| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a detection circuit capable of accurately determining a state of a sensorless motor at the time of starting the motor. <P>SOLUTION: A plurality of comparators CMP<SB POS="POST">U</SB>-CMP<SB POS="POST">W</SB>are provided to a plurality of coils L<SB POS="POST">U</SB>-L<SB POS="POST">W</SB>respectively, compare counter electromotive forces V<SB POS="POST">U</SB>-V<SB POS="POST">W</SB>generated at one end of a corresponding coil with a midpoint voltage V<SB POS="POST">COM</SB>, and generate detection signals BEMF<SB POS="POST">U</SB>-BEMF<SB POS="POST">W</SB>representing the comparison result. Delay circuits 62<SB POS="POST">U</SB>-62<SB POS="POST">W</SB>delay the detection signals BEMF<SB POS="POST">U</SB>-BEMF<SB POS="POST">W</SB>outputted respectively from the plurality of comparators CMP<SB POS="POST">U</SB>-CMP<SB POS="POST">W</SB>by a predetermined time τ. A determination part 70 compares pre-delay detection signals BEMF<SB POS="POST">U-W</SB>and post-delay detection signals BEMFD<SB POS="POST">U-W</SB>with predetermined expected value patterns EXP1 and EXP2. <P>COPYRIGHT: (C)2012,JPO&INPIT |
