Electric Blanket With Multi-temperature Control

Electric blanket also named electric mattress pad is a blanket with anintegrated electrical heating device usually placed above the top bed sheet.Itcan be used for warming bed clothes to provide customs with a comfortablesleep.Because of its simplicity,low power consumption,noiseless,relativelycheap,etc..,it's rather suitable for those family without central heating.Inrecent years,with the improvement of people's living standard and thedevelopment of technology,electric blanket tend to develop in the direction ofsafety,reliability,comfort and user-friendliness.Therefore,the electric blanketwith the function of multi-temperature zone control aroused more and moreattention because it can achieve the demand of individual temperaturedifferentiation.In this design,the negative feedback was used as the control strategy andthe hardware which based on MCS-51serials MCU was built.During theoperation process,the sinusoidal AC zero crossing signal was captured byzero-crossing detection module and then sync pulse was generated as thebenchmark for controlling the phase-shift voltage regulator,the outputvoltage of three heating devices were changed simultaneously.Theincremental PID algorithm was introduced into this negative feedback loopcontrol system.ADC sampling temperature value was used as the feedbackparameter,as long as the temperature changes,the power output also adjustedin order to keep it constancy on the set point.The non-preemptive kernel was introduced for improving operatingefficiency,and every subroutine was programmed in this regard.Theincremental PID algorithm subroutine was successfully applied in51MCU.Through parameters tuning,the desired goal was achieved.