| 摘要 |
PURPOSE:To obtain a brushless motor which does not need a position detector such as a Hall element by obtaining switching signals of respective phases based on detection signals indicating that the induced voltages of a plurality of phases become the prescribed relationship. CONSTITUTION:Assume that the output of a comparator 3U is H, a transistor TrQ is ON and a coil 1U is energized, TrQ2-Q5 and Q9 are OFF, while Tr Q6-Q8 are ON. Accordingly, the output of a comparator 3U is H, the outputs of a comparators 3v, 3w are L, and coils 1v, 1w are not energized. Since the voltage at the point (V) becomes VS at a time t2, the output of the comparator 3v changes from L to H, the TrQ2 becomes ON, and the coil 1v is energized. Since the output of the comparator 3U becomes L, the TrQ1 becomes OFF, thereby turning the TrQ9 ON and allowing Q6 to maintain OFF and the output of the comparator 3w holds L, the coil 1U is interrupted, and the energization of the coil 1w is inhibited. The circuit state of each phase is shifted to the phase at the adjacent phase at a time t3, and similar operation is performed. |
