this system, two other parameters play an auxiliary role to ensure the stability and quality of the transient process; the greater the gain of the regulator, the shorter the control time and the greater the damping coefficient of process oscillations with complex roots and the greater the damping effect; the control object was described by a first-order aperiodic link. A more accurate approximation will be obtained when described by an aperiodic or conservative second-order link. The article substantiates the thesis that an even more accurate description of the control object should take into account the slight delay of the signal on the transient response, using a pure delay link. It is also justified why it should be taken into account that as the crystal grows, the parameters of the controlled object change, in which case they resort to adaptive optimization of the control process by changing the parameters of the PID controller; it is also possible to use the optimizer built into the SimInmTech system. In the future, to create a regulatory process, it is currently possible to use regulators based on fuzzy principles.

Keywords:PID controller, automatic control systems, growing single crystals, Czochralski method, technologies for producing single crystals from a melt, automatic control systems