PROCESS AUTOMATION
Advanced Control Logics
TBB improved the control performances in controlling the diameter and pulling speed of silicon single crystal growers by using
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Enhanced control logics (feedback control, feedfoward control, iterative learning control, sequence control, etc.)
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Signal processing techniques (median-average filter, bumpless techniques, etc.)
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Resolution enhancers (PWM, dither, DSM, noise-suppressing parameter adjustment, etc.)
As a result, we overcomed the limitations of the previous control logics and achieved much better control performances:
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Variance in diameter reduced by 15%
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Average pulling speed increased by 20% (that leads to higher productivity)
Central Control and Monitoring System
TBB designed a central control/monitoring system for Si single crystal growers based on PROMONICON. This system can access 100+ growers to monitor and control the growing process. The topology of the central control/monitoring system for growers is presented as below:
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Each grower has its own PLC and local control/monitoring system.
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The local and central control/monitoring system are connected through PLC and TCP communication.
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The central control/monitoring system can manipulate multiple growers in a simultaneous manner by interfacing with PLCs through TCP communication.
The attributes of the central control/monitoring system include:
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Redundancy assured: a grower can be controlled by either its own local control/monitoring system or the central control/monitoring system. For examples, the local control/monitoring system will take over control automatically in a bumpless way if the central control/monitoring system is failed, vice versa.
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Automatic reporting: the central control/monitoring system collects process data of all the growers and processes them, followed by generating reports in an automatic way.
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Designing/applying recipes to multiple growers in an automatic way
Operator Training System
Operator Training System (OTS) is developed by using the simulation functions of PROMONICON. The OTS consists of a real-time virtual process, an operation/control system, and PLC.
The real-time virtual process is developed with the simulation module of PROMONICON. The virtual process is defined by transfer functions (i.e., differential equations) and algebraic equations, which emulates important dynamics in the single crystal growing process. The virtual process receives the manipulated variable signals (such as pulling speed, heater power, etc.) determined by the operation/control system through PLC, and sends the emulated measurements (process variables such as ingot diameter, melt temperature, etc.) to the operation/control system through PLC.
This system is useful to validate the operation/control logics and train the operators.
Image Processing
With the image processing module of PROMONICON, the following key variables (not measurable) to control and operate the silicon single crystal grower can be obtained.
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Good dip
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Crystal loss
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Diameter
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Melt gap
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Melt temperature
