关于温度控制系统的位置型PID控制算法，设定温度比当前温度低时，PWM的占空比100，全是高电平，停止加热；设定温度比当前温度高很多时，PWM的占空比100，全是低电平，全速加热。-Temperature control system on the location-based PID control algorithm, set the temperature lower than the current temperature, PWM duty cycle of 100, is high, and stop heating　temperature much higher than when the current temperature, PWM' s duty than 100, are all low-level, full-speed heating.