Model-based predictive control of thermal processing

A temperature control system for controlling a thermal process comprising:

• a controllable source of thermal energy which comprises multiple independently controllable thermal energy generators to heat an object;
• a plurality of temperature sensors, each of which measures a temperature related to an actual temperature of said object and which generates an output signal responsive to said temperature;
• and
• a model-based predictive temperature controller which receives said output signals and which controls said source of thermal energy in response to said output signals, said controller comprising:
• a nonlinear thermal process model which relates a process input thermal energy to a process output temperature;
• a prediction calculator which uses said nonlinear thermal process model to calculate a predicted nominal temperature output over a predetermined future time period;
• and
• a control calculator which uses said predicted nominal temperature output to calculate an optimum strategy by which to control said source of thermal energy to minimize spatial thermal gradients across said object, said controller generating output signals to said source of thermal energy in response to said optimum strategy, said control calculator configured to compare a predicted nominal temperature output to a desired future temperature output and use said comparison in an algorithm to compute said optimum strategy.

A method of controlling a thermal process comprising the steps of:

• measuring one or more process output temperatures;
• predicting a plurality of future process output temperatures by using a nonlinear thermal process model;
• using said one or more measured process output temperatures and said predicted future process temperatures to calculate an optimum process input control strategy by comparing one or more of said predicted future process output temperatures to a desired future temperature and using said comparison in an algorithm to compute said optimum process input control strategy;
• and
• controlling a process input thermal energy using the calculated optimum process input control strategy.

A temperature controlled thermal process reactor comprising:

• a reaction chamber enclosing an object to be headed;
• a plurality of sources of thermal energy which heat said object;
• a plurality of thermal sensors, each sensor configured to measure a sensor temperature, each sensor temperature related to an actual temperature of said object, where each thermal sensor provides an output signal representative of said sensor temperature, and wherein each of said sources of thermal energy affects each of said sensor temperatures;
• and
• a model-based predictive temperature controller which receive said output signals and which controls said sources of thermal energy in response to said output signals to produce a selected spatial and temporal distribution of heat energy to maintain a relatively uniform actual temperature on said object said model-based predictive temperature controller comprising a multivariable thermal process model that relates multivariable process input thermal energy to multivariable process output temperature, a prediction calculator that uses said thermal process model to calculate a predicted nominal temperature output over a predetermined future time period and a control calculator that uses said predicted nominal temperature output to calculate an optimum control strategy by which to control said sources of thermal energy said control calculator adapted to compare a predicted nominal temperature output to a desired future temperature output and use said comparison in a recursive algorithm to compute an optimum contort strategy.

A temperature control system for controlling a thermal process comprising:

• a controllable source of thermal energy which comprises multiple independently controllable thermal energy generators to heat an object;
• a plurality of temperature sensors, each of which measures a temperature related to an actual temperature of said object and which generates an output signal responsive to said temperature;
• and
• a model-based predictive controller which receives said output signals and which controls said source of thermal energy in response to said output signals, said controller comprising;
• a thermal process model that relates process input thermal energy to process output temperature;
• a prediction calculator that uses said thermal process model to calculate a predicted nominal temperature output over a predetermined future time period;
• and
• a control calculator that uses said predicted nominal temperature output to calculate an optimum strategy by which to control said source of thermal energy to minimize spatial thermal gradients across said object, said controller generating output signals to said source of thermal energy in response to said optimum strategy said control calculator configured to compare a predicted nominal temperature output to a desired future temperature output and use said comparison in an algorithm to compute said optimum strategy.

A method of controlling a thermal process comprising:

• measuring a plurality of process output temperatures;
• predicting a plurality of future process output temperatures;
• using said measured process output temperatures and said predicted future process temperatures to calculate an optimum process input control strategy by comparing one or more of said predicted future process output temperatures to a desired future temperature and using said comparison in an algorithm to compute said optimum process input control strategy;
• and
• controlling a plurality of process input thermal energy sources using the calculated optimum process input control strategy to reduce spatial thermal gradients.