| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect overload on a motor by preventing a detection circuit for lock currents from causing detection error due to noises such as fluctuation of a power source, or to individual difference. <P>SOLUTION: The peak value of a motor current Ia is detected for each cycle of an AC power source, and the detected peak value is replaced with older ones, in order, and is stored in a memory means of a micro processor U2. An average value of the stored peak values is calculated, to calculate a reference value which has been added with a tolerable value. The reference value is compared with a current value which is detected by a detecting means, and if the current value exceeds the reference value, an overcurrent is judged to have flowed. An overload on a motor M1 is detected by avoiding detection error of the detection circuit of a lock current due to noises such as fluctuation of a power source or individual difference, by comparing the reference value that has absorbed noise and error with a detected current value. <P>COPYRIGHT: (C)2008,JPO&INPIT |
