Limit cycle autotuning method and heat/cool control apparatus

A limit cycle autotuning method of calculating a control parameter by alternately performing operation of outputting a predetermined heat-side manipulated variable set point to a heating actuator and operation of outputting a predetermined cool-side manipulated variable set point to a cooling actuator in a heat/cool control apparatus which performs temperature control by performing feedback control computation with respect to a deviation between a set point and a controlled variable on the basis of the control parameter, and properly switching a heat mode of outputting a manipulated variable to the heating actuator and a cool mode of outputting a manipulated variable to a cooling actuator, comprising:

• the first limit cycle generation step of generating a first limit cycle of alternately outputting the heat-side manipulated variable set point and the cool-side manipulated variable set point;
• the first control response detection step of detecting a first control response corresponding to the first limit cycle;
• the manipulated variable change ratio calculation step of determining, on the basis of the first control response, change instruction information for instructing which one of the heat-side manipulated variable set point and the cool-side manipulated variable set point is to be changed after the first limit cycle and a manipulated variable change ratio indicating a degree of the change;
• the second limit cycle generation step of generating a second limit cycle by changing one of the heat-side manipulated variable set point and the cool-side manipulated variable set point on the basis of the change instruction information and the manipulated variable change ratio;
• the second control response detection step of detecting a second control response corresponding to the second limit cycle;
• and
• the control parameter calculation step of calculating the control parameter for each of the heat mode and the cool mode on the basis of the detected first and second control responses.

A heat/cool control apparatus which has a limit cycle autotuning function of calculating a control parameter by alternately performing operation of outputting a predetermined heat-side manipulated variable set point to a heating actuator and operation of outputting a predetermined cool-side manipulated variable set point to a cooling actuator, and performs temperature control in normal operation by properly switching a heat mode of outputting a manipulated variable to the heating actuator and a cool mode of outputting a manipulated variable to the cooling actuator, comprising:

• control computation means for calculating a manipulated variable to the heating actuator or the cooling actuator by performing feedback control computation with respect to a deviation between a set point and a controlled variable on the basis of the control parameter in the normal operation;
• manipulated variable change ratio storage means for storing in advance change instruction information for instructing which one of the heat-side manipulated variable set point and the cool-side manipulated variable set point is to be changed during the autotuning, and a manipulated variable change ratio indicating a degree of the change;
• limit cycle generating means for generating a second limit cycle, during execution of the autotuning, by changing one of the heat-side manipulated variable set point and the cool-side manipulated variable set point on the basis of the change instruction information and the manipulated variable change ratio after generating a first limit cycle of alternately outputting the heat-side manipulated variable set point and the cool-side manipulated variable set point;
• control response detection means for detecting a first control response corresponding to the first limit cycle and a second control response corresponding to the second limit cycle;
• and
• control parameter calculation means for calculating the control parameter for each of the heat mode and the cool mode on the basis of the detected first and second control responses, and setting the calculated control parameters in said control computation means.