Design and implementation of the temperature control system for thermostat based on QCTS

Thermostat which is used in high accuracy temperature calibration requires stable,consistent temperature field.In order to satisfy the demand,the temperature control syaytem of the thermostat was designed and imp lemented by adopting quartz crystal temperature sensor(QCTS),microprocessor PIC16F876 and fuzzy PID control method.The circuit of QCTS temperature test and PWM output control were presented.The designing process of Fuzzy controller by using of Matlab Fuzzy control tool box were introduced.The results of simulations and experiments show that the temperature controlling system possessing fast response,high precision and robust over large temperature scope.The experimental result s indicate that and the temperature stability is better than ±0.05℃ per 15 minutes within the range from 0℃ to 100℃.