| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problem wherein the temperature variations in a heat-generating resistor is large, when temperature is detected by interrupting PWM control and the PWM control is restarted with identical period, and thermal stress is large, in a thermal flow rate measuring device that controls the heat-generating resistor by the PWM control at a prescribed temperature. <P>SOLUTION: When the PWM control is interrupted to detect the temperature TH20 of the heat-generating resistor 20, and the PWM control is restarted, on the basis of the result obtained by performing PID operation by a deviation value of the temperature and Duty conversion, the PWM control is started by the Duty value, based on the PID operation result of the preceding period, before the PID operation result at the period is obtained. Thereafter, because the interruption time of the PWM control is shortened by switching to the PWM control by the Duty value of the PID operation result of the period, the amount of decrease TH20d of the heat generating resistor 20 is suppressed, the temperature pulsation of the heat generating resistor is suppressed; and the thermal stress is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
