| 摘要 |
<p>PURPOSE:To simple detect a stall state with sufficient accuracy, by detecting such a state that an electricmotor holds a state, wherein the speed result value V thereof is a definite value or less and the current result value I thereof is a definite value or more, for a definite time or more as the stall state. CONSTITUTION:A comparator 7 compares the speed detection signal V inputted from a rotational speed detector with a preset reference speed value V0 and a bit signal A of 1 is outputted at the time of V<=V0 and a bit signal A of 0 is outputted at the time of V>V0. A comparator 8 compares the current detection signal I inputted from a current detector with a reference current value I0 and a bit signal B of 1 is outputted at the time of I>=I0 and a bit signal B of 0 is outputted at the time of I>I0. An AND circuit outputs an AND signal X when both of the input signals A, B are 1. Next, an allowance time T for preventing erroneous judgement is set by a timer 10 to be given to a delay circuit 11 to delay the signal X of AND 1 by the time T through the circuit 11. After such a state that the signal X is 1 is continued for the time T, a stall state wherein overload is applied to an electricmotor is judged. As a result, 1 is outputted from the circuit 11 as a stall detection signal ST.</p> |
